WO2024234222A1

WO2024234222A1 - Lower-layer triggered mobility procedure in a wireless communication system

Info

Publication number: WO2024234222A1
Application number: PCT/CN2023/094154
Authority: WO
Inventors: Yushu Zhang; Jia-Hong Liou
Original assignee: Google LLC
Current assignee: Google LLC
Priority date: 2023-05-15
Filing date: 2023-05-15
Publication date: 2024-11-21
Anticipated expiration: 2025-11-15
Also published as: CN121176085A

Abstract

This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for a lower-layer triggered mobility (LTM) procedure in a wireless communication system. A UE (102) receives (314), from a network entity (104), a cell-switching command (CSC) for a UE group, where the UE (102) may be a member of the UE group. The CSC includes an indication for the UE (102) to switch from a source cell to a candidate cell. The UE (102) performs (320), with the network entity (104), the LTM procedure to switch the UE (102) from the source cell to the candidate cell based on the indication included in the CSC for the UE group.

Description

LOWER-LAYER TRIGGERED MOBILITY PROCEDURE IN A WIRELESS COMMUNICATION SYSTEM

TECHNICAL FIELD

The present disclosure relates generally to wireless communication, and more particularly, to a lower-layer triggered mobility (LTM) procedure.

BACKGROUND

The Third Generation Partnership Project (3GPP) specifies a radio interface referred to as fifth generation (5G) new radio (NR) (5G NR) . An architecture for a 5G NR wireless communication system includes a 5G core (5GC) network, a 5G radio access network (5G-RAN) , a user equipment (UE) , etc. The 5G NR architecture seeks to provide increased data rates, decreased latency, and/or increased capacity compared to prior generation cellular communication systems.

Wireless communication systems, in general, provide various telecommunication services (e.g., telephony, video, data, messaging, broadcasts, etc. ) based on multiple-access technologies, such as orthogonal frequency division multiple access (OFDMA) technologies, that support communication with multiple UEs. Improvements in mobile broadband continue the progression of such wireless communication technologies. For example, lower-layer triggered mobility (LTM) procedures may reduce latency associated with UE handovers by using a cell-switching command (CSC) that triggers the UE to switch from a source cell to an already-configured candidate cell. However, when multiple UEs are simultaneously moving along a same or similar trajectory, independent CSC transmissions to each of the multiple UEs may include redundant information that unnecessarily increases the signaling overhead.

BRIEF SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects. This summary neither identifies key or critical elements of all aspects nor delineates the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

A user equipment (UE) and a network entity, such as a base station of a unit of a base station, may implement a lower-layer triggered mobility (LTM) procedure to reduce latency associated with handover/cell-switching procedures of the UE. For example, in comparison to a Layer 3 (L3) cell-switching procedure, which may have increased latency as a result of multiple higher layer message exchanges and reconfiguration, a Layer 1/Layer 2 (L1/L2) cell switching procedure may be based on triggering a candidate cell configured to the UE, where the candidate cell is configured via a UE configuration message. The network entity may configure the UE with one or more candidate cells prior to transmitting a cell-switching command (CSC) to the UE, so that when the UE moves from a source cell toward a configured candidate cell, or a cell quality of the configured candidate cell has a higher quality than a source cell, the network entity can transmit the CSC to the UE for the UE to switch from the source cell to the configured candidate cell with reduced latency.

In cases where at least multiple UEs are simultaneously moving toward a same candidate cell, transmitting independent CSCs to each of the multiple UEs may be redundant and/or may result in high signaling overhead. An example of multiple UEs simultaneously moving toward a same candidate cell includes a same vehicle carrying the multiple UEs and traveling with the multiple UEs along a same road or trajectory. Oftentimes, independent CSC transmissions to such UEs include the same or similar information. Hence, the signaling overhead is increased based on the network entity transmitting, to each of the multiple UEs, separate CSCs that include the same or similar information.

Aspects of the present disclosure address the above-noted and other deficiencies based on the network entity transmitting a group-common CSC (GC-CSC) to the multiple UEs (e.g., as a UE group) to reduce signaling overhead with the multiple UEs. The GC-CSC includes cell switching information applicable to each of the multiple UEs, either jointly to the UE group as a whole or based on separately dedicated UE-specific portions of the GC-CSC, so that the network entity can transmit one CSC transmission to switch the cells for all or some of the multiple UEs in the UE group.

According to some aspects, the UE receives, from the network entity, a CSC for a UE group. The CSC includes an indication for the UE to switch from a source cell to a candidate cell. The UE performs, with the network entity, an LTM procedure to switch the UE from the source cell to the candidate cell based on the indication included in the CSC for the UE group.

According to some aspects, the network entity transmits, to the UE, the CSC for the UE group that includes the UE. The CSC further includes an indication to switch the UE from the source cell to the candidate cell. The network entity performs, with the UE, the LTM procedure to switch the UE from the source cell to the candidate cell according to the indication included in the CSC for the UE group.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram of a wireless communications system that includes a plurality of user equipments (UEs) and network entities in communication over one or more cells.

FIG. 2 illustrates a diagram of a base station transmitting a cell-switching command (CSC) to one or more UEs.

FIG. 3 illustrates a signaling diagram for configuring and implementing a group-common CSC (GC-CSC) .

FIG. 4 is a flowchart of a method of wireless communication at a UE.

FIG. 5 is a flowchart of a method of wireless communication at a network entity.

FIG. 6 is a diagram illustrating a hardware implementation for an example UE apparatus.

FIG. 7 is a diagram illustrating a hardware implementation for one or more example network entities.

DETAILED DESCRIPTION

FIG. 1 illustrates a diagram 100 of a wireless communications system associated with a plurality of cells 190. The wireless communications system includes user equipments (UEs) 102 and base stations/network entities 104. Some base stations may include an aggregated base station architecture and other base stations may include a disaggregated base station architecture. The aggregated base station architecture utilizes a radio protocol stack that is physically or logically integrated within a single radio access network (RAN) node. A disaggregated base station architecture utilizes a protocol stack that is physically or logically distributed among two or more units (e.g., radio unit (RU) 106, distributed unit (DU) 108, central unit (CU) 110) . For example, a CU 110 is implemented within a RAN node, and one or more DUs 108 may be co-located with the CU 110, or alternatively, may be geographically or virtually distributed throughout one or multiple other RAN nodes. The DUs 108 may be implemented to communicate with one or more RUs 106. Any of the RU 106, the DU 108 and the CU 110 can be implemented as virtual units, such as a virtual radio unit (VRU) , a virtual distributed unit (VDU) , or a virtual central unit (VCU) . The base station/network entity 104 (e.g., an aggregated base station or disaggregated units of the base station, such as the RU 106 or the DU 108) , may be referred to as a transmission reception point (TRP) .

Operations of the base station 104 and/or network designs may be based on aggregation characteristics of base station functionality. For example, disaggregated base station architectures are utilized in an integrated access backhaul (IAB) network, an open-radio access network (O-RAN) network, or a virtualized radio access network (vRAN) , which may also be referred to a cloud radio access network (C-RAN) . Disaggregation may include distributing functionality across the two or more units at various physical locations, as well as distributing functionality for at least one unit virtually, which can enable flexibility in network designs. The various units of the disaggregated base station architecture, or the disaggregated RAN architecture, can be configured for wired or wireless communication with at least one other unit. For example, the base stations 104d/104e and/or the RUs 106a-106d may communicate with the UEs 102a-102d and 102s via one or more radio frequency (RF) access links based on a Uu interface. In examples, multiple RUs 106 and/or base stations 104 may simultaneously serve the UEs 102, such as by intra-cell and/or inter-cell access links between the UEs 102 and the RUs 106/base stations 104.

The RU 106, the DU 108, and the CU 110 may include (or may be coupled to) one or more interfaces configured to transmit or receive information/signals via a wired or wireless transmission medium. For example, a wired interface can be configured to transmit or receive the information/signals over a wired transmission medium, such as via the fronthaul link 160 between the RU 106d and the baseband unit (BBU) 112 of the base station 104d associated with the cell 190d. The BBU 112 includes a DU 108 and a CU 110, which may also have a wired interface (e.g., midhaul link) configured between the DU 108 and the CU 110 to transmit or receive the information/signals between the DU 108 and the CU 110. In further examples, a wireless interface, which may include a receiver, a transmitter, or a transceiver, such as an RF transceiver, configured to transmit and/or receive the information/signals via the wireless transmission medium, such as for information communicated between the RU 106a of the cell 190a and the base station 104e of the cell 190e via cross-cell communication beams 136-138 of the RU 106a and the base station 104e.

