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WO2024258739A1 - Procédés et appareils pour configurer des paramètres pour une mobilité déclenchée par une couche inférieure à l'aide d'indicateurs de configuration de transmission - Google Patents

Procédés et appareils pour configurer des paramètres pour une mobilité déclenchée par une couche inférieure à l'aide d'indicateurs de configuration de transmission Download PDF

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Publication number
WO2024258739A1
WO2024258739A1 PCT/US2024/032991 US2024032991W WO2024258739A1 WO 2024258739 A1 WO2024258739 A1 WO 2024258739A1 US 2024032991 W US2024032991 W US 2024032991W WO 2024258739 A1 WO2024258739 A1 WO 2024258739A1
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Prior art keywords
configuration
ltm
cell
message
tci state
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English (en)
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Chih-Hsiang Wu
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Google LLC
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Google LLC
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • H04W36/085—Reselecting an access point involving beams of access points
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • H04W36/087—Reselecting an access point between radio units of access points
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices
    • H04W88/085—Access point devices with remote components

Definitions

  • This disclosure relates to wireless communications and. more particularly, to configuring parameters for lower-layer triggered cell changes between a user equipment (UE) and a radio access network (RAN) using transmission configuration indicators (TCIs).
  • UE user equipment
  • RAN radio access network
  • TCIs transmission configuration indicators
  • the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as transfer of user-plane data, ciphering, integrity protection, etc.
  • the PDCP layer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP technical specification (TS) 36.323) and New Radio (NR) (see 3GPP TS 38.323) provides sequencing of protocol data units (PDUs) in the uplink direction (from a user device, also know n as a UE, to a base station (BS)) as well as in the downlink direction (from the BS to the UE).
  • EUTRA Evolved Universal Terrestrial Radio Access
  • NR New Radio
  • the PDCP sublayer provides signaling radio bearers (SRBs) and data radio bearers (DRBs) to the Radio Resource Control (RRC) sublayer.
  • SRBs signaling radio bearers
  • DRBs data radio bearers
  • RRC Radio Resource Control
  • the UE and BS may use SRBs to exchange RRC messages as well as non-access stratum (NAS) messages, and may use DRBs to transport data on a user plane.
  • NAS non-access stratum
  • the UE may use several ty pes of SRBs and DRBs.
  • the cells associated with the BS operating as the master node (MN) define a master cell group (MCG), and the cells associated with the BS operating as the secondary node (SN) define the secondary cell group (SCG).
  • MCG master cell group
  • SCG secondary cell group
  • the so-called SRB1 resources carry RRC messages, which in some cases include NAS messages over the dedicated control channel (DCCH), and SRB2 resources support RRC messages that include logged measurement information or NAS messages, also over the DCCH but with lower priority than SRB1 resources.
  • SRB1 and SRB2 resources allow the UE and the MN to exchange RRC messages related to the MN and embed RRC messages related to the SN
  • SRB1 and SRB2 may be referred to as MCG SRBs
  • SRB3 resources allow the UE and the SN to exchange RRC messages related to the SN and SRB3 may be referred to as SCG SRBs.
  • DRBs using the lower-layer resources of only the MN may be referred to as MCG DRBs.
  • DRBs using the lower-layer resources of only the SN may be referred to as SCG DRBs.
  • DRBs using the lower-layer resources of both the MCG and the SCG may be referred to as split DRBs.
  • Split SRBs allow the UE to exchange RRC messages directly with the MN via lower layer resources of the MN and the SN.
  • the UE may concurrently utilize resources of multiple RAN nodes (e.g., BSs or components of a distributed BS), interconnected by a backhaul.
  • RAN nodes e.g., BSs or components of a distributed BS
  • RATs radio access technologies
  • this type of connectivity 7 is referred to as Multi-Radio Dual Connectivity 7 (MR-DC).
  • MN master node
  • SN secondary node
  • PSCell primary secondary cell
  • the UE communicates with the MN (via the PCell) and the SN (via the PSCell).
  • the UE utilizes resources of one BS at a time.
  • One BS and/or the UE determines that the UE should establish a radio connection with another BS. For example, one BS may determine to hand the UE over to the second BS and initiate a handover procedure.
  • a serving cell change is performed for the UE.
  • the RAN configures the UE to transmit Layer 3 (L3) measurement results.
  • L3 measurement results received from the UE, the RAN transmits an RRC reconfiguration message to the UE.
  • the RRC reconfiguration message triggers a Reconfiguration with Synchronization (e.g., the RRC reconfiguration message includes a ReconfigurationWithSync IE) for changing/switching the serving cell (e.g., PCell or PSCell).
  • the RAN releases the at least one SCell due to the change of the PCell or PSCell.
  • the serving cell change involves complete Layer 2 (L2) (and Layer 1 (LI)) resets, leading to long latency, large overhead, and a long interruption time.
  • L2 Layer 2
  • LI Layer 1
  • Recently developed lower-layer triggered mobility 7 (LTM) techniques do not use L3 reporting. These techniques reduce latency and overhead, thereby enabling faster serving cell switching. Configuring the LTM parameters for such a case remains an issue, which, if not solved efficiently, diminishes the LTM technique’ advantages.
  • TCI transmission configuration indicator
  • the LTM techniques reduce conventional cell switching latency and overhead because, for the LTM, the UE does not require explicit RRC signaling and lower layer resets.
  • the network may initiate an LTM cell change procedure based on an LI measurement report.
  • a BS which includes a centralized unit (CU) and a distributed unit (DU), transmits information related to lower-layer measurements and reporting (e.g., a reference signal configuration and/or an LI measurement report configuration), to the UE, together with an LTM DU configuration.
  • the BS may direct the UE to change a serving cell used for communication.
  • the LTM DU configuration and a TCI state configuration are exchanged between various entities (e.g., UEs, DUs, CUs, etc.) to configure parameters for the LTM cell switch and to enable seamless communications.
  • FIG. 1 A is a block diagram of an example system in which a RAN and a UE implement various techniques of this disclosure for transmitting LTM and TCI state configurations between an UE and a distributed BS.
  • FIG. IB is a block diagram of an example base station including a CU and a DU that can operate in the system of FIG. 1A.
  • FIG. 2A is a block diagram of an example protocol stack according to which the UE of FIG. 1A communicates with the BS.
  • FIG. 2B is a block diagram of an example protocol stack according to which the UE of FIG. 1 A communicates with a CU and a DU of the BS.
  • FIG. 2C is a block diagram illustrating structural elements of a network element and/or a BS configured to perform methods for managing LTM configurations and TCI state configurations according to an embodiment.
  • FIG. 3 illustrates a signaling diagram of a first scenario for a UE and an BS having a single DU operating according to an embodiment.
  • FIG. 4 illustrates a signaling diagram of a second scenario for a UE and an BS having plural DUs operating according to another embodiment.
  • FIGs. 5A and 5B illustrate signaling diagrams of a third scenario for a UE and plural BSs operating according to other embodiments.
  • FIGs. 6A and 6B illustrate signaling diagrams of a fourth scenario for a UE and plural BSs, at least one BS having plural DUs, operating according to yet other embodiments.
  • FIGs. 7A and 7B illustrate signaling diagrams of a fifth scenario for UE operating in dual connectivity with two DUs of an BS according to some embodiments.
  • FIGs. 8A and 8B illustrate signaling diagrams of a sixth scenario for UE operating in dual connectivity with two of plural DUs of an BS according to some other embodiments.
  • FIGs. 9 A and 9B are flowcharts of CU methods for generating and transmitting TCI state configurations for LTM according to various embodiments.
  • FIG. 10 is a flowchart of a CU method for transmitting a TCI state configuration for LTM according to an embodiment.
  • FIG. 11 is a flowchart of a DU method for transmitting a TCI state configuration for LTM according to an embodiment.
  • FIGs. 12A and 12B are flowcharts of DU methods for generating and transmitting TCI state configurations for LTM according to various embodiments.
  • FIGs. 13A and 13B are flowcharts of DU methods for generating a TCI state configuration based on a received TCI state configuration for LTM according to various embodiments.
  • FIGs. 14A and 14B are flowcharts of DU methods for generating a TCI state configuration based on a received TCI state configuration and generating an LTM DU configuration according to various embodiments.
  • FIG. 15 is a flowchart of a DU method for generating an additional serving DU configuration based on an LTM DU configuration and TCI state configuration according to an embodiment.
  • FIG. 16 is a flowchart of a DU method for generating an LTM DU configuration based on a received LTM DU configuration according to an embodiment.
  • FIG. 17 is a flowchart of a CU method for transmitting an LTM DU configuration based on reference signal resource configuration according to an embodiment.
  • FIG. 18 is a flowchart of a CU method for instructing a DU to generate an LTM DU configuration based on a sent LTM DU configuration according to an embodiment.
  • Methods and devices described in this section embody techniques for preparing a UE and/or a corresponding DU of a BS for LTM based cell change while using TCI state configuration.
  • an example wireless communication system 100 is introduced.
  • FIG. 1A depicts the wireless communication system 100 in which communication devices may implement the techniques discussed in this disclosure.
  • the wireless communication system 100 includes a UE 102, a first BS 104, a second BS 106, and a core network (CN) 110.
  • the UE 102 initially connects to the first BS 104.
  • the first BS 104 may perform an SN addition to configure the UE 102 to operate in dual connectivity (DC) with the first BS 104 and the second BS 106.
  • the BSs 104 and 106 operate as an MN and an SN, respectively, for the UE 102.
  • the first BS 104 may be implemented as a master eNB (MeNB) or a master gNB (MgNB), and the second BS 106 may be implemented as a secondary gNB (SgNB).
  • the UE 102 may communicate with the first BS 104 and the second BS 106 via the same RAT such as EUTRA or NR, or different RATs.
  • the UE 102 may be in EUTRA-NR DC (EN-DC) with the MeNB and the SgNB.
  • an MeNB or an SeNB is implemented as an ng-eNB rather than an eNB.
  • the BS 104 is a Master ng-eNB (Mng-eNB) and the BS 106 is a SgNB
  • the UE 102 may be in next generation (NG) EUTRA-NR DC (NGEN-DC) with the Mng-eNB and the SgNB.
  • NG next generation
  • NGEN-DC EUTRA-NR DC
  • the BS 104 is an MgNB and the BS 106 is an SgNB
  • the UE 102 may be in NR-NR DC (NR-DC) with the MgNB and the SgNB.
  • NR-DC NR-NR DC
  • the UE 102 may be in NR-EUTRA DC (NE-DC) with the MgNB and the Sng-eNB.
  • NE-DC NR-EUTRA DC
  • the BSs 104 and 106 operate as the source BS (S-BS) and a target BS (T-BS), respectively.
  • the UE 102 may operate in DC with the first BS 104 and an additional BS (not shown in FIG. 1 A), for example, prior to the handover.
  • the UE 102 may continue to operate in DC with the second BS 106 and the additional BS or operate in single connectivity (SC) with the second BS 106, after completing the handover.
  • SC single connectivity
  • the BSs 104 and 106 in this case operate as a source MN (S-MN) and a target [0034]
  • the CN 110 may be an evolved packet core (EPC) 1 11 or a fifth-generation core (5GC) 160, both of which are depicted in FIG. 1A.
  • the first BS 104 may be an eNB supporting an SI interface for communicating with the EPC 111, an ng-eNB supporting an NG interface for communicating with the 5GC 160. or a gNB that supports an NR radio interface as well as an NG interface for communicating with the 5GC 160.
  • the BSs 104 and 106 may support an X2 or Xn interface.
  • the EPC 111 may include a Serving Gateway (SGW) 112, a Mobility Management Entity (MME) 114, and a Packet Data Network Gateway (PGW) 116.
  • SGW Serving Gateway
  • MME Mobility Management Entity
  • PGW Packet Data Network Gateway
  • the SGW 112 is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc.
  • MME Mobility Management Entity
  • PGW Packet Data Network Gateway
  • the SGW 112 is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc.
  • the MME 114 is configured to manage authentication, registration, paging, and other related functions.
  • the PGW 116 provides connectivity from the UE to one or more external packet data networks, e.g., an Internet network and/or an Internet Protocol (IP) Multimedia Subsystem (IMS) network.
  • IP Internet Protocol
  • IMS Internet Multimedia Subsystem
  • the 5GC 160 includes a User Plane Function (UPF) 162 and an Access and Mobility Management (AMF) 164, and/or Session Management Function (SMF) 166.
  • the UPF 162 is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc.
  • the AMF 164 is configured to manage authentication, registration, paging, and other related functions,
  • the SMF 166 is configured to manage PDU sessions.
  • the first BS 104 supports cell 124 A (called serving cell in this disclosure), and the second BS 106 supports a cell 126.
  • the cells 124A and 126 may partially overlap, so that the UE 102 may communicate in DC with the first BS 104 and the second BS 106, where one of the BSs 104 and 106 is an MN and the other is an SN.
  • the first BS 104 may support additional cell(s) such as cells 124B and 124C
  • the second BS 106 may support additional cell(s) (not shown in FIG. 1A).
  • the cells 124A, 124B, and 124C may partially overlap, so that the UE 102 communicates with the first BS 104 using CA.
  • the first BS 104 may operate cells 124 A, 124B, and 124C via one or more transmit and receive points (TRPs). More particularly, when UE 102 is in DC with the first BS 104 and the second BS 106, one of the BSs 104 and 106 operates as an MeNB. an Mng-eNB, or an MgNB, and the other operates as an SgNB or an Sng-eNB.
  • TRPs transmit and receive points
  • the wireless communication network 100 may include any suitable number of BSs supporting NR cells and/or EUTRA cells. More particularly, the EPC 111 or the 5GC 160 may be connected to any suitable number of BSs supporting NR cells and/or EUTRA cells.
  • EPC EPC, 5GC
  • RAT types 5GNR and EUTRA
  • the techniques of this disclosure also may apply to other suitable radio access and/or core network technologies such as sixth generation (6G) radio access and/or 6G core network or 5G NR-6G DC.
  • the first BS 104 is equipped with processing hardware 130 that may include one or more general-purpose processors (e.g.. CPUs) and a non-transitory computer-readable memory storing instructions that the one or more general- purpose processors execute. Additionally, or alternatively, the processing hardware 130 may include special-purpose processing units.
  • the processing hardware 130 may include a PHY controller 132 configured to transmit data and control signal on phy sical downlink (DL) channels and DL reference signals with one or more user devices (e.g., UE 102) via one or more cells (e.g., cell(s) 124A, 124B, and/or 124C) and/or one or more TRPs.
  • DL phy sical downlink
  • UE 102 e.g., UE 102
  • cells e.g., cell(s) 124A, 124B, and/or 124C
  • the PHY controller 132 is also configured to receive data and control signal on physical uplink (UL) channels and/or UL reference signals with the one or more user devices via one or more cells (e.g., cell(s) 124A, 124B, and/or 124C) and/or one or more TRPs.
  • the processing hardware 130 may include a MAC controller 134 configured to perform MAC functions with one or more user devices.
  • the MAC functions include a random access (RA) procedure, managing UL timing advance for the one or more user devices, and/or communicating UL/DL MAC PDUs with the one or more user devices.
  • the processing hardware 130 may further include an RRC controller 136 configured to implement procedures and messaging at the RRC sublayer of the protocol communication stack.
  • the RRC controller 136 may be configured to support RRC messaging associated with handover procedures, and/or to support the necessary operations when the first BS 104 operates as an MN relative to an SN or as an SN relative to an MN.
  • the second BS 106 may include processing hardware 140 that is similar to processing hardware 130.
  • components 142, 144, and 146 may be similar to the components 132, 134, and 136, respectively.
  • the UE 102 is equipped with processing hardware 150 that may include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general- purpose processors, and/or special -purpose processing units.
  • the PHY controller 152 is also configured to receive data and control signal on physical DL channels and/or DL reference signals with the first BS 104 or second BS 106 via one or more cells (e.g., the cell(s) 124A, 124B, 124C and/or 126) and/or one or more TRPs.
  • the PHY controller 152 is also configured to transmit data and control signal on physical UL channels and/or UL reference signals with the first BS 104 or second BS 106 via one or more cells (e.g., cell(s) 124 A, 124B, 124C, and/or 126) and/or one or more TRPs.
  • the processing hardware 150 in an example embodiment includes a MAC controller 154 configured to perform MAC functions with first BS 104 or second BS 106.
  • the MAC functions include a random access procedure, managing UL timing advance for the one or more user devices, and communicating UL/DL MAC PDUs with the first BS 104 or second BS 106.
  • the processing hardware 150 may further include an RRC controller 156 to implement procedures and messaging at the RRC sublayer of the protocol communication stack.
  • the UE 102 in DC may use a radio bearer (e g., a DRB or an SRB) that at different times terminates at MN 104 or the SN 106.
  • the UE 102 may apply one or more security keys when communicating on the radio bearer, in the UL (from the UE 102 to a BS) and/or DL (from a BS to the UE 102) direction.
  • FIG. IB depicts an example of a distributed configuration of a BS 170 (can be either the first BS 104, or the second BS 106, or both, or another BS).
  • the BS 170 in this embodiment may include a centralized unit (CU) 172 and one or more distributed units (DUs) 174.
  • the CU 172 is equipped with processing hardware that may include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units.
  • the CU 172 is equipped with processing hardware 130.
  • the CU 172 is equipped with processing hardware 140.
  • the processing hardware 140 in an embodiment includes an SN RRC controller 142 configured to manage or control one or more RRC configurations and/or RRC procedures when the second BS 106 operates as an SN.
  • the DU 174 is also equipped with processing hardware that may include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general -purpose processors, and/or special-purpose processing units.
  • the processing hardware includes a MAC controller configured to manage or control one or more MAC operations or procedures (e.g., a random access procedure) and a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures when the second BS 106 operates as an MN or an SN.
  • RLC radio link control
  • the process hardware may further include a physical layer controller configured to manage or control one or more physical layer operations or procedures.
  • FIG. 2A illustrates, in a simplified manner, an example protocol stack 200 which the UE 102 may use to communicate with an eNB/ng-eNB 201 A or a gNB/en-gNB 201B (e.g., one or more of the BSs 104, 106).
  • a physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA MAC sublayer 204A, which in turn provides logical channels to the EUTRA RLC sublayer 206A.
  • the EUTRA RLC sublayer 206A in turn provides RLC channels to an EUTRA PDCP sublayer 208 and, in some cases, to an NR PDCP sublayer 210.
  • the NR PHY 202B provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B.
  • the NR RLC sublayer 206B in turn provides data transfer services to the NR PDCP sublayer 210.
  • the NR PDCP sublayer 210 in turn may provide data transfer sen-ices to Service Data Adaptation Protocol (SDAP) 212 or a radio resource control (RRC) sublayer (not shown in FIG. 2A).
  • SDAP Service Data Adaptation Protocol
  • RRC radio resource control
  • the UE 102 in some embodiments, supports both the EUTRA and the NR stack as shown in FIG. 2 A, to support handover between EUTRA and NR BSs and/or to support DC over EUTRA and NR interfaces. Further, as illustrated in FIG. 2A, UE 102 may support layering of NR PDCP 210 over EUTRA RLC 206 A, and SDAP sublayer 212 over the NR PDCP sublayer 210.
  • the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 receive packets (e.g., from an IP layer, layered directly or indirectly over the PDCP layer 208 or 210) that may be referred to as service data units (SDUs). and output packets (e.g., to the RLC layer 206A or 206B) that may be referred to as protocol data units (PDUs). Except where the difference between SDUs and PDUs is relevant, this disclosure, for simplicity, refers to both SDUs and PDUs as “packets.”
  • SDUs service data units
  • PDUs protocol data units
  • the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide SRBs or RRC sublayer (not shown in FIG. 2A) to exchange RRC messages or NAS messages, for example.
  • the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide DRBs to support data exchange.
  • Data exchanged on the NR PDCP sublayer 210 may be SDAP PDUs, IP packets, or Ethernet packets.
  • FIG. 2B illustrates, in a simplified manner, an example protocol stack 250, which the UE 102 may use to communicate with a DU (e.g., DU 174) and a CU (e.g., CU 172).
  • the radio protocol stack 200 is functionally split as shown by the radio protocol stack 250 in FIG. 2B.
  • the CU at any of the BSs 104 or 106 may hold all the control and upper layer functionalities (e g., RRC 214, SDAP 212, and NR PDCP 210), while the lower layer operations (e.g., NR RLC 206B, NR MAC 204B, and NR PHY 202B) are delegated to the DU.
  • NR PDCP 210 provides SRBs to RRC 214
  • NR PDCP 210 provides DRBs to SDAP 212 and SRBs to RRC 214.
  • the term network entity is introduced in this disclosure to be one of the first BS 104, second BS 106 in FIG. 1A, the BS 170 in FIG. IB. the BSs 201A. 201B in FIG. 2A, or the units 174 or 172 in FIG. 2B).
  • the NE communicates wirelessly with UE 102.
  • NE may be a BS, more generally, the term “network entity” stands for a wireless device with a well-defined network functionality (e.g., BS’s functionality is connecting UEs to the core network including managing communications to and from the UEs).
  • NE and UE 102 may include additional functions and interfaces omitted from the figures in the interest of brevity.
  • the NE 170 which is schematically illustrated in FIG. 2C. may provide the functionality of an gNB (i.e., a 5G or 6G BS).
  • NE functionality may be distributed across multiple entities (e.g., CU, DU, and a radio unit, RU).
  • NE includes antennas, a Radio Frequency (RF) front end and a transceiver 282 for communicating with UE 102 and other UEs and NEs.
  • NE’s antennas and RF front end may be tuned to one or more frequency bands (e.g., subcarriers), for example as defined by 3GPP LTE, 5G NR, and 6G communication standards and implemented by transceiver.
  • RF Radio Frequency
  • NE 170 further includes processor(s) 283 and computer-readable storage media (CRM) 284.
  • Processor(s) 283 may include single or multiple-core processors, and CRM includes any suitable memory/storage except propagating signals.
  • memory /storage may include random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), and/or flash memory.
  • CRM 284 stores device data, which includes network scheduling data, radio resource management data, applications, and/or an operating system, which are executable by processor(s) to enable wireless communication with UE 102 as well as with other NEs and UEs.
  • CRM 284 also stores an LI measurement configuration and LTM control-related executable instructions.
  • NE also includes inter-BS interface and core-network interface.
  • Inter- BS interface may be a standardized interface, such as an Xn and/or X2 interface, for exchanging user-plane and control-plane data with another NE (e g., in case of a handover).
  • Core-network interface enables NE’s user-plane data and control-plane information exchange with core network functions and/or entities.
  • the NE’s and the UE’s LI measurement and LTM execution may be implemented not only as software but also as hardware logic and/or circuitry'.
  • event 316 is similar to event 416 of FIGs. 4A and 4B, event 516 of FIG. 5 A, event 517 of FIG. 5B, event 616 of FIG. 6A, event 617 of FIG. 6B, event 716 of FIG. 7A, and event 717 of FIG.
  • the first BS 104 includes a CU 172 and a DU 174, and the DU 174 operates the cell 124A (i.e., the serving cell).
  • UE 102 initially communicates 302 with the DU 174 on the serving cell 124A using a serving DU configuration and communicates with the CU 172 via the DU 174, e.g., using a serving CU configuration.
  • DU 174 is a serving DU that communicates with the UE 102.
  • the UE 102 communicates in CA with the DU 174 on the cell 124A and other cell(s) (e.g., cell 124D not shown in FIG.
  • the DU 174 operates the other cell(s).
  • the UE 102 communicates with the DU 174 only on cell 124A.
  • the UE 102 communicates with the DU 174 on the cell 124A and/or other cell(s) via one or multiple TRPs.
  • cell 124A may be a PCell.
  • the other cell(s) include SCell(s) and/or additional cell(s) associated with the PCell or a SCell.
  • the cell 124 A may be a SCell, and one of the other cell(s) is a PCell. In such cases, the rest? includes SCell(s) and/or additional cell(s) associated with the PCell or a SCell.
  • the first BS 104 may be the DU 174, the CU 172. or the DU 174 and CU 172.
  • the UE 102 may transmit UL PDUs and/or UL control signals to the first BS 104 on the cell 124A and/or other cell(s) via one or multiple TRPs.
  • the UE 102 communicates UL PDUs and/or DL PDUs with the first BS 104 via radio bearers which may include SRBs and/or DRB(s).
  • the first BS 104 may configure the radio bearers to the UE 102.
  • UL control signals include UL control information, channel state information, hybrid automatic repeat request (HARQ) acknowledgements (ACKs), HARQ negative ACKs, scheduling request(s) and/or sounding reference signal(s).
  • HARQ hybrid automatic repeat request
  • ACKs hybrid automatic repeat request acknowledgements
  • HARQ negative ACKs scheduling request(s) and/or sounding reference signal(s).
  • the UE 102 may receive DL PDUs and/or DL control signals from the first BS 104 on the cell 124A and/or other cell(s) via one or multiple TRPs.
  • the DL control signals include downlink control information (DCIs) and reference signals (e.g.. synchronization signal block, channel state information reference signal(s) (CSI-RS(s)), and/or tracking reference signal(s)).
  • the first BS 104 may transmit the DCIs on physical downlink control channel(s) (PDCCH(s)) monitored by the UE 102, on the cell 124A and/or other cell(s) via one or multiple TRPs.
  • PDCCH(s) physical downlink control channel(s)
  • the serving DU configuration includes physical layer configuration parameters, MAC configuration parameters, and/or RLC configuration parameters.
  • the DU 174 may transmit these configuration parameters to the CU 172.
  • the CU 172 generates one or more messages (e.g., RRC reconfiguration message(s)) including the configuration parameters and transmits one or more messages to the UE 102 via the DU 174.
  • the DU 174 transmits the configuration parameters to the UE 102 directly.
  • the serving DU configuration is CellGroupConflg IE defined in 3GPP TS 38.331.
  • the serving DU configuration includes configuration parameters in the CellGroupConflg IE.
  • the serving CU configuration includes PDCP configuration parameters, measurement configuration parameters, and/or radio bearer configuration parameters.
  • the serving CU configuration includes aMeasConfig IE and/or a RadioBearerConfig IE defined in 3GPP TS 38.331 or includes configuration parameters in the MeasConfig IE and/ or RadioBearerConfig IE.
  • the serving DU configuration includes a CSI-MeasConfig IE or configuration parameters for channel state information (CS1) measurement and reporting.
  • the serving CU configuration includes a CSI-MeasConfig IE or configuration parameters for CSI measurement and reporting.
  • UE 102 receives the serving CU configuration or the configuration parameters in the serving CU configuration from the CU 172 via the DU 174. In other embodiments, the UE 102 receives a portion of the serving CU configuration and/or a portion of the serving DU configuration from a BS other than the first BS 104 and the remaining portion of these configuration parameters from the first BS 104.
  • the UE 102 may transmit 304 at least one measurement report to the DU 174.
  • the at least one measurement report includes Layer 1 (LI) measurement report(s) and/or Layer 3 (L3) measurement report(s) for at least one serving cell of the UE 102 and/or at least one non-serving cell.
  • the DU 174 transmits 306 a DU-to-CU message including the L3 measurement report to the CU 172.
  • the DU-to-CU message(s) of the event 306 is/are Fl application protocol (F1AP) message(s) (e.g., UL RRC Message Transfer message(s)).
  • F1AP Fl application protocol
  • the DU 174 does not transmit or refrains from transmitting the LI measurement report(s) to the CU 172.
  • the at least one serving cell includes the cell 124A and/or other cell(s), and the at least one non-serving cell includes the cell 124B and/or cell 124C.
  • the serving DU configuration or the serving CU configuration includes at least one measurement configuration.
  • the UE 102 receives one or more RRC messages (e.g., RRCReconflguration message(s)) including the at least one measurement configuration from the CU 172 via the DU 174 in the event 302.
  • the UE 102 performs measurements and transmits 304 the at least one measurement report to the DU 174.
  • the at least one measurement configuration includes L3 measurement configuration(s) (e.g., MeasConfig IE(s)) and/or LI measurement configuration(s).
  • the LI measurement configuration(s) e.g., CSI-MeasConfig IE(s)
  • the LI measurement resource configuration(s) may configure reference signal(s) and/or resources of the reference signal(s) for the UE 102 to measure and obtain LI measurement results.
  • the reference signal(s) includes CSI-RS(s) and/or SSB(s).
  • the LI measurement resource configuration(s) is/are CSI- ResourceConfig IE(s).
