Managing multiple timing advance values for multiple transmission and / or reception points

Abstract

To manage synchronization, a radio access network (RAN) node transmits to a user equipment (UE) a first timing advance (TA) value for managing synchronization of a first transmission between the UE and a first transmit and receive point (TRP) of the RAN node (606); sending a second TA value to the UE for managing synchronization of a second transmission between the UE and a second TRP of the RAN node (608); stopping scheduling the first transmission in response to determining that synchronization of the first transmission is invalid (612); and stopping scheduling the second transmission in response to determining that the synchronization of the second transmission is invalid (614).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority and filing date of U.S. Provisional Patent Application No. 63 / 393,818, filed on July 29, 2022, entitled “MAINTAINING A TA 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 ADVANCEVALUES FOR MULTIPLE TRANSMIT AND / OR RECEIVE POINTS”. The entire contents of the provisional applications are hereby expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to wireless communications, and more particularly to managing multiple timing advance values ​​for communications between a user equipment (UE) and a base station through multiple transmit and / or receive points (TRPs). 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 otherwise may not be considered prior art at the time of filing, are neither explicitly nor implicitly admitted to be prior art to the present disclosure.

[0005] Typically, 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] Currently, there are technologies for supporting multi-TRP (mTRP) operation for physical downlink shared channel (PDSCH), physical downlink control channel (PDCCH), physical uplink shared channel (PUSCH) and physical uplink control channel (PUCCH) transmissions. In particular, a maximum of two TRPs are currently supported in mTRP operation.

[0007] In addition, two different mechanisms are currently used to support mTRP PDSCH transmission: single downlink control information (DCI) and multiple DCI (multi-DCI). Further, mTRP PDSCH transmission is extended to inter-cell operation. In inter-cell operation, the gNB can configure a synchronization signal block (SSB) associated with a physical cell identity (PCI) that is different from the serving cell's physical cell identity (PCI) (referred to as an additional PCI) for the UE. The gNB can configure up to seven different additional PCIs to the UE, and only one of the additional PCIs is activated for inter-cell mTRP operation. The additional PCI can be associated with one or more transmission configuration indication (TCI) states, and the gNB can dynamically schedule PDSCH transmission from any TRP by indicating the TCI in the DCI and / or indicating a specific TCI state. In addition, mTRP PDCCH transmission, PUSCH transmission, and PUCCH transmission are supported for both intra-cell operation and inter-cell operation.

[0008] In mTRP operation, the gNB ensures that transmissions from / to two TRPs connected to the gNB are synchronized for UEs in different locations within the coverage of the two TRPs. In some deployment scenarios (e.g., the two TRPs belong to different cells or the distance between the two TRPs is large), the gNB cannot ensure that transmissions from / to the two TRPs are always synchronized for UEs in different locations within the coverage of the two TRPs. Therefore, to achieve mTRP operation, the UE and the gNB maintain two uplink synchronizations for the communication between the UE and the two TRPs. However, it is unclear how the gNB manages the scenario in which one of the two uplink synchronizations is no longer valid. Summary of the invention

[0009] An example embodiment of these techniques is a method for managing synchronization, which is implemented in a radio access network (RAN) node and includes: sending a first timing advance (TA) value to a user equipment (UE) for managing synchronization of a first transmission between the UE and a first transmit and receive point (TRP) of the RAN node; sending a second TA value to the UE for managing synchronization of a second transmission between the UE and a second TRP of the RAN node; stopping scheduling the first transmission in response to determining that synchronization of the first transmission is invalid; and stopping scheduling the second transmission in response to determining that synchronization of the second transmission is invalid.

[0010] Another example embodiment of the techniques is a radio access network (RAN) comprising a transceiver; and processing hardware configured to implement the method of any one of the preceding claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1A is a block diagram of an example wireless communication system in which a radio access network (RAN) and / or user equipment (UE) may implement the techniques of the present disclosure;

[0012] Figure 1B Yes, you can Figure 1A A block diagram of an example base station operating in a RAN of FIG. 1 , the base station comprising a central unit (CU) and a distributed unit (DU);

[0013] Figure 2A is a block diagram of an example protocol stack, according to which, Figure 1A The UE can be connected with Figure 1A Communicate with the RAN;

[0014] Figure 2B is a block diagram of an example protocol stack, according to which, Figure 1A The UE can be connected with Figure 1A or Figure 1B The DU and CU of the base station communicate;

[0015] Figure 3A Yes Figure 2A and / or Figure 2B A block diagram of the detailed structure of the various sub-layers of the depicted protocol stack, including scheduling and / or priority handling functionality;

[0016] 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;

[0017] Figure 4A is a block diagram of a HARQ entity including multiple HARQ processes and communicating using transport channels to multiple TRPs;

[0018] 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;

[0019] Figure 4C is with Figure 4A A block diagram of a HARQ entity similar to that of a HARQ entity, but wherein the HARQ entity communicates with a single TRP;

[0020] 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 for performing communications with a base station;

[0021] Figure 5B is with Figure 5AMessaging diagram for an example scenario similar but where the UE receives UL and DL configuration parameters in separate radio resource configuration messages;

[0022] Figure 5C is with Figure 5A A message passing diagram for an example scenario similar to this but in which the base station sends the UL configuration parameters to the UE via the second TRP instead of the first TRP;

[0023] Figure 5D is with Figure 5A A message passing diagram for an example scenario similar to that in which the UE receives a response from the base station when performing a random access procedure via a first TRP instead of via a second TRP;

[0024] Figure 5E is with Figure 5A Message passing diagram for a similar example scenario but where the UE receives a PDCCH order (PDCCHorder) via a first TRP instead of a second TRP;

[0025] Figure 6 Among them Figure 1A and / or Figure 1B A flowchart of an example method for a RAN node to determine whether to stop scheduling a UE to send UL transmission to a first TRP or to stop scheduling a UE to send UL transmission to a second TRP based on whether a first UL synchronization is invalid or a second UL synchronization is invalid;

[0026] Fig. 7A is similar to Figure 6 A flowchart of an example method of determining whether to flush a HARQ buffer for a first set of HARQ processes for a first TRP or to flush a HARQ buffer for a second set of HARQ processes for a second TRP;

[0027] Figure 7B is with Fig. 7A A flowchart of an example method similar to that described above but wherein determining whether to flush HARQ buffers for processes for first and second TRPs is based on whether first and second UL synchronization is invalid;

[0028] Fig. 8A is with Figure 6 A flowchart of an example method similar to the above but wherein determining whether to clear the configured authorization associated with the first TRP or clear the configured authorization associated with the second TRP;

[0029] Figure 8B is with Fig. 8A A flowchart of an example method similar to the above but wherein determining whether to clear configured grants associated with first and second TRPs is based on whether first and second UL synchronization is invalid;

[0030] Fig. 9A is with Figure 6 A flowchart of an example method similar to the above but wherein determining whether to release PUCCH CSI resources and / or scheduling request resource configuration instances associated with a first TRP or to release PUCCH CSI resources and / or scheduling request resource configuration instances associated with a second TRP;