The RUs 106 may be configured to implement lower layer functionality. For example, the RU 106 is controlled by the DU 108 and may correspond to a logical node that hosts RF processing functions, or lower layer PHY functionality, such as execution of fast Fourier transform (FFT) , inverse FFT (iFFT) , digital beamforming, physical random access channel (PRACH) extraction and filtering, etc. The functionality of the RU 106 may be based on the functional split, such as a functional split of lower layers.

The RUs 106 may transmit or receive over-the-air (OTA) communication with one or more UEs 102. For example, the RU 106b of the cell 190b communicates with the UE 102b of the cell 190b via a first set of communication beams 132 of the RU 106b and a second set of communication beams 134b of the UE 102b, which may correspond to inter-cell communication beams or, in some examples, cross-cell communication beams. For instance, the UE 102b of the cell 190b may communicate with the RU 106a of the cell 190a via a third set of communication beams 134a of the UE 102b and a fourth set of communication beams 136 of the RU 106a. DUs 108 can control both real-time and non-real-time features of control plane and user plane communications of the RUs 106.

Any combination of the RU 106, the DU 108, and the CU 110, or reference thereto individually, may correspond to a base station 104. Thus, the base station 104 may include at least one of the RU 106, the DU 108, or the CU 110. The base stations 104 provide the UEs 102 with access to a core network. The base stations 104 may relay communications between the UEs 102 and the core network (not shown) . The base stations 104 may be associated with macrocells for higher-power cellular base stations and/or small cells for lower-power cellular base stations. For example, the cell 190e may correspond to a macrocell, whereas the cells 190a-190d may correspond to small cells. Small cells include femtocells, picocells, microcells, etc. A network that includes at least one macrocell and at least one small cell may be referred to as a “heterogeneous network. ”

Transmissions from a UE 102 to a base station 104/RU 106 are referred to as uplink (UL) transmissions, whereas transmissions from the base station 104/RU 106 to the UE 102 are referred to as downlink (DL) transmissions. Uplink transmissions may also be referred to as reverse link transmissions and downlink transmissions may also be referred to as forward link transmissions. For example, the RU 106d utilizes antennas of the base station 104d of cell 190d to transmit a downlink/forward link communication to the UE 102d or receive an uplink/reverse link communication from the UE 102d based on the Uu interface associated with the access link between the UE 102d and the base station 104d/RU 106d.

Communication links between the UEs 102 and the base stations 104/RUs 106 may be based on multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be associated with one or more carriers. The UEs 102 and the base stations 104/RUs 106 may utilize a spectrum bandwidth of Y MHz (e.g., 5, 10, 15, 20, 100, 400, 800, 1600, 2000, etc. MHz) per carrier allocated in a carrier aggregation of up to a total of Yx MHz, where x component carriers (CCs) are used for communication in each of the uplink and downlink directions. The carriers may or may not be adjacent to each other along a frequency spectrum. In examples, uplink and downlink carriers may be allocated in an asymmetric manner, with more or fewer carriers allocated to either the uplink or the downlink. A primary component carrier and one or more secondary component carriers may be included in the component carriers. The primary component carrier may be associated with a primary cell (PCell) and a secondary component carrier may be associated with a secondary cell (SCell) .

Some UEs 102, such as the UEs 102a and 102s, may perform device-to-device (D2D) communications over sidelink. For example, a sidelink communication/D2D link utilizes a spectrum for a wireless wide area network (WWAN) associated with uplink and downlink communications. Such sidelink/D2D communication may be performed through various wireless communications systems, such as wireless fidelity (Wi-Fi) systems, Bluetooth systems, Long Term Evolution (LTE) systems, New Radio (NR) systems, etc.

The electromagnetic spectrum is often subdivided into different classes, bands, channels, etc., based on different frequencies/wavelengths associated with the electromagnetic spectrum. Fifth-generation (5G) NR is generally associated with two operating frequency ranges (FRs) referred to as frequency range 1 (FR1) and frequency range 2 (FR2) . FR1 ranges from 410 MHz -7.125 GHz and FR2 ranges from 24.25 GHz -71.0 GHz, which includes FR2-1 (24.25 GHz -52.6 GHz) and FR2-2 (52.6 GHz -71.0 GHz) . Although a portion of FR1 is actually greater than 6 GHz, FR1 is often referred to as the “sub-6 GHz” band. In contrast, FR2 is often referred to as the “millimeter wave” (mmW) band. FR2 is different from, but a near subset of, the “extremely high frequency” (EHF) band, which ranges from 30 GHz -300 GHz and is sometimes also referred to as a “millimeter wave” band. Frequencies between FR1 and FR2 are often referred to as “mid-band” frequencies. The operating band for the mid-band frequencies may be referred to as frequency range 3 (FR3) , which ranges 7.125 GHz -24.25 GHz. Frequency bands within FR3 may include characteristics of FR1 and/or FR2. Hence, features of FR1 and/or FR2 may be extended into the mid-band frequencies. Higher operating frequency bands have been identified to extend 5G NR communications above 52.6 GHz associated with the upper limit of FR2. Three of these higher operating frequency bands include FR2-2, which ranges from 52.6 GHz -71.0 GHz, FR4, which ranges from 71.0 GHz -114.25 GHz, and FR5, which ranges from 114.25 GHz -300 GHz. The upper limit of FR5 corresponds to the upper limit of the EHF band. Thus, unless otherwise specifically stated herein, the term “sub-6 GHz” may refer to frequencies that are less than 6 GHz, within FR1, or may include the mid-band frequencies. Further, unless otherwise specifically stated herein, the term “millimeter wave” , or mmW, refers to frequencies that may include the mid-band frequencies, may be within FR2-1, FR4, FR2-2, and/or FR5, or may be within the EHF band.

The UEs 102 and the base stations 104/RUs 106 may each include a plurality of antennas. The plurality of antennas may correspond to antenna elements, antenna panels, and/or antenna arrays that may facilitate beamforming operations. For example, the RU 106b transmits a downlink beamformed signal based on a first set of communication beams 132 to the UE 102b in one or more transmit directions of the RU 106b. The UE 102b may receive the downlink beamformed signal based on a second set of communication beams 134b from the RU 106b in one or more receive directions of the UE 102b. In a further example, the UE 102b may also transmit an uplink beamformed signal (e.g., sounding reference signal (SRS) ) to the RU 106b based on the second set of communication beams 134b in one or more transmit directions of the UE 102b. The RU 106b may receive the uplink beamformed signal from the UE 102b in one or more receive directions of the RU 106b.

The UE 102b may perform beam training to determine the best receive and transmit directions for the beamformed signals. The transmit and receive directions for the UEs 102 and the base stations 104/RUs 106 may or may not be the same. In further examples, beamformed signals may be communicated between a first base station/RU 106a and a second base station 104e. For instance, the base station 104e of the cell 190e may transmit a beamformed signal to the RU 106a based on the communication beams 138 in one or more transmit directions of the base station 104e. The RU 106a may receive the beamformed signal from the base station 104e of the cell 190e based on the RU communication beams 136 in one or more receive directions of the RU 106a. In further examples, the base station 104e transmits a downlink beamformed signal to the UE 102e based on the communication beams 138 in one or more transmit directions of the base station 104e. The UE 102e receives the downlink beamformed signal from the base station 104e based on UE communication beams 130 in one or more receive directions of the UE 102e. The UE 102e may also transmit an uplink beamformed signal to the base station 104e based on the UE communication beams 130 in one or more transmit directions of the UE 102e, such that the base station 104e may receive the uplink beamformed signal from the UE 102e in one or more receive directions of the base station 104e.

The base station 104 may include and/or be referred to as a network entity. That is, “network entity” may refer to the base station 104 or at least one unit of the base station 104, such as the RU 106, the DU 108, and/or the CU 110. The base station 104 may also include and/or be referred to as a next generation evolved Node B (ng-eNB) , a next generation NB (gNB) , an evolved NB (eNB) , an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , a TRP, a network node, network equipment, or other related terminology. The base station 104 or an entity at the base station 104 can be implemented as an IAB node, a relay node, a sidelink node, an aggregated (monolithic) base station, or a disaggregated base station including one or more RUs 106, DUs 108, and/or CUs 110. A set of aggregated or disaggregated base stations may be referred to as a next generation-radio access network (NG-RAN) . In some examples, the UE 102a operates in dual connectivity (DC) with the base station 104e and the base station/RU 106a. In such cases, the base station 104e can be a master node and the base station/RU 160a can be a secondary node.