  • the LI measurement reporting configuration(s) configures way(s) the UE 102 uses to transmit LI measurement results/reports.
  • the LI measurement report configuration(s) is/are CSI-ReportConfig IE(s).
  • UE 102 transmits the L3 measurement report(s) to the CU 172 via the DU 174 in accordance with the L3 measurement configuration(s).
  • UE 102 transmits the LI measurement report(s) to the DU 174 in accordance with the LI measurement configuration(s) or LI measurement reporting configuration(s). Tn one embodiment, the DU 174 does not transmit the LI measurement report(s) to the CU 172.
  • the LI measurement configuration(s) are new RRC IE(s) for a lower layer triggered mobility (LTM).
  • the LI measurement resource configuration(s) are new RRC IE(s) defined in 3GPP TS 38.331 for the LTM.
  • the LI measurement reporting configuration(s) are new RRC lE(s) defined in 3GPP TS 38.3 1 for the LTM.
  • each of the LI measurement reporting configuration(s) may include a trigger event configuration configuring a trigger event to trigger the UE 102 to transmit an LI measurement report. If UE 102 detects the trigger event, the UE 102 transmits an LI measurement report to the DU 174.
  • each of the LI measurement report(s) may include at least one LI measurement result.
  • the at least LI measurement result includes at least one LI -reference signal received power (Ll-RSRP) value and/or at least one LI- Signal to Interference Noise Ratio (Ll-SINR) value.
  • Ll-RSRP LI -reference signal received power
  • Ll-SINR LI- Signal to Interference Noise Ratio
  • each of the LI measurement report(s) is part of channel state information (CSI) (i.e., a CSI component) or CSI.
  • CSI channel state information
  • the UE 102 may include other CSI component(s) in (each of) the PUCCH transmission(s) and/or PUSCH transmission(s) described above.
  • the other CSI component(s) include such as a channel quality indicator (CQI), a Precoding Matrix Indicator (PMI), a CSI-RS Resource Indicator (CRI), a Sy nchronization Signal (SS)/ Physical Broadcast Channel (PBCH) Resource Block Indicator (SSBRI), a Layer Indicator (LI), and/or a Rank Indicator (RI).
  • CQI channel quality indicator
  • PMI Precoding Matrix Indicator
  • CRI CSI-RS Resource Indicator
  • SS Sy nchronization Signal
  • PBCH Physical Broadcast Channel
  • SSBRI Resource Block Indicator
  • LI Layer Indicator
  • RI Rank Indicator
  • UE 102 does not transmit the LI measurement report(s) as an RRC message(s) to the DU 174.
  • each of the L3 measurement report(s) may include at least one L3 measurement result.
  • the at least one L3 measurement result includes at least one RSRP (value) and/or at least one SINR (value).
  • the UE 102 transmits each of the L3 measurement report(s) on a PUSCH to the CU 172 via the DU 174.
  • each of the L3 measurement report(s) may be an RRC message (e.g., MeasurementReport message).
  • the UE 102 transmits 304 a MAC control element (CE) including the measurement report to the DU 174.
  • a MAC control element CE
  • the UE 102 generates one or more MAC PDUs, each including one or more of the MAC CE(s) to the DU 174 in the event 304.
  • the UE 102 performs measurements on one or more reference signals in accordance with the at least one measurement configuration.
  • the one or more reference signals may include one or more Synchronization Signal (SS)/ Physical Broadcast Channel (PBCH) Resource Blocks (SSBs), and/or one or more CSI-RSs.
  • SS Synchronization Signal
  • PBCH Physical Broadcast Channel
  • SSBs Resource Blocks
  • CSI-RSs CSI-RSs.
  • UE 102 generates the at least one LI measurement result and/or at least one L3 measurement result from the measurements.
  • the DU 174 transmits the one or more reference signals on the cell 124A and other cell(s) (e.g., the cell 124B, the cell 124C and/or cell(s) not shown in FIG. 1A).
  • the first BS 104 determines to prepare a first cell (e.g., the cell 124B), other than the serving cell, for LTM UE 102 switch.
  • a first cell e.g., the cell 124B
  • the term “prepare a cell’' is used in this disclosure to mean prepare a DU associated with the first cell, or prepare a CU associated with the first cell, or prepare the CU and DU associated with the first cell.
  • the first BS 104 determines to prepare the first cell for the UE 102 because the at least one measurement report indicates that the first cell could be used by the first BS 104 to communicate with the UE 102. In some embodiments, the first BS 104 determines to prepare the first cell for the UE 102 because the at least one measurement report indicates that the first cell qualifies to be a candidate cell that could be used for communication with the UE 102.
  • the CU 172 determines to prepare the first cell for the UE 102 switch.
  • the DU 174 determines to prepare the first cell for the UE 102 switch.
  • the first BS 104 determines to prepare the first cell for the UE 102 regardless of whether a measure report is received from the UE 102 or not.
  • the CU 172 transmits 308 a first CU-to-DU message to the DU 174 to prepare the first cell for the UE 102.
  • the CU 172 includes a cell identity (ID) of the first cell in the first CU-to-DU message to request the DU 174 to prepare the first cell for LTM for the UE 102.
  • the CU 172 includes a reference LTM DU configuration in the first CU-to-DU message.
  • the cell ID is cell global identity (CGI).
  • CGI cell global identity
  • the cell ID is a portion of the CGI.
  • the cell ID is a physical cell ID (PCI).
  • the DU 174 In response to the first CU-to-DU message, the DU 174 generates a first LTM DU configuration (referred to in this disclosure as LTM DU configuration 1) for the UE 102, which configures the first cell for LTM.
  • the DU 174 transmits 310 a first DU-to-CU message including the LTM DU configuration 1 to the CU 172 in response to the first CU-to- DU message.
  • the DU 174 may include the cell ID 1 together with the LTM DU configuration 1 in an IE of the first DU-to-CU message to indicate that the LTM DU configuration 1 is associated with the first cell (i.e., the cell ID 1).
  • the DU 174 determines to prepare the first cell, the DU 174 initiates transmission of the first DU-to- CU message to the CU 172 instead of in response to a CU-to-DU message received from the CU 172. In other words, either the DU 174 independently generates the LTM DU configuration 1 or the CU 172 instructs the DU 174 to generate the LTM DU configuration 1.
  • the DU 174 includes, in the first DU-to-CU message, the cell ID of the first cell associated with the LTM DU configuration 1 to indicate that the LTM DU configuration 1 is configured for or associated with the first cell.
  • the CU 172 identifies that the LTM DU configuration 1 is configured for or associated with the first cell.
  • the CU 172 may include additional cell ID(s) (e.g., cell ID(s) 2, . .. , N) in the first CU-to-DU message to prepare additional cell(s) (e.g., cell(s) 2, . ..
  • the DU 174 includes additional LTM DU configuration(s) (e.g., LTM DU configuration(s) 2. .... N). each configuring a particular cell of the additional cell(s), as described below.
  • the DU 174 includes, in the first DU-to-CU message, the additional cell ID(s) respectively associated with the additional LTM DU configuration(s) to indicate which LTM DU configuration is associated to which cell (ID).
  • the cell(s) 1 and/or 2, . . . , N are candidate cell(s).
  • the CU 172 does not include a (reference) LTM DU configuration in the first CU-to-DU message.
  • the DU 174 generates a reference LTM DU configuration, generates the LTM DU configuration(s) 1 and/or 2, . . . , N (i.e., nonreference LTM DU configuration(s)) based on the reference LTM DU configuration, and includes the reference LTM DU configuration in the first DU-to-CU message.
  • the CU 172 includes a reference LTM DU configuration in the first CU-to-DU message. In such cases, the DU 174 generates the LTM DU configuration(s) 1, and/or 2, ...
  • the CU 172 includes a reference LTM DU configuration (e.g., a first reference LTM DU configuration) in the first CU-to-DU message.
  • the DU 174 generates a reference LTM DU configuration (e.g., a second reference LTM DU configuration) replacing the first reference LTM DU configuration, generates the LTM DU configuration(s) 1 and/or 2, .. . , N based on the second reference LTM DU configuration, and includes the second reference LTM DU configuration in the first DU-to-CU message.
  • the reference LTM DU configuration includes physical layer configuration parameters, MAC configuration parameters, and/or RLC configuration parameters.
  • the reference LTM DU configuration is CellGroupConflg IE defined in 3GPP TS 38.331 .
  • the reference LTM DU configuration includes configuration parameters in the CellGroupConfig IE.
  • the reference LTM DU configuration includes a CSI-MeasConfig IE or configuration parameters for CSI measurement and/or reporting.
  • the reference LTM DU configuration is different from the serving DU configuration. In some embodiments, a portion of the reference LTM DU configuration is the same as a portion of the serving DU configuration and the rest of the reference LTM DU configuration is different from the rest of the serving DU configuration. In other embodiments, the reference LTM DU configuration is the same as the serving DU configuration.
  • the CU 172 After receiving the first DU-to-CU message, the CU 172 generates a RRC reconfiguration message (e.g., an RRCReconflguration message) including the LTM DU configuration 1 and transmits 316 a second CU-to-DU message including the RRC reconfiguration message to the DU 174.
  • the CU 172 includes the reference LTM DU configuration in the RRC reconfiguration message sent in step 316. In other embodiments, the CU 172 does not include a/the reference LTM DU configuration in the RRC reconfiguration message 316.
  • the CU 172 transmits the reference LTM DU configuration to the UE 102 during event 302, the CU 172 does not include the reference LTM DU configuration in the RRC reconfiguration message 316. In other embodiments, if the CU 172 receives the reference LTM DU configuration from the DU 174, the CU 172 includes the LTM DU configuration in the RRC reconfiguration message 316. Otherwrse, if the CU 172 does not receive a reference LTM DU configuration from the DU 174, the CU 172 does not include the reference LTM DU configuration in the RRC reconfiguration message 316.
  • the CU 172 includes the LTM DU configuration 1 and/or the LTM CU configuration 1 in a first container (e.g., a field/IE) and includes the first container (e.g., LTM configuration (e.g., LTM-Config IE)) in the RRC reconfiguration message of the events 316 and 318.
  • the CU 172 generates the first container.
  • the first container is to indicate the UE 102 not to immediately apply the LTM DU configuration 1 and/or the LTM CU configuration 1.
  • the UE 102 receives an RRC reconfiguration message (e.g., the RRC reconfiguration message of the event 318) including a configuration (e.g...
  • the first container includes a first addition or modification list (e.g., Itm-ConfigToAddModList field. LTM-ConfigToAddModList IE, Itm-CandidateConflgToAddModList field, or LTM- CandidateConflgToAddModList IE).
  • the CU 172 includes the LTM DU configuration 1 and/or the LTM CU configuration 1 in a first element (referred to herein after as element 1) of the first addition or modification list.
  • element 1 may be an addition or modification IE (Itm-ConflgToAddMod field, LTM-ConflgToAddMod IE, Itm- CandidateConflg oAddMod field, or LlM-CandidateConflglbAddMod IE).
  • the UE 102 may store the first addition or modification list, e.g., as a variable in its RAM.
  • the DU 174 generates the first container and includes the first container in the first DU-to-CU message.
  • the DU 174 generates element 1 and includes element 1 in the first DU-to-CU message.
  • the CU 172 includes an LTM CU configuration 1 in the RRC reconfiguration message 316, the first container or the element 1, where the LTM CU configuration 1 is associated with the LTM DU configuration 1.
  • the CU 172 may include the LTM CU configuration 1 and the LTM DU configuration in element 1.
  • the CU 172 includes LTM CU configuration(s) 2, ... , N in the RRC reconfiguration message 316 or the second container, where the LTM CU configuration(s) 2, . . . , N associated with the LTM DU configuration(s) 2, ... , N, respectively.
  • the LTM CU configuration(s) 2 ...
  • the CU 172 may include the LTM CU configuration(s) 2, . .. , N and the LTM DU configuration(s) in the element(s) 2, .. . , N, respectively.
  • the CU 172 includes, in the element(s) 2, ... , N, the LTM CU configuration(s) 2, . .. , N associated with the LTM DU configuration(s) 2, . . . , N, respectively.
  • the CU 172 does not include, in the RRC reconfiguration message 316, LTM CU configuration(s) for some or all of the LTM DU configuration 1 and/or LTM DU configuration(s) 2, . .. , N.
  • the DU 174 transmits 318 the RRC reconfiguration message to UE 102.
  • the UE 102 transmits 320 a RRC reconfiguration complete message (e.g., an RRCReconfigurationComplete message) to the DU 174, which in turn transmits 322 a second DU-to-CU message including the RRC reconfiguration complete message to the CU 172.
  • the CU 172 performs security protection (e.g., integrity protection and/or encryption) on the RRC reconfiguration message.
  • the CU 172 generates a message authentication code for integrity (MAC-I) for the RRC reconfiguration message, encrypts the RRC reconfiguration message and the MAC-I to obtain an encrypted RRC reconfiguration message and an encrypted MAC-I, and transmits a PDCP PDU including the encrypted RRC reconfiguration message and encry pted MAC-I to the UE 102 via the DU 174 in the events 316 and 318.
  • MAC-I message authentication code for integrity
  • the UE 102 When the UE 102 receives the PDCP PDU from the CU 172 via the DU 174 (i.e., events 316 and 318), the UE 102 decrypts the encrypted RRC reconfiguration and encry pted MAC-I to obtain the RRC reconfiguration message and MAC-I and verifies whether the MAC-I is valid. If the UE 102 verifies the MAC-I is invalid, the UE 102 discards or ignores the RRC reconfiguration message. In some embodiments, the UE 102 may perform a RRC connection reestablishment procedure in response to the invalid MAC-I. Otherwise, if the UE 102 verifies the MAC-I is valid, the UE 102 may process the RRC reconfiguration.
  • the UE 102 refrains from applying (i.e., executing) the LTM DU configuration 1 until receiving a LTM command activating the LTM DU configuration 1 (e.g., events 330. 350, 398, 380, 430, or 450).
  • a LTM command activating the LTM DU configuration 1 e.g., events 330. 350, 398, 380, 430, or 450.
  • the events 308 (optional) and 310 are collectively referred to in FIG. 3 as an LTM preparation procedure 390 (also as a first procedure).
  • the events 316, 318, 320, and 322 are collectively referred to in FIG. 3 as a LTM configuration delivery 7 procedure 394.
  • the first CU-to-DU message is a UE Context Modification Request message
  • the first DU-to-CU message is a UE Context Modification Response message or UE Context Modification Required message.
  • the CU 172 may transmit a UE Context Modification Confirm message to the DU 174 in response to UE Context Modification Required message.
  • the second CU-to-DU message is a DL RRC Message Transfer message.
  • the second CU-to-DU message is a UE Context Modification Request message
  • the DU 174 may transmit a second DU-to-CU message (e.g., UE Context Modification Response message) to the CU 172 in response to the second CU-to-DU message.
  • a second DU-to-CU message e.g., UE Context Modification Response message
  • the CU 172 may include a reference LTM CU configuration in the RRC reconfiguration message 316 or the first container.
  • the CU 172 might generate the LTM CU configuration 1 (i.e.. non-reference LTM CU configuration) as a delta configuration to augment the reference LTM CU configuration.
  • the CU 172 might generate some or all of the LTM CU configuration(s) 2, . . . , N as delta configuration(s) to augment the reference LTM CU configuration.
  • the CU 172 includes the reference LTM CU configuration and does not include a non-reference LTM CU configuration.
  • the CU 172 includes the reference LTM CU configuration and/or the reference LTM DU configuration in an additional container (e.g., reference LTM configuration) and include the additional container in the RRC reconfiguration message 316.
  • the reference LTM CU configuration is different from the serving CU configuration. In some embodiments, a portion of the reference LTM CU configuration is the same as a portion of the serving CU configuration and the rest of the reference LTM CU configuration is different from the rest of the serving CU configuration. In yet other embodiments, the reference LTM CU configuration is the same as the serving LTM CU configuration.
  • the CU 172 includes, in the RRC reconfiguration message, a first LTM ID (referred to herein after as ID 1) for identifying the LTM DU configuration 1 or the element 1.
  • ID 1 a first LTM ID
  • the CU 172 includes the ID 1 in the first container or element 1.
  • the CU 172 assigns the ID 1.
  • the CU 172 may transmit the ID 1 to the DU 174, and the DU 174 associates the ID 1 with the LTM DU configuration 1.
  • the CU 172 in the first CU-to-DU message, includes the ID 1 and indicates the ID 1 is associated with the LTM DU configuration 1.
  • the CU 172 after receiving the first DU-to-CU message, transmits 312 a third CU-to-DU message including the ID 1 to the DU 174 instead of including the ID 1 in the first CU-to-DU message.
  • the CU 172 may include the LTM DU configuration 1 and the ID 1 and indicate the association between the ID 1 and LTM DU configuration 1.
  • the DU 174 may directly associate the ID 1 with the LTM DU configuration 1.
  • the CU 172 may include the cell ID 1 and the ID 1 (i.e., the first LTM ID) and indicate the association between the cell ID 1 and the ID 1.
  • the DU 174 may associate the ID 1 with the LTM DU configuration 1. based on the association between the cell ID 1 and the ID 1 and the association between the cell ID 1 and the LTM DU configuration 1 .
  • the CU 172 may include the LTM DU configuration 1, the cell ID 1, and/or the ID 1 and indicate the association between the ID 1, LTM DU configuration 1, and/or the cell ID 1.
  • the DU 174 may transmit 314 a third DU-to-CU message to the CU 172 in response to the third CU-to-DU message.
  • the third CU-to-DU message and third DU-to-CU message are UE Context Modification Request message and UE Context Modification Response message.
  • the events 312 (optional) and 314 (optional) are collectively referred to in FIG. 3 as a LTM ID assignment procedure 392 or a second procedure.
  • the CU 172 may include the ID 1, the cell ID 1, and/or the LTM DU configuration 1 in the second CU-to-DU message as described above.
  • the third CU-to-DU message may be omitted.
  • the DU 174 may include the ID 1 in the LTM DU configuration 1, first container, or element 1. Alternatively, DU 174 does not include the ID 1 in the LTM DU configuration 1, first container and/or element 1.
  • the CU 172 includes the reference LTM DU configuration in the first container.
  • the CU 172 includes the reference LTM DU configuration in a field of the first container, different from a field of the first container including the LTM DU configuration 1.
  • the CU 172 includes the reference LTM DU configuration in the RRC reconfiguration message 316 and outside the first container.
  • the CU 172 generates a third container (e.g., a field/IE) to include the first container and the reference LTM DU configuration and includes the third container in the RRC reconfiguration message 316.
  • DU 174 includes the reference LTM DU configuration in the first container.
  • DU 174 includes the reference LTM DU configuration in a field of the first container, different from a field of the first container including the LTM DU configuration 1 .
  • the DU 174 generates a fourth container (e.g., a field/IE) to include the first container and the reference LTM DU configuration and includes the fourth container in the first DU-to-CU message 310.
  • CU 172 includes the fourth container in the RRC reconfiguration message 316.
  • the CU 172 retrieves the reference LTM DU configuration and the LTM DU configuration 1 from the fourth container and includes the reference LTM DU configuration and the LTM DU configuration 1 as described above.
  • neither the CU 172 nor the DU 174 assign an ID to identify the reference LTM DU configuration. In some embodiments, neither the CU 172 nor the DU 174 assign an ID to identify the reference LTM CU configuration.
  • the LTM DU configuration 1 includes a plurality of configuration parameters for the UE 102 to communicate with the DU 174 on the first cell.
  • the plurality of configuration parameters includes physical layer configuration parameters (e.g., PhysicalCellGroupConfig lPfi MAC layer configuration parameters (s.g., MAC-CellGroupConfig IE) and/or RLC configuration parameters (e.g., RLC-BearerConfig IE(s)).
  • the plurality of configuration parameters includes a special cell configuration (e.g., SpCellConfig IE) and/or one or more SCell configurations (e.g., SCellConfig IE(s)).
  • the LTM DU configuration 1 is CellGroupConfig IE defined in 3GPP TS 38.331. In other embodiments, the LTM DU configuration 1 includes configuration parameters in the CellGroupConfig IE.
  • the LTM CU configuration 1 includes PDCP configuration parameters, measurement configuration parameters, and/or radio bearer configuration parameters.
  • the LTM CU configuration 1 includes aMeasConfig IE and/or a RadioBearerConfig IE defined in 3GPP TS 38.331 or includes configuration parameters in the MeasConfig IE and/or RadioBearerConfig IE.
  • the LTM DU configuration 1 includes LI measurement configuration 1 (e.g., a CSI-MeasConfig IE) and/or at least one transmission configuration indicator (TCI) state configuration.
  • the LTM CU configuration 1 includes the LI measurement configuration and/or the TCI state configuration(s) 1.
  • the LI measurement configuration includes at least one reference signal (RS) resource configuration 1 and/or at least one report configuration 1.
  • the RS resource configuration(s) 1 configures one or more RSs or one or more RS resources associated with the cell 1.
  • the RS(s) includes SSB(s) and/or CSI-RS(s).
  • the RS resource(s) includes SSB resource(s) and/or CSI-RS resource(s).
  • each of the RS resource configuration(s) 1 includes an RS resource configuration ID.
  • the RS resource configuration(s) 1 is/are (similar to) CSI-ResourceConfig IE(s).
  • the report configuration(s) 1 configures one or more UL resources (e.g., PUCCH resources or PUSCH resources) on cell 1 (i.e., the first cell) for the UE 102 to transmit measurement results.
  • each of the report configuration(s) 1 includes one or more RS resource configuration IDs identifying one or more RS resource configurations included in the RS resource configuration(s) 1 .
  • each of the TCI state configuration(s) 1 configures a TCI state that associates one or two DL RSs with a corresponding quasi-colocation (QCL) type. The DL RS(s) are associated with cell 1.
  • QCL quasi-colocation
  • the DU 174 includes the LI measurement configuration 1 and/or the TCI state configuration(s) 1 in a serving DU configuration 1 (e.g., non-LTM DU configuration).
  • the DU 174 includes the serving DU configuration in the first DU-to-CU message.
  • the DU 174 transmits an additional DU- to-CU message including the serving DU configuration to the CU 172.
  • the additional DU-to-CU message is a UE Context Modi fication Required message.
  • the CU 172 includes the serving DU configuration 1 in the RRC reconfiguration message 316, 318.
  • the CU 172 transmits another RRC reconfiguration message including the serving DU configuration to the UE 102 via the DU 174.
  • the DU 174 includes a random access configuration in the LTM DU configuration 1. In other embodiments, the DU 174 does not include a random access configuration in the LTM DU configuration 1. In some embodiments, if the cell 124A and first cell are not synchronized, the DU 174 determines to include the random access configuration in the LTM DU configuration 1. Otherwise, if cell 124A and first cell are synchronized, the DU 174 determines to not include the random access configuration in the LTM DU configuration 1. In other embodiments, if the DU 174 determines that the UE 102 has not synchronized in UL with the first cell, the DU 174 determines to include the random access configuration in the LTM DU configuration 1.
  • the DU 174 determines to not include the random access configuration in the LTM DU configuration 1. If the LTM DU configuration 1 includes the random access configuration, the UE 102 performs the random access procedure in event 332 in accordance with the random access configuration, as described below. Otherwise, if the LTM DU configuration 1 does not include the random access configuration or indicates the UE 102 to skip a random access procedure in LTM, the UE 102 skips or refrains from performing the random access procedure of the event 332 in response to the LTM DU configuration 1 excluding the random access configuration.
  • the DU 174 includes random access configuration parameters in the LTM DU configuration 1 and/or the reference LTM DU configuration regardless of whether the cell 124A and first cell are synchronized or not.
  • UE 102 performs the random access procedure in the event 332 in accordance with the random access configuration parameters, as described below.
  • the DU 174 determines to include, in the LTM DU configuration 1, a first indication configuring the UE 102 not to perform a random access procedure on the first cell. Otherwise, if cell 124A and first cell are not synchronized, the DU 174 determines to not include the first indication in the LTM DU configuration 1. In other embodiments, if the DU 174 determines that the UE 102 has synchronized in UL with the first cell, the DU 174 determines to include the first indication in the LTM DU configuration 1.
  • the DU 174 determines to not include the first indication in the LTM DU configuration 1. If the LTM DU configuration 1 includes the first indication, the UE 102 skips, or refrains from performing the random access procedure of the event 332 in accordance with or in response to the first indication. Otherwise, if the LTM DU configuration 1 does not include the first indication, the UE 102 performs the random access procedure in accordance with the random access configuration in the event 332, in response to the LTM DU configuration 1 excluding the first indication, as described below.
  • the DU 174 includes a reconfiguration with sync configuration (e.g.. ReconflgurationWithSync IE) in the LTM DU configuration 1 or special cell configuration. In other embodiments, the DU 174 does not include a reconfiguration with sync configuration (e.g., ReconflgurationWithSync IE) in the LTM DU configuration 1 or special cell configuration. In some embodiments, if the cell 124 A and first cell are not synchronized, the DU 174 determines to include the reconfiguration with sync configuration in the LTM DU configuration 1. Otherwise, if cell 124A and first cell are synchronized, the DU 174 determines to not include the reconfiguration with sync configuration in the LTM DU configuration 1.
  • a reconfiguration with sync configuration e.g.. ReconflgurationWithSync IE
  • the DU 174 determines to include the reconfiguration with sync configuration in the LTM DU configuration 1. Otherwise, if the DU 174 determines that the UE 102 has synchronized in UL with the first cell, the DU 174 determines to not include the reconfiguration with sync configuration in the LTM DU configuration 1. In some embodiments, if the LTM DU configuration 1 includes the reconfiguration with sync configuration, the UE 102 performs the random access procedure in the event 332 as described below, in response to or in accordance with the reconfiguration with sync configuration.
  • the DU 174 includes a cell ID (i.e., cell ID 1) of cell 1 (i.e., the first cell) in the LTM DU configuration 1.
  • the cell ID 1 may be a PCI.
  • the cell ID 1 is a CGI.
  • the cell ID 1 included in the LTM DU configuration l is a PCI, while the cell ID 1 included in the first CU-to-DU message is a CGI.
  • the LTM DU configuration 1 includes a cell index 1 indexing the cell ID 1 or the first cell.
  • Cell index 1 is not a cell ID.
  • the cell index takes fewer bits than the cell ID.
  • the CU 172 sets the cell index 1 to a value and includes the cell index 1 in the first CU-to-DU message of the event 308.
  • the first BS 104 determines to prepare additional cell(s) (i.e., cell(s) 2, ... , N) of the first BS 104 for LTM for the UE 102.
  • the first BS 104 determines to prepare the additional cell(s) for LTM for the UE 102 because the at least one measurement report indicates that the additional cell(s) could be used by the first BS 104 to communicate with the UE 102.
  • the additional cell(s) may include the cell 124C and/or cell(s) other than the cells 124A, 124B and 124C.
  • the CU 172 determines to prepare the particular cell for LTM for the UE 102.
  • the DU 174 determines to prepare the particular cell for LTM for the UE 102.
  • the respective predetermined threshold(s) for the additional cells may be different from the first predetermined threshold. In another embodiment, the respective predetermined threshold(s) for the additional cell(s) may be the same as the first predetermined threshold. In some embodiments, the respective predetermined thresholds for the additional cells may be the same or different. Alternatively, the first BS 104 determines to prepare the additional cell(s) for the UE 102 regardless of whether a measurement report is received from the UE 102 or not.
  • the CU 172 determines to prepare the additional cell(s)
  • the CU 172 initiates and performs at least one additional LTM preparation procedure (LTM preparation procedure(s)) with the DU 174 to prepare the additional cell(s) for LTM, where each of the LTM preparation procedure(s) is similar to the procedure 390.
  • the DU 174 determines to prepare the additional cell(s)
  • the DU 174 initiates and performs at least one additional LTM preparation procedure (LTM preparation procedure(s)) with the CU 172 to prepare the additional cell(s) for LTM, where each of the LTM preparation procedure(s) is similar to the procedure 390.
  • the CU 172 and DU 174 perform LTM preparation procedure(s) 2. .... N to prepare the cell(s) 2, . . . , N. respectively, similar to the procedure 390.
  • the CU 172 may include the cell ID(s) 2, ... , N in CU-to-DU message(s) 2, ... , N in the LTM preparation procedure(s) 2, ... , N, respectively, similar to the first CU-to-DU message.
  • the DU 174 In the LTM preparation procedure(s) 2, . . . , N, the DU 174 generates LTM DU configuration(s) 2, . .. , N configuring the cell(s) 2. . . . .