[0031] Fig. 9B is with Fig. 9A a flowchart of an example method similar to that of the present invention but wherein determining whether to release PUCCH CSI resources and / or scheduling request resource configuration instances associated with first and second TRPs is based on whether first and second UL synchronization is invalid;

[0032] Fig. 10A is with Figure 6 a flowchart of an example method similar to the above but wherein determining whether to release an SRS resource configuration instance associated with a first TRP or to release an SRS resource configuration instance associated with a second TRP;

[0033] Fig. 10B is with Fig. 10A a flowchart of an example method similar to that described above but in which determining whether to release SRS resource configuration instances associated with first and second TRPs is based on whether first and second UL synchronization is invalid;

[0034] Fig.11A is with Figure 6 A flowchart of an example method similar to the above but wherein determining whether to clear PUSCH resources for CSI reporting associated with a first TRP or to clear PUSCH resources for CSI reporting associated with a second TRP;

[0035] Fig. 11B is with Fig.11A a flowchart of an example method similar to that described above but wherein determining whether to clear PUSCH resources associated with first and second TRPs for CSI reporting is based on whether first and second UL synchronization is invalid;

[0036] Fig.12 is with Figure 6 A flowchart of an example method similar to the above but wherein determining whether to send a random access trigger command for a first TRP or to send a random access trigger command for a second TRP;

[0037] Fig.13 Among them Figure 1A and / or Figure 1B A flowchart of an example method for a RAN node to determine whether a first UL synchronization is invalid or a second UL synchronization is invalid based on whether a first TAT is expired or a second TAT is expired;

[0038] Fig.14 is with Fig.13 A flowchart of an example method similar to the above but wherein the determination is made based on whether the indication indicates a first UL synchronization invalidity or an indication of a second UL synchronization invalidity; and

[0039] Fig.15 Among them Figure 1A and / or Figure 1B Flowchart of an example method in which a RAN node sends first and second TA values ​​for first and second UL synchronization and then maintains first and second UL synchronization with a UE. DETAILED DESCRIPTION

[0040] 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.

[0041] Base station 104 may cover one or more cells (e.g., cells 124 and 125) having one or more transmit and / or receive 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 using TRPs 107-1 and 107-2 and operates cell 125 using TRP 107-3, and base station 106 operates cell 126 using TRPs 108-1 and 108-2. Cells 124 and 125 operate at the same one or more carrier frequencies. Cell 126 may operate at the same one or more carrier frequencies as cells 124 and 125. Alternatively, cell 126 may operate at 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 an (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 an (ng-)eNB, cell 126 is an EUTRA cell. Cells 124, 125, and 126 may be 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 "NR" for short) or E-UTRA air interface to communicate with base station 104 via TRP 107-1, TRP 107-2, 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 for interconnecting NG RAN nodes (e.g., X2 or Xn interface).

[0042] 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 for 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.

[0043] 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 traffic, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The PGW 116 provides a connection 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 traffic, etc., AMF 164 is configured to manage authentication, registration, paging and other related functions, and SMF 166 is configured to manage PDU sessions.

[0044] 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, reselect, 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.

[0045] 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. In addition 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 a physical DL channel and a DL reference signal 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 a physical UL channel and / or UL reference signal 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 further 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.

[0046] 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., TRP 107-1, 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 further include an RRC controller 156 to implement procedures and messaging at the RRC sublayer of the protocol communication stack.

[0047] 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 (DU) 174. The CU 172 includes processing hardware, such as one or more general-purpose processors (e.g., CPUs) and a computer-readable memory storing machine-readable instructions executable on the general-purpose processors, and / or a dedicated processing unit. 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.

[0048] Each DU in DU 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 one or more general-purpose processors, and / or dedicated processing units. For example, the processing hardware may include: a MAC controller (e.g., MAC controllers 132, 142) configured to manage or control one or more MAC operations or processes (e.g., random access processes), and / or an RLC controller configured to manage or control one or more RLC operations or processes. The processing hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or processes.

[0049] 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.

[0050] 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).

[0051] 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 requested service of 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 174 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 the bearer context management function.

[0052] Figure 2A An example protocol stack 200 is shown in a simplified manner, according to which a UE 102 can communicate with an eNB / ng-eNB or a gNB (e.g., one or both of base stations 104, 106).

[0053] 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 may provide data transfer services. Figure 2A As shown, both EUTRA and NR stacks are supported to support switching between EUTRA and NR base stations and / or support dual connectivity (DC) through EUTRA and NR interfaces. Figure 2A As shown, the UE 102 can support the layering of NR PDCP 210 above the EUTRA RLC 206A, and the layering of SDAP sublayer 212 above the NR PDCP sublayer 210.

[0054] 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 above 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). Unless the difference between SDUs and PDUs is relevant, for simplicity, this disclosure refers to both SDUs and PDUs as "packets."

[0055] On the control plane, for example, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide the RRC sublayer ( Figure 2AThe NR PDCP sublayer 210 may provide a signaling radio bearer (SRB) to exchange 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 SDAP PDUs, IP packets, or Ethernet packets.

[0056] 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.

[0057] Figure 3A Detailed structure 300A of the NR layer 2 protocol stack 200 or 250 of the base station 104 or 106 is shown. PHY 202 ( Figure 3A The MAC sublayer 204 includes a transmission channel provided by the MAC sublayer 204 (not shown). The MAC sublayer 204 includes a scheduling and / or priority handling function for scheduling and 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 a specific user device. The MAC sublayer 204 further 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 segmentation and automatic repeat request (ARQ) functions for DL ​​data and UL data transmitted 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.

[0058] Figure 3B A detailed structure 300B of the NR layer 2 protocol stack 200 or 250 for the UE 102 is shown, which is similar to the structure 300A. 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 a logical channel prioritization and multiplexing function 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 a segmentation and automatic repeat request (ARQ) function for DL ​​data and UL data transmitted with the base station 104 and / or 106. 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 flow to the upper layer.

[0059] FIG. 4A to FIG. 4C FIG. 1 shows a method for implementing a specific CC in a UE 102, a base station 104 or 106, or a DU 174 of a base station 104 or 106. y Different implementations of HARQ entities for multi-TRP (mTRP) operation on (e.g., UL CC or DL ​​CC).

[0060] 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.

[0061] Next, Figure 4B A further implementation of a HARQ entity 400B is depicted which is 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, wherein each group is used for communication with a specific TRP.

[0062] Next, Figure 4C An implementation of a HARQ entity 400C (eg, HARQ entity k) similar to the HARQ entity 400A is depicted. The difference between the implementations of the HARQ entities 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.

[0063] Next, refer to FIG. 5A to FIG. 5E To discuss the Figure 1A The various components of mTRP are presented in several example scenarios related to mTRP operation. FIG. 5A to FIG. 5E Possibly identical events are marked with the same reference numerals.

[0064] 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 (e.g., periodically) 504, 506 one or more synchronization signal blocks (SSBs) via TRP 107-1 and broadcasts 508, 510 system information. 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 further 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 receives 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 uses one of the SSBs to perform downlink synchronization with the base station 104 on the cell 124 via the TRP 107-1 and receives 508, 510 system information via the TRP 107-1 based on the SSB.

