Managing timing alignment with multiple receivers in wireless communication system

Abstract

To manage synchronization, a user equipment: receives a configuration comprising a first timing advance (TA) value and a second TA value from a radio access network (RAN) (606); operating a first TA timer (TAT) corresponding to the first TA value to manage synchronization of a first uplink (UL) transmission with a first receiver in the RAN (608); operating a second TAT corresponding to the second TA value to manage synchronization of a second UL transmission with a second receiver in the RAN (610); stopping the first UL transmission in response to expiration of the first TAT (612); and stopping the second UL transmission in response to expiration of the second TAT (614).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of the filing dates of U.S. Provisional Patent Application No. 63 / 393,818, filed on July 29, 2022, entitled “MAINTAINING ATA VALUE IN A MULTIPLE-TRP SCENARIO IN A WIRELESS COMMUNICATION SYSTEM,” and U.S. Provisional Patent Application No. 63 / 393,591, filed on July 29, 2022, entitled “MANAGING MULTIPLE TIMING ADVANCE VALUES FOR MULTIPLE TRANSMIT AND / OR RECEIVE POINTS,” which are hereby expressly incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates generally to wireless communications, and more particularly to maintaining a TA value in a serving cell at a UE side or a NW / base station (BS) side, and / or supporting the updating and expiration of a time alignment timer (TAT). The technology can be applied to a multiple transmission and / or reception point (M-TRP) scenario. Background Art

[0004] This background description is provided for the purpose of generally presenting the context of the present disclosure. The work of the presently named inventors, to the extent that it is described in this background section, and aspects of the specification that might not have been considered prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art to the present disclosure.

[0005] Generally speaking, a base station operating a cellular radio access network (RAN) uses a certain radio access technology (RAT) and multiple layers of a protocol stack to communicate with a user equipment (UE). For example, the physical layer (PHY) of the RAT provides a transport channel to the medium access control (MAC) sublayer, which in turn provides a logical channel to the radio link control (RLC) sublayer, and the RLC sublayer in turn provides data transfer services to the packet data convergence protocol (PDCP) sublayer. The radio resource control (RRC) sublayer is arranged above the PDCP sublayer.

[0006] The RRC sublayer specifies: an RRC_IDLE state, in which the UE does not have an active radio connection with a base station; an RRC_CONNECTED state, in which the UE has an active radio connection with a base station; and an RRC_INACTIVE state, which is used to allow the UE to transition back to the RRC_CONNECTED state more quickly due to radio access network (RAN) level base station coordination and RAN paging procedures. In some cases, a UE in the RRC_IDLE or RRC_INACTIVE state has only a relatively small packet to send. In some such cases, a UE in the RRC_IDLE or RRC_INACTIVE state performs early data transmission without transitioning to the RRC_CONNECTED state.

[0007] Regarding the PHY layer, in some cases, different channel or reference signal (RS) configurations correspond to different beam indication techniques. For most DL transmissions (e.g., physical downlink shared channel (PDSCH), physical downlink control channel (PDCCH), or channel state information (CSI) resource signal (CSI-RS)), the transmission configuration indication (TCI) framework and TCI state are applicable and configured for such transmissions. However, in some cases, PDCCH transmission requires MAC-CE to further indicate the TCI state within the configured TCI state, and PDSCH transmission therefore similarly requires MAC-CE and downlink control information (DCI). For the physical uplink shared channel (PUSCH), the UL beam indication relies on the index of the sounding reference signal (SRS) resource on which the UE has sent at least once. In some implementations, for the physical uplink control channel (PUCCH), the MAC-CE indicates the spatial relationship for the UE to derive the UL beam. In another implementation, the spatial relationship is also configured in the SRS resource set, which indicates that the same UL beam applies to all SRS resources in the SRS resource set. However, these messages may also require large signaling overhead when many channels or RSs share the same beam. Summary of the invention

[0008] An example embodiment of the technology of the present disclosure is a method for managing synchronization, which is implemented in a user equipment (UE) and includes: receiving a configuration including a first timing advance (TA) value and a second TA value from a radio access network (RAN); operating a first TA timer (TAT) corresponding to the first TA value to manage synchronization of a first uplink (UL) transmission with a first receiver in the RAN; operating a second TAT corresponding to the second TA value to manage synchronization of a second UL transmission with a second receiver in the RAN; stopping the first UL transmission in response to expiration of the first TAT; and stopping the second UL transmission in response to expiration of the second TAT.

[0009] Another example embodiment of the techniques is a user equipment (UE) comprising: a transceiver; and processing hardware configured to implement the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A is a block diagram of an example system in which distributed base stations and / or user equipment (UE) may implement the techniques of the present disclosure;

[0011] Figure 1B is a block diagram of an example base station including a central unit (CU) and a distributed unit (DU) of a distributed base station, wherein the central unit and the distributed unit may be Figure 1A Operate in a system

[0012] Figure 2A is a block diagram of an example protocol stack, Figure 1A to Figure 1B The UE can communicate with the base station according to the protocol stack;

[0013] Figure 2B is a block diagram of an example protocol stack, Figure 1A to Figure 1B The UE can communicate with the DU and CU of the base station according to the protocol stack;

[0014] Figure 3A Yes Figure 2A and / or Figure 2B A block diagram of the detailed structure of each sub-layer of the depicted protocol stack, including scheduling and / or priority handling functions;

[0015] Figure 3B is with Figure 3A A block diagram of the detailed structure of the various sub-layers of a similar protocol stack, but wherein the structure includes a logical channel prioritization function;

[0016] Figure 4A is a block diagram of a HARQ entity including a plurality of HARQ processes and communicating using a transport channel of a plurality of TRPs;

[0017] Figure 4B is with Figure 4A A block diagram of a HARQ entity similar to that of FIG. 1 , but wherein the HARQ entity includes multiple HARQ process groups associated with multiple transport channels to multiple TRPs;

[0018] Figure 4C is with Figure 4A A block diagram of a HARQ entity similar to that of FIG. 1 , but wherein the HARQ entity communicates with a single TRP;

[0019] Figure 5A is a message passing diagram for an example scenario in which a UE synchronizes with a first TRP and / or a second TRP to perform communications with a base station;

[0020] Figure 5B is with Figure 5A Messaging diagram for a similar example scenario, but where the UE receives UL and DL configuration parameters in separate radio resource configuration messages;

[0021] Figure 5C is with Figure 5A A message passing diagram for a similar example scenario, but where the base station sends the UL configuration parameters to the UE via the second TRP instead of the first TRP;

[0022] Figure 5D is with Figure 5A a message passing diagram for a similar example scenario, but where the UE receives a response from the base station via the first TRP instead of via the second TRP when performing a random access procedure;

[0023] Figure 5E is with Figure 5A Message passing diagram for a similar example scenario, but where the UE receives the PDCCH order via the first TRP instead of the second TRP;

[0024] Figure 6 Among them Figure 1A and / or Figure 1B Flowchart of an example method for a UE to determine whether to stop sending UL transmissions associated with a first TA value or a second TA value based on the UE detecting expiration of a first TAT or a second TAT;

[0025] Fig. 7A is with Figure 6 A flow chart of a similar example method, but wherein the UE determines whether to flush the HARQ buffer of the first HARQ process set or the second HARQ process set based on the detection;

[0026] Figure 7B is with Fig. 7AA flow chart of a similar example method, but wherein the UE determines, based on the detection, whether to flush a HARQ buffer associated with a first TA value and a second TA value or to avoid flushing the HARQ buffer;

[0027] Fig. 8A is with Figure 6 A flow chart of a similar example method, but wherein the UE determines based on the detection to clear a configured UL grant associated with a first TA value or a second TA value;

[0028] Figure 8B is with Fig. 8A A flow chart of a similar example method, but wherein the UE determines whether to clear a configured UL grant associated with a first TA value and / or a second TA value or to refrain from clearing the configured UL grant based on the detection;

[0029] Fig.9A is with Figure 6 A flow chart of a similar example method, but wherein the UE determines based on the detection whether to release PUCCH resources associated with the first TA value or the second TA value;

[0030] Fig. 9B is with Fig.9A A flow chart of a similar example method, but wherein the UE determines based on the detection whether to release PUCCH resources associated with the first TA value and / or the second TA value or to avoid releasing the PUCCH resources;

[0031] Fig. 10A is with Figure 6 A flow chart of a similar example method, but wherein the UE determines based on the detection whether to release SRS resources associated with the first TA value or the second TA value;

[0032] Fig. 10B is with Fig. 10A A flow chart of a similar example method, but wherein the UE determines, based on the detection, whether to release SRS resources associated with the first TA value and / or the second TA value or to avoid releasing the SRS resources;

[0033] Fig.11A is with Figure 6 A flow chart of a similar example method, but wherein the UE determines based on the detection to clear PUSCH resources associated with the first TA value or the second TA value for CSI reporting;

[0034] Fig. 11B is with Fig.11A A flow chart of a similar example method, but wherein the UE determines based on the detection whether to clear PUSCH resources associated with the first TA value and / or the second TA value for CSI reporting or to avoid clearing the PUSCH resources;

[0035] Fig. 12A is with Figure 6 A flow chart of a similar example method, but wherein the UE determines based on the detection whether to trigger a CBRA procedure associated with the first TA value or the second TA value;

[0036] Fig. 12B is with Fig. 12A A flow chart of a similar example method, but wherein the UE determines based on the detection whether to send a MAC CE indicating expiration of a first TA value or a second TA value;

[0037] Fig. 12C is with Fig. 12A A flow chart of a similar example method, but wherein the UE determines based on the detection whether to send an RRC message indicating expiration of a first TA value or a second TA value;

[0038] Fig.12D is with Fig. 12A A flow chart of a similar example method, but wherein the UE determines based on the detection whether to send a PUCCH transmission indicating expiration of a first TA value or a second TA value;

[0039] Fig.12E Among them Figure 1A and / or Figure 1B The UE determines whether to send a signal based on whether the UE detects that the first TAT and / or the second TAT expires. FIG. 12B to FIG. 12D A flowchart of an example method in which one of the transmissions indicating expiration of a first TA value or a second TA value also triggers a CBRA process;

[0040] Fig.13 Among them Figure 1A and / or Figure 1B A flowchart of an example method of a UE receiving a first TA value and a second TA value and starting or restarting a single TAT to maintain a first UL synchronization and a second UL synchronization with a base station; and

[0041] Fig.14 Among them Figure 1A and / or Figure 1B Flowchart of an example method in which a UE receives a first TA value and an increment value from a base station and then determines a second TA value based on the first TA value and the increment value. DETAILED DESCRIPTION

[0042] The techniques discussed below may be applicable to M-TRP scenarios involving multiple timing advance (TA) values, where the UE maintains multiple TA values ​​in at least one serving cell. The methods discussed below allow the UE and / or base station to maintain TA alignment in M-TRP scenarios. These techniques also allow the UE to indicate / update TA values ​​for various TAT ​​operation frameworks. These techniques may be applicable to LTE, NR, or any other suitable RAT.

[0043] First reference Figure 1A , the example wireless communication system 100 includes a UE 102, a base station (BS) 104, a base station 106, and a core network (CN) 110. The base stations 104 and 106 may operate in a RAN 105 connected to the core network (CN) 110. For example, the CN 110 may be implemented as an evolved packet core (EPC) 111 or a fifth generation (5G) core (5GC) 160. In another example, the CN 110 may also be implemented as a sixth generation (6G) core.

[0044] Base station 104 may cover one or more cells (e.g., cells 124 and 125) having one or more transmission and / or reception points (TRPs), and base station 106 may similarly cover one or more cells (e.g., cell 126) having one or more TRPs. For example, base station 104 operates cell 124 having TRPs 107-1 and 107-2 and operates cell 125 having TRP 107-3, and base station 106 operates cell 126 having TRPs 108-1 and 108-2. Cells 124 and 125 operate on one or more of the same carrier frequencies. Cell 126 may operate on the same one or more carrier frequencies as cells 124 and 125. Alternatively, cell 126 may operate on one or more carrier frequencies different from cells 124 and 125. In some implementations, base station 104 connects each of TRPs 107-1, 107-2, and 107-3 via a fiber optic connection or an Ethernet connection. If base station 104 is a gNB, cells 124 and 125 are NR cells. If base station 104 is a (ng-)eNB, cells 124 and 125 are Evolved Universal Terrestrial Radio Access (EUTRA) cells. Similarly, if base station 106 is a gNB, cell 126 is an NR cell, and if base station 106 is a (ng-)eNB, cell 126 is an EUTRA cell. Cells 124, 125, and 126 may be located in the same radio access network notification area (RNA) or in different RNAs. In general, RAN 105 may include any number of base stations, and each of the base stations may cover one, two, three, or any other suitable number of cells. UE 102 may support at least 5G NR (or simply "NR") or E-UTRA air interface to communicate with base station 104 via TRP 107-1, TRP107-2, and / or TRP-3. Similarly, UE 102 may support at least 5G NR (or simply "NR") or E-UTRA air interface to communicate with base station 106 via TRP 108-1 and / or TRP 108-2. Each of base stations 104, 106 may be connected to CN 110 via an interface (e.g., S1 or NG interface). Base stations 104 and 106 may also be interconnected via an interface (e.g., X2 or Xn interface) for interconnecting NG RAN nodes.

[0045] When a base station (e.g., base station 104 or 106) sends DL data via a TRP (e.g., TRP 107-1, TRP 107-2, TRP 107-3, TRP 108-1, or TRP 108-2), the base station 104 may generate a packet including the data and send the packet to the TRP 107-1. For example, the packet may be a fronthaul transport protocol data unit. The TRP extracts the data from the packet and sends the data. In some implementations, the base station 104 may include control information of time-critical control and management information directly related to the data in the packet, and the TRP may send the data based on the control information. In some implementations, the data includes in-phase and quadrature (IQ) data, a physical layer bit sequence, or a MAC PDU. When the TRP receives data from a UE (e.g., UE 102), the TRP generates a packet including the data and sends the packet to the base station 104. In some implementations, the data includes IQ data, a physical layer bit sequence, or a MAC PDU.

[0046] Among other components, the EPC 111 may include a serving gateway (SGW) 112, a mobility management entity (MME) 114, and a packet data network gateway (PGW) 116. In general, the SGW 112 is configured to deliver user plane packets associated with audio calls, video calls, Internet services, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The PGW 116 provides connectivity from the UE 102 to one or more external packet data networks (e.g., an Internet network and / or an Internet Protocol (IP) Multimedia Subsystem (IMS) network). The 5GC 160 includes a user plane function (UPF) 162 and an access and mobility management function (AMF) 164 and / or a session management function (SMF) 166. Generally, UPF 162 is configured to deliver user plane packets associated with audio calls, video calls, Internet services, etc., AMF 164 is configured to manage authentication, registration, paging and other related functions, and SMF 166 is configured to manage PDU sessions.

[0047] like Figure 1A As shown, base station 104 supports cells 124 and 125, and base station 106 supports cell 126. Cells 124, 125, and 126 may partially overlap, so that UE 102 may select a cell, reselect a cell, or switch from one of cells 124, 125, and 126 to another. In order to exchange messages or information directly, base station 104 and base station 106 may support an X2 or Xn interface. In general, CN 110 may be connected to any suitable number of base stations supporting NR cells and / or EUTRA cells.

[0048] The base station 104 is equipped with processing hardware 130, which may include one or more general-purpose processors (e.g., CPUs) and non-transitory computer-readable memory storing instructions, and the one or more general-purpose processors execute the instructions. Additionally or alternatively, the processing hardware 130 may include a dedicated processing unit. The processing hardware 130 may include a PHY controller 132, which is configured to send data and control signals on physical DL channels and DL reference signals with one or more user devices (e.g., UE 102) via one or more TRPs (e.g., TRP 107-1, TRP 107-2, and / or TRP 107-3). The PHY controller 132 is also configured to receive data and control signals on physical UL channels and / or UL reference signals with one or more user devices via one or more TRPs (e.g., TRP 107-1, TRP 107-2, and / or TRP 107-3). In an example implementation, the processing hardware 130 includes a MAC controller 134 configured to perform a random access (RA) procedure with one or more user devices, manage UL timing advance for one or more user devices, receive UL MAC PDUs from one or more user devices, and send DL MAC PDUs to one or more user devices. The processing hardware 130 may also include an RRC controller 136 to implement procedures and message delivery at the RRC sublayer of the protocol communication stack. The base station 106 may include processing hardware 140 similar to the processing hardware 130. In particular, components 142, 144, and 146 may be similar to components 132, 134, and 136, respectively.

[0049] UE 102 is equipped with processing hardware 150, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors, and / or dedicated processing units. PHY controller 152 is also configured to receive data and control signals on physical DL channels and / or DL ​​reference signals with base station 104 or 106 via one or more TRPs (e.g., TRP107-1, TRP 107-2, TRP 107-3, TRP 108-1, and / or TRP 108-2). PHY controller 152 is also configured to send data and control signals on physical UL channels and / or UL reference signals with base station 104 or 106 via one or more TRPs (e.g., TRP 107-1, TRP 107-2, TRP 107-3, TRP 108-1, and / or TRP 108-2). In an example implementation, the processing hardware 150 includes a MAC controller 154 configured to perform random access procedures with the base station 104 or 106, manage UL timing advance for one or more user devices, send UL MAC PDUs to the base station 104 or 106, and receive DL MAC PDUs from the base station 104 or 106. The processing hardware 150 may also include an RRC controller 156 to implement procedures and messaging at the RRC sublayer of the protocol communication stack.

[0050] Figure 1B An example distributed or decomposed implementation of one or both of the base stations 104, 106 is depicted. In this implementation, each of the base stations 104 and / or 106 includes a central unit (CU) 172 and one or more distributed units (DUs) 174. The CU 172 includes processing hardware, such as one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the general-purpose processors, and / or dedicated processing units. For example, the CU 172 may include a PDCP controller (e.g., PDCP controllers 134, 144), an RRC controller (e.g., RRC controllers 136, 146), and / or an RRC inactive controller (e.g., RRC inactive controllers 138, 148). In some implementations, the CU 172 may include an RLC controller configured to manage or control one or more RLC operations or processes. In other implementations, the CU 172 does not include an RLC controller.

[0051] Each of the DUs 174 also includes processing hardware, which may include one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or a dedicated processing unit. For example, the processing hardware may include: a MAC controller (e.g., MAC controllers 132, 142), which is configured to manage or control one or more MAC operations or processes (e.g., random access processes), and / or an RLC controller, which is configured to manage or control one or more RLC operations or processes. The processing hardware may also include a physical layer controller, which is configured to manage or control one or more physical layer operations or processes.