  • N includes the LTM DU configuration(s) 2, . .. , N in DU-to-CU message(s) 2, . . . , N, respectively, as descnbed for the LTM DU configuration 1.
  • the DU 174 receives the CU-to-DU message(s) 2, . .. , N
  • the DU-to-CU message(s) 2, . . . , N responds to the CU-to-DU message(s) 2, . .. , N, respectively.
  • “N”’ is an integer larger than one.
  • “N” is 2, 3, 4, 5. 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16.
  • the CU 172 and DU 174 perform a single LTM preparation procedure (i.e., the LTM preparation procedure 390) to prepare the cell(s) 1, 2, ... , N.
  • the DU 174 includes the LTM DU configuration(s) 1, 2, . . . , N for the cell(s) 1, 2, ... , N, respectively in the first DU-to-CU message.
  • the DU 174 may include the cell ID(s) 1, 2, ... , N, respectively, associated with the LTM DU configuration(s) 1, 2, . . . , N to indicate that the LTM DU configuration(s) 1, 2, . . .
  • N are configured for the cell ID(s) 1, 2, .. . , N, respectively.
  • the CU 172 determines to perform the LTM preparation procedure 390, the CU 172 includes the cell ID(s) 1, 2, . . . , N in the first CU-to-DU message to request the DU 174 to prepare the cell(s) 1, 2, ..., N, respectively, for LTM.
  • the CU 172 After receiving the LTM DU configuration(s) 2, ... , N from the DU 174, the CU
  • the CU 172 may include the LTM DU configuration(s) 2, , N in the first container.
  • the CU 172 may include the LTM DU configuration(s) 2, . . . , N in element(s) 2, .. . , N, respectively, and includes the element(s) 2, .. . , N in the first container.
  • the CU 172 includes, in the RRC reconfiguration message, LTM ID(s) (i.e., ID(s) 2, .. . , N) for identifying the LTM DU configuration(s) 2, . . . , N, respectively.
  • the CU 172 includes the ID(s) 2, . . .
  • the CU 172 may include the ID(s) 2, .. . . N and LTM DU configuration(s) 2, . . . , N in the element(s) 2. .... N in the first addition or modification list.
  • the CU 172 assigns the ID(s) 2, . . . , N for the LTM DU configuration(s) 2, ... , N, respectively.
  • the CU 172 receives the ID(s) 2, .. . , N from the DU 174 in the first DU-to-CU message of the procedure 390.
  • the CU 172 receives from the DU 174 the ID(s) 2, . . . , N in the DU-to-CU message(s) 2, .. . , N of the LTM preparation procedure(s) 2. . . . . N, respectively.
  • the CU 172 may perform an LTM ID assignment procedure with the DU 174 for each of the LTM DU configuration(s) 2, . .. , N, similar to the procedure 392.
  • the CU 172 may include the ID(s) 2, . . . , N and the LTM DU configuration(s) 2, ... , N in the third CU-to-DU message and indicate the association between the ID(s) 2. . . . , N and the LTM DU configuration(s) 2, . . . , N, respectively.
  • the DU 174 may associate the LTM DU configuration(s) 2, . . . , N with the ID(s) 2, . .
  • the CU 172 may include the cell ID(s) 2, . . . , N and the ID(s) 2, .. . , N in the third CU-to-DU message and indicate the association between the cell ID(s) 2, ... , N and the ID(s) 2, .. . , N, respectively.
  • the DU 174 may associate the LTM DU configuration(s) 2, ... , N with the ID(s) 2, ... , N, respectively, based on the association between the cell ID(s) 2. . .. . N and the ID(s) 2, . . . , N and the association between the cell ID(s) 2, .. .
  • the CU 172 may include the ID(s) 2, . . . , N, the cell ID(s) 2, . . . , N and/or the LTM DU configuration(s) 2, . . . , N in the second CU-to-DU message as described above.
  • the third CU-to-DU message may be omitted.
  • the CU 172 may include the ID(s) 2, . .. , N in the first CU-to-DU message and indicate the ID(s) 2, . .. , N is/are respectively associated with the cell ID(s) 2, ...
  • the DU 174 includes the ID(s) 2, . . . , N in the LTM DU configuration(s) 2, .. . , N.
  • the CU 172 does not include the ID(s) 2, ... , N in the RRC reconfiguration message, first container, and/or element(s) 2, . .. , N.
  • the DU 174 assigns the ID(s) 2, .. . , N.
  • the DU 174 includes the ID(s) 2, . . . , N in the first DU-to-CU message of the procedure 390.
  • the DU 174 includes the ID(s) 2. . .. , N in the DU- to-CU message(s) 2. .... N of the LTM preparation procedure(s) 2, ... , N.
  • the CU 172 may include the ID(s) 2, .. . , N in the RRC reconfiguration message.
  • the DU 174 includes the ID(s) 2, .. .
  • the CU 172 does not include an ID (e.g.. LTM ID) identifying each of the LTM DU configuration(s) 2, ... , N in the RRC reconfiguration message, first container, and/or element 1 discussed above.
  • ID e.g.. LTM ID
  • the CU 172 may generate a second container including the LTM DU configuration(s) 2, . . . , N or element(s) 2, . .. , N instead of using the first container.
  • the CU 172 then transmits an additional RRC reconfiguration message including the second container to the UE 102 via the DU 174, substantially similar to the events 316 and 318.
  • UE 102 transmits an additional RRC reconfiguration complete message to the CU 172 via the DU 174, similar to the events 320 and 322.
  • the second container may be a second addition or modification list (e.g., Itm-ConfigToAddModList field, LTM-ConfigToAddModList IE, Itm- CandidateConflgToAddModList field, or LTM-CandidateConflgToAddModList IE), and each of the element(s) 2, ... , N may be an addition or modification IE (e.g., Itm-ConflgToAddMod field, LTM-ConfigToAddMod IE, Itm-CandidateConfigToAddMod field, or LTM- CandidateConfigToAddMod IE).
  • the UE 102 may store the second addition or modification list together with the first addition or modification list, e.g., as a variable in its RAM.
  • the DU 174 includes cell ID(s) 2, . . . , N in the LTM DU configuration(s) 2, ... , N to identify the cell(s) 2, ... , N, respectively.
  • each of the cell ID(s) 2, .. . , N is a PCI.
  • the LTM DU configuration(s) 2, . .. , N includes cell index(es) 2, .. . , N indexing the cell ID(s) 2, . . . , N or the cell(s) 2, . . . , N, respectively.
  • the CU 172 prepares the cell(s) 2, . ..
  • the CU 172 may set the cell index(es) 2, ... , N to different value(s) and include the cell index(es) 2, ... , N in the first CU-to CU-to-DU message of the event 308.
  • the CU 172 may set the cell index(es) 2, .. . , N to different values and include the cell index(es) 2, . . . , N in CU-to-DU message(s) of the additional LTM preparation procedure(s).
  • the CU 172 sets the cell index(es) 1, , N to different values.
  • the cell ID(s) 1 , . .. , N in the LTM DU configuration(s) 1, . . . , N are different from the cell ID(s) 1, . .. , N in the CU-to-DU message(s) described above.
  • each of the LTM DU configuration(s) 1, .. . , N includes physical configuration parameters, MAC configuration parameters, RLC configuration parameters and/or LI measurement configuration(s).
  • each of the LTM DU configuration(s) 1. ... . N may be a CellGroupConflg IE as defined in 3GPP TS 38.331.
  • each of the LTM DU configuration(s) 1, . . . , N include configuration parameters included in a CellGroupConfig IE as defined in 3GPP TS 38.331.
  • the plurality of configuration parameters in each of the LTM DU configuration(s) include a particular special cell configuration (e.g., SpCellConfig IE) and/or one or more SCell configurations (e.g., SCellConfig IE(s)).
  • the LTM DU configuration(s) 1, ... , N are CellGroupConfig IE(s) defined in 3GPP specification 38.331.
  • the LTM DU configuration(s) 1, ... , N include configuration parameters in the CellGroupConfig IE.
  • the CU 172 may include one or more additional LTM CU configurations in at least one of the element(s) 2, . . . , N. the first container, or the second container.
  • Each of the additional LTM CU configurations are associated with a particular LTM DU configuration of the LTM DU configuration(s) 2, . .. , N. Examples and embodiments of the additional LTM CU configurations are similar to the LTM CU configuration 1.
  • the CU 172 determines to release the LTM DU configuration M of the LTM DU configuration(s) 1. .... N (or the element M of the element(s) 1 , . .. , M, with 1 ⁇ M ⁇ N). In response to this determination, the CU 172 transmits an RRC reconfiguration message to the UE 102 via the DU 174 to instruct the UE 102 to release the LTM DU configuration M or element M. In one embodiment, the CU 172 generates a release list including the ID (i.e., LTM ID) M for releasing the LTM DU configuration M or element M and includes the release list in the RRC reconfiguration message.
  • ID i.e., LTM ID
  • UE 102 releases the LTM DU configuration M or element M and transmits an RRC reconfiguration complete message to the CU 172 via the DU 174.
  • the CU 172 transmits a CU-to- DU message to the DU 174 to instruct the DU 174 to release the LTM DU configuration M.
  • the CU 172 may include the cell ID M or the ID (i.e., LTM ID) M in a release indication (e.g., a field or IE) in the CU-to- DU message.
  • the DU 174 releases the LTM DU configuration M and transmits a DU-to-CU message to the CU 172.
  • the CU-to-DU message and DU- to-CU message are a UE Context Modification Request message and a UE Context Modification Response message, respectively.
  • DU 174 determines to release the LTM DU configuration K.
  • the DU 174 transmits a DU-to-CU message to the CU 172 to release the LTM DU configuration K.
  • the DU 174 may include the cell ID K or the ID (i.e., LTM ID) K in a release indication (e.g., a field or IE) in the DU-to-CU message, with 1 ⁇ K ⁇ N.
  • the CU 172 After (e.g., in response to) receiving the DU-to-CU message, the CU 172 generates a release list including the ID (i.e., LTM ID) K to release the LTM DU configuration K or element K and transmits an RRC reconfiguration message including the release list to the UE 102 via the DU 174. In response, the UE 102 releases the LTM DU configuration K or element K and transmits a RRC reconfiguration complete message to the UE 102 via the DU 174.
  • the CU 172 maytransmit a CU-to-DU message to the DU 174 in response to the DU-to-CU message.
  • the DU-to-CU message and CU-to-DU message are a UE Context Modification Required message and a UE Context Modification Confirm message, respectively.
  • the UE 102 After receiving the RRC reconfiguration in event 318 or transmitting the RRC reconfiguration complete message in event 320. the UE 102 transmits 324 at least one measurement report to the DU 174, similar to the event 304.
  • the DU 174 may transmit 326 a DU-to-CU message including the at least one measurement report to the CU 172, similar to the event 306.
  • the DU 174 does not transmit the at least one measurement report to the CU 172.
  • the at least one measurement report of the event 324 includes LI measurement report(s) or L3 measurement report(s), as described above for the event 304.
  • the UE 102 transmits 324 the at least one measurement report on PUCCH(s) and/or PUSCH(s) to the DU 174, similar to the event 304. In other embodiments, the UE 102 transmits 324 at least one MAC CE including the at least one measurement report to the DU 174, similar to the event 304. In some embodiments, UE 102 does not transmit the LI measurement report(s) as an RRC message(s) to the DU 174.
  • UE 102 transmits 324 the at least one measurement report to DU 174 in accordance with at least one measurement configuration.
  • the at least one measurement configuration configures the UE 102 to perform measurements and report measurement results.
  • the CU 172 transmits the at least one measurement configuration to the UE 102 via the DU 174.
  • the CU 172 may transmit one or more RRC messages (e.g., RRCReconfiguration message(s)) including the at least one measurement configuration to the UE 102 via the DU 174 in the event 302 and/or 316 and/or after the event 306 or 316.
  • the one or more RRC messages may or may not include the RRC reconfiguration message of event 316.
  • the UE 102 performs measurements on one or more reference signals.
  • the one or more reference signals may include one or more SSBs and/or one or more CSI-RSs.
  • the UE 102 obtains the at least one LI measurement result and/or at least one L3 measurement result from the measurements and includes the at least one LI measurement result and/or at least one L3 measurement result in the at least measurement report of the event 324.
  • the DU 174 transmits the one or more reference signals on the cell 124A, the cell 1 and/or the cell(s) 2, . . . , N.
  • the one or more reference signals may be CSI-RS(s) or SSB(s).
  • the at least one measurement configuration includes L3 measurement configuration(s) (e.g., MeasConflg IE(s)), as described for the event 304.
  • the at least one measurement configuration includes or is LI measurement configuration(s), as described above.
  • the LI measurement configuration(s) may be CSI-MeasConfig IE(s) defined in 3GPP TS 38.331.
  • the LI measurement configuration(s) may include RS resource configuration(s) and/or report configuration(s).
  • UE 102 transmits 324 the LI measurement report(s) on UL resources (e g., PUCCH resources or PUSCH resources) to the DU 174 in accordance with the report configuration(s).
  • the DU 174 receives the LI measurement report(s) on the UL resources in accordance with the report configuration(s).
  • the report configuration(s) are or are similar to CSI-ReportConflg IE(s).
  • each of the report configuration(s) is a new RRC IE.
  • (each of) the report configuration(s) configures periodically reporting and/or event-triggered reporting of the LI measurement result(s).
  • the LI measurement report(s) is/are CSI report(s).
  • the LI measurement report(s) is/are MAC CE(s).
  • each of the measurement report(s) includes one or more RS resource indicators and/or one or more quantized measurement values.
  • the UE 102 performs measurements on the RS(s) or the RS resource(s) in accordance with the RS resource configuration(s) and/or the report configuration(s) and obtains the quantized measurement values from the measurements.
  • the RS resource indicator(s) indicates the RS(s) or a RS resource(s) where the UE 102 perform measurements or obtains the quantized measurement values.
  • the RS resource indicator(s) includes one or more SSB resource indicators (SSBRI(s)) and/or one or more CSI-RS resource indicators (CRI(s)).
  • the quantized measurement values might include one or more Ll-RSRP values and/or one or more Ll- SINR values.
  • the at least one measurement configuration includes new-type measurement configuration(s) (e.g., LTM measurement configuration(s)).
  • the new- type measurement configuration may be newly defined in a 3GPP TS.
  • the new-type measurement configuration(s) includes reference signal resource configuration(s) configuring resources where the DU 174 transmits reference signal(s).
  • the reference signal resource configuration(s) include CSI-RS(s) and/or SSB(s).
  • the reference signal resource configuration(s) is/are CSI-ResourceConflg IE(s).
  • the new-type measurement configuration(s) include measurement report configuration(s), as described above.
  • the UE 102 transmits the measurement report(s) on PUCCH(s) or MAC CE(s) to the DU 174 in accordance with the measurement report configuration(s).
  • DU 174 receives the measurement report(s) on PUCCH(s) or MAC CE(s) in accordance with the measurement report configuration(s).
  • the measurement report(s) may be LI measurement report(s) or new-type measurement report(s) (e.g., LTM measurement report(s)).
  • the new-type measurement configuration includes configuration parameters newly defined in a 3 GPP TS.
  • the DU 174 After (e.g., in response to) receiving the at least one measurement report in the event 324, the DU 174 generates a first LTM command to activate the LTM DU configuration 1 (i.e., the first LTM command commands the UE 102 to apply the LTM DU configuration 1 or to perform a serving cell change to the cell 1). The DU 174 then transmits 330 the first LTM command to UE 102. In some embodiments, the DU 174 transmits the first LTM command on cell 124A to the UE 102. In other embodiments, the DU 174 transmits the first LTM command on the cell 124D to the UE 102.
  • the DU 174 may include the ID 1 in the first LTM command to indicate the LTM DU configuration 1 or element 1, and the UE 102 determines (e.g., identifies) the LTM DU configuration 1 or element 1 in accordance with the ID 1.
  • the DU 174 may include the cell index 1 indexing the cell ID 1 in the first LTM command.
  • UE 102 determines (e.g., identifies) the LTM DU configuration 1 or element 1, based on cell index 1.
  • the UE 102 retrieves the cell index 1 from the LTM DU configuration 1 or element 1, and establishes an association 1 between the cell index 1 and the LTM DU configuration 1 or element 1.
  • UE 102 decodes the LTM DU configuration 1 or element 1 to obtain the cell index 1, before receiving the first LTM command.
  • the UE 102 identifies the LTM DU configuration 1 or element 1 in accordance with the cell index 1 and the association 1.
  • the UE 102 Before receiving the first LTM command, the UE 102 retrieves the cell index(es) 2, .. . , N from the LTM DU configuration(s) or element(s) 2, . . . , N and establishes association(s) 2, . . . , N between the cell index(es) 2, . .. , N and the LTM DU configuration(s) or element(s) 2, ... , N, respectively. In other words, the UE 102 decodes the LTM DU configuration(s) or element(s) 2, .. . , N to obtain the cell index(es) 2, . .. , N, before receiving the first LTM command.
  • the DU 174 may include the cell ID 1 in the first LTM command.
  • UE 102 determines (e.g., identifies) the LTM DU configuration 1 or element 1, based on the cell ID 1.
  • the UE 102 retrieves the cell ID 1 from the LTM DU configuration 1 or element 1, and establishes an association 1 between the cell ID 1 and the LTM DU configuration 1 or element 1.
  • the UE 102 decodes the LTM DU configuration 1 or element 1 to obtain the cell ID 1, before receiving the first LTM command.
  • the UE 102 identifies the LTM DU configuration 1 or element 1 in accordance with the cell ID 1 (received in the first LTM command) and the association 1.
  • the UE 102 retrieves the cell ID(es) 2, .. . , N from the LTM DU configuration(s) or element(s) 2, . . . , N and establishes association(s) 2, . . . , N between the cell ID(es) 2, .. . , N and the LTM DU configurati on(s) or element(s) 2, ... , N, respectively.
  • the UE 102 decodes the LTM DU configuration(s) or element(s) 2, .
  • the DU 174 may include a bit map in the first LTM command to activate the LTM DU configuration 1, instead of the ID 1 or cell index 1.
  • the number of bits in the bit map is larger than or equal to “N”.
  • bit 1 , . . . , N corresponds to the cell index(es) 1, , N, the ID(s) 1. ... . N, the LTM DU configuration(s) 1, . .. , N or the element(s) 1, . . .
  • bit 1 a corresponding bit in the bit map to a first value to indicate the cell index 1, the ID 1, the LTM DU configuration 1, or the element 1.
  • bit 0. . .. . N-l corresponds to the cell index(es) 1 , . . . , N, the ID(s) 1, ... , N, the LTM DU configuration(s) 1, ... , N, or the element (s) 1, ...
  • the DU 174 sets a corresponding bit (e.g., bit 0) in the bit map to a first value to indicate the cell index 1, the ID 1 the LTM DU configuration 1, or the element 1.
  • the UE 102 may determine the cell index 1. the ID 1 LTM DU configuration 1, or element 1 in accordance with the bit 0 set to the first value in the bit map.
  • the DU 174 sets the remaining bits in the bit map to a second value to indicate that the rest of the LTM DU configuration(s) 1, . . . , N is/are not activated.
  • the first value is one and the second value is zero. In other embodiments, the first value is zero and the second value is one.
  • the DU 174 may set the corresponding bit (e.g., bit L or bit L-7) in the bit map to the first value and set the remaining bits to the second value, where 1 ⁇ L ⁇ N. In some embodiments, the DU 174 sets at most one bit in the bit map to the first value.
  • the UE 102 After determining or identifying the LTM DU configuration 1 or element 1, the UE 102 then applies the LTM DU configuration 1 and/or LTM CU configuration, after (e.g., in response to) receiving the first LTM command.
  • the at least one measurement report (e.g., LI measurement report(s) or new-type measurement report(s)) of the event 324 includes at least one measurement result for the first cell (i.e., cell 1), TRP(s) of the first cell or reference signal(s) transmitted on the first cell.
  • the reference signal(s) may be CSI-RS(s) or SSB(s).
  • DU 174 determines to activate the LTM DU configuration 1 or transmit the first LTM command, based on the at least one measurement result. In some embodiments, DU 174 determines to activate the LTM DU configuration 1 because, when, or if the at least one measurement result is above a second predetermined threshold.
  • the at least one measurement result includes Ll -RSRP value(s), Ll -RSRQ value(s), and/or Ll -SINR value(s). In other embodiments, the at least one measurement result includes RSRP value(s), RSRQ value(s), and/or SINR value(s) for the new-type measurement report(s).
  • the second predetermined threshold is different from the first predetermined threshold. In one embodiment, the second predetermined threshold is larger than the first predetermined threshold. In this case, the at least one measurement result indicates that the first cell is suitable for communication with the UE 102. In another embodiment, the second predetermined threshold is equal to the first predetermined threshold.
  • the at least one measurement result indicates that the first cell has been continuously above the second predetermined threshold or the first predetermined threshold. This indicates that the first cell is suitable for communication with UE 102.
  • DU 174 determines to activate the LTM DU configuration 1 in response to that signal strength or quality of the first cell being above the second predetermined threshold, for the UE 102.
  • the at least one measurement report of the event 326 indicates that signal strength or quality of the first cell has been continuously above the second predetermined threshold or the first predetermined threshold. This also indicates that the first cell is suitable for communication with UE 102.
  • the CU 172 determines to activate the LTM DU configuration 1 in response to that signal strength or quality of the first cell is above the second predetermined threshold.
  • the CU 172 transmits 328 a fourth CU-to-DU message to the DU 174 to activate the LTM DU configuration 1 or trigger a serving cell change to the cell 1 for the UE 102.
  • the CU 172 includes the ID 1 in the fourth CU-to-DU message.
  • the CU 172 may include the ID 1 in the fourth CU-to-DU message.
  • DU 174 may determine to activate the LTM DU configuration 1 in accordance with the ID 1.
  • the fourth CU-to-DU message and fourth DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Response message, respectively.
  • the fourth CU-to-DU message and/or fourth DU-to-CU message are new interface messages, e.g., Fl application protocol (F1AP) messages defined in 3GPP TS 38.473.
  • Fl application protocol F1AP
  • the DU 174 When or in response to determining to activate the LTM DU configuration 1 or transmit the first LTM command 330, the DU 174 might transmit 329 to the CU 172 a DU- to-CU message indicating LTM (being) executed.
  • the DU 174 includes the cell ID 1 or the ID 1 (i.e., LTM ID) in the DU-to-CU message 329 to indicate that the DU 174 is to activate the LTM DU configuration 1 or trigger a fast serving cell change (i.e., an LTM serving cell change).
  • the DU may transmit the DU-to-CU message 329 to the CU 172 before or after transmitting the LTM command 330.
  • the first LTM command is a MAC CE included in a MAC PDU that the UE 102 receives from the DU 174 in the event 330.
  • the MAC CE may be a new MAC CE defined in 3GPP TS 38.321.
  • the DU 174 includes a subheader identifying the new MAC CE in the MAC PDU and the UE 102 identifies the new MAC CE in the MAC PDU in accordance with the subheader.
  • the subheader may include a logical channel ID or extended logical channel ID defined in a 3 GPP TS to identify the new MAC CE. For example, the logical channel ID or extended logical channel ID are newly defined in 3GPP TS 38.321.
  • the first LTM command is a DCI that the UE 102 receives on a PDCCH from the DU 174 in the event 330.
  • the DU 174 generates a CRC for the DCI, scrambles the CRC with a first C-RNTI of the UE 102, and transmits the DCI and scrambled CRC on the PDCCH in event 330.
  • a format of the DCI may be an existing DCI format defined in a 3GPP TS (e.g., TS 38.212).
  • the format of the DCI may be a new DCI format defined in a 3 GPP TS.
  • the DU 174 does not perform security protection (e.g., integrity protection and/or encry ption) on the first LTM command. This speeds up processing the first LTM command in the UE 102 because the UE 102 does not perform security check (e.g.. decryption and/or integrity check) on the first LTM command.
  • security protection e.g., integrity protection and/or encry ption
  • security check e.g. decryption and/or integrity check
  • the UE 102 may transmit 331 an acknowledgement to the DU 174 on the cell 124A or cell 124D to indicate that the UE 102 receives the first LTM command.
  • the acknowledgement is a HARQ ACK.
  • the acknowledgement is a MAC CE.
  • the MAC CE is an existing MAC CE defined in 3GPP TS 38.321.
  • the MAC CE is a new MAC CE defined in 3GPP TS 38.321.
  • the acknowledgement is a PUCCH transmission.
  • the CU 172 transmits 316 the RRC reconfiguration message in response to the L3 measurement report 306 for the first cell (i. e. , procedures 390 and 392 are not performed in this embodiment).
  • the CU 172 may transmit a first RRC reconfiguration message including the L3 measurement configuration (e.g., aMeasConflg IE) to the UE 102 before the event 306.
  • the DU 174 transmits 330 the first LTM command in response to the LI measurement report(s) 324 for the first cell.
  • the CU 172 may transmit a second RRC reconfiguration message including the LI or new-type measurement configuration(s) to the UE 102.
  • the first and second RRC reconfiguration messages may be the same message (i.e., the same instance).
  • the first and second RRC reconfiguration messages are different messages.
  • the second RRC reconfiguration message is the RRC reconfiguration message of event 316.
  • the second RRC reconfiguration message is different from the RRC reconfiguration message of event 316.
  • the UE 102 accesses 332 the first cell.
  • UE 102 identifies the LTM DU configuration 1 in accordance with the ID 1, the cell ID 1, or the cell index 1 received in the first LTM command and applies the LTM DU configuration 1 to communicate with the DU 174 on the first cell.
  • the UE 102 disconnects from the cell 124A, after (e.g., in response to) receiving the first LTM command or after transmitting 331 the acknowledgement.
  • the UE 102 stops communicating on the cell 124A after (e.g., in response to) receiving 330 the first LTM command or transmitting 331 the acknowledgement.
  • the UE 102 accesses the first cell by performing a random access procedure on the first cell with the DU 174, in response to receiving the first LTM command. In other embodiments, the UE 102 skips a random access procedure and transmits the first transmission (e.g., a PUSCH transmission or a PUCCH transmission) on the first cell to the DU 174. after (e.g., in response to) receiving the first LTM command.
  • the first transmission e.g., a PUSCH transmission or a PUCCH transmission
  • the DU 174 configures the access of the UE 102 to the first cell, including whether the UE 102 performs a random access procedure, in the LTM DU configuration 1.
  • the UE 102 determines whether to perform a random access procedure on the first cell in accordance with the LTM DU configuration 1. If the LTM DU configuration 1 configures the UE 102 to perform a random access procedure, the UE 102 performs a random access procedure on the first cell in event 332, in order to connect to the first cell.
  • the LTM DU configuration 1 includes a reconfiguration with sync configuration (e.g., ReconfigurationWithSync IE) to configure that the UE 102 performs a random access procedure when the UE 102 receives a LTM command for the first cell.
  • the DU 174 configures the UE 102 to skip the random access procedure for a LTM serving cell change to the first cell.
  • the UE 102 after receiving the first LTM command, the UE 102 skips the random access procedure and transmits the first transmission (e.g.. a PUSCH transmission or a PUCCH transmission) on the first cell to the DU 174 in event 332.
  • the DU 174 excludes a reconfiguration with sync configuration in the LTM DU configuration 1 to configure the UE 102 skipping a random access procedure for a LTM serving cell change to the first cell.
  • the LTM DU configuration 1 includes the reconfiguration with sync configuration or the random access configuration.
  • the DU 174 configures whether the UE 102 performs a random access procedure on the first cell in a LTM command.
  • UE 102 determines whether to perform the random access procedure on the first cell in event 332 in accordance with the first LTM command.
  • the DU 174 includes, in the first LTM command, an indication (e.g., a field) indicating skipping a random access procedure.
  • the UE 102 In response to receiving the timing advance value or the first LTM command including the timing advance value, the UE 102 skips a random access procedure and transmits the first transmission on the first cell to access the first cell, using the timing advance value.
  • the DU 174 excludes, in the first LTM command, a timing advance value to configure the UE 102 to perform a random access procedure.
  • the UE 102 performs a random access procedure on the first cell to access the first cell.
  • the random access procedure is a four-step random access procedure. In other embodiments, the random access procedure is a two-step random access procedure. In some embodiments, the random access procedure is a contention-free random access procedure. In other embodiments, the random access procedure is a contention-based random access procedure. In cases where the random access procedure is a four-step random access procedure, UE 102 transmits a Message 3 including a UE identity to the DU 174 via the first cell in the random access procedure. The DU 174 transmits a contention resolution message (e g., a Message 4) to the UE 102 in response to the Message 3.