[0065] Later, 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 event that the RSRP for 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. Then, the UE 102 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 parameter included in the system information (e.g., SIB1). In some implementations, the random access configuration parameter indicates 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.

[0066] 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 is received from the base station 104 that updates the first TA value. 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.

[0067] 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 a first random access preamble received from the UE 102 or based on the first random access preamble, 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.

[0068] Blocks 512, 514, 516, 518, and 520 are Figure 5A It is collectively referred to as the random access process 590.

[0069] 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 further implementations, 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 the 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 transmitted between the UE 102 and the base station 104. In further implementations, after performing the RRC connection establishment procedure or the 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.

[0070] 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 RRCReconfigurationComplete message) to the base station 104 via TRP 107-1. In some implementations, the CSI resource configuration includes configuring configuration parameters of 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 configuring configuration parameters of 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 to configure 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 reporting 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 reporting configuration configures periodic or semi-persistent reporting, or the CSI reporting 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.

[0071] 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-ResourceConfig IE, and / or CSI-ReportConfig IE.

[0072] Boxes 536, 538, 540, 542, 544, and 546 are Figure 5A The process is collectively referred to as CSI resource configuration and CSI reporting process 594.

[0073] 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.

[0074] 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 further 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.

[0075] In some implementations, base station 104 and UE 102 use Figure 4A , Figure 4B or Figure 4C The HARQ entity in performs DL communication with base station 104 via TRP 107-1 and TRP 107-2 at event 556. In some cases, such as in Figure 4B In the case of the HARQ entity 400B, the DL configuration parameters of events 548 and 550 include HARQ configuration parameters. The HARQ configuration parameters configure the first group of HARQ process IDs and the second group of HARQ process IDs. In some cases, the first group of HARQ process IDs and the second group of HARQ process IDs are used for TRP 107-1 and TRP 107-2, respectively. The first group of HARQ process IDs and the second group of HARQ process IDs identify the first group of HARQ processes of the HARQ entity and the second group of HARQ processes of the HARQ entity, respectively. In some implementations, none of the first group of HARQ process IDs and the second group of HARQ process IDs are the same. In other implementations, some of the first group of HARQ process IDs and the second group of HARQ process IDs are the same, and others are different.

[0076] In some implementations, the base station 104 sends one or more MAC control elements (CEs) or DCIs to the UE 102 to change or update one or more HARQ process IDs in the first group of HARQ process IDs. 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 group of HARQ process IDs. In some alternative implementations, the base station 104 does not configure the first group of HARQ process IDs and the second group of HARQ process IDs in the DL configuration parameters. In some implementations, the base station 104 determines the first group of HARQ process IDs and the second group of HARQ process IDs for mTRP operation based on pre-configuration. In a further implementation, the first group of HARQ process IDs and the second group of HARQ process IDs are specific, predetermined IDs (e.g., as specified in the 3GPP specification). In a further implementation, the base station 104 determines the first group of HARQ process IDs and the second group of HARQ process IDs based on rules.

[0077] In some implementations, when the base station 104 determines that the UE 102 is to be scheduled 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 the UL grant to receive the DL transmission from the base station 104. Similarly, when the base station 104 determines that the UE 102 is to be scheduled 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.

[0078] 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 higher). In some implementations, the base station 104 determines, based on the at least one first capability, DL configuration parameters to be 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.

[0079] In some implementations, the one or more capabilities include at least one second capability. In some such implementations, the at least one second capability indicates that the UE 102 supports multiple UL transmission timings for mTRP operation with the serving cell (i.e., operation of two or more TAs). In further implementations, the at least one second capability indicates that the UE 102 supports multiple UL transmission timings (for mTRP operation) with the serving cell and the 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, the at least one second capability includes several UL transmission timings (for mTRP operation) supported by the UE 102 with the serving cell and / or across all serving cells configured / activated for the UE 102. In further implementations, the at least one second capability does not include several UL transmission timings (for mTRP operation) and indicates that the UE 102 supports a default number (e.g., 2) of UL transmission timings. In some implementations, the base station 104 determines the UL configuration parameters to be configured for UL communication with the base station 104 via TRP 107-2 based on the 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.

[0080] 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.

[0081] 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 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., a UECapabilityEnquiry message) from the base station and sends a UE capability information message (e.g., a 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 may be 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 may be an F1 Application Protocol (F1AP) message.

[0082] In some implementations, the base station 104 may include in the RRC reconfiguration message random access configuration parameters 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-ConfigDedicated-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 for the RRCReconfiguration message in the RRCReconfiguration message without including the ReconfigurationWithSync IE and without encapsulating the RACH configuration or random access configuration parameters in the ReconfigurationWithSync IE. If the base station 104 uses the ReconfigurationWithSync 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.

[0083] 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 a further 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).

[0084] In some implementations, the UE 102 initiates a random access procedure 598 in response to receiving the field or IE before sending 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 further implementations, 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 order is received from the base station (e.g., events 558, 560, 559, 561).

[0085] Blocks 548, 550, 552, 554, and 556 are Figure 5A This is collectively referred to as the TRP configuration process 596A.

[0086] 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 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 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 a second preamble ID and a 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 the 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 using 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.

[0087] In some implementations, the base station 104 starts a second TAT to maintain second UL synchronization for UL and / or DL ​​communication 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.

[0088] Boxes 566, 568, 570, 572, and 574 are Figure 5A It is collectively referred to as the random access process 598.

[0089] In some implementations, the UE 102 suspends communication (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 a UL beam or RS (i.e., toward a TRP) and transmit 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 communication with the BS via the TRP 107-1 and TRP 107-2 according to the first TA value and the second TA value, respectively.

[0090] In some implementations, the base station 104 and the UE 102 use a HARQ entity (e.g., Figure 4A , Figure 4B or Figure 4C ) performs UL communication with base station 104 via TRP 107-1 and TRP 107-2 at event 576. In some cases (e.g., using Figure 4BIn an exemplary HARQ entity), the UL configuration parameters of events 548 and 550 include HARQ configuration parameters. The HARQ configuration parameters configure a first group of HARQ process IDs and a second group of HARQ process IDs. In some cases, the first group of HARQ process IDs and the second group of HARQ process IDs are used for TRP 107-1 and TRP 107-2, respectively. The first group of HARQ process IDs and the second group of HARQ process IDs identify a first group of HARQ processes of the HARQ entity and a second group of HARQ processes of the HARQ entity, respectively. In some implementations, none of the first group of HARQ process IDs and the second group of HARQ process IDs are the same. In other implementations, some of the first group of HARQ process IDs and the second group of HARQ process IDs are the same, and others are different.