[0052] In some implementations, the RAN 105 supports integrated access and backhaul (IAB) functionality. In some implementations, the DU 174 operates as an (IAB) node and the CU 172 operates as an IAB donor.

[0053] In some implementations, the CU 172 may include a logical node CU-CP 172A that hosts a control plane portion of a PDCP protocol of the CU 172. The CU 172 may also include a logical node CU-UP 172B that hosts a user plane portion of a PDCP protocol and / or SDAP protocol of the CU 172. The CU-CP 172A may send control information (e.g., RRC messages, F1 application protocol messages), and the CU-UP 172B may send data packets (e.g., SDAP PDUs or IP packets).

[0054] The CU-CP 172A may be connected to multiple CU-UPs 172B via an E1 interface. The CU-CP 172A selects an appropriate CU-UP 172B for the service requested by the UE 102. In some implementations, a single CU-UP 172B may be connected to multiple CU-CPs 172A via an E1 interface. If the CU-CP 172A and the DU 174 belong to a gNB, the CU-CP 172A may be connected to one or more DUs 174s via an F1-C interface and / or an F1-U interface. If the CU-CP 172A and the DU 174 belong to an ng-eNB, the CU-CP 172A may be connected to the DU 174 via a W1-C interface and / or a W1-U interface. In some implementations, one DU 174 may be connected to multiple CU-UPs 172B under the control of the same CU-CP 172A. In such implementations, the connection between the CU-UP 172B and the DU 174 is established by the CU-CP 172A using a bearer context management function.

[0055] Figure 2A An example protocol stack 200 is shown in a simplified manner, according to which the UE 102 can communicate with an eNB / ng-eNB or gNB (e.g., one or both of the base stations 104, 106).

[0056] In the example stack 200, the physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA MAC sublayer 204A, which in turn provides logical channels to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A in turn provides RLC channels to the EUTRA PDCP sublayer 208 and, in some cases, to the NR PDCP sublayer 210. Similarly, the NRRPHY 202B provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B. The NR RLC sublayer 206B in turn provides data transfer services to the NR PDCP sublayer 210. The NR PDCP sublayer 210 may in turn provide data to the SDAP sublayer 212 or the RRC sublayer ( Figure 2A In some implementations, UE 102 supports both EUTRA and NR stacks, such as Figure 2A As shown, to support switching between EUTRA and NR base stations and / or to support dual connectivity (DC) implemented via EUTRA and NR interfaces. Figure 2A As shown, the UE 102 can support NR PDCP 210 layered on EUTRA RLC 206A, and the SDAP sublayer 212 layered on the NR PDCP sublayer 210.

[0057] The EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 receive packets, which may be referred to as SDUs (e.g., from an IP layer layered directly or indirectly on the PDCP layer 208 or 210), and output packets, which may be referred to as PDUs (e.g., to the RLC layer 206A or 206B). Except for cases where the difference between SDUs and PDUs is relevant, for simplicity, this disclosure refers to both SDUs and PDUs as "packets".

[0058] On the control plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide the RRC sublayer with Figure 2AThe NR PDCP sublayer 210 may provide a signaling radio bearer (SRB) to exchange, for example, RRC messages or NAS messages. On the user plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide a data radio bearer (DRB) to support data exchange. The data exchanged on the NR PDCP sublayer 210 may be a SDAP PDU, an IP packet, or an Ethernet packet.

[0059] Therefore, the radio protocol stack can be functionally split, such as Figure 2B 206B, NR MAC 204B, and NR PHY 202B) are delegated to the DU. To support the connection to the 5GC, the NR PDCP 210 provides SRBs to the RRC 214, and the NR PDCP 210 provides DRBs to the SDAP 212 and SRBs to the RRC 214.

[0060] Figure 3A Detailed structure 300A of the NR layer 2 protocol stack 200 or 250 for the base station 104 or 106 is shown. PHY 202 ( Figure 3A The MAC sublayer 204 includes a scheduling and / or priority handling function for scheduling and / or prioritizing DL and UL transmissions with one or more user devices. The MAC sublayer 204 also includes a multiplexing function for DL ​​transmissions with a specific user device and / or a demultiplexing function for UL transmissions with the specific user device. The MAC sublayer 204 also includes a hybrid automatic repeat request (HARQ) entity for DL ​​transmission and / or UL transmission with a specific user device on a specific DL component carrier (CC) and / or a specific UL CC. The RLC sublayer 206 includes a segmentation and automatic repeat request (ARQ) function for DL ​​data and UL data for communication with one or more UEs. The PDCP sublayer 210 provides a radio bearer to the SDAP sublayer 212, and includes (i) security and (ii) robust header compression (ROHC) functions for (i) integrity protection and / or encryption / description and (ii) header compression / decompression, respectively. The SDAP sublayer 212 provides 5GC QoS flows to the upper layer.

[0061] Figure 3B Detailed structure 300B of the NR layer 2 protocol stack 200 or 250 for UE 102 is shown, similar to structure 300A. PHY 202 ( Figure 3BThe MAC sublayer 204 includes one or more HARQ entities, each for DL ​​transmission and / or UL transmission with the base station 104 or 106 on a specific DL CC and / or a specific UL CC. The MAC sublayer 204 also includes logical channel prioritization and multiplexing functions for UL transmission to the base station 104 or 106, and includes a demultiplexing function for DL ​​transmission from the base station 104 or 106. The RLC sublayer 206 includes segmentation and automatic repeat request (ARQ) functions for DL ​​data and UL data communicated with the base station 104 and / or 106. The PDCP sublayer 210 provides radio bearers to the SDAP sublayer 212, and includes (i) security and (ii) robust header compression (ROHC) functions for (i) integrity protection and / or encryption / description and (ii) header compression / decompression, respectively. The SDAP sublayer 212 provides 5GC QoS flow to the upper layer.

[0062] FIG. 4A to FIG. 4C shows the HARQ entity for a specific CC y Different implementations of multi-TRP (mTRP) operation on (e.g., UL CC or DL ​​CC), which can be implemented in UE 102, base station 104 or 106, or DU 174 of base station 104 or 106.

[0063] First reference Figure 4A , which depicts a HARQ entity 400A. In some implementations, the HARQ entity 400A includes HARQ processes 1, ..., N for communicating with TPRs 1, ..., m. N is an integer and greater than zero, and m is an integer and greater than zero. For example, N is 8, 16, 32, etc., and m is 2, 3, 4, etc.

[0064] Next, Figure 4B A further implementation of a HARQ entity 400B is depicted, similar to the HARQ entity 400A. The difference between the implementations of the HARQ entity 400B and 400A is that the HARQ entity 400B divides the HARQ processes 1, ..., N into m groups, where each group is used for communication with a specific TRP.

[0065] Next, Figure 4C The implementation of a HARQ entity 400C (eg, HARQ entity k) is depicted, which is similar to the HARQ entity 400A. The difference between the implementations of the HARQ entity 400C and 400A is that the HARQ entity 400C is used to perform a specific CC (eg, CC k ) with a specific TRP (e.g., TRP k), where 1≤k≤m. In other words, UE 102 uses HARQ entities 1, ..., m to communicate with a RAN node (e.g., base station 104 or 106, or DU 174) via TRP 1, ..., m on each UL CC, respectively. Similarly, the RAN node uses HARQ entities 1, ..., m to communicate with UE 102 via TRP 1, ..., m of the RAN node (e.g., base station 104 or 106, or DU 174) on each DL CC, respectively.

[0066] Next, refer to FIG. 5A to FIG. 5E To discuss the Figure 1A The various components of mTRP and several example scenarios related to mTRP operation. FIG. 5A to FIG. 5E Identical events are marked with the same reference numerals.

[0067] First reference Figure 5A , in scenario 500A, base station 104 operates cell 124, TRP 107-1, and TRP 107-2. In scenario 500A, base station 104 broadcasts 504, 506 one or more synchronization signal blocks (SSBs) and 508, 510 system information via TRP 107-1 (e.g., periodically). In some implementations, the system information includes a master information block (MIB) and / or a system information block (SIB). In some examples, the SIB includes SIB1, and also includes SIB2, SIB3, SIB4, and / or SIB5. UE 102 initially operates 502 in an idle state (e.g., RRC_IDLE state). UE 102 in the idle state receives 504, 506 SSBs and 508, 510 system information from base station 104 via TRP 107-1. In some implementations, the UE 102 detects that the base station 104 transmits the SSB via the TRP 107-1. In some implementations, the UE 102 then performs downlink synchronization with the base station 104 on the cell 124 via the TRP 107-1 using one of the SSBs, and receives 508, 510 system information via the TRP 107-1 based on the SSBs.

[0068] At a later time, the UE 102 determines to perform 590 a random access procedure to perform 592 an RRC connection establishment procedure. In response to the determination, the UE 102 sends 512 a first random access preamble to the TRP 107-1 on a time / frequency resource and / or a random access channel (RACH) opportunity. The TRP 107-1 then forwards 514 the first random access preamble to the base station 104. In some implementations, the UE 102 selects an SSB from the SSBs for which the RSRP obtained by the UE 102 is higher than a first threshold (e.g., rsrp-ThresholdSSB) for the random access procedure. In other implementations, in the case where the RSRP of any SSB in the SSBs is not higher than the first threshold, the UE 102 selects an SSB from the SSBs and uses the SSB to determine the first random access preamble. In some such cases, the UE 102 randomly selects the SSB from the SSBs, or selects based on the UE implementation. The UE 102 then determines a first random access preamble, a time / frequency resource, and / or a RACH opportunity based on the selected SSB and the random access configuration parameters included in the system information (e.g., SIB1). In some implementations, the random access configuration parameters indicate one or more associations between (i) the SSB and (ii) the random access preamble, the RACH opportunity, and / or the time / frequency resource. Based on the selected SSB and the association, the UE 102 determines the first random access preamble, the RACH opportunity, and / or the time / frequency resource to send the first random access preamble.

[0069] In response to the first random access preamble, the base station 104 sends 516 a first random access response to the TRP 107-1. The TRP 107-1 then forwards 518 the first random access response to the UE 102. In some implementations, the base station 104 or the TRP 107-1 identifies an SSB associated with the first random access preamble, RACH opportunity, and / or time / frequency resource. In some cases where a single SSB is associated with the first random access preamble, RACH opportunity, and / or time / frequency resource, the identified SSB is the SSB selected by the UE 102. In some cases where multiple SSBs are associated with the first random access preamble, RACH opportunity, and / or time / frequency resource, the identified SSB is the same as or different from the SSB selected by the UE 102. In such implementations, the base station 104 sends a first random access response to the UE 102 via the TRP 107-1 based on the identified SSB. The base station 104 includes the first preamble ID and the first TA command in the first random access response. The first preamble ID identifies the first random access preamble, and the first TA command includes a first TA value. The UE applies the first TA value and determines or maintains 520 an uplink synchronized (e.g., time aligned) with the TRP 107-1 after applying the first TA value (e.g., in response to applying the first TA value). The UE 102 applies the first TA value to send UL transmissions (e.g., PUCCH transmissions, PUSCH transmissions, and / or sounding reference signal transmissions) until a new or different TA value that updates the first TA value is received from the base station 104. In some implementations, the UE 102 starts a first time alignment timer (TAT) after or upon receiving the first TA command to maintain a UL synchronization state with the TRP 107-1 or the base station 104. In some implementations, the base station 104 includes a UL grant (i.e., a RAR grant) in the random access response.

[0070] In some implementations, the base station 104 starts a first TAT to maintain first UL synchronization of UL and / or DL ​​communications with the UE 102 via the TRP 107-1 after sending a random access response or a first TA command to the UE 102. In some implementations, the TRP 107-1 generates timing information for or based on a first random access preamble received from the UE 102 and sends the timing information to the base station 104. In some examples, the timing information indicates a propagation delay or a propagation delay shift. Based on the timing information received from the TRP 107-1, the base station 104 determines a first TA value.

[0071] Blocks 512, 514, 516, 518, and 520 are Figure 5A are collectively referred to as random access process 590.

[0072] During or after the random access procedure 590, the UE 102 sends 522, 524 an RRC setup request message (e.g., an RRCSetupRequest message) to the base station via TRP 107-1. In some implementations, the UE 102 sends the RRC setup request message using the UL grant received in the random access response. In response to the RRC setup request message, the base station 104 sends 526, 528 an RRC setup message (e.g., an RRCSetup message) to the UE 102 via TRP 107-1. In some implementations, the base station 104 sends a MAC PDU including contention resolution (e.g., a MAC control element (CE)) to the UE 102 to resolve contention for the random access procedure. In some implementations, the base station 104 includes the RRC setup message in the MAC PDU. In another implementation, after sending the MAC PDU, the base station 104 sends another MAC PDU including the RRC setup message to the UE 102. In response to the RRC setup message, the UE 102 transitions 530 to a connected state (e.g., RRC_CONNECTED) and sends 532, 534 an RRC setup complete message (e.g., RRCSetupComplete message) to the base station 104 via the TRP 107-1. In some implementations, after performing an RRC connection establishment procedure with the UE 102, the base station 104 performs a security activation procedure with the UE 102 to activate security protection (e.g., integrity protection / integrity check and encryption / decryption) for UL data and DL data communicated between the UE 102 and the base station 104. In another implementation, after performing an RRC connection establishment procedure or a security activation procedure, the base station 104 performs a radio bearer configuration procedure with the UE 102 to configure SRB2 and / or DRB for the UE 102.

[0073] After performing an RRC connection establishment procedure, a security activation procedure, or a radio bearer configuration procedure, the base station 104 sends 536, 538 an RRC reconfiguration message (e.g., an RRCReconfiguration message) including a channel state information (CSI) resource configuration and a CSI report configuration to the UE 102 via TRP 107-1. In response, the UE 102 sends 540, 542 an RRC reconfiguration completion message (e.g., an RRCReconfiguration Complete message) to the base station 104 via TRP 107-1. In some implementations, the CSI resource configuration includes configuration parameters for configuring a channel state information reference signal (CSI-RS) for measurement by the UE 102. The base station 104 sends the CSI-RS via TRP 107-2 according to the CSI resource configuration. The UE 102 performs measurements on the CSI-RS according to the CSI resource configuration. In some implementations, the CSI resource configuration includes configuration parameters for configuring an SSB for measurement by the UE 102. The base station 104 sends the SSB via TRP 107-2. The UE 102 performs measurements on the SSB according to the CSI resource configuration. In other implementations, the RRC reconfiguration message or the CSI resource configuration does not include configuration parameters for configuring the SSB. In some such cases, the base station 104 still sends the SSB via TRP 107-2, and the UE 102 performs measurements on the SSB. Based on the CSI report configuration, the UE 102 generates a CSI report from the measurement of the CSI-RS or SSB, and sends 544, 546 the CSI report to the base station 104 via TRP 107-1. In some implementations, the UE 102 sends the CSI report to the base station 104 on the PUCCH via TRP 107-1. In some implementations, the CSI report configuration configures periodic or semi-persistent reporting, or the CSI report configuration configures semi-persistent or aperiodic reporting triggered by DCI. The CSI report includes a periodic CSI report, a semi-persistent CSI report and / or an aperiodic CSI report.

[0074] In some implementations, the base station 104 includes the CSI resource configuration and / or the CSI report configuration in a CSI measurement configuration (e.g., CSI-MeasConfig IE). The base station 104 then includes the CSI measurement configuration in the RRC reconfiguration message of events 536, 538. In other implementations, the CSI resource configuration includes NZP-CSI-RS-Resource IE, NZP-CSI-RS-ResourceSet IE, CSI-SSB-ResourceSet IE, CSI-Resource Config IE, and / or CSI-ReportConfig IE.

[0075] Boxes 536, 538, 540, 542, 544, and 546 are Figure 5A The CSI resource configuration and CSI reporting process 594 are collectively referred to as CSI resource configuration and CSI reporting process 594.

[0076] After receiving the CSI report at event 546, the base station 104 determines, based on the CSI report, to communicate with the UE 102 via TRP 107-2 while maintaining a link with the UE 102 via TRP 107-1. In some implementations, the base station 104 makes the determination based on one or more capabilities of the UE 102. In response to the determination, the base station 104 sends 548, 550 an RRC reconfiguration message to the UE 102 via TRP 107-1, the RRC reconfiguration message including DL and UL configuration parameters for DL ​​and UL communications, respectively, with the base station 104 via TRP 107-2. In some implementations, the base station 104 includes the DL and UL configuration parameters in a CellGroupConfig IE and includes the CellGroupConfig IE in the RRC reconfiguration message. In some implementations, the base station 104 includes the DL configuration parameters in a bandwidth part (BW) IE (such as a BWP-DownlinkDedicated IE) and includes the BWP-DownlinkDedicated IE in the RRC reconfiguration message. In some implementations, the base station 104 includes the UL configuration parameters in a BWP-UplinkDedicated IE and includes the BWP-UplinkDedicated IE in the RRC reconfiguration message.

[0077] In response to the RRC reconfiguration complete message, UE 102 sends 552, 554 an RRC reconfiguration complete message to base station 104 via TRP 107-1. In some implementations, UE 102 applies the DL configuration parameters upon receiving the RRC reconfiguration message at event 554. In such implementations, UE 102 performs 556 DL communications with base station 104 via TRP 107-2 in accordance with the DL configuration parameters while performing DL and UL communications with base station 104 via TRP 107-1. In some implementations, UE 102 refrains from performing UL communications in accordance with the UL configuration parameters until after performing a random access procedure with base station 104 via TRP 107-2 at event 598. In other implementations, UE 102 refrains from performing DL communications with base station 104 via TRP 107-2 until after performing a random access procedure with base station 104 via TRP 107-2 at event 598. In some implementations, base station 104 avoids performing UL communications and / or configuring UL configuration parameters until after a random access procedure with base station 104 via TRP 107-2 is completed at event 598. In some implementations, base station 104 avoids performing DL communications and / or configuring DL configuration parameters until after a random access procedure with base station 104 via TRP 107-2 is completed at event 598.