  • a contention resolution message e g., a Message 4
  • UE 102 transmits a message A including the UE identity to the DU 174 via the first cell in the random access procedure.
  • the DU 174 transmits a contention resolution message (e.g., message B) to the UE 102 in response to message A.
  • the UE 102 determines that the UE 102 successfully completes the random access procedure (i.e.. the UE 102 successfully accesses the first cell).
  • the LTM DU configuration 1 includes a second C-RNTI and the UE identity is the second C-RNTI of the UE 102.
  • the contention resolution message is a PDCCH transmission addressed to the second C-RNTI.
  • the LTM DU configuration 1 does not include a C-RNTI
  • the UE identity is the first C-RNTI.
  • the contention resolution message is a PDCCH transmission addressed to the first C-RNTI.
  • the random access procedure is a contention free random access procedure.
  • the UE 102 transmits the dedicated random access preamble to the DU 174 via the first cell.
  • the UE 102 determines that the UE 102 successfully completes the random access procedure (i.e., the UE 102 successfully accesses the first cell).
  • the DU 174 configures the UE 102 to perform a random access procedure on the first cell as described above, the DU 174 will detect that the UE 102 has accessed the first cell when the DU 174 receives message 3. message A, or the dedicated preamble in the random access procedure. If the DU 174 configures the UE 102 to skip a random access procedure, the DU 174 will detect that the UE 102 has accessed the first cell when the DU 174 receives the first transmission.
  • the UE 102 transmits the first transmission (e.g., the PUSCH transmission) on the first cell using an UL grant.
  • the first LTM command includes the UL grant.
  • the UE 102 receives a first DCI including the UL grant on a PDCCH on the first cell.
  • the UE 102 attempts to receive the first DCI or the UL grant by monitoring one or more PDCCHs on the first cell in accordance with the LTM DU configuration 1, when the UE 102 switches to the first cell in response to the first LTM command.
  • the UE 102 While monitoring one or more PDCCHs on the first cell, the UE 102 receives the first DCI and a CRC of the first DCI on the PDCCH. In the case that the LTM DU configuration 1 includes the second C-RNT, the UE 102 determines that the first DCI was sent for the UE 102, using the CRC and the second C-RNTI. In the case that the LTM DU configuration 1 does not include the second C-RNT, the UE 102 determines that the first DCI was sent for the UE 102, using the CRC and the first C-RNTI.
  • the CU 172 transmits at least one first TCI state configuration to the UE 102 via the DU 174.
  • each of the first TCI state configuration(s) configures a TCI state for the UE 102 to transmit and/or receive data and/or control signal on the first cell.
  • Each TCI state associates one or two DL RSs with a corresponding QCL type and the DL RS(s) might be associated with a particular cell of the cell(s) 1, ... , N.
  • the CU 172 receives 310 a DU-to-CU message including the first TCI state configuration(s) from the DU 174 and transmits 316, 318 an RRC message, including the first TCI state configuration(s), to the UE 102 via the DU 174.
  • the DU 174 includes the first TCI state configuration(s) in a serving DU configuration (e.g., CellGroupConfig IE) and includes the serving DU configuration in the DU-to-CU message.
  • the DU 174 includes the LTM DU configuration 1 in a first interface protocol lE/field in the message 312 and includes the serving DU configuration in a second interface protocol lE/field in the DU-to-CU message.
  • the first interface protocol lE/field is defined as part of a format of the DU-to-CU message.
  • CU 172 includes the serving DU configuration in the RRC message. In some embodiments, the CU 172 refrains from including the serving DU configuration in a container for LTM (e.g., the first container). In other embodiments, the CU 172 includes the first TCI state configuration(s) in an element for LTM, an addition or modification list for LTM, or a container, similar to the element 1, the first addition, or modification list, or the first container respectively.
  • the RRC message is the RRC reconfiguration message 316, 318 or another RRC reconfiguration message (not shown in FIG. 3).
  • the DU-to-CU message is the message 312, the message 314, a UE Context Modification Response message, or a UE Context Modification Required message.
  • the DU 174 also includes the first TCI state configuration(s) in the LTM DU configuration 1. In other embodiments, the DU 174 refrains from including the first TCI state configuration(s) in the LTM DU configuration 1.
  • the first interface protocol lE/field is a first Fl AP lE/field and the second interface protocol lE/field is a second F1AP lE/field.
  • one of the first Fl AP lE/field and the second Fl AP lE/field is a Fl AP CellGroupConfig lE/field and the other is not the Fl AP CellGroupConfig lE/field.
  • the DU 174 includes the first F1AP lE/field in a DU to CU RRC Information IE in the message 312 and includes the second Fl AP lE/field in the DU to CU RRC Information IE in the DU- to-CU message.
  • neither the first Fl AP lE/field nor the second F 1 AP IE is a Fl AP CellGroupConfig lE/field.
  • the second Fl AP lE/field is the DU to CU RRC Information IE and the first Fl AP lE/field is a new IE specific for including a LTM DU configuration.
  • the UE 102 monitors one or more PDCCHs on the first cell using some or all of the first TCI state configuration(s).
  • each of the first TCI state configuration(s) includes a TCI state ID identifying the corresponding TCI state configuration.
  • the first TCI state configuration(s) includes TCI state configuration(s) 1, ..., L, where L is a positive integer larger than zero.
  • the TCI state configuration(s) 1 , . .. , L include TCI state ID(s) 1 , .. . , L identifying the TCI state configuration(s) 1, ... , L, respectively.
  • DU 174 includes the TCI state ID 1 in the first LTM command to instruct the UE 102 to apply the TCI state configuration 1 to communicate on the first cell.
  • the UE 102 accesses and/or communicates on the first cell using the TCI state configuration 1 in accordance with the TCI state ID 1. For example, the UE 102 monitors one or more PDCCHs and/or transmits the first transmission, using the TCI state configuration 1.
  • the DU 174 detects that the UE 102 accesses the first cell and communicates with the UE 102 on the first cell, based on the TCI state configuration 1. For example, the DU 174 receives the first transmission from the UE 102 on the first cell, based on the TCI state configuration 1.
  • the DU 174 includes the TCI state ID 2 in the first LTM command to indicate to the UE 102 to apply the TCI state configuration 2 to communicate on the first cell, in addition to the TCI state ID 1.
  • the UE 102 accesses and/or communicates 332 on the first cell using the TCI state configurations 1 and 2 in accordance with the TCI state ID 1 and the TCI state ID 2.
  • the UE 102 monitors one or more PDCCHs on the first cell using the TCI state configuration 1 and transmits the first transmission on the first cell using the TCI state configuration 2.
  • the UE 102 monitors one or more PDCCHs on the first cell using the TCI state configuration 1 and the TCI state configuration 2 and transmits the first transmission on the first cell using one of the TCI state configurations 1 and 2.
  • the DU 174 detects that the UE 102 accesses the first cell and communicates with the UE 102 on the first cell, based on the TCI state configuration 1 and/or the TCI state configuration 2. For example, the DU 174 receives the first transmission from UE 102 on the first cell, based on one of the TCI state configurations 1 and 2.
  • the DU 174 might not include a TCI state ID in the first LTM command.
  • the UE 102 communicates on the first cell with the first DU using the at least one first TCI state, after (e g., in response to) receiving the first LTM command.
  • the DU 174 detects that the UE 102 accesses the first cell and communicates with the UE 102 on the first cell, based on the first TCI state configuration(s).
  • the DU 174 before transmitting the first LTM command, might transmit one or more activation commands to the UE to activate some or all of the first TCI state configuration(s).
  • each of the activation command(s) is a MAC CE.
  • each of the activation command(s) is a DCI.
  • the DU 174 includes the TCI state ID 1 and/or TCI state ID 2 in the activation command(s) to activate the TCI state configuration 1 and/or the TCI state configuration 2, respectively. Accordingly, UE 102 determines or identifies that the TCI state configuration 1 and/or the TCI state configuration 2 is/are activated upon receiving 330 the activation command(s).
  • the DU 174 includes all the TCI state ID(s) for the first TCI state configuration(s) in the activation command(s). Accordingly, UE 102 determines or identifies that the first TCI state configuration(s) is/are activated upon receiving 330 the activation command(s). In some embodiments, the DU 174 refrains from including, in the first LTM command, a TCI state ID for a TCI state configuration that the DU 174 has not activated for the UE 102. In some embodiments, the DU 174 includes the cell ID 1 or the cell index 1 in the activation command(s).
  • the UE 102 determines that the activation command(s) activates the one or more TCI state configurations in the first TCI state configuration(s), where each of the TCI state ID(s) identifies a particular TCI state configuration of the TCI state configuration(s).
  • the UE 102 communicates with the DU 174 on the cell 124A (e.g.. events 302, 304. 318, 320. 324, 330), using one or more TCI state configurations.
  • each of the TCI state configuration(s) configures a TCI state for the UE 102 to transmit and/or receive data and/or control signal on the cell 124A (i.e., the serving cell).
  • the UE 102 stops using the TCI configuration(s) upon receiving the first LTM command.
  • the UE 102 After successfully accessing the first cell (i.e.. the switching cell), the UE 102 communicates 336 with the DU 174 on the first cell using the LTM DU configuration 1 and/or reference LTM DU configuration and communicates with the CU 172 via the DU 174. In such cases, the DU 174 communicates 336 with the UE 102 on the first cell using the LTM DU configuration 1. In some scenarios or embodiments, the UE 102 communicates 336 PUSCH transmissions. PDSCH transmissions, PUCCH transmissions, PDCCH transmissions, and/or sounding reference signal (SRS) transmissions with the DU 174 on the first cell.
  • SRS sounding reference signal
  • UE 102 uses some or all of the first TCI state configuration(s) to perform 336 the communication with the DU 174.
  • DU 174 uses some or all of the first TCI state configuration(s) to perform 336 the communication with the UE 102.
  • the DU 174 includes one or more additional TCI state configurations in the LTM DU configuration 1.
  • the DU 174 might transmit one or more activation commands to the UE 102 via the first cell in event 336 to activate the additional TCI state configuration(s).
  • UE 102 determines that the additional TCI state configuration(s) is/are activated upon receiving the activation command(s).
  • each of the activation command(s) is a MAC CE.
  • each of the activation command(s) is a DCI.
  • the UE 102 After receiving the activation command(s), the UE 102 uses the additional TCI state configuration(s) to communicate with the DU 174 on the first cell.
  • the DU 174 uses the additional TCI state configuration(s) to communicate with the UE 102 on the first cell.
  • the UE 102 communicates 336 with the DU 174 on the first cell in accordance with the LTM DU configuration 1 and at least a portion of the reference LTM DU configuration. In other words, UE 102 communicates 336 with the DU 174 in accordance with configuration parameters in the LTM DU configuration 1 and the reference LTM DU configuration. Similarly, the DU 174 communicates 336 with the UE 102 on the first cell in accordance with the LTM DU configuration 1 and at least a portion of the reference LTM DU configuration. In other words, the DU 174 communicates 336 with the UE 102 in accordance with configuration parameters in the LTM DU configuration 1 and the reference LTM DU configuration.
  • the UE 102 In the case that the UE 102 receives neither the LTM CU configuration 1 nor a/the reference LTM CU configuration, the UE 102 communicates 336 with the CU 172 via the DU 174 using the serving CU configuration. Correspondingly, if the CU 172 neither transmits the LTM CU configuration 1 nor a/the reference CU configuration to the UE 102, the CU 172 communicates 336 with the UE 102 via the DU 174 using the serving CU configuration.
  • the UE 102 communicates 336 with the CU 172 via the DU 174 using the LTM CU configuration 1 and (at least a portion ol) the reference LTM CU configuration not augmented by the LTM CU configuration 1.
  • the CU 172 communicates 336 with the UE 102 via the DU 174 using the LTM CU configuration 1 and (at least a portion of) the reference LTM CU configuration not augmented by the LTM CU configuration 1.
  • the UE 102 In the case that the UE 102 receives the LTM CU configuration 1 and does not receive the reference LTM CU configuration from the CU 172, the UE 102 communicates 336 with the CU 172 via the DU 174 using the LTM CU configuration 1. In this case, the CU 172 communicates 336 with the UE 102 via the DU 174 using the LTM CU configuration 1. If the LTM CU configuration 1 is a full configuration, the UE 102 and CU 172 communicates 336 with each other via the DU 174 using the LTM CU configuration 1 instead of the serving CU configuration.
  • the UE 102 determines that the LTM CU configuration 1 is a full configuration.
  • the CU 172 determines to configure or configures the LTM CU configuration 1 as a full configuration, the CU 172 does not transmit a/the reference LTM CU configuration to the UE 102.
  • the CU 172 includes a first indication (e.g., a field or IE) in the LTM CU configuration 1, the first container, the element 1, or the RRC reconfiguration message 316 to indicate that the LTM CU configuration 1 is a full configuration.
  • the UE 102 and CU 172 communicate 336 with each other via the DU 174 using the LTM CU configuration 1 and at least a portion of the serving CU configuration, not augmented by the LTM CU configuration 1. In some embodiments, if the UE 102 does not receive a/the reference LTM CU configuration from the first BS 104, the UE 102 determines that the LTM CU configuration 1 is a delta configuration to augment the serving CU configuration.
  • the CU 172 determines to configure or configures the LTM CU configuration 1 as a delta configuration to augment the serving CU configuration, the CU 172 does not transmit a/the reference LTM CU configuration to the UE 102.
  • the CU 172 indicates that the LTM CU configuration 1 is a delta configuration to augment the serving CU configuration, by excluding the first indication in the LTM CU configuration 1 , the first container, the element 1. and/or the RRC reconfiguration message 316.
  • the CU 172 includes a second indication (e.g., a field or IE) in the LTM CU configuration 1, the first container, the element 1, or the RRC reconfiguration message 316 to indicate that the LTM CU configuration 1 is a delta configuration to augment the serving CU configuration.
  • the CU 172 indicates that the LTM CU configuration 1 is a full configuration, by excluding the second indication in the LTM CU configuration 1, the first container, the element 1, and/or the RRC reconfiguration message 316.
  • the UE 102 In case that the UE 102 receives the reference LTM CU configuration and does not receive the LTM CU configuration 1 from the CU 172, the UE 102 communicates 336 with the CU 172 via the DU 174 using the reference LTM CU configuration. In this case, the CU 172 communicates 336 with the UE 102 via the DU 174 using the reference LTM CU configuration. If the reference LTM CU configuration is a full configuration, the UE 102 and CU 172 communicates 336 with each other via the DU 174 using the reference LTM CU configuration instead of the serving CU configuration.
  • the UE 102 and CU 172 determine that the reference LTM CU configuration 1 is a full configuration as specified in a 3GPP TS.
  • the CU 172 includes a first indication (e.g., a field or IE) in the reference LTM CU configuration, the first container or the RRC reconfiguration message 316 to indicate that the reference LTM CU configuration is a full configuration. If the reference LTM CU configuration is a delta configuration to augment the serving CU configuration, the UE 102 and CU 172 communicates 336 with each other via the DU 174 using the reference LTM CU configuration and at least a portion of the serving CU configuration, not augmented by the reference LTM CU configuration.
  • a first indication e.g., a field or IE
  • the CU 172 indicates that the reference LTM CU configuration is a delta configuration to augment the serving CU configuration, by excluding the first indication in the reference LTM CU configuration, the first container, the element 1. and/or the RRC reconfiguration message 316.
  • the CU 172 includes a second indication (e.g., a field or IE) in the reference LTM CU configuration, the first container, the element 1, or the RRC reconfiguration message 316 to indicate that the reference LTM CU configuration is a delta configuration to augment the serving CU configuration.
  • the CU 172 indicates that the reference LTM CU configuration is a full configuration, by excluding the second indication in the reference LTM CU configuration, the first container, the element 1, and/or the RRC reconfiguration message 316.
  • the UE 102 In the case that the UE 102 receives neither the reference LTM CU configuration, nor the LTM CU configuration 1 from the CU 172, the UE 102 communicates 336 with the CU 172 via the DU 174 using the serving LTM CU configuration. In this case, the CU 172 communicates 336 with the UE 102 via the DU 174 using the serving LTM CU configuration.
  • the UE 102 transmits an RRC message (e.g., RRC reconfiguration complete message) to the CU 172, via the DU 174, and to the first cell to indicate that the UE 102 applies the LTM DU configuration 1.
  • RRC message e.g., RRC reconfiguration complete message
  • the UE 102 may include the RRC message in the message 3 or message A.
  • the UE 102 transmits the RRC message after completing the random access procedure.
  • the UE 102 includes the RRC message in a PUSCH transmission of the at least one PUSCH transmission.
  • the UE 102 may transmit the RRC message to the first BS 104 via the cell 124A.
  • the DU 174 receives the RRC message, the DU 174 transmits the RRC message to the CU 172.
  • the UE 102 refrains from transmitting the RRC message to the first BS 104 in response to applying the LTM DU configuration 1 or receiving the first LTM command.
  • the UE 102 may include or transmit data in the message 3, message A or PUSCH transmission as described above.
  • the UE 102 may generate a MAC PDU and/or a RLC PDU including the data and transmits or includes the MAC PDU and/or RLC PDU in the PUSCH transmission.
  • the data may be a PDCP PDU, a SDAP PDU, an LTE Positioning Protocol (LPP) PDU, an RRC PDU and/or an NAS PDU.
  • LPP LTE Positioning Protocol
  • the RRC PDU includes an UL-DCCH-Message excluding a RRC reconfiguration complete message.
  • the NAS PDU includes a Mobility 7 Management (MM) message or a Session Management (SM) message.
  • the MM message may be a 5G MM message or a 6G MM message
  • the SM message may be a 5G SM message or a 6G SM message.
  • the DU 174 may transmit 334 a DU-to-CU message (e.g., Access Success message) to the CU 172 (e.g., a CP of the CU 172).
  • the DU 174 may include the cell ID 1 of the first cell in the DU-to-CU message of the event 334.
  • the cell ID may be a PCI or a CGI.
  • CU 172 determines that the UE 102 connects to the first cell upon receiving the DU-to-CU message of event 334.
  • the DU 174 may transmit a DL Data Delivery Status message or frame to the CU 172 (e.g., a UP of the CU 172).
  • the CU 172 when or after the CU 172 receives the DU-to-CU message 329, the CU 172 might stop or suspend transmitting DL data for the UE 102 to the DU 174 until receiving the DU-to-CU message 334. The CU 172 might do so because the DU 174 cannot buffer DL data for the UE 102 during the LTM execution in the events 330 and/or 332. After receiving the DU-to-CU message 334, the CU 172 continues or resumes transmitting DL data for the UE 102 to the DU 174.
  • the CU 172 when the CU 172 receives the DU-to-CU message 329, the CU 172 might continue transmitting DL data for the UE 102 to the DU 174. The CU 172 might do so because the DU 174 may buffer DL data for the UE 102 during the LTM execution in the events 330 and/or 332. When or after the DU 174 detects that UE 102 accesses cell 1, the DU 174 transmits the DL data to the UE 102 via cell 1.
  • the DU 174 may stop communicating with the UE 102 on the cell 124A and/or release resources of the cell 124A configured for the UE 102.
  • the DU 174 may generate some or all of the LTM DU configuration 1 and/or LTM DU configuration(s) 2, ..., N as full configuration(s) to replace the serving DU configuration. If the LTM DU configuration 1 is a full configuration, the UE 102 and DU 174 communicate 336 with each other in accordance with the LTM DU configuration 1 instead of the serving DU configuration.
  • the DU 174 includes an indication specifying that the LTM DU configuration 1 is a full configuration in the LTM DU configuration 1. In each of the LTM DU configuration(s) 2. . . . , N, the DU 174 may include an indication to announce that the corresponding DU configuration is a full configuration.
  • Each of the indication(s) in the LTM DU configuration(s) 1, ... , N may be a field or IE (i.e., the same field or IE).
  • the CU 172 may include, in the RRC reconfiguration message of the events 316, 318, a single indication specifying that the LTM DU configuration(s) 1 and/or 2, . . . , N is/are full configured on(s).
  • the CU 172 may include, in the additional RRC reconfiguration message, a single indication specifying that the LTM DU configuration(s) 2, . .. , N is/are full configured on(s).
  • the CU 172 may include, in the first container, a single indication specifying that the LTM DU configuration(s) 1 and/or 2, .. . , N is/are full configuration(s). In yet other embodiments, for each of the LTM DU configured on(s) 2, . . . , N, the CU 172 may include, in the first container, a particular indication specifying the corresponding LTM DU configuration is a full configuration. In the case of the second container, the CU 172 may include, in the second container, a single indication specifying that the LTM DU configuration(s) 2, .. . , N is/are full configuration(s).
  • the CU 172 may include, in the element 1, includes an indication specifying that the LTM DU configuration 1 is a full configuration.
  • the CU 172 may include an indication specifying that the corresponding LTM DU configuration is a full configuration.
  • the UE 102 may determine that the LTM DU configuration 1 and/or LTM DU configuration(s) 2, . .. , N is/are full configured on(s) based on the indication(s) above.
  • each of the indication(s) above is different from afullConflg field defined in the current 3GPP TS.
  • each of the indication(s) above is a fullConfig field defined in the current 3GPP TS.
  • the UE 102 in the event 336 does not apply the reference LTM DU configuration, if received from the first BS 104, e.g., in the RRC reconfiguration message 318.
  • the DU 174 might not include a/the reference LTM DU configuration in the first DU-to-CU message 310.
  • the DU 174 may generate the LTM DU configuration 1 and/or LTM DU configuration(s) 2, . . . , N as delta configuration(s) that augment (a portion of) the reference LTM DU configuration.
  • the DU 174 generates the LTM DU configuration(s) 1, ...N based on the reference LTM DU configuration. For example, if the LTM DU configuration 1 is a delta configuration, the UE 102 and DU 174 augment (the portion of) the reference LTM DU configuration with the LTM DU configuration 1.
  • the UE 102 and DU 174 communicate 336 with each other in accordance with the LTM DU configuration 1 and unaugment a portion of the reference LTM DU configuration.
  • the LTM DU configuration(s) 1, and/or 2... , N, first container, second container, or element(s) 1 , . .. , N exclude indication(s) specify ing that the LTM DU configuration(s) 1, and/or 2. . . , N is/are full configuration(s) to indicate that the LTM DU configuration(s) 1 and/or 2, .. . , N is/are delta configuration(s).
  • the UE 102 may determine that each of the LTM DU configuration(s) 1 and/or 2. . ..
  • N is a delta configuration based on the fact that the indication is excluded in the LTM DU configuration(s) 1 and/or 2, ... , N, first container, second container, or element(s) 1 and/or 2, . . . , N.
  • the UE 102 determines that the LTM DU configuration 1. and/or the LTM DU configuration(s) 2. ... . N are full configuration ⁇ ).
  • the DU 174 does not obtain a reference LTM DU configuration for the UE 102 (i.e., the DU 174 does not generate a reference LTM DU configuration for the UE 102 and/or receive a reference LTM DU configuration for the UE 102 from the CU 172), the DU 174 generates the LTM DU configuration 1, and/or the LTM DU configuration(s) 2, .... N as full configuration(s).
  • the UE 102 determines that the LTM DU configuration 1, and/or the LTM DU configuration(s) 2, . .. , N are delta configuration(s) to augment the serving DU configuration. In such cases, UE 102 communicates 336 with the DU 174 in accordance with the LTM DU configuration 1 and at least a portion of the serving DU configuration not augmented by LTM DU configuration 1.
  • the DU 174 does not obtain a reference LTM DU configuration for the UE 102 (i.e., the DU 174 does not generate a reference LTM DU configuration for the UE 102 and/or receive a reference LTM DU configuration for the UE 102 from the CU 172).
  • the DU 174 generates the LTM DU configuration 1, and/or the LTM DU configuration(s) 2, ... , N as delta configuration(s) to augment the serving DU configuration.
  • the DU 174 communicates 336 with the UE 102 in accordance with the LTM DU configuration 1 and the at least a portion of the serving DU configuration.
  • the UE 102 uses a UE MAC entity (e.g., MAC 204B) to communicate with a DU MAC entity (e.g., MAC 204B) of the DU 174 (e.g., the events 302, 304, 318. 320, 324, 330 and/or 331).
  • the UE 102 resets the UE MAC entity, after or in response to receiving the first LTM command and before performing 332 the random access procedure or communicating 336 with the DU 174 via the first cell.
  • the DU 174 resets the DU MAC entity 7 after (e.g., in response to) transmitting the first LTM command, receiving the acknowledgement 331, or determining that the UE 102 connects to the first cell.
  • the UE 102 when the UE 102 resets the UE MAC entity, the UE 102 performs at least one of the following actions for the UE MAC entity (i.e., UE MAC reset or full UE MAC reset):
  • timeAlignmentTimer(s) • consider timeAlignmentTimer(s) as expired, if the UE 102 is configured to perform the random access procedure (e.g., the event 332) in the configuration (e.g., the configuration 1);
  • the DU 174 when the DU 174 resets the DU MAC entity, the DU 174 performs at least one of the following actions for the DU MAC entity (i.e., DU MAC reset or full DU MAC reset):
  • timeAlignmentTimer(s) that the DU 174 starts and/or maintains for the UE 102, as expired, if the UE 102 is configured to perform the random access procedure (e.g., the event 332) in the configuration (e g., the configuration 1);
  • the UE 102 may determine to partially or fully reset the UE MAC entity.
  • the UE 102 when the UE 102 resets the UE MAC entity as described above, the UE 102 fully resets the UE MAC entity 7 (i.e., a full UE MAC reset). In the full UE MAC reset, UE 102 performs some or all of the actions described above.
  • the UE 102 when the UE 102 resets the UE MAC entity as described above, the UE 102 partially resets the UE MAC entity 7 (i.e., a partial UE MAC reset). In the partial UE MAC reset, UE 102 performs a subset or portion of the some or all of the actions in the full UE MAC reset.
  • the partial UE MAC reset includes at least one of the following actions: • consider timeAlignmentTimer(s) of the UE 102 as expired, if the UE 102 is configured to perform the random access procedure (e.g., the event 332) in the configuration (e.g., the configuration 1);
  • the partial UE MAC reset further includes at least one of the following actions:
  • the partial UE MAC reset further includes at least one of the following actions: stop a first portion of the one or more timers and retain the rest of the one or more timers; set new data indicator(s) (NDI(s)) for UL HARQ process(es) to value 0; set NDI(s) for HARQ process ID(s) to value 0 for monitoring PDCCH in Sidelink resource allocation mode 1;
  • the DU 174 may determine to partially or fully reset the DU MAC entity.
  • the DU 174 when the DU 174 resets the DU MAC entity as described above, the DU 174 fully resets the DU MAC entity (i. e. , a full DU MAC reset). In the full DU MAC reset, DU 174 performs some or all of the actions described above.
  • the DU 174 when the DU 174 resets the DU MAC entity as described above, the DU 174 partially resets the DU MAC entity (i.e., a partial DU MAC reset). In the partial DU MAC reset, the DU 174 performs a subset or portion of the some or all of the actions in the full DU MAC reset.
  • the partial DU MAC reset includes at least one of the following actions in the partial MAC reset:
  • timeAlignmentTimer (s that the DU 174 starts and/or maintains for the UE 102, as expired, if the UE 102 is configured to perform the random access procedure (e.g., the event 332) in the configuration (e.g., the configuration 1);
  • the partial DU MAC reset includes at least one of the following actions for the MAC entity (i.e., DU MAC reset):
  • the UE 102 refrains from resetting the UE MAC entity in response to receiving the first LTM command.
  • the DU 174 refrains from resetting the DU MAC entity after (e.g., in response to) transmitting the first LTM command, receiving the acknowledgement 331 or determining that the UE 102 connects to the first cell.
  • the UE 102 communicates with the DU 174 on the first cell using the UE MAC entity (not reset).
  • the DU 174 communicates with the UE 102 using the DU MAC entity (not reset) on the first cell during or after the random access procedure 332 or after determining that the UE 102 connects to the first cell.
  • the UE 102 uses at least one UE RLC entity (e.g., RLC 206B) to communicate RLC PDUs with at least one DU RLC entity (e.g., RLC 206B) of the DU 174 (e.g., the events 302, 304, 318, 320, 324, 330 and/or 331).
