Managing uplink timing synchronization

Abstract

A user equipment (UE) starts or restarts (1147, 1153) a timing alignment timer of a target cell in response to obtaining (1159) a timing advance of the target cell from a radio access network (RAN) in a serving cell; receiving (113) a command for initiating a lower layer triggered mobility (LTM) cell change to the target cell; resetting (1141) a media access control (MAC) entity in response to the command; and keeping the timing alignment timer running when the MAC entity (1170) is restarted.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Provisional U.S. Patent Application No. 63 / 525,653, filed July 7, 2023, entitled “Managing Uplink Timing Synchronization,” the entire contents of which are hereby expressly incorporated herein by reference. Technical Field

[0003] This disclosure relates to wireless communications, and more specifically, to managing uplink synchronization between a user equipment (UE) and a radio access network (RAN). Background Technology

[0004] This background description is provided for the purpose of generally presenting the context of this disclosure. The work of the inventors whose names are mentioned (to the extent described in this background section) and aspects of the specification that might not have been considered prior art at the time of filing are neither expressly nor impliedly acknowledged as prior art to this disclosure.

[0005] In telecommunications systems, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as user plane data delivery, encryption, and integrity protection. For example, the PDCP layer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP specification TS 36.323) and New Radio (NR) (see 3GPP specification TS 38.323) provides Protocol Data Unit (PDU) sequencing in the uplink direction (from the user equipment (UE) to the base station) and in the downlink direction (from the base station to the UE). Furthermore, the PDCP sublayer provides Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs) to the Radio Resource Control (RRC) sublayer. Generally, the UE and base station can use SRBs to exchange RRC messages and Non-Access Stratum (NAS) messages, and can use DRBs to transmit data on the user plane.

[0006] UEs can use several types of SRBs and DRBs. When operating in dual connectivity (DC), the cell associated with the base station operating as the primary node (MN) defines a primary cell group (MCG), and the cell associated with the base station operating as the secondary node (SN) defines a secondary cell group (SCG). The so-called SRB1 resource carries RRC messages that, in some cases, include NAS messages on the dedicated control channel (DCCH), while the SRB2 resource supports RRC messages that include recorded measurement information or NAS messages, also on the DCCH but with a lower priority than the SRB1 resource. More generally, SRB1 and SRB2 resources allow the UE and MN to exchange MN-related RRC messages and embed SN-related RRC messages, and can also be referred to as MCG SRBs. SRB3 resources allow the UE and SN to exchange SN-related RRC messages and can be referred to as SCG SRBs. Split SRBs allow the UE to exchange RRC messages directly with the MN via lower-layer resources of the MN and SN. Furthermore, a DRB that uses only the lower-level resources of MN can be called an MCG DRB, a DRB that uses only the lower-level resources of SN can be called an SCG DRB, and a DRB that uses both the lower-level resources of MCG and SCG can be called a split DRB.

[0007] In some scenarios, a UE can simultaneously utilize the resources of multiple Radio Access Network (RAN) nodes (e.g., base stations, or components of distributed base stations) interconnected via backhaul. This type of connection is called Multiple Radio Dual Connectivity (MR-DC) when these network nodes support different Radio Access Technologies (RATs). When the UE operates under MR-DC, one base station operates as the primary node (MN) covering the primary cell (PCell), while another base station operates as the secondary node (SN) covering the primary secondary cell (PSCell). The UE communicates with the MN (via PCell) and the SN (via PSCell). In other scenarios, the UE utilizes the resources of one base station at a time. One base station and / or the UE determines that the UE should establish a radio connection with another base station. For example, one base station may determine to hand over the UE to a second base station and initiate a handover procedure.

[0008] When a UE moves from the coverage area of ​​one cell in the RAN to the coverage area of ​​another cell, the UE and the RAN must perform a serving cell change at some point. For this purpose, the RAN configures the UE to send Layer 3 (L3) measurements. Using the L3 measurements from the UE, the RAN sends an RRC reconfiguration message, which configures a reconfiguration with synchronization (e.g., the RRC reconfiguration message includes ReconfigurationWithSync IE) for the change of serving cell (e.g., PCell or PSCell). When the UE operates with at least one secondary cell (SCell) and carrier aggregation (CA) with the PCell or PSCell, the RAN must release at least one SCell due to the change of the PCell or PSCell. Serving cell changes involve a complete L2 (and L1) reset, resulting in longer latency, greater overhead, and longer downtime. For these reasons, the 3rd Generation Partnership Project (3GPP) proposed developing new mobility technologies for serving cell changes. These technologies aim to reduce latency and overhead and are known as Lower Layer Triggered Mobility (LTM) or faster serving cell handover.