[0078] In some implementations, at event 556, base station 104 and UE 102 use Figure 4A , Figure 4B or Figure 4C 107-2 to perform DL communication with base station 104 via TRP 107-1 and TRP 107-2. In some cases, such as for Figure 4B For the HARQ entity 400B, the DL configuration parameters of events 548 and 550 include HARQ configuration parameters. The HARQ configuration parameters configure the first HARQ process ID set and the second HARQ process ID set. In some cases, the first HARQ process ID set and the second HARQ process ID set are for TRP 107-1 and TRP 107-2, respectively. The first HARQ process ID set and the second HARQ process ID set identify the first HARQ process set of the HARQ entity and the second HARQ process set of the HARQ entity, respectively. In some implementations, the first HARQ process ID set and the second HARQ process ID set are not the same. In other implementations, some HARQ process IDs of the first HARQ process ID set and the second HARQ process ID set are the same, while other HARQ process IDs are different.

[0079] In some implementations, the base station 104 sends one or more MAC control elements (CE) or DCI to the UE 102 to change or update one or more HARQ process IDs in the first HARQ process ID set. In some implementations, the base station 104 sends one or more MAC CEs or DCIs to the UE 102 to change or update one or more HARQ process IDs in the second HARQ process ID set. In some alternative implementations, the base station 104 does not configure the first HARQ process ID set and the second HARQ process ID set in the DL configuration parameters. In some implementations, the base station 104 determines the first HARQ process ID set and the second HARQ process ID set for mTRP operation based on pre-configuration. In another implementation, the first HARQ process ID set and the second HARQ process ID set are specific predetermined IDs (e.g., as specified in the 3GPP specification). In yet another implementation, the base station 104 determines the first HARQ process ID set and the second HARQ process ID set based on a rule.

[0080] In some implementations, when the base station 104 determines to schedule the UE 102 to receive a DL transmission to the TRP 107-1, the base station 104 selects a HARQ process ID from the first set of HARQ process IDs, and sends a DCI including a DL assignment and the selected HARQ process ID to the UE 102. The UE 102 uses the HARQ process identified by the selected HARQ process ID, and uses the HARQ process and a UL grant to receive the DL transmission from the base station 104. Similarly, when the base station 104 determines to schedule the UE 102 to send a UL transmission to the TRP 107-2, the base station 104 selects a HARQ process ID from the second set of HARQ process IDs, and sends a DCI including a UL grant and the selected HARQ process ID to the UE 102. The UE 102 uses the HARQ process identified by the selected HARQ process ID, and uses the HARQ process and the DL assignment to receive the DL transmission from the base station 104.

[0081] In some implementations, the one or more capabilities include at least one first capability indicating that the UE 102 supports mTRP operation (e.g., a Release 16 capability field / IE and / or a Release 17 capability field / IE for mTRP operation in 3GPP specification 38.306 or 38.331 v17.1.0 or later). In some implementations, the base station 104 determines, based on the at least one first capability, DL configuration parameters configured for DL ​​communication with the base station 104 via the TRP 107-2. In some implementations, the base station 104 determines, based on the at least one first capability, UL configuration parameters for UL communication with the base station 104 via the TRP 107-2. In the case where the base station 104 includes the DU 174 and the CU 172, the DU 174 makes the determination.

[0082] In some implementations, one or more capabilities include at least one second capability. In some such implementations, at least one second capability indicates that UE 102 supports multiple UL transmission timings for mTRP operation with a serving cell (i.e., operation of two or more TAs). In another implementation, at least one second capability indicates that UE 102 supports multiple UL transmission timings (for mTRP operation) with a serving cell and a non-serving cell. The physical cell index (PCI) of the non-serving cell is different from the PCI of the serving cell. In some implementations, at least one second capability includes the number of UL transmission timings (for mTRP operation) supported by UE 102 with a serving cell and / or across all serving cells configured / activated for UE 102. In another implementation, at least one second capability does not include the number of UL transmission timings (for mTRP operation) and indicates that UE 102 supports a default number (e.g., 2) of UL transmission timings. In some implementations, base station 104 determines the UL configuration parameters configured for UL communication with base station 104 via TRP 107-2 based on at least one second capability. In the case where the base station 104 includes the DU 174 and the CU 172, the DU 174 makes the determination.

[0083] In some implementations, the base station 104 receives one or more capabilities from the UE 102 after receiving the RRC setup complete message or performing a security activation procedure with the UE 102. In some implementations, the base station 104 sends a UE capability query message (e.g., a UECapabilityEnquiry message) to the UE 102, and in response, receives a UE capability information message (e.g., a UECapabilityInformation message) including one or more capabilities from the UE.

[0084] In other implementations, base station 104 receives a CN to BS message including one or more capabilities from CN 110 (e.g., after receiving the RRC setup complete message). In some implementations, base station 104 sends a BS to CN message to CN 110 after receiving the RRC setup complete message, and CN 110 sends a CN to BS message after receiving the BS to CN message (e.g., in response to receiving the BS to CN message). In some implementations, UE 102 sends a NAS message (e.g., a registration request message or a registration complete message) including a capability ID identifying one or more capabilities to CN 110, and CN 110 obtains the one or more capabilities from the capability ID. In other implementations, UE 102 performs a registration procedure with CN 110 via a base station (e.g., base station 104 or 106) prior to event 502 to register with CN 110. During the registration process, UE 102 receives a UE capability query message (e.g., UECapabilityEnquiry message) from the base station and sends a UE capability information message (e.g., UECapabilityInformation message) including one or more capabilities to the base station. The base station sends a BS to CN message including one or more capabilities to CN 110, and CN 110 stores the one or more capabilities. In some implementations, the CN to BS message and the BS to CN message are NG Application Protocol (NGAP) messages. In the case where the base station 104 includes a DU 174 and a CU 172, the CU 172 sends a CU to DU message including one or more capabilities to the DU 174. In some implementations, the CU to DU message can be an F1 Application Protocol (F1AP) message.

[0085] In some implementations, the base station 104 may include random access configuration parameters in the RRC reconfiguration message for the UE 102 to perform 598 a random access procedure. In some implementations, the random access configuration parameters are dedicated to the UE 102. For example, the base station 104 generates a RACH configuration (e.g., a RACH-ConfigDedicated, RACH-ConfigDedicated-r18, or RACH-Config Dedicated-v1800 IE) that includes the random access configuration parameters dedicated to the UE 102. In some implementations, the format of the RRCReconfiguration message includes a ReconfigurationWithSync IE, and the ReconfigurationWithSync IE includes a RACH-ConfigDedicated IE (e.g., a RACH configuration or includes a random access configuration parameter) (e.g., as specified in 3GPP specification 38.331 v17.0.0 or later). In the case where the RRC reconfiguration message is an RRCReconfiguration message, the base station 104 includes the RACH configuration or random access configuration parameters of the RRCReconfiguration message in the RRCReconfiguration message without including the ReconfigurationWithSync IE and encapsulating the RACH configuration or random access configuration parameters in the ReconfigurationWithSync IE. If the base station 104 uses the Reconfiguration WithSync IE to include the random access configuration parameters, the ReconfigurationWithSync IE causes the UE 102 to perform a handover, which causes an interruption of communication between the UE 102 and the base station 104. In other implementations, the base station 104 avoids including the random access configuration parameters in the RRC reconfiguration message.

[0086] In some implementations, the base station 104 indicates in the RRC reconfiguration message that UL synchronization is required (i.e., for communication with the base station 104 via the second TRP). That is, the base station 104 configures the UE 102 to obtain the (second) UL synchronization for communication between the UE 102 and the TRP 107-1 while maintaining the first UL synchronization for communication between the UE 102 and the TRP 107-2. In other words, the base station 104 configures the UE to maintain two TA values ​​for communication between the UE 102 and the base station 104 (e.g., between the UE 102 and the TRP 107-1 and between the UE 102 and the TRP 107-2, respectively). In another implementation, the base station 104 includes in the RRC reconfiguration message a configuration (e.g., a field or IE (e.g., an RRC version 18 field or IE)) indicating that UL synchronization is required for communication between the UE 102 and the TRP 107-2. In other words, the configuration implements operation of two TA values ​​for communication between UE 102 and base station 104 (e.g., between UE 102 and TRP 107-1 and between UE 102 and TRP 107-2, respectively).

[0087] In some implementations, the UE 102 initiates a random access procedure 598 in response to receiving the field or IE, and then sends an UL transmission (e.g., a channel state information (CSI) report, a sounding reference signal (SRS), a PUCCH transmission, and / or a PUSCH transmission) to the base station via TRP 107-2. In some such implementations, if the RRC reconfiguration message does not include the field or IE, the UE 102 does not initiate a random access procedure and sends an UL transmission to the base station via TRP 107-2. In another implementation, the UE 102 avoids sending an UL transmission to the base station via TRP 107-2 in response to receiving the field or IE. In some such cases, the UE 102 does not send a random access preamble to the base station 104 via TRP 107-2 until a PDCCH command (e.g., events 558, 560, 559, 561) is received from the base station.

[0088] Blocks 548, 550, 552, 554, and 556 are Figure 5A Collectively referred to as TRP configuration process 596A.

[0089] In some implementations, after receiving the RRC reconfiguration message at event 538, after performing the CSI resource configuration and CSI reporting process 594, or after performing the TRP configuration process 596A with the base station 104, the UE 102 receives 562, 564 RS from the base station 104 via the TRP 107-2. Depending on the implementation, the RS is configured in the CSI resource configuration at event 538, and events 562, 564 occur after receiving the RRC reconfiguration message at event 538, during or after the CSI resource configuration and CSI reporting process 594, or during or after the TRP configuration process 596A. After performing the TRP configuration process 596A with the base station 104, the UE 102 initiates 598 a random access procedure. In response to initiating the random access procedure, the UE 102 sends 566, 568 a second random access preamble to the base station 104 via the TRP 107-2 on the time / frequency resources and random access channel (RACH) opportunity. In response to the second random access preamble, the base station 104 sends 570, 572 a second random access response to the UE 102 via the TRP 107-2. The base station 104 includes the second preamble ID and the second TA command in the second random access response. The second preamble ID identifies the second random access preamble, and the second TA command includes a second TA value. The UE applies the second TA value and determines or maintains 574 an uplink synchronized with the TRP 107-2 after applying the second TA value (e.g., in response to applying the second TA value). The UE 102 applies the second TA value to send UL transmissions (e.g., PUCCH transmissions, PUSCH transmissions, and / or SRS transmissions) until the UE 102 receives a new or different TA value that updates the second TA value from the base station 104. In some implementations, the UE 102 starts a second TAT after or upon receiving the second TA command to maintain or manage a UL synchronization state with the TRP 107-2 or the base station 104. In some implementations, the base station 104 includes a UL grant (e.g., a RAR grant) in the second random access response, and the UE 102 sends a UL MAC PDU to the base station 104 via TRP 107-2 according to the UL grant. In the case where the random access procedure is a contention-based random access procedure, the UE 102 includes the C-RNTI of the UE 102 in the UL MAC PDU. The base station 104 identifies the UE 102 based on the C-RNTI. In response to the identification, the base station 104 generates a DCI and a CRC for the DCI, scrambles the CRC with the C-RNTI, and sends the DCI and the scrambled CRC to the UE 102 on the PDCCH. In some implementations, the DCI includes a UL grant. Upon receiving the DCI and the scrambled CRC on the PDCCH, the UE 102 determines that the content-based random access procedure 598 is successfully performed.In the case where the random access procedure 598 is a contention-free random access procedure, the UE 102 determines that the content-based random access procedure 598 is successfully performed in response to receiving the second random access response message.

[0090] In some implementations, the base station 104 starts a second TAT to maintain second UL synchronization of UL and / or DL ​​communications with the UE 102 via the TRP 107-2 after sending the second TA command to the UE 102 (e.g., in response to sending the second TA command to the UE 102). In some implementations, the TRP 107-1 generates timing information for a second random access preamble received from the UE 102 and sends the timing information to the base station 104. As an example, the timing information indicates a propagation delay or a propagation delay shift. Based on the timing information received from the TRP 107-2, the base station 104 determines a second TA value.

[0091] Boxes 566, 568, 570, 572, and 574 are Figure 5A are collectively referred to as random access process 598.

[0092] In some implementations, the UE 102 suspends communications (e.g., reception of DL channels / RSs or transmission of UL channels / RSs) with the base station 104 via the TRP 107-1 while performing the random access procedure 598. Depending on the implementation, the UE 102 does so if it cannot simultaneously perform the random access procedure based on one UL beam or RS (i.e., toward one TRP) and communicate UL and DL transmissions based on another UL beam or RS (i.e., toward another TRP) (i.e., independent of the random access procedure). In other implementations, the UE 102 continues to communicate with the base station 104 via the TRP 107-2 while performing the random access procedure 598. After successfully completing 598 the random access procedure, the UE performs 576 DL and UL communications with the base station via the TRP 107-1 and TRP 107-2 according to the first TA value and the second TA value, respectively.

[0093] In some implementations, at event 576, base station 104 and UE 102 use a HARQ entity (e.g., Figure 4A , Figure 4B or Figure 4C 107-2) to perform UL communications with base station 104 via TRP 107-1 and TRP 107-2. In some cases (e.g., for Figure 4BIn an example HARQ entity), the UL configuration parameters of events 548 and 550 include HARQ configuration parameters. The HARQ configuration parameters configure a first HARQ process ID set and a second HARQ process ID set. In some cases, the first HARQ process ID set and the second HARQ process ID set are for TRP 107-1 and TRP 107-2, respectively. The first HARQ process ID set and the second HARQ process ID set identify a first HARQ process set of the HARQ entity and a second HARQ process set of the HARQ entity, respectively. In some implementations, the first HARQ process ID set and the second HARQ process ID set are not the same. In other implementations, some HARQ process IDs of the first HARQ process ID set and the second HARQ process ID set are the same, while other HARQ process IDs are different.

[0094] In some implementations, the base station 104 sends one or more MAC CEs or DCIs to the UE 102 to change or update one or more HARQ process IDs in the first HARQ process ID set. In some other implementations, the base station 104 sends one or more MAC CEs or DCIs to the UE 102 to change or update one or more HARQ process IDs in the second HARQ process ID set. In some alternative implementations, the base station 104 does not configure the first HARQ process ID set and the second HARQ process ID set in the UL configuration parameters. In some implementations, the base station 104 determines the first HARQ process ID set and the second HARQ process ID set for mTRP operation based on preconfiguration. In another implementation, the first HARQ process ID set and the second HARQ process ID set are designated sets (e.g., as specified in the 3GPP specification). In yet another implementation, the base station 104 determines the first HARQ process ID set and the second HARQ process ID set based on a rule.

[0095] In some implementations, when the base station 104 determines to schedule the UE 102 to send an UL transmission to the TRP 107-1, the base station 104 selects a HARQ process ID from the first set of HARQ process IDs, and sends a DCI including an UL grant and the selected HARQ process ID to the UE 102. The UE 102 uses the HARQ process identified by the selected HARQ process ID, and uses the HARQ process and the UL grant to send the UL transmission to the base station 104. Similarly, when the base station 104 determines to schedule the UE 102 to send an UL transmission to the TRP 107-2, the base station 104 selects a HARQ process ID from the second set of HARQ process IDs, and sends a DCI including an UL grant and the selected HARQ process ID to the UE 102. The UE 102 uses the HARQ process identified by the selected HARQ process ID, and uses the HARQ process and the UL grant to send the UL transmission to the base station 104.

[0096] In some implementations, after receiving the RRC reconfiguration complete message at event 554, the base station 104 sends 558, 560 a PDCCH command to the UE 102 via TRP 107-2 to cause the UE 102 to initiate a random access procedure 598 with the base station 104 via TRP 107-2. In some implementations, the PDCCH command includes an RS index and a random access preamble index. Alternatively, the base station 104 sends the PDCCH command to the UE 102 via TRP 107-1. In response to the PDCCH command, at event 566, the UE 102 sends a random access preamble to the base station 104 via TRP 107-2. In some implementations, the random access preamble index includes a value of a second preamble ID that identifies a second random access preamble. Therefore, the UE 102 determines the second random access preamble based on the random access preamble index. In other implementations, the random access preamble index includes a value indicating or instructing the UE 102 to determine the random access preamble. Therefore, the UE 102 determines the second random access preamble by (randomly) selecting the second random access preamble from the random access preambles configured in the system information.

[0097] In some implementations, the PDCCH order is a DCI. The base station 104 generates a DCI and a CRC for the DCI, scrambles the CRC with a C-RNTI, and sends the DCI and the scrambled CRC to the TRP 107-2 (e.g., via an optical fiber connection). Then, the TRP 107-2 sends the DCI and the scrambled CRC to the UE 102 on the PDCCH. In some implementations, the base station 104 sends a first packet including the DCI and the scrambled CRC to the TRP 107-2. In some implementations, the base station 104 sends control information configuring or indicating time and / or frequency resources for the PDCCH to the TRP 107-2. In some implementations, the time and / or frequency resources include subcarriers, resource elements, or physical resource blocks. The TRP 107-2 sends the DCI and the scrambled CRC on the time and / or frequency resources according to the control information. In some implementations, the base station 104 includes the control information in the first packet. In other implementations, base station 104 sends a second packet including control information to TRP 107-2 instead of the first packet. In other implementations, base station 104 does not send control information for the DCI and the scrambled CRC to TRP 107-2. In such implementations, TRP 107-2 determines the time and / or frequency resources for the PDCCH and sends the DCI and the scrambled CRC on the time and / or frequency resources.

[0098] In some implementations, the RS index (e.g., SSB index) identifies one of the SSBs. In some such implementations, the base station 104 determines or decodes the SSB index indicated in the CSI report. In another implementation, the base station 104 determines or decodes the SSB index based on the radio resources (e.g., PUCCH resources) in which the base station 104 receives one of the CSI reports for the SSB. In some such implementations, the base station 104 configures different radio resources for the UE 102 to send CSI reports for each of the SSBs. In some examples, the base station 104 includes in the RRC reconfiguration message of event 536 a configuration to configure different radio resources (e.g., PUCCH resources) for the UE 102 to send CSI reports for each of the SSBs. In some implementations, the UE 102 determines the time / frequency resources and / or RACH timing based on the SSB (e.g., indicated in the RS index) and the random access configuration parameters received in the system information, and sends the second random access preamble on the time / frequency resources and / or RACH timing. In other implementations, the UE 102 determines the time / frequency resources and / or RACH timing based on the SSB (e.g., indicated in the RS index) and the random access configuration parameters received in the RRC reconfiguration message of event 550, and sends the second random access preamble on the time / frequency resources and / or RACH timing.