  • the UE 102 reestablishes some or all of the at least one UE RLC entity, after or in response to receiving the first LTM command and before performing 332 the random access procedure or communicating 336 with the DU 174 via the first cell.
  • the DU 174 reestablishes some or all of the at least one DU RLC entity after (e.g., in response to) transmitting the first LTM command, receiving the acknowledgement 331, or determining that the UE 102 connects to the first cell.
  • the LTM DU configuration 1 may or may not include one or more RLC reestablishment indications (e.g., reestablishRLC field(s)) configuring the UE 102 to reestablish some or all of the at least one UE RLC entity.
  • RLC reestablishment indications e.g., reestablishRLC field(s)
  • the LTM DU configuration 1 includes the RLC reestablishment indication configuring the UE 102 to reestablish a first UE RLC entity, of the at least one UE RLC entity, which the UE 102 uses to communicate RLC PDU(s) with the DU 174, the UE 102 reestablishes the first UE RLC entity in response to the RLC reestablishment indication and the first LTM command.
  • UE 102 may reestablish the first UE RLC entity before performing 332 the random access procedure or communicating 336 with the DU 174 via the first cell.
  • UE 102 may reestablish the first UE RLC entity while or after performing 332 the random access procedure. Otherwise, if the LTM DU configuration 1 does not include the RLC reestablishment indication, the UE 102 refrains from reestablishing the first UE RLC entity’ in response to the first LTM command.
  • the UE 102 when the UE 102 reestablishes the first UE RLC entity, the UE 102 performs at least one of the following actions for the first UE RLC entity’: • discard RLC SDU(s), RLC SDU segment(s), and RLC PDU(s), if any;
  • the state variables and timer(s) are defined in 3GPP TS 38.322.
  • the UE 102 refrains from reestablishing the first UE RLC entity upon or when receiving the first LTM command. In other words, the UE 102 refrains from performing the actions for reestablishing the first UE RLC entity of the UE 102 upon or when receiving the first LTM command. In some embodiments, if the LTM DU configuration 1 or element 1 does not include the RLC reestablishment indication and includes an indication specifying that the configuration 1 is a full configuration, the UE 102 may reestablish the first UE RLC entity 7 of the UE 102 upon or when receiving the first LTM command.
  • the UE 102 refrains from reestablishing the first UE RLC entity upon or when receiving the first LTM command.
  • the DU 174 reestablishes some or all of at least one DU RLC entity (e.g., NR RLC 206B) that the DU 174 uses to communicate with the at least one UE RLC entity of the UE 102 (e.g.. the events 302, 304, 318, 320, 324, 330 and/or 331) in response to the RLC reestablishment indication.
  • at least one DU RLC entity e.g., NR RLC 206B
  • the DU 174 reestablishes some or all of at least one DU RLC entity (e.g., NR RLC 206B) that the DU 174 uses to communicate with the at least one UE RLC entity of the UE 102 (e.g.. the events 302, 304, 318, 320, 324, 330 and/or 331) in response to the RLC reestablishment indication.
  • the DU 174 reestablishes a first DU RLC entity 7 of the at least one DU RLC entity after transmitting the first LTM command, receiving an acknowledgement for the first LTM command from the UE 102, or determining that the UE 102 connects to the first cell.
  • the acknowledgement is a HARQ ACK.
  • the acknowledgement is a MAC CE.
  • the acknowledgement is a PUCCH transmission.
  • the DU 174 when the first BS 104 reestablishes the first DU RLC entity, the DU 174 performs at least one of the following actions for the first DU RLC entity:
  • the state variables and timer(s) are defined in 3GPP TS 38.322.
  • UE 102 refrains from reestablishing some or all of the at least one UE RLC entity in response to receiving the first LTM command.
  • DU 174 refrains from reestablishing some or more of the at least one DU RLC entity after (e.g., in response to) transmitting the first LTM command, receiving the acknowledgement 331, or determining that the UE 102 connects to the first cell.
  • UE 102 communicates with the DU 174 on the first cell using some or all of the at least one UE RLC entity (not reestablished).
  • the some or all of the at least one UE RLC entity includes the first UE RLC entity and/or a second UE RLC entity.
  • the DU 174 communicates with the UE 102 using the some or all of the at least one DU RLC entity (not reestablished) on the first cell during or after the random access procedure 332 or after determining that the UE 102 connects to the first cell.
  • the some or all of the at least one DU RLC entity includes the first DU RLC entity and/or a second DU RLC entity .
  • UE 102 uses at least one UE PDCP entity (e.g., PDCP 210) to communicate UL PDCP PDUs and/or DL PDCP PDUs with at least one CU PDCP entity (e.g., PDCP 210) of the CU 172 in event 302.
  • the UE 102 performs a PDCP recovery procedure for some or all of the at least one UE PDCP entity, after or in response to receiving the first LTM command.
  • UE 102 performs a PDCP recovery procedure for a first UE PDCP entity of the at least one UE PDCP entity, after or in response to receiving the first LTM command.
  • UE 102 may or may not reestablish the first UE PDCP entity. After or in response to performing the PDCP recovery procedure, the UE 102 may retransmit at least a portion of the UL PDCP PDUs to the CU 172 via the DU 174 and the first cell in the event 336.
  • the CU 172 performs a PDCP recovery procedure for some or all of the at least one CU PDCP entity after or in response to transmitting the first LTM command.
  • the CU 172 performs a PDCP recovery procedure for a first CU PDCP entity of the at least one CU PDCP entity, after or in response to transmitting the first LTM command.
  • the CU 172 performs the PDCP recovery procedure for the first CU PDCP entity in response to receiving the DU-to-CU message 329 or 334. In other embodiments, the CU 172 performs the PDCP recovery procedure for the first CU PDCP entity in response to receiving the DL Data Delivery Status message. In the PDCP recovery procedure, CU 172 may or may not reestablish the first CU PDCP entity . After or in response to performing the PDCP recovery 7 procedure, the CU 172 may retransmit at least a portion of the DL PDCP PDUs to the UE 102 via the DU 174 and the first cell in event 336.
  • the UE 102 refrains from reestablishing some or all of the at least one UE PDCP entity in response to receiving the first LTM command.
  • some or all of the at least one UE PDCP entity includes the first UE PDCP entity and/or a second UE PDCP entity.
  • the CU 172 refrains from reestablishing some or more of the at least one CU PDCP entity, after (e.g., in response to) receiving the DU-to-CU message 329 or 340 or after (e.g., in response to) receiving the DL Data Delivery Status message.
  • the UE 102 communicates with the CU 172 via the DU 174 and the first cell using some or all of the at least one UE PDCP entity (not reestablished).
  • some or all of the at least one UE PDCP entity’ includes the first UE PDCP entity and/or a second UE PDCP entity.
  • the CU 172 communicates with the UE 102 using some or all of the at least one CU PDCP entity (not reestablished) via the DU 174 and the first cell.
  • some or all of the at least one CU PDCP entity includes the first CU PDCP entity and/or a second CU PDCP entity'.
  • the CU 172 may transmit 338 a CU-to-DU message (e.g., a UE Context Modification Request message) to the DU 174 to indicate the DU 174 to stop communicating with the UE 102 and/or to release or suspend resources, of the cell 124A. configured for the UE 102.
  • the DU 174 may stop communicating on the cell 124A with the UE 102 and/or release or suspend resources, of the cell 124A, configured for the UE 102, and transmit 340 a DU-to-CU message (e.g., a UE Context Modification Response message) to the CU-172.
  • the optional events 338 and 340 are collectively referred to in FIG. 3 as a “resource release procedure’" 396.
  • the UE 102 transmits 344 at least one measurement report to the DU 174.
  • the at least one measurement report includes at least one measurement result for a second cell (i.e., cell 2).
  • the at least one measurement result indicates that the second cell is suitable for communication with UE 102 and/or the first cell is not suitable for communication with the UE 102.
  • the DU 174 determines to activate the LTM DU configuration 2 and generates a second LTM command to activate the LTM DU configuration 2 (i.e., the second LTM command commands the UE 102 to apply the LTM DU configuration 2).
  • the DU 174 then transmits 350 the second LTM command to the UE on the first cell.
  • the DU 174 When or in response to determining to activate the LTM DU configuration 2 or transmit the second LTM command, the DU 174 might transmit 349 to the CU 172 a DU-to- CU message indicating LTM command (being) executed.
  • the DU 174 includes the cell ID 2 or the ID 2 (i.e., LTM ID) in the DU-to-CU message 349 to indicate that the DU 174 is to activate the LTM DU configuration 2.
  • the DU may transmit the DU-to- CU message 349 to the CU 172 before or after transmitting the LTM command 350.
  • events 324, 326, 328, 330, 331, 332, 334 and/or 336 may be applied to the events 344, 346. 348, 350, 351, 352, 354 and/or 356 with simple changes.
  • “cell I 24A”. “first LTM command”, “first cell”. “ID 1”, “LTM DU configuration 1” and/or “LTM CU configuration 1” are replaced with “first cell”, “second LTM command” and “second cell”, “ID 2”, “LTM DU configuration 2”, and/or “LTM CU configuration 2”, respectively.
  • Events 344, 346, 348, 350. 351, 352, and 354 are collectively referred to, in FIG. 3, as an “LTM execution procedure” 398.
  • the events 304, 306, 390, 392, 394, 324, 326, 328. 329, 330. 331, 332, 334. 336, 396. 398, or 356 are collectively referred to in FIG. 3 as a LTM DU configuration and/or activation procedure 380.
  • the first BS 104 includes a CU 172, a source DU (S-DU) 174A and a target DU (T-DU) 174B.
  • the S-DU 174A operates the cell 124A and optionally additional cell(s), while the T-DU 174B operates the first cell (e.g., cell 124C).
  • the scenario 400 is similar to the scenario 300. Thus, the descriptions for scenario 300 may generally apply to scenario 400. The differences between the scenarios 300 and 400 are described below.
  • UE 102 communicates 402 with the S-DU 174A on cell 124A using a serving DU configuration and communicates with the CU 172 via the S-DU 174A.
  • the S-DU 174A is a serving DU similar to the DU 174 in FIG. 3.
  • the UE 102 transmits 404, 406 at least one measurement report (e.g., LI or L3 measurement report(s)) to the CU 172 via the S-DU 174A.
  • the CU 172 determines to prepare cell(s) 1 , . . .
  • N (operated by the T-DU 174B) for LTM for the UE 102, where N is a positive integer larger than 0 or 1.
  • the cell(s) 1, ... , N are identified by cell ID(s) 1 , , N, respectively.
  • the CU 172 performs 490 an LTM preparation procedure with the T-DU 174B to (request the T-DU 174B to) prepare cell(s) 1 , . .. , N for LTM for the UE 102.
  • N may be a positive integer larger than zero or 1.
  • the CU 172 transmits a CU-to-DU message, including the cell ID(s) 1, . . .
  • the T-DU 174B transmits a DU-to-CU message including the LTM DU configuration(s) 1, . . . , N to the CU 172, similar to the event 310.
  • the LTM DU configuration(s) 1, ... , N configures the cell(s) 1, ... . N for LTM. respectively.
  • the LTM DU configuration(s) 1, . . . , N include configuration parameters for communication on the cell(s) 1, ... , N, respectively.
  • the CU-to-DU message and DU-to-CU message in procedure 490 are UE Context Setup Request message and UE Context Setup Response message, respectively.
  • the CU 172 then transmits the LTM DU configuration(s) 1. .... N in an RRC reconfiguration message in an LTM configuration delivery procedure 494, similar to the LTM configuration delivery procedure 394.
  • the T-DU 174B may include cell index(es) 1, .... N in the LTM DU configuration(s) 1, ... , N, respectively.
  • the CU 172 may set the cell index(es) 1. .... N to different values and include the cell index(es) 1 , .. . , N in the CU-to-DU message of the procedure 490.
  • the CU 172 After performing the LTM preparation procedure 490, the CU 172 might perform an additional LTM preparation procedure(s) with the T-DU 174B to prepare cell(s) N+l, ... , N+M for LTM for the UE 102, similar to the procedure 490, where M is a positive integer larger than zero. The CU 172 might determine to do so based on one or more measurement reports received from the UE 102 via the S-DU 174A, similar to the events 404, 406. In the additional LTM preparation procedure, the CU 172 transmits a CU-to-DU message including cell ID(s) N+l, . . .
  • the T-DU 174B transmits a DU-to-CU message including the LTM DU configuration(s) N+l, ... , N+M to the CU 172.
  • the LTM DU configuration(s) N+l, ... , N+M configures the cell(s) N+l, ...
  • the LTM DU configuration(s) N+l, . . . , N+M include configuration parameters for communication on the cell(s) N+l, ... , N+M, respectively.
  • the CU 172 then transmits the LTM DU configuration(s) N+l, . . . , N+M in an RRC reconfiguration message in an additional LTM configuration deliver ⁇ ’ procedure, similar to the LTM configuration deliver ⁇ ’ procedure 394 or 494.
  • the LTM preparation procedure 490 is a UE Context Setup procedure
  • the additional LTM preparation procedure is a UE Context Modification procedure.
  • the CU 172 and S-DU 174A might perform procedure 380 with the UE 102. as described for FIG. 3.
  • the CU 172 and S-DU 174A perform the procedure(s) 390 and/or 392 to prepare cell(s) of the S-DU 174A for LTM for the UE 102.
  • the value N in the procedure 380 or described for FIG. 3 may be the same as or different from the value N described for FIG. 4.
  • the CU 172 might receive the first DU-to-CU message including the reference LTM DU configuration from the S-DU 174A in event 310.
  • the CU 172 and S-DU 174A do not perform procedure 380 with the UE 102.
  • the CU 172 may perform 488 a reference LTM DU configuration query procedure with the S-DU 174A to obtain a reference LTM DU configuration.
  • the CU 172 transmits 460 a CU-to-DU message to the S-DU 174A to request or query a reference LTM DU configuration.
  • the CU 172 may include an indication in the CU-to-DU message to request or query a reference LTM DU configuration.
  • the S-DU 174A transmits 462 a DU-to-CU message including a reference LTM DU configuration to the CU 172.
  • the indication is a reference LTM DU configuration query indication.
  • the indication is an LTM indication, and the CU 172 might include a query indication (e.g., GNB-DU Configuration Query IE) in the CU-to-DU message.
  • the CU 172 After receiving the reference LTM DU configuration (i.e., either in the procedure 390 or in the procedure 488), the CU 172 includes the reference LTM DU configuration (received from the S-DU 174A) in the CU-to-DU message in the LTM preparation procedure 490.
  • the T-DU 174B generates the LTM DU configuration(s) 1 , . . . , N based on the reference LTM DU configuration received from the CU 172. In such cases, the T-DU 174B does not include a reference LTM DU configuration in the DU-to-CU message in procedure 490.
  • the T-DU 174B does not include a reference LTM DU configuration in the DU-to-CU message in the additional LTM preparation procedure.
  • the CU 172 might not include the reference LTM DU configuration in the CU-to-DU message in the additional LTM preparation procedure with the T-DU 174B.
  • the T-DU 174B generates the LTM DU configuration(s) N+l , . . . , N+M based on the reference LTM DU configuration received from the CU 172.
  • the CU 172 does not provide a reference LTM DU configuration to the T-DU 174B in the LTM preparation procedure 490.
  • the T- DU 174B generates a reference LTM DU configuration and generates the LTM DU configuration(s) 1. ... . N based on the reference LTM DU configuration.
  • the T- DU 174B includes the reference LTM DU configuration in the DU-to-CU message in procedure 490.
  • the CU 172 transmits the reference LTM DU configuration in the RRC reconfiguration message in procedure 490.
  • the T-DU 174B generates the LTM DU configuration(s) N+L ....
  • the T-DU 174B might not include the reference LTM DU configuration in the DU-to-CU message in the additional LTM preparation procedure.
  • the reference LTM DU configuration generated by the T-DU 174B is different from the reference LTM DU configuration generated by the S-DU 174A.
  • the reference LTM DU configuration generated by the T-DU 174B is the same as the reference LTM DU configuration generated by the S-DU 174A.
  • the CU 172 includes the LTM DU configuration(s) 1, . .. , N of the procedure 380 in the CU-to-DU message of the procedure 490, and the T-DU 174B generates the LTM DU configuration(s) 1, ... . N and/or N+l, ... , N+M, considering or based on configuration(s) in the LTM DU configuration(s) of the procedure 380.
  • an LTM DU configuration X of procedure 380 includes at least one reference signal (RS) resource configuration X, where 1 ⁇ X ⁇ N.
  • RS resource configuration(s) X configures one or more RSs or one or more RS resources associated with a cell X of the S-DU 174A.
  • the RS(s) includes SSB(s) and/or CSI-RS(s).
  • the RS resource(s) includes SSB resource(s) and/or CSI-RS resource(s).
  • each of the RS resource configuration(s) X includes an RS resource configuration ID.
  • the RS resource configuration(s) X is/are (similar to) CSI-ResourceConfig IE(s).
  • the LTM DU configuration X includes a CSI-MeasConfig IE and the CSI-MeasConfig IE includes the CSI-ResourceConfig IE(s).
  • the T-DU 174B generates at least one report configuration 1 for reporting, on cell 1 of the T- DU 174B, measurement results of the RS(s) or RS resource(s) and includes the report configuration(s) 1 in the LTM DU configuration 1 .
  • the report configuration(s) 1 is/are (similar to) CSI-ReportConfig IE(s).
  • the T- DU 174B generates at least one RS resource configuration 1, considering or based on the RS resource configuration(s) X and includes the RS resource configuration(s) 1 in the LTM DU configuration 1. In some embodiments, the T-DU 174B includes the RS resource configuration(s) X in the RS resource configuration(s) 1. In other embodiments, the T-DU 174B includes each of the RS resource configuration(s) X in the RS resource configuration(s) 1, except the RS resource configuration ID(s) in the RS resource configuration(s) X. The T- DU 174B assigns an RS resource configuration ID to a value for each of the RS resource configuration(s) 1 (including the RS resource configuration(s) X) and includes the RS resource configuration ID in the corresponding RS resource configuration.
  • the report configuration(s) 1 configures one or more UL resources (e.g., PUCCH resources or PUSCH resources) on cell 1 for the UE 102 to transmit measurement results.
  • each of the report configuration(s) 1 includes one or more RS resource configuration IDs identifying one or more RS resource configurations included in the RS resource configuration(s) 1.
  • the UE 102 After the UE 102 performs a LTM serving cell change/switch to the cell 1 from the cell 124A, the UE 102 communicates with the S-DU 174B (i.e., the T-DU 17B becomes a S-DU for the UE 102) and transmits measurement results on the UL resource(s) via the cell 1 to the S-DU 174B, in accordance with the report configuration(s) 1.
  • the S-DU 174B receives the measurement results on the UL resource (s) via cell 1 from the UE 102, in accordance with the report configuration(s) 1.
  • each of the measurement results includes one or more RS resource indicators and/or one or more quantized measurement values.
  • the UE 102 performs measurements on the RS(s) or the RS resource(s) in accordance with the RS resource configuration(s) 1 and/or the report configuration(s) 1 and obtains the quantized measurement values from the measurements.
  • the RS resource indicator(s) indicates the RS(s) or a RS resource(s) where the UE 102 perform measurements or obtains the quantized measurement values.
  • the RS resource indicator(s) includes one or more SSB resource indicators (SSBRI(s)) and/or one or more CSLRS resource indicators (CRI(s)).
  • the quantized measurement values might include one or more Ll-RSRP values and/or one or more Ll-SINR values.
  • the T-DU 174B also includes additional RS resource configuration(s) in the LTM DU configuration 1.
  • Each of the additional RS resource configuration(s) configures one or more additional RSs or one or more additional RS resources associated with cell 1.
  • the additional RS(s) includes SSB(s) and/or CSI-RS(s).
  • the additional RS resource(s) includes SSB resource(s) and/or CSI-RS resource(s).
  • each of the additional RS resource configuration(s) includes an RS resource configuration ID.
  • the additional RS resource configuration(s) is/are (similar to) CSI-ResourceConfig IE(s).
  • the T-DU 174B includes the CSI-ResourceConfig IE(s) in the CSI-MeasConfig IE.
  • the T-DU 174B generates at least one additional report configuration for reporting, on cell 1 of the T-DU 174B, measurement results of the RS(s) or RS resource(s) and includes the additional report configuration(s) in the LTM DU configuration 1.
  • the additional report configuration(s) is/are (similar to) CSI-ReportConfig IE(s).
  • the additional report configuration(s) configures one or more UE resources (e.g., PUCCH resources or PUSCH resources) on cell 1 for the UE 102 to transmit measurement results.
  • each of the additional report configuration(s) includes one or more RS resource configuration IDs identifying one or more RS resource configurations included in the additional RS resource configuration(s).
  • the S-DU 174B receives the measurement results on the UL resource (s) via cell 1, from the UE 102, in accordance with the additional report configuration(s).
  • each of the measurement results includes one or more RS resource indicators and/or one or more quantized measurement values.
  • the UE 102 performs measurements on the additional RS(s) or the additional RS resource(s) in accordance with the additional RS resource configuration(s) and/or the additional report configuration(s) and obtains the quantized measurement values from the measurements.
  • the RS resource indicator(s) indicates the additional RS(s) or a RS resource(s) where the UE 102 perform measurements or obtains the quantized measurement values.
  • the RS resource indicator(s) includes one or more SSB resource indicators (SSBRI(s)) and/or one or more CSI-RS resource indicators (CRI(s)).
  • the quantized measurement values might include one or more Ll-RSRP values and/or one or more Ll-SINR values.
  • the T-DU 174B may generate RS resource configured on(s) 2, ... , N, and/or N+l, . . . , N+M and/or report configuration(s) 2, . . . , N, and/or N+l, . . .
  • N+M considering or based on the RS resource configuration(s) X, and include the RS resource configuration(s) 2, . .. , N, and/or N+l. . .. , N+M and/or the report configuration(s) 2, . .. , N, and/or N+l, ... , N+M in the LTM DU configuration(s) 2, ... , N, and/or N+l, ... , N+M, respectively, as described above.
  • the LTM DU configuration X of the procedure 380 includes at least one TCI state configuration X, where 1 ⁇ X ⁇ N.
  • Each of the TCI state configuration(s) X configures a TCI state that associates one or two DL RSs with a corresponding QCL type.
  • the DL RS(s) may be associated with the cell X operated by the S-DU 174A.
  • each of the TCI state configuration(s) X includes a TCI state ID.
  • each of the TCI state configuration(s) X is a TCI-State IE.
  • the TCI state configuration(s) X includes/is/are an ul-TCI-ToAddModList-r 17 field, one or more TCI-UL-State-r 17 IES. a dl- OrJointTCI-StateToAddModList-rl7 field, one or more TCI-State IEs, TCI-ActivatedConfig IE, and/or a tci-StatesToAddModList field.
  • the LTM DU configuration X includes a PDSCH-Config IE and the PDSCH-Conflg IE includes the TCI state configuration(s) X.
  • the T-DU 174B generates at least one TCI state configuration 1, considering or based on the TCI state configuration(s) X, and includes the TCI state configuration(s) 1 in the LTM DU configuration 1.
  • the TCI state configuration(s) 1 includes the TCI state configuration(s) X.
  • the T-DU 174B includes each of the TCI state configuration(s) X in the TCI state configuration(s) 1, except the TCI state ID(s) in the TCI state configuration(s) X.
  • the T-DU 174B assigns a TCI state ID to a value for each of the TCI state configuration(s) 1 (including the TCI state configuration(s) X) and includes the TCI state ID in the corresponding TCI state configuration. While the UE 102 and the S-DU 174B communicate 436 with one another, the S-DU 174B might transmit a LTM command to the UE 102 to command the UE 102 to perform a fast serving cell change to the cell X.
  • the S-DU 174B includes a TCI state ID in the LTM command to indicate to the UE 102 to apply a TCI state configuration identified by the TCI state ID to communicate on the cell X, where the TCI state configuration is one of the TCI state configuration(s) X or includes configurations of one of the TCI state configuration(s) X.
  • the T-DU 174B may generate TCI state configuration(s) 2, , N, considering or based on the RS resource configuration(s) X, and include the TCI state configuration(s) 2, . .. , N, and/or N+l, . .. , N+M in the LTM DU configuration(s) 2, .. .
  • the at least one TCI configuration may be generated by one of the CU 172, S-DU 174A, or T-DU 174B.
  • the CU 172 in cases where the CU 172 performs the procedure 380 after performing the procedure 490, the CU 172 includes the LTM DU configuration(s) 1, ... , N of the procedure 490 in the CU-to-DU message of the procedure 380, and the S-DU 174A generates the LTM DU configuration(s) 1, ... . N of the procedure 380, considering or based on configurations in the LTM DU configuration(s) of the procedure 490, in a similar way as described above.
  • the CU 172 assigns ID(s) 1, , N identifying the LTM DU configuration(s) 1, ... , N (received from the T-DU 174B), respectively, and performs the procedure 492 with the T-DU 174B to provide the ID(s) 1, . . . , N and/or cell ID(s) 1, . .. , N to the T-DU 174B, similar to the procedure 392.
  • the T-DU 174B associates the ID(s) 1 , .. . , N with the LTM DU configuration(s) 1. . . . . N and/or the cell ID(s) 1, .. . , N, respectively.
  • the T-DU 174B assigns ID(s) 1 , . . . , N identifying the LTM DU configuration(s) 1, ... , N (generated by the T-DU 174B), respectively and includes the ID(s) 1. . . . , N in the DU-to-CU message of the procedure 490, similar to the event 310.
  • the CU 172 assigns ID(s) N+l, ... , N+M identifying the LTM DU configuration(s) N+l, . . . , N+M, respectively, and performs a procedure (similar to the procedure 492) with the T-DU 174B to provide the ID(s) N+l, . . .
  • the T-DU 174B associates the ID(s) N+l, ... , N+M with the LTM DU configuration(s) N+l, ... , N+M and/or the cell ID(s) N+L .... N+M, respectively.
  • the T-DU 174B assigns ID(s) N+ 1 , . .. , N+M identifying the LTM DU configuration(s) N+l , . . . , N+M, respectively and includes the ID(s) 1, ... , N in the DU-to-CU message of the additional LTM preparation procedure, similar to the event 310.
  • the CU 172 transmits 412 a CU-to-DU message including the ID(s) 1, .... N to the S-DU 174A and in response, receives 414 a DU-to-CU message from the S-DU 174A.
  • the CU-to-DU message 412 and DU-to-CU message 414 are collectively referred to in FIG. 4 as an LTM ID transfer procedure 493 or an LTM cell index transfer procedure 493.
  • messages 412 and 414 may be UE Context Modification Request message and UE Context Modification Response message, respectively.
  • the CU 172 includes the LTM DU configuration(s) 1, ... , N and/or cell ID(s) 1, ...
  • an LTM DU configuration Y of procedure 490 includes at least one RS resource configuration Y, where 1 ⁇ Y ⁇ N.
  • Each of the RS resource configuration(s) Y configures one or more RSs or one or more RS resources associated with the cell Y of the T-DU 174B.
  • the RS(s) includes SSB(s) and/or CSI-RS(s).
  • the RS resource(s) includes SSB resource(s) and/or CSI-RS resource(s).
  • each of the RS resource configuration(s) Y includes an RS resource configuration ID.
  • the RS resource configuration(s) Y is/are (similar to) CSI-ResourceConfig IE(s).
  • the LTM DU configuration Y includes a CSI-MeasConflg IE and the CSI-MeasConfig IE includes the CSI-ResourceConfig lE(s).
  • the S-DU 174A generates at least one serving report configuration for reporting, on the cell 124 A, measurement results of the RS(s) or RS resource(s) and includes the serving report configuration(s) in the first serving DU configuration.
  • the serving report configuration(s) is/are (similar to) CSI-ReportConfig IE(s).
  • the S-DU 174A generates at least one serving RS resource configuration, considering or based on the RS resource configuration(s) Y, and includes the serving RS resource configuration(s) in the first serving DU configuration.
  • the S-DU 174A includes the RS resource configuration(s) Y in the serving RS resource configuration(s).
  • the serving report configuration(s) configures one or more UL resources (e.g., PUCCH resources or PUSCH resources) on cell 124A for the UE 102 to transmit measurement results.
  • each of the serving report configuration(s) includes one or more RS resource configuration IDs identifying one or more RS resource configurations included in the serving RS resource configuration(s). While the UE 102 communicates with the S-DU 174 A, the UE 102 transmits measurement results on the UL resource(s) via the cell 124A to the S-DU 174A, in accordance with the serving report configuration(s) (e g., event 424).
