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WO2025117217A1 - Mobilité déclenchée par couche inférieure avec informations d'accès aléatoire sans contention - Google Patents

Mobilité déclenchée par couche inférieure avec informations d'accès aléatoire sans contention Download PDF

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Publication number
WO2025117217A1
WO2025117217A1 PCT/US2024/056193 US2024056193W WO2025117217A1 WO 2025117217 A1 WO2025117217 A1 WO 2025117217A1 US 2024056193 W US2024056193 W US 2024056193W WO 2025117217 A1 WO2025117217 A1 WO 2025117217A1
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Prior art keywords
ltm
configuration
cell
procedure
message
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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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Classifications

    • 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
    • H04W36/0077—Transmission or use of information for re-establishing the radio link of access information of target access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0833—Random access procedures, e.g. with 4-step access
    • H04W74/0838—Random access procedures, e.g. with 4-step access using contention-free random access [CFRA]
    • 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

Definitions

  • This document describes methods and apparatuses operating in wireless communication systems such as (but not limited to) the ones described in 3rd Generation Partnership Project (3GPP) technical specifications (TSs), for example, Long Term Evolution (LTE), or Fifth Generation (5G), or future 6G communication systems.
  • 3GPP 3rd Generation Partnership Project
  • TSs Technical specifications
  • LTE Long Term Evolution
  • 5G Fifth Generation
  • This document relates to wireless communications and, more particularly, to managing a cell switch using contention-free random access (CFRA) resources information, when the cell switch is a lower-layer triggered mobility (LTM) cell switch.
  • CFRA contention-free random access
  • 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 3 rd Generation Partnership Project (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 known as a user equipment (UE), to a base station (BS)) as well as in the downlink direction (from the BS to the UE).
  • 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 Radio Resource Control
  • the UE and a 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.
  • SRBs to exchange RRC messages as well as non-access stratum (NAS) messages
  • NAS non-access stratum
  • UEs may use several types of SRBs and DRBs.
  • DC dual connectivity
  • the cells associated with the BS operating the master node (MN) define a master cell group (MCG)
  • MCG master cell group
  • SN secondary node
  • SCG secondary cell group
  • So-called SRB1 resources carry RRC messages, which in some cases include NAS messages over the dedicated control channel (DCCH)
  • DCCH dedicated control channel
  • 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, which may be referred to as MCG SRBs.
  • SRB3 resources allow the UE and the SN to exchange RRC messages related to the SN and may be referred to as SCG SRBs.
  • Split SRBs allow the UE to exchange RRC messages directly with the MN via lower layer resources of the MN and the SN.
  • DRBs using the lower-layer resources of only the MN may be referred as MCG DRBs
  • DRBs using the lower-layer resources of only the SN may be referred as SCG DRBs
  • DRBs using the lower-layer resources of both the MCG and the SCG may be referred to as split DRBs.
  • the UE in some scenarios may concurrently utilize resources of multiple radio access network (RAN) nodes (e.g., BSs or components of a distributed BS), interconnected by a backhaul.
  • RAN radio access network
  • RATs radio access technologies
  • this type of connectivity is referred to as Multi-Radio Dual Connectivity (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.
  • the RAN configures the UE to transmit layer 3 (L3) measurement results. Based on L3 measurement results received from the UE, the RAN transmits a RRC reconfiguration message configuring Reconfiguration with Synchronization (e.g., the RRC reconfiguration message includes a ReconfigurationWithSync IE) for change of the serving cell (e.g., PCell or PSCell).
  • L3 layer 3
  • the RRC reconfiguration message includes a ReconfigurationWithSync IE for change of the serving cell (e.g., PCell or PSCell).
  • the RAN In cases where the UE operates in carrier aggregation (CA) of at least one secondary cell (SCell) with the PCell or PSCell, the RAN has to release the at least one SCell due to the change of the PCell or PSCell.
  • the serving cell change involves complete L2 (and L1) resets, leading to longer latency, larger overhead and longer interruption time.
  • LTM lower-layer triggered mobility
  • the RAN While the RAN communicates with the UE via the serving cell, the RAN receives one or more layer 3 (e.g., RRC) measurement results from the UE. Based on the layer 3 (L3) measurement result(s), the RAN determines to configure an LTM candidate cell for LTM cell switch. To configure the LTM candidate cell for the UE, the RAN transmits an LTM configuration to the UE, via RRC signaling, to configure the LTM candidate cell. In some embodiments, the RAN includes the configuration parameters for the first radio bearer in the LTM configuration. Later on, the RAN receives one or more layer 1 (L1) measurement results from the UE.
  • L3 layer 3
  • L3 layer 3
  • L3 layer 3
  • L3 layer 3
  • L3 layer 3
  • L3 layer 3
  • the RAN determines to configure an LTM candidate cell for LTM cell switch.
  • the RAN transmits an LTM configuration to the UE, via RRC signaling, to configure the LTM candidate cell.
  • the RAN includes
  • the RAN determines that the LTM candidate cell qualifies to be a serving cell for the UE. Therefore, the RAN transmits an LTM cell switch command to the UE to command the UE to perform the LTM cell switch to the LTM candidate cell.
  • the UE performs a cell change from the serving cell to the LTM candidate cell, in response to the LTM cell switch command.
  • the UE disconnects from the serving cell and performs a random access (RA) procedure on the LTM candidate cell with the RAN.
  • RA random access
  • the LTM cell switch command is a MAC control element (CE) as specified in the revised 3GPP TS 38.321.
  • the RAN may include CFRA resources information in the LTM cell switch command.
  • the CFRA resources information includes contention-free Random Access Resources (i.e., configuration parameters) for the UE to perform the LTM cell switch to an LTM candidate cell. With the CFRA resources information, the UE should be able to perform a CFRA procedure on the LTM candidate cell to complete the LTM cell switch.
  • the UE In response to the LTM cell switch command, the UE performs a MAC reset to reset a MAC entity that the UE uses to communicate with the RAN.
  • the UE is configured to discard the contention-free Random Access Resources in the MAC reset.
  • the UE only performs a contention-based random access (CBRA) procedure on the LTM candidate cell with the RAN, which increases latency to complete the LTM cell switch.
  • CBRA contention-based random access
  • an LTM command may include contention-free random access (CFRA) resources information so that the cell switching latency is further reduced by using a CFRA procedure.
  • CFRA contention-free random access
  • the UE retains the CFRA resources information to be used for an RA procedure related to LTM cell switch.
  • the UE is configured to retain the CFRA resources information when performing the MAC reset if the MAC reset precedes an LTM-related RA procedure.
  • a decision of the UE in retaining the CFRS resources information may be triggered by receiving an LTM command that includes the CFRA resources information.
  • the order of performing the RA procedure and the MAC reset is set, so that the RA procedure is performed first. For this approach, the MAC reset discards the CFRA resources information.
  • a different event than the LTM command triggers the initiation of the RA procedure. Such event may be an uplink protocol data unit (PDU), or a MAC procedure, or a physical downlink control channel (PDCCH) order.
  • PDU uplink protocol data unit
  • PDCH physical downlink control channel
  • FIG. 1 is a block diagram of an example system in which a radio access network and a user device may implement the techniques of this document for managing an RA procedure for an LTM cell switch;
  • FIG. 2 is a block diagram of an example BS including a central unit (CU) and a distributed unit (DU) that may operate in the system of FIG. 1 ;
  • CU central unit
  • DU distributed unit
  • FIG. 3 illustrates a first scenario for a UE and a network entity (NE) operating according to an embodiment based on an LTM command.
  • FIG. 4 illustrates a second scenario for a UE and an NE operating according to another embodiment based on an LTM command and plural Dlls.
  • FIGs. 5A and 5B illustrate third scenarios for UEs and NEs operating according to other embodiments based on an LTM command and plural BSs.
  • FIGs. 6A and 6B illustrate fourth scenarios for UEs and NEs operating according to yet other embodiments based on an LTM command, plural BSs, and plural DUs in one BS.
  • FIGs. 7A and 7B illustrate fifth scenarios for UEs and NEs operating according to some embodiments based on an LTM command and main and secondary DUs in the BS.
  • FIGs. 8A and 8B illustrate sixth scenarios for UEs and NEs operating according to some other embodiments based on an LTM command and plural DUs in the BS.
  • FIGs. 9A and 9B depict flow diagrams illustrating methods performed by the UE according to various embodiments in which an LTM command includes CFRA resources information.
  • FIGs. 10A to 10C depict flow diagrams illustrating methods performed by the UE according to various embodiments in which an LTM command includes CFRA resources information and an RA procedure is triggered by various events.
  • FIGs. 11 A to 11 D depict flow diagrams illustrating methods performed by various layers of the UE according to various embodiments in which an LTM command includes CFRA resources information.
  • FIG. 12 depicts a flow diagram illustrating a method performed by the UE for determining whether to retain or discard CFRA resources information.
  • FIGs. 13A and 13B depict flow diagrams illustrating methods performed by the UE for determining to initiate or refrain from performing an RA procedure.
  • FIG. 14 depicts a flow diagram illustrating a method performed by the UE for continuing an RA procedure despite a MAC reset, when the RA procedure is for LTM cell switch.
  • Methods and apparatuses described in this section embody techniques related to performing an LTM cell switch by using an LTM command that includes CFRA resource information so that the cell switching latency is further reduced by using a CFRA procedure.
  • FIG. 1 depicts an example wireless communication system 100 in which communication devices may implement these techniques.
  • the wireless communication system 100 includes a UE 102, a first BS 104, a second BS 106, and a core network (CN) 110.
  • FIG. 1 shows the NE 107 being either the RAN 105 or any component of the RAN, for example, the first BS 104 or the second BS 106.
  • 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 for the UE 102, respectively.
  • 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 first BS 104 is an MeNB and the second BS 106 is a SgNB
  • the UE 102 may be in EUTRA-NR DC (EN-DC) with the MeNB and the SgNB.
  • EN-DC EUTRA-NR DC
  • 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 next generation 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 ) for example prior to the handover.
  • a core network (CN) 110 may be an evolved packet core (EPC) 111 or a fifth-generation core (5GC) 160, both of which are depicted in FIG. 1.
  • EPC evolved packet core
  • 5GC fifth-generation core
  • the first BS 104 may be an eNB supporting an S1 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.
  • 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 Protocol 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.
  • UPF User Plane Function
  • AMF Access and Mobility Management
  • SMF Session Management Function
  • 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 124A
  • 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. 1).
  • the cells 124A, 124B, and 124C may partially overlap, so that the UE 102 may communicate in carrier aggregation (CA) with the first BS 104.
  • CA carrier aggregation
  • the first BS 104 may operate the cells 124A, 124B, and 124C via one or more transmit and receive points (TRPs). More particularly, when the 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 ELITRA cells. Although the examples below refer specifically to specific CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general the techniques of this document 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.
  • 6G sixth generation
  • the first BS 104 is equipped with processing hardware 130 that may include one or more general-purpose processors (e.g., CPUs) 132 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 may further include a transceiver 134 for communicating with the UE 102.
  • general-purpose processors e.g., CPUs
  • the processing hardware 130 may include special-purpose processing units.
  • the processing hardware may further include a transceiver 134 for communicating with the UE 102.
  • the processing hardware 130 may include a PHY controller 136 configured to transmit data and control signal on physical downlink (DL) channels and DL reference signals with one or more user devices (e.g., UE 102) via one or more cells (e.g., the cell(s) 124A, 124B and/or 124C) and/or one or more TRPs.
  • the PHY controller 136 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., the cell(s) 124A, 124B and/or 124C) and/or one or more TRPs.
  • DL physical downlink
  • UL physical uplink
  • the processing hardware 130 may further include a MAC controller or entity 138 configured to perform MAC functions with one or more user devices.
  • the MAC functions include a random access (RA) procedure, managing UL timing advance (TA) for the one or more user devices, and/or communicating UL/DL MAC PDUs with the one or more user devices.
  • the MAC functions include lower triggered mobility (LTM) related functions as described below.
  • the processing hardware 130 may further include an RRC controller 136 to implement procedures and messaging at the RRC sublayer of the protocol communication stack.
  • the RRC controller 139 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, 146, 148, and 149 may be similar to the components 132, 134, 136, 138, and 139, respectively.
  • the UE 102 is equipped with processing hardware 150, which may include one or more general-purpose processors 152, such as CPUs, and non-transitory computer-readable memory 152 storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units.
  • the processing hardware 150 may also include a transceiver 152 for communicating with the BSs.
  • the PHY controller 156 is configured to receive data and control signal on physical DL channels and/or DL reference signals with the BS 104 or 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 156 is also configured to transmit data and control signal on physical UL channels and/or UL reference signals with the BS 104 or 106 via one or more cells (e.g., the cell(s) 124A, 124B, 124C and/or 126) and/or one or more TRPs.
  • the processing hardware 150 in an example embodiment includes a MAC controller 158 configured to perform MAC functions with BS 104 or 106.
  • the MAC functions include an RA procedure, managing UL timing advance for the one or more user devices, and communicating UL/DL MAC PDUs with the BSs 104 or 106.
  • the MAC functions include LTM related functions as described below.
  • the processing hardware 150 may further include an RRC controller 160 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 the MN 104 or the SN 106.
  • the UE 102 may apply one or more security keys when communicating on the radio bearer, in the uplink (UL) (from the UE 102 to a BS) and/or downlink (from a BS to the UE 102) direction.
  • a radio bearer e.g., a DRB or an SRB
  • the UE 102 may apply one or more security keys when communicating on the radio bearer, in the uplink (UL) (from the UE 102 to a BS) and/or downlink (from a BS to the UE 102) direction.