[0099] In other implementations, the RS index (e.g., CSI-RS index) identifies one of the CSI-RSs. In some implementations, the base station 104 determines the CSI-RS index indicated in the CSI report or decodes the CSI-RS index. In another implementation, the base station 104 determines the CSI-RS index or decodes the CSI-RS index based on the radio resources (e.g., PUCCH resources) in which the base station 104 receives the CSI report for the CSI-RS. In some such implementations, the base station 104 configures different radio resources for the UE 102 to send CSI reports for each of the CSI-RSs. In some examples, the base station 104 includes in the RRC reconfiguration message of event 536 a configuration to configure different radio resources (e.g., PUCCH resources) for the UE 102 to send CSI reports for each of the CSI-RSs. In some implementations, UE 102 determines the time / frequency resources and / or RACH opportunities based on the CSI-RS (e.g., indicated in the RS index) and random access configuration parameters in the RRC reconfiguration message received by UE 102 at event 550. UE 102 sends a second random access preamble on the time / frequency resources and / or RACH opportunities. In some implementations, the random access configuration parameters indicate one or more associations between the CSI-RS and the RACH opportunities and / or the time / frequency resources.

[0100] In some implementations, UE 102 determines transmission characteristics (e.g., spatial transmission filters / parameters) based on or by reference to the RS index in the PDCCH order, and uses the determined transmission characteristics to send a second random access preamble to TRP 107-2. In some examples, UE 102 uses reception characteristics for receiving 564 RS identified by the RS index to derive transmission characteristics. In some implementations, the transmission characteristics include phase, power and / or transmission precoder. In some implementations, UE 102 also uses DL and / or UL configuration parameters of event 550 to determine the transmission characteristics. In other implementations, UE 102 uses configuration parameters in the system information of event 510 to determine the transmission characteristics. In some implementations, UE 102 does not determine transmission characteristics (e.g., spatial transmission filters / parameters) based on or by reference to the RS index in the PDCCH order, and uses the determined transmission characteristics to send a second random access preamble to TRP 107-2.

[0101] In some implementations, UE 102 initiates 598 a random access procedure in response to random access configuration parameters received at event 550 and after receiving the RS at event 564. In such implementations, base station 104 does not send a PDCCH order to cause UE 102 to perform random access procedure 598.

[0102] In some implementations, the RRC reconfiguration message of event 550 includes configuration parameters (e.g., for PDCCH configuration, search space configuration, and / or control resource set (CORESET) configuration) for UE 102 to receive DL transmissions from TRP 107-2. In some implementations, UE 102 receives a second random access response according to the configuration parameters. In other implementations, the system information of event 510 includes configuration parameters for UE 102 to receive a random access response from TRP 107-2. In such implementations, UE 102 receives a second random access response according to the configuration parameters. In some implementations, UE 102 receives a second random access response from TRP 107-2 using a reception characteristic 564 for receiving RS.

[0103] Although TRP 107-2 is used in scenario 500A, the above description may be applied to a scenario in which TRP 107-3 is used instead of TRP 107-2. In this scenario, after successfully completing a random access procedure (similar to process 598) with the base station via TRP 107-3 and cell 125, the UE performs DL and UL communications with the base station via TRP 107-1 and TRP 107-3 according to the first TA value and the second TA value, respectively.

[0104] In some scenarios or implementations, the base station 104 sends a third TA command including a first new TA value to the UE 102 via TRP 107-1 or TRP 107-2 to update the first TA value. In some implementations, the third TA command is a MAC control element (CE). In response to receiving the third TA command, the UE 102 applies the first new TA value to the first UL synchronization and restarts the first TAT of the UE 102. The base station 104 restarts the first TAT of the base station 104 in response to sending the third TA command. In some scenarios or implementations, the base station 104 sends a fourth TA command including a second new TA value to the UE 102 via TRP 107-1 or TRP 107-2 to update the second TA value. In some implementations, the fourth TA command is a MAC CE. In response to receiving the fourth TA command, the UE 102 applies the second new TA value to the second UL synchronization and restarts the second TAT. In some scenarios or implementations, the base station 104 sends a single TA command including the first new TA value and the second new TA value to the UE 102 via the TRP 107-1 or the TRP 107-2 to update the first TA value and the second TA value, respectively. In some implementations, the single TA command is a new or existing MAC control element (CE) (e.g., as defined in 3GPP specification 38.321 V17.1.0).

[0105] In some implementations, TRP 107-1 generates timing information based on UL transmissions received from UE 102 and sends the timing information to base station 104. In some examples, the timing information indicates a propagation delay or a propagation delay shift. Based on the timing information received from TRP 107-1, base station 104 determines whether to update the first TA value. In some implementations, if the propagation delay or the propagation delay shift is greater than or equal to a first threshold, base station 104 determines to update the first TA value. Otherwise, if the propagation delay or the propagation delay shift is less than a second threshold, base station 104 determines not to update the first TA value. In some implementations, if base station 104 determines to update the first TA value, base station 104 generates a first new TA value. In some implementations, TRP 107-2 generates timing information based on UL transmissions received from UE 102 and sends the timing information to base station 104. In some examples, the timing information indicates a propagation delay or a propagation delay shift. Based on the timing information received from TRP 107-2, base station 104 determines whether to update the second TA value. In some implementations, if the propagation delay or propagation delay shift is greater than or equal to the third threshold, base station 104 determines to update the second TA value. Otherwise, if the propagation delay or propagation delay shift is less than the fourth threshold, base station 104 determines not to update the first TA value. In some implementations, if base station 104 determines to update the second TA value, base station 104 generates a second new TA value. Depending on the implementation, the first threshold, the second threshold, the third threshold, and the fourth threshold are the same or different.

[0106] Go to Figure 5B, scenario 500B is similar to scenario 500A, with the differences described below. In scenario 500B, base station 104 sends 549, 551 an RRC reconfiguration message to UE 102 via TRP 107-1, and the RRC reconfiguration message includes DL configuration parameters for DL ​​communication with base station 104 via TRP 107-2. In some implementations, base station 104 includes UL configuration parameters for UL communication with base station 104 via TRP 107-1 in the RRC reconfiguration message (e.g., to configure or enable DL communication with base station 104 via TRP 107-2). In some implementations, base station 104 includes the DL configuration parameters in a CellGroupConfig IE and includes the CellGroupConfig IE in the RRC reconfiguration message. In some implementations, base station 104 includes the DL configuration parameters in a BWP-DownlinkDedicated IE and includes the BWP-DownlinkDedicated IE in the RRC reconfiguration message. The RRC reconfiguration message of events 549, 551 is similar to the RRC reconfiguration message of events 548, 550, except that the base station 104 excludes or avoids including UL configuration parameters for UL communication with the base station 104 via TRP 107-2 in the RRC reconfiguration message of events 549, 551. Instead, the base station 104 sends 578, 580 another RRC reconfiguration message to the UE 102 via TRP107-1, and the RRC reconfiguration message includes UL configuration parameters for UL communication with the base station 104 via TRP107-2. In response, the UE 102 sends 582, 584 RRC reconfiguration complete messages to the base station 104 via TRP107-1. In some implementations, the base station 104 includes the UL configuration parameters in the CellGroupConfig IE and includes the CellGroupConfig IE in the RRC reconfiguration messages of events 578, 580. In some implementations, the base station 104 includes the UL configuration parameters in a BWP-UplinkDedicated IE and includes the BWP-UplinkDedicated IE in the RRC reconfiguration message.

[0107] Boxes 549, 551, 552, 554, 556, 578, 580, 582, and 584 are Figure 5B596B. After receiving the RRC reconfiguration message at event 538, performing the CSI resource configuration and CSI reporting process 594, or performing the TRP configuration process 596B with the base station 104, the UE 102 receives 562, 564 RS from the base station 104 via TRP 107-2. After performing the TRP configuration process 596A with the base station 104, the UE 102 performs 598 a random access process with the base station 104 via TRP 107-2.

[0108] Next reference Figure 5C , scenario 500C is similar to scenarios 500A and 500B, with the differences described below.

[0109] After sending 549, 550 the RRC reconfiguration message or receiving 552, 554 the RRC reconfiguration complete message, the base station 104 sends 579, 581 another RRC reconfiguration message to the UE 102 via TRP 107-2, the RRC reconfiguration message including UL configuration parameters for UL communication with the base station 104 via TRP 107-2. The RRC reconfiguration messages of events 579, 581 are similar to the RRC reconfiguration messages of events 578, 580, except that the base station 104 sends 579, 581 the RRC reconfiguration to the UE 102 via TRP 107-2 instead of TRP 107-1.

[0110] Boxes 549, 551, 552, 554, 556, 579, 581, 582, and 584 are Figure 5C Collectively referred to as TRP configuration process 596C.

[0111] Next reference Figure 5D , scenario 500D is similar to scenarios 500A, 500B, and 500C, with the differences described below.

[0112] After UE 102 performs a TRP configuration procedure 596A, 596B, or 596C with base station 104, UE 102 initiates 599 a random access procedure. In response to the initiation, UE 102 sends 566, 568 a second random access preamble to base station 104 via TRP 107-2. In response, base station 104 sends 571, 573 a second random access response to UE 102 via TRP 107-1 instead of TRP 107-2.

[0113] Next reference Figure 5E , scenario 500E is similar to scenarios 500A, 500B, 500C, and 500D, with the differences described below.

[0114] In some implementations, after receiving the RRC reconfiguration complete message at event 554, base station 104 sends 559, 561 a PDCCH command to UE 102 via TRP 107-1 to cause UE 102 to initiate a random access procedure 598 or 599 with base station 104 via TRP 107-2, similar to events 558, 560.

[0115] Figures 6 to 14 is a flow chart depicting an example method that a UE (e.g., UE 102) may implement to enable multiple TA value operations in a multi-TRP scenario. Figures 6 to 14 Some methods are shown in which the UE determines an action when one of multiple TATs expires and maintains multiple TA values. In some implementations, for example, the first TRP and the second TRP described below are TRP 107-1 and TRP 107-2. In another example, the first TRP and the second TRP described below are TRP 107-1 and TRP 107-3.

[0116] Some general descriptions are given below that may be applied to the following flow charts and / or embodiments.

[0117] In some implementations, the UE performs DL reception from a first TRP (e.g., one of TRP 107-1, TRP 107-2, TRP 107-3, TRP 108-1, and / or TRP 108-2) and / or UL transmission to the first TRP. In some such implementations, the UE performs DL reception from a second TRP (e.g., one of TRP 107-1, TRP 107-2, TRP 107-3, TRP 108-1, and / or TRP 108-2) and / or UL transmission to the second TRP. In some implementations, the first TRP is located in a serving cell. In other implementations, the second TRP is located in a serving cell. Alternatively, the second TRP is located in a neighboring cell. In some implementations, the second TRP is located in a neighboring cell or a non-serving cell, wherein the neighboring cell or non-serving cell is a cell having a PCI different from the PCI of the serving cell.

[0118] In some implementations, each TRP (e.g., TRP 107-1, TRP 107-2, TRP 107-3, TRP 108-1, and / or TRP 108-2) is associated with or identified by a TRP identifier. In some implementations, a base station (e.g., base station 104 or 106) includes the TRP identifier in a UL configuration that the base station sends to a UE (e.g., UE 102) for UL transmissions via the TRP identified by the TRP identifier. In some implementations, the UL configuration includes a DCI sent on a PDCCH, and / or a PUSCH configuration, a PUCCH configuration, and / or an SRS configuration included in an RRC message (e.g., an RRC reconfiguration message or an RRC recovery message) sent by the base station to the UE. In some implementations, the UL transmission includes a PUSCH transmission, a PUCCH transmission, and / or an SRS transmission. In some implementations, the base station includes the TRP identifier in a DL configuration that the base station sends to the UE 102 for DL ​​transmission via the TRP identified by the TRP identifier. In some implementations, the DL configuration includes a DCI sent on the PDCCH, and / or a CSI resource configuration, a PDSCH configuration, and / or a PDCCH configuration included in an RRC message (e.g., an RRC reconfiguration message or an RRC recovery message) sent by the base station to the UE. In some implementations, the DL transmission includes a CSI-RS transmission, an SSB transmission, a PDSCH transmission, and / or a PDCCH transmission.

[0119] In other implementations, the base station does not send a TRP identifier to the UE, and uses an implicit indication to indicate the TRP to the UE. In some implementations, the implicit indication is one of the following configuration parameters: CORESETPoolIndex, a value or value candidate for CORESETPoolIndex, dataScramblingIdentityPDSCH, dataScramblingIdentityPDSCH2-r16, or PUCCH-ResourceGroup-r16. In such implementations, the UE derives the TRP (identifier) ​​from the implicit indication. In some implementations, the base station sends an RRC message (e.g., an RRC reconfiguration message or an RRC recovery message) including the configuration parameters to the UE.

[0120] In some implementations, the base station configures or indicates a first TRP identifier to the UE. In some implementations, the UE derives the first TRP identifier and / or identifier value. In some implementations, the base station configures or indicates a second TRP identifier and / or identifier value to the UE. In some implementations, the UE derives the second TRP identifier and / or identifier value.

[0121] In some cases, the UE maintains multiple TA values. In some such implementations, the UE maintains multiple TA values, wherein all of the multiple TA values ​​are indicated or signaled to the UE. In other such implementations, the UE maintains multiple TA values, wherein all of the multiple TA values ​​are derived by the UE. In some implementations, the UE maintains multiple TA values, wherein at least one of some of the TA values ​​is indicated or signaled to the UE, and at least one of the remaining TA values ​​is derived by the UE. In other implementations, the UE maintains or operates multiple TA values ​​in a serving cell. In some implementations, the base station indicates or configures corresponding IDs for multiple TA values ​​to the UE. In some implementations, the UE derives corresponding IDs for multiple TA values. In some such implementations, each of the multiple TA values ​​has a separate ID. In some such cases, the UE maintains multiple TA values ​​for a serving cell or in a serving cell.

[0122] In some cases, the base station configures or activates a first serving cell set for the UE. In some cases, the base station configures or activates a second serving cell set for the UE. In some implementations, the first serving cell set has the same serving cell elements as the second serving cell set. In some implementations, the first serving cell set has different serving cell elements than the second serving cell set.

[0123] In some cases, the base station configures or activates a third serving cell set for the UE. In some implementations, the third serving cell set includes at least the first serving cell set. In another implementation, the third serving cell set includes at least the second serving cell set. In some implementations, the third serving cell set includes at least the first serving cell set and the second serving cell set. In some implementations, the third serving cell set is the union of the first serving cell set and the second serving cell set. In some implementations, the third serving cell set is the intersection of the first serving cell set and the second serving cell set.

[0124] In some cases, the UE may maintain a first TA value among multiple TA values. In some cases, the UE may maintain a second TA value among multiple TA values. In some implementations, the first TA value may be associated with a first TRP. In some implementations, the second TA value may be associated with a second TRP.

[0125] Depending on the implementation, the first TA value: (i) applies to or is associated with the first service cell set, (ii) applies to or is associated with the first TRP, (iii) applies to or is associated with a UL channel / RS transmission sent to the first TRP, and / or (iv) applies to or is associated with a UL channel / RS transmission associated with a first TRP identifier and / or identifier value.

[0126] Depending on the implementation, the second TA value: (i) applies to or is associated with a second set of service cells, (ii) applies to or is associated with a second TRP, (iii) applies to or is associated with a UL channel / RS transmission sent to the second TRP, and / or (iv) applies to or is associated with a UL channel / RS transmission associated with a second TRP identifier and / or identifier value.

[0127] In some cases, the base station indicates or configures an ID of a first TA value for the UE. In some cases, the UE derives an ID of the first TA value. In some cases, the base station indicates or configures an ID of a second TA value for the UE. In some cases, the UE derives an ID of the second TA value.

[0128] In some cases, the base station configures or indicates one or more TA groups for the UE. In some implementations, a TA group (TAG) includes or is associated with one or more serving cells and / or indices. In some implementations, each serving cell included in the same TAG or associated with the same TAG uses one or more TA values ​​or operates with one or more TA values. In some implementations, a TAG includes or is associated with one or more TA values. In some implementations, the corresponding IDs for one or more TA groups are indicated or configured to the UE, or the UE derives the corresponding IDs for one or more TA groups. In some such implementations, each TAG has a separate ID.

[0129] In some cases, the base station configures or indicates the first TAG for the UE. In some implementations, the first TAG is in one or more TA groups. In some implementations, the first TA value or the ID of the first TA value is associated with the first TAG or is included in the first TAG.

[0130] In some cases, the base station configures or indicates the second TAG for the UE. In some implementations, the second TAG is in one or more TA groups. In some implementations, the second TA value or the ID of the second TA value is associated with the second TAG or is included in the second TAG.

[0131] In some cases, the first TA value and the second TA value are associated with or included in the same TAG.

[0132] In some implementations, the first TAG is associated with a first TRP or a first TRP identifier and / or an identifier value. In some implementations, the first TAG includes a first service cell set or is associated with a first service cell set. In some implementations, the first service cell set is configured with a first TRP or a first TRP identifier and / or an identifier value, or is associated with a first TRP or a first TRP identifier and / or an identifier value. In some implementations, in each service cell in the first service cell set, at least one CORESET is configured with CORESETPoolIndex#0 or is associated with CORESETPoolIndex#0.

[0133] In some implementations, the first TAG includes or is associated with one or more TA values, wherein the one or more TA values: (i) are applicable to or are associated with a first set of service cells, (ii) are applicable to or are associated with a first TRP, (iii) are applicable to or are associated with a UL channel / RS transmission associated with the first TRP or a first TRP identifier and / or identifier value, and / or (iv) are applicable to or are associated with a third set of service cells.

[0134] In some implementations, the second TAG is associated with a second TRP or a second TRP identifier and / or an identifier value. In some implementations, the second TAG includes a second service cell set or is associated with a second service cell set. In some implementations, the second service cell set is configured with a second TRP or a second TRP identifier and / or an identifier value, or is associated with a second TRP or a second TRP identifier and / or an identifier value. In some implementations, in each service cell in the second service cell set, at least one CORESET is configured with CORESETPoolIndex#1 or is associated with CORESETPoolIndex#1.

[0135] In some implementations, the second TAG includes or is associated with one or more TA values, wherein the one or more TA values: (i) are applicable to or are associated with a second set of service cells, (ii) are applicable to or are associated with a second TRP, (iii) are applicable to or are associated with a UL channel / RS transmission associated with a second TRP or a second RP identifier and / or identifier value, and / or (iv) are applicable to or are associated with a third set of service cells.

[0136] In some cases, the base station indicates or configures the ID of the first TAG for the UE. In some cases, the UE derives the ID of the first TAG. In some cases, the base station indicates or configures the ID of the second TAG for the UE. In some cases, the UE derives the ID of the second TAG.