[0091] 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 group of HARQ process IDs. In some further 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 group of HARQ process IDs. In some alternative implementations, the base station 104 does not configure the first group of HARQ process IDs and the second group of HARQ process IDs in the UL configuration parameters. In some implementations, the base station 104 determines the first group of HARQ process IDs and the second group of HARQ process IDs for mTRP operation based on preconfiguration. In a further implementation, the first group of HARQ process IDs and the second group of HARQ process IDs are specified sets (e.g., as specified in the 3GPP specification). In a further implementation, the base station 104 determines the first group of HARQ process IDs and the second group of HARQ process IDs based on rules.

[0092] In some implementations, when the base station 104 determines that the UE 102 is to be scheduled 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 that the UE 102 is to be scheduled 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.

[0093] 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, the UE 102 sends a random access preamble to the base station 104 via TRP 107-2 at event 566. 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 according to 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.

[0094] In some implementations, the PDCCH command is a DCI. The base station 104 generates a DCI and a CRC for the DCI, scrambles the CRC using the 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 a time and / or frequency resource for the PDCCH and sends the DCI and the scrambled CRC on the time and / or frequency resource.

[0095] 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 further implementations, the base station 104 determines or decodes the SSB index based on a radio resource (e.g., a PUCCH resource) 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 a CSI report 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., a PUCCH resource) for the UE 102 to send a CSI report 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.

[0096] 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 or decodes the CSI-RS index indicated in the CSI report. In further implementations, the base station 104 determines 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 a CSI report 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 a CSI report for each of the CSI-RSs. In some implementations, UE 102 determines a time / frequency resource and / or a RACH opportunity based on the CSI-RS (e.g., as indicated in the RS index) and a random access configuration parameter in the RRC reconfiguration message received by UE 102 at event 550. UE 102 sends a second random access preamble on the time / frequency resource and / or RACH opportunity. In some implementations, the random access configuration parameter indicates one or more associations between the CSI-RS and the RACH opportunity and / or the time / frequency resource.

[0097] 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 sends the second random access preamble to TRP 107-2 using the determined transmission characteristics. In some examples, UE 102 uses reception characteristics for receiving 564 the RS identified by the RS index to derive the transmission characteristics. In some implementations, the transmission characteristics include phase, power and / or transmission precoders. In some implementations, UE 102 further uses DL and / or UL configuration parameters of event 550 to determine the transmission characteristics. In further 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 the transmission characteristics (e.g., spatial transmission filters / parameters) based on or by reference to the RS index in the PDCCH order, and sends the second random access preamble to TRP 107-2 using the determined transmission characteristics.

[0098] 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.

[0099] 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 the reception characteristics for receiving 564 RS.

[0100] Although TRP 107-2 is used in scenario 500A, the above description can be applied to scenarios using TRP 107-3 instead of TRP 107-2. In such scenarios, after successfully completing the random access procedure with the base station via TRP 107-3 and cell 125, similar to process 598, 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.

[0101] In some scenarios or implementations, the base station 104 sends a third TA command including a first new TA value for updating the first TA value to the UE 102 via the TRP 107-1 or the TRP 107-2. In some implementations, the third TA command is a MAC control element (CE). The UE 102 applies the first new TA value for the first UL synchronization and restarts the first TAT of the UE 102 in response to receiving the third TA command. 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 for updating the second TA value to the UE 102 via the TRP 107-1 or the TRP 107-2. In some implementations, the fourth TA command is a MAC CE. The UE 102 applies the second new TA value for the second UL synchronization and restarts the second TAT in response to receiving the fourth TA command. In some scenarios or implementations, the base station 104 sends a single TA command including a first new TA value and a second new TA value for updating the first TA value and the second TA value, respectively, to the UE 102 via the TRP 107-1 or the TRP 107-2. 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).

[0102] 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, TRP107-2 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, second, third, and fourth thresholds are the same or different.

[0103] Go to Figure 5B, scenario 500B is similar to scenario 500A, and the differences are described below. In scenario 500B, base station 104 sends 549, 551 RRC reconfiguration messages 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., for configuring or implementing 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 TRP 107-1, and the other RRC reconfiguration message includes UL configuration parameters for UL communication with the base station 104 via TRP 107-2. In response, the UE 102 sends 582, 584 an RRC reconfiguration complete message to the base station 104 via TRP 107-1. 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.

[0104] 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.

[0105] Next reference Figure 5C , scenario 500C is similar to scenarios 500A and 500B, and the differences are described below.

[0106] 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 other 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 RRC reconfiguration to the UE 102 via TRP 107-2 instead of TRP 107-1.

[0107] Boxes 549, 551, 552, 554, 556, 579, 581, 582, and 584 are Figure 5C It is collectively referred to as TRP configuration process 596C.

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

[0109] After UE 102 performs the 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.

[0110] Next reference Figure 5E , scenario 500E is similar to scenarios 500A, 500B, 500C, and 500D, and the differences are described below.

[0111] 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, 599 with base station 104 via TRP 107-2, similar to events 558, 560.

[0112] Figure 6 A to Fig.15 1 is a flow chart depicting an example method implemented by a RAN node (e.g., base station 104 / 106 or DU 174) to enable communication of a UE (e.g., UE 102) through multiple TRPs. In some examples, 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.

[0113] Go to Figure 6 , a RAN node (e.g., base station 104 / 106 or DU 174) implements example method 600 to manage multiple UL synchronizations for communication with a UE (e.g., UE 102) via multiple TRPs (e.g., TRP 107-1, TRP 107-2 and / or TRP 107-3).

[0114] Method 600 begins at block 602, where a RAN node performs DL and UL communications with a UE (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 RAN node sends a configuration to the UE that implements operation of two TA values ​​(e.g., events 548, 550, 596A, 578, 580, 596B, 579, 581, 596C). At box 606, the RAN node sends to the UE a first TA value for a first UL synchronization between the UE and the first TRP (e.g., events 516, 518, 590). At box 608, the RAN node sends to the UE a second TA value for a second UL synchronization between the UE and the second TRP (e.g., events 570, 572, 598, 571, 573, 599). The process continues to box 610 and / or box 612. At box 610, the RAN node determines whether the first UL synchronization is invalid or the second UL synchronization is invalid. If the RAN node determines that the first UL synchronization is invalid, the process continues to box 612, where the RAN node stops scheduling the UE to send UL transmissions to the first TRP. In some such cases, the RAN continues to schedule the UE to send UL transmissions to the second TRP. Otherwise, if the RAN node determines that the second UL synchronization is invalid, the process continues to box 614, where the RAN node stops scheduling the UE to send UL transmissions to the second TRP.

[0115] In some implementations, the RAN node continues to schedule the UE to send UL transmissions to the first TRP at box 614. In some implementations, the RAN node continues to schedule the UE to send UL transmissions to the second TRP at box 612. In some implementations, if the RAN node determines that both the first and second UL synchronizations are invalid, the RAN node stops scheduling the UE to send UL transmissions to the first TRP and stops scheduling the UE to send UL transmissions to the second TRP. In some implementations, the above UL transmissions include PUSCH transmissions, SRS transmissions, and / or CSI transmissions.

[0116] In some implementations, the RAN node maintains (e.g., manages) first UL synchronization and second UL synchronization with the UE by sending a first TA value and a second TA value to the UE, 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 RAN node 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 RAN node on a serving cell and a non-serving cell, respectively. In some implementations, the non-serving cell is neither a primary cell nor a secondary cell.