  • FIG. 2 depicts an example distributed embodiment of a BS such as the BS 104 or 106.
  • the BS 170 in this embodiment may include a central 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 the processing hardware 130.
  • the CU 172 is equipped with the processing hardware 140.
  • the processing hardware 140 in an example embodiment includes an SN RRC controller 142 configured to manage or control one or more RRC configurations and/or RRC procedures when the 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 in an example embodiment includes MAC controller configured to manage or control one or more MAC operations or procedures (e.g., the RA 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.
  • the process hardware may include further a physical layer controller configured to manage or control one or more physical layer operations or procedures.
  • FIGs. 3 to 8B that are similar, are labeled with similar reference numbers (e.g., event 316 is similar to event 416 of FIGs. 4A and 4B, event 516 of FIG. 5A, 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. 7B), with differences discussed below where appropriate.
  • event 316 is similar to event 416 of FIGs. 4A and 4B, event 516 of FIG. 5A, 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. 7B
  • event 316 is similar to event 416 of FIGs. 5A, 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. 7B
  • the first BS 104 includes a CU 172 and a DU 174 and the DU 174 operates the cell 124A.
  • the UE 102 initially communicates 302 with the DU 174 on the cell 124A using a serving DU configuration, and communicates with the CU 172 via the DU 174, e.g., using a serving CU configuration.
  • the DU 174 is a serving DU that is communicating with the UE 102.
  • the UE 102 in carrier aggregation (CA) communicates with the DU 174 on the cell 124A and other cell(s) (e.g., cell 124D not shown in FIG.
  • CA carrier aggregation
  • the DU 174 operates the other cell(s).
  • the cell 124A and/or the other cell(s) are serving cell(s) for the UE 102.
  • the UE 102 communicates with the DU 174 on the cell 124A only.
  • the UE 102 communicates with the DU 174 on the cell 124A and/or other cell(s) via one or multiple TRPs.
  • the 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 124A 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 serving DU configuration includes at least one first non-LTM TCI state configuration for the serving cell(s).
  • the DU 174 may transmit these configuration parameters and/or the first non-LTM TCI state configuration(s) to the CU 172.
  • the CU 172 generates one or more messages (e.g., RRC reconfiguration message(s)) including the configuration parameters and/or the first non-LTM TCI state configuration(s) and transmits the one or more messages to the UE 102 via the DU 174.
  • the DU 174 transmits the configuration parameters and/or the first non-LTM TCI state configuration(s) to the UE 102 directly.
  • the serving DU configuration is CellGroupConfig IE defined in 3GPP TS 38.331.
  • the serving DU configuration includes configuration parameters in the CellGroupConfig IE.
  • the serving CU configuration includes PDCP configuration parameters, measurement configuration parameters, and/or radio bearer configuration parameters.
  • the serving CU configuration includes a MeasConfig 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 (CSI) measurement and reporting.
  • the serving CU configuration includes a CSI-MeasConfig IE or configuration parameters for CSI measurement and reporting.
  • the 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 and DU 174 communicate with each other using the first non-LTM TCI state configuration(s), e.g., in the events 302, 318, 320, 324, 325, 330, and/or 331.
  • the DU 174 transmits at least one first non-LTM TCI States Activation/Deactivation command to the UE 102 to activate some of the first non-LTM TCI state configuration(s).
  • the UE 102 activates some of the first non-LTM TCI state configuration(s) in response to the first non-LTM TCI States Activation/Deactivation command(s).
  • the DU 174 indicates deactivation of some of the first non-LTM TCI state configuration(s) in some of the first non-LTM TCI States Activation/Deactivation command(s).
  • the UE 102 and DU 174 communicate with each other using the activated non-LTM TCI state configuration(s), e.g., events 302, 318, 320, 324, 325, 330, and/or 331.
  • each of the first non-LTM TCI States Activation/Deactivation command(s) is a MAC CE.
  • the MAC CE(s) may include one or more TCI States Activation/Deactivation for UE-specific PDSCH MAC CEs, one or more TCI State Indication for UE-specific PDCCH MAC CEs, one or more PUCCH spatial relation Activation/Deactivation MAC CEs, one or more Enhanced TCI States Activation/Deactivation for UE-specific PDSCH MAC CEs, one or more Enhanced PUCCH Spatial Relation Activation/Deactivation MAC CEs, one or more Enhanced TCI States Indication for UE-specific PDCCH MAC CEs, one or more PUCCH spatial relation Activation/Deactivation for multiple TRP PUCCH repetition MAC CEs, and/or one or more Unified TCI States Activation/Deactivation MAC CEs.
  • the DU 174 includes a serving cell ID (e.g., a serving cell index) in each of the first non-LTM TCI States Activation/Deactivation command(s) to identify the first non-LTM TCI state configuration(s).
  • a serving cell ID e.g., a serving cell index
  • Each of the serving cell ID(s) indicates a respective serving cell of the serving cell(s).
  • the serving DU configuration includes the serving cell ID(s) and configures association(s) between the serving cell ID(s) and the first non-LTM TCI state configuration(s).
  • the UE 102 While communicating with the first BS 104, the UE 102 transmits 304 at least one measurement report to the DU 174.
  • the at least one measurement report includes layer 1 (L1) 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 F1 application protocol (F1AP) message(s) (e.g., UL RRC Message Transfer message(s)).
  • F1AP F1 application protocol
  • the DU 174 does not transmit or refrains from transmitting the L1 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., RRCReconfiguration 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 I E(s)) and/or L1 measurement configuration(s).
  • the L1 measurement configuration(s) e.g., CSI-MeasConfig I E(s)
  • the L1 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 L1 measurement results.
  • the reference signal(s) includes CSI-RS(s) and/or Synchronization Signal (SS)/ Physical Broadcast Channel (PBCH) Resource Block(s) (SSB(s)).
  • the L1 measurement resource configuration(s) is/are CSI-ResourceConfig IE(s).
  • the L1 measurement reporting configuration(s) configures way(s) the LIE 102 uses to transmit L1 measurement results/reports.
  • the L1 measurement report configuration(s) is/are CSI-ReportConfig IE(s).
  • the UE 102 transmits the L3 measurement report(s) to the CU 172 via the DU 174 in accordance with the L3 measurement configuration(s).
  • the UE 102 transmits the L1 measurement report(s) to the DU 174 in accordance with the L1 measurement configuration(s) or L1 measurement reporting configuration(s). In one embodiments, the DU 174 does not transmit the L1 measurement report(s) to the CU 172.
  • the L1 measurement configuration(s) are new RRC I E(s) defined in 3GPP TS 38.331 for a lower layer triggered mobility (LTM).
  • the L1 measurement resource configuration(s) are new RRC IE(s) defined in 3GPP TS 38.331 for the LTM.
  • the L1 measurement reporting configuration(s) are new RRC I E(s) defined in 3GPP TS 38.331 for the LTM.
  • each of the L1 measurement reporting configuration(s) may include a trigger event configuration configuring a trigger event to trigger the UE 102 to transmit a L1 measurement report. If the UE 102 detects the trigger event, the UE 102 transmits a L1 measurement report to the DU 174.
  • each of the L1 measurement report(s) may include at least one L1 measurement result.
  • the at least L1 measurement result includes at least one L1 -reference signal received power (L1- RSRP) value and/or at least one L1 -Signal to Interference Noise Ratio (L1-SINR) value.
  • L1- RSRP L1 -reference signal received power
  • L1-SINR L1 -Signal to Interference Noise Ratio
  • the UE 102 transmits a PUSCH transmission including the L1 measurement report to the DU 174. That is, the UE 102 transmits the each of the L1 measurement report(s) on a PUSCH to the DU 174. In yet other embodiments, the UE 102 transmits a portion of the L1 measurement report(s) on PUCCH(s) and the rest of the L1 measurement report(s) on physical UL shared channel(s) (PUSCH(s)) to the DU 174.
  • each of the L1 measurement report(s) is a part of CSI (i.e. , a CSI component) or CSI.
  • 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 SSB Resource Indicator (SSBRI), a Layer Indicator (LI), and/or a Rank Indicator (Rl).
  • CQI channel quality indicator
  • PMI Precoding Matrix Indicator
  • CRI CSI-RS Resource Indicator
  • SSBRI SSB Resource Indicator
  • LI Layer Indicator
  • Rl Rank Indicator
  • the UE 102 does not transmit the L1 measurement report(s) in format of 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 a RRC message (e.g., MeasurementReport message).
  • each of the L3 measurement configuration(s) includes a particular measurement identity (e.g., measld) and each of the L3 measurement report(s) includes a particular measurement identity in a particular L3 measurement configuration.
  • the CU 172 may determine that the L3 measurement report is associated to a L3 measurement configuration identified by the measurement identity.
  • the UE 102 transmits a MAC control element (CE) including the measurement report to the DU 174 in the event 304.
  • a MAC control element CE
  • the UE 102 generate 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 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.
  • the UE 102 obtains the at least one L1 measurement result and/or at least one L3 measurement result from the measurements.
  • the DU 174 transmits 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) for LTM for the UE 102.
  • the first BS 104 prepares 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.
  • 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. In some embodiments, if the L3 measurement report(s) indicates that signal strength and/or quality of the first cell is above a first predetermined threshold, is better than strength and/or quality of the cell 124A, and/or is better than strength and/or quality of the cell 124A by a first predetermined threshold, the CU 172 determines to prepare the first cell for the UE 102.
  • the DU 174 determines to prepare the first cell for the UE 102.
  • 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) 1 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 cell ID 1 is cell global identity (CGI).
  • the cell ID is a portion of the CGI.
  • the cell ID is a physical cell ID (PCI).
  • the CU 172 includes an LTM indicator in the first CU-to-DU message to indicate the DU 174 to prepare the first cell for LTM.
  • the LTM indicator is the LTM Information to be Setup IE or LTM Information to be Modified IE.
  • the CU 172 includes the LTM indicator in an LTM Information to be Setup IE and includes the LTM Information to be Setup IE in the first CU-to-DU message.
  • the CU 172 includes the LTM indicator in an LTM Information to be Modified IE and includes the LTM Information to be Modified IE in the first CU-to-DU message.
  • the DU 174 In response to the first CU-to-DU message, the DU 174 generates a first LTM DU configuration (referred to herein after 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.
  • 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 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., non-reference 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.
  • the DU 174 generates the LTM DU configuration(s) 1 , and/or 2, ..., N which are delta configuration(s) to augment the reference LTM DU configuration.
  • 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 CellGroupConfig 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 channel state information (CSI) measurement and/or reporting.
  • CSI channel state information
  • 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 RRCReconfiguration 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 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 if 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. Otherwise, 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 1) in the RRC reconfiguration message of the events 316 and 318. In such cases, the CU 172 generates the first container.
  • the first container is to indicate the UE 102 not to apply the LTM DU configuration 1 and/or the LTM CU configuration 1 immediately.
  • the UE 102 receives an RRC reconfiguration message (e.g., the RRC reconfiguration message of the event 318) including a configuration (e.g., the LTM DU configuration 1).
  • the UE 102 refrains from immediately applying the configuration. Otherwise, if the configuration is not included in the first container, the UE 102 may apply the configuration immediately.
  • the first container includes or is a first addition or modification list (e.g., Itm-CandidateToAddModList field or LTM- CandidateToAddModList 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.
  • the CU 172 generates an RRC message (e.g., RRCRecconfiguration message) including the LTM DU configuration 1 and/or the LTM CU configuration 1 , and includes the RRC message in the element 1.
  • element 1 is an addition or modification IE (e.g., LTM-ConfigToAddMod IE, LTM-Candidate IE, LTM- CandidateToAddMod IE or LTM-CandidateConfigToAddMod IE).
  • the UE 102 may store the first addition or modification list, e.g., in a variable in its random access memory (RAM).
  • the DU 174 generates the first container and includes the first container in the first DU-to-CU message. In yet other alternative embodiments, the DU 174 generates element 1 and includes the 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.
  • 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 the 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 encrypted 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 decrypts the encrypted RRC reconfiguration and encrypted 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 an 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 an LTM command activating the LTM DU configuration 1 as described for events 330, 350.
  • the events 308 (optional) and 310 are collectively referred to in FIG. 3 as an LTM preparation procedure 390.
  • the events 316, 318, 320, and 322 are collectively referred to in FIG. 3 as an LTM configuration delivery procedure 394.
  • the first CU-to-DU message is a UE Context Setup Request message
  • the first DU-to-CU message is a UE Context Setup Response message
  • 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 second DU-to-CU message is a UL RRC Message Transfer message.
  • the second DU-to-CU message is a 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., nonreference 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 and/or the cell ID 1.
  • the CU 172 includes the ID 1 in the first CU-to-DU message.
  • the CU 172 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 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 third DU-to-CU message is a UE Context Modification Required message. In such cases, the CU 172 transmits a UE Context Modification Confirm message to the DU 174 in response to the UE Context Modification Required message.
  • the events 312 (optional) and/or 314 (optional) are collectively referred to in FIG. 3 as an LTM ID assignment procedure 392.
  • the DU 174 may include the ID 1 in the LTM DU configuration 1 , first container or element 1. Alternatively, the 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.
  • the DU 174 includes the reference LTM DU configuration in the first container.
  • the 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.
  • the 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.
  • 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 IE), MAC layer configuration parameters (e.g., MAC-CellGroupConfig IE) and/or RLC configuration parameters (e.g., RLC-BearerConfig I E(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 a MeasConfig 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 L1 measurement configuration 1 (e.g., a CSI-MeasConfig IE) and/or at least one configuration indicator (TCI) state configuration.