[0137] In some cases, the base station indicates or configures the third TAG for the UE. In some implementations, the third TAG is in one or more TA groups. In some implementations, the ID of the third TAG has been indicated or configured to the UE, or the UE can derive the ID of the third TAG.

[0138] In some implementations, the third TAG is associated with the first TRP or the first TRP identifier and / or identifier value. In some implementations, the third TAG is associated with the second TRP or the second TRP identifier and / or identifier value. In some implementations, the third TAG includes or is associated with the third service cell set.

[0139] In some implementations, the third TAG includes or is associated with one or more TA values. In some implementations, the third TAG includes or is associated with one or more TA values, wherein the one or more TA values ​​include the first TA value and / or the second TA value.

[0140] In some implementations, if the base station indicates or configures a third TAG for the UE, the UE determines that at least one of the following is expected: (i) a multi-TRP (M-TRP) mode is configured by the base station to all service cells included in or associated with the third TAG (for example, the M-TRP mode is a single DCI (S-DCI) M-TRP mode or a multi-DCI (M-DCI) M-TRP mode), (ii) the base station configures CORESETPoolIndex to all service cells included in or associated with the third TAG, and / or (iii) the base station configures a first TRP identifier and / or identifier value and a second TRP identifier and / or identifier value to all service cells included in or associated with the third TAG, or all service cells are associated with the first TRP identifier and / or identifier value and the second TRP identifier and / or identifier value.

[0141] In some implementations, if the base station configures a third TAG for the UE, the base station performs one or some of the following: (i) configuring an M-TRP mode (for example, the M-TRP mode is an S-DCI M-TRP mode or an M-DCI M-TRP mode) for all service cells included in or associated with the third TAG, (ii) configuring CORESETPoolIndex for all service cells included in or associated with the third TAG, and / or (iii) configuring a first TRP identifier and / or value and a second TRP identifier and / or value for all service cells included in or associated with the third TAG, or associating all service cells with the first TRP identifier and / or value and the second TRP identifier and / or value.

[0142] In some cases, the base station configures or indicates one or more primary TAGs (PTAGs) for the UE. In some implementations, the base station configures or indicates two PTAGs for the UE. In some cases, the base station configures or indicates one or more secondary TAGs (STAGs) for the UE.

[0143] In some cases, the first TAG is a PTAG. In some implementations, the first serving cell set includes a primary cell (PCell) or a primary secondary cell (PSCell). In some implementations, the first TAG is a STAG. In some implementations, the first serving cell set does not include a PCell or a PSCell.

[0144] In some cases, the second TAG is a PTAG. In some implementations, the second serving cell set includes a PCell or a PSCell. In some implementations, the second TAG is a STAG. In some implementations, the second serving cell set does not include a PCell or a PSCell.

[0145] In some cases, the third TAG is a PTAG. In some implementations, the third serving cell set includes a PCell or a PSCell. In some implementations, the third TAG is a STAG. In some implementations, the third serving cell set does not include a PCell or a PSCell.

[0146] In some cases, the base station configures or indicates one or more time alignment timers (TATs) for the UE. In some implementations, one or more TATs are configured or indicated for an active BWP or in a serving cell. In some implementations, the base station configures or indicates a first TAT in an active BWP or in a serving cell for the UE. In some implementations, the base station configures or indicates a second TAT in an active BWP or in a serving cell for the UE. In some implementations, the UE maintains the first TAT. In some implementations, the UE maintains the second TAT. In some implementations, the base station similarly maintains the first TAT and / or the second TAT.

[0147] In some implementations, the first TAT is associated with a first TAG. In other implementations, the first TAT is associated with or applied to a first serving cell set. In some implementations, the second TAT is associated with a second TAG. In other implementations, the second TAT is associated with or applied to a second serving cell set.

[0148] In some implementations, the base station configures or indicates an ID of the first TAT to the UE. In other implementations, the UE derives the ID of the first TAT. In some implementations, the base station configures or indicates an ID of the second TAT to the UE. In other implementations, the UE derives the ID of the second TAT.

[0149] In some cases, the base station configures or indicates a third TAT in an active BWP or in a serving cell for the UE. In some implementations, the third TAT is associated with or applied to a third serving cell set. In some implementations, the UE maintains the third TAT. In some implementations, the base station similarly maintains the third TAT. In some implementations, the base station configures or indicates an ID of the third TAT for the UE. In another implementation, the UE derives the ID of the third TAT.

[0150] In some cases, the first TA value and the second TA value belong to the same TAG (e.g., the third TAG) or are associated with the same TAG. In some implementations, the ID of the first TA value and the ID of the second TA value are included in the same TAG (e.g., the third TAG). In some cases, the first TA value and the second TA value belong to different TAGs (e.g., the first TAG and the second TAG) or are associated with different TAGs. In some implementations, the ID of the first TA value and the ID of the second TA value are included in different TAGs (e.g., the first TAG and the second TAG).

[0151] In some cases, whether the first TA value expires and whether the second TA value expires are controlled by the same TAT (e.g., a third TAT) or are associated with the same TAT. In other cases, whether the first TA value expires and whether the second TA value expires are controlled by different TATs (e.g., a first TAT and a second TAT) or are associated with different TATs.

[0152] In some cases, whether the first TAG is uplink time-aligned and whether the second TAG is uplink time-aligned is controlled by the same TAT (e.g., a third TAT) or is associated with the same TAT. In other cases, whether the first TAG is uplink time-aligned and whether the second TAG is uplink time-aligned is controlled by different TATs (e.g., the first TAT and the second TAT) or is associated with different TATs.

[0153] In some cases, whether the first serving cell set is uplink time-aligned and whether the second serving cell set is uplink time-aligned is controlled by the same TAT (e.g., a third TAT) or is associated with the same TAT. In other cases, whether the first serving cell set is uplink time-aligned and whether the second serving cell set is uplink time-aligned is controlled by different TATs (e.g., the first TAT and the second TAT) or is associated with different TATs.

[0154] In some implementations, the base station configures a first TAG and a second TAG for the UE for UL transmission to the first TRP and the second TRP, respectively. In some implementations, the base station sends a first RRC message and a second RRC message including the first TAG configuration and the second TAG configuration to the UE to configure the first TAG and the second TAG, respectively. In some implementations, the first TAG configuration and the second TAG configuration include a first TAG ID and a second TAG ID to identify the first TAG and the second TAG, respectively. In some implementations, the first TAG configuration and the second TAG configuration include a timer value belonging to / for the first TAT and a timer value belonging to / for the second TAT for the first TAG and the second TAG, respectively. In some implementations, the first RRC message and the second RRC message are the same RRC message (e.g., the same instance) or different RRC messages (e.g., different instances or different types of RRC messages). In some implementations, the first RRC message and the second RRC message include RRC settings, RRC reconfiguration and / or RRC recovery messages. The UE associates the first TA value and the second TA value with the first TAG and the second TAG, respectively. In some implementations, the first TAG is associated with the first TRP or the first TRP identifier and / or identifier value. In some implementations, the first TAG is associated with a specific service cell operated by the first TRP and configured for the UE. In some implementations, the first TAG is associated with an additional service cell operated by the first TRP and configured for the UE. In some implementations, the base station indicates or configures the association in the first RRC message. In some implementations, the second TAG is associated with the second TRP or the second TRP identifier and / or identifier value. In some implementations, the second TAG is associated with a specific service cell or a non-service cell, and the base station indicates or configures the association in the second RRC message.

[0155] In other implementations, the base station configures a single TAG (e.g., a third TAG) for the UE for UL transmission to the first TRP and the second TRP. In some implementations, the base station sends a first RRC message (e.g., an RRC setup, an RRC reconfiguration, and / or an RRC recovery message) including a single TAG configuration to the UE to configure the TAG. In some implementations, the TAG configuration includes a single TAG ID for identifying the TAG. In some implementations, the TAG configuration includes a timer value belonging to / for the first TAT and a timer value belonging to / for the second. In another implementation, the TAG configuration includes a timer value belonging to / for the first TAT, and the base station sends a second RRC message (e.g., an RRC setup, an RRC reconfiguration, and / or an RRC recovery message) including a timer value for the second TAT. The UE associates the first TA value and the second TA value with the TAG. In some implementations, the TAG is associated with: (i) the first TRP or the first TRP identifier and / or identifier value, and (ii) the second TRP or the second TRP identifier. In some implementations, the TAG is associated with a specific service cell operated by a first TRP and configured for the UE. In some implementations, the TAG is associated with an additional service cell operated by a first TRP and configured for the UE. In some implementations, the base station indicates or configures the association in a first RRC message. In some implementations, the TAG is associated with a second TRP or a second TRP identifier and / or identifier value. In some implementations, the TAG is associated with a specific service cell or a non-service cell, and the base station indicates or configures the association in a second RRC message.

[0156] In some implementations, the base station configures a specific service cell to be associated with a first TRP or a first TRP identifier and / or identifier value. In some implementations, the base station configures a first control resource set (CORESET) associated with a specific service cell or a first TRP. In another implementation, the base station configures CORESETPoolIndex#0 to identify the first CORESET. In some implementations, the base station sends a third RRC message (e.g., an RRC setup message, an RRC reconfiguration message, or an RRC recovery message) to the UE that configures the first CORESET and / or includes CORESETPoolIndex#0. Therefore, the UE monitors the PDCCH on the first CORESET to receive DCI from the base station, which implies that the UE monitors the PDCCH or receives DCI from the base station (i.e., from the first TRP) via the first TRP. In some such cases, the UE determines that CORESETPoolIndex#0 indicates a specific TRP (i.e., the first TRP) of the base station.

[0157] In some implementations, the base station configures a specific serving cell to be associated with a second TRP or a second TRP identifier and / or an identifier value. In other implementations, the second TAG is associated with a non-serving cell, and the base station indicates or configures the association in a second RRC message. In some implementations, the base station configures a non-serving cell associated with a second TRP or a second TRP identifier and / or an identifier value. In some implementations, the base station configures the second CORESET to be associated with a specific serving cell, a non-serving cell, or a second TRP. In another implementation, the base station configures CORESETPoolIndex#1 to identify the second CORESET. In some implementations, the base station sends a third RRC message (e.g., an RRC setup message, an RRC reconfiguration message, or an RRC recovery message) to the UE configuring the second CORESET and / or including CORESETPoolIndex#1. Therefore, the UE monitors the PDCCH on the second CORESET to receive DCI from the base station, which implies that the UE monitors the PDCCH or receives DCI from the base station (i.e., from the first TRP) via the second TRP. In some such implementations, the UE determines that CORESETPoolIndex#1 indicates a specific TRP (ie, the second TRP).

[0158] In some implementations, in addition to the TAG ID described above, the base station also configures the UE with a first ID that identifies the first TA value. In some implementations, the base station includes the first ID in the RRC message described above. In another implementation, the base station includes the first ID in the first TA command. In other implementations, the UE derives or determines the first ID and associates the first ID with the first TA value. Similarly, in addition to the TAG ID described above, the base station also configures the UE with a second ID that identifies the second TA value. In some implementations, the base station includes the second ID in the RRC message described above. In another implementation, the base station includes the second ID in the second TA command. In other implementations, the UE derives or determines the second ID and associates the second ID with the second TA value.

[0159] More generally, in some implementations, the base station configures or indicates to the UE a first index for or associated with the first TRP. In some implementations, the UE derives or determines the first index. In some implementations, the first index is one of: (i) a first TRP identifier and / or identifier value, (ii) an ID of a first TAG, (iii) an ID of a first TA value, and / or (iv) an ID of a first TAT.

[0160] More generally, in another implementation, the base station configures or indicates to the UE a second index for or associated with the second TRP. In some implementations, the UE derives the second index. In some implementations, the second index is one of: (i) a second TRP identifier and / or identifier value, (ii) an ID of a second TAG, (iii) an ID of a second TA value, and / or (iv) an ID of a second TAT.

[0161] In some cases, the first TAT is started or restarted by the UE or the base station in response to at least one of the following: (i) the UE receives a timing advance command MAC CE, wherein the timing advance command MAC CE indicates or updates timing adjustment related information about the first TA value or the first TAG or the first TAT; (ii) the UE receives a timing advance command in a RAR response or in a MAC payload for a RAR response, wherein: (a) in some implementations, the RAR response or the timing advance command is sent by the first TRP or is associated with the first TRP, (b) in some implementations, the RAR response or the timing advance command is associated with the first index, and / or (c) in some implementations, the RAR response or the timing advance command indicates that the RAR response and / or the timing advance command is for the first TRP; and / or (iii) the UE receives a timing advance command in a MAC payload including a C-RNTI. An absolute timing advance command is received in a response to an MSGA transmission of a CE, wherein: (a) in some implementations, the response to the MSGA or the absolute timing advance command is sent by or associated with a first TRP, (b) in some implementations, the response to the MSGA or the absolute timing advance command is associated with a first index, and / or (c) in some implementations, the response to the MSGA or the absolute timing advance command indicates that the response is to the first TRP.

[0162] In some cases, the second TAT is started or restarted in response to at least one of the following: (i) the UE receives a timing advance command MAC CE, wherein in some implementations, the timing advance command MAC CE indicates or updates timing adjustment related information about a second TA value, a second TAG, or a second TAT; (ii) the UE receives a timing advance command in a RAR response or in a MAC payload for a RAR response, wherein: (a) in some implementations, the RAR response or the timing advance command may be sent by the second TRP or associated with the second TRP, (b) in some implementations, the RAR response or the timing advance command is associated with the second index, and / or (c) in some implementations, the RAR response or the timing advance command indicates that the RAR response or the timing advance command is for the second TRP; and / or (iii) the UE receives a timing advance command in a MAC payload including a C-RNTI. An absolute timing advance command is received in a response to an MSGA transmission of the CE, wherein: (a) in some implementations, the response to the MSGA or the absolute timing advance command is sent by or associated with a second TRP, (b) in some implementations, the response to the MSGA or the absolute timing advance command is associated with a second index, and / or (iii) in some implementations, the response to the MSGA or the absolute timing advance command indicates that the response is to the second TRP.

[0163] In some cases, the third TAT is initiated or restarted in response to at least one of the following: (i) the UE receives a timing advance command MAC CE, wherein in some implementations, the timing advance command MAC CE indicates or updates timing adjustment related information about at least one of the following: (a) a first TA value, a first TAG, or a first TAT; (b) a second TA value, a second TAG, or a second TAT; and / or (c) a third TA value, a third TAG, or a third TAT, (ii) the UE receives a timing advance command in a RAR response or in a MAC payload for a RAR response, wherein: (a) in some implementations, the RAR response or the timing advance command is sent by or associated with the first TRP and / or the second TRP, (b) in some implementations, the RAR response or the timing advance command is associated with the first index and / or the second index, and / or (c) in some implementations, the RAR response or the timing advance command indicates that the RAR response or the timing advance command is for the first TRP and / or the second TRP; and / or (iii) the UE receives a timing advance command in a RAR response or in a MAC payload for a RAR response, wherein: (a) in some implementations, the RAR response or the timing advance command is sent by or associated with the first TRP and / or the second TRP, (b) in some implementations, the RAR response or the timing advance command is associated with the first index and / or the second index, and / or (c) in some implementations, the RAR response or the timing advance command indicates that the RAR response or the timing advance command is for the first TRP and / or the second TRP; and / or An absolute timing advance command is received in a response to an MSGA transmission of a MAC CE, wherein: (a) in some implementations, the response to the MSGA or the absolute timing advance command is sent by or associated with the first TRP and / or the second TRP, (b) in some implementations, the response to the MSGA or the absolute timing advance command is associated with a first index and / or a second index, and / or (c) in some implementations, the response to the MSGA or the absolute timing advance command indicates that the response is for the first TRP and / or the second TRP.

[0164] First go to Figure 6 , an example method 600 for a UE (e.g., UE 102) to implement operations for performing multiple TA values ​​in a multi-TRP scenario.

[0165] Method 600 begins at block 602, where a UE performs DL and / or UL communications with a base station (e.g., events 504, 506, 508, 510, 512, 514, 516, 518, 590, 522, 524, 526, 528, 532, 534, 592, 536, 538, 540, 542, 544, 546, 594, 549, 551, 552, 554, 556, 562, 564). At block 604, the UE receives a configuration from the base station that enables operation of two TA values ​​(e.g., events 548, 550, 596A, 578, 580, 596B, 579, 581, 596C). At block 606, the UE receives a first TA value and a second TA value from the base station (e.g., events 516, 518, 570, 571, 572, 573, 590, 598, 599). At block 608, upon receiving the first TA value (e.g., upon receiving, after receiving, or in response to receiving), the UE starts or restarts the first TAT to maintain first UL synchronization with the base station. At block 610, upon receiving the second TA value, the UE starts or restarts the second TAT to maintain second UL synchronization with the base station. At block 611, the UE detects whether the first TAT or the second TAT expires. If the UE detects that the first TAT expires, the process proceeds to block 612. At block 612, the UE stops sending UL transmissions associated with the first TA value to the base station. If the UE detects that the second TAT expires, the process proceeds to block 614. At block 614, the UE stops sending UL transmissions associated with the second TA value to the base station.

[0166] When the first TAT expires and the UE stops transmitting to the first TRP, the UE may continue UL transmissions associated with the second TAT to the second TRP. Conversely, when the second TAT expires and the UE stops transmitting to the second TRP, the UE may continue UL transmissions associated with the first TAT to the first TRP. For example, in some implementations, the UE reports a loss of synchronization with the first TRP (e.g., TAT expiration) to the base station, and the base station stops scheduling transmissions to the first TRP but continues scheduling transmissions to the second TRP.

[0167] In some implementations, the UE maintains a first UL synchronization and a second UL synchronization with the base station based on the first TA value and the second TA value, respectively. In some implementations, the UE applies the first TA value and the second TA value to a first UL transmission and a second UL transmission with the base station on a serving cell, respectively. In other implementations, the UE applies the first TA value and the second TA value to send a first UL transmission and a second UL transmission with the base station on a serving cell and a non-serving cell, respectively.

[0168] In some implementations, the UE receives a first TA value in a first random access response, a first MAC CE, or a first MAC PDU from a base station. In some implementations, the UE receives a second TA value in a second random access response, a second MAC CE, or a second MAC PDU from a base station. In some implementations, the first MAC CE and the second MAC CE are the same MAC CE. In another implementation, the first MAC CE and the second MAC CE are different MAC CEs having the same MAC CE format or different MAC CE formats. In some implementations, the first MAC PDU and the second MAC PDU are the same MAC PDU. In another implementation, the first MAC PDU and the second MAC PDU are different MAC PDUs.