Uplink/downlink signaling may also be communicated via a satellite positioning system (SPS) 114. In an example, the SPS 114 of the cell 190c may be in communication with one or more UEs 102, such as the UE 102c, and one or more base stations 104/RUs 106, such as the RU 106c. The SPS 114 may correspond to one or more of a Global Navigation Satellite System (GNSS) , a global position system (GPS) , a non-terrestrial network (NTN) , or other satellite position/location system. The SPS 114 may be associated with LTE signals, NR signals (e.g., based on round trip time (RTT) and/or multi-RTT) , wireless local area network (WLAN) signals, a terrestrial beacon system (TBS) , sensor-based information, NR enhanced cell ID (NR E-CID) techniques, downlink angle-of-departure (DL-AoD) , downlink time difference of arrival (DL-TDOA) , uplink time difference of arrival (UL-TDOA) , uplink angle-of-arrival (UL-AoA) , and/or other systems, signals, or sensors.

Still referring to FIG. 1, in certain aspects, any of the UEs 102 may include a group-common cell-switching command (GC-CSC) reception component 140 configured to: receive, from a network entity, a cell switching command (CSC) for a UE group, the CSC including an indication for the UE to switch from a source cell to a candidate cell; and perform, with the network entity, a lower-layer triggered mobility (LTM) procedure to switch the UE from the source cell to the candidate cell based on the indication included in the CSC for the UE group.

In certain aspects, any of the base stations 104 or a network entity of the base stations 104 may include a GC-CSC transmission component 150 configured to: transmit, to a UE, a CSC for a UE group that includes the UE, the CSC including an indication to switch the UE from a source cell to a candidate cell; and perform, with the UE, an LTM procedure to switch the UE from the source cell to the candidate cell according to the indication included in the CSC for the UE group.

Accordingly, FIG. 1 describes a wireless communication system that may be implemented in connection with aspects of one or more other figures described herein. Further, although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as 5G-Advanced and future versions, LTE, LTE-advanced (LTE-A) , and other wireless technologies, such as 6G.

FIG. 2 illustrates a diagram 200 of a first base station 104a transmitting a CSC 206 to one or more UEs 102 to switch the one or more UEs 102 from a source cell 204a of the first base station 104a to a target cell 204b of a second base station 104b. A lower-layer triggered mobility (LTM) procedure may be implemented to reduce latency associated with cell-switching/handover procedures for the UEs 102. For example, in comparison to a Layer 3 (L3) cell-switching procedure, which may include increased latency as a result of multiple higher layer message exchanges and reconfiguration, a Layer 1/Layer 2 (L1/L2) cell switching procedure may be based on triggering a configured candidate cell. That is, to perform the LTM procedure, the first base station 104a configures the UE 102 with one or more candidate cell configurations prior to transmitting the CSC 206 to the UE 102. As the UE 102 moves from the source cell 204a toward the target cell 204b, the UE 102 may send beam information to the first base station 104a, which may cause the first base station 104a to trigger a configured candidate cell by transmitting the CSC 206 to the UE 102. The UE 102 receives the CSC 206 and determines which candidate cell configuration to apply. The CSC 206 can carry beam indication and timing advance (TA) information to reduce the latency for switching from the source cell 204a to the target cell 204b.

In cases where multiple UEs 102 are simultaneously moving toward a same target cell 204b, transmitting the CSC 206 to each of the multiple UEs 102 independently may be redundant and/or may result in high signaling overhead. Examples where CSC transmissions may be redundant can include multiple UEs being within a same vehicle traveling along a same road or trajectory, multiple connected mobile devices (e.g., cell phone, smart watch, tablet, etc. ) moving in a same direction, a single UE that is moving with multiple wireless communication equipment included within the single UE, etc. Oftentimes, independent CSC transmissions to such UEs include the same or similar information. Hence, the first base station 104a can reduce signaling overhead with the UEs 102 by transmitting a GC-CSC 206 to the UEs 102. The GC-CSC 206 includes cell switching information applicable to each of the UEs 102, so that the first base station 104a can transmit one CSC transmission to switch the cells for all of the UEs 102.

A TRP, such as the first base station 104a, the second base station 104b, or a network entity thereof, can be associated with or identified by a TRP identifier. For example, the network entity/base station 104 may include or configure a TRP identifier in configurations that the network entity/base station 104 transmits to the UE 102 for uplink or downlink transmissions via a TRP indicated by the TRP identifier. The configurations may correspond to downlink control information (DCI) transmitted on a physical downlink control channel (PDCCH) , a physical downlink shared channel (PDSCH) configuration, a physical uplink control channel (PUCCH) configuration, a physical uplink shared channel (PUSCH) configuration, and/or a channel state information (CSI) resource or SRS configuration included in a radio resource control (RRC) message (e.g., an RRC reconfiguration message or an RRC resume message) that the base station 104 transmits to the UE 102. Downlink transmissions may further include channel state information-reference signal (CSI-RS) transmissions and synchronization signal block (SSB) transmissions.

In other implementations, the base station 104 does not transmit/configure a TRP identifier to the UE 102, but instead uses an implicit indication of the TRP to the UE 102. The implicit indication can be a configuration parameter, such as: a control resource set ECORESET) Poolfndex, a value/candidate of the CORESETPoolfndex, a dataScramblingfdentityPDSCe, a dataScramblingfdentityPDSCe2, or a PrCCe-Resourcedroup. The UE 102 may determine a TRP (identifier) from the implicit indication. The base station 104 can also transmit, to the UE 102, an RRC message (e.g., an RRC reconfiguration message or an RRC resume message) including the configuration parameters.

The first base station 104a may configure or indicate, to the UE 102, a first TRP identifier. Alternatively, the UE 102 may derive the first TRP identifier/value from the implicit indication of the TRP. The first base station 104a may also configure or indicate, to the UE 102, a second TRP identifier/value, or the UE 102 may derive the second TRP identifier/value from the implicit indication. The UE 102 associates the first TRP identifier with the first TRP and the second TRP identifier with the second TRP.

The first base station 104a may configure the serving cell 204a as being associated with the first TRP or the first TRP identifier/value and configure the target cell 204b as being associated with the second TRP or the second TRP identifier/value. The first base station 104a may configure a first CORESET for the serving cell 204a or the first TRP (e.g., CORESETPoolfndex #0 may indicate the first CORESET) . The first base station 104a transmits, to the UE 102, the RRC message (e.g., an RRC setup message, an RRC reconfiguration message, or an RRC resume message) configuring the first CORESET and/or including the CORESETPoolfndex #0. Thus, the UE 102 monitors a PDCCH on the first CORESET to receive DCI from the first base station 104a, which may imply that the UE 102 monitors the PDCCH or receives the DCI via the first TRP. In such cases, the UE 102 determines that CORESETPoolfndex #0 indicates the first TRP.

The second TRP is associated with a non-serving cell, which the first base station 104a may indicate or configure in a second RRC message. The first base station 104a may configure the non-serving cell to be associated with the second TRP or the second TRP identifier/value. The first base station 104 can further configure a second CORESET for the serving cell 204a, the non-serving cell, or the second TRP (e.g., CORESETPoolfndex #1 may indicate the second CORESET) . The RRC message that the first base station 104a transmits to the UE 102 may configure the second CORESET and/or include the CORESETPoolfndex #1. Thus, the UE 102 monitors the PDCCH on the second CORESET to receive DCI, which may imply that the UE 102 monitors the PDCCH or receives the DCI via the second TRP. In such cases, the UE 102 determines that CORESETPoolfndex #1 indicates the second TRP.

The first base station 104a may configure the UEs 102 with one or more candidate cell configurations including information for neighboring cells or non-serving cells of the UEs 102. The one or more candidate cell configurations may include information for the candidate target cell 204b of the UEs 102 for performing the LTM procedure. A candidate cell configuration may correspond to an RRCReconfiguration message, a CelldroupConfig information element (IE) or a SpCellConfig IE. In some examples, the candidate cell is a currently configured/activated secondary cell (SCell) of the UE 102. The candidate cell configuration can include one or more of a candidate cell configuration identifier, a physical cell identifier (PCI) or a logical index of the PCI (e.g., PCI index) , one or more transmission configuration indicator (TCI) state lists for the candidate cell, a configuration for downlink reference signals (e.g., SSB or CSI-RS) for measuring an L1-reference signal received power (L1-RSRP) and/or an L1-signal-to-interfernce plus noise ratio (L1-SINR) for/in the candidate cell, or a configuration for uplink reference signals (e.g., SRS) for measuring uplink CSI for/in the candidate cell.