  • the LTM CU configuration 1 includes the L1 measurement configuration and/or the TCI state configuration(s) 1.
  • the L1 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 a 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 the 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 .
  • 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 the cell 1 .
  • the DU 174 includes the L1 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 Modification Required message.
  • the CU 172 includes the serving DU configuration 1 in the RRC reconfiguration message 316, 318. In other embodiments, 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 an RA configuration in the LTM DU configuration 1. In other embodiments, the DU 174 does not include an RA 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 RA configuration in the LTM DU configuration 1. Otherwise, if the cell 124A and first cell are synchronized, the DU 174 determines to not include the RA 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 RA configuration in the LTM DU configuration 1.
  • the DU 174 determines to not include the RA configuration in the LTM DU configuration 1. If the LTM DU configuration 1 includes the RA configuration, the UE 102 performs the RA procedure in the event 332 in accordance with the RA configuration, as described below, based on the CERA resources information. Otherwise, if the LTM DU configuration 1 does not include the RA configuration or indicates the UE 102 to skip an RA procedure in LTM, the UE 102 skips or refrains from performing the RA procedure of the event 332 in response to the LTM DU configuration 1 excluding the RA configuration.
  • the DU 174 includes RA 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.
  • the UE 102 performs the RA procedure in the event 332 in accordance with the RA configuration parameters, as described below.
  • the RA configuration parameters configure physical random access channel (PRACH) resources, an association between SSB and PRACH resources, and/or one or more PRACH occasions.
  • PRACH physical random access channel
  • the DU 174 determines to include, in the LTM DU configuration 1 , a first indication configuring the UE 102 not to perform an RA procedure on the first cell. Otherwise, if the 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 RA 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 RA procedure in accordance with the RA 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., ReconfigurationWithSync 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., ReconfigurationWithSync IE) in the LTM DU configuration 1 or special cell configuration. In some embodiments, the DU 174 includes an LTM cell switch information in the first LTM DU configuration 1. In some embodiments, the DU 174 includes the RA configuration (parameters) in the LTM cell switch information (e.g., Itm-Cell Switch I nfo field or LTM-Cell Switch Info IE).
  • RA configuration parameters
  • the DU 174 determines to include the reconfiguration with sync configuration in the LTM DU configuration 1 if the cell 124A and first cell are not synchronized. Otherwise, if the 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. 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 reconfiguration with sync configuration in the LTM DU configuration 1.
  • 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 RA procedure in the event 332 as described below, in response to or in accordance with the reconfiguration with sync configuration. Otherwise, if the LTM DU configuration 1 does not include the reconfiguration with sync configuration, the UE 102 skips or refrains from performing the RA procedure of the event 332. In some embodiments, the DU 174 includes a cell ID (i.e. , cell ID 1) of cell 1 (i.e.
  • the cell ID 1 may be a PCI. In another embodiment, the cell ID 1 is a CGI. In some embodiments, the cell ID 1 included in the LTM DU configuration 1 is a PCI, while the cell ID 1 included in the first CU-to- DU message is a CGI. In some further embodiments, the LTM DU configuration 1 includes a cell index 1 indexing the cell ID 1 or the first cell. The cell index 1 is not a cell ID. The cell index takes fewer bits than the cell ID. In some embodiments, 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 a 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 and includes the LTM DU configuration(s) 2, ...
  • N in DU-to-CU message(s) 2, ... , N, respectively, as described 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 maximum number of “N” is 4, 8, 16 or 32. Examples and embodiments of the LTM DU configuration 1 may apply to the LTM DU configuration(s) 2, ... , N.
  • the CU 172 and DU 174 performs 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, ...
  • 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 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, ... , N in the first container.
  • the CU 172 may include the lD(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. In other embodiments, the CU 172 receives the ID(s) 2, ... , N from the DU 174 in the first DU-to-CU message of the procedure 390. In yet other embodiments, 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, ... , N, respectively.
  • 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, ..., N and the LTM DU configuration(s) 2, N, respectively.
  • 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. Thus, the third CU-to-DU message may be omitted. In yet other embodiments, 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, ... , N. In one embodiment, the DU 174 includes the ID(s) 2, ..., N in the LTM DU configuration(s) 2, ..., N. Thus, 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, ... , N in the LTM DU configuration(s) 2, ..., N.
  • 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 .
  • 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, similar to the events 316 and 318.
  • the 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- ConfigToAdd Mod List IE, Itm-CandidateConfigToAddModList field, or LTM- CandidateConfigToAddModList IE), and each of the element(s) 2, ... , N may be an addition or modification IE (e.g., Itm-ConfigToAddMod field, LTM-ConfigToAddMod IE, Itm-CandidateConfigToAddMod field, or LTM-CandidateConfigToAddMod IE).
  • Itm-ConfigToAddModList field e.g., LTM-ConfigToAdd Mod List IE, Itm-CandidateConfigToAddModList field, or LTM- CandidateConfigToAddModList IE
  • each of the element(s) 2, ... , N may be an addition or modification IE (e.g., Itm-ConfigToAddMod field, LTM-ConfigToAddMod
  • the UE 102 may store the second addition or modification list together with the first addition or modification list, e.g., in a variable in its random access memory (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 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 L1 measurement configuration(s).
  • each of the LTM DU configuration(s) 1 , ... , N may be a CellGroupConfig 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 I E(s)).
  • the LTM DU configuration(s) 1 , ... , N are CellGroupConfig IE(s) defined in 3GPP TS 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. [0089] In some embodiments, 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). 1 ⁇ M ⁇ N.
  • the CU 172 transmits an RRC reconfiguration message to the UE 102 via the DU 174 to indicate the UE 102 to release the LTM DU configuration M or element M.
  • 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.
  • the UE 102 releases the LTM DU configuration M or element M and transmits a 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 indicate 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.
  • the DU 174 determines to release the LTM DU configuration K. In response to the determination, the DU 174 transmits a DU-to-CU message to the CU 172 to release the LTM DU configuration K. To indicate the LTM DU configuration K is released, 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. 1 ⁇ K ⁇ N.
  • a release indication e.g., a field or IE
  • 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 a 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 may transmit 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 the event 318 or transmitting the RRC reconfiguration complete message in the 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. In other embodiments, 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 include L1 measurement report(s) or L3 measurement repot(s), as described 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.
  • 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.
  • the UE 102 does not transmit the L1 measurement report(s) in format of RRC message(s) to the DU 174.
  • the UE 102 transmits 324 the at least one measurement report to the 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 the 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 L1 measurement result and/or at least one L3 measurement result from the measurements and includes the at least one L1 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., MeasConfig I E(s)), as described for the event 304.
  • the at least one measurement configuration includes or is L1 measurement configuration(s), as described above.
  • the L1 measurement configuration(s) may be CSI-MeasConfig IE(s) defined in 3GPP TS 38.331.
  • the L1 measurement configuration(s) may include RS resource configuration(s) and/or report configuration(s).
  • the UE 102 transmits 324 the L1 measurement report(s) on UL resources (e.g., PUCCH resources or PLISCH resources) to the DU 174 in accordance with the report configuration(s).
  • the DU 174 receives the L1 measurement report(s) on the UL resources in accordance with the report configuration(s).
  • the report configuration(s) are or are similar to CSI-ReportConfig 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 L1 measurement result(s).
  • the L1 measurement report(s) is/are CSI report(s). In other embodiments, the L1 measurement report(s) is/are MAC CE(s). In some embodiments, 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 L1-RSRP values and/or one or more L1-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(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-ResourceConfig I E(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).
  • the 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 L1 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 3GPP TS 38.281.
  • the DU 174 After (e.g., in response to) receiving the measurement report(s) 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 the UE 102.
  • the LTM command may include instructions for the UE to perform a cell switch and/or CERA resources information.
  • the DU 174 transmits the first LTM command on the cell 124A to the UE 102.
  • 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.
  • the UE 102 determines (e.g., identifies) the LTM DU configuration 1 or element 1 , based on the 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.
  • the 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 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.
  • 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 includes cell ID 1 in the first LTM command, where the cell ID 1 identifies the cell 1.
  • the cell ID 1 included in the first LTM command is the same as the cell ID 1 included in the first CU-to-DU message.
  • the DU 174 determines the cell ID 1 (e.g., PCI) included in the first LTM command from the cell ID 1 (e.g., CGI) received in the first CU-to-DU message.
  • the UE 102 determines (e.g., identifies) the LTM DU configuration 1 or element 1 , based on the cell ID 1 .
  • the UE 102 Before receiving the first LTM command, 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. In other words, the UE 102 decodes the LTM DU configuration 1 or element 1 to obtain the cell ID 1 , before receiving the first LTM command. Thus, 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 . Before receiving the first LTM command, the UE 102 retrieves the cell ID(es) 2, ...
  • the DU 174 has a mapping table to store mappings between the PCI(s) 1 , ..., N and the CGI(s) 1 , ..., N for the cell(s) 1 , ... , N, respectively.
  • 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.
  • the UE 102 may determine the cell index 1 , the ID 1 , LTM DU configuration 1 , or element 1 in accordance with the bit 1 set to the first value in the bit map.
  • bit 0, ... , N-1 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-1) 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., L1 measurement report(s) or new-type measurement report(s)) of the event 324 includes at least one measurement result for the first cell, 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).
  • the 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, the 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 L1-RSRP value(s), L1-RSRQ value(s) and/or L1-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 the UE 102.
  • the DU 174 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 for the UE 102.
  • the at least one measurement report (e.g., L3 measurement report(s)) of the events 324 and 326 includes at least one measurement result for the first cell.
  • the CU 172 determines to activate the LTM DU configuration 1 or transmit the first LTM command, because the at least one measurement result indicates that signal strength or quality of the first cell is above a second predetermined threshold.
  • the second predetermined threshold is different from the first predetermined threshold.
  • the second predetermined threshold is larger than the first predetermined threshold.
  • the at least one measurement report of the event 326 indicates that signal strength or quality of the first cell is suitable for communication with the UE 102.
  • the second predetermined threshold is equal to the first predetermined threshold.
  • 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 the 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 includes the cell index 1 in the fourth CU-to-DU message.
  • the DU 174 transmits 330 the first LTM command to the UE 102 and optionally transmits a fourth DU-to-CU message to the CU 172.
  • the CU 172 includes the cell index 1 in the fourth CU-to-DU message.
  • the DU 174 may determine to activate the LTM DU configuration 1 in accordance with the cell index 1.
  • the CU 172 may include the cell ID 1 in the fourth CU-to-DU message.
  • the DU 174 determines to activate the LTM DU configuration 1 in accordance with the cell ID 1.
  • the CU 172 may include the ID 1 in the fourth Cll-to- Dll message.
  • the 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., F1 application protocol (F1AP) messages defined in 3GPP TS 38.473.
  • F1AP F1 application protocol
  • the DU 174 might transmit 329 to the CU 172 a DU-to-CU message indicating LTM (being) executed.
  • the DU-to-CU message is an LTM Cell Change Notification message.
  • 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 3GPP 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 cyclic redundancy check (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 the event 330.
  • CRC cyclic redundancy check
  • a format of the DCI may be an existing DCI format defined in a 3GPP TS (e.g., 3GPP TS 38.212).
  • the format of the DCI may be a new DCI format defined in a 3GPP TS (e.g., 3GPP TS 38.212).
  • the DU 174 does not perform security protection (e.g., integrity protection and/or encryption) 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 encryption
  • 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.
  • the CU 172 may transmit a first RRC reconfiguration message including the L3 measurement configuration (e.g., a MeasConfig IE) to the UE 102 before the event 306.
  • the DU 174 transmits 330 the first LTM command in response to the L1 measurement report(s) 324 for the first cell.
  • the CU 172 may transmit a second RRC reconfiguration message including the L1 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 the event 316.
  • the second RRC reconfiguration message is different from the RRC reconfiguration message of the event 316.
  • the UE 102 accesses 332 the first cell.
  • the 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 an RA procedure on the first cell with the DU 174, in response to receiving the first LTM command. In other embodiments, the UE 102 skips an RA procedure and transmits the first transmission (e.g., a RUSCH 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 RUSCH transmission or a PUCCH transmission
  • the DU 174 configures the access of the UE 102 to the first cell, including whether or not the UE 102 performs an RA procedure, in the LTM DU configuration 1.
  • the UE 102 determines whether to perform an RA 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 an RA procedure, the UE 102 performs an RA procedure on the first cell in the 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 an RA procedure when the UE 102 receives an LTM command for the first cell.
  • the DU 174 configures the UE 102 to skip the RA procedure for an LTM serving cell change to the first cell.
  • the UE 102 after receiving the first LTM command, the UE 102 skips the RA procedure and transmits the first transmission (e.g., a RUSCH transmission or a PUCCH transmission) on the first cell to the DU 174 in the event 332.
  • the DU 174 excludes a reconfiguration with sync configuration in the LTM DU configuration 1 to configure the UE 102 skipping an RA procedure for an LTM serving cell change to the first cell.
  • the LTM DU configuration 1 includes the reconfiguration with sync configuration or the RA configuration.
  • the DU 174 configures whether the UE 102 performs an RA procedure on the first cell in an LTM command.
  • the UE 102 determines whether to perform the RA procedure on the first cell in the 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 an RA procedure.
  • the UE 102 In response to the indication or the first LTM command including the indication, the UE 102 skips an RA procedure and directly transmits the first transmission (e.g., a RUSCH transmission or a PUCCH transmission) on the first cell to access the first cell.
  • the DU 174 excludes the indication in the first LTM command to configure the UE 102 to perform an RA procedure.