[0117] In some implementations, the base station sends a first TA value to the UE in a first random access response, a first MAC CE, or a first MAC PDU. In some implementations, the base station sends a second TA value to the UE in a second random access response, a second MAC CE, or a second MAC PDU. In some implementations, the first MAC CE and the second MAC CE are the same MAC CE. In a further 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 a further implementation, the first MAC PDU and the second MAC PDU are different MAC PDUs. In some implementations, the RAN node sends an incremental value of the second TA value to the UE instead of the second TA value, wherein the second TA value is equal to the sum of the first TA value and the incremental value.

[0118] In some implementations, if the first UL synchronization is invalid, the RAN node stops sending or scheduling DL transmissions (e.g., PDCCH transmissions and / or PDSCH transmissions) to the UE via the first TRP. In some alternative implementations, if the first UL synchronization is invalid, the RAN node continues to send or schedule DL transmissions to the UE via the first TRP. In some implementations, if the second UL synchronization is invalid, the RAN node stops sending or scheduling DL transmissions to the UE via the second TRP. In some alternative implementations, if the second UL synchronization is invalid, the RAN node continues to send or schedule DL transmissions to the UE via the second TRP.

[0119] Fig. 7A is similar to Figure 6Flowchart of an example method 700A of method 600 of the embodiment of the present invention, wherein blocks 702 to 710 are the same as blocks 602 to 610, respectively. If the RAN node determines that the first UL synchronization is invalid, the flow proceeds to block 712, where the RAN node flushes the HARQ buffers of the first set of HARQ processes, which the RAN node uses to send the first PDSCH transmission to the UE via the first TRP. Otherwise, if the RAN node determines that the second UL synchronization is invalid, the flow proceeds to block 714, where the RAN node flushes the HARQ buffers of the second set of HARQ processes, which the RAN node uses to send the second PDSCH transmission to the UE via the second TRP.

[0120] In some implementations, the RAN node refrains from flushing HARQ buffers for the first set of HARQ processes at block 714. In some implementations, the RAN node refrains from flushing HARQ buffers for the second set of HARQ processes at block 712. In some implementations, if the RAN node determines that both the first and second UL synchronizations are invalid, the RAN node flushes HARQ buffers for the first set of HARQ processes and the second set of HARQ processes that the RAN node uses to send the first PDSCH transmission and the second PDSCH transmission to the UE via the first TRP and the second TRP, respectively.

[0121] Figure 7B is a flow chart of an example method 700B similar to methods 600 and 700A, wherein blocks 702 to 708 are the same as blocks 602 to 608, respectively. At block 711, the RAN node determines whether the first UL synchronization and the second UL synchronization are invalid. If the RAN node determines that the first UL synchronization and the second UL synchronization are invalid, the flow proceeds to block 713, where the RAN node flushes the HARQ buffer of the HARQ process that the RAN node uses to send PUSCH transmissions via the first TRP and / or the second TRP. Otherwise, if the RAN node determines that the first UL synchronization and the second UL synchronization are valid, or the first UL synchronization or the second UL synchronization is invalid, the flow proceeds to block 715, where the RAN node refrains from flushing the HARQ buffer.

[0122] Fig. 8A is similar to Figure 6600, wherein blocks 802 to 810 are the same as blocks 602 to 610, respectively. If the RAN node determines that the first UL synchronization is invalid, the flow proceeds to block 812, where the RAN node clears the first configured UL grant configured to cause the UE to periodically send PUSCH transmissions to the first TRP. Otherwise, if the RAN node determines that the second UL synchronization is invalid, the flow proceeds to block 814, where the RAN node clears the second configured UL grant configured to cause the UE to periodically send PUSCH transmissions to the second TRP.

[0123] In some implementations, the RAN node refrains from clearing the first configured grant at block 814. In some implementations, the RAN node refrains from clearing the first configured grant at block 812. In some implementations, if the RAN node determines that both the first and second UL synchronizations are invalid, the RAN node clears the first configured UL grant and the second configured UL grant configured to cause the UE to periodically send PUSCH transmissions to the first TRP and the second TRP, respectively.

[0124] In some implementations, the RAN node sends to the UE at least one first configured grant configuration (e.g., ConfiguredGrantConfig IE) that configures a first UL grant. In some implementations, the RAN node sends to the UE at least one second configured grant configuration (e.g., ConfiguredGrantConfig IE) that configures a second UL grant.

[0125] Figure 8B is a flow chart of an example method 800B similar to methods 600, 700B, and 800A, wherein blocks 802 to 811 are respectively Figure 7B If the RAN node determines that the first UL synchronization and the second UL synchronization are invalid, the flow proceeds to block 813, where the RAN node performs the clearing actions described in blocks 812 and / or 814. Otherwise, if the RAN node determines that the first UL synchronization and the second UL synchronization are valid, or the first UL synchronization or the second UL synchronization is invalid, the flow proceeds to block 815, where the RAN node avoids performing the releasing actions described in blocks 812 and / or 814.

[0126] Fig. 9A is similar to Figure 6600, wherein blocks 902 to 910 are the same as blocks 602 to 610, respectively. If the RAN node determines that the first UL synchronization is invalid, the flow proceeds to block 912, where the RAN node releases the first PUCCH CSI resources and / or the first scheduling request resource configuration instance configured for the UE and associated with the first TRP. Otherwise, if the RAN node determines that the second UL synchronization is invalid, the flow proceeds to block 914, where the RAN node releases the second PUCCH CSI resources and / or the second scheduling request resource configuration instance configured for the UE and associated with the second TRP.

[0127] In some implementations, at box 914, the RAN node refrains from releasing the first PUCCH CSI resource and / or the first scheduling request resource configuration instance. In some implementations, at box 912, the RAN node refrains from releasing the second PUCCH CSI resource and / or the second scheduling request resource configuration instance. In some implementations, if the RAN node determines that both the first and second UL synchronizations are invalid, the RAN node releases the first PUCCH CSI resource and the second PUCCH CSI resource configured for the UE and associated with the first TRP and / or the second TRP. In some implementations, if the RAN node determines that both the first and second UL synchronizations are invalid, the RAN node releases the first and second scheduling request resource configuration instances configured for the UE and associated with the first TRP and / or the second TRP.

[0128] In some implementations, the RAN node sends to the UE at least one first CSI-ReportConfig IE configuring a first PUCCH CSI resource. In some implementations, the RAN node sends to the UE at least one second CSI-ReportConfig IE configuring a second PUCCH CSI resource. In some implementations, the RAN node sends to the UE at least one first PUCCH-Config IE configuring a first scheduling request resource configuration instance. In some implementations, the RAN node sends to the UE at least one second PUCCH-Config IE configuring a second scheduling request resource configuration instance.