[0169] A more detailed description of elements of method 600 is described herein, particularly with respect to the general description above. For example, in some implementations: (i) the first TA value and the second TA value shown at block 606 are described in the description of the first TA value and the second TA value described in the general description above, and (ii) the first TAT and the second TAT shown at blocks 608 and 610 are described in the description of the first TAT and the second TAT described in the general description above.

[0170] Next go to Fig. 7A , an example method 700A in which a UE (e.g., UE 102) implements operations for performing multiple TA values ​​in a multi-TRP scenario.

[0171] Method 700A starts at block 702. Blocks 702, 704, 706, 708, 710, and 711A are similar to blocks 602, 604, 606, 608, 610, and 611. If the UE detects that a first TAT has expired, the flow proceeds to block 712A. At block 712A, the UE flushes HARQ buffers of a first HARQ process set, wherein the first HARQ process set is associated with a PUSCH transmission to which the UE applies a first TA value. If the UE detects that a second TAT has expired, the flow proceeds to block 714A. At block 714A, the UE flushes HARQ buffers of a second HARQ process set, wherein the second HARQ process set is associated with a PUSCH transmission to which the UE applies a second TA value.

[0172] Figure 7B Shows something like Fig. 7A Example method 700B for scenario 700A is shown, except that method 700B includes blocks 711B, 712B, and 714B, as described below.

[0173] At block 711B, the UE detects whether both the first TAT and the second TAT have expired. If the UE detects that both the first TAT and the second TAT have expired, the flow proceeds to block 712B. At block 712B, the UE flushes the HARQ buffers of the HARQ processes associated with the first PUSCH transmission and the second PUSCH transmission to which the UE applies the first TA value and the second TA value, respectively. If the UE does not detect that both the first TAT and the second TAT have expired, the flow proceeds to block 714B. At block 714B, the UE avoids flushing the HARQ buffers.

[0174] Similar to method 600 , a more detailed description of the elements of method 700 is generally detailed above.

[0175] In some cases, one or more HARQ processes in a serving cell are signaled or configured to the UE. In some implementations, one or more HARQ processes in each of the one or more serving cells are signaled or configured to the UE. For example, up to 16 HARQ processes in a serving cell are signaled or configured to the UE. As another example, up to 16 HARQ processes in each of the one or more serving cells are signaled or configured to the UE, so that up to 16 HARQ processes are signaled or configured to each of the serving cells.

[0176] In some cases, the first HARQ process set is signaled or configured to the UE. In some cases, the UE derives the first HARQ process set. In some implementations, the first HARQ process set in each service cell in the first service cell set is signaled or configured to the UE. In some implementations, the UE derives the first HARQ process set in each service cell in the first service cell set. In some implementations, some elements or ID numbers in each first HARQ process set in each service cell in the first service cell set are different. In another implementation, some elements or ID numbers in each first HARQ process set in each service cell in the first service cell set are the same. For example, when the first service cell set includes service cell #0 and service cell #1, for some such examples, the first HARQ process set in service cell #0 is: HARQ process #1, #2, and #5. However, the first HARQ process set in service cell #1 is: HARQ process #1, #5, and #9.

[0177] In some cases, the second HARQ process set is signaled or configured to the UE. In some cases, the UE may derive the second HARQ process set. In some implementations, the second HARQ process set in each serving cell in the second serving cell set is signaled or configured to the UE. In some implementations, the UE derives the second HARQ process set in each serving cell in the second serving cell set. In some implementations, some elements or ID numbers in each second HARQ process set in each serving cell in the second serving cell set are different. In some implementations, some elements or ID numbers in each second HARQ process set in each serving cell in the second serving cell set are the same. For example, when the second serving cell set includes serving cell #0 and serving cell #1, the second HARQ process set in serving cell #0 is: HARQ process #3, #6, and #11. However, the second HARQ process set in serving cell #1 is: HARQ process #2, #4, and #8.

[0178] In some implementations, at least in one serving cell, the elements in the first HARQ process set are orthogonal to those in the second HARQ process set. In some implementations, at least in one serving cell, each value of the HARQ process ID in the first HARQ process set is different from the value in the second HARQ process set. In some implementations, at least in one serving cell, none of the values ​​of the HARQ process ID in the first HARQ process set is the same as the value in the second HARQ process set. For example, when both the first serving cell set and the second serving cell set include serving cell #0 and serving cell #1, the first HARQ process set in serving cell #0 is: HARQ process #1, #2, and #5. However, the first HARQ process set in serving cell #1 is: HARQ process #1, #5, and #9. The second HARQ process set in serving cell #0 is: HARQ process #3, #6, and #11. However, the second HARQ process set in serving cell #1 is: HARQ process #2, #4, and #8.

[0179] In some cases, the first HARQ process set is associated with one of the candidate values ​​of the TRP identifier. In some implementations, the first HARQ process set is associated with one of the candidate values ​​of CORESETPoolIndex. In some implementations, the first HARQ process set is associated with CORESETPoolIndex#0. In other implementations, the first HARQ process set is associated with CORESETPoolIndex#1.

[0180] In some cases, the second HARQ process set is associated with one of the candidate values ​​of the TRP identifier. In some implementations, the second HARQ process set is associated with one of the candidate values ​​of CORESETPoolIndex. In some implementations, the second HARQ process set is associated with CORESETPoolIndex#1. In other implementations, the second HARQ process set is associated with CORESETPoolIndex#0.

[0181] In some cases, the first HARQ process set is associated with the first index. In other cases, the second HARQ process set is associated with the second index.

[0182] In some cases, for a HARQ process in a first HARQ process set, the HARQ process includes at least one of the following properties: (i) in some implementations, the HARQ process is used to send an UL transmission, wherein the UL transmission is sent via a spatial transmission filter / parameter derived from a spatial relationship, an UL / joint TCI state, or a source RS, wherein the spatial transmission filter / parameter is associated with or includes a first TA value; (ii) in some implementations, the HARQ process is used to send an UL transmission, wherein the UL transmission is sent using a first TA value; and / or (iii) in some implementations, the HARQ process is used to send an UL transmission, wherein the UL transmission is associated with or includes a first TA value.

[0183] In some cases, for a HARQ process in a second HARQ process set, the HARQ process includes at least one of the following properties: (i) in some implementations, the HARQ process is used to send an UL transmission, wherein the UL transmission is sent via a spatial transmission filter / parameter derived from a spatial relationship, an UL / joint TCI state, or a source RS, and the spatial transmission filter / parameter is associated with or includes a second TA value; (ii) the HARQ process is used to send an UL transmission, wherein the UL transmission is sent using a second TA value; and / or (iii) the HARQ process is used to send an UL transmission, wherein the transmission is associated with or includes a second TA value.

[0184] In some cases, the base station signals or configures a HARQ entity in a serving cell for the UE. In some implementations, the base station signals or configures only one HARQ entity in a serving cell for the UE. In some implementations, the base station signals or configures a HARQ entity in each serving cell in a first serving cell set for the UE. In some implementations, the base station signals or configures a HARQ entity in each serving cell in a second serving cell set for the UE. In some implementations, the base station signals or configures a HARQ entity in at least one serving cell in the first serving cell set for the UE. In some implementations, the base station signals or configures a HARQ entity in at least one serving cell in the second serving cell set for the UE. In some implementations, one HARQ entity is signaled or configured by the base station to one or more of each serving cell in the first serving cell set. In some implementations, one HARQ entity is signaled or configured by the base station to one or more of each serving cell in the second serving cell set.

[0185] In some implementations, the first HARQ process set may be included in or belong to a HARQ entity in the first serving cell. In some implementations, the second HARQ process set may be included in or belong to a HARQ entity in the first serving cell.

[0186] In some implementations, the first serving cell is associated with or included in a first serving cell set. In some implementations, the first serving cell is associated with or included in a second serving cell set. In some implementations, the first serving cell is associated with or included in a third serving cell set.

[0187] In some cases, the base station signals or configures more than one HARQ entity in a serving cell for the UE. In some implementations, the base station signals or configures more than one HARQ entity in each serving cell in the first serving cell set for the UE. In some implementations, the base station signals or configures more than one HARQ entity in each serving cell in the second serving cell set for the UE. In some implementations, the base station signals or configures more than one HARQ entity in at least one serving cell in the first serving cell set for the UE. In some implementations, the base station signals or configures more than one HARQ entity in at least one serving cell in the second serving cell set for the UE. In some implementations, more than one HARQ entity is signaled or configured to one or more of each serving cell in the first serving cell set. In some implementations, more than one HARQ entity is signaled or configured to one or more of each serving cell in the second serving cell set.

[0188] In some implementations, the base station signals or configures a first HARQ entity in a second serving cell for the UE. In some implementations, the base station signals or configures a second HARQ entity in a second serving cell for the UE.

[0189] In some implementations, the second serving cell is associated with or included in the first serving cell set. In some implementations, the second serving cell is associated with or included in the second serving cell set. In some implementations, the second serving cell is associated with or included in the third serving cell set.

[0190] In some implementations, the first HARQ entity is associated with a first TRP or a first TRP identifier and / or identifier value. In some implementations, the first HARQ entity includes a first TRP identifier and / or identifier value. For example, the first HARQ entity is associated with or includes CORESETPoolIndex#0. In some implementations, the first HARQ entity includes or is associated with a first HARQ process set.

[0191] In some implementations, the second HARQ entity is associated with a second TRP or a second TRP identifier and / or identifier value. In some implementations, the second HARQ entity includes a second TRP identifier and / or identifier value. For example, the second HARQ entity is associated with or includes CORESETPoolIndex#1. In some implementations, the second HARQ entity includes or is associated with a second HARQ process set.

[0192] In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the first HARQ process set. In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the first HARQ process set through at least one of DCI signaling, MAC-CE, or RRC signaling. In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the first HARQ process set via a bitmap. In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the first HARQ process set. In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the first HARQ process set through at least one of DCI signaling, MAC-CE, or RRC signaling. In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the first HARQ process set through a bitmap.

[0193] In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the second HARQ process set. In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the second HARQ process set by at least one of DCI signaling, MAC-CE, or RRC signaling. In some implementations, the base station indicates or signals the elements or HARQ process IDs included in the second HARQ process set by a bitmap. In some implementations, the base station updates or changes the elements or HARQ process IDs included in the second HARQ process set. In some implementations, the base station updates or changes the elements or HARQ process IDs included in the second HARQ process set by at least one of DCI signaling, MAC-CE, or RRC signaling. In some implementations, the base station updates or changes the elements or HARQ process IDs included in the second HARQ process set by a bitmap.

[0194] In some cases, if a UL transmission (e.g., UL data) is associated with a first TRP or a first TRP identifier and / or identifier value, the UL transmission is associated with or uses a HARQ process in a first HARQ process set.

[0195] In some cases, if a UL transmission (e.g., UL data) is associated with a second TRP or a second TRP identifier and / or identifier value, the UL transmission is associated with or uses a HARQ process in a second HARQ process set.

[0196] In some cases, the UE performs at least one of the following actions in response to expiration of the first TAT: (i) flushing or clearing a HARQ buffer belonging to or associated with the first HARQ process set, wherein: (a) in some implementations, the UE performs the action when the UE does not support retransmissions scheduled by a PDCCH received in a different CORESETPoolIndex than the CORESETPoolIndex of the initial transmission (e.g., for the same HARQ process ID, the UE does not expect to receive DCI from a different CORESETPoolIndex for scheduling retransmissions); (b) in some implementations, the UE performs the action when the UE reports supportRetx-Diff-CoresetPool-Multi-DCI-TRP-r16; and / or (c) in some implementations, the action is Refers to refreshing or clearing each HARQ process in the first HARQ process set belonging to the first serving cell set or the HARQ buffer associated with each HARQ process; (ii) not refreshing or clearing the HARQ buffer belonging to the second HARQ process set or the HARQ buffer associated with the second HARQ process set; (iii) not refreshing or clearing each HARQ process in the second HARQ process set belonging to the second serving cell set or the HARQ buffer associated with each HARQ process; (iv) not refreshing or clearing the HARQ process or the HARQ buffer associated with the HARQ process other than the first HARQ process set in the first serving cell and / or the second serving cell; and / or (v) not refreshing or clearing the HARQ process or the HARQ buffer associated with the HARQ process other than the first HARQ process set in the first serving cell set and / or the second serving cell set. In some such cases, the first TAG is a STAG. In some such cases, the first TA value belongs to a STAG or is associated with a STAG. In some such cases, the first TAT is associated with a STAG.

[0197] Alternatively, the UE performs at least one of the following actions in response to expiration of the first TAT: (i) refreshing or clearing the HARQ buffer belonging to the second HARQ process set or associated with the second HARQ process set, (ii) refreshing or clearing each HARQ process in the second HARQ process set belonging to the second serving cell set or the HARQ buffer associated with each HARQ process, (iii) refreshing or clearing the HARQ process belonging to the first serving cell and / or the second serving cell other than the first HARQ process set or the HARQ buffer associated with the HARQ process, (iv) refreshing or clearing the HARQ buffer belonging to the first serving cell and / or the second serving cell (v) refreshing or clearing all HARQ buffers in the first service cell set and / or the second service cell set, (vi) refreshing or clearing all HARQ buffers in the first service cell set and / or the second service cell set, (vii) refreshing or clearing all HARQ processes belonging to data related to the first index or all HARQ buffers associated with the HARQ processes in all service cells, and / or (viii) refreshing or clearing all HARQ buffers in all service cells. In some such cases, the first TAG is a PTAG. In some such cases, the first TA value belongs to a PTAG or is associated with a PTAG. In some such cases, the first TAT is associated with a PTAG.

[0198] In some cases, the UE performs at least one of the following actions in response to expiration of the second TAT: (i) flushing or clearing a HARQ buffer belonging to or associated with the second HARQ process set, wherein: (a) in some implementations, the UE performs the action when the UE does not support retransmissions scheduled by a PDCCH received in a different CORESETPoolIndex than the CORESETPoolIndex of the initial transmission (e.g., for the same HARQ process ID, the UE does not expect to receive DCI from a different CORESETPoolIndex for scheduling retransmissions); (b) in some implementations, the UE performs the action when the UE reports supportRetx-Diff-CoresetPool-Multi-DCI-TRP-r16; and / or (c) in some implementations, the action is Refers to refreshing or clearing each HARQ process in the second HARQ process set belonging to the second serving cell set or the HARQ buffer associated with each HARQ process; (ii) not refreshing or clearing the HARQ buffer belonging to the first HARQ process set or the HARQ buffer associated with the first HARQ process set; (iii) not refreshing or clearing each HARQ process in the first HARQ process set belonging to the first serving cell set or the HARQ buffer associated with each HARQ process; (iv) not refreshing or clearing the HARQ process belonging to the first serving cell and / or the second serving cell except the second HARQ process set or the HARQ buffer associated with the HARQ process; and / or (v) not refreshing or clearing the HARQ process belonging to the first serving cell set and / or the second serving cell except the second HARQ process set or the HARQ buffer associated with the HARQ process. In some such cases, the second TAG is a STAG. In some such cases, the second TA value may belong to a STAG or be associated with a STAG. In some such cases, the second TAT is associated with a STAG.

[0199] Alternatively, the UE performs at least one of the following actions in response to the expiration of the second TAT: (i) refreshing or clearing the HARQ buffer belonging to the first HARQ process set or associated with the first HARQ process set, (ii) refreshing or clearing each HARQ process in the first HARQ process set belonging to the first serving cell set or the HARQ buffer associated with each HARQ process, (iii) refreshing or clearing the HARQ process belonging to the first serving cell and / or the second serving cell except the second HARQ process set or the HARQ buffer associated with the HARQ process, (iv) refreshing or clearing the HARQ buffer belonging to the first serving cell set and / or the second serving cell except the second HARQ process set or the HARQ buffer associated with the HARQ process, (v) refreshing or clearing all HARQ buffers in the first service cell and / or the second service cell, (vi) refreshing or clearing all HARQ buffers in the first service cell set and / or the second service cell set, (vii) refreshing or clearing all HARQ processes in all service cells belonging to data related to the second TRP or the second TRP identifier and / or identifier value or all HARQ buffers associated with the HARQ processes, and / or (viii) refreshing or clearing all HARQ buffers in all service cells. In some such cases, the second TAG is a PTAG. In some such cases, the second TA value belongs to a PTAG or is associated with a PTAG. In some such cases, the second TAT is associated with a PTAG.

[0200] Next go to Fig. 8A , a UE (e.g., UE 102) implements example method 800A for performing operations on multiple TA values ​​in a multi-TRP scenario.

[0201] Method 800A starts at block 802. Blocks 802, 804, 806, 808, 810, and 811A are similar to blocks 602, 604, 606, 608, 610, and 611. If the UE detects that a first TAT has expired, the flow proceeds to block 812. At block 812, the UE clears a configured UL grant configured with and / or associated with the first TA value. If the UE detects that a second TAT has expired, the flow proceeds to block 814. At block 814, the UE clears a configured UL grant configured with and / or associated with the second TA value.

[0202] Figure 8B Shows something like Fig. 8A Example method 800B for scenario 800A is shown, except that method 800B includes blocks 811B, 813, and 815.

[0203] At block 811B, the UE detects whether the first TAT and the second TAT have expired. If the UE detects that the first TAT and the second TAT have expired, the process proceeds to block 813. At block 813, the UE performs the clearing actions described in blocks 812 and / or 814. If the UE does not detect that the first TAT and the second TAT have expired, the process proceeds to block 815. At block 815, the UE avoids performing the clearing actions described in blocks 812 and / or 814.

[0204] Next go to Fig.9A , an example method 900A in which a UE (e.g., UE 102) implements operations for performing multiple TA values ​​in a multi-TRP scenario.

[0205] Method 900A starts at block 902. Blocks 902, 904, 906, 908, 910, and 911A are similar to blocks 602, 604, 606, 608, 610, and 611. If the UE detects that a first TAT has expired, the flow proceeds to block 912. At block 912, the UE releases PUCCH resources and / or scheduling request resource configuration instances configured with and / or associated with a first TA value. If the UE detects that a second TAT has expired, the flow proceeds to block 914. At block 914, the UE releases PUCCH resources and / or scheduling request resource configuration instances configured with and / or associated with a second TA value.

[0206] Fig. 9B Shows something like Fig.9A The example method 900B for scenario 900A is shown, except that method 900B includes blocks 911B, 913, and 915.