[0009] When a UE hands over from a serving cell to a target cell within the RAN, the UE must perform a random access procedure to synchronize with the target cell in the uplink, i.e., in the direction from the UE to the RAN. Only after the UE successfully completes the random access procedure can it begin communicating data with the RAN via the target cell. Therefore, a data communication interruption occurs during the serving cell handover. This interruption can be avoided if the UE can obtain a timing advance (TA) value for synchronization with the target cell before handover. However, it remains unclear how the UE and the RAN manage uplink synchronization with each other on the target cell before and after connecting to it. Summary of the Invention

[0010] An example embodiment of the technology disclosed herein is a method implemented in a user equipment (UE). The method includes starting or restarting a timing alignment timer for a target cell in response to obtaining a timing advance of a target cell from a radio access network (RAN) in a serving cell; receiving a command for initiating a lower-layer triggered mobility (LTM) cell change to the target cell; resetting a media access control (MAC) entity in response to the command; and maintaining the timing alignment timer running while resetting the MAC entity.

[0011] Another example embodiment of these technologies is a method implemented in a radio access network (RAN). The method includes providing a timing advance of a target cell to a user equipment (UE) in the serving cell; sending a command to the UE for initiating a lower-layer triggered mobility (LTM) cell change to the target cell; in response to the sending of the command, starting a timing alignment timer associated with the target cell; resetting a media access control (MAC) entity; and maintaining the timing alignment timer running while resetting the MAC entity.

[0012] Another example embodiment of these technologies is an apparatus that includes processing hardware and is configured to implement one of the methods described above. Attached Figure Description

[0013] FIG. 1A This is a block diagram of an example system in which the radio access network (RAN) and user equipment implement the techniques of this disclosure for managing uplink timing synchronization;

[0014] FIG. 1B Is FIG. 1A A block diagram of an example base station operating in the system, including centralized units (CU) and distributed units (DU);

[0015] FIG. 2A This is a block diagram of an example protocol stack. FIG. 1A The UE communicates with the base station according to this protocol stack;

[0016] FIG. 2B This is a block diagram of an example protocol stack. FIG. 1A The UE communicates with the CU and DU according to this protocol stack;

[0017] FIG. 3 An example scenario is shown where the UE performs a lower-level triggered mobility (LTM) cell change from one cell of the DU to another cell of the DU;

[0018] FIG. 4 Showing with FIG. 3 The scenario is roughly similar to the example scenario, except that the UE performs an inter-DU LTM cell change;

[0019] FIG. 5A Showing with FIG. 3 The scenario is roughly similar to the example scenario, except that the UE and the base station operate under dual connectivity (DC);

[0020] FIG. 5B Showing with FIG. 5A The example scenario is roughly similar, except that the secondary node (SN) sends an RRC reconfiguration message to the UE via the primary node (MN);

[0021] FIG. 6A Showing with FIG. 3 to FIG. 5B The scenario is roughly similar to the example scenario, except that the UE communicates with the MN and SN under the DC to perform inter-DU cell changes;

[0022] FIG. 6B Showing with FIG. 3 to FIG. 5B and FIG. 6A The scenario is roughly similar to the example scenario, except that the UE communicates under the DC, and the SN sends an RRC reconfiguration message to the UE via the MN;

[0023] FIG. 7A An example scenario is shown where the UE communicates with the M-DU and S-DU implemented in the same distributed base station under the DC, and receives LTM configuration via the S-DU;

[0024] FIG. 7B Showing with FIG. 7A Similar to the example scenario, the difference is that the UE receives the LTM configuration via the M-DU;

[0025] FIG. 8A An example scenario is shown where the UE communicates with the M-DU and S-DU implemented in the same distributed base station under the DC, and receives LTM configuration via the S-DU to communicate with the T-DU;

[0026] FIG. 8B Showing with FIG. 8A Similar to the example scenario, the difference is that the UE receives LTM configuration via M-DU to communicate with T-DU;

[0027] FIG. 9A This is a flowchart of an example method in the UE for managing uplink synchronization with the target cell using timing advance received in the LTM command;

[0028] FIG. 9B Is with FIG. 9A The flowchart of the example method is roughly similar to that of the method, except that after the UE accesses the target cell, it starts or restarts the time alignment timer used for uplink synchronization with the serving cell;

[0029] FIG. 9C Is with FIG. 9A The flowchart of the example method is roughly similar to that of the method, the difference being that the UE determines whether a random access procedure should be performed in the target cell based on whether the LTM command includes a TA value;

[0030] FIG. 10A This is a flowchart of an example method in the RAN for managing uplink synchronization with the UE using timing advance transmitted in LTM commands;

[0031] FIG. 10B Is with FIG. 10A The flowchart of the example method is roughly similar to that of the UE, except that after the UE accesses the target cell, the RAN starts or restarts the time alignment timer used for uplink synchronization with the serving cell.