[0129] Fig. 9B is a flow chart of an example method 900B similar to methods 600, 700B, and 900A, wherein blocks 902 to 911 are respectively Figure 7BIf the RAN node determines that the first UL synchronization and the second UL synchronization are invalid, the flow proceeds to block 913, where the RAN node performs the release actions described in blocks 912 and / or 914. Otherwise, if the RAN node determines that the first UL synchronization and the second UL synchronization are valid, or the first UL synchronization or the second UL synchronization is invalid, the flow proceeds to block 915, where the RAN node avoids performing the release actions described in blocks 912 and / or 914.

[0130] Fig. 10A is similar to Figure 6 1000A of method 600 of the present invention, wherein blocks 1002 to 1010 are the same as blocks 602 to 610, respectively. If the RAN node determines that the first UL synchronization is invalid, the flow proceeds to block 1012, where the RAN node releases the first SRS resource configuration instance configured for the UE and associated with the first TRP. Otherwise, if the RAN node determines that the second UL synchronization is invalid, the flow proceeds to block 1014, where the RAN node releases the second SRS resource configuration instance configured for the UE and associated with the second TRP.

[0131] In some implementations, the RAN node refrains from releasing the first SRS resource configuration instance at block 1014. In some implementations, the RAN node refrains from releasing the second SRS resource configuration instance at block 1012. In some implementations, if the RAN node determines that both the first and second UL synchronization are invalid, the RAN node releases the first SRS resource configuration instance and the second SRS resource configuration instance configured for the UE and associated with the first TRP and the second TRP, respectively.

[0132] In some implementations, the RAN node sends to the UE at least one first SRS-Resource IE configuring a first SRS resource configuration instance. In some implementations, the RAN node sends to the UE at least one second SRS-Resource IE configuring a second SRS resource configuration instance.

[0133] Fig. 10B is a flow chart of an example method 1000B similar to methods 600, 700B, and 1000A, wherein blocks 1002 to 1011 are respectively Figure 7BIf the RAN node determines that the first UL synchronization and the second UL synchronization are invalid, the flow proceeds to block 1013, where the RAN node performs the release actions described in blocks 1012 and / or 1014. Otherwise, if the RAN node determines that the first UL synchronization and the second UL synchronization are valid, or the first UL synchronization or the second UL synchronization is invalid, the flow proceeds to block 1015, where the RAN node avoids performing the release actions described in blocks 1012 and / or 1014.

[0134] Fig.11A is similar to Figure 6 Flowchart of an example method 1100A of method 600 of the present invention, wherein blocks 1102 to 1110 are the same as blocks 602 to 610, respectively. If the RAN node determines that the first UL synchronization is invalid, the flow proceeds to block 1112, where the RAN node clears the first PUSCH resource configured for the UE and associated with the first TRP for semi-persistent CSI reporting. Otherwise, if the RAN node determines that the second UL synchronization is invalid, the flow proceeds to block 1114, where the RAN node clears the second PUSCH resource configured for the UE and associated with the second TRP for semi-persistent CSI reporting.

[0135] In some implementations, the RAN node refrains from releasing the first PUSCH resource at block 1114. In some implementations, the RAN node refrains from releasing the second PUSCH resource at block 1112. In some implementations, if the RAN node determines that both the first and second UL synchronizations are invalid, the RAN node clears the first PUSCH resource and the second PUSCH resource configured for the UE and associated with the first TRP and the second TRP, respectively.

[0136] In some implementations, the RAN node sends to the UE at least one first CSI-ReportConfig IE configuring the first PUSCH resource. In some implementations, the RAN node sends to the UE at least one second CSI-ReportConfig IE configuring the second PUSCH resource.

[0137] Fig. 11B is a flow chart of an example method 1100B similar to methods 600, 700B, and 1100A, wherein blocks 1102 to 1111 are respectively Figure 7BIf the RAN node determines that the first UL synchronization and the second UL synchronization are invalid, the flow proceeds to block 1113, where the RAN node performs the release actions described in blocks 1112 and / or 1114. Otherwise, if the RAN node determines that the first UL synchronization and the second UL synchronization are valid, or the first UL synchronization or the second UL synchronization is invalid, the flow proceeds to block 1115, where the RAN node avoids performing the release actions described in blocks 1112 and / or 1114.

[0138] Fig.12 is similar to Figure 6 1200 , wherein blocks 1202 to 1210 are the same as blocks 602 to 610, respectively. If the RAN node determines that the first UL synchronization is invalid, the process proceeds to block 1212, where the RAN node sends a random access trigger command to the UE for triggering the UE to send a random access preamble to the first TRP. Otherwise, if the RAN node determines that the second UL synchronization is invalid, the process proceeds to block 1214, where the RAN node sends a random access trigger command to the UE for triggering the UE to send a random access preamble to the second TRP (e.g., events 558, 560, 559, 561).

[0139] In some implementations, if the RAN node determines that both the first and second UL synchronizations are invalid, the RAN node sends a random access trigger command to the UE for triggering the UE to send a random access preamble to the first TRP. In some such implementations, the RAN node avoids triggering the UE to send a random access preamble to the second TRP.

[0140] Go to Fig.13 , a RAN node (e.g., base station 104 / 106 or DU 174) implements example method 1300 to determine whether one of a plurality of UL synchronizations for communication with a UE (e.g., UE 102) via a plurality of TRPs (e.g., TRP 107-1, TRP 107-2, and / or TRP 107-3) is invalid. Example method 1300 may be applied to other embodiments herein (e.g., Figures 6 to 12 ), to determine whether the first UL synchronization is valid or the second UL synchronization is valid.

[0141] Blocks 1302 to 1308 are respectively Figure 6. At block 1310, the RAN node starts or restarts the first TAT to maintain first UL synchronization with the UE when sending the first TA value to the UE (e.g., when sending the first TA value to the UE, after sending the first TA value to the UE, or in response to sending the first TA value to the UE). At block 1312, the RAN node starts or restarts the first TAT to maintain second UL synchronization with the UE when sending the second TA value to the UE. At block 1314, the RAN node detects or determines whether the first TAT expires or the second TAT expires. If the RAN node detects or determines that the first TAT expires, the process proceeds to block 1316. At block 1316, the RAN node determines that the first UL synchronization is invalid. Otherwise, if the RAN node detects or determines that the second TAT expires, the process proceeds to block 1318. At block 1318, the RAN node determines that the second UL synchronization is invalid.

[0142] In some implementations, the RAN node determines that the first UL synchronization and the second UL synchronization are invalid if both the first TAT and the second TAT expire.

[0143] Go to Fig.14 , a RAN node (e.g., base station 104 / 106 or DU 174) implements example method 1400 to determine whether one of a plurality of UL synchronizations for communication with a UE (e.g., UE 102) via a plurality of TRPs (e.g., TRP 107-1, TRP 107-2, and / or TRP 107-3) is invalid. Example method 1400 may be applied to other embodiments described herein (e.g., Figures 6 to 12 ), to determine whether the first UL synchronization is valid or the second UL synchronization is valid.