  • the S-DU 174A receives the measurement results on the UL resource (s) via the cell 124A from the UE 102, in accordance with the serving report configuration(s).
  • each of the measurement results includes one or more RS resource indicators and/or one or more quantized measurement values.
  • UE 102 performs measurements on the RS(s) or the RS resource(s) in accordance with the serving RS resource configuration(s) and/or the serving report configuration(s) and obtains the quantized measurement values from the measurements.
  • the RS resource indicator(s) indicates the RS(s) or a RS resource(s) where the UE 102 performs measurements or obtains the quantized measurement values.
  • the RS resource indicator(s) includes one or more SSB resource indicators (SSBRI(s)) and/or one or more CSI-RS resource indicators (CRI(s)).
  • the quantized measurement values might include one or more Ll-RSRP values and/or one or more Ll- SINR values.
  • the LTM DU configuration Y of the procedure 490 includes at least one TCI state configuration Y, where 1 ⁇ Y ⁇ N.
  • the at least one TCI state configuration may be generated by one of the CU 172, S-DU 174A, or T-DU 174B.
  • Each of the TCI state configuration(s) Y configures a TCI state that associates one or two DL RSs with a corresponding QCL type.
  • the DL RS(s) may be associated with the cell Y operated by the T-DU 174B.
  • each of the TCI state configuration(s) Y includes a TCI state ID.
  • each of the TCI state configuration(s) Y is a TCI-State IE.
  • the TCI state configuration(s) Y includes/is/are an ul-TCI-ToAddModLlst-r 17 field, one or more TCI-UL-State-r 17 IES. a dl- OrJointTCI-StateToAddModList-rl7 field, one or more TCI-State IEs, TCI-ActivatedConflg IE and/or a tci-StatesToAddModList field.
  • the LTM DU configuration Y includes a PDSCH-Config IE and the PDSCH-Config IE includes the TCI state configured on(s) Y.
  • the S-DU 174A generates at least one serving TCI state configuration, considering or based on the TCI state configuration(s) Y and includes the serving TCI state configuration(s) in the first serving DU configuration.
  • the serving TCI state configuration(s) 1 includes the TCI state configuration(s) Y.
  • the S-DU 174A includes each of the TCI state configuration(s) Y in the serving TCI state configuration(s), except the TCI state ID(s) in the TCI state configuration(s) Y.
  • the S-DU 174A assigns a TCI state ID to a value for each of the serving TCI state configuration(s) (including the TCI state configured on(s) Y) and includes the TCI state ID in the corresponding serving TCI state configuration. While the S-DU 174A communicates 436 with the UE 102. the S-DU 174A might transmit an LTM command to the UE 102 to request the UE 102 to perform a fast serving cell change to the cell Y.
  • the S-DU 174 A includes a TCI state ID in the LTM command to request the UE 102 to apply a TCI state configuration identified by the TCI state ID, to communicate on the cell Y.
  • the TCI state configuration is one of the TCI state configuration(s) Y or includes configurations of one of the TCI state configuration(s) Y.
  • the CU 172 transmits a CU-to-DU message including the ID(s) N+l. .... N+M to the S-DU 174A and receives a DU-to-CU message from the S-DU 174A in response, similar to the CU-to-DU message 412 and the DU-to-CU message 414, respectively.
  • the CU 172 includes the LTM DU configuration(s) N+l, ... , N+M and/or cell ID(s) N+l, ... , N+M in the CU-to-DU message.
  • the CU 172 may perform multiple LTM ID transfer procedures to transmit the ID(s) N+l, ...
  • the CU 172 includes a particular portion of the ID(s) N+ 1 , .. . , N+M, cell ID(s) N+ 1 , . .. , N+M and/or LTM DU configuration(s) 1 , . .. , N in a CU-to-DU message similar to the message 412.
  • the S-DU 174 A associates the ID(s) N+l, ... , N+M with the LTM DU configuration(s) N+l, ...
  • the S-DU 174A generates a second serving DU configuration, based on the LTM DU configuration(s) N+l, N+2, ... , and/or N+M, and includes the second serving DU configuration in the DU-to-CU message.
  • the second serving DU configuration includes configurations updating (e.g., augmenting, modifying, or replacing) the first serving DU configuration and/or updating configurations included in the serving DU configuration 402 and not updated by the first serving DU configuration.
  • the second serving DU configuration includes configurations that are not included in the first serving DU configuration.
  • the S-DU 174 A generates one or more new TCI state configuration, based on TCI state configuration(s) in the LTM DU configuration(s) N+l, N+2, ... , and/or N+M, and includes the new TCI state configuration(s) in the second serving DU configuration.
  • value(s) of the ID(s) 1. .... N of the procedure 380 are different from value(s) of the ID(s) 1, . . . ., N, and the ID(s) N+l , . .. ., N+M described for the scenario 400.
  • value(s) of the cell ID(s) 1. . . . , N of the procedure 380 are different from value(s) of the cell ID(s) 1, > .. ..
  • value(s) of the cell index(es) 1, . . . , N of the procedure 380 are different from value(s) of the cell index(es) 1, . . . ., N, and the cell index(es) N+l >... .. N+M described for the scenario 400.
  • the second measurement result(s) may be or include RSRP, RSRQ, and/or SINR that the UE 102 obtains from measuring reference signal(s) transmitted on the cell 124 A.
  • the event ID, RSRP, RSRQ, and/or SINR are Ll-event ID, Ll-RSRP, Ll-RSRQ, and/or Ll-SINR, respectively.
  • the S-DU 174A might transmit 430 a first LTM command (i.e., LTM command 1) including the ID 1 to the UE 102, to request the UE 102 to perform a serving cell change/switch to the cell 1 of the T-DU 174B.
  • the first LTM command includes the ID 1. In other embodiments, the first LTM command includes the cell index 1.
  • the first LTM command may also include the at least one TCI state configuration.
  • the UE 102 receives the first LTM command, the UE 102 performs a serving cell change to cell 1, from a serving cell, in accordance with the LTM DU configuration 1.
  • the UE 102 might or might not perform 432 a random access procedure with the T-DU 174B, similar to the event 332.
  • the UE 102 may communicate 436 with the T-DU 174B on the first cell using the LTM DU configuration 1 and/or reference LTM DU configuration and communicates with the CU 172 via the T-DU 174B, similar to the event 336. If a serving cell change occurs in procedure 380, the serving cell may be cell 1 (e.g., cell 124C) or cell 2 of the S-DU 174A. Otherwise, if no serving cell change occurs in procedure 380 or the procedure 380 is not performed, the serving cell is the cell 124A.
  • the serving cell may be cell 1 (e.g., cell 124C) or cell 2 of the S-DU 174A. Otherwise, if no serving cell change occurs in procedure 380 or the procedure 380 is not performed, the serving cell is the cell 124A.
  • the UE 102 identifies the LTM DU configuration 1 and/or cell ID 1 (i.e., the cell 1), based on the ID 1, as described relative to FIG. 3. If the first LTM command includes the cell index 1, the UE 102 identifies the LTM DU configuration 1, cell ID 1 (i.e., the cell 1), and/or LTM ID 1, based the cell index 1, as described for FIG. 3. The UE 102 applies the LTM DU configuration 1 (and the at least one TCI state configuration) to communicate with the T-DU 174B, after (e.g., in response to) receiving the first LTM command or successfully accessing cell 1.
  • the S-DU 174A When or in response to determining to activate the LTM DU configuration 1 or transmit the first LTM command 430, the S-DU 174A might transmit 429 to the CU 172 a DU-to-CU message indicating LTM (being) executed.
  • the S-DU 174A includes the cell ID 1 or the ID 1 (i.e., LTM ID) in the DU-to-CU message 429 to indicate that the S-DU 174A is to activate the LTM DU configuration 1 or trigger a LTM serving cell change.
  • the S-DU 174A may transmit the DU-to-CU message 429 to the CU 172 before or after transmitting the LTM command 430.
  • the CU 172 when or after the CU 172 receives the DU-to-CU message 429, the CU 172 might stop or suspend transmitting DL data for the UE 102 to the S-DU 174A until receiving the DU-to-CU message 434. After receiving the DU-to-CU message 434, the CU 172 starts, continues or resumes transmitting DL data for the UE 102 to the T-DU 174B. When or after the T-DU 174B detects that UE 102 accesses cell 1, the T-DU 174B transmits the DL data to the UE 102 via cell 1.
  • the resource release procedure 496 may be similar to the procedure 396.
  • the CU 172 may transmit a CU-to-DU message (e.g., a UE Context Release Command message) to the S-DU 174A to release a UE context of the UE 102.
  • the S-DU 174A releases a UE context of the UE 102 and transmits 440 a DU-to-CU message (e.g., a UE Context Release Complete message) to the CU-172.
  • a CU-to-DU message e.g., a UE Context Release Command message
  • a scenario 500A the second BS 106 operates as an MN, and the first BS 104 operates as an SN.
  • the SN 104 includes a CU 172 and a DU 174.
  • the scenario 500A is similar to the scenario 300, except that the scenario 500A is a DC scenario and the scenario 300 is a single connectivity (SC) scenario.
  • the MN 106 may include a CU and a DU similar to the first BS 104 of FIG. 3.
  • UE 102 is in DC communication with MN 106 and with SN 104.
  • the UE 102 communicates with the DU 174 on cell 124A using a serving DU configuration and communicates with the CU 172 via the DU 174 using a serving CU configuration, similar to event 302.
  • UE 102 does not communicate with the CU 172 via the DU 174 in the event 302.
  • the UE 102 in DC may communicate 502 UL PDUs and/or DL PDUs with the MN 106 and/or SN 104 via radio bearers which may include SRBs and/or DRB(s).
  • the MN 106 and/or the SN 104 may configure the radio bearers to the UE 102.
  • the UE 102 in DC communicates 502 UL PDUs and/or DL PDUs with the SN 104 on an SCG (i.e., SCG radio resources) that the SN 104 configures for communication with the UE 102.
  • the UE 102 in DC communicates UL PDUs and/or DL PDUs with the MN 106 on an MCG (i.e., MCG radio resources) in accordance with a MN configuration (i.e., MCG configuration).
  • the serving DU configuration is an SN configuration (i.e., SCG configuration).
  • the MN 106 configures the MCG which includes at least one serving cell (e.g., the cell 126 and/or other cell(s)) operated by the MN 106.
  • the SN 106A configures the SCG which includes at least one serving cell (e.g.. the cell 124A and/or other cell(s)) operated by the SN 104.
  • the MN configuration includes multiple configuration parameters, and the UE 102 receives the configuration parameters in one or more RRC messages from the MN 106.
  • the serving DU configuration includes multiple configuration parameters.
  • the UE 102 receives these configuration parameters in one or more RRC messages from the SN 104, e.g., via the MN 106 and/or on an SRB (e.g., SRB3) that the MN 106 or SN 104 configures to exchange RRC messages between the UE 102 and the SN 104.
  • SRB e.g., SRB3
  • the MN 106 may perform 580 a LTM DU configuration and/or activation procedure with the UE 102, similar to the procedures 380 and/or 480.
  • the UE 102 may transmit at least one measurement report to the CU 172 via the DU 174 and cell 124A in the events 504 and 506, similar to the events 304 and 306, respectively.
  • the UE 102 may transmit 505 at least one measurement report to the MN 106 via the cell 126.
  • MN 106 in turn transmits 507 the at least one measurement report to the CU 172.
  • the MN 106 generates at least one SN message including the at least one measurement report and transmits the at least one SN message to the CU 172 in the event 507.
  • the at least one SN message include RRC Transfer message(s) and/or SN Modification Request message(s).
  • the SN 104 determines to prepare the first cell for the UE 102, as described relative to FIG. 3.
  • the events 590, 592, 594, 524, 526, 528, 529, 530, 531, 532, 534, 536, 596, 598, or 556 are similar to the events 390, 392, 394, 324, 326, 328, 329, 330, 331, 332, 334, 336, 396, 398, or 356, respectively.
  • the UE 102 After receiving the first LTM command 530 (which may include an LTM DU configuration and/or a TCI state configuration), transmitting 531 the acknowledgement, and/or determining 532 that the UE 102 successfully connects to the first cell the UE 102 operating in DC with the MN 106 and SN 104 communicates 536 with the DU 174 on the first cell in accordance with the LTM DU configuration 1 and communicates 536 with the CU 172 via the DU 174, similar to the event 336. Later in time, the DU 174 and/or CU 172 may perform the LTM execution procedure 598 with the UE 102 to request the UE 102 to perform a cell change from the first cell to the second cell, similar to the procedure 398 or 498.
  • the first LTM command 530 which may include an LTM DU configuration and/or a TCI state configuration
  • the UE 102 operating in DC with the MN 106 and SN 104 communicates 556 with the DU 174 on the second cell in accordance with the LTM DU configuration 2 and communicates 556 with the CU 172 via the DU 174. similar to the event 356.
  • a scenario 500B is generally similar to the scenario 500 A, except that the SN 104 transmits 517. 519 the RRC reconfiguration message to the UE 102 via the MN 106 and receives 521, 523 the RRC reconfiguration complete message from the UE 102 via the MN 106.
  • the RRC reconfiguration message transmitted at 517. 519 is similar to the RRC reconfiguration message transmitted at 316, 318.
  • the RRC reconfiguration complete message received at 521, 523 is similar to the RRC reconfiguration message received at 320, 322.
  • the SN 104 generates a first SN message (e.g., SN Modification Required message, SN Modification Required message, or RRC Transfer message) including the RRC reconfiguration message and transmits the first SN message to the MN 106 in the event 517.
  • the MN 106 generates a MN RRC message including the RRC reconfiguration message and transmits 519 the MN RRC message to the UE 102.
  • UE 102 generates a MN RRC response message including the RRC reconfiguration complete message and transmits 521 the MN RRC response message to MN 106.
  • the MN 106 generates a second SN message (e.g., SN Reconfiguration Complete message or RRC Transfer message) including the RRC reconfiguration complete message and transmits the second SN message to the SN 104 in event 523.
  • a second SN message e.g., SN Reconfiguration Complete message or RRC Transfer message
  • the MN RRC message and MN RRC response message may be a RRC reconfiguration message and a RRC reconfiguration complete message, respectively.
  • the events 504, 506, 505, 507, 590, 592, 594, 517, 519, 521, 523, 524, 526, 528, 529, 530, 531, 532, 534, 536, 596, 598, or 556 are collectively referred to in FIG. 5B as an “LTM DU configuration and/or activation procedure’' 582.
  • the second BS 106 operates as an MN
  • the first BS 104 operates as an SN, similar to the scenarios 300-500B.
  • the SN 104 includes a CU 172. an S-DU 174A, and a T-DU 174B, similar to the first BS 104 in the scenario 400.
  • the MN 106 may perform 680 an LTM DU configuration and/or activation procedure with the UE 102, similar to the procedures 380 and/or 480.
  • a scenario 600B is similar to the scenarios 300-500B and 600 A, except that that the SN 104 transmits 617, 619 the RRC reconfiguration message to the UE 102 via the MN 106 and receives 621, 623 the RRC reconfiguration complete message from the UE 102 via the MN 106.
  • the first BS 104 operates as an MN and an SN. similar to the scenarios 300-600B.
  • the first BS 104 includes a CU 172. a master DU (M-DU) 174 A, and a secondary DU (S-DU) 174B.
  • the CU 172 operates with the M-DU 174A as a MN, similar to the first BS 104 in FIG. 3 or the MN 106 in FIGs. 5A-6B, and the CU 172 operates with the S-DU 174B as a SN, similar to the SN 104 in FIGs. 5A-6B.
  • the UE 102 initially communicates 702 in DC with the M-DU 174A and S-DU 174B and communicates 702 with the CU 172 via the M-DU 174A and S- DU 174B.
  • the UE 102 communicates with the S-DU 174B on cell 124A using a serving DU configuration and communicates with the CU 172 via the S-DU 174B using a serving CU configuration, similar to event 302.
  • Events 704 and 706 are similar to events 304 and 306.
  • UE 102 may transmit 705 at least one measurement report to the M-DU 174A. similar to event 304.
  • the M-DU 174A in turn transmits 707 at least one DU-to-CU message including the at least one measurement report to the CU 172, similar to the event 306. While the UE 102 communicates in DC with the M-DU 174A and S-DU 174B, the CU 172 may perform 780 an LTM DU configuration and/or activation procedure with the UE 102 via the M-DU 174A, similar to the procedure 380.
  • the events 704, 706. 705, 707, 790, 792, 794, 724, 726, 728, 729, 730, 731, 732. 734, 736. 796, 798, or 756 are collectively referred to in FIG. 7A as an “LTM configuration and/or activation procedure” 781.
  • a scenario 700B is similar to the scenarios 300-600B and 700 A, except that the CU 172 transmits 717, 719 the RRC reconfiguration message to the UE 102 via the M-DU 174A and receives 721, 723 the RRC reconfiguration complete message from the UE 102 via the M-DU 174A.
  • the events 704, 706, 705, 707, 790, 792, 794, 717, 719, 721, 723, 724, 726, 728, 729, 730. 731, 732, 734, 736, 796, 798, or 756 are collectively referred to in FIG. 7B as an “LTM DU configuration and/or activation procedure” 782.
  • the first BS 104 operates as an MN and an SN, similar to the scenarios 300-700B.
  • the first BS 104 includes a CU 172, a master DU (M-DU) 174A, a secondary DU (S-DU) 174B, and a target secondary DU (T-DU) 174C.
  • the CU 172 operates with the M-DU 174A as a MN and operates with the S-DU 174B as a SN.
  • the CU 172 may perform 880 a LTM DU configuration and/or activation procedure with the UE 102 via the M-DU 174A, similar to the procedure 380. While the UE 102 communicates in DC with the M-DU 174A and S-DU 174B, the CU 172 may perform 881 an LTM DU configuration and/or activation procedure with the UE 102 via the S-DU 174A, similar to the procedure 581 or 582.
  • a scenario 800B is similar to the scenarios 300-700B and 800 A, except that that the CU 172 transmits 817, 819 the RRC reconfiguration message to the UE 102 via the M-DU 174A and receives 821, 823 the RRC reconfiguration complete message from the UE 102 via the M-DU 174A.
  • FIGs. 9A-16B show several example methods that may be implemented in a RAN node including a DU and/or a CU, to support LTM based on TCI state configurations. Examples and embodiments described for FIGs. 3-8B may apply or be combined with the embodiments illustrated in FIGs. 9A-16B.
  • FIG. 9A illustrates an example method 900 A, which may be implemented by a CU (e.g.. the CU 172 of the first BS 104 or second B 106), for enabling LTM for a UE (e.g.. the UE 102).
  • the method 900A begins at block 902, where the CU performs a first procedure for LTM for a UE with a first DU (e.g., events 308, 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690. 681, 780, 790, 880, 890, or 881).
  • the CU receives 904 a first LTM DU configuration for configuring a first cell for LTM.
  • the CU transmits 906 a first message including the first LTM DU configuration to the UE via a RAN node (e.g., events 316, 318, 394, 380, 480, 494, 580. 594, 581, 517, 519, 582, 680. 694, 681, 617, 619, 780. 794, 781, 717, 719, 880, 894, 881. 817, or 819).
  • a RAN node e.g., events 316, 318, 394, 380, 480, 494, 580. 594, 581, 517, 519, 582, 680. 694, 681, 617, 619, 780. 794, 781, 717, 719, 880, 894, 881. 817, or 819.
  • the CU performs 908 a second procedure for LTM change for the UE with the first DU (e.g., events 312, 314, 392, 380, 492, 480, 580, 592, 581, 582, 680, 692, 681, 780, 792, 880, 892, or 881).
  • the CU receives 910 at least one first TCI state configuration from the first DU during the second procedure (e.g., events 314, 392, 380, 492, 480, 580, 592, 581, 582. 680, 692, 681, 780, 792. 880, 892, or 881).
  • each of the first TCI state configuration(s) configures a TCI state for the UE to transmit and/or receive data and/or control signal on the first cell.
  • the CU transmits 912 the first TCI state configuration(s) to a second DU (e.g., events 412, 493, 693, and 893).
  • the CU transmits 914 a second message including the first TCI state configuration(s) to the UE via the RAN node (e.g., events 316, 318, 394. 380, 480, 494, 580, 594. 581, 517, 519, 582, 680. 694, 681.
  • the CU includes the first TCI state configuration(s) in a LTM configuration IE and includes the LTM configuration IE in the second message.
  • the LTM configuration IE includes the first LTM DU configuration.
  • the CU receives 916 an indication message from the first DU, indicating that the UE successfully accesses the first cell after transmitting the first message and the second message to the UE (e.g., events 334. 354, 398, 380, 434, 454. 498, 480. 580, 534, 598, 581, 582, 680, 634, 698, 681, 780, 734, 798, 880, 881, 834, or 898).
  • the CU communicates 918 with the UE, via the first DU and the first cell using the first TCI state configuration (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836. 856, 880, or 881).
  • the first TCI state configuration e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836. 856, 880, or 881).
  • one of the first DU and the second DU is a serving DU and the other is a target DU (i.e.. a candidate DU).
  • the first DU and the second DU are target DUs (i.e., candidate DUs).
  • the RAN node is a serving DU (e.g., the first DU, the second DU or a third DU), and the CU communicates with the UE via the serving DU and a serving cell operated by the serving DU.
  • the RAN node is a BS that communicates with the UE.
  • the BS is an MN and the CU is a CU of a SN.
  • the BS is an SN and the CU is a CU of a MN.
  • the CU receives a first DU-to-CU message including the first LTM DU configuration from the first DU.
  • the CU receives a second DU-to-CU message including the first TCI state configuration(s) from the first DU.
  • the first DU generates a serving DU configuration (e.g., RRC CeHGroupConflg IE) including the first TCI state configuration(s) and includes the serving DU configuration in the second DU-to-CU message.
  • the first DU includes the first TCI state configuration(s) in the first LTM DU configuration.
  • the first DU includes the first TCI state configuration(s) in the serving DU configuration and the first LTM DU configuration.
  • “the first TCI state configuration(s)” may be replaced by "‘the serving DU configuration” or ’‘the first LTM DU configuration”.
  • the first DU-to-CU message and the second DU-to-CU message are the same message (i.e., the same instance). In other embodiments, the first DU- to-CU message and the second DU-to-CU message are separate messages.
  • the first DU-to- CU message or the second DU-to-CU message may be a UE Context Setup Response message, a UE Context Modification Response message, or a UE C ontext Modification Required message as described below.
  • the first DU-to-CU message includes the first LTM DU configuration in a first interface protocol lE/field and the second DU-to- CU message includes the first TCI state configuration(s) in a second interface protocol lE/field.
  • the first interface protocol lE/field is a first Fl AP lE/field and the second interface protocol lE/field is a second F1AP lE/field.
  • one of the first F1AP lE/field and the second F1AP lE/field is an F1AP CellGroupConfig lE/field and the other is not the F1AP CellGroupConfig lE/field.
  • neither the first Fl AP lE/field nor the second Fl AP IE is F1AP CellGroupConfig IE field.
  • the second F1AP lE/field is a DU to CU RRC Information IE and the first Fl AP lE/field is a new IE specific for including a LTM DU configuration.
  • the CU transmits 912 a third CU-to-DU message including the first TCI state configuration(s) to the second DU.
  • the CU includes the first LTM DU configuration in the third CU-to-DU message.
  • the second DU retrieves the first TCI state configuration(s) from the first LTM DU configuration.
  • the second DU transmits a third DU-to-CU message to the CU, in response to the third CU-to-DU message.
  • the CU includes the first TCI state configuration(s) or the first LTM DU configuration in an interface protocol TE/field and includes the interface protocol lE/field in the third CU-to-DU message.
  • the interface protocol field/IE is a CU to DU RRC Information IE.
  • the interface protocol field/IE is a Fl AP CellGroupConfig IE.
  • the CU includes the Fl AP CellGroupConfig IE in the CU to DU RRC Information IE and includes the CU to DU RRC Information IE in the third CU-to-DU message.
  • the CU includes an indication in the third CU-to-DU message to indicate that the first TCI state configuration(s) or the first LTM DU configuration is for LTM.
  • the interface protocol field/IE is a new interface protocol field/IE for LTM.
  • the new interface protocol field/IE is defined in a 3GPP TS.
  • the CU includes the new interface protocol field/IE in a CU to DU RRC Information IE in the third CU-to-DU message.
  • the CU includes the new interface protocol field/IE outside the CU to DU RRC Information IE.
  • the third CU-to-DU message and the third DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Response message, respectively.
  • the third CU-to-DU message and the third DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Required message, respectively.
  • the third CU-to-DU message and the third DU-to-CU message are a UE Context Setup Request message and a UE Context Setup Response message, respectively.
  • the first message and the second message are RRC reconfiguration messages.
  • the first message and the second message may be combined as a single message, i.e., the first message and the second message are the same message. In other embodiments, the first message and the second message are separate messages.
  • the first LTM DU configuration includes the first TCI state configuration(s), and the CU receives the first TCI state configuration(s) in the first LTM DU configuration.
  • the CU retrieves the first TCI state configuration(s) from the first LTM DU configuration and includes the first TCI state configuration(s) in the second message.
  • the first LTM DU configuration includes the first TCI state configuration(s), and the CU receives the first TCI state configuration(s) in the second DU-to-CU message.
  • the first DU includes the first TCI state configuration(s) in the second interface protocol lE/field in the second DU-to-CU message in addition to including the first TCI state configuration(s) in the first LTM DU configuration.
  • the first procedure is a UE Context Setup procedure or a UE Context Modification procedure.
  • the UE Context Modification procedure may be initiated by the CU or the first DU.
  • the CU transmits a UE Context Setup Request message and receives a UE Context Setup Response message including the first LTM DU configuration from the first DU, in response.
  • the CU transmits a UE Context Modification Request message and receives a UE Context Modification Response message including the first LTM DU configuration from the first DU, in response.
  • the CU receives a UE Context Modification Required message including the first LTM DU configuration from the first DU and transmits a UE Context Modification Confirm message to the first DU, in response.
  • the second procedure is a UE Context Setup procedure or a UE Context Modification procedure.
  • the UE Context Modification procedure may be initiated by the CU or the first DU.
  • the CU transmits a UE Context Setup Request message and receives a UE Context Setup Response message including the first TCI state configuration(s) from the first DU, in response.
  • the CU transmits a UE Context Modification Request message and receives a UE Context Modification Response message including the first TCI state configuration(s) from the first DU.
  • the CU receives a UE Context Modification Required message including the first TCI state configuration(s) from the first DU and transmits a UE Context Modification Confirm message to the first DU.
  • the first and second procedures may be combined as a single procedure, i.e., the first procedure and the second procedure are the same procedure and the first DU-to-CU message and the second DU-to-CU message are the same DU-to-CU message (e.g., a UE Context Setup Response message, a UE Context Modification Response message, or a UE Context Modification Required message as described below).
  • the CU receives the first LTM DU configuration and the first TCI state configuration(s) from the first DU in the procedure.
  • the CU transmits a UE Context Setup Request message and receives a UE Context Setup Response message including the first LTM DU configuration and the first TCI state configuration(s) from the first DU, in response.
  • the CU transmits a UE C ontext Modification Request message and receives a UE Context Modification Response message including the first LTM DU configuration and the first TCI state configuration(s) from the first DU.
  • the CU receives a UE Context Modification Required message including the first LTM DU configuration and the first TCI state configuration(s) from the first DU and, in response, transmits a UE Context
  • the first interface protocol lE/field and the second interface protocol lE/field are included in a parent lE/field (e.g., DU to CURRC Information lE/field) in the DU-to-CU message.
  • a parent lE/field e.g., DU to CURRC Information lE/field
  • one of the first interface protocol lE/field and the second interface protocol lE/field are included in the parent lE/field and the other is not included in the parent lE/field.
  • neither the first interface protocol lE/field nor the second interface protocol lE/field are included in the same parent IE.
  • the CU transmits a CU-to-DU message including the first TCI state configuration(s) to the serving DU (e.g., the second DU or the third DU) (e.g., events 412, 493, 693. 893).
  • the CU receives a DU-to-CU message from the serving DU, in response. Otherwise, if the first DU is the serving DU, the CU does not transmit the first TCI state configuration(s) to the serv ing DU.
  • the CU-to-DU message and the DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Response message, respectively.