The first base station 104a may indicate a PDCCH order to the UE 102. The PDCCH order may trigger the UE 102 to perform a random access (RA) procedure. The UE 102 may perform the RA procedure for acquiring the TA value and/or indicating the TA value. The first base station 104a transmits the PDCCH order for the TA value for the candidate cell or target cell 204b. The first base station 104a can transmit the PDCCH order for the TA value for the candidate cell or target cell 204b before transmitting the CSC 206 indicating the candidate cell or target cell 204b. The first base station 104a can also transmit the PDCCH order for the TA value for the neighboring cell or a TRP in a neighboring cell.

The UE 102 transmits a PRACH based on information indicated via the PDCCH order. For the UE 102 to transmit the PRACH, the PDCCH order may indicate one or more of a random access preamble index, an uplink indicator or supplementary uplink indicator that indicates which uplink carrier in the serving cell 204a is for transmitting the PRACH, a synchronization signal/physical broadcast channel (SS/PBCH) index that indicates an SS/PBCH for the UE 102 to determine a random access channel (RACH) occasion for the PRACH transmission, or a PRACH mask index that indicates the RACH occasion associated with the SS/PBCH indicated by the SS/PBCH index for the PRACH transmission. While the CSC 206 illustrated in the diagram 200 may be an independent CSC for an independent UE 102, the CSC 206 may alternatively be a GC-CSC 206, where a single GC-CSC 206 is applicable to all of the multiple UEs 102.

FIG. 3 illustrates a signaling diagram 300 for configuring and implementing a GC-CSC. The UE 102 reports/transmits 306, to the network entity 104, a UE capability for supporting the LTM procedure. The UE 102 may also report/transmit 308, to the network entity 104, a UE capability for supporting the GC-CSC. In some examples, the UE 102 indicates the UE capability for the LTM procedure and the UE capability for the GC-CSC in a same capability message. In other examples, the UE 102 indicates the UE capability for the LTM procedure and the UE capability for the GC-CSC in different capability messages.

The network entity 104 transmits 310, to the UE 102, an RRC configuration enabling the LTM procedure and/or configuring one or more candidate cells. The network entity 104 may also transmit 312, to the UE 102, an RRC configuration enabling the GC-CSC functionality. In some examples, the network entity 104 configures the LTM procedure and/or the one or more candidate cells in a same RRC message as the network entity 104 configures the GC-CSC functionality. In other examples, the network entity 104 configures the LTM procedure and/or the one or more candidate cells in a different RRC message from the RRC message used to configure the GC-CSC functionality.

Based on beam measurement information, the network entity 104 can determine that the UE 102 is moving from a source cell of the network entity 104 to a target cell/neighbor cell configured 310 via the RRC configuration message. The network entity 104 transmits 314, to the UE 102, a GC-CSC indicating that the configured candidate cell is the target cell. After receiving 314, the GC-CSC from the network entity 104, the UE 102 decodes information from the GC-CSC for performing the LTM procedure. In some examples, the GC-CSC is received 314 by both the UE 102 and one or more other UEs (not shown) , as the GC-CSC can also carry information pertaining to the one or more other UEs.

The UE 102 may report/transmit 318, to the network entity 104, acknowledgment/negative acknowledgment (ACK/NACK) feedback for the GC-CSC. The ACK/NACK feedback indicates whether the UE 102 successfully received 314 and decoded 316 the GC-CSC from the network entity 104. In some implementations, the network entity 104 configures whether the UE 102 is to report 318 the ACK/NACK feedback for the GC-CSC. The UE 102 and/or the network entity 104 perform 320 the LTM procedure based on information included in the GC-CSC. In cases where the UE 102 is to report 318 the ACK/NACK feedback to the network entity 104, the UE 102 and the network entity 104 perform 320 the LTM procedure after the ACK/NACK feedback is reported 318. Prior to completing the LTM procedure 320 with the network entity 104, the UE 102 may receive 322 a second CSC from the network entity 104. The second CSC may be a UE-specific CSC or a second GC-CSC, where the previously received/decoded GC-CSC is a first GC-CSC. In either case, the UE 102 may terminate the first LTM procedure 320 with the network entity 104 and perform 324 a second LTM procedure with the network entity 104 based on the second CSC (e.g., second GC-CSC) . In some cases, the UE 102 may not terminate the first LTM procedure 320 with the network entity 104 and perform 324 a second LTM procedure with the network entity 104 based on the second CSC, if the first LTM procedure is triggered by a UE-specific CSC and the second TLM procedure is triggered by a GC-CSC.

In some implementations, the network entity 104 transmits, to the UE 102, a UE-specific CSC via medium access control-control element (MAC-CE) or PDSCH. For example, the CSC may be a MAC-CE. In other implementations, the network entity 104 may indicate, to the UE 102, the UE-specific CSC via DCI. For example, the DCI can schedule a PDSCH that carries the UE-specific CSC. The CSC may indicate a target cell or a candidate cell as well as a candidate cell configuration identifier. “Target cell” may be, or can refer to, a candidate cell indicated via the CSC.

After receiving the CSC, or after an action time of the CSC, the UE 102 performs 320 the LTM procedure with the network entity 104 based on the CSC. The UE 102 may determine the target cell and/or a corresponding configuration based on the candidate cell configuration identifier indicated in the CSC. After completion of the LTM procedure, the target cell indicated by the CSC may become a (next or current) physical serving cell/PCell. The UE 102 can then move from the source cell to the target cell, where the UE 102 can receive downlink data and/or transmit uplink data in the target cell. “Source cell” may be, or can refer to, an initial/previous physical serving cell/PCell of the UE 102 prior to receiving the CSC and completing LTM procedure.

The CSC may include one or more fields or information, such as information for identifying target cells, TA-related information, a beam indication for the target cell, active downlink/uplink bandwidth parts (BWPs) for the target cell or candidate cell, etc. The beam indication may be a joint unified TCI state/index or a pair of uplink and downlink unified TCI states/indexes. In further examples, the CSC indicates triggering information, such as instructions to trigger an aperiodic tracking reference signal (TRS) transmitted from the target cell, where the aperiodic TRS may be quasi-co-located (QCLed) with a downlink reference signal configured in beam indication signaling for the target cell, if the beam indication signaling for the target cell is included in the CSC. Other triggering information can include instructions to trigger CSI acquisition of the target cell and a corresponding report to target cell, instructions to trigger an aperiodic CSI-RS for pathloss measurement for uplink power control where the aperiodic CSI-RS may be QCLed with a downlink reference signal configured in the beam indication signaling for the target cell if the beam indication signaling for the target cell is included in the CSC, instructions to trigger an aperiodic SRS transmission to the target cell, and/or a cell-radio network temporary identifier (C-RNTI) .

In further implementations, the network entity 104 transmits 314, to the UE 102, the GC-CSC via MAC-CE or PDSCH. For example, the GC-CSC may be a MAC-CE. In other implementations, network entity 104 may indicate, to the UE 102, the GC-CSC via DCI. For example, the DCI can schedule a PDSCH that carries the GC-CSC. One or more UEs, including the UE 102, may be able to receive 314 and decode/apply the GC-CSC. Similarly, one or more UEs, including the UE 102, can trigger or perform 320 the LTM procedure based on receiving 314 the GC-CSC from the network entity 104. After receiving 314 the GC-CSC, or after an action time of the GC-CSC, the one or more UE (s) may perform 320 the LTM procedure with the network entity 104 based on the GC-CSC. The one or more UE (s) may determine the target cell and/or a corresponding configuration based on the candidate cell configuration identifier indicated in the GC-CSC. In still further implementations, the network entity 104 transmits 314, to the UE 102, the CSC (e.g., GC-CSC) in DCI. The contents of the GC-CSC can be indicated as one or more DCI fields in the DCI. The DCI may not be an uplink grant or a downlink assignment.

If the network entity 104 transmits 314 the GC-CSC to a group of UEs, including the UE 102, for triggering the LTM procedure, the group of UEs, including the UE 102, may perform 320 the LTM procedure with the network entity 104 at a same time. Some or all of the contents of the GC-CSC may be applied to the entire group of UEs. The GC-CSC may have one or more fields (e.g., DCI fields or MAC-CE fields) that include or indicate information, such as information for identifying target cells, TA-related information, a beam indication for the target cell, active downlink/uplink BWPs for the target cell or candidate cell, etc. The beam indication may be a joint beam indication or a pair of uplink and downlink unified TCI states/indexes. In further examples, the CSC indicates triggering information, such as instructions to trigger an aperiodic TRS transmitted from the target cell, where the aperiodic TRS may be QCLed with a downlink reference signal configured in beam indication signaling for the target cell, if the beam indication signaling for the target cell is included in the CSC. Other triggering information can include instructions to trigger CSI acquisition of the target cell and a corresponding report to target cell, instructions to trigger an aperiodic CSI-RS for pathloss measurement for uplink power control where the aperiodic CSI-RS may be QCLed with a downlink reference signal configured in the beam indication signaling for the target cell if the beam indication signaling for the target cell is included in the CSC, instructions to trigger an aperiodic SRS transmission to the target cell, and/or indexes to derive a PUCCH resource for the ACK/NACK feedback. Some or all of the DCI or MAC-CE fields may be shared or applied by the group of UEs for triggering or performing 320 the LTM procedure with the network entity 104.