  • the UE 102 performs an RA procedure on the first cell to access the first cell.
  • the DU 174 includes a timing advance value in the first LTM command to indicate skipping an RA 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 an RA 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 an RA procedure.
  • the UE 102 performs an RA procedure on the first cell to access the first cell.
  • the RA procedure is a four-step RA procedure. In other embodiments, the RA procedure is a two-step RA procedure. In some embodiments, the RA procedure is a CFRA procedure. In other embodiments, the RA procedure is a contention-based RA procedure. In cases where the RA procedure is a four-step RA procedure, the UE 102 transmits a Message 3 including a UE identity to the DU 174 via the first cell in the RA 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
  • the UE 102 transmits a Message A including the UE identity to the DU 174 via the first cell in the RA procedure.
  • the DU 174 transmits a contention resolution message (e.g., Message B) to the UE 102 in response to the Message A.
  • the UE 102 determines that the UE 102 successfully completes the RA 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 DU 174 includes the second C-RNTI in the reconfiguration with sync configuration. In other embodiments, the DU 174 includes the second C-RNTI in the LTM cell switch information.
  • the RA procedure is a contention free RA 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 RA procedure (i.e., the UE 102 successfully accesses the first cell).
  • the DU 174 configures the UE 102 to perform an RA 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 RA procedure. If the DU 174 configures the UE 102 to skip an RA 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 a 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 (e.g., LTM TCI state configuration) for the first cell 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 or includes 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 DL RS(s) include SSB(s) and/or tracking reference signal(s) (TRS(s)).
  • the CU 172 receives a DU-to-CU message including the first TCI state configuration(s) from the DU 174 and transmits 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-to-CU message is the DU-to-CU message 310 or the DU-to- CU message 314.
  • the DU-to-CU message is a message different from the messages 310, 314.
  • the DU-to-CU message is a UE Context Modification Response message or a UE Context Modification Required message.
  • the DU 174 includes the LTM DU configuration 1 in a first interface protocol I E/field in the DU-to-CU message 310, and includes the serving DU configuration in a second interface protocol I E/field in the DU-to-CU message 314.
  • the events 312 (optional) and/or 314 (optional) are collectively referred to in FIG. 3 as an LTM TCI state configuration procedure 392.
  • the 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 some embodiments, the CU 172 includes the LTM ID 1 and the first LTM TCI state configuration(s) in an element for LTM, an addition or modification list for LTM, or a container, and the CU 172 includes the element, addition or modification list for LTM, or the container in the RRC message, similar to the element 1 , the first addition or modification list, or the first container respectively. In some embodiments, the RRC message is the RRC reconfiguration message 316, 318.
  • the CU 172 may include the first LTM TCI state configuration(s) in the element 1.
  • the RRC reconfiguration is another RRC reconfiguration message (not shown in FIG. 3).
  • 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 I E/field is a first F1AP I E/field and the second interface protocol I E/field is a second F1AP lE/field.
  • one of the first F1AP I E/field and the second F1AP I E/field is a F1AP CellGroupConfig I E/field and the other is not the F1 AP CellGroupConfig I E/field.
  • the DU 174 includes the first F1AP I E/field in a DU to CU RRC Information IE in the message 314 and includes the second F1AP I E/field in the DU to CU RRC Information IE in the DU-to-CU message.
  • neither the first F1AP lE/field nor the second F1AP IE is a F1AP CellGroupConfig lE/field.
  • the second F1AP I E/field is the DU to CU RRC Information IE and the first F1AP I E/field is a new IE specific for including an LTM DU configuration.
  • the DU 174 transmits 325 at least one first LTM TCI states Activation/Deactivation command to the UE 102 to activate some of the first LTM TCI state configuration(s).
  • the UE 102 activates some of the first LTM TCI state configuration(s) in response to the first LTM TCI States Activation/Deactivation command(s).
  • the DU 174 indicates deactivation of some of the first LTM TCI state configuration(s) in some of the first LTM TCI States Activation/Deactivation command(s).
  • the DU 174 transmits one or more DL RSs on the candidate cell(s) using the activated LTM TCI state configuration(s) or the first LTM TCI state configuration(s).
  • the DL RS(s) may include one or more SSBs and/or one or more TRSs.
  • the UE 102 receives the DL RS(s) using the activated LTM TCI state configuration(s).
  • the UE 102 may obtain L1 measurement results from the received DL RS(s) and transmits the L1 measurement results to the DU 174.
  • the UE 102 may obtain L3 measurement results from the received DL RS(s) and transmits the L3 measurement results to the CU 172 via the DU 174.
  • the DU 174 refrains from using the first LTM TCI state configuration(s) to communicate with the UE 102 on the serving cell(s). In some embodiments, the UE 102 refrains from using the first LTM TCI state configuration(s) to communicate with the DU 174 on the serving cell(s).
  • each of the first LTM TCI States Activation/Deactivation command(s) is a MAC CE (e.g., Candidate Cell TCI States Activation/Deactivation command).
  • the DU 174 includes the LTM ID 1 in each of the first LTM TCI States Activation/Deactivation command(s) to identify the first LTM TCI state configuration(s).
  • the DU 174 includes a candidate cell index (e.g., the cell index 1) in each of the first LTM TCI States Activation/Deactivation command(s) to identify the first LTM TCI state configuration(s). In such cases, the candidate cell index is different from the LTM ID 1.
  • each of the first LTM TCI state configuration(s) may include the candidate cell index.
  • the CU 172 includes the candidate cell index in the RRC message including the first LTM TCI state configuration(s).
  • the CU 172 includes the candidate cell index in the element 1.
  • the UE 102 and the DU 174 determine the candidate cell index from the PCI of the first cell. In such cases, the first BS 104 does not transmit the candidate cell index to the UE 102.
  • the UE 102 after (e.g., in response to) receiving the first LTM command or accessing 332 the first cell, the UE 102 performs DL reception (e.g., monitors one or more PDCCHs) or UL transmission on the first cell using some or all of the first LTM TCI state configuration(s) in the event 336. In other embodiments, after (e.g., in response to) receiving the first LTM command or accessing 332 the first cell, the UE 102 performs DL reception (e.g., monitors one or more PDCCHs) or UL transmission on the first cell without using the first LTM TCI state configuration(s) in the event 336.
  • DL reception e.g., monitors one or more PDCCHs
  • UL transmission on the first cell without using the first LTM TCI state configuration(s) in the event 336.
  • each of the first LTM TCI state configuration(s) includes a TCI state ID identifying the corresponding TCI state configuration.
  • the first LTM TCI state configuration(s) includes LTM TCI state configuration(s) 1 , ..., L, where L is a positive integer larger than zero.
  • the LTM TCI state configuration(s) 1 , ... , L include TCI state ID(s) 1 , .... L identifying the LTM TCI state configuration(s) 1 , ... , L, respectively.
  • the DU 174 includes the TCI state ID 1 in the first LTM command to indicate to the UE 102 to activate the LTM TCI state configuration 1 to communicate on the first cell.
  • the UE 102 activates the LTM TCI state configuration 1 in response to receiving the TCI state ID 1 in the first LTM command.
  • the UE 102 accesses 332 on the first cell using the (activated) LTM TCI state configuration 1 .
  • the UE 102 accesses 332 on the first cell without using the first LTM TCI state configuration(s).
  • the UE 102 communicates 336 on the first cell using the (activated) LTM TCI state configuration 1.
  • the DU 174 communicates 336 with the UE 102 on the first cell, using the activated LTM TCI state configurations 1.
  • the UE 102 monitors one or more PDCCHs, receives one or more DL RSs, receives one or more PDSCH transmissions, and/or transmits the first transmission and/or one or more additional transmissions, using the LTM TCI state configuration 1.
  • the DU 174 detects 332 that the UE 102 accesses the first cell and/or communicates 336 with the UE 102 on the first cell, based on the LTM TCI state configuration 1.
  • the DU 174 receives 332 the first transmission and/or 336 the additional transmission(s) from the UE 102 on the first cell, based on the TCI state configuration 1.
  • the DU 174 transmits one or more PDCCHs, one or more PDSCH transmissions, and/or one or more DL RSs, based on the LTM 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 activate the TCI state configuration 2 to communicate on the first cell, in addition to the TCI state ID 1.
  • the UE 102 activates the LTM TCI state configuration 1 in response to receiving the TCI state ID 1 in the first LTM command, and activates the LTM TCI state configuration 2 in response to receiving the TCI state ID 2 in the first LTM command.
  • the UE 102 accesses 332 and/or communicates 336 on the first cell using the activated LTM TCI state configurations 1 and 2.
  • the DU 174 communicates with the UE 102 on the first cell in the events 332 and/or 336, using the activated LTM TCI state configurations 1 and 2.
  • the UE 102 after applying one or more TCI state configurations (e.g., the TCI state configuration(s) 1 and/or 2) indicated in an LTM command (e.g., the first LTM command), the UE 102 takes time (e.g., beam application time or cell switch delay) to acquire TCI state(s) configured in the TCI state configuration(s) (e.g., synchronize and/or receive DL RS(s) configured in the TCI state configuration(s)).
  • the time to acquire TCI state(s) is considered as a switch delay.
  • the DU 174 takes the switch delay into account when communicating with the UE 102 on the first cell in the events 332 and/or 336.
  • the DU 174 starts to communicate with the UE 102 on the first cell in the events 332 and/or 336 after the switch delay, using the activated LTM TCI state configuration(s) 1 and/or 2.
  • the UE 102 monitors one or more PDCCHs, receives one or more DL RSs, and/or receives one or more PDSCH transmissions from the DU 174 on the first cell using the LTM TCI state configuration 1 and transmits the first transmission and/or one or more additional transmissions on the first cell to the DU 174 using the LTM TCI state configuration 2.
  • the DU 174 transmits one or more control signals one or more PDCCHs, one or more DL RSs, and/or one or more PDSCH transmissions to the UE 102 on the first cell using the LTM TCI state configuration 1 and receives the first transmission and/or one or more additional transmissions on the first cell from the UE 102 using the LTM TCI state configuration 2.
  • Each of the control signal(s) includes a DCI and a scrambled CRC for the DCI.
  • the UE 102 monitors one or more PDCCHs from the DU 174 on the first cell using the LTM TCI state configuration 1 and receives one or more PDSCH transmissions from the DU 174 on the first cell using the LTM TCI state configuration 2.
  • Each of the control signal(s) includes a DCI and a scrambled CRC for the DCI.
  • the DU 174 transmits one or more control signals on one or more PDCCHs on the first cell to the UE 102 using the LTM TCI state configuration 1 and transmits one or more PDSCH transmissions to the UE 102 on the first cell using the LTM TCI state configuration 2.
  • the UE 102 transmits the first transmission and/or one or more additional transmissions to the DU 174 on the first cell, using the LTM TCI state configuration 1.
  • the DU 174 receives the first transmission and/or one or more additional transmissions from the UE 102 on the first cell, using the LTM TCI state configuration 1.
  • the UE 102 may transmit the first transmission and/or one or more additional transmissions to the DU 174 on the first cell, using the LTM TCI state configuration 2.
  • the DU 174 receives the first transmission and/or one or more additional transmissions from the UE 102 on the first cell, using the LTM 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 and/or one or more additional transmissions on the first cell using one of the TCI state configuration 1 and the TCI state configuration 2.
  • the DU 174 transmits one or more control signals on one or more PDCCHs receives the first transmission and/or one or more additional transmissions from the UE 102 on the first cell, using the LTM TCI state configuration 2.
  • Each of the control signal(s) includes a DCI and a scrambled CRC for the DCI.
  • the CU 172 receives a CN-to-BS message including a UE capability IE of the UE 102 from a CN (e.g., the CN 110 or the AMF 164), e.g., during the event 302.
  • the CN-to-BS message is a NG application protocol (NGAP) message.
  • the CU 172 receives a BS-to-BS message including the UE capability IE from another BS (e.g., the BS 106), e.g., before the event 302.
  • the CU 172 receives a UE Capability Information message including the UE capability IE from the UE 102, via the DU 174 or another DU e.g., during the event 302.
  • the DU 174 receives the UE capability IE (e.g., UE-NR-Capability or UE-6G-Capability) of the UE 102 from the CU 172, e.g., during the event 302.
  • the UE capability IE indicates that the UE 102 supports RACH-less LTM.
  • the DU 174 configures and/or activates one or more LTM TCI state configurations for the UE 102 as described above.
  • the DU 174 refrains from configuring and/or activating an LTM TCI state configuration for the UE 102.
  • the DU 174 refrains from including an LTM TCI state configuration for the UE 102 in the DU-to-CU message(s) described above.
  • the CU 712 does not transmit an LTM TCI state configuration to the UE 102.
  • the CU 172 does not include an LTM TCI state configuration in the RRC reconfiguration message 316, 318.
  • the UE capability IE indicates that the UE supports early timing advance (TA) acquisition. Based on the indication of supporting early TA acquisition, the DU 174 configures and/or activates one or more LTM TCI state configurations for the UE 102 as described above. In some embodiments, if the UE capability IE indicates that the UE 102 does not support the early TA acquisition, the DU 174 refrains from configuring and/or activating an LTM TCI state configuration for the UE 102. For example, the DU 174 refrains from including an LTM TCI state configuration for the UE 102 in the DU-to-CU message(s) described above. Accordingly, the 011 712 does not transmit an LTM TCI state configuration to the UE 102. For example, the CU 172 does not include an LTM TCI state configuration in the RRC reconfiguration message 316, 318.