[0207] At block 911B, the UE detects whether the first TAT and the second TAT have expired. If the UE detects that the first TAT and the second TAT have expired, the process proceeds to block 913. At block 913, the UE performs the release actions described in blocks 912 and / or 914. If the UE does not detect that the first TAT and the second TAT have expired, the process proceeds to block 915. At block 815, the UE avoids performing the release actions described in blocks 912 and / or 914.

[0208] Next go to Fig. 10A , an example method 1000A in which a UE (e.g., UE 102) implements operations for performing multiple TA values ​​in a multi-TRP scenario.

[0209] Method 1000A starts at block 1002. Blocks 1002, 1004, 1006, 1008, 1010, and 1011A are similar to blocks 602, 604, 606, 608, 610, and 611. If the UE detects that the first TAT expires, the flow proceeds to block 1012. At block 1012, the UE releases the SRS resource configuration instance configured with the first TA value and / or associated with the first TA value. If the UE detects that the second TAT expires, the flow proceeds to block 1014. At block 1014, the UE releases the SRS resource configuration instance configured with the second TA value and / or associated with the second TA value.

[0210] Fig. 10B Shows something like Fig. 10A Example method 1000B for scenario 1000A is shown, except that method 1000B includes blocks 1011B, 1013, and 1015.

[0211] At block 1011B, the UE detects whether the first TAT and the second TAT have expired. If the UE detects that the first TAT and the second TAT have expired, the process proceeds to block 1013. At block 1013, the UE performs the release actions described in blocks 1012 and / or 1014. If the UE does not detect that the first TAT and the second TAT have expired, the process proceeds to block 1015. At block 1015, the UE avoids performing the release actions described in blocks 1012 and / or 1014.

[0212] Next go to Fig.11A , an example method 1100A in which a UE (e.g., UE 102) implements operations for performing multiple TA values ​​in a multi-TRP scenario.

[0213] Method 1100A starts at block 1102. Blocks 1102, 1104, 1106, 1108, 1110, and 1111A are similar to blocks 602, 604, 606, 608, 610, and 611. If the UE detects that the first TAT expires, the flow proceeds to block 1112. At block 1112, the UE clears PUSCH resources configured with the first TA value and / or associated with the first TA value for semi-persistent CSI reporting. If the UE detects that the second TAT expires, the flow proceeds to block 1114. At block 1114, the UE clears PUSCH resources configured with the second TA value and / or associated with the second TA value for semi-persistent CSI reporting.

[0214] Fig. 11B Shows something like Fig.11A Example method 1100B for scenario 1100A is shown, except that method 1100B includes blocks 1111B, 1113, and 1115.

[0215] At block 1111B, the UE detects whether the first TAT and the second TAT have expired. If the UE detects that the first TAT and the second TAT have expired, the process proceeds to block 1113. At block 1113, the UE performs the clearing actions described in blocks 1112 and / or 1114. If the UE does not detect that the first TAT and the second TAT have expired, the process proceeds to block 1115. At block 1115, the UE avoids performing the clearing actions described in blocks 1112 and / or 1114.

[0216] Similar to method 600 , a more detailed description of elements of methods 800A- 1100B is generally described above.

[0217] In some cases, in response to expiration of the first TAT, the UE releases, clears or suspends the configured resources, or sends an RRC notification to release the configured resources in the first serving cell set, wherein the configured resources are associated with the first TA value or the first index. In some such cases, the first TAG is a STAG. In some such cases, the first TA value belongs to a STAG or is associated with a STAG. In some such cases, the first TAT is associated with a STAG.

[0218] In some cases, in response to the expiration of the second TAT, the UE releases, clears or suspends the configured resources, or sends an RRC notification to release the configured resources in the second serving cell set, wherein in some implementations, the configured resources are associated with the second TA value or the second index. In some such cases, the second TAG is a STAG. In some such cases, the second TA value belongs to a STAG or is associated with a STAG. In some such cases, the second TAT is associated with a STAG.

[0219] In some cases, the configured resources are one of: (i) PUCCH resources, (ii) SRS resources, (iii) configured downlink assignments (e.g., DL SPS), (iv) configured uplink grants, and / or (v) PUSCH resources, where the PUSCH resources are used for semi-persistent CSI reporting.

[0220] In some cases, if the configured resource is associated with a first TA value, the configured resource complies with at least one of the following: (i) the configured resource is sent via the first TA value, (ii) the configured resource or the configuration for the configured resource includes the first TA value, (iii) the configuration for the configured resource includes a first index, (iv) the configured resource is sent via spatial transmission filters / parameters derived from a spatial relationship (or UL / joint TCI state or reference signal) associated with or including the first TA value, and / or (v) the configured resource is received via spatial reception filters / parameters derived from a joint TCI state (or TCI state, QCL assumption or reference signal) associated with or including the first TA value.

[0221] In some cases, if the configured resource is associated with a second TA value, the configured resource complies with at least one of the following: (i) the configured resource is sent via the second TA value, (ii) the configured resource or the configuration for the configured resource includes the second TA value, (iii) the configuration for the configured resource includes a second index, (iv) the configured resource is sent via spatial transmission filters / parameters derived from a spatial relationship (or UL / joint TCI state or reference signal) associated with or including the second TA value, and / or (v) the configured resource is received via spatial reception filters / parameters derived from a joint TCI state (or TCI state, QCL assumption or reference signal) associated with or including the second TA value.

[0222] In some cases, the UE performs at least one of the following actions in response to expiration of the first TAT: (i) releasing, clearing, or suspending configured resources, or sending an RRC notification to release, clear, or suspend configured resources associated with the first TRP / TAG / TAT / TA value or the first index in all serving cells; and / or (ii) releasing, clearing, or suspending configured resources, or sending an RRC notification to release, clear, or suspend configured resources in all serving cells. In some such cases, the first TAG is a PTAG. In some such cases, the first TA value belongs to a PTAG or is associated with a PTAG. In some such cases, the first TAT is associated with a PTAG.

[0223] In some cases, the UE performs at least one of the following actions in response to the expiration of the second TAT: (i) releasing, clearing, or suspending configured resources, or sending an RRC notification to release, clear, or suspend configured resources associated with the second TRP / TAG / TAT / TA value or the second index in all serving cells; and / or (ii) releasing, clearing, or suspending configured resources, or sending an RRC notification to release, clear, or suspend configured resources in all serving cells. In some such cases, the second TAG is a PTAG. In some such cases, the second TA value belongs to a PTAG or is associated with a PTAG. In some such cases, the second TAT is associated with a PTAG.

[0224] In some cases, the UE maintains, retains, or otherwise stores the first TA value in response to expiration of the first TAT. In some such cases, the first TAG is a STAG. In some such cases, the first TA value belongs to or is associated with a STAG. In some such cases, the first TAT is associated with a STAG.

[0225] Alternatively, the UE performs at least one of the following actions in response to the expiration of the first TAT: (i) maintaining, retaining, or otherwise storing all indicated or derived TA values ​​associated with the first TRP / TAG / TAT / TA value or the first index on all TAGs; (ii) maintaining, retaining, or otherwise storing the second TA value; and / or (iii) maintaining, retaining, or otherwise storing all indicated or derived TA values ​​on all TAGs. In some such cases, the first TAG is a PTAG. In some such cases, the first TA value belongs to or is associated with a PTAG. In some such cases, the first TAT is associated with a PTAG.

[0226] In some cases, the UE maintains, retains or stores the second TA value in response to the expiration of the second TAT. In some such cases, the second TAG is a STAG. In some such cases, the second TA value belongs to or is associated with a STAG. In some such cases, the second TAT is associated with a STAG.

[0227] Alternatively, the UE performs at least one of the following actions in response to the expiration of the second TAT: (i) maintaining, retaining or storing all indicated or derived TA values ​​associated with the second TRP / TAG / TAT / TA value or the second index on all TAGs; (ii) maintaining, retaining or storing the first TA value; and / or (iii) maintaining, retaining or storing all indicated or derived TA values ​​on all TAGs. In some such cases, the second TAG may be a PTAG. In some such cases, the second TA value may belong to or be associated with a PTAG. In some such cases, the second TAT may be associated with a PTAG.

[0228] Next go to Fig. 12A , an example method 1200A in which a UE (e.g., UE 102) implements operations for performing multiple TA values ​​in a multi-TRP scenario.

[0229] Method 1200A starts at block 1202. Blocks 1202, 1204, 1206, 1208, 1210, and 1211 are similar to blocks 602, 604, 606, 608, 610, and 611. If the UE detects that the first TAT expires, the flow proceeds to block 1212A. At block 1212A, the UE triggers a CBRA procedure associated with the first TA value with the base station. If the UE detects that the second TAT expires, the flow proceeds to block 1214A. At block 1214A, the UE triggers a CBRA procedure associated with the second TA value with the base station.

[0230] Fig. 12B Shows something like Fig. 12A Example method 1200B for scenario 1200A is shown, except that method 1200B includes blocks 1212B and 1214B.

[0231] If the UE detects that the first TAT expires, the flow proceeds to block 1212B. At block 1212B, the UE sends a first MAC CE indicating the expiration of the first TA value to the base station. If the UE detects that the second TAT expires, the flow proceeds to block 1214B. At block 1214B, the UE sends a second MAC CE indicating the expiration of the second TA value to the base station.

[0232] In some implementations, the first MAC CE and the second MAC CE have the same MAC CE format. In some implementations, the UE sends a MAC PDU including a subheader of the first MAC CE and the first MAC CE to the base station at block 1212B. In some implementations, the UE sends a MAC PDU including a subheader of the second MAC CE and the second MAC CE to the base station at block 1214B.

[0233] In some implementations, the UE includes in the first MAC CE an ID of the first TA value or an ID of the first TAG associated with the first TA value. In some implementations, the UE includes in the second MAC CE an ID of the second TA value or an ID of the second TAG associated with the second TA value.

[0234] Fig. 12C Shows something like Fig. 12A Example method 1200C for scenario 1200A is shown, except that method 1200C includes blocks 1212C and 1214C.

[0235] If the UE detects that the first TAT has expired, the flow proceeds to block 1212C. At block 1212C, the UE sends a first RRC message to the base station indicating the expiration of the first TA value. If the UE detects that the second TAT has expired, the flow proceeds to block 1214C. At block 1214C, the UE sends a second RRC message to the base station indicating the expiration of the second TA value.

[0236] In some implementations, the first RRC message and the second RRC message have the same RRC message format. For example, the first RRC message and the second RRC message are UE assistance information messages (eg, UEAssistanceInformation messages).

[0237] In some implementations, the UE includes in the first RRC message an ID of the first TA value or an ID of the first TAG associated with the first TA value. In some implementations, the UE includes in the second RRC message an ID of the second TA value or an ID of the second TAG associated with the second TA value.

[0238] Fig.12D Shows something like Fig. 12A Example method 1200D for scenario 1200A is shown, except that method 1200D includes blocks 1212D and 1214D.

[0239] If the UE detects that the first TAT has expired, the flow proceeds to block 1212D. At block 1212D, the UE sends a first PUCCH transmission to the base station indicating the expiration of the first TA value. If the UE detects that the second TAT has expired, the flow proceeds to block 1214D. At block 1214D, the UE sends a second PUCCH transmission to the base station indicating the expiration of the second TA value.

[0240] In some implementations, the UE includes in a first PUCCH transmission an ID of a first TA value or an ID of a first TAG associated with the first TA value. In some implementations, the UE includes in a second PUCCH transmission an ID of a second TA value or an ID of a second TAG associated with the second TA value.

[0241] Fig.12E Shows something like Fig. 12A Example method 1200E for scenario 1200A is shown, except that method 1200E includes blocks 1211E and 1216 .

[0242] At block 1211E, the UE detects whether the first TAT has expired, whether the second TAT has expired, and whether both the first TAT and the second TAT have expired. If the UE detects that the first TAT has expired, the UE performs the actions described in blocks 1212B, 1212C, or 1212D. If the UE detects that the second TAT has expired, the UE performs the actions described in blocks 1214B, 1214C, or 1214D. If the UE detects that both the first TAT and the second TAT have expired, the flow proceeds to block 1216. At block 1216, the UE triggers a CBRA procedure with the base station.

[0243] Similar to method 600 , a more detailed description of elements of methods 1200A- 1200E are generally detailed above.

[0244] In some cases, the UE performs an action when at least one of the following is satisfied or achieved: (i) the first TAT expires; (ii) the UE has UL data or UL channel / RS associated with the first index; (iii) the UE has UL data or UL channel / RS intended to be sent for the first TRP or associated with the first TRP; and / or (iv) the UE has UL data or UL channel / RS to be sent via the first TA value. In some such implementations, the action then performed by the UE is at least one of the following actions: (i) triggering or performing a contention-based or contention-free RA procedure associated with the first index; (ii) triggering or performing a contention-based or contention-free RA procedure intended for the first TRP, the first TAG, the first TAT, or the first TA value; and / or (iii) sending a first MAC-CE to the NW, wherein the second TAT has not expired.

[0245] In some cases, the UE performs an action when at least one of the following is satisfied or achieved: (i) the second TAT expires; (ii) the UE has UL data or UL channel / RS associated with a second index; (iii) the UE has UL data or UL channel / RS intended to be sent for a second TRP or associated with a second TRP; and / or (iv) the UE has UL data or UL channel / RS to be sent via a second TA value. In some such implementations, the action then performed by the UE is at least one of the following actions: (i) triggering or performing a contention-based or contention-free RA procedure associated with the second index; (ii) triggering or performing a contention-based or contention-free RA procedure intended for a second TRP, a second TAG, a second TAT, or a second TA value; and / or (iii) sending a second MAC-CE to the NW, wherein the first TAT has not expired.

[0246] In some cases, when a RA process is associated with or intended for at least one of (a) a first index and / or (b) a first TRP / TAG / TA value / TAT, at least one of the following is true: (i) MSG 0 or a PDCCH command for the RA process (e.g., received by the UE from the base station) indicates or is associated with the first index, wherein in some implementations, the RA process is a contention-free RA process; (ii) MSG 1 or MSG A for the RA process (e.g., sent by the UE to the base station) indicates or is associated with the first index; (iii) MSG 2 or MSG B for the RA process (e.g., received by the UE from the base station) indicates or is associated with the first index; and / or (iv) MSG 3 for the RA process (e.g., sent by the UE to the base station) or MSG 4 (e.g., received by the UE from the base station) indicates or is associated with the first index.

[0247] In some cases, when a RA process is associated with or intended for at least one of (a) a second index and / or (b) a second TRP / TAG / TA value / TAT, at least one of the following is true: (i) MSG 0 or a PDCCH command for the RA process (e.g., received by the UE from the base station) indicates the second index or is associated with the second index, wherein in some implementations, the RA process is a contention-free RA process; (ii) MSG 1 or MSG A for the RA process (e.g., sent by the UE to the base station) indicates the second index or is associated with the second index; (iii) MSG 2 or MSG B for the RA process (e.g., received by the UE from the base station) indicates the second index or is associated with the second index; and / or (iv) MSG 3 for the RA process (e.g., sent by the UE to the base station) or MSG 4 (e.g., received by the UE from the base station) indicates the second index or is associated with the second index.

[0248] In some implementations, the first MAC-CE and / or the second MAC-CE indicates at least one of: (i) a first index or a second index, (ii) which TA value or TAG expires; and / or (iii) an estimated TA offset or difference.

[0249] In some cases, when the base station receives the first MAC-CE, the base station sends a MSG 0 or a PDCCH command to the UE. In another implementation, when the NW receives the first MAC-CE, the NW sends a MSG 0 or a PDCCH command to the UE, wherein: (i) the MSG 0 or the PDCCH command indicates the first index or is associated with the first index, and / or (ii) if the first MAC-CE indicates the first index, the MSG 0 or the PDCCH command indicates the first index or is associated with the first index.

[0250] In some cases, when the base station receives the second MAC-CE, the base station sends a MSG 0 or a PDCCH command to the UE. In another implementation, when the NW receives the first MAC-CE, the NW sends a MSG 0 or a PDCCH command to the UE, wherein: (i) the MSG 0 or the PDCCH command indicates the second index or is associated with the second index, and / or (ii) if the first MAC-CE indicates the first index, the MSG 0 or the PDCCH command indicates the second index or is associated with the second index.

[0251] In some implementations, the first MAC-CE and / or the second MAC-CE refers to a TA expiration indication MAC-CE or a TA expiration report MAC-CE or is replaced by a TA expiration indication MAC-CE or a TA expiration report MAC-CE. In some implementations, the first MAC-CE and the second MAC-CE are the same MAC-CE. Alternatively, the first MAC-CE and the second MAC-CE are different MAC-CEs.

[0252] Next go to Fig.13 , an example method 1300 for a UE (e.g., UE 102) to implement operations for performing multiple TA values ​​in a multi-TRP scenario.

[0253] Method 1300 begins at block 1302. Blocks 1302, 1304, and 1306 are similar to blocks 602, 604, and 606. At block 1308, the UE starts or restarts a single TAT to maintain first UL synchronization and second UL synchronization with the base station. In some implementations, the single TAT is the third TAT mentioned above. At block 1310, the UE detects or determines whether the single TAT expires. At block 1312, in response to the expiration of the single TAT, the UE performs the actions described in 612 / 614, 712B, 812 / 814, 912 / 914, 1012 / 1014, 1112 / 1114, 1212A / 1214A, 1212B / 1214B, 1212C / 1212C, 1212D / 1214D, and / or 1216.

[0254] In some implementations, when the first TA value, the second TA value, or both the first TA value and the second TA value are received (e.g., upon receipt, in response to receipt, or after receipt), the UE starts or restarts a single TAT to maintain first UL synchronization and second UL synchronization with the UE.

[0255] Similar to method 600, a more detailed description of the elements of method 1300 is generally detailed above.

[0256] In some cases (including method 1300), the UE maintains a TAT (e.g., a third TAT) for the first TA value and the second TA value. In some implementations, the UE maintains a TAT (e.g., a third TAT) for the first TA value and the second TA value, wherein the third TAT is used to determine whether the first TA value and / or the second TA value has expired.

[0257] In some cases, the UE receives a third MAC-CE, wherein the third MAC-CE indicates or updates the first TA value and the second TA value at the same time. In some implementations, when the UE receives the third MAC-CE, the UE expects the third MAC-CE to indicate or update the first TA value and the second TA value at the same time. In some implementations, when the UE maintains a TAT (e.g., a third TAT) for the first TA value and the second TA value, the UE expects the third MAC-CE (if received) to indicate or update the first TA value and the second TA value at the same time.