The network entity 104 may include configuration identifier values in candidate cell configurations that associate/indicate the same PCI or PCI index for each UE of the group of UEs. The network entity 104 may indicate/configure TCI state list (s) configured for target cells of the group of UEs, where a TCI state with the same TCI state identifier includes a same QCL source reference signal or reference signal identifier. The network entity 104 may indicate a BWP configuration for the group of UEs. The BWP configuration may include same or different BWP identifiers for the group of UEs. The BWP configuration may be included in a same RRC parameters setting. One UE (e.g., the UE 102) of the group of UEs may perform the RA procedure for acquiring the TA value for the LTM procedure before receiving 314 the GC-CSC from the network entity 104. The one UE (e.g., the UE 102) may receive a PDCCH order for acquiring the TA value for the LTM procedure. The TA value acquired from the RA procedure initiated by the PDCCH order may be indicated/included in the GC-CSC. The TA value acquired from the RA procedure initiated by the PDCCH order may be applied or shared by the group of UEs.

In some implementations, the GC-CSC is divided into a number of subsections. Each subsection/portion of the GC-CSC can be applied to each UE in the group of UEs. The subsection/portion of the GC-CSC may have one or more MAC-CE fields that include or indicate information similar to the one or more fields or information described above. The UE capability message that the UE 102 transmits 308 to the network entity 104 may indicate whether the UE 102 supports the GC-CSC not being divided into subsections/portions. That is, the GC-CSC may indicate one candidate cell configuration identifier and corresponding information. The UE capability message may further indicate that the GC-CSC can include a number of subsections/portions and/or a maximum number of subsections/portions that can be included in the GC-CSC. The GC-CSC can either include either no subsection or a number of subsections. Based on the UE capability, the network entity 104 may configure 312 the GC-CSC to not be divided into subsections, the GC-CSC to be divided into a number of subsections, and/or the maximum number of subsections that the GC-CSC may be divided into.

The GC-CSC may be carried in a PDSCH scheduled via DCI or the GC-CSC may be a DCI. The DCI may be of DCI format 1_0, DCI format 0_0, or DCI format 2_N, where N is an integer greater than 0. The network entity 104 transmits the DCI in a dedicated search space set configured through the RRC signaling. For example, the network entity 104 transmits the DCI in a search space set dedicated for the LTM procedure, a CSC procedure, or a GC-CSC procedure. The network entity 104 can configure a group-common radio network temporary identifier (RNTI) for the group of UEs, including the UE 102. The group-common RNTI may be for scrambling or descrambling the GC-CSC (e.g., the DCI or MAC-CE) and/or the PDSCH carrying the GC-CSC. In examples, the UE may determine a cyclic redundancy check (CRC) code for the PDCCH based on the group-common RNTI, where the CRC code is scrambled by the group-common RNTI. The group-common RNTI may be also indicated, updated, or activated/deactivated a MAC-CE. A downlink assignment or a downlink grant (e.g., for a time and frequency resource, a modulation and coding scheme (MCS) , etc. ) for the PDSCH carrying the GC-CSC may be configured by the RRC signaling. The network entity 104 may configure a periodicity and slot offset for a candidate PDSCH carrying the GC-CSC through the RRC signaling.

The network entity 104 may configure the group of UEs, including the UE 102, to report 318 ACK/NACK feedback for the GC-CSC, which may imply reporting ACK/NACK feedback for group-common DCI or PDCCH. After receiving/decoding the GC-CSC or the DCI, one or more UEs of the group of UEs may report 318 the ACK/NACK feedback for the GC-CSC, and one or more other UEs of the group of UEs may refrain from reporting the ACK/NACK feedback for the GC-CSC. The UE 102 may determine a PUCCH resource for reporting 318 ACK/NACK for the GC-CSC based on a PUCCH resource indicator (PRI) field in a UE-specific DCI or one or more MAC-CE fields in the GC-CSC. The UE 102 may determine the PUCCH resource for reporting 318 ACK/NACK for the GC-CSC based on a preconfigured or pre-indicated PUCCH resource by the network entity 104. In some examples, the UE 102 determines the PUCCH resource for reporting 318 ACK/NACK for the GC-CSC based on a rule-based procedure (e.g., a PUCCH resource with a lowest PUCCH resource identifier) . The one or more the UEs may transmit an uplink signal, such as a PUCCH via a PUCCH resource, configured or indicated by the network entity 104 through RRC signaling, MAC-CE (e.g., CSC) , or DCI (e.g., the DCI scheduling the PDSCH with CSC or the DCI itself being the CSC) , if the one or more UEs fail to decode 316 the CSC. If the network entity 104 detects the uplink signal, the network entity 104 may schedule a retransmission of the GC-CSC or at least the subsection/portion of the GC-CSC corresponding to the one or more UEs. In some implementations, the network entity 102 may indicate whether the GC-CSC is a new transmission or retransmission by the DCI with GC-CSC or DCI scheduling the PDSCH with MAC-CE for GC-CSC or MAC-CE for the GC-CSC.

In further implementations, the UE capability message may indicate one or more of whether the UE 102 may receive/decode a UE-specific CSC, whether the UE 102 may receive/decode a GC-CSC (e.g., as a MAC-CE or DCI) , or whether the UE 102 may receive/decode a combination of UE-specific and group-common CSCs. The network entity 104 may configure 312 such CSC functionality to the UE 102 (e.g., based on the UE capability message) via RRC signaling.

The UE 102 may perform 320 the LTM procedure after receiving 314 a GC-CSC or after receiving a UE-specific CSC. In some examples, regardless of the type of CSC that triggers the LTM procedure 320, the UE 102 may receive 322 a second CSC (e.g., a GC-CSC or a UE-specific CSC) before the UE 102 completes the LTM procedure 320 with the network entity 104. Hence, the UE 102 may terminate the ongoing LTM procedure 320 upon receiving 322 the second CSC from the network entity 104 and may apply the content indicated in the second CSC. For example, the UE 102 may perform 324 a second LTM procedure with the network entity 104 based on the second CSC. In some implementations, if the ongoing LTM procedure 320 is triggered by a UE-specific CSC and the second LTM procedure 324 is triggered by a GC-CSC, the UE 102 may continue performing 320 the ongoing LTM procedure 320 with the network entity 104, despite receiving 322 the second/ (GC-) CSC, as a first priority of a UE-specific CSC may be higher than a second priority of a GC-CSC.

Completion of the LTM procedure may include/refer to the UE 102 transmitting an RRC complete message, or handover complete message, to the target cell indicated by the CSC that triggered the LTM procedure. After receiving 314 a CSC indicating the target cell and/or triggering the LTM procedure, the UE 102 may complete a RA procedure for the target cell, a RA procedure with a RA preamble transmitted to the target cell, or a RA procedure associated with, or performed by, an SSB or CSI-RS from the target cell. For completion of the LTM procedure, the UE 102 may determine that the network entity 104 has successfully received/decoded (first) uplink data from the UE to/in the target cell.

The network entity 104 may or may not transmit the UE-specific CSC and the GC-CSC in a same slot or same span. For example, the network entity 104 may or may not transmit DCI that schedules a PDSCH carrying UE-specific CSC and DCI that schedules a PDSCH carrying GC-CSC in the same slot or same span. The UE 102 may similarly not expect to receive a UE-specific CSC and a GC-CSC from the network entity 104 in the same slot or same span. If the UE 102 receives a UE-specific CSC and a GC-CSC in the same slot or same span, the UE 102 may identify the reception (s) as an error. That is, the UE 102 may discard or ignore one or both of the UE-specific CSC and the GC-CSC. For example, the UE 102 can process one of the UE-specific CSC or the GC-CSC and discard or ignore the other one of the UE-specific CSC or the GC-CSC.

The UE capability message may indicate whether the UE supports receiving a UE-specific CSC and a GC-CSC in the same slot or same span. In some implementations, the UE capability message indicates that the UE 102 does not support receiving UE-specific CSC and GC-CSC in the same slot or same span. In other implementations, the UE capability message indicates that the UE 102 does support receiving UE-specific CSC and GC-CSC in the same slot or same span. If the UE 102 receives, and supports receiving, a UE-specific CSC and a GC-CSC in the same slot or same span, the UE 102 may apply one of the UE-specific CSC or the GC-CSC based on pre-configured or pre-determined protocols. For instance, the UE 102 may apply the UE-specific CSC (e.g., based on the UE-specific CSC having a higher priority than the GC-CSC) . Alternatively, the UE 102 may determine to apply the GC-CSC.