  • TA timing advance
  • the UE capability IE indicates that the UE supports a UE-based TA acquisition (e.g., the UE acquires UL synchronization based on reference signal time difference (RSTD) measurements). Based on the indication of supporting the UE-based TA acquisition, the DU 174 configures and/or activates one or more LTM TCI state configurations for the UE 102 as described above. In some embodiments, if the UE capability IE indicates that the UE 102 does not support the UE-based TA acquisition, the DU 174 refrains from configuring and/or activating an LTM TCI state configurations for the UE 102.
  • RSTD reference signal time difference
  • the DU 174 refrains from including an LTM TCI state configuration for the UE 102 in the DU-to-CU message(s) described above. Accordingly, the CU 712 does not transmit an LTM TCI state configuration to the UE 102. For example, the CU 172 does not include an LTM TCI state configuration in the RRC reconfiguration message 316, 318.
  • the UE capability IE indicates that the UE supports LTM TCI states. Based on the indication of supporting LTM TCI states, the DU 174 configures and/or activates one or more LTM TCI state configurations for the UE 102 as described above. In some embodiments, if the UE capability IE indicates that the UE 102 does not support LTM TCI states, the DU 174 refrains from configuring and/or activating an LTM TCI state configuration for the UE 102. For example, the DU 174 refrains from including an LTM TCI state configuration for the UE 102 in the DU-to-CU message(s) described above. Accordingly, the CU 712 does not transmit an LTM TCI state configuration to the UE 102. For example, the CU 172 does not include an LTM TCI state configuration in the RRC reconfiguration message 316, 318.
  • the DU 174 does not determine whether to provide an LTM TCI state configuration for the UE 102.
  • the DU 174 provides the LTM TCI state configuration(s) for the UE 102 to the CU 172 as described above.
  • the CU 172 determines whether to transmit the first LTM TCI state configuration(s) to the UE 102.
  • the CU 172 transmits the first LTM TCI state configuration(s) to the UE 102 as described above.
  • the CU 172 refrains from transmitting an LTM TCI state configuration to the UE 102. For example, the CU 172 refrains from transmitting the first LTM TCI state configuration(s) to the UE 102. For example, the CU 172 refrains from including the first LTM TCI state configuration(s) in the RRC reconfiguration message 316, 318.
  • the CU 172 transmits the first LTM TCI state configuration(s) to the UE 102 as described above. In some embodiments, if the UE capability IE indicates that the UE 102 does not support the early TA acquisition, the CU 172 refrains from transmitting an LTM TCI state configuration to the UE 102. For example, the CU 172 refrains from transmitting the first LTM TCI state configuration(s) to the UE 102. For example, the CU 172 refrains from including the first LTM TCI state configuration(s) in the RRC reconfiguration message 316, 318.
  • the CU 172 transmits the first LTM TCI state configuration(s) to the UE 102 as described above. In some embodiments, if the UE capability IE indicates that the UE 102 does not support the UE-based TA acquisition, the CU 172 refrains from transmitting an LTM TCI state configuration to the UE 102. For example, the CU 172 refrains from transmitting the first LTM TCI state configuration(s) to the UE 102. For example, the CU 172 refrains from including the first LTM TCI state configuration(s) in the RRC reconfiguration message 316, 318.
  • the CU 172 transmits the first LTM TCI state configuration(s) to the UE 102 as described above. In some embodiments, if the UE capability IE indicates that the UE 102 does not support LTM TCI states, the CU 172 refrains from transmitting an LTM TCI state configuration to the UE 102. For example, the CU 172 refrains from transmitting the first LTM TCI state configuration(s) to the UE 102. For example, the CU 172 refrains from including the first LTM TCI state configuration(s) in the RRC reconfiguration message 316, 318.
  • the DU 174 may not activate or may determine to not activate a (LTM) TCI state configuration in the first LTM command. In such cases, the DU 174 does not include a TCI state ID in the first LTM command. Thus, when the UE 102 receives the first LTM command not including a TCI state configuration, the UE 102 refrains from using the first LTM TCI configuration(s) to access and/or communicate on the first cell.
  • LTM LTM
  • the DU 174 does not include or refrains from including a TCI state ID in the first LTM command. Otherwise, if the UE capability IE indicates that the UE 102 supports the RACH-less LTM, the DU 174 includes the one or more TCI state IDs (e.g., the TCI state ID 1 and/or the TCI state ID 2) in the first LTM command as described above.
  • the TCI state IDs e.g., the TCI state ID 1 and/or the TCI state ID 2
  • the DU 174 if the DU 174 does not configure LTM TCI state configurations for the first cell for the UE 102, the DU 174 does not include or refrains from including a TCI state ID in the first LTM command. Otherwise, if the DU 174 configures one or more LTM TCI state configurations (e.g., the first LTM TCI state configuration(s)), the DU 174 includes one or more LTM TCI state IDs (e.g., the TCI state ID 1 and/or the TCI state ID 2) in the first LTM command.
  • LTM TCI state configurations e.g., the first LTM TCI state configuration(s)
  • the DU 174 includes one or more LTM TCI state IDs (e.g., the TCI state ID 1 and/or the TCI state ID 2) in the first LTM command.
  • the DU 174 does not include or refrains from including a TCI state ID in the first LTM command. Otherwise, if the UE capability indicates that the UE 102 supports the early TA acquisition, the DU 174 includes the TCI state ID 1 and/or the TCI state ID 2 in the first LTM command as described above.
  • the DU 174 does not include or refrains from including a TCI state ID in the first LTM command. Otherwise, if the UE capability indicates that the UE 102 supports the early TA acquisition, the DU 174 includes the TCI state ID 1 and/or the TCI state ID 2 in the first LTM command as described above.
  • the DU 174 does not include or refrains from including a TCI state ID in the first LTM command. Otherwise, if the UE capability indicates that the UE 102 supports LTM TCI states, the DU 174 includes the TCI state ID 1 and/or the TCI state ID 2 in the first LTM command as described above. In some embodiments, the UE 102 stops using or deactivates the first non-LTM TCI configuration(s) upon receiving the first LTM command.
  • the UE 102 After successfully accessing the first 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
  • 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, the 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 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 In case that the UE 102 receives the LTM CU configuration 1 and 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 and (at least a portion of) the reference LTM CU configuration not augmented by 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 and (at least a portion of) the reference LTM CU configuration not augmented by the LTM CU configuration 1 .
  • the UE 102 In 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 communicates 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 to 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 (e.g., 3GPP TS 38.331).
  • 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.
  • 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.
  • the CU 172 indicates that the reference LTM CU configuration is a delta configuration to augment to 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 case that the UE 102 neither receives the reference LTM CU configuration and 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 DU 174 includes or configures at least one second non-LTM TCI state configuration for the first cell in the LTM DU configuration 1. While communicating with the UE 102 at event 332 or 336, the DU 174 may transmit a second non-LTM TCI States Activation/Deactivation command on the first cell to the UE 102 to activate the second non-LTM TCI state configuration(s) and/or deactivate the activated LTM TCI state configuration(s).
  • the DU 174 includes a serving cell index for the first cell in the second non-LTM TCI States Activation/Deactivation command.
  • the DU 174 includes the serving cell index in the LTM DU configuration 1.
  • the UE 102 stops using or deactivates the (activated) LTM TCI state configuration(s) in response to receiving the second non-LTM TCI States Activation/Deactivation command.
  • the second non-LTM TCI States Activation/Deactivation command(s) is a MAC CE.
  • the MAC CE may be a TCI States Activation/Deactivation for UE- specific PDSCH MAC CE, a TCI State Indication for UE-specific PDCCH MAC CEs, a PUCCH spatial relation Activation/Deactivation MAC CEs, an Enhanced TCI States Activation/Deactivation for UE-specific PDSCH MAC CE, an Enhanced PUCCH Spatial Relation Activation/Deactivation MAC CE, an Enhanced TCI States Indication for UE-specific PDCCH MAC CE, an PUCCH spatial relation Activation/Deactivation for multiple TRP PUCCH repetition MAC CE, or an Unified TCI States Activation/Deactivation MAC CE.
  • the second non-LTM state configuration(s) may be Rel-15/16 TCI state configuration(s) (i.e., not a unified joint/DL/UL TCI state). This imply that the first BS 104 may configure Rel-15/16 beam indication framework for the first cell.
  • Non- LTM TCI state configurations activated/indicated by the second non-LTM TCI States Activation/Deactivation command(s) may be only applicable to a channel or RS (PDSCH/PDCCH/CSI-RS/PUCCH/SRS).
  • the UE 102 if the UE 102 receives a second non-LTM TCI States Activation/Deactivation command, the UE would stop or use the first LTM TCI state for channels or RSs, which are applicable to share/follow/apply unified TCI states. For example, if the UE 102 receives an Enhanced TCI States Indication for UE-specific PDCCH MAC CE, the UE 102 would stop or use the first LTM TCI state for at least one of other channels or RSs applicable to share/follow/apply unified TCI states as well (e.g., PDSCH, PUSCH, PUCCH, CSI-RS or SRS). If the UE 102 receives a second non- LTM TCI States Activation/Deactivation command, the UE 102 may deactivate the activated first LTM TCI state configuration(s).
  • the second non-LTM TCI state configuration(s) includes at least one TCI state configured in the first LTM TCI state configuration(s). In other embodiments, TCI state(s) in the second non-LTM TCI state configuration(s) is/are different from the TCI(s) in the first LTM TCI state configuration(s). In some embodiments, the second non-LTM TCI state configuration(s) configure more TCI states than the first LTM TCI state configurations(s). In some other embodiments, TCI state(s) in the second non-LTM TCI state configuration(s) is/are identical with the TCI(s) in the first LTM TCI state configuration(s). The first BS 104/CU 172/DU 174 may notify the UE 102 in a RRC message or signal, whether first LTM TCI state configuration(s) is identical or different or a subset of the second non-LTM TCI state configuration(s).
  • the first LTM TCI state configuration(s) for the first cell is a subset of the second non-LTM TCI state configuration(s) for the first cell.
  • TCI state IDs of the first LTM TCI state configuration(s) for the first cell are not overlapped or identical with those of the second non-LTM TCI state configuration(s) for the first cell.
  • TCI state IDs of the first LTM TCI state configuration(s) for the first cell ranges from #000 to #007; TCI state IDs of the second non-LTM TCI state configurations for the first cell ranges from #008 to #015.
  • the UE 102 activates the first LTM TCI state configuration identified by TCI state ID #001 ; if the second non-LTM TCI States Activation/Deactivation command indicates TCI state ID #012, the UE 102 activates the second non-LTM TCI state configuration identified by TCI state ID #012.
  • the UE 102 combines or catenate the first LTM TCI state configuration(s) for the first cell and the second non-LTM TCI state configurations for the first cell for non-LTM TCI state activation/indicate purpose.
  • the UE 102 considers or determines the first LTM TCI state configuration(s) for the first cell as the non-LTM TCI state configurations for the first cell.
  • the DU 174 may not include or configure the at least one second non-LTM TCI state configuration for the first cell in the LTM DU configuration 1.
  • the UE 102 considers or determines the at least one first TCI state configuration(s) (e.g., LTM TCI state configuration) for the first cell as the non-LTM TCI state configurations for the first cell.
  • the UE 102 when the UE 102 receives the second non-LTM TCI States Activation/Deactivation command(s), the UE 102 considers/determines that the TCI state ID(s) indicated in the second non-LTM TCI States Activation/Deactivation command(s) refer to the first LTM TCI state configuration(s) for the first cell. For example, if the second non-LTM TCI States Activation/Deactivation command indicates TCI state ID #000, the UE 102 activates and/or applies the first TCI state configuration (e.g., LTM TCI state configuration) identified by TCI state ID #000, and performs non-LTM communication in the first cell.
  • the first TCI state configuration e.g., LTM TCI state configuration
  • a first LTM TCI state configuration associates or includes a SSB corresponding to QCL type A
  • the UE 102 refrains from using such TCI state configuration for non-LTM purpose or communication in the first cell.
  • the UE 102 may consider or determine a first LTM TCI state configuration(s) for the first cell as a non-LTM TCI state configurations for the first cell, unless it includes or associates a SSB corresponding to QCL type A.
  • the DU 174 when orwhile the DU 174 communicates 332, 336 with the UE 102 on the first cell, the DU 174 refrains from transmitting an LTM TCI States Activation/Deactivation command to the UE 102 to activate an LTM TCI state configuration for the first cell or associated with the LTM ID 1 .
  • the DU 174 transmits a second LTM TCI States Activation/Deactivation command to the UE 102 to activate at least one LTM TCI state configuration in the first LTM TCI state configuration(s) that is/are not activated by the first LTM command.
  • the UE 102 activates the LTM TCI state configuration(s) indicated in the second LTM TCI States Activation/Deactivation command.
  • the second LTM TCI States Activation/Deactivation command In the second LTM TCI States
  • the DU 174 may deactivate the LTM TCI state configuration(s) activated in the first LTM command, in some embodiments.
  • the UE 102 deactivate the LTM TCI state configuration(s) activated in the first LTM command, in response.
  • the UE 102 and the DU 174 communicate with each other on the first cell using the LTM TCI state configuration(s) activated by the second LTM TCI States Activation/Deactivation command, as described above.
  • the UE 102 transmits a RRC message (e.g., RRC reconfiguration complete message) to the CU 172 via the DU 174 and the first cell to indicate that the UE 102 applies the LTM DU configuration 1 .
  • a 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 RA procedure.
  • the UE 102 includes the RRC message in a RUSCH 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, a Long Term Evolution (LTE) Positioning Protocol (LPP) PDU, a RRC PDU and/or a NAS PDU.