  • each of the first TCI state configuration(s) includes a TCI state ID identifying the corresponding TCI state configuration.
  • the serving DU transmits a first LTM command to the UE, where the first LTM command requests the UE to connect the first cell (e.g., events 330, 380, 430, 480, 530, 580, 581, 582, 680, 681, 630, 780, 730, 880, 881, or 830).
  • the UE disconnects from a serving cell operated by the serving DU and connects to the first cell and communicates on the first cell with the first DU (e.g., events 336. 380, 436, 480, 536, 580, 581, 582, 636, 680, 681, 736, 780, 836, 880, or 881).
  • the first TCI state configuration(s) includes TCI state configuration(s) 1, ..., L, where L is a positive integer and larger than zero.
  • the TCI state configuration(s) 1, . . . , L may include TCI state ID(s) 1, ...
  • the serving DU includes the TCI state ID 1 in the first LTM command to request the UE to apply the TCI state configuration 1 to communicate on the first cell.
  • the UE accesses and/or communicates on the first cell using the TCI state configuration 1 in accordance with the TCI state ID 1 after (e.g., in response to) receiving the first LTM command.
  • the first DU detects that the UE accesses the first cell and communicates with the UE on the first cell, based on the TCI state configuration 1.
  • the serving DU includes the TCI state ID 2 in the first LTM command to indicate to the UE to apply the TCI state configuration 2 to communicate on the first cell, in addition to the TCI state ID 1 .
  • the UE accesses and/or communicates on the first cell using the TCI state configurations 1 and 2 in accordance with the TCI state ID 1 and the TCI state ID 2.
  • the first DU detects that the UE accesses the first cell and communicates with the UE on the first cell, based on the TCI state configuration 1 and the TCI state configuration 2.
  • the UE may skip a random access procedure and directly transmits the first transmission (e.g., a PUSCH transmission or a PUCCH transmission) on the first cell using the first TCI state configuration(s).
  • the first DU receives the first transmission from the UE on the first cell using the first TCI state configuration(s).
  • the serving DU might not include a TCI state ID in the first LTM command, and the UE communicates on the first cell with the first DU using the at least one first TCI state, after (e.g., in response to) receiving the first LTM command.
  • the first DU detects that the UE accesses the first cell and communicates with the UE on the first cell, based on the first TCI state configuration(s). For example, the UE may skip a random access procedure and directly transmits the first transmission (e.g., a PUSCH transmission or a PUCCH transmission) on the first cell to the DU 174, in response to receiving the first LTM command.
  • the first DU receives the first transmission from the UE using the first TCI state configuration(s).
  • the serving DU includes a first ID identifying the first cell or the first LTM configuration in the first LTM command, where the first ID may be a first cell ID, a first cell index, or a first LTM ID.
  • the serving DU receives the ID and/or the first LTM DU configuration from the CU.
  • the serving DU includes a timing advance value in the first LTM command.
  • the serving DU transmits a DCI (e.g., a PDCCH order) on the serving cell to the UE to order the UE to transmit a preamble (e.g., a random access preamble) on the first cell before transmitting the first LTM command.
  • a DCI e.g., a PDCCH order
  • the UE After (e.g., in response to) the DCI, the UE transmits the preamble on the first cell.
  • the first DU determines the timing advance value by measuring the time the first DU takes to receive the preamble (i.e., propagation delay).
  • the UE disconnects from the serving cell and accesses the first cell using the timing advance value.
  • the UE applies the timing advance value in one or more uplink transmissions on the first cell to the first DU.
  • the serving DU before transmitting the first LTM command, might transmit one or more activation commands to activate the TCI state configured on(s) 1, ..., K.
  • K is a positive integer and 1 ⁇ K ⁇ L.
  • K is 1 or 2.
  • K is equal to L.
  • the UE determines that the TCI state configuration(s) 1, . . . , K is/are activated upon receiving the activation command(s).
  • each of the activation command(s) is a MAC CE.
  • each of the activation command(s) is a DCI.
  • the serving DU includes or indicates the TCI state ID(s) 1, K in the activation command(s).
  • the serving DU when the serving DU determines to send an LTM command (e.g.. the first LTM command) for the UE to command the UE to perform a fast serving change to a target cell (e.g., the first cell), the serving DU only includes, in the LTM command (e.g., the first LTM command), one or more TCI state IDs (e.g.. one, some or all of the TCI state ID(s) 1, .. . , K) for one or more TCI state configurations (e.g., the TCI state configuration(s) 1, . . . , K) that the serving DU has activated for the UE.
  • the LTM command e.g. the first LTM command
  • TCI state IDs e.g. one, some or all of the TCI state ID(s) 1, .. . , K
  • TCI state configurations e.g., the TCI state configuration(s) 1, . . . , K
  • the serving DU refrains from including, in a LTM command for the UE, a TCI state ID for a TCI state configuration that the serving DU has not activated for the UE.
  • the DU 174 includes the first cell ID or the first cell index in the activation command(s). Based on the first cell ID or the first cell index, and the one or more TCI state IDs in the activation command(s), the UE determines that the activation command(s) activates the one or more TCI state configurations in the first TCI state configuration(s), where each of the TCI state ID(s) identifies a particular TCI state configuration of the TCI state configuration(s).
  • the first LTM DU configuration includes the first TCI state configuration(s), and the CU receives 908 the first TCI state configuration(s) in the (second) DU-to-CU message.
  • the first DU includes the first TCI state configuration(s) in the (second) interface protocol lE/field in the (second) DU-to-CU message in addition to including the first TCI state configuration(s) in the first LTM DU configuration.
  • the first DU After detecting that the UE accessed the first cell, the first DU performs communication of PUSCH transmissions. PDSCH transmissions. PUCCH transmissions, PDCCH transmissions, and/or SRS transmissions with the UE.
  • the first DU performs communication with the UE, using the first TCI state configuration(s).
  • the first DU includes additional TCI state configurations in the first LTM DU configuration.
  • the first DU uses some or all of the additional TCI state configurations to perform communication of PUSCH transmissions, PDSCH transmissions, PUCCH transmissions, PDCCH transmissions, and/or SRS transmissions with the UE.
  • the CU performs a third procedure for LTM for the UE with the first DU and receives at least one first RS resource configuration from the first DU in the third procedure.
  • the CU receives a third DU-to-CU message including the first RS resource configuration(s) from the first DU.
  • the third procedure may be a UE Context Setup procedure, or a UE Context Modification procedure as described above, and the third DU-to-CU message is a UE Context Setup Response message, a UE Context Modification Response message, or a UE Context Modification Required message.
  • each of the first RS resource configuration(s) configures one or more RSs and/or one or more RS resources.
  • the RS may be a SSB or a CSI-RS.
  • each of the first RS resource configuration(s) is aNZP-CSI-RS-Resource IE, a NZP-CSI-RS-ResourceSet IES, and/or a CSI-SSB-ResourceSet IE.
  • the CU transmits a fourth CU-to-DU message including the at least one first RS resource configuration to the second DU.
  • the second DU Based on the at least one first RS resource configuration, the second DU generates at least one first report configuration for reporting measurement results of the RS(s) or RS resource(s).
  • the first report configuration(s) configures UL resources (e.g., PUCCH resources or PUSCH resources) for transmission of measurement results.
  • each of the measurement results includes an RS resource indicator and/or a quantized measurement value.
  • the RS resource indicator is an SSB resource indicator or a CSI-RS resource indicator.
  • the quantized measurement value might be an Ll-RSRP or an Ll-SINR.
  • the second DU transmits a fourth DU-to-CU message including the first report configuration(s) to the CU.
  • the CU then transmits a third message including the first report configuration(s) to the UE 102 via the serving DU or the RAN node.
  • each of the first report configuration(s) includes a resource configuration ID identifying a particular RS resource configuration in the at least one first RS resource configuration.
  • each of the first report configuration(s) is a CSI-ReportConfig IE.
  • the first reporting configuration(s) is/are similar to the LI measurement report configuration(s) described above.
  • the CU includes the first RS resource configuration(s) in the third message.
  • the second DU includes the first report configuration(s) in a DU configuration (e.g., a RRC CellGroupConfig IE) and includes the DU configuration in the fourth DU-to-CU message.
  • the fourth CU-to- DU message is a UE Context Modification Request message
  • the fourth DU-to-CU message is a UE Context Modification Response message or a UE Context Modification Required message.
  • the second DU includes the first RS resource configuration(s) in the DU configuration.
  • the serving DU does not include the first RS resource configurations in the serving DU configuration.
  • the second DU includes the DU configuration in a DU to CU RRC Information IE in the fourth DU-to-CU message.
  • the second DU includes the serving DU configuration in an interface protocol lE/field (e.g., F1AP CellGroupConfig lE/field) and includes the interface protocol UE/field in the fourth DU-to-CU message.
  • the CU After receiving the fourth DU-to-CU message, the CU transmits a third message including the DU configuration to the UE 102 via the serving DU or the RAN node.
  • the second DU is a serving DU
  • the DU configuration is a serving DU configuration
  • the CU includes the serving DU configuration in the third message.
  • the CU refrains from including the serving DU configuration in an LTM configuration.
  • the DU configuration is a (second) LTM DU configuration
  • the CU includes the LTM DU configuration in an LTM configuration in the third message.
  • the first report configuration(s) may be replaced by “the serving DU configuration” or “the (second) LTM DU configuration”.
  • the third message is a RRC reconfiguration message similar to the RRC reconfiguration message in the event 316. 318, 394. 380, 480, 494, 580, 594. 581, 517, 519, 582, 680, 694, 681, 617, 619, 780, 794, 781, 717, 719, 880, 894, 881, 817, or 819.
  • the third message is a RRC reconfiguration message in the event 316, 318, 394, 380, 480, 494, 580, 594, 581, 517, 519, 582, 680, 694, 681, 617, 619, 780, 794, 781, 717. 719, 880, 894, 881, 817, or 819.
  • the CU receives the first RS resource configuration(s) from the first DU in the first procedure or the first DU-to-CU message.
  • the first DU includes the first RS resource configuration(s) in the first LTM DU configuration.
  • the CU might receive 908 the first RS resource configuration(s) in the first LTM DU configuration.
  • the first DU includes the first LTM DU configuration in the first interface protocol lE/field and includes the first RS resource configuration(s) in the second interface protocol lE/field in the first DU-to-CU message.
  • the CU receives the first RS resource configuration(s) from the first DU in the second procedure or the second DU-to-CU message.
  • the first DU includes the first TCI state configuration(s) and the first RS resource configuration(s) in the second interface protocol lE/field in the first DU-to-CU message.
  • the first DU includes the first TCI state configuration(s) and the first RS resource configuration(s) in the second interface protocol lE/field and a third interface protocol lE/field (e.g., F1AP lE/field) in the first DU-to-CU message, respectively.
  • a third interface protocol lE/field e.g., F1AP lE/field
  • the CU includes the first RS resource configuration(s) and/or the first report configuration(s) in the first message. In other alterative embodiments, the CU includes the first RS resource configuration(s) and/or the first report configuration(s) in the second message.
  • the CU transmits the first TCI state configuration(s) to the serving DU (e g., the second DU). Otherwise, if the first DU is the serving DU. the CU does not transmit the first TCI state configuration(s) to the first DU. In some embodiments, if the first DU is a target DU (i.e., the first DU is not a serving DU), the CU transmits the at least one first RS resource configuration to the serving DU (e.g., the second DU).
  • the CU does not transmit the at least one first RS resource configuration to the first DU.
  • the serving DU and the first DU are the S-DU 174A and the T-DU 174B in FIGs. 4, 6A, and 6B, respectively.
  • the serving DU and the first DU are the S-DU 174B and the T-DU 174C in FIGs. 8A and 8B, respectively.
  • the CU receives a first additional LTM DU configuration and at least one first additional TCI state configuration from the first DU in the first DU-to- CU message and the second DU-to-CU message, respectively.
  • the CU performs one or more additional procedures with the first DU similar to the first and/or second procedure(s).
  • the CU receives one or more additional DU-to-CU messages including the first additional LTM DU configuration and at least one first additional TCI state configuration from the first DU, similar to the first and/or second DU-to-CU message(s).
  • the first additional LTM DU configuration configures a first additional cell for LTM for the UE.
  • the CU includes the first additional LTM DU configuration and the at least one first additional TCI state configuration in the first message and the second message, respectively.
  • the CU includes the first additional LTM DU configuration and the at least one first additional TCI state configuration in the first message.
  • the CU transmits one or more additional messages including the first additional LTM DU configuration and the at least one first additional TCI state configuration, to the UE, via the RAN node.
  • the additional message(s) is/are RRC reconfiguration message(s).
  • the CU transmits the at least one first additional TCI state configuration to the second DU and/or the serving DU.
  • the CU includes the at least one first additional TCI state configuration in the third CU-to-DU message. In another embodiment, the CU transmits a fourth CU-to-DU message including the at least one first additional TCI state configuration to the second DU and/or the serving DU. similar to the third CU-to-DU message.
  • the first DU i.e., a serving DU
  • the first DU might transmit an additional LTM command to the UE, where the additional LTM command requests the UE to connect to a first additional cell (e.g., events 350, 398, 380, 450, 498, 480, 598, 580, 581, 582, 680, 681, 698, 780, 798, 880, 881, or 898).
  • the UE disconnects from the first cell and connects to the first additional cell and communicates on the first additional cell with the first DU (e.g., events 356, 380, 456, 480, 556, 580, 581, 582, 656, 680, 681, 756, 780, 856, 880, or 881).
  • the at least one first additional TCI state configuration includes TCI state configuration(s) L+l, .... L+M, where L and M are positive integers.
  • the TCI state configuration(s) L+l, ... , L+M include TCI state ID(s) L+l, ...
  • the first DU includes the TCI state ID L+l in the additional LTM command to indicate to the UE to apply the TCI state configuration L+l to communicate on the first additional cell.
  • the UE communicates on the first additional cell using the TCI state configuration L+l in accordance with the TCI state ID L+l in response to the additional LTM command.
  • the first DU includes the TCI state ID L+2 in the additional LTM command to request the UE to apply the TCI state configuration L+2 to communicate on the first additional cell, in addition to the TCI state ID L+L
  • the UE communicates on the first additional cell with the first DU, using the TCI state configurations L+l and L+2 in accordance with the TCI state ID L+l and TCI state ID L+2 after (e.g., in response to) receiving the additional LTM command.
  • the first DU might not include a TCI state ID (e.g., the TCI state ID 1) in the additional LTM command, and the UE communicates on the first additional cell with the first DU using the at least one first additional TCI state, after (e.g., in response to) receiving the additional LTM command.
  • the first DU includes an additional ID identifying the first additional cell or the first additional LTM configuration in the additional LTM command, where the additional ID may be an additional cell ID, an additional cell index, or an additional LTM ID.
  • the first DU receives the additional ID from the CU.
  • the first DU before transmitting the additional LTM command, might transmit one or more activation commands to activate the TCI state configuration(s) L+l, .... L+N.
  • N is a positive integer and 1 ⁇ N ⁇ M.
  • N is 1 or 2.
  • the UE activates the TCI state configuration(s) L+l, .. . , L+N after (e.g., in response to) receiving the activation command(s).
  • each of the activation command(s) is a MAC CE.
  • each of the activation command(s) is a DCI.
  • the first DU includes or indicates the TCI state ID(s) L+l, . . .
  • the first DU when the first DU determines to send an LTM command for the UE to request the UE to perform a fast serving change/switch to a target cell (e.g., the first additional cell), the first DU only includes, in the LTM command (e.g., the additional LTM command), one or more TCI state configurations (e.g.. one, some, or all of the TCI state configuration(s) L+l, . . . , L+N) that the first DU has activated for the UE. In other words, the first DU refrains from including or indicating, in a LTM command for the UE, a TCI state ID for a TCI state configuration that the first DU has not activated for the UE.
  • the LTM command e.g., the additional LTM command
  • TCI state configurations e.g. one, some, or all of the TCI state configuration(s) L+l, . . . , L+N
  • the CU receives a second additional LTM DU configuration and at least one second additional TCI state configuration from the second DU or the third DU.
  • the third LTM DU configuration configures a second additional cell for LTM for the UE.
  • the CU transmits the second additional LTM DU configuration and the at least one second additional TCI state configuration to the UE, similar to blocks 902-910 and 914.
  • the CU might transmit the at least one second additional TCI state configuration to the first DU and/or other DU(s), similar to block 912.
  • the CU then might receive an indication message from the second DU or the third DU, indicating that the UE successfully accesses the second additional cell, similar to block 916.
  • each of the TCI state configuration(s) above associates one or two DL RSs with a corresponding QCL type.
  • the DL RS(s) is/are transmitted on a cell, (each) TCI state configuration includes a QCL information IE (e.g.. for QCL type 1).
  • the (each) TCI state configuration further includes an additional QCL information IE (e.g., for QCL type 2) and/or an additional physical cell identity (PCI) index.
  • the (each) TCI state configuration further configures a UL power control configuration and/or a pathloss RS.
  • the (each) TCI state configuration includes a UL power control ID and a pathloss RS ID identifying the UL power control configuration and/or the pathloss RS, respectively.
  • the QCL information includes configurations such as a serving cell index, a bandwidth part (BWP) ID, an RS ID, and/or a QCL ty pe.
  • the RS ID indicates an RS where the QCL information is associated.
  • the RS ID is a CSI-RS ID (e.g., NZP-CSI-RS-Resourceld) and RS may be a CSI-RS (e.g., NZP-CSI-RS-Resource) indicated by the CSI-RS ID.
  • the RS ID is an SSB index and the RS is an SSB indicated by the SSB index.
  • the serving cell index indicates a cell where the RS is configured.
  • the BWP ID indicates a BWP where the RS is located.
  • the BWP belongs to the cell.
  • the cell is the first cell in the first TCI state configuration(s).
  • the cell is the first additional cell in the at least one first additional TCI state configuration.
  • the cell is the second additional cell in the at least one second additional TCI state configuration.
  • the QCL ty pe is type A, type B, ty pe C, or type D.
  • the (each) TCI state configuration includes a TCI state ID to identify 7 the (each) TCI state configuration as described above.
  • the additional QCL information includes similar configurations as described above and has different values for these configurations from the QCK information. For example, the QCL information and the additional QCL information have the same RS ID (value) and different QCL ty pes in a TCI state configuration.
  • the at least one (first, first additional, or second additional) TCI state configuration'’ includes an ul-TCI-ToAddModList-r 17 field, one or more TCI-UL-State-rl7 IES, a dl-OrJointTCI-StateToAddModList-r 17 field, one or more TCI-State IES, TCI- ActivatedConfig IE, and/or a tci-StatesToAddModList field.
  • FIG. 9B is a flow diagram of an example method 900B similar to the method 900A, except that method 900B includes blocks 913 and 915 instead of block 914.
  • the CU receives 913 at least one second TCI state configuration from the second DU.
  • the CU receives a DU-to-CU message including the second TCI state configuration(s) from the second DU (e.g., events 414, 493, 693, or 893).
  • the DU-to-CU message is similar to the third DU-to-CU message described in FIG. 9A.
  • the second DU is the serving DU as described in the embodiment for FIG. 9A.
  • the second DU is not the serving DU as described for FIG. 9A.
  • the CU transmits 915 a second message including the second TCI state configuration(s) to the UE via the RAN node (e.g., events 316, 318, 394, 380, 480, 494, 580, 594, 581, 517, 519, 582, 680, 694, 681, 617, 619, 780, 794, 781, 717, 719, 880, 894, 881, 817, or 819).
  • the CU includes the second TCI state configuration(s) in a non-LTM field (e.g., amasterCellGroup field or a secondaryCellGroup field) in the second message.
  • a non-LTM field e.g., amasterCellGroup field or a secondaryCellGroup field
  • the second DU generates the second TCI state configuration(s) based on the first TCI state configuration(s).
  • the second DU retrieves each TCI state configuration (e.g., QCL information, additional QCL information, PCI index, UL power control ID, and/or pathloss RS ID) from the first TCI state configuration(s) and, includes each TCI state configuration in the second TCI state configuration(s).
  • the second DU assigns a value to a TCI state ID and includes the TCI state ID in the corresponding TCI state configuration.
  • the second DU does not use value(s) of the TCI state ID(s) in the first TCI state configuration(s).
  • the second DU receives 912 the first LTM DU configuration including the first TCI state configuration(s) from the CU.
  • the second DU decodes the first LTM DU configuration to obtain the first TCI state configuration(s) and retrieves each TCI state configuration from the first TCI state configuration(s).
  • the second DU generates the second TCI state configuration(s) including each TCI state configuration in the first TCI state configuration(s).
  • the second DU generates the second TCI state configuration(s) identical to the first TCI state configuration(s).
  • the second DU generates the second TCI state configuration(s) based on the first TCI state configuration(s), as described above.
  • the second DU might generate a DU configuration including the second TCI state configuration(s) and transmits the DU configuration to the CU.
  • the second DU includes the DU configuration in the DU-to-CU message.
  • the DU configuration is an RRC IE (e.g.. a RRC CellGroupConflg IE defined in 3GPP TS 38.331).
  • the DU configuration is a serving DU configuration and the CU includes the serving DU configuration in the second message. The CU refrains from including the serving DU configuration in an LTM configuration.
  • the DU configuration is an (second) LTM DU configuration
  • the CU includes the LTM DU configuration in an LTM configuration in the second message.
  • FIG. 10 illustrates an example method 1000, which may be implemented by a CU (e.g., the CU 172 of the first BS 104 or second BS 106), for transmitting a TCI state configuration to a DU to enable LTM for a UE (e.g., the UE 102).
  • a CU e.g., the CU 172 of the first BS 104 or second BS 106
  • LTM for a UE
  • the method 1000 begins with the CU receiving 1002 at least one first TCI state configuration for a UE from a first DU (e.g., events 314, 392, 380, 492. 480, 580, 592, 581, 582, 680. 692, 681, 780. 792, 880. 892, or 881).
  • the CU determines 1004 whether the first DU is communicating with the UE. If the CU determines 1004 that the first DU is not communicating with the UE (i.e., the first DU is not a serving DU of the UE), the CU transmits 1006 the first TCI state configuration(s) to a serving DU of the UE (e.g., events 412, 493.
  • the CU determines 1004 that the first DU is communicating with the UE (i.e., the first DU is a serving DU of the UE), the CU refrains 1008 from transmitting the first TCI state configuration(s) to the serving DU.
  • Descriptions for FIGs. 9A and 9B may apply to FIG. 10.
  • FIG. 11 illustrates an example method 1100, which may be implemented by a first DU (e.g., the DU 174, 174A, 174B, or 174C of the first BS 104 or second BS 106 in FIGs. 3- 8B), for enabling LTM for a UE (e.g., the UE 102).
  • a first DU e.g., the DU 174, 174A, 174B, or 174C of the first BS 104 or second BS 106 in FIGs. 3- 8B
  • LTM for enabling LTM for a UE
  • the method 1100 begins with the first DU performing 1102 a first procedure for LTM for the UE with a CU (e.g., events 308, 310. 390, 380, 490. 480, 580. 590, 581. 582. 680, 690, 681, 780, 790, 880, 890, or 881).
  • the first DU transmits 1104 a first LTM DU configuration configuring a first cell for LTM, to the CU, in the first procedure (e.g., events 310, 390. 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790. 880, 890, or 881).
  • the first DU transmits 1106 the first LTM DU configuration to the UE.
  • the first DU receives a first message including the first LTM DU configuration from the CU and transmits the first message to the UE (e.g., events 316, 318, 394, 380, 580, 594, 581, 582, 780, 794, or 781).
  • the first DU performs 1108 a second procedure for LTM for the UE with the CU (e.g., events 312. 314, 392, 380, 492, 480. 580, 592, 581, 582, 680, 692, 681. 780, 792, 880, 892, or 881).
  • the first DU transmits 1 110 at least one first TCI state configuration to the CU in the second procedure (e.g., events 314, 392, 380, 492, 480, 580, 592, 581, 582,
  • each of the first TCI state configuration(s) configures a TCI state for the UE to transmit and/or receive data and/or control signal on the first cell.
  • the first DU transmits 1112 the first TCI state configuration(s) to the UE.
  • the first DU receives a second message including the first TCI state configuration(s) from the CU and transmits the second message to the UE (e.g., events 316. 318, 394, 380, 580, 594. 581, 582, 780, 794, or 781).
  • the first DU detects 1114 that the UE accessed the first cell (e.g., events 332, 352. 398, 380, 432. 452, 498. 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, or 898).
  • the first DU detects that the UE accesses the first cell, based on one, some, or all of the first TCI state configuration(s).
  • the first DU transmits 1116 an indication message to the CU, indicating that the UE successfully accesses the first cell (e.g...
  • the first DU communicates 1118 with the UE via the first cell using the first TCI state configuration(s) (e.g., events 336, 356, 380, 436, 456, 480, 536, 556. 580,
  • FIGs. 9A and 9B Examples and embodiments described for FIGs. 9A and 9B may apply to FIG. 11.
  • FIG. 12A illustrates an example method 1200 A, which may be implemented by a DU (e.g.. the DU 174, 174A, 174B, or 174C of the first BS 104 or second BS 106 in FIGs. 3- 8B), for enabling LTM for a UE (e.g., the UE 102).
  • a DU e.g.. the DU 174, 174A, 174B, or 174C of the first BS 104 or second BS 106 in FIGs. 3- 8B
  • LTM for enabling LTM for a UE (e.g., the UE 102).
  • the method 1200A begins with the DU communicating 1202 with the UE and a CU (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, 780, 880, or 881).
  • the DU receives 1204 a first CU-to-DU message from a CU to request preparing a first cell for LTM for the UE (e.g., events 308, 390, 380, 490, 480, 580, 590, 581,
  • the DU generates 1206 a first LTM DU configuration configuring the first cell.
  • the DU generates 1208 at least one first TCI state configuration for configuring at least one TCI state.
  • the DU transmits 1210 a first DU-to-CU message including the first LTM DU configuration and the at least one first TCI state configuration to the CU (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690,
  • the DU transmits 1212 a first LTM command to the UE, commanding the UE to switch to the first cell using an LTM procedure.
  • the DU detects 1214 that the UE accesses the first cell (e.g., events 332, 336. 352, 356, 380, 432, 436, 452, 456, 498, 480, 532, 536, 552, 598. 556, 580, 581, 582, 632. 636, 698, 656, 680, 681. 732, 736. 798, 756, 780, 832, 836, 898, 868, 880, or 881).
  • the DU detects that the UE accesses the first cell, using one or some of the first TCI state configuration(s).
  • the DU transmits 1216 an indication message to the CU, indicating that the UE successfully accesses the first cell (e.g., events 334. 354, 380, 398, 434, 454. 498, 480, 534, 598, 580, 581, 582. 734, 798, 780, 834, 898, 880. or 881).
  • the DU communicates 1218 with the UE via the first cell, using the first TCI state configuration(s) (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, or 881).
  • first TCI state configuration(s) e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, or 881).
  • the DU includes the first LTM DU configuration in a first interface protocol IE or field (lE/field) in the first DU-to-CU message.
  • the DU includes the first TCI state configuration(s) in a second interface protocol lE/field in the first DU-to-CU message.
  • one of the first interface protocol lE/field and the second interface protocol lE/field is a Fl AP CellGroupConfig lE/field and the other is different from the Fl AP CellGroupConfig lE/field.
  • one of the first interface protocol lE/field and the second interface protocol lE/field is a DU to CU RRC Information lE/field and the other is different from the DU to CURRC Information lE/field.
  • the DU includes the first LTM DU configuration and the first TCI state configuration(s) in the different interface protocol lEs/fields, so that the CU may retrieve or identify the first LTM DU configuration and the first TCI state configuration(s) from the first interface protocol lE/field and the second interface protocol lE/field, respectively.
  • the CU may properly transmit the first LTM DU configuration and the first TCI state configuration(s) to the UE as described in FIG. 9A.
  • the DU includes the first LTM DU configuration and the first TCI state configuration(s) in an interface protocol lE/field of the first DU-to-CU message.
  • the DU includes the first LTM DU configuration and the first TCI state configuration(s) in a first child lE/field and a second child lE/field, respectively, and includes the first child lE/field and the second child lE/field in the interface protocol lE/field of the first DU-to-CU message.
  • the DU includes the first LTM DU configuration and the first TCI state configuration(s) in the different child lEs/fields, so that the CU may retrieve or identify the first LTM DU configuration and first TCI state configuration(s) from the first child TE/field and the second child lE/field, respectively.