[0144] Blocks 1402 to 1408 and blocks 1416 to 1418 are respectively Figure 6 Boxes 602 to 608 and Fig.13 1316 to 1318 of . At block 1410, the RAN node receives an indication from the UE. At block 1412, the RAN node determines whether the indication indicates that the first UL synchronization is invalid or the second UL synchronization is invalid. If the RAN node determines that the indication indicates that the first UL synchronization is invalid, the flow proceeds to block 1416. Otherwise, if the RAN node determines that the indication indicates that the second UL synchronization is invalid, the flow proceeds to block 1418.

[0145] In some implementations, if both the first TAT and the second TAT expire, the RAN node determines that the first UL synchronization and the second UL synchronization are invalid. In some implementations, the indication is an existing RRC message (e.g., a UEAssistanceInformation message) or a new RRC message (e.g., newly defined to indicate that a specific UL synchronization is invalid). In other implementations, the indication is a MAC CE. In yet other implementations, the indication is a PUCCH transmission.

[0146] Go to Fig.15 , a RAN node (e.g., base station 104 / 106 or DU 174) implements example method 1500 to manage multiple UL synchronizations for communication with a UE (e.g., UE 102) via multiple TRPs (e.g., TRP 107-1, TRP 107-2 and / or TRP 107-3).

[0147] Blocks 1502 to 1508 are respectively Figure 6 At block 1510, the RAN node starts or restarts a single TAT to maintain first UL synchronization and second UL synchronization with the UE. At block 1512, the RAN node detects or determines that the TAT expires. At block 1514, the RAN node performs actions described in blocks 612 / 614, 713, 813, 913, 1013, 1113, and / or 1212 in response to the TAT expiration.

[0148] In some implementations, the RAN node starts or restarts a single TAT when sending or determining to send a first TA value, a second TA value, or both the first TA value and the second TA value (e.g., when sending or determining to send the first TA value, the second TA value, or both the first TA value and the second TA value, in response to sending or determining to send the first TA value, the second TA value, or both the first TA value and the second TA value, or after sending or determining to send the first TA value, the second TA value, or both the first TA value and the second TA value) to maintain first UL synchronization and second UL synchronization with the UE.

[0149] against Figure 6 The examples and implementations described can be applied to FIG. 7A to FIG. 15 Similarly, for Figures 6 to 15 Examples and implementations of some of the described embodiments may be applied to Figures 6 to 15 Other embodiments of the present invention.

[0150] The following description can be applied to the above description.

[0151] Some further implementations or descriptions related to a UE (eg, UE 102) performing a random access procedure and / or performing multi-TA operation are described below.

[0152] 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 sent by the base station to a UE (e.g., UE 102) for UL transmission 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 sent by the base station to the UE 102 to perform DL transmission via the TRP identified by the TRP identifier. In some implementations, the DL configuration includes DCI sent on the PDCCH, and / or CSI resource configuration, PDSCH configuration, and / or 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 CSI-RS transmission, SSB transmission, PDSCH transmission, and / or PDCCH transmission.

[0153] In other implementations, the base station does not send a TRP identifier to the UE, and an implicit indication is used 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.

[0154] In some implementations, the base station configures the UE with a first TAG and a second TAG 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 to the UE, respectively including a first TAG configuration and a second TAG configuration for configuring the first TAG and the second TAG. In some implementations, the first TAG configuration and the second TAG configuration include a first TAG ID and a second TAG ID for identifying the first TAG and the second TAG, respectively. In some implementations, the first TAG configuration and the second TAG configuration include a timer value of a first TAT and a timer value of a 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 and second RRC messages 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 a first TRP or a first TRP identifier and / or an identifier value. In some implementations, the first TAG is associated with a first 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 a first RRC message. 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 is associated with a first service cell or a non-service cell, and the base station indicates or configures the association in a second RRC message.

[0155] In other implementations, the base station configures a single TAG for UL transmission to a first TRP and a second TRP for the UE. 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 for configuring the TAG to the UE. 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 for the first TAT and a timer value for the second TAT. In a further implementation, the TAG configuration includes a timer value 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) a first TRP or a first TRP identifier and / or an identifier value and (ii) a second TRP or a second TRP identifier. In some implementations, the TAG is associated with a first serving cell operated by the first TRP and configured for the UE. In some implementations, the TAG is associated with an additional serving 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 first serving cell or a non-serving cell, and the base station indicates or configures the association in a second RRC message.

[0156] In some implementations, the base station configures a first serving 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 the first serving cell or the first TRP. In a further 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 the first serving cell to be associated with the second TRP or the second TRP identifier and / or identifier value. In other implementations, the second TAG is associated with the non-serving cell, and the base station indicates or configures the association in the second RRC message. In some implementations, the base station configures the non-serving cell associated with the second TRP or the second TRP identifier and / or identifier value. In some implementations, the base station configures the second CORESET to be associated with the first serving cell, the non-serving cell, or the second TRP. In a further 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 the DCI from the base station, which implies that the UE monitors the PDCCH or receives the DCI from the base station (i.e., from the second TRP) via the second TRP. In some such implementations, the UE determines that CORESETPoolIndex #1 indicates a specific TRP (i.e., the second TRP).

[0158] In some implementations, in addition to the TAG ID described above, the base station is further configured with a first ID for identifying a first TA value for the UE. In some implementations, the base station includes the first ID in the RRC message described above. In a further 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 is further configured with a second ID for identifying a second TA value for the UE. In some implementations, the base station includes the second ID in the RRC message described above. In a further 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 further implementations, the base station configures or indicates to the UE a second index for / 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 implementations, the UE performs one of the following actions: (i) triggering or performing a contention-based or contention-free RA process associated with a first index; or (ii) triggering or performing a contention-based or contention-free RA process intended for a first TRP, a first TAG, a first TAT, or a first TA value.

[0162] In some implementations, the UE performs one of the following actions: (i) triggering or performing a contention-based or contention-free RA procedure associated with the second index; or (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. In some such implementations, some examples include a RA procedure that includes the step of sending a RA preamble to the second TRP, such as at least Figure 6 , Fig. 7A , Figure 7B , Fig. 8A , Figure 8B and as described in FIG. 9 .

[0163] In some implementations, the UE receives a configuration from a base station for configuring or indicating a first set of RA resources. In some implementations, the first set of RA resources includes a first set of RA preambles and / or a first set of SSB indexes. In a further implementation, the first set of RA resources is associated with a first set of SSB indexes. In a further implementation, the first set of RA resources includes a first set of UL resources and / or authorization for sending MSG A. In some implementations, the first set of RA resources is associated with or used for a first TRP or a first index. In some implementations, the configuration for configuring or indicating the first set of RA resources includes or is associated with the first index.

[0164] In some implementations, the UE receives a configuration from the base station for configuring or indicating a second group of RA resources. In some implementations, the second group of RA resources includes a second group of RA preambles and / or a second group of SSB indexes. In a further implementation, the second group of RA resources is associated with a second group of SSB indexes. In a further implementation, the second group of RA resources includes a second group of UL resources and / or a grant for sending MSG A. In some implementations, the second group of RA resources is associated with or used for a second TRP or a second index. In some implementations, the configuration for configuring or indicating the second group of RA resources includes or is associated with a second index.