In some examples, the UE 102 may receive a UE-specific CSC and a GC-CSC in the same slot or same span that indicates same content/information for the UE 102. Accordingly, the UE 102 may apply the content/information. However, if the UE 102 receives a UE-specific CSC and a GC-CSC in the same slot or same span that indicates different content/information for the UE 102, the UE 102 may regard the reception (s) as an error. For example, the UE 102 may discard or ignore one or both of the UE-specific CSC or the GC-CSC. FIGs. 2-3 illustrate LTM procedures based on CSCs. FIGs. 4-5 show methods for implementing one or more aspects of FIGs. 2-3. In particular, FIG. 4 shows an implementation by the UE 102 of the one or more aspects of FIGs. 2-3. FIG. 5 shows an implementation by the network entity 104 of the one or more aspects of FIGs. 2-3.

FIG. 4 illustrates a flowchart 400 of a method of wireless communication at a UE. With reference to FIGs. 1-3 and 6, the method may be performed by the UE 102, the UE apparatus 602, etc., which may include the memory 626′, 606′, 616, and which may correspond to the entire UE 102 or the entire UE apparatus 602, or a component of the UE 102 or the UE apparatus 602, such as the wireless baseband processor 626 and/or the application processor 606.

The UE 102 transmits 408, to a network entity, a UE capability message indicating a capability of a UE for performing an LTM procedure based on a CSC for a UE group. For example, referring to FIG. 3, the UE 102 transmits 308, to the network entity 104, a UE capability for supporting GC-CSC. The UE 102 may also transmit 306, to the network entity 104, a UE capability for supporting the LTM procedure.

The UE 102 receives 412, from the network entity, a configuration enabling the UE to perform the LTM procedure based on the CSC for the UE group. For example, referring to FIG. 3, the UE 102 receives 312, from the network entity 104, an RRC configuration enabling GC-CSC functionality. The UE 102 may also receive 310 an RRC configuration enabling the LTM procedure and/or configuring one or more candidate cells.

The UE 102 receives 414, from the network entity, the CSC for the UE group, the UE being a member of the UE group-the CSC includes an indication for the UE to switch from a source cell to a candidate cell. For example, referring to FIG. 3, the UE 102 receives 314, from the network entity 104, a GC-CSC indicating a configured candidate cell as the target cell.

The UE 102 decodes 416 the CSC for the UE group. For example, referring to FIG. 3, the UE 102 decodes 316 information from the GC-CSC for performing the LTM procedure.

The UE 102 transmits 418, to the network entity on a PUCCH resource, ACK/NACK feedback for the CSC for the UE group. For example, referring to FIG. 3, the UE 102 transmits 318, to the network entity 104, ACK/NACK feedback for the GC-CSC.

The UE 102 performs 420, with the network entity, the LTM procedure to switch the UE from the source cell to the candidate cell based on the indication included in the CSC for the UE group. For example, referring to FIG. 3, the UE 102 performs 320, with the network entity 104, the LTM procedure based on information from the GC-CSC.

The UE 102 receives 422, from the network entity, a second CSC prior to completing the LTM procedure with the network entity-the second CSC triggers termination of the LTM procedure. For example, referring to FIG. 3, the UE 102 receives 322, from the network entity 104, a second CSC, which may be a GC-CSC or a UE-specific CSC.

The UE 102 performs 424, with the network entity, a second LTM procedure based on the second CSC. For example, referring to FIG. 3, the UE 102 performs 324, with the network entity 104, a second LTM procedure based on the second CSC that may be a GC-CSC or a UE-specific CSC. FIG. 4 describes a method from a UE- side of a wireless communication link, whereas FIG. 5 describes a method from a network-side of the wireless communication link.

FIG. 5 is a flowchart 500 of a method of wireless communication at a network entity. With reference to FIGs. 1-3 and 7, the method may be performed by one or more network entities 104, which may correspond to a base station or a unit of the base station, such as the RU 106, the DU 108, the CU 110, an RU processor 706, a DU processor 726, a CU processor 746, etc. The one or more network entities 104 may include memory 706'/726'/746', which may correspond to an entirety of the one or more network entities 104, or a component of the one or more network entities 104, such as the RU processor 706, the DU processor 726, or the CU processor 746.

The network entity 104 receives 508, from a UE, a UE capability message indicating a capability of the UE for performing an LTM procedure based on a CSC for a UE group. For example, referring to FIG. 3, the network entity 104 receives 308, from the UE 102, a UE capability for supporting GC-CSC. The network entity 104 may also receive 306, from the UE 102, a UE capability for supporting the LTM procedure.

The network entity 104 transmits 512, to the UE, a configuration enabling the UE to perform the LTM procedure based on the CSC for the UE group. For example, referring to FIG. 3, the network entity 104 transmits 312, to the UE 102, an RRC configuration enabling GC-CSC functionality. The network entity 104 may also transmit 310 an RRC configuration enabling the LTM procedure and/or configuring one or more candidate cells.

The network entity 104 transmits 514, to the UE, the CSC for the UE group that includes the UE-the CSC includes an indication to switch the UE from a source cell to a candidate cell. For example, referring to FIG. 3, the network entity 104 transmits 314, to the UE 102, a GC-CSC indicating a configured candidate cell as the target cell.

The network entity 104 receives 518, from the UE on a PUCCH resource, ACK/NACK feedback for the CSC for the UE group. For example, referring to FIG. 3, the network entity 104 receives 318, from the UE 102, ACK/NACK feedback for the GC-CSC.

The network entity 104 performs 520, with the UE, the LTM procedure to switch the UE from the source cell to the candidate cell according to the indication included in the CSC for the UE group. For example, referring to FIG. 3, the network entity 104 performs 320, with the UE 102, the LTM procedure based on information in the GC-CSC.

The network entity 104 transmits 522, to the UE, a second CSC prior to completing the LTM procedure with the UE-the second CSC triggers termination of the LTM procedure. For example, referring to FIG. 3, the network entity 104 transmits 322, to the UE 102, a second CSC, which may be a GC-CSC or a UE-specific CSC.

The network entity 104 performs 524, with the UE, a second LTM procedure based on the second CSC. For example, referring to FIG. 3, the network entity 104 performs 324, with the UE 102, a second LTM procedure based on the second CSC that may be a GC-CSC or a UE-specific CSC. A UE apparatus 602, as described in FIG. 6, may perform the method of flowchart 400. The one or more network entities 104, as described in FIG. 7, may perform the method of flowchart 500.

FIG. 6 is a diagram 600 illustrating an example of a hardware implementation for a UE apparatus 602. The UE apparatus 602 may be the UE 102, a component of the UE 102, or may implement UE functionality. The UE apparatus 602 may include an application processor 606, which may have on-chip memory 606'. In examples, the application processor 606 may be coupled to a secure digital (SD) card 608 and/or a display 610. The application processor 606 may also be coupled to a sensor (s) module 612, a power supply 614, an additional module of memory 616, a camera 618, and/or other related components. For example, the sensor (s) module 612 may control a barometric pressure sensor/altimeter, a motion sensor such as an inertial management unit (IMU) , a gyroscope, accelerometer (s) , a light detection and ranging (LIDAR) device, a radio-assisted detection and ranging (RADAR) device, a sound navigation and ranging (SONAR) device, a magnetometer, an audio device, and/or other technologies used for positioning.

The UE apparatus 602 may further include a wireless baseband processor 626, which may be referred to as a modem. The wireless baseband processor 626 may have on-chip memory 626′. Along with, and similar to, the application processor 606, the wireless baseband processor 626 may also be coupled to the sensor (s) module 612, the power supply 614, the additional module of memory 616, the camera 618, and/or other related components. The wireless baseband processor 626 may be additionally coupled to one or more subscriber identity module (SIM) card (s) 620 and/or one or more transceivers 630 (e.g., wireless RF transceivers) .

Within the one or more transceivers 630, the UE apparatus 602 may include a Bluetooth module 632, a WLAN module 634, an SPS module 636 (e.g., GNSS module) , and/or a cellular module 638. The Bluetooth module 632, the WLAN module 634, the SPS module 636, and the cellular module 638 may each include an on-chip transceiver (TRX) , or in some cases, just a transmitter (TX) or just a receiver (RX) . The Bluetooth module 632, the WLAN module 634, the SPS module 636, and the cellular module 638 may each include dedicated antennas and/or utilize antennas 640 for communication with one or more other nodes. For example, the UE apparatus 602 can communicate through the transceiver (s) 630 via the antennas 640 with another UE (e.g., sidelink communication) and/or with a network entity 104 (e.g., uplink/downlink communication) , where the network entity 104 may correspond to a base station or a unit of the base station, such as the RU 106, the DU 108, or the CU 110.