  • LTE Long Term Evolution
  • LPP Long Term Evolution
  • the RRC PDU includes a UL-DCCH-Message excluding a RRC reconfiguration complete message.
  • the NAS PDU includes a Mobility 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.
  • the CU 172 determines that the UE 102 connects to the first cell upon receiving the DU-to-CU message of the 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 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.
  • the CU 172 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. In other embodiments, 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 the 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 indicating 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 indicate 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 indicating that the LTM DU configuration(s) 1 and/or 2, ... , N is/are full configuration(s).
  • the CU 172 may include, in the additional RRC reconfiguration message, a single indication indicating that the LTM DU configuration(s) 2, ..., N is/are full configuration(s).
  • the CU 172 may include, in the first container, a single indication indicating 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 configuration(s) 2, N, the CU 172 may include, in the first container, a particular indication indicating 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 indicating 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 indicating that the LTM DU configuration 1 is a full configuration.
  • the CU 172 may include an indication indicating 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 configuration(s) based on the indication(s) above.
  • each of the indication(s) above is different from a fullConfig 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.
  • 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 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) indicating 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 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(s).
  • 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, the 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. In such cases, 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 to communicate with a DU MAC entity 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 RA procedure or communicating 336 with the DU 174 via the first cell.
  • the DU 174 resets 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 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) e.g., the event 332
  • 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 RA 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 (i.e., a full UE MAC reset). In the full UE MAC reset, the 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 (i.e., a partial UE MAC reset). In the partial UE MAC reset, the 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:
  • timeAlignmentTimer(s) of the UE 102 • consider timeAlignmentTimer(s) of the UE 102 as expired, if the UE 102 is configured to perform the RA 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:
  • 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, the 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: • consider 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 RA 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 RA 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 RA 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.
  • 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, that 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.
  • the UE 102 may reestablish the first UE RLC entity before performing 332 the RA procedure or communicating 336 with the DU 174 via the first cell.
  • the UE 102 may reestablish the first UE RLC entity while or after performing 332 the RA 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:
  • 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 indicating that the configuration 1 is a full configuration, the UE 102 may reestablish the first UE RLC entity 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.
  • the DU 174 reestablishes a first DU RLC entity 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. In other embodiments, the acknowledgement is a MAC CE. In yet other embodiments, the acknowledgement is a PUCCH transmission. In some embodiments, 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.
  • the UE 102 refrains from reestablishing some or all of the at least one UE RLC entity in response to receiving the first LTM command.
  • the 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.
  • the UE 102 communicates with the DU 174 on the first cell using the 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 RA 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.
  • the UE 102 uses at least one UE PDCP entity (e.g., PDCP 210) to communicate UL PDCP PDUs and/or DL PDCP PDlls with at least one CU PDCP entity (e.g., PDCP 210) of the CU 172 in the 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.
  • the 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.
  • the 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. For example, 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. In some embodiments, 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.
  • the CU 172 may or may not reestablish the first CU PDCP entity. After or in response to performing the PDCP recovery 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 the 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.
  • the 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 the some or all of the at least one UE PDCP entity (not reestablished).
  • the 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 events 338 (optional) and 340 (optional) are collectively referred to in FIG. 3 as a resource release or modification 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 to the UE 102.
  • 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 (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.
  • the descriptions for the 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 124A”, “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.
  • the events 344, 346, 348, 350, 351 , 352, 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, 356 are collectively referred to in FIG. 3 as an 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 a 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 the scenario 400. The differences between the scenarios 300 and 400 are described below.
  • the 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. 3A.
  • the UE 102 transmits 404, 406 at least one measurement report (e.g., L3 measurement report(s)) to the CU 172 via the S-DU 174A. Based on the at least one measurement report, 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-DU 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-Dll message and DU-to-CU message in the 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 a 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+1 , ... , N+M for LTM for the UE 102, similar to the procedure 490.
  • 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.
  • the CU 172 transmits a CU-to-DU message including cell ID(s) N+1 , ...
  • the T-DU 174B transmits a DU-to-DU message including the LTM DU configuration(s) N+1 , ... , N+M to the CU 172.
  • the LTM DU configuration(s) N+1 , ..., N+M configures the cell(s) N+1 , ... , N+M for LTM, respectively.
  • the LTM DU configuration(s) N+1 , ... , N+M include configuration parameters for communication on the cell(s) N+1 , ..., N+M, respectively.
  • the CU 172 then transmits the LTM DU configuration(s) N+1 , ... , N+M in a RRC reconfiguration message in an additional LTM configuration delivery procedure, similar to the LTM configuration delivery procedure 394 or 494.
  • the LTM preparation procedure 490 is a UE Context Setup procedure and the additional LTM preparation procedure is a UE Context Modification procedure.
  • the LTM procedure 490 and the addition LTM preparation procedures are UE Context Setup procedures.
  • the LTM procedure 490 and the addition LTM preparation procedures are UE Context Modification procedures.
  • the CU 172 and S-DU 174A might perform procedure 380 with the UE 102, as described for FIG. 3.
  • procedure 380 the CU 172 and S-DU 174A performs 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 the event 310. In other embodiments, the CU 172 and S-DU 174A do not perform the 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
  • 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.
  • 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 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+1 , ... , 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+1 , ...
  • 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+1 , ..., N+M, considering or based on configuration(s) in the LTM DU configuration(s) of the procedure 380.
  • the LTM DU configuration X of the 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 the 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 I E(s).
  • the T-DU 174B generates at least one report configuration 1 for reporting, on the 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 the 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 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 CSI-RS resource indicators (CRI(s)).
  • the quantized measurement values might include one or more L1-RSRP values and/or one or more L1-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 I E(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 UL resources (e.g., PUCCH resources or RUSCH resources) on the 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 L1-RSRP values and/or one or more L1-SINR values.
  • the T-Dll 174B may generate RS resource configuration(s) 2, .... N, and/or N+1 , N+M and/or report configuration(s) 2, N, and/or N+1 , N+M, considering or based on the RS resource configuration(s) X, and include the RS resource configuration(s) 2, N, and/or N+1 , ...
  • 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 or includes 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-r17 field, one or more TCI-UL-State-r17 lEs, a dl-OrJointTCI- StateToAddModList-r17 field, one or more TCI-State lEs, TCI-ActivatedConfig IE and/or a tci-StatesToAddModList field.
  • the LTM DU configuration X includes a PDSCH-Config IE and the PDSCH-Config 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 an 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-Dll 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+1 , N+M in the LTM DU configuration(s) 2, N, and/or N+1 , ... , N+M, respectively, as described above.
  • 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+1 , ... , N+M identifying the LTM DU configuration(s) N+1 , ... , N+M, respectively, and performs a procedure (similar to the procedure 492) with the T-DU 174B to provide the ID(s) N+1 , ...
  • the T-DU 174B associates the ID(s) N+1 , ... , N+M with the LTM DU configuration(s) N+1 , ... , N+M and/or the cell ID(s) N+1 , ... , N+M, respectively.
  • the T-DU 174B assigns ID(s) N+1 , ... , N+M identifying the LTM DU configuration(s) N+1 , ... , 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 receives 414 a DU-to-CU message from the S-DU 174A in response.
  • 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.
  • the message 412 and message 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 , ..., N in the CU-to-DU message 412. In one embodiment, the CU 172 includes the ID(s) 1 , ... , N in the CU-to-DU message 412. In another embodiment, the CU 172 includes the cell index(es) 1 , ... , N in the CU-to-DU message 412. In some alternative embodiments, the CU 172 may perform multiple LTM ID transfer procedures to transmit the ID(s) 1 , ...
  • the CU 172 includes a particular portion of the ID(s) 1 , ..., N, cell ID(s) 1 , ... , N and/or LTM DU configuration(s) 1 , ..., N in a CU-to-DU message similar to the message 412.
  • the S-DU 174A associates the ID(s) 1 , .... N with the LTM DU configuration(s) 1 , .... N and/or the cell ID(s) 1 , ... , N, respectively.
  • the CU 172 may perform multiple LTM cell index transfer procedures to transmit the cell index(es) 1 , ... , N, cell ID(s) 1 , .... N and/or LTM DU configuration(s) 1 , ... , N to the S-DU 174A.
  • the CU 172 includes a particular portion of the cell index(es) 1 , ..., N, cell ID(s) 1 , ... , N and/or LTM DU configuration(s) 1 , ... , N in a CU-to-DU message similar to the message 412.
  • the S-DU 174A associates the cell index(es) 1 , ... , N with the LTM DU configuration(s) 1 , ... , N and/or the cell ID(s) 1 , ... , N, respectively.
  • the S-DU 174A generates a first serving DU configuration, based on the LTM DU configuration(s) 1 , 2, ... , and/or N, and includes the first serving DU configuration in the DU-to-CU message 414.
  • the first serving DU configuration including configurations updating (e.g., augmenting, modifying or replacing) the serving DU configuration 402.
  • the first serving DU configuration includes configurations that are not included in the serving DU configuration 402.
  • the CU 172 transmits a RRC reconfiguration message including the first serving DU configuration to the UE 102.
  • the UE 102 applies the first serving DU configuration to communicate with the serving DU upon receiving the RRC reconfiguration message.
  • the RRC reconfiguration message is or is similar to the RRC reconfiguration message in procedure 494.
  • the UE 102 communicates with the S- DU 174A using configurations included in the serving DU configuration 402 and not updated by the first serving DU configuration.
  • the following are example embodiments of generating the first serving DU configuration based on the LTM DU configuration 1 , N.
  • the 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-MeasConfig IE and the CSI-MeasConfig IE includes the CSI-ResourceConfig I E(s).
  • the S-DU 174A generates at least one serving report configuration for reporting, on the cell 124A, 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. In some embodiments, the S-DU 174A includes the RS resource configuration(s) Y in the serving RS resource configuration(s). In other embodiments, the S-DU 174A includes each of the RS resource configuration(s) Y in the serving RS resource configuration(s), except the RS resource configuration ID(s) in the RS resource configuration(s) Y. The S-DU 174A assigns a RS resource configuration ID to a value for each of the serving RS resource configuration(s) (including the RS resource configuration(s) Y) and includes the RS resource configuration ID in the corresponding serving RS resource configuration.
  • 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 174A, 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.
  • the 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 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 L1-RSRP values and/or one or more L1-SINR values.
  • the LTM DU configuration Y of the procedure 490 includes at least one TCI state configuration Y, where 1 ⁇ Y ⁇ N.
  • Each of the TCI state configuration(s) Y configures a TCI state that associates or includes 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- ToAddModList-r17 ield, one or more TCI-UL-State-r17 lEs, a dl-OrJointTCI- StateToAddModList-r17 field, one or more TCI-State lEs, TCI-ActivatedConfig 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 configuration(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 configuration(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 command the UE 102 to perform a fast serving cell change to the cell Y.
  • the S-DU 174A 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 Y, where 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+1 , ... , 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+1 , ... , N+M and/or cell ID(s) N+1 , ..., N+M in the CU-to-DU message.
  • the CU 172 may perform multiple LTM ID transfer procedures to transmit the ID(s) N+1 , ..., N+M, cell ID(s) N+1 , ... , N+M and/or LTM DU configuration(s) N+1 , ... , N+M to the S-DU 174A.
  • 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 174A associates the ID(s) N+1 , ..., N+M with the LTM DU configuration(s) N+1 , ... , N+M and/or the cell ID(s) N+1 , ... , N+M, respectively.
  • the S-DU 174A generates a second serving DU configuration, based on the LTM DU configuration(s) N+1 , N+2, ... , and/or N+M, and includes the second serving DU configuration in the DU-to-CU message.
  • the second serving DU configuration including 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 CU 172 transmits an RRC reconfiguration message including the second serving DU configuration to the UE 102 via the S-DU 174A.
  • the UE 102 applies the second serving DU configuration to communicate with the serving DU upon receiving the RRC reconfiguration message.
  • the RRC reconfiguration message is or is similar to the RRC reconfiguration message in procedure 494.
  • UE 102 communicates with the S-DU 174A using configurations included in the serving DU configuration 402 and/or the first serving DU configuration and not updated by the second serving DU configuration.
  • the S-DU 174A generates one or more new L1 measurement configurations, based on L1 measurement configuration(s) in the LTM DU configuration(s) N+1 , N+2, ... , and/or N+M, and includes the new L1 measurement configuration(s) in the second serving DU configuration.
  • the S-DU 174A generates one or more new TCI state configuration, based on TCI state configuration(s) in the LTM DU configuration(s) N+1 , 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+1 , ..., N+M described for the scenario 400.
  • value(s) of the cell I D(s) 1 , ... , N of the procedure 380 are different from value(s) of the cell I D(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+1 , ... , N+M described for the scenario 400.
  • the UE 102 might transmit 424 at least one measurement report to the S-DU 174A, similar to the event 324.
  • the at least one measurement report (e.g., L1 measurement report(s)) includes an event ID, first measurement result(s) for the cell 1 of the T-DU 174B, and/or includes second measurement result(s) for the cell 124A.
  • the first measurement result(s) may be or include RSRP, RSRQ and/or SINR that the UE 102 obtains from reference signal(s) transmitted on cell 1.
  • the second measurement result(s) may be or include RSRP, RSRQ and/or SINR that the UE 102 obtains from reference signal(s) transmitted on cell 124A.
  • the event ID, RSRP, RSRQ and/or SINR are L1-event ID, L1-RSRP, L1-RSRQ and/or L1-SINR, respectively.