[0165] Some examples for configuring or indicating the configuration of the first group of RA resources include UL configuration parameters in procedures 596A / 596B / 596C. Some examples for configuring or indicating the configuration of the second group of RA resources include UL configuration parameters in procedures 596A / 596B / 596C.

[0166] In some cases, when a RA procedure is associated with or intended for one of the following or if the RA procedure is associated with or intended for one of the following: (a) a first index, (b) a first TRP, (c) a first TAG, (d) a first TA value, and / or (e) a first TAT, at least one of the following is true: (i) MSG 0 or a PDCCH order for the RA procedure (received by the UE from the base station) indicates or is associated with the first TRP, wherein, in some implementations, the RA procedure is a contention-free RA procedure; (ii) MSG 1 or MSG A for the RA procedure (sent by the UE to the base station) indicates or is associated with the first TRP, wherein, in some implementations, the UE sends MSG 1 or MSG A using a first group of RA resources; (iii) MSG 2 or MSG B for the RA procedure (received by the UE from the base station) indicates or is associated with the first TRP; (iv) MSG 3 (sent by the UE to the base station) or MSG 4 for the RA procedure (received by the UE from the base station) indicates a first TRP or is associated with a first TRP; (v) MSG 0 or a PDCCH command for a RA process (received by the UE from the base station) indicates a first index or is associated with a first index, wherein, in some implementations, the RA process is a contention-free RA process; (vi) MSG 1 or MSG A for a RA process (sent by the UE to the base station) indicates a first index or is associated with a first index, wherein, in some implementations, the UE uses a first group of RA resources to send MSG 1 or MSG A; (vii) MSG 2 or MSG B for a RA process (received by the UE from the base station) indicates a first index or is associated with a first index; and / or (viii) MSG 3 for a RA process (sent by the UE to the base station) or MSG 4 (received by the UE from the base station) indicates a first index or is associated with a first index.

[0167] In some cases, when the RA procedure is associated with or intended for one of the following or if the RA procedure is associated with or intended for one of the following: (a) a second index, (b) a second TRP (e.g., an RA procedure including the step of sending an RA preamble to the second TRP, such as at least Figure 6 , Fig. 7A , Figure 7B , Fig. 8A , Figure 8Band Figure 9), (c) a second TAG, (d) a second TA value and / or (e) a second TAT, then at least one of the following is true: (i) MSG 0 or a PDCCH command for the RA process (received by the UE from the base station) indicates a second TRP or is associated with a second TRP, wherein, in some implementations, the RA process is a contention-free RA process; (ii) MSG 1 or MSG A for the RA process (sent by the UE to the base station) indicates a second TRP or is associated with a second TRP, wherein, in some implementations, the UE uses a second group RA resource to send MSG 1 or MSG A; (iii) MSG 2 or MSG B for the RA process (received by the UE from the base station) indicates a second TRP or is associated with a second TRP; (iv) MSG 3 for the RA process (sent by the UE to the base station) or MSG 4 for the RA process (received by the UE from the BS) indicates a second TRP or is associated with a second TRP; (v) MSG for the RA process (vi) MSG 1 or MSG A for the RA process (sent by the UE to the base station) indicates the second index or is associated with the second index, wherein, in some implementations, the UE uses a second group RA resource to send MSG 1 or MSG A; (vii) MSG 2 or MSG B for the RA process (received by the UE from the base station) indicates the second index or is associated with the second index; and / or (viii) MSG 3 (sent by the UE to the base station) or MSG 4 (received by the UE from the base station) for the RA process indicates the second index or is associated with the second index.

[0168] Generally speaking, the description of one of the above figures may apply to another of the above figures. The events or boxes described above may be optional or omitted. For example, the events or boxes with dashed lines in the figures may be optional or omitted. In some cases, if the events or boxes with solid lines in the figures are not necessary, the events or boxes may still be optional or omitted. In some implementations, the boxes in different figures may be combined. In some implementations, "message" is used and "information element (IE)" may be used to replace "message". In some implementations, "IE" is used and "field" may be used to replace "IE". In some implementations, "configuration" or "configuration parameter" may be used to replace "configuration". In some implementations, "according to" may be replaced by "using". "mTRP operation" and "mTRP communication" may be interchangeable. In some implementations, "through the second TRP to the base station", "through the second TRP from the base station", "through the second TRP with the base station" may be replaced by "to the second TRP", "from the second TRP", "with the second TRP" respectively.

[0169] 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. Further, in some cases, the user device can be embedded in an electronic system, such as a head unit or an advanced driver assistance system (ADAS) of a vehicle. Still further, the user device can operate 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.

[0170] 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 particular manner. A hardware module may include dedicated circuitry or logic that is permanently configured to perform certain operations (e.g., as a dedicated processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC)). A hardware module may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations (e.g., as contained in a general-purpose processor or other programmable processor). The decision to implement a hardware module with a dedicated and permanently configured circuitry or with a temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.

[0171] 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 Radio Access Network RAN ​​node and comprising: sending, to a user equipment UE, a first timing advance TA value for managing synchronization of a first transmission between the UE and a first transmission and reception point TRP of the RAN node; sending, to the UE, a second TA value for managing synchronization of a second transmission between the UE and a second TRP of the RAN node; ceasing to schedule the first transmission in response to determining that the synchronization of the first transmission is invalid; as well as In response to determining that the synchronization of the second transmission is invalid, scheduling the second transmission is stopped.

2. The method according to claim 1, wherein: Determining that the synchronization of the first transmission is invalid comprises: Receive a notification from the UE that a TA timer TAT associated with the first TRP has expired.

3. The method according to claim 2, wherein: The message is a UE assistance information message.

4. The method according to claim 2, wherein: The message is a dedicated Radio Resource Control message RRC message defined for reporting TAT expiration.

5. The method according to claim 2, wherein: The message is a Medium Access Control MAC Control Element CE.

6. The method according to claim 2, wherein: The message is a Physical Uplink Control Channel PUCCH indication.

7. A method according to any one of the preceding claims, wherein: The first transmission and the second transmission comprise uplink (UL) transmissions.

8. A method according to any one of the preceding claims, wherein: The first transmission and the second transmission comprise downlink (DL) transmissions.

9. The method according to any one of the preceding claims, further comprising: After stopping scheduling the first transmission and before stopping the second transmission, continuing to schedule the second transmission.

10. A method according to any one of the preceding claims, wherein: The first TRP is associated with a first TA group TAG, and The second TRP is associated with a second TAG.

11. A method according to any one of the preceding claims, wherein: The first TA value is associated with a first TCI state, and The second TA value is associated with a second TCI state.

12. The method according to any one of the preceding claims, further comprising: An indication is sent to the UE to enable use of multiple TA values.

13. A method according to any one of the preceding claims, wherein: Sending the first TA value includes: Send a MAC CE including the first TA value.

14. The method according to any one of claims 1 to 12, wherein: Sending the first TA value includes: sending a MAC protocol data unit PDU including the first TA value.

15. A radio access network RAN, comprising: Transceiver; as well as Processing hardware configured to implement a method according to any one of the preceding claims.

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