The wireless baseband processor 626 and the application processor 606 may each include a computer-readable medium /memory 626′, 606′, respectively. The additional module of memory 616 may also be considered a computer-readable medium /memory. Each computer-readable medium /memory 626′, 606′, 616 may be non-transitory. The wireless baseband processor 626 and the application processor 606 may each be responsible for general processing, including execution of software stored on the computer-readable medium /memory 626′, 606′, 616. The software, when executed by the wireless baseband processor 626 /application processor 606, causes the wireless baseband processor 626 /application processor 606 to perform the various functions described herein. The computer-readable medium /memory may also be used for storing data that is manipulated by the wireless baseband processor 626 /application processor 606 when executing the software. The wireless baseband processor 626 /application processor 606 may be a component of the UE 102. The UE apparatus 602 may be a processor chip (e.g., modem and/or application) and include just the wireless baseband processor 626 and/or the application processor 606. In other examples, the UE apparatus 602 may be the entire UE 102 and include the additional modules of the apparatus 602.

As discussed in FIG. 1 and implemented with respect to FIG. 4, the GC-CSC reception component 140 is configured to: receive, from a network entity, a CSC for a UE group, the CSC including an indication for the UE to switch from a source cell to a candidate cell; and perform, with the network entity, an LTM procedure to switch the UE from the source cell to the candidate cell based on the indication included in the CSC for the UE group. The GC-CSC reception component 140 may be within the application processor 606 (e.g., at 140a) , the wireless baseband processor 626 (e.g., at 140b) , or both the application processor 606 and the wireless baseband processor 626. The GC-CSC reception component 140a-140b may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by one or more processors configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by the one or more processors, or a combination thereof.

FIG. 7 is a diagram 700 illustrating an example of a hardware implementation for one or more network entities 104. The one or more network entities 104 may be a base station, a component of a base station, or may implement base station functionality. The one or more network entities 104 may include, or may correspond to, at least one of the RU 106, the DU, 108, or the CU 110. The CU 110 may include a CU processor 746, which may have on-chip memory 746′. In some aspects, the CU 110 may further include an additional module of memory 756 and/or a communications interface 748, both of which may be coupled to the CU processor 746. The CU 110 can communicate with the DU 108 through a midhaul link 162, such as an F1 interface between the communications interface 748 of the CU 110 and a communications interface 728 of the DU 108.

The DU 108 may include a DU processor 726, which may have on-chip memory 726′. In some aspects, the DU 108 may further include an additional module of memory 736 and/or the communications interface 728, both of which may be coupled to the DU processor 726. The DU 108 can communicate with the RU 106 through a fronthaul link 160 between the communications interface 728 of the DU 108 and a communications interface 708 of the RU 106.

The RU 106 may include an RU processor 706, which may have on-chip memory 706′. In some aspects, the RU 106 may further include an additional module of memory 716, the communications interface 708, and one or more transceivers 730, all of which may be coupled to the RU processor 706. The RU 106 may further include antennas 740, which may be coupled to the one or more transceivers 730, such that the RU 106 can communicate through the one or more transceivers 730 via the antennas 740 with the UE 102.

The on-chip memory 706′, 726′, 746′and the additional modules of memory 716, 736, 756 may each be considered a computer-readable medium /memory. Each computer-readable medium /memory may be non-transitory. Each of the processors 706, 726, 746 is responsible for general processing, including execution of software stored on the computer-readable medium /memory. The software, when executed by the corresponding processor (s) 706, 726, 746 causes the processor (s) 706, 726, 746 to perform the various functions described herein. The computer-readable medium /memory may also be used for storing data that is manipulated by the processor (s) 706, 726, 746 when executing the software. In examples, the GC-CSC transmission component 150 may sit at any of the one or more network entities 104, such as at the CU 110; both the CU 110 and the DU 108; each of the CU 110, the DU 108, and the RU 106; the DU 108; both the DU 108 and the RU 106; or the RU 106.

As discussed in FIG. 1 and implemented with respect to FIG. 5, the GC-CSC transmission component 150 is configured to: transmit, to a UE, a CSC for a UE group that includes the UE, the CSC including an indication to switch the UE from a source cell to a candidate cell; and perform, with the UE, an LTM procedure to switch the UE from the source cell to the candidate cell according to the indication included in the CSC for the UE group. The GC-CSC transmission component 150 may be within one or more processors of the one or more network entities 104, such as the RU processor 706 (e.g., at 150a) , the DU processor 726 (e.g., at 150b) , and/or the CU processor 746 (e.g., at 150c) . The GC-CSC transmission component 150a-150c may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by one or more processors 706, 726, 746 configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by the one or more processors 706, 726, 746, or a combination thereof.

The specific order or hierarchy of blocks in the processes and flowcharts disclosed herein is an illustration of example approaches. Hence, the specific order or hierarchy of blocks in the processes and flowcharts may be rearranged. Some blocks may also be combined or deleted. Dashed lines may indicate optional elements of the diagrams. The accompanying method claims present elements of the various blocks in an example order, and are not limited to the specific order or hierarchy presented in the claims, processes, and flowcharts.

The detailed description set forth herein describes various configurations in connection with the drawings and does not represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough explanation of various concepts. However, these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Aspects of wireless communication systems, such as telecommunication systems, are presented with reference to various apparatuses and methods. These apparatuses and methods are described in the following detailed description and are illustrated in the accompanying drawings by various blocks, components, circuits, processes, call flows, systems, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

An element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs) , central processing units (CPUs) , application processors, digital signal processors (DSPs) , reduced instruction set computing (RISC) processors, systems-on-chip (SoC) , baseband processors, field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other similar hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software, which may be referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, or any combination thereof.

If the functionality described herein is implemented in software, the functions may be stored on, or encoded as, one or more instructions or code on a computer-readable medium, such as a non-transitory computer-readable storage medium. Computer- readable media includes computer storage media and can include a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of these types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer. Storage media may be any available media that can be accessed by a computer.

Aspects, implementations, and/or use cases described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, the aspects, implementations, and/or use cases may come about via integrated chip implementations and other non-module-component based devices, such as end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, artificial intelligence (AI) -enabled devices, machine learning (ML) -enabled devices, etc. The aspects, implementations, and/or use cases may range from chip-level or modular components to non-modular or non-chip-level implementations, and further to aggregate, distributed, or original equipment manufacturer (OEM) devices or systems incorporating one or more techniques described herein.

Devices incorporating the aspects and features described herein may also include additional components and features for the implementation and practice of the claimed and described aspects and features. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes, such as hardware components, antennas, RF-chains, power amplifiers, modulators, buffers, processor (s) , interleavers, adders/summers, etc. Techniques described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, aggregated or disaggregated components, end-user devices, etc., of varying configurations.

The description herein is provided to enable a person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not limited to the aspects described herein, but are to be interpreted in view of the full scope of the present disclosure consistent with the language of the claims.

Reference to an element in the singular does not mean “one and only one” unless specifically stated, but rather “one or more. ” Terms such as “if, ” “when, ” and “while” do not imply an immediate temporal relationship or reaction. That is, these phrases, e.g., “when, ” do not imply an immediate action in response to or during the occurrence of an action, but simply imply that if a condition is met then an action will occur, but without requiring a specific or immediate time constraint for the action to occur. The terms “may” , “might” , and “can” , as used in this disclosure, often carry certain connotations. For example, “may” refers to a permissible feature that may or may not occur, “might” refers to a feature that probably occurs, and “can” refers to a capability (e.g., capable of) . The phrase “For example” often carries a similar connotation to “may” and, therefore, “may” is sometimes excluded from sentences that include “for example” or other similar phrases.

Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C” or “one or more of A, B, or C” include any combination of A, B, and/or C, such as A and B, A and C, B and C, or A and B and C, and may include multiples of A, multiples of B, and/or multiples of C, or may include A only, B only, or C only. Sets should be interpreted as a set of elements where the elements number one or more.

Unless otherwise specifically indicated, ordinal terms such as “first” and “second” do not necessarily imply an order in time, sequence, numerical value, etc., but are used to distinguish between different instances of a term or phrase that follows each ordinal term. Reference numbers, as used in the specification and figures, are sometimes cross-referenced among drawings to denote same or similar features. A feature that is exactly the same in multiple drawings may be labeled with the same reference number in the multiple drawings. A feature that is similar among the multiple drawings, but not exactly the same, may be labeled with reference numbers that have different leading numbers, but have one or more of the same trailing numbers (e.g., 206, 306, 406, etc., may refer to similar features in the drawings) . Sometimes an “X” is used to universally denote multiple variations of a feature. For instance, “X06” can universally refer to all reference numbers that end in “06” (e.g., 206, 306, 406, etc. ) .