  • the S-Dll 174A might transmit 430 a first LTM command (i.e. , LTM command 1) including the ID 1 to the UE 102 to order the UE 102 to perform a serving cell change to the cell 1 of the T-Dll 174B.
  • the first LTM command includes the ID 1 (i.e., LTM ID).
  • the first LTM command includes the cell index 1.
  • the UE 102 When 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. After (e.g., in response to) receiving the first LTM command, the UE 102 might or might not perform 432 an RA procedure with the T-DU 174B, similar to the event 332. After (e.g., in response to) receiving the first LTM command or completing the RA procedure 432, the UE 102 might 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.
  • the serving cell may be the cell 1 or cell 2 of the S-DU 174A. Otherwise, if no serving cell change occurs in the 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 LTM ID 1 , as described for 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 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 LTM ID 1 in the DU-to-CU message 429 to indicate that the S-DU 174A is to activate the LTM DU configuration 1 or trigger an 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-Dll 174B detects that UE 102 accesses cell 1 , the T-Dll 174B transmits the DL data to the UE 102 via the 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
  • the events 380, 404, 406, 490, 492, 494, 494, 424, 426, 428, 429, 430, 431 , 432, 434, 436, 496, 498, and 456 are collectively referred to in FIG. 4 as an LTM configuration and/or activation procedure 480.
  • the second BS 106 operates as an MN
  • 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.
  • the UE 102 in DC communicates with the 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 the event 302.
  • the 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 a 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 an LTM DU configuration and/or activation procedure with the UE 102, similar to the procedures 380 and/or 480.
  • the UE 102 may transmit the 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.
  • the 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 for FIG. 3.
  • the events 590, 592, 594, 524, 526, 528, 529, 530, 531 , 532, 534, 536, 596, 598, and 556 are similar to the events 390, 392, 394, 324, 326, 328, 329, 330, 331 , 332, 334, 336, 396, 398, and 356, respectively.
  • 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.
  • the DU 174 and/or CU 172 may perform the LTM execution procedure 598 with the UE 102 to command the UE 102 to perform a cell change from the first cell to the second cell, similar to the procedure 398 or 498.
  • 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.
  • the events 504, 506, 505, 507, 590, 592, 594, 524, 526, 528, 529, 530, 531 , 532, 534, 536, 596, 598, and 556 are collectively referred to in FIG. 5A as an LTM DU configuration and/or activation procedure 581.
  • a scenario 500B is generally similar to the scenario 500A, 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 517, 519 is similar to the RRC reconfiguration message 316, 318.
  • the RRC reconfiguration complete message 521 , 523 is similar to the RRC reconfiguration message 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.
  • the UE 102 generates a MN RRC response message including the RRC reconfiguration complete message and transmits 521 the MN RRC response message to the 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, 556 are collectively referred to in FIG. 5B as an LTM DU configuration and/or activation procedure 582.
  • the 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-Dll 174A and a T-Dll 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.
  • the CU 172 may perform 681 an LTM DU configuration and/or activation procedure with the UE 102 via the M-DU 174A or S-DU 174B, similar to the procedure 581 or 582.
  • a scenario 600B similar to the scenarios 300- 500B and 600A, 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) 174A 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 the event 302.
  • Events 704 and 706 are similar to the events 304 and 306.
  • the UE 102 may transmit 705 at least one measurement report to the M-DU 174A, similar to the event 304.
  • the M-DU 174A transmits 707 at least one DU-to-CU message including the at les tone measurement report to the CU 172, similar to the event 306.
  • 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, and 756 are collectively referred to in FIG. 7A as an LTM configuration and/or activation procedure 781.
  • a scenario 700B similar to the scenarios 300- 600B and 700A, except that that the CU 172 transmits 717, 719 the RRC reconfiguration message to the UE 102 via the M-Dll 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, and 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 an 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.
  • FIG. 8B a scenario 800B similar to the scenarios 300- 700B and 800A, 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-14 several example methods, which may be implemented in a UE, for LTM, are discussed next with reference to FIGs. 9A-14. The scenarios discussed above with regard to FIGs. 3-8B may apply to FIGs. 9A-14.
  • FIG. 9A illustrates an example method 900A, which may be implemented by a UE (e.g., the UE 102).
  • the method 900A begins at block 902, where the UE communicates with a RAN (e.g., RAN 105) or a NE of the RAN (e.g., NE 107) via a serving cell 124A (e.g., events 302, 402, 502, 602, 702, and 802).
  • the UE uses a MAC entity to communicate with the RAN 105 and the MAC entity performs operations of the MAC layer.
  • the UE receives 904 an LTM candidate configuration from the RAN 105, where the LTM candidate configuration configures a candidate cell 124B (e.g., event 316, 318, 394, 494, 594, 517, 519, 694, 617, 619, 794, 717, 719, 894, 817, or 819).
  • the LTM candidate configuration includes an LTM DU configuration that configures the candidate cell as described above.
  • the serving cell is a serving PCell and the candidate cell is a candidate PCell.
  • the serving cell is a serving PSCell and the candidate cell is a candidate PSCell.
  • the LTM candidate configuration is an LTM-Candidate IE.
  • the LTM candidate configuration is an LTM-CandidateConfig IE.
  • the LTM candidate configuration includes an LTM ID (i.e., a configuration ID) identifying the LTM candidate configuration or the LTM DU configuration.
  • the UE receives 906 an LTM command from the RAN via the serving cell, and the LTM command includes CFRA resources information (e.g., event 330, 430, 530, 630, 730, or 830).
  • the LTM command includes the LTM ID and the UE identifies the LTM candidate configuration in accordance with the LTM ID.
  • the LTM command includes an LTM configuration index derived or mapped from the LTM ID.
  • the LTM configuration index is the LTM ID minus one. For example, if the LTM ID is set to value N, the LTM configuration index may be the value N-1.
  • the UE identifies the LTM candidate configuration in accordance with the LTM configuration index and the mapping between the LTM configuration index and the LTM ID.
  • the UE performs 908A a MAC reset in response to the LTM command including the CFRA resource information.
  • the UE performs the MAC reset for communication with the RAN on the candidate cell.
  • the UE resets 908A the MAC entity used for communication with the RAN on the candidate cell, when performing the MAC reset.
  • the UE is configured to retain 910 the CFRA resources information when (e.g., in response to) performing the MAC reset. That is, the UE refrains from discarding the CFRA resources information upon performing the MAC reset as the CFRA resources information is valuable for the RA procedure.
  • the UE then performs 912 the RA procedure on the candidate cell based on the (retained) CFRA resources information, also in response to the LTM command (e.g., event 332, 432, 532, 632, 732, or 832).
  • the CFRA resources information reduces a latency of the UE as there is no need for waiting for the contention resolution. This is advantageous for a class of devices that require a very low latency.
  • the UE After completing the RA procedure, the UE communicates 922 with the RAN via the candidate cell, using the LTM candidate configuration (e.g., event 336, 436, 536, 636, 736, or 836). In some embodiments after resetting the MAC entity, the UE communicates 922 with the RAN using the MAC entity. In some embodiments, the UE discards the CFRA resources information after completing the RA procedure.
  • the LTM candidate configuration e.g., event 336, 436, 536, 636, 736, or 836.
  • the CFRA resources information configures CFRA resources for the UE to perform the RA procedure (i.e., CFRA procedure).
  • the CFRA resources information includes at least one of a random access preamble index, a UL or SUL indicator, a SSB index and/or a PRACH mask index.
  • the UE selects a random access preamble indicated by the random access preamble index and determines a PRACH occasion based on the PRACH mask index and/or the LTM DU configuration.
  • the term “PRACH occasion” refers to a specific time instance or time slot when the UE may access the PRACH to initiate communication with the RAN.
  • the UE transmits the random access preamble to the RAN on the PRACH occasion.
  • the UE may select a carrier frequency (i.e., a UL carrier frequency or a SUL carrier frequency) in accordance with the UL or SUL indicator and/or the LTM DU configuration.
  • the LTM DU configuration may include a first configuration (e.g., a UL configuration) and/or a second configuration (e.g., a SUL configuration).
  • the first configuration configures the UL carrier frequency
  • the second configuration configures the SUL carrier frequency. If the UL or SUL indicator indicates “UL”, the UE transmits the random access preamble to the RAN on the PRACH occasion on the UL carrier frequency.
  • the UE transmits the random access preamble to the RAN on the PRACH occasion on the SUL carrier frequency.
  • the first configuration includes a first UL bandwidth part (BWP) configuration and/or a second UL BWP configuration.
  • the first BWP configuration configures a UL BWP (i.e., a BWP on or within the UL carrier frequency) and the second BWP configuration configures a SUL BWP (i.e., a BWP on or within the UL carrier frequency). If the UL or SUL indicator indicates “UL”, the UE transmits the random access preamble to the RAN on the PRACH occasion on the UL BWP.
  • the UE transmits the random access preamble to the RAN on the PRACH occasion on the SUL BWP. In some alternative embodiments, the UE transmits the random access preamble to the RAN on the PRACH occasion on the UL BWP and/or the UL carrier frequency regardless of the UL or SUL indicator. In other words, the UE ignores the UL or SUL indicator, e.g., because the UE does not support SUL.
  • the UE may determine a transmission beam (i.e. , transmission characteristics) based on the SSB index.
  • the RAN may include, in the LTM DU configuration, association information indicating association between the random access preamble and the SSB (index).
  • the UE transmits the random access preamble to the RAN on the PRACH occasion using the transmission beam.
  • the UE stops any ongoing RA procedure when performing a MAC reset. If the UE performs the MAC reset while performing the RA procedure (i.e., LTM cell switch to the candidate cell from the serving cell), the UE stops the RA procedure because of the MAC reset and this causes a failure of the LTM cell switch. With the method 900A, the UE performs the RA procedure after performing the MAC reset, which prevents this failure. In addition, because the UE is configured to retain the CFRA resources information when performing the MAC reset, the latency associated with the RA procedure is reduced as there is no contention resolution procedure to be performed.
  • the UE is configured to retain the CFRA resources information when performing the MAC reset, the latency associated with the RA procedure is reduced as there is no contention resolution procedure to be performed.
  • FIG. 9B is a flow diagram of an example method 900B similar to the method 900A, except that the method 900B includes blocks 908B and 911 instead of block 910.
  • the flow proceeds to block 912 directly from block 906 (in this way, the CFRA resources information is used for the RA procedure before being discarded by the MAC reset) and then proceeds to block 908B from block 912.
  • the UE performs 908B the MAC reset in response to the LTM command, after completing 912 the RA procedure.
  • the UE discards 911 the CFRA resources information when performing the MAC reset.
  • the UE is configured to perform and complete the RA procedure before discarding the CFRA resources information triggered by the MAC reset.
  • the order of performing the RA procedure first and the MAC reset second ensures that the CFRA resources information is available during the RA procedure for a quick cell switch.
  • FIG. 10A illustrates an example method 1000A which may be implemented by a UE (e.g., the UE 102).
  • the method 1000A begins with blocks 902, 904, 906, 908A, and 910 as described in FIG. 9A.
  • the UE After performing the MAC reset, the UE initiates 1012A an RA procedure on the candidate cell in response to the LTM command (e.g., event 332, 432, 532, 632, 732 or 832).
  • the UE transmits 1014 a random access preamble on the candidate cell to the RAN using the CFRA resources information, in response to initiating the RA procedure.
  • the CFRA resources information is used by the UE to send a random access preamble to the RAN to avoid a contention procedure.
  • the UE selects the random access preamble indicated by a random access preamble index in the CFRA resources information.
  • the UE receives 1016 a random access response (RAR) on the candidate cell from the RAN in response to the random access preamble, and the RAR includes a TA value.
  • the RAN may include the random access preamble index to resolve the contention.
  • the UE applies 1018 the TA value to UL synchronization with the candidate cell. After applying the TA value to UL transmission timing with the candidate cell, the UE is UL synchronized with the candidate cell.
  • the UE starts 1020 a time alignment timer for maintaining (e.g., counting) a valid period of the UL synchronization as the MAC reset has stopped all the timers.
  • the time alignment timer is running before the RAR is received, because the UE starts the time alignment timer for maintaining a valid period of UL synchronization with the serving cell at block 902. In such cases, the UE restarts 1020 the time alignment timer.
  • the method proceeds to block 922 from block 1020, where the UE communicates 922 with the RAN via the candidate cell, using the LTM candidate configuration.
  • the UE transmits UL transmissions on the candidate cell in accordance with the UL transmission timing.
  • the UE continuously adjusts the UL transmission timing based on DL signals received on the candidate cell.
  • the UL transmissions includes PUSCH transmissions and PUCCH transmissions. In other embodiments, when receiving an TA command, the UE adjusts the UL transmission timing based on the TA command.
  • Examples and embodiments described with regard to FIG. 9A may apply to FIG. 10A.
  • the UE selects and transmits the random access preamble based on the CFRA resources information as described in FIG. 9A.
  • the UE receives the RAR in accordance with the PRACH occasion and/or the LTM candidate configuration (e.g., the LTM DU configuration).
  • FIG. 10B is a flow diagram of an example method 1000B similar to the method 1000A, except that the method 1000B includes blocks 1007, 1011 , and 1012B instead of block 1012A.
  • the flow begins with blocks 902, 904, and 906 as described in FIG. 9A.
  • the flow proceeds to block 1007 where the UE refrains from initiating an RA procedure on the candidate cell in response to the LTM command.
  • another event (not the LTM command) is used to trigger the RA procedure.
  • the flow proceeds from block 1007 to blocks 908A and 910 discussed above. Because of block 1007, the UE does not stop an RA procedure for an LTM cell switch to the candidate cell, when the UE performs 908A the MAC reset.