  • the CU may properly transmit the first LTM DU configuration and the at least one first reference signal resource configuration to the UE, as described in FIG. 9A.
  • the first CU-to-DU message and the first DU-to-CU message are a UE Context Setup Request message and a UE Context Setup Response message.
  • the first CU-to-DU message and the first DU-to-CU message are a UE Context Modi fication Request message and a UE Context Modification Response message.
  • the first CU-to-DU message and the first DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Required message.
  • the DU transmits a UE Context Modification Response message to the CU in response to the UE Context Modification Request message, and the DU receives a UE Context Modification Confirm message from the CU in response to the UE Context Modification Required message.
  • the DU receives a second CU-to-DU message from the CU to request preparing a second cell for LTM for the UE (e.g.. events 310, 390, 380, 490, 480, 580, 590. 581, 582, 680, 690, 681. 780, 790, 880, 890, or 881).
  • the DU generates a second LTM DU configuration configuring the second cell, and generates at least one second TCI state configuration for at least one second TCI state.
  • the DU transmits a second DU-to-CU message, including the second LTM DU configuration and the second TCI state configuration(s), to the CU (e.g., events 310. 390, 380, 490, 480, 580, 590, 581. 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • FIG. 12B is a flow diagram of an example method 1200B similar to the method 1200A, except that the method 1200B includes blocks 1209 and 1211 instead of block 1210.
  • the DU transmits 1209 a first DU-to-CU message including the first LTM DU configuration to the CU (e.g., events 310, 390, 380, 490. 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890. or 881).
  • the DU transmits 1210 an additional DU-to-CU message including the at least one TCI state configuration to the CU.
  • the DU includes the at least one first TCI state configuration in the additional DU-to-CU message instead of the first DU- to-CU message.
  • the DU includes the first LTM DU configuration in a first interface protocol IE or field (lE/field) in the first DU-to-CU message.
  • the DU includes the first TCI state configuration(s) in a second interface protocol lE/field in the additional DU-to-CU message.
  • one of the first interface protocol lE/field and the second interface protocol lE/field is a Fl AP CellGroupConfig lE/field and the other is different from the F1AP CellGroupConfig lE/field.
  • one of the first interface protocol lE/field and the second interface protocol lE/field is DU to CU RRC Information lE/field and the other is different from the DU to CU RRC Information lE/field.
  • the DU includes the first LTM DU configuration and the first TCI state configuration(s) in the different interface protocol lEs/fields, so that the CU may retrieve or identify the first LTM DU configuration and the first TCI state configuration(s) from the first interface protocol lE/field and the second interface protocol lE/field, respectively.
  • the CU may properly transmit the first LTM DU configuration and the at least one first reference signal resource configuration to the UE, as described for FIGs. 9A-9B.
  • Examples and embodiments described for a DU (e.g., the serving DU, the first DU, or the second DU) in FIGs. 9A, 9B, and 11 may apply to the DU in FIGs. 12A and 12B.
  • FIG. 13A illustrates an example method 1300A, which may be implemented by a DU (e.g., the DU 174, 174A, 174B, or 174C in FIGs. 3 to 8B), for enabling LTM for a UE (e.g., the UE 102).
  • a DU e.g., the DU 174, 174A, 174B, or 174C in FIGs. 3 to 8B
  • LTM for enabling LTM for a UE (e.g., the UE 102).
  • the method 1300 A begins with the DU receiving 1302 at least one first TCI state configuration from the CU, where each of the at least one first TCI state configuration configures a TCI state (e.g., events 308, 390, 380, 312, 392, 490, 492, 480, 580, 590, 592,
  • a TCI state e.g., events 308, 390, 380, 312, 392, 490, 492, 480, 580, 590, 592
  • the DU receives a CU-to-DU message including the first TCI state configuration(s) from the CU.
  • each of the first TCI state configuration(s) configures a TCI state for communication on a cell of another DU (e g., a T-DU).
  • the DU generates 1304 at least one second TCI state configuration based on the at least one first TCI state configuration.
  • the DU transmits 1306 the at least one second TCI state configuration to the CU (e.g., events 310, 390. 380, 314, 392, 490, 492.
  • the DU transmits a DU-to-CU message including the second TCI state configuration(s) to the CU.
  • the DU transmits 1308 a first LTM command directing the UE to connect to a first cell to the UE, where the first LTM command includes a first TCI state ID identifying a first one of the at least one second TCI state configuration (e.g., events 330. 350, 398, 380, 430, 450. 498, 480. 580, 530, 598, 581,
  • the DU may include a second TCI ID identifying a second one of the second TCI state configuration(s) in the first LTM command.
  • the CU-to-DU message and the DU-to-CU message are a UE Context Setup Request message and a UE Context Setup Response message, respectively.
  • the CU-to-DU message and the DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Response message, respectively.
  • the DU-to-CU message is a UE Context Modification Required message.
  • the DU includes an LTM ID identifying an LTM configuration in the first LTM command.
  • the LTM ID is a cell ID of the first cell.
  • the LTM ID is a cell index indexing the first cell.
  • the LTM ID is an ID identifying a LTM configuration for communication via the first cell.
  • the CU includes the first TCI state configuration(s) in anew lE/field and includes the new lE/field in the CU-to-DU message. In some embodiments, the CU includes the new lE/field in a CU to DU RRC Information IE and includes the CU to DU RRC Information IE in the CU-to-DU message. In other embodiments, the CU does not include the new lE/field in a CUto DU RRC Information IE. In some embodiments, the CU includes the first TCI state configuration(s) in a new lE/field and includes the new lE/field in the CU-to-DU message.
  • the DU receives 1302 the CU-to-DU message including a DU configuration (e.g., a RRC CellGroupConfig IE) including the first TCI state configuration(s) from the CU.
  • the CU includes the DU configuration in a CU to DU RRC Information IE and includes the CU to DU RRC Information IE in the CU-to-DU message.
  • the DU includes the second TCI state configuration(s) in an interface protocol lE/field in the DU-to-CU message.
  • the interface protocol lE/field is a new lE/field different from a F1AP CellGroupConfig lE/field defined in 3GPP TS 38.473.
  • the DU includes the second TCI state configuration(s) in a serving DU configuration and transmits 1306 the serving DU configuration to the CU.
  • the serving DU configuration is a cell group configuration (e.g.. a RRC CellGroupConfig IE) including configuration parameters for communication between the UE and DU.
  • the DU transmits 1306 a DU-to-CU message including the serving DU configuration to the CU.
  • FIG. 13B is a flow diagram of an example method 1300B similar to the method 1300A, except that the method 1300B includes block 1307 instead of blocks 1304, 1306, and 1308.
  • the DU transmits 1307 a first LTM command directing the UE to connect to a first cell to the UE, where the first LTM command includes a first TCI state ID identifying a first one of the first TCI state configuration(s).
  • the DU may include a second TCI state ID identifying a second one of the first TCI state configuration(s) in the first LTM command.
  • Examples and embodiments described for a DU (e.g., the serving DU, the first DU, or the second DU) in FIGs. 9A, 9B, and 11-12B may apply to the DU in FIGs. 13A and 13B.
  • FIG. 14A illustrates an example method 1400A, which may be implemented by a DU (e.g.. the DU 174, 174 A, 174B, or 174C in FIGs. 3-8B), for enabling LTM for a UE (e.g., the UE 102).
  • a DU e.g.. the DU 174, 174 A, 174B, or 174C in FIGs. 3-8B
  • LTM for enabling LTM for a UE (e.g., the UE 102).
  • the method 1400A begins with the DU receiving 1402 a first CU-to-DU message from a CU to request preparing a first cell for LTM for a UE, where the first CU-to-DU message includes at least one first TCI state configuration and each of the first TCI state configuration(s) configures a TCI state (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582, 680. 690, 681, 780, 790, 880. 890, or 881).
  • each of the TCI state(s) associates one or two DL RSs with a corresponding QCL type and a cell other than the first cell.
  • the DU generates 1404 at least one second TCI state configuration based on the first TCI state configuration(s).
  • the DU generates 1406 a first LTM DU configuration for the UE to switch to the first cell using an LTM procedure.
  • the first LTM DU configuration may include the second TCI state configuration(s).
  • the DU transmits 1408 a first DU-to-CU message, including the first LTM DU configuration and the second TCI state configuration, to the CU (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • the DU retrieves each TCI state configuration (e.g., QCL information, additional QCL information, PCI index, UL power control ID, and/or pathloss RS ID) from the first TCI state configuration(s) and, includes each TCI state configuration in the second TCI state configuration(s).
  • each TCI state configuration in the second TCI state configuration(s) the DU assigns a value to a TCI state ID and includes the TCI state ID in the corresponding TCI state configuration.
  • the DU does not use value(s) of the TCI state ID(s) in the first TCI state configuration(s).
  • the DU receives a second CU-to-DU message from the CU to request preparing a second cell for LTM for the UE, where the second CU-to-DU message includes the first TCI state configuration(s) (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582. 680, 690, 681, 780, 790. 880, 890, or 881).
  • the DU generates at least one third TCI state configuration based on the first TCI state configuration(s).
  • the DU generates a second LTM DU configuration for the UE, configuring the second cell.
  • the second LTM DU configuration may include the third TCI state configuration(s).
  • the DU transmits a second DU-to-CU message including the second LTM DU configuration and the third TCI state configuration(s) to the CU (e.g.. events 310. 390, 380. 490, 480, 580. 590, 581. 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • a second DU-to-CU message including the second LTM DU configuration and the third TCI state configuration(s) to the CU (e.g. events 310. 390, 380. 490, 480, 580. 590, 581. 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • FIG. 14B is a flow diagram of an example method 1400B similar to the method 1400A, except that the method 1400B includes block 1405 instead of blocks 1404 and 1406.
  • the DU generates 1405 a first LTM DU configuration for the UE, configuring the first cell, and including the first TCI state configuration(s).
  • the DU receives a second CU-to-DU message from the CU to request preparing a second cell for LTM for the UE, where the second CU-to-DU message includes the first TCI state configuration(s) (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • the DU generates a second LTM DU configuration for the UE, configuring the second cell.
  • the DU transmits a second DU-to-CU message, including the second LTM DU configuration and the first TCI state configuration(s), to the CU (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • a second DU-to-CU message including the second LTM DU configuration and the first TCI state configuration(s)
  • the CU e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • Examples and embodiments described for a DU (e g., the serving DU, the first DU or the second DU) in FIGs. 9A, 9B, and 11-13B may apply to the DU in FIGs. 14A and 14B. Examples and embodiments described for FIGs. 14A and 14B may apply to the previous figures.
  • FIG. 15 illustrates an example method 1500, which may be implemented by a DU (e.g., a S-DU in FIGs. 4. 6A-6B. and 8A-8B), for enabling LTM for a UE (e.g., the UE 102).
  • a DU e.g., a S-DU in FIGs. 4. 6A-6B. and 8A-8B
  • LTM for enabling LTM for a UE (e.g., the UE 102).
  • the method 1500 begins with the DU communicating 1502 with the UE, using a first serving DU configuration (e.g.. events 402. 602, or 802).
  • the DU receives 1504 a first CU-to-DU message including a first LTM DU configuration configuring a first cell for LTM for the UE, from a CU (e.g., events 412, 493, 693, or 893).
  • the DU generates 1506 a second serving DU configuration based on the first LTM DU configuration and, optionally, based on a TCI state configuration(s).
  • the DU transmits 1508 a first DU-to-CU message including the second serving DU configuration and the TCI state configuration(s), to the CU (e.g., events 414, 493. 693, or 893).
  • the DU communicates 1510 with the UE in accordance with the second serving DU configuration (e.g., events 424, 436, 444, 498, 624, 698, 636, 824, 898, or 836).
  • the DU transmits 1512 a first LTM command requesting the UE to connect to the first cell (e.g., events 430, 450, 498, 630, 698, 830. or 898).
  • the DU is a serving DU.
  • the CU receives the first LTM DU configuration from a target DU (e.g., 490, 690, or 890).
  • the second serving DU configuration augments the first serving DU configuration.
  • the second serving DU configuration includes (new) configurations that do not exist in the first serving DU configuration.
  • the second serving DU configuration includes (new) configurations updating (existing) configurations included in the first serving DU configuration. Examples of the first serving DU configuration and the second serving DU configuration are similar to the serving DU configuration described above.
  • the first LTM DU configuration includes at least one first RS resource configuration and at least one first report configuration for reporting measurements of some RSs configured in the first RS source configuration(s).
  • the DU generates at least one second RS resource configuration based on the first RS resource configuration(s) and includes the second RS resource configuration(s) in the second serving DU configuration.
  • the DU generates at least one second report configuration for reporting measurement results of some RSs configured in the second RS resource configuration(s) and includes the second report configuration(s) in the second serv ing DU configuration.
  • the DU generates at least one second report configuration for reporting measurement results of some RSs configured in the first RS resource configuration(s) and includes the first RS resource configuration(s) and the second report configuration(s) in the second serving DU configuration.
  • the first serving DU configuration includes at least one third RS resource configuration and/or at least one third report configuration for reporting measurement results of some RSs configured in the third RS resource configuration(s).
  • RSs configured in the third RS resource configuration(s) are different from RSs configured in the first RS resource configuration(s) and the second RS resource configuration(s).
  • some of the third report configuration(s) are the same as the second report configuration(s).
  • the third report configuration(s) are different from the second report configuration(s).
  • the first LTM DU configuration includes at least one first TCI state configuration.
  • the DU generates at least one second TCI state configuration based on the first TCI state configuration(s) and includes the second TCI state configuration(s) in the second serving DU configuration.
  • the DU includes the first TCI state configuration(s) in the second serving DU configuration.
  • the first serving DU configuration includes at least one third TCI state configuration.
  • the CU generates an RRC message including the second serving DU configuration and transmits the RRC message to the UE via the DU, an additional DU, or a BS.
  • the CU receives an RRC response message from the UE via the DU, the additional DU, or the BS.
  • the RRC message and the RRC response message are similar to the RRC reconfiguration message and RRC reconfiguration complete message, respectively, as described in FIGs. 3-8B.
  • the DU receives a second CU-to-DU message including a second LTM DU configuration for the UE, from the CU (e.g., events 490, 480, 680, 690, 681, 880, 890, or 881).
  • the DU generates a third serving DU configuration based on the second LTM DU configuration.
  • the DU generates the third serving DU configuration, based on the second LTM DU configuration and the first serving DU configuration.
  • the DU transmits a second DU-to-CU message including the third serving DU configuration to the CU (e.g., events 490, 480, 680, 690, 681, 880, 890, or 881).
  • the DU communicates with the UE in accordance with the third serving DU configuration (e.g., events 424. 436, 444, 498, 480, 624. 698, 680, 681, 636, 880, 881, 824. 898, or 836).
  • the third serving DU configuration augments the second serving DU configuration.
  • the third serving DU configuration includes (new) configurations that do not exist in the second serving DU configuration.
  • the third serving DU configuration includes (new) configurations updating (existing) configurations included in the second serving DU configuration. Examples of the third serving DU configuration are similar to the serving DU configuration described above.
  • the second LTM DU configuration includes at least one fourth RS resource configuration and at least one fourth report configuration for reporting measurements of some RSs configured in the fourth RS source configuration(s).
  • the DU generates at least one fifth RS resource configuration based on the fourth RS resource configuration(s) and includes the fifth RS resource configuration(s) in the third serving DU configuration.
  • the DU generates at least one fifth report configuration for reporting measurement results of some RSs configured in the fifth RS resource configuration(s) and includes the fifth report configuration(s) in the third serving DU configuration.
  • the DU generates at least one fifth report configuration for reporting measurement results of some RSs configured in the fourth RS resource configuration(s) and includes the fourth RS resource configuration(s) and the fifth report configuration(s) in the third serving DU configuration.
  • RSs configured in the third RS resource configuration(s) are different from RSs configured in the fourth RS resource configuration(s) and the fifth RS resource configuration(s).
  • some of the third report configuration(s) are the same as the fifth report configuration(s).
  • the third report configuration(s) are different from the fifth report configuration(s).
  • the second LTM DU configuration includes at least one fourth TCI state configuration.
  • the DU generates at least one fifth TCI state configuration based on the fourth TCI state configuration(s) and includes the fifth TCI state configuration(s) in the third serving DU configuration.
  • the DU includes the fourth TCI state configuration(s) in the third serving DU configuration.
  • the (first or second) CU-to-DU message and the (first or second) DU-to-CU message are a UE Context Setup Request message and a UE Context Setup Response message, respectively.
  • the (first or second) CU-to-DU message and the (first or second) DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Response message, respectively.
  • the (first or second) DU-to-CU message is a UE Context Modification Required message.
  • FIG. 16 illustrates an example method 1600, which may be implemented by a DU (e.g.. the DU 174, 174A. 174B, or 174C in FIGs. 3-8B), for enabling LTM for a UE (e.g., the UE 102).
  • the method 1600 begins with the DU receiving 1 02 a first CU-to-DU message including a first LTM DU configuration for the UE, from a CU, where the first LTM DU configuration configures a first cell for LTM (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582. 680, 690, 681, 780, 790.
  • the DU generates 1604 a second DU configuration based on the first LTM DU configuration, where the second DU configuration configures a second cell for LTM.
  • the DU transmits 1606 a first DU-to-CU message including the second LTM DU configuration to the CU (e.g., events 310, 390, 380, 490, 480, 580, 590. 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • the DU detects 1608 that the UE accessed the second cell.
  • the DU transmits 1610 an indication message to the CU.
  • the DU communicates 1612 with the UE via the second cell using the second LTM configuration (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, or 881).
  • the second LTM configuration e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, or 881).
  • the DU is a serving DU which may be a source DU or a secondary 7 DU as described in FIGs. 4, 6A-6B, and 8A-8B.
  • the DU is a target DU as described in FIGs. 4, 6A-6B, and 8A-8B.
  • the DU generates a portion of the second LTM DU configuration based on the first LTM DU configuration, and generates the rest of the second LTM DU configuration independent of the first LTM DU configuration.
  • the first LTM DU configuration includes at least one first RS resource configuration.
  • the first LTM DU configuration includes at least one first RS resource configuration and at least one first report configuration for reporting measurement results of some RSs configured in the first RS resource configuration(s).
  • the DU generates at least one second RS resource configuration based on the first RS resource configuration(s) and incudes the second RS resource configuration(s) in the second LTM DU configuration.
  • the DU generates at least one second report configuration for reporting measurement results of some RSs configured in the second RS resource configuration(s) and includes the second report configuration(s) in the second LTM DU configuration.
  • the DU generates at least one second report configuration for reporting measurement results of some RSs configured in the first RS resource configuration(s) and includes the first RS resource configuration(s) and the second report configuration(s) in the second LTM DU configuration.
  • the DU generates at least one third RS resource configuration and/or at least one third report configuration for reporting measurement results of some RSs configured in the third RS resource configuration(s).
  • RSs configured in the third RS resource configuration(s) are different from RSs configured in the first RS resource configuration(s) and the second RS resource configuration(s).
  • some of the third report configuration(s) are the same as the second report configuration(s).
  • the third report configuration(s) are different from the second report configuration(s).
  • the first LTM DU configuration includes at least one first TCI state configuration.
  • the DU generates at least one second TCI state configuration based on the first TCI state configuration(s) and includes the second TCI state configuration(s) in the second LTM DU configuration.
  • the DU includes the first TCI state configuration(s) in the second LTM DU configuration.
  • the CU generates an RRC message including the second LTM DU configuration, and transmits the RRC message to the UE via the DU, an additional DU, or a BS.
  • the CU receives an RRC response message from the UE via the DU, the additional DU, or the BS, in response.
  • the RRC message and the RRC response message are similar to the RRC reconfiguration message and RRC reconfiguration complete message, respectively, as described in FIGs. 3 to 8B.
  • the DU receives a second CU-to-DU message including a third LTM DU configuration for the UE from the CU, where the third LTM DU configuration configures a third cell for LTM (e.g., events 490, 480, 680, 690, 681, 880, 890, or 881).
  • the DU generates a fourth LTM DU configuration to update the second LTM DU configuration, based on the third LTM DU configuration.
  • the fourth LTM DU configuration still configures the second cell for LTM.
  • the DU generates the fourth DU configuration, based on the third LTM DU configuration, the second LTM DU configuration and the first LTM DU configuration.
  • the DU transmits a second DU-to-CU message including the fourth LTM DU configuration to the CU (e.g., events 490, 480. 680, 690, 681, 880, 890. or 881).
  • the fourth LTM DU configuration augments the second LTM DU configuration.
  • the fourth DU configuration includes (new) configurations that do not exist in the second LTM DU configuration.
  • the fourth DU configuration includes (new) configurations updating (existing) configurations included in the second LTM DU configuration.
  • the third LTM DU configuration includes at least one fourth TCI state configuration.
  • the DU generates at least one fifth TCI state configuration based on the fourth TCI state configuration(s) and includes the fifth TCI state configuration(s) in the fourth LTM DU configuration.
  • the DU includes the fourth TCI state configuration(s) in the fourth LTM DU configuration.
  • the (first or second) CU-to-DU message and the (first or second) DU-to-CU message are a UE Context Setup Request message and a UE Context Setup Response message, respectively.
  • the (first or second) CU-to-DU message and the (first or second) DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Response message, respectively.
  • the (first or second) DU-to-CU message is a UE Context Modification Required message.
  • FIG. 17 illustrates an example method 1700, which may be implemented by a CU (e.g., the CU 172 of the first BS 104 or second BS 106), for enabling LTM for a UE (e g., the UE 102).
  • a CU e.g., the CU 172 of the first BS 104 or second BS 106
  • LTM LTM for a UE
  • the method 1700 begins with the CU communicating 1702 with the UE via a serving DU (e.g., events 402, 602, or 802).
  • the CU transmits 1704 a first CU-to-DU message including a first LTM DU configuration for the UE to the serving DU (e.g., events 490, 690, or 890).
  • the CU receives 1706 a first DU-to-CU message including a serving DU configuration from the serving DU (e.g., events 490, 690, or 890).
  • the CU transmits 1708 the serving DU configuration to the UE via the serving DU or a RAN node (e.g.. events 494, 694.
  • the RAN node is another DU (e g., a M- DU or a S-DU in FIGs. 6A, 6B, 8A or 8B) or a BS (e.g., a MN or a SN).
  • another DU e g., a M- DU or a S-DU in FIGs. 6A, 6B, 8A or 8B
  • a BS e.g., a MN or a SN
  • the serving DU and the CU are the DU and the CU of FIG. 15, respectively. Examples and embodiments described for FIG. 15 apply to FIG. 17.
  • FIG. 18 illustrates an example method 1800, which may be implemented by a CU (e.g., the CU 172 of the first BS 104 or second BS 106), for enabling LTM for a UE (e.g., the UE 102).
  • the method 1800 begins with the CU communicating 1802 with the UE via a first DU (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, or 881).
  • a first DU e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, or 881).
  • the CU transmits 1804 a first CU-to-DU message including a first LTM DU configuration for the UE, to a second DU (e.g., events 308, 390, 380. 490, 480. 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • the CU receives 1806 a first DU-to-CU message including a second LTM DU configuration from the second DU (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).
  • the CU transmits 1808 the second LTM DU configuration to the UE via the first DU or a RAN node (e.g.. events 316. 318, 394, 380. 494, 480. 580, 594. 581. 582, 680. 694, 617. 619, 780, 794. 880, 881, 894, 817, or 819).
  • the RAN node is another DU (e.g., the M- DU or S-DU in FIGs. 6A, 6B, 8A, and 8B) or a BS (e.g., a MN or a SN).
  • the first DU is a serving DU (e.g., the DU 174 in FIG. 3, the S-DU in FIG. 4, the M-DU or S-DU in FIGs. 5A-8B).
  • the second DU is a target DU (e.g., the T-DU in FIGs. 4. 6A, 6B, 8A, and 8B).
  • the second DU and the first DU are the same DU (i.e., a serving DU such as the DU 174 in FIG. 3, the S-DU in FIG. 4, or the M-DU or S-DU in FIGs. 5A-8B).
  • the CU and the second DU are the CU and the DU in FIG. 16, respectively. Examples and embodiments described for FIG. 16 apply to FIG. 18.
  • the serving DU is the serving DU described in FIG. 15. Examples and embodiments described for FIG. 15 apply to FIG. 17.
  • the “LTM command” may be replaced by “serving cell change command”, “Layer 1/Layer 2 switching command”, “lower layer switching command” or “lower layer serving cell change command”. In some embodiments, “some” means “one or more”. In some embodiments, “at least one” means “one or more”. In some embodiments, the “DU configuration” may be replaced by “cell group configuration”. In some embodiments, the “cell index” may be replaced with “serving cell index”, “LTM cell index”, “special cell (SpCell) index”, “PCell index”, or “PSCell index”. In some embodiments, the ‘'serving” may be replaced by “source”. In some embodiments, the “measurement report” may be replaced by “measurement result(s)”.
  • a user device in which the techniques of this disclosure may be implemented may be any suitable device capable of w ireless communications such as a smartphone, a tablet computer, a laptop computer, a mobile gaming console, a point-of-sale (POS) terminal, a health monitoring device, a drone, a camera, a media-streaming dongle or another personal media device, a wearable device such as a smartwatch, a wireless hotspot, a femtocell, or a broadband router.
  • the user device in some cases may be embedded in an electronic system such as the head unit of a vehicle or an advanced driver assistance system (ADAS).
  • ADAS advanced driver assistance system
  • the user device may operate as an intemet-of-things (loT) device or a mobile-internet device (MID).
  • the user device may include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.
  • a phrase referring to “at least one of’ or “one or more of’ a list of items refers to any combination of those items, including single members.
  • “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c.
  • Modules may be software modules (e.g., code, or machine- readable instructions stored on non-transitory machine-readable medium) or hardware modules.
  • a hardware module is a tangible unit capable of performing certain operations and may be configured or arranged in a certain manner.
  • a hardware module may comprise dedicated circuitry or logic that is permanently configured (e.g., as a special-purpose processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.) to perform certain operations.
  • FPGA field programmable gate array
  • ASIC application-specific integrated circuit
  • DSP digital signal processor
  • a hardware module may also comprise programmable logic or circuitry (e.g., as encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations.
  • programmable logic or circuitry e.g., as encompassed within a general-purpose processor or other programmable processor
  • the decision to implement a hardware module in dedicated and permanently configured circuitry. or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.
  • the techniques may be provided as part of the operating system, a library used by multiple applications, a particular software application, etc.
  • the software may be executed by one or more general-purpose processors or one or more special-purpose processors.

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne des procédés et des appareils fonctionnant dans un réseau d'accès radio pour faciliter un changement rapide de cellule de desserte à l'aide d'une procédure de mobilité déclenchée par couche inférieure, LTM, réduisant la latence et le surdébit par rapport à une procédure de commutation de cellule déclenchée par L3. L'exécution de la procédure LTM est déclenchée par un rapport de mesure L1. Les entités distribuées d'une station de base échangent des informations (1204) pour préparer un UE à passer d'une cellule de desserte actuelle à une autre cellule pour utiliser une procédure LTM et transmettent (1210) une configuration LTM générée (1206) dans l'une des entités distribuées à l'UE. En outre, une ou plusieurs configurations d'état d'indicateur de configuration de transmission (TCI) peuvent être générées (1208) et transmises (1210) entre les diverses entités distribuées et l'UE.
PCT/US2024/032991 2023-06-15 2024-06-07 Procédés et appareils pour configurer des paramètres pour une mobilité déclenchée par une couche inférieure à l'aide d'indicateurs de configuration de transmission Pending WO2024258739A1 (fr)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022234540A1 (fr) * 2021-05-06 2022-11-10 Telefonaktiebolaget Lm Ericsson (Publ) Impacts d'interface et d'architecture de mobilité centrée l1/l2

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
WO2022234540A1 (fr) * 2021-05-06 2022-11-10 Telefonaktiebolaget Lm Ericsson (Publ) Impacts d'interface et d'architecture de mobilité centrée l1/l2

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HUAWEI: "(TP for L1L2Mob BLCR for TS 38.401): F1 signalling impact on the incoming LSs for LTM", vol. RAN WG3, no. Incheon, KR; 20230522 - 20230526, 21 May 2023 (2023-05-21), XP052395033, Retrieved from the Internet <URL:https://ftp.3gpp.org/Meetings_3GPP_SYNC/RAN3/Docs/R3-232824.zip R3-232824.docx> [retrieved on 20230521] *
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