Structural and functional equivalents to elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are encompassed by the claims. The words “module, ” “mechanism, ” “element, ” “device, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ” As used herein, the phrase “based on” shall not be construed as a reference to a closed set of information, one or more conditions, one or more factors, or the like. In other words, the phrase “based on A” , where “A” may be information, a condition, a factor, or the like, shall be construed as “based at least on A” unless specifically recited differently.

The following examples are illustrative only and may be combined with other examples or teachings described herein, without limitation.

Example 1 is a method of wireless communication at a UE, including: receiving, from a network entity, a CSC for a UE group, the CSC including an indication for the UE to switch from a source cell to a candidate cell; and performing, with the network entity, an LTM procedure to switch the UE from the source cell to the candidate cell based on the indication included in the CSC for the UE group.

Example 2 may be combined with Example 1 and includes that the CSC includes common information for the UE group for switching all UEs of the UE group to the candidate cell based on the common information.

Example 3 may be combined with Example 1 and includes that the indication includes a first portion dedicated to the UE and a second portion dedicated to a different UE of the UE group, the UE being switched from the source cell to the candidate cell based on the first portion.

Example 4 may be combined with any of Examples 1-3 and includes that the CSC for the UE group includes at least one of: a first identifier of the candidate cell, a second identifier of a portion of the indication dedicated to the UE, TA information, beam indication information for the candidate cell, or a BWP for the candidate cell.

Example 5 may be combined with any of Examples 1-4 and includes that the CSC for the UE group includes a MAC-CE.

Example 6 may be combined with any of Examples 1-4 and includes that the CSC for the UE group includes DCI.

Example 7 may be combined with any of Examples 1-6 and further includes decoding the CSC for the UE group based on at least one of: a RNTI for the UE group, a dedicated search space set, a dedicated CORESET, or a DCI format type.

Example 8 may be combined with any of Examples 1-7 and further includes transmitting, to the network entity on a PUCCH resource, ACK/NACK feedback for the CSC associated with the UE group.

Example 9 may be combined with any of Examples 1-7 and further includes receiving, from the network entity, a second CSC prior to completing the LTM procedure with the network entity, the second CSC triggering termination of the LTM procedure; and performing, with the network entity, a second LTM procedure based on the second CSC.

Example 10 may be combined with any of Examples 1-9 and further includes transmitting, to the network entity, a UE capability message indicating a capability of the UE for the performing the LTM procedure based on the CSC for the UE group.

Example 11 may be combined with any of Examples 1-10 and further includes receiving, from the network entity, a configuration enabling the UE to perform the LTM procedure based on the CSC for the UE group.

Example 12 is a method of wireless communication at a network entity, including: transmitting, to a UE, a CSC for a UE group that includes the UE, the CSC including an indication to switch the UE from a source cell to a candidate cell; and performing, with the UE, an LTM procedure to switch the UE from the source cell to the candidate cell according to the indication included in the CSC for the UE group.

Example 13 may be combined with Example 12 and includes that the CSC includes common information for the UE group for switching all UEs of the UE group to the candidate cell based on the common information.

Example 14 may be combined with Example 12 and includes that the indication includes a first portion dedicated to the UE and a second portion dedicated to a different UE of the UE group, the switching of the UE from the source cell to the candidate cell being based on the first portion.

Example 15 may be combined with any of Examples 12-14 and includes that the CSC for the UE group includes at least one of: a first identifier of the candidate cell, a second identifier of a portion of the indication, TA information, beam indication information for the candidate cell, or a BWP for the candidate cell.

Example 16 may be combined with any of Examples 12-15 and includes that the CSC for the UE group includes a MAC-CE.

Example 17 may be combined with any of Examples 12-15 and includes that the CSC for the UE group includes DCI.

Example 18 may be combined with any of Examples 12-17 and further includes receiving, from the UE on a PUCCH resource, ACK/NACK feedback for the CSC associated with the UE group.

Example 19 may be combined with any of Examples 12-18 and further includes transmitting, to the UE, a second CSC prior to completing the LTM procedure with the UE, the transmitting the second CSC triggering termination of the LTM procedure; and performing, with the UE, a second LTM procedure based on the second CSC.

Example 20 may be combined with any of Examples 12-19 and further includes receiving, from the UE, a UE capability message indicating a capability of the UE for performing the LTM procedure based on the CSC for the UE group.

Example 21 may be combined with any of Examples 12-20 and further includes transmitting, to the UE, a configuration enabling the UE to perform the LTM procedure based on the CSC for the UE group.

Example 22 is an apparatus for wireless communication for implementing a method as in any of Examples 1-21.

Example 23 is an apparatus for wireless communication including means for implementing a method as in any of Examples 1-21.

Example 24 is a non-transitory computer-readable medium storing computer executable code, the code when executed by a processor causes the processor to implement a method as in any of Examples 1-21.

Claims

A method of wireless communication at a user equipment (UE) (102) , comprising:

receiving (314) , from a network entity (104) , a cell switching command (CSC) for a UE group, the CSC including an indication for the UE (102) to switch from a source cell (204a) to a candidate cell (204b) ; and

performing (320) , with the network entity (104) , a lower-layer triggered mobility (LTM) procedure to switch the UE (102) from the source cell (204a) to the candidate cell (204b) based on the indication included in the CSC for the UE group.
The method of claim 1, wherein the CSC includes common information for the UE group for switching all UEs of the UE group to the candidate cell (204a) based on the common information.
The method of claim 1, wherein the indication includes a first portion dedicated to the UE (102) and a second portion dedicated to a different UE of the UE group, the UE (102) being switched from the source cell (204a) to the candidate cell (204b) based on the first portion.
The method of any of claims 1-3, wherein the CSC for the UE group includes at least one of:

a first identifier of the candidate cell (204b) ,

a second identifier of a portion of the indication dedicated to the UE (102) ,

timing advance (TA) information,

beam indication information for the candidate cell (204b) , or

a bandwidth part (BWP) for the candidate cell (204b) .
The method of any of claims 1-4, wherein the CSC for the UE group includes a medium access control-control element (MAC-CE) .
The method of any of claims 1-4, wherein the CSC for the UE group includes downlink control information (DCI) .
The method of any of claims 1-6, further comprising:

decoding (316) the CSC for the UE group based on at least one of:

a radio network temporary identifier (RNTI) for the UE group,

a dedicated search space set,

a dedicated control resource set (CORESET) , or

a DCI format type.
The method of any of claims 1-7, further comprising:

transmitting (318) , to the network entity (104) on a physical uplink control channel (PUCCH) resource, acknowledgment/negative acknowledgment (ACK/NACK) feedback for the CSC associated with the UE group.
The method of any of claims 1-8, further comprising:

receiving (322) , from the network entity (104) , a second CSC prior to completing the LTM procedure (320) with the network entity (104) , the second CSC triggering termination of the LTM procedure; and

performing (324) , with the network entity (104) , a second LTM procedure based on the second CSC.
The method of any of claims 1-9, further comprising:

transmitting (306) , to the network entity (104) , a UE capability message indicating a capability of the UE (102) for the performing (320) the LTM procedure based on the CSC for the UE group.
The method of any of claims 1-10, further comprising:

receiving (312) , from the network entity (104) , a configuration enabling the UE (102) to perform (320) the LTM procedure based on the CSC for the UE group.
A method of wireless communication at a network entity (104) , comprising:

transmitting (314) , to a user equipment (UE) (102) , a cell switching command (CSC) for a UE group that includes the UE (102) , the CSC including an indication to switch the UE (102) from a source cell (204a) to a candidate cell (204b) ; and

performing (320) , with the UE (102) , a lower-layer triggered mobility (LTM) procedure to switch the UE (102) from the source cell (204a) to the candidate cell (204b) according to the indication included in the CSC for the UE group.
The method of claim 12, wherein the CSC includes common information for the UE group for switching all UEs of the UE group to the candidate cell (204a) based on the common information.
The method of claim 12, wherein the indication includes a first portion dedicated to the UE (102) and a second portion dedicated to a different UE of the UE group, the switching of the UE (102) from the source cell (204a) to the candidate cell (204b) being based on the first portion.
An apparatus for wireless communication comprising a memory, a transceiver, and a processor coupled to the memory and the transceiver, the apparatus being configured to implement a method as in any of claims 1-14.