  • Block 1007 only prevents the UE to initiate the RA procedure in response to the LTM command. However, this block does not prevent the UE to initiate the RA procedure in response to other events. For example, the UE initiates 1011 transmission of a UL PDU after performing the MAC reset. The UE initiates 1012B the RA procedure on the candidate cell in response to initiating transmission of the UL PDU (e.g., event 332, 432, 532, 632, 732 or 832) instead of the LTM command.
  • the UL PDU is a RLC PDU, a PDCP PDU, or a RRC PDU.
  • the UL PDU includes an RRC message (e.g., a RRC reconfiguration complete message).
  • the UE transmits the RRC message in response to the LTM command (i.e., executing the LTM cell switch).
  • the RA procedure is not triggered by the LTM command, but rather by another event, e.g., the transmission of the UL PDU.
  • FIG. 10C is a flow diagram of an example method 1000C similar to the methods 1000A and 1000B, except that the method 1000C includes blocks 1021 and 1012C instead of blocks 1011 , 1012A, and 1012B.
  • the UE initiates 1021 a MAC procedure after performing the MAC reset.
  • the MAC procedure is the event that will trigger the RA procedure in this embodiment.
  • the UE initiates 1012C the RA procedure on the candidate cell in response to initiating the MAC procedure (e.g., event 332, 432, 532, 632, 732 or 832).
  • the MAC procedure is a buffer status reporting procedure.
  • the UE generates a buffer status report including data volume in a buffer when initiating the buffer status reporting procedure.
  • the UE transmits the buffer status report to the RAN, on the candidate cell, after completing the RA procedure.
  • the UE receives DCIs from the RAN on PDCCH(s) on the candidate cell and the DCIs schedules UL transmissions.
  • the UE transmits UL transmissions to the RAN on the candidate cell in accordance with the DCIs.
  • the MAC procedure is a power headroom reporting procedure.
  • the UE generates a power headroom report indicating available transmit power when initiating the buffer status reporting procedure.
  • FIG. 11 A illustrates an example method 1100A, which may be implemented by a MAC entity (e.g., MAC layer or controller 158) of a UE (e.g., the UE 102).
  • a MAC entity e.g., MAC layer or controller 158 of a UE (e.g., the UE 102).
  • the method 1100A begins at block 1106, where the MAC entity receives an LTM command from a RAN via a physical layer (e.g., PHY layer or controller 156), where the LTM command includes CFRA resources information (e.g., event 330, 430, 530, 630, 730, or 830).
  • the MAC entity sends 1105 an indication to an RRC layer (e.g., RRC layer or controller 160) to indicate executing an LTM cell switch, in response to receiving the LTM command.
  • the LTM command includes an LTM ID as described above
  • the MAC entity provides the LTM ID in the indication.
  • the RRC layer identifies an LTM candidate configuration or an LTM DU configuration based on the LTM ID.
  • the MAC entity indicates the LTM configuration index in the indication and the RRC layer identifies an LTM candidate configuration or an LTM DU configuration based on the LTM configuration index and a mapping between the LTM configuration index and an LTM ID as described above. Alternatively, the MAC entity determines an LTM ID from the LTM configuration index and the mapping and indicates the LTM ID in the indication.
  • the MAC entity receives 1109 a MAC reset indication from the RRC layer after transmitting 1105 the indication.
  • the MAC entity performs 1108C a MAC reset in response to the MAC reset indication.
  • the MAC entity retains 1110 the CFRA resources information when (e.g., in response to) performing the MAC reset.
  • the MAC entity After performing the MAC reset, the MAC entity initiates 1112A an RA procedure with the RAN on a candidate cell in response to the LTM command (e.g., event 332, 432, 532, 632, 732 or 832).
  • the MAC entity sends 1114A an indication to the physical layer in response to initiating the RA procedure, where the indication requests sending a random access preamble on the candidate cell in accordance with the CFRA resources information.
  • the MAC entity indicates or includes the CFRA resources information in the indication.
  • the physical layer transmits a random access preamble in accordance with the CFRA resources information and/or the LTM DU configuration as described in FIG. 9A.
  • the MAC entity receives 1116A a RAR on the candidate cell, from the RAN, via the physical layer, in response to the random access preamble.
  • the RAR includes a TA value (e.g., event 332, 432, 532, 632, 732 or 832).
  • the MAC entity sends 1119 the TA value to the physical layer for UL synchronization with the candidate cell.
  • the MAC entity performs UL synchronization with the candidate cell instead of the physical layer, and thus, the MAC entity applies the TA value to UL synchronization with the candidate cell.
  • the MAC entity starts 1120 a time alignment timer for maintaining a valid period of the UL synchronization.
  • Examples and embodiments described above for the UE in FIGs. 9A and 10A may apply to the MAC entity in FIG. 11 A.
  • FIG. 11 B is a flow diagram of an example method 1100B similar to the method 1100A, except that the method 1100B includes blocks 1107, 1111 A, and 1112B instead of block 1112A.
  • the UE refrains 1107 from initiating an RA procedure on the candidate cell in response to the LTM command. Another event will trigger the RA procedure.
  • the MAC entity initiates transmission 1111 A of a UL PDU after performing the MAC reset.
  • the MAC entity initiates 1112B the RA procedure on the candidate cell in response to initiating the transmission of the UL PDU (e.g., event 332, 432, 532, 632, 732 or 832). Examples and embodiments described for the UE in FIGs. 9A, 9B, 10A, and 10B may apply to the MAC entity in FIG. 11 B.
  • FIG. 11 C is a flow diagram of an example method 1100C similar to the methods 1100A and 1100B, except that the method 1100C includes blocks 1121 and 1112C instead of blocks 1111 A, 1112A, and 1112B.
  • the MAC entity initiates 1121 a MAC procedure after performing the MAC reset.
  • the MAC entity initiates 1112C the RA procedure on the candidate cell in response to initiating the MAC procedure (e.g., event 332, 432, 532, 632, 732 or 832). Examples and embodiments described for the UE in FIGs. 9A, 9B, 10A, 10B, and 10C may apply to the MAC entity in FIG. 11C.
  • FIG. 11 D is a flow diagram of an example method 1100D similar to the methods 1100A, 1100B, and 1100C, except that the method 1100D includes blocks 1131 and 1112D instead of blocks 1111A, 1112A, 1112B, and 1112C.
  • the MAC entity receives 1131 an RA request from the RRC layer after performing the MAC reset.
  • the MAC entity initiates 1112D the RA procedure on an LTM candidate cell in response to the RA request (e.g., event 332, 432, 532, 632, 732 or 832).
  • the MAC entity receives the RA request after receiving the MAC reset indication and before performing the MAC reset and initiates the RA procedure after performing 1108C the MAC reset.
  • the RA request is combined with or included in the MAC reset indication and the MAC entity initiates the RA procedure after performing 1108C the MAC reset. Examples and embodiments described for the UE in FIGs. 9A, 9B, 10A, 10B, and 10C may apply to the MAC entity in FIG. 11 D.
  • FIG. 12 illustrates an example method 1200, which may be implemented by a UE (e.g., the UE 102).
  • the method 1200 begins at block 1206 where the UE receives CFRA resources information (e.g., event 330, 430, 530, 630, 730, or 830).
  • CFRA resources information e.g., event 330, 430, 530, 630, 730, or 830.
  • the UE performs 1208 a MAC reset.
  • the UE determines 1230 whether the UE has received the CFRA resources information in an LTM command or a message other than an LTM command.
  • the UE determines 1230 that the UE has received the CFRA resources information in a message other than the LTM command (e.g., the UE has received the CFRA resources information in a PDCCH order or in a RRC message), the UE discards 1211 the CFRA resources information in response to the MAC reset. Otherwise, if the UE determines that the UE received the CFRA resources information in the LTM command, the UE retains 1210 the CFRA resources information in response to the MAC reset so that a subsequent RA procedure can take advantage of the CFRA resources information, as discussed above. Examples and embodiments described for FIGs. 9A, 9B, 10A, 10B, and 10C may apply to FIG. 12.
  • FIG. 13A illustrates an example method 1300A, which may be implemented by a UE (e.g., the UE 102).
  • the method 1300A begins at block 1206 as described in FIG. 12.
  • the UE determines 1332 whether the UE has received the CFRA resources information in a PDCCH order or LTM command. If the UE determines 1332 that the UE has received the CFRA resources information in a PDCCH order, the UE immediately initiates 1334 an RA procedure in response to the PDCCH order.
  • the term “immediate” in this embodiment refers to starting the RA procedure without performing other procedures.
  • the UE determines 1334 that the UE has received the CFRA resources information in an LTM command, the UE performs 1312 first a MAC reset and then initiates the RA procedure in response to the LTM command. This is an example of not “immediately” starting the RA procedure as the MAC reset is performed before the RA procedure.
  • FIG. 13B is a flow diagram of an example method 1300B similar to the method 1300A, except that the method 1300B includes block 1313 instead of block 1312. If the UE determines 1332 that the UE has received the CFRA resources information in an LTM command, the UE refrains 1313 from immediately initiating an RA procedure in response to the LTM command and rather waits for another trigger event. In some embodiments, to perform an LTM cell switch indicated in the LTM command, the UE initiates an RA procedure in response to an event as described in FIGs. 10B, 10C, 11 B, 11 C, or 11 D. Examples and embodiments described for FIGs. 9A, 9B, 10A, 10B, and 10C may apply to FIGs. 13A and 13B.
  • the methods 1300A and 1300B may be described as follows.
  • the UE receives 1332 from the NE 107, via a serving cell 124A, CFRA resources information, then initiates 1334 an RA procedure when the CFRA resources information is received in a PDCCH order, and then initiates 1312 the RA procedure when the CFRA resources information is received in an LTM command.
  • the method may further include performing a MAC reset, where the initiating of the RA procedure is after the MAC reset.
  • the method may also include initiating the RA procedure based on an event different from the LTM command.
  • FIG. 14 illustrates an example method 1400, which may be implemented by a UE (e.g., the UE 102).
  • the method 1400 begins at block 1440, where the UE initiates an RA procedure using a MAC entity (e.g., event 332, 432, 532, 632, 732, or 832).
  • the UE resets 1442 the MAC entity during the RA procedure.
  • the UE determines 1444 whether the RA procedure is initiated for an LTM cell switch. If the UE determines 1444 that the RA procedure is not initiated for an LTM cell switch, the UE stops 1446 the RA procedure. Otherwise, if the UE determines 1444 that the RA procedure is initiated for an LTM cell switch, the UE continues 1448 the RA procedure. Steps 912 and 922 discussed above with regard to FIG. 9A may be performed after step 1448. Examples and embodiments described for FIGs. 9A, 9B, 10A, 10B, and 10C may apply to FIG. 14.
  • the method 1400 includes resetting 1444 a MAC entity during an RA procedure, continuing 1448 the RA procedure when the RA procedure is for an LTM cell switch, and stopping 1446 the RA procedure otherwise.
  • the term “message” is used and may be replaced by “information element (IE),” and vice versa.
  • IE information element
  • IE is used and may be replaced by “field,” and vice versa.
  • configuration may be replaced by “configurations” or “configuration parameters,” and vice versa.
  • the term “LTM command” may be replaced by “serving cell change command,” “layer 1/layer 2 LTM cell switch command,” “lower layer switching command,” or “lower layer serving cell change command.”
  • the term “some” means “one or more.”
  • “at least one” means “one or more.”
  • the “DU configuration” may be replaced by “cell group configuration.”
  • the “cell index” may be replaced with “serving cell index,” “LTM cell index,” “special cell (SpCell) index,” “PCell index,” or SCell index.”
  • the term “serving” may be replaced by “source.”
  • the “measurement report” may be replaced by “measurement result(s)” or “CSI report.”
  • the “early TA acquisition” may be replaced by “early UL timing synchronization” or “early UL synchronization.”
  • the “early TA acquisition on a/the candidate cell” may be
  • a user device in which the techniques of this document may be implemented may be any suitable device capable of wireless 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 internet- 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.
  • 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 include 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 include 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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Abstract

Selon l'invention, des procédés et des dispositifs fonctionnent dans un réseau d'accès radio pour permettre un changement rapide de cellule de desserte à l'aide d'une procédure de mobilité déclenchée par couche inférieure (LTM), ce qui réduit la latence et le surdébit par rapport à des procédures de commutation de cellule déclenchée par la couche supérieure. Une commande LTM reçue par un équipement utilisateur (UE) comprend des informations de ressources d'accès aléatoire sans contention (CFRA). Une procédure d'accès aléatoire permettant de commuter une cellule de desserte à une cellule candidate, en réponse à un événement, est effectuée sur la base des informations de ressources CFRA. L'événement peut être l'un des éléments suivants : la commande LTM, une unité de données de protocole de liaison montante, une procédure de commande d'accès au support ou un ordre de canal physique de contrôle descendant.
PCT/US2024/056193 2023-12-01 2024-11-15 Mobilité déclenchée par couche inférieure avec informations d'accès aléatoire sans contention Pending WO2025117217A1 (fr)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024096575A1 (fr) * 2022-11-02 2024-05-10 Samsung Electronics Co., Ltd. Procédé et appareil de gestion de libération de ressource de cfra pour une mobilité basée sur une signalisation l1 dans un système de communication sans fil

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WO2024096575A1 (fr) * 2022-11-02 2024-05-10 Samsung Electronics Co., Ltd. Procédé et appareil de gestion de libération de ressource de cfra pour une mobilité basée sur une signalisation l1 dans un système de communication sans fil

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