[0258] In some implementations, if the UE receives the third MAC-CE, and if the third MAC-CE does not simultaneously indicate or update the first TA value and the second TA value, the UE ignores, discards, or otherwise does not use the third MAC-CE. In some implementations, when the UE maintains a TAT (e.g., a third TAT) for the first TA value and the second TA value, if the UE receives the third MAC-CE, and if the third MAC-CE does not simultaneously indicate or update the first TA value and the second TA value, the UE ignores, discards, or otherwise does not use the third MAC-CE.

[0259] In some cases, the base station maintains a TAT (e.g., a third TAT) for the first TA value and the second TA value. In some implementations, the base station maintains a TAT (e.g., a third TAT) for the first TA value and the second TA value, wherein the third TAT is used to determine whether the first TA value and / or the second TA value has expired.

[0260] In some cases, the base station sends a third MAC-CE, wherein the third MAC-CE indicates or updates the first TA value and the second TA value at the same time. In some implementations, when the base station sends the third MAC-CE, the base station may be required to indicate or update the first TA value and the second TA value at the same time. In some such implementations, the base station is not allowed to use the third MAC-CE to indicate or update only one of the first TA value or the second TA value. In some implementations, when the base station maintains a TAT (e.g., a third TAT) for the first TA value and the second TA value, the base station may be required to indicate or update the first TA value and the second TA value at the same time. In some implementations, when the base station maintains a TAT (e.g., a third TAT) for the first TA value and the second TA value, and if the base station sends the third MAC-CE, the base station may be required to indicate or update the first TA value and the second TA value in the third MAC-CE.

[0261] In some implementations, when the UE maintains one TAT (e.g., a third TAT) for the first TA value and the second TA value, the first TA value and the second TA value belong to a certain TAG (e.g., the third TAG) or are associated with a certain TAG. In some implementations, when the UE maintains one TAT (e.g., the third TAT) for the first TA value and the second TA value, the first TA value and the second TA value belong to different TAGs (e.g., the first TAG and the second TAG) or are associated with different TAGs, respectively.

[0262] In some implementations, the third MAC-CE is one of: (i) an (enhanced) timing advance command MACCe, (ii) an (enhanced) timing advance command in a RAR response or in a MAC payload for a RAR response, or (iii) an (enhanced) absolute timing advance command in response to an MSGA transmission including a C-RNTI MAC CE.

[0263] In some implementations, when the UE is configured to maintain two TATs (e.g., a first TAT and a second TAT) in at least one serving cell and / or maintain the two TATs, a third MAC-CE is also used. In some implementations, the third MAC-CE is used to indicate or update the first TA value and / or the second TA value, wherein: (i) in some implementations, the first TA value and the second TA value are indicated or updated simultaneously; (ii) in some implementations, the first TA value and the second TA value are indicated or updated separately (e.g., at different time points); and / or (iii) the first TA value and the second TA value belong to different TATs (e.g., the first TAT and the second TAT) or are associated with different TATs.

[0264] Next go to Fig.14 , an example method 1400 for a UE (e.g., UE 102) to implement operations for performing multiple TA values ​​in a multi-TRP scenario.

[0265] Method 1400 begins at block 1402. Blocks 1402 and 1404 are similar to blocks 602 and 604. At block 1406, the UE receives a first TA value from a base station. At block 1408, the UE uses the first TA value to send an UL transmission to the base station. At block 1410, upon receiving the first TA value, the UE starts or restarts a first TAT to maintain first UL synchronization with the base station. At block 1412, the UE receives a MAC CE including an incremental value from the base station. At block 1414, the UE derives a second TA value by using the first TA value and the incremental value. At block 1416, in some implementations, upon receiving the incremental value or deriving the second TA value, the UE starts or restarts a second TAT to maintain second UL synchronization with the base station. At block 1418, the UE uses the second TA value to send an UL transmission to the base station. At block 1420, when the first TAT expires, the UE deems or determines that the second TAT expires.

[0266] Similar to method 600, a more detailed description of the elements of method 1400 is generally detailed above.

[0267] In some cases, the UE derives the second TA value. In some implementations, the exact value of the second TA value is not explicitly indicated or signaled by the base station to the UE (e.g., MAC-CE or DCI). In some implementations, the exact value of the first TA value is explicitly indicated or signaled by the base station (e.g., MAC-CE or DCI).

[0268] In some implementations, if the UE derives the second TA value, there is no TAT for or associated with the second TA value (e.g., a dedicated TAT). In some implementations, if the UE derives the second TA value, there is no TAG to include or associated with the second TA value (e.g., a dedicated TAG).

[0269] In some cases, the UE receives the incremental value. In some implementations, the second TA value is derived by using the incremental value. In some implementations, the second TA value is derived by using the first TA value and the incremental value. In some implementations, the second TA value is the first TA value plus the incremental value. In some implementations, the possible value range of the incremental value plus the first TA value is the same as the possible value range of the first TA value or is a subset of the possible value range of the first TA value. In some implementations, the NW indicates or signals the incremental value. In some such implementations, the NW indicates or signals the incremental value via one of RRC, MAC-CE, or DCI.

[0270] In some implementations, the increment value is indicated or updated by a fourth MAC-CE. In some implementations, the fourth MAC-CE is the MAC-CE described in method 1400. In some implementations, the fourth MAC-CE can indicate or update the first TA value. In some implementations or alternatively, the fourth MAC-CE cannot indicate or update the first TA value.

[0271] In some implementations, if the UE receives a fourth MAC-CE and the fourth MAC-CE does not indicate or update the increment value, the currently applied increment value is kept used or is not changed. In some implementations, if (i) the fourth MAC-CE is capable of indicating or updating the increment value and the first TA value, and (ii) the UE receives a fourth MAC-CE that does not indicate or update the increment value, the currently applied increment value is used.

[0272] In some implementations, the fourth MAC-CE includes a bit or field to indicate whether the increment value is indicated or updated by the fourth MAC-CE. In some implementations, the fourth MAC-CE includes a bit or field to indicate whether the increment value is present in the fourth MAC-CE or included in the fourth MAC-CE.

[0273] In some implementations, if the first TAT expires, the UE determines that the second TA value expires or is outdated. In some implementations, if the first TAT expires, the UE determines that the incremental value expires or is outdated. In other implementations, the base station configures or indicates to the UE a special timer to determine whether the incremental value is expired / outdated or valid. In some implementations, the UE maintains a special timer to determine whether the incremental value is expired / outdated or valid. In some implementations, if the special timer expires, the UE may determine that the second TA value expires or is outdated.

[0274] Note that throughout this disclosure, “TA value expires” may mean at least one of: (i) the TA value is not synchronized, (ii) the TA value is outdated, and / or (iii) the TA value is uplink time aligned.

[0275] Note that throughout this disclosure, a neighboring cell may refer to or be replaced by at least one of the following: (i) a non-serving cell, (ii) a cell having a PCI different from the PCI of the serving cell, and / or (iii) a TRP associated with a PCI different from the PCI of the same serving cell.

[0276] Note that throughout this disclosure, a joint TCI state may refer to or be replaced by at least one of: (i) a beam applicable to both DL and UL transmissions (e.g., DL or UL channels, DL or UL RS, etc.), (ii) a spatial filter for transmission and / or reception, (iii) a spatial parameter for transmission and / or reception, (iv) a spatial relationship for transmission and / or reception, and / or (v) a spatial assumption for transmission and / or reception.

[0277] Note that throughout this disclosure, the joint TCI state may refer to or be replaced by a common TCI state or a unified TCI state.

[0278] Note that throughout this document, UL TCI state may refer to or be replaced by at least one of: (i) UL beam, (ii) spatial relationship, (iii) spatial transmit filter, (iv) transmit precoder, (v) spatial parameters, and / or (vi) spatial relationship.

[0279] Note that throughout this disclosure, the DL TCI state may be referred to as or replaced by at least one of the following: (i) TCI applicable to a DL channel or RS, (ii) TCI associated with quasi co-location (QCL) type D, (iii) QCL assumption, (iv) DL beam, (v) spatial receive filter, (vi) spatial parameters, (vii) spatial relationship, and / or (viii) spatial assumption.

[0280] Note that throughout this disclosure, a TCI pool (e.g., a joint TCI pool, a UL TCI pool, a DL TCI pool) may be referred to as or represent a (RRC) configuration or list that may include or contain one or more TCIs (indexes). Note that throughout this disclosure, "TCI" may be referred to as or replaced by "TCI state". Note that throughout this disclosure, "TCI pool" may be referred to as or replaced by "TCI state pool".

[0281] It should be noted that throughout this disclosure, a UE may have one or more of the following attributes or behaviors. The following attributes or behaviors of a UE may also imply associated attributes or behaviors of a base station: (i) The UE is configured with a base station in a serving cell and / or is served by the base station. (ii) The UE is configured to communicate with a base station in the serving cell. (iii) The UE is configured with one or more serving cells by the base station, and the one or more serving cells may include the serving cell. (iv) The UE is activated or instructed by the base station to activate one or more serving cells, and the one or more serving cells may include the serving cell. (v) The UE has been configured and / or instructed by the base station to have one or more BWPs. The UE has been instructed and / or configured by the base station to have a BWP in the serving cell. (a) In some implementations, the BWP is activated as an active BWP; (b) In some implementations, the BWP refers to an active BWP; (c) In some implementations, the BWP is an active DL BWP; (d) In some implementations, the BWP is an active ULBWP; (e) In some implementations, the BWP is an initial BWP; (f) In some implementations, the BWP is a default BWP; (g) In some implementations, the BWP is a dormant BWP. (vi) The UE is in one of the RRC_CONNECTED state, the RRC_INACTIVE state, or the RRC_IDLE state.

[0282] It should be noted that throughout this disclosure, the expression “X / Y” may include the meaning of “X or Y”. It should be noted that throughout this disclosure, the expression “X / Y” may include the meaning of “X and Y”. It should be noted that throughout this disclosure, the expression “X / Y” may include the meaning of “X and / or Y”. It should be noted that throughout this disclosure, the expression “(A)B” or “B(A)” may include the concept of “only B”. It should be noted that throughout this disclosure, the expression “(A)B” or “B(A)” may include the concept of “A+B” or “B+A”.

[0283] Note that throughout this disclosure, a panel may refer to an antenna (port) group or an antenna (port) set. There may be more than one DL / UL beam associated with one panel. When a transmitting node (UE or base station) is performing a transmission via a panel, only one beam associated with the panel may be used to perform the transmission. For a transmitter comprising more than one panel (e.g., two panels), it may happen that two beams associated with two panels, respectively, are used to perform the transmission.

[0284] Note that throughout this disclosure, a TRP identifier may mean or be referred to as a (candidate) value of a TRP identifier. A first TRP identifier may be a first candidate value of a TRP identifier or a first TRP identifier value. A second TRP identifier may be a second candidate value of a TRP identifier or a second TRP identifier value.

[0285] It should be noted that throughout this disclosure, a panel identifier may mean or be referred to as a (candidate) value of a panel identifier. A first panel identifier may be a first candidate value of a panel identifier or a first panel identifier value. A second panel identifier may be a second candidate value of a panel identifier or a second panel identifier value.

[0286] Note that throughout this disclosure, a TCI field may mean or be referred to as a field used or applied to or reused to indicate one or more TCI states.

[0287] Note that throughout this disclosure, "joint mode" or "joint TCI state mode" may mean at least one of the following: (i) a TCI field in a DCI format or an indicated TCI state referenced / mapped to one of the joint TCI state pools, the DL TCI state pool, or the UL TCI state pool; and / or (ii) a beam indication or an indicated TCI state is applied to both sending UL transmissions and / or receiving DL transmissions.

[0288] Note that throughout this disclosure, "separate mode" or "separate TCI state mode" may mean at least one of the following: (i) the TCI field in DCI format or the indicated TCI state referenced / mapped to one of the joint TCI state pool, DL TCI state pool or UL TCI state pool; and / or (ii) the beam indication or the indicated TCI state applies to (only) sending UL transmissions or (only) receiving DL transmissions.

[0289] Note that throughout this disclosure, "UL mode" or "UL TCI state mode only" may mean at least one of the following: (i) TCI field in DCI format or indicated TCI state referenced / mapped to UL TCI state pool (joint TCI state pool); and / or (ii) beam indication or indicated TCI state applied to (only) sending UL transmissions.

[0290] Note that throughout this disclosure, "DL mode" or "DL-only TCI state mode" may mean at least one of the following: (i) TCI field in DCI format or indicated TCI state referenced / mapped to a DL TCI state pool (joint TCI state pool); and / or (ii) beam indication or indicated TCI state applied to (only) received DL transmissions.

[0291] It is noted that throughout this disclosure, when a process or description is related to a serving cell, it may mean that the process or description is related to an active (DL / UL) BWP in the serving cell.

[0292] Note that throughout this disclosure, “TA timer” or “TAT” may be referred to as or replaced with “TA alignment timer”.

[0293] It should be noted that some or all of the foregoing or following embodiments may be combined or formed jointly into a new or another embodiment.

[0294] It should be noted that the aforementioned or following embodiments can be used to solve at least (but not limited to) the problems or scenarios mentioned in the present disclosure.

[0295] The following additional considerations may apply to the foregoing and following discussions.

[0296] It should be noted that any two or more of the preceding or following paragraphs, (sub)bullet points, key points, actions or claims described in each method / embodiment / implementation may be logically, reasonably and appropriately combined to form a specific method.

[0297] It should be noted that any sentence, paragraph, (sub) bullet point, key point, action or claim described in each of the above or following methods / embodiments / implementations can be implemented independently and separately to form a specific method. The dependencies in the following methods / embodiments / implementations, such as "based on", "more specifically", "wherein", etc., are only possible embodiments that do not limit the specific method.

[0298] Note that some or all of the following terms and assumptions may be used hereinafter: (i) Base Station (BS): A network central unit or network node in NR that controls one or more TRPs associated with one or more cells. Communication between the base station and the TRP is via fronthaul. The base station may be referred to as a central unit (CU), eNB, gNB, or NodeB. (ii) Transmission and Reception Point (TRP): A transmission and reception point provides network coverage and communicates directly with the UE. The TRP may be referred to as a distributed unit (DU) or a network node. (iii) Cell: A cell consists of one or more associated TRPs (i.e., the coverage of a cell consists of the coverage of all associated TRPs). One cell is controlled by one base station. A cell may be referred to as a TRP group (TRPG). (iv) Serving Beam: A serving beam for a UE is a beam generated by a network node (e.g., a TRP) configured to communicate with the UE (e.g., for transmission and / or reception). (v) Candidate Beam: A candidate beam for a UE is a candidate for a serving beam. A serving beam may or may not be a candidate beam.

[0299] The user device (e.g., UE 102) in which the technology of the present disclosure can be implemented can be any suitable device capable of wireless communication, such as a smart phone, a tablet computer, a laptop computer, a mobile game 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 smart watch), a wireless hotspot, a femtocell or a broadband router. In addition, in some cases, the user device can be embedded in an electronic system (such as a head unit of a vehicle or an advanced driver assistance system (ADAS)). Further, the user device can be operated as an Internet of Things (IoT) device or a mobile Internet device (MID). Depending on the type, 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.

[0300] Certain embodiments are described in the present disclosure as including logic or multiple components or modules. A module may be a software module (e.g., code stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit that is capable of performing certain operations and may be configured or arranged in a certain manner. A hardware module may include a dedicated circuit system or logic that is permanently configured (e.g., as a dedicated processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC)) to perform certain operations. A hardware module may also include programmable logic or circuit systems that are temporarily configured by software to perform certain operations (e.g., as contained within a general-purpose processor or other programmable processor). The decision to implement a hardware module in a dedicated and permanently configured circuit system or in a temporarily configured circuit system (e.g., configured by software) may be driven by cost and time considerations.

[0301] When implemented in software, the techniques may be provided as part of an operating system, a library used by multiple applications, a specific software application, etc. The software may be executed by one or more general-purpose processors or one or more special-purpose processors.

Claims

1. A method for managing synchronization, the method being implemented in a user equipment (UE) and comprising: receiving a configuration including a first timing advance (TA) value and a second TA value from a radio access network (RAN); operating a first TA timer (TAT) corresponding to the first TA value to manage synchronization of a first uplink (UL) transmission with a first receiver in the RAN; operating a second TAT corresponding to the second TA value to manage synchronization of a second UL transmission with a second receiver in the RAN; stopping the first UL transmission in response to expiration of the first TAT; and The second UL transmission is stopped in response to expiration of the second TAT.

2. The method of claim 1, wherein: The first receiver is a first transmit and receive point (TRP) of a node in the RAN; and The second receiver is a second TRP of the node; The UE is configured to communicate with the first TRP and the second TRP in a multi-TRP (M-TRP) mode.

3. The method of claim 2, further comprising: After the first TAT expires and before the second TAT expires, continue the second UL transmission to the second TRP.

4. The method of claim 3, further comprising: The continuing of the second UL transmission includes continuing to receive scheduling for the second UL transmission from the RAN.

5. The method according to any one of claims 2 to 4, wherein: The first TRP is associated with a first TA group (TAG), and The second TRP is associated with a second TAG.

6. The method of claim 5, wherein: The first TA value is associated with a first TCI state, and The second TA value is associated with a second TCI state.

7. The method of claim 1, wherein: The first receiver operates in a serving cell; and The second receiver operates in a non-serving cell.

8. A method as claimed in any one of the preceding claims, wherein: Operating the first TAT includes starting or restarting the first TAT in response to receiving the first TA value; and Operating the second TAT includes starting or restarting the second TAT in response to receiving the second TA value.

9. The method according to any one of the preceding claims, further comprising: An indication is received from the RAN to enable use of multiple TA values ​​in the serving cell.

10. The method of any preceding claim, wherein receiving the first TA value comprises: sending a random access preamble to the first receiver; as well as The first TA value is received from the first receiver in response to the random access preamble.

11. The method of any one of claims 1 to 9, wherein receiving the first TA value comprises: A medium access control (MAC) control element (CE) is received including the first TA value.

12. The method of any one of the preceding claims, wherein receiving the first TA value comprises: A MAC protocol data unit (PDU) including the first TA value is received.

13. The method of any one of the preceding claims, further comprising: In response to the first TAT expiring, sending a first expiration indication of the first TAT expiring to the RAN; as well as In response to the second TAT expiring, sending a second expiration indication of the expiration of the second TAT to the RAN.

14. The method of claim 13, wherein each of the first expiration indication and the second expiration indication is included in a corresponding MAC CE.

15. A user equipment (UE), comprising: Transceiver; as well as Processing hardware configured to implement a method according to any one of the preceding claims.

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