[0032] FIG. 10C Is with FIG. 10A The flowchart of the example method is roughly similar to that of the method, the difference being that the RAN determines whether it should perform a random access procedure with the UE based on whether the LTM command includes a TA value;

[0033] FIG. 11A Is with FIG. 9A The flowchart of the example method is roughly similar to that of the method, except that the UE receives a random access response including the TA value from the RAN;

[0034] FIG. 11B Is with FIG. 11A The flowchart of the example method is roughly similar to that of the method, the difference being that the UE determines whether the LTM command instructs the UE to apply the TA value;

[0035] FIG. 12A This is a flowchart of an example method for managing uplink synchronization with the UE in the RAN, including sending a command to the UE to transmit a random access preamble in the target cell;

[0036] FIG. 12B This is a flowchart of an example method for managing uplink synchronization with the UE in the RAN, including determining whether to perform a random access procedure with the UE based on whether the LTM command instructs the UE to apply a TA value;

[0037] FIG. 13 It is in UE and FIG. 11A The flowchart of the example method is roughly similar to that of the method, but in which the UE also detects the expiration of the time alignment timer associated with the target cell, while the time alignment timer associated with the serving cell is still running;

[0038] FIG. 14A and FIG. 14B It is in UE and FIG. 11A The flowchart of the example method is roughly similar to that of the method, but in which the UE also detects the expiration of the time alignment timer associated with the serving cell, while the time alignment timer associated with the target cell is still running;

[0039] FIG. 15 It is in RAN and FIG. 12AThe flowchart of the example method is roughly similar to that of the method, but in which the RAN also detects the expiration of the time alignment timer associated with the target cell, while the time alignment timer associated with the serving cell is still running;

[0040] FIG. 16A and FIG. 16B It is in RAN and FIG. 12A The flowchart of the example method is roughly similar to that of the method, but in which the RAN also detects the expiration of the time alignment timer associated with the serving cell, while the time alignment timer associated with the target cell is still running;

[0041] FIG. 17A This is a flowchart of an example method for managing uplink synchronization in a UE, including determining which time alignment timer to start or restart based on the cell in which a random access response is received.

[0042] FIG. 17B This is a flowchart of an example method for managing uplink synchronization in a UE, including determining which time alignment timer to start or restart based on the cell in which the random access preamble is sent;

[0043] FIG. 17C This is a flowchart of an example method for managing uplink synchronization in a UE, including determining which time alignment timer to start or restart based on whether the transmitted random access preamble is used for early TA acquisition;

[0044] FIG. 17A This is a flowchart of an example method for managing uplink synchronization in a UE, including determining which time alignment timer to start or restart based on the cell in which a random access response is received.

[0045] FIG. 17B This is a flowchart of an example method for managing uplink synchronization in a UE, including determining which time alignment timer to start or restart based on the cell in which the random access preamble is sent;

[0046] FIG. 17C This is a flowchart of an example method for managing uplink synchronization in a UE, including determining which time alignment timer to start or restart based on whether the transmitted random access preamble is used for early TA acquisition;

[0047] FIG. 18A This is a flowchart of an example method for managing uplink synchronization in a RAN, including determining which time alignment timer to start or restart based on the cell in which a random access response is received.

[0048] FIG. 18BThis is a flowchart of an example method for managing uplink synchronization in a RAN, including determining which time alignment timer to start or restart based on the cell in which the random access preamble is sent; and

[0049] FIG. 18C This is a flowchart of an example method for managing uplink synchronization in the RAN, including determining which time alignment timer to start or restart based on whether the transmitted random access preamble is used for early TA acquisition. Detailed Implementation

[0050] FIG. 1A An example wireless communication system 100 is depicted in which user equipment (UE) and radio access network (RAN) can implement uplink timing synchronization technology; the wireless communication system 100 includes UE 102, base station (BS) 104, base station 106, and core network (CN) 110. UE 102 is initially connected to base station 104. In some scenarios, base station 104 can perform SN addition to configure UE 102 to operate in dual connectivity (DC) with base stations 104 and 106. Base stations 104 and 106 operate as MN and SN of UE 102, respectively.

[0051] In various configurations of the wireless communication system 100, base station 104 can be implemented as a primary eNB (MeNB) or primary gNB (MgNB), and base station 106 can be implemented as a secondary gNB (SgNB). UE 102 can communicate with base station 104 and base station 106 via the same RAT (such as EUTRA or NR) or different RATs. When base station 104 is a MeNB and base station 106 is an SgNB, UE 102 can be in EUTRA-NR DC (EN-DC) with both the MeNB and SgNB.

[0052] In some cases, the MeNB or SeNB is implemented as an ng-eNB instead of an eNB. When base station 104 is the primary ng-eNB (Mng-eNB) and base station 106 is the SgNB, UE 102 can be in a next-generation (NG) EUTRA-NRDC (NGEN-DC) with both the Mng-eNB and SgNB. When base station 104 is a MgNB and base station 106 is an SgNB, UE 102 can be in an NR-NR DC (NR-DC) with both the MgNB and SgNB. When base station 104 is a MgNB and base station 106 is a secondary ng-eNB (Sng-eNB), UE 102 can be in an NR-EUTRA DC (NE-DC) with both the MgNB and Sng-eNB.

[0053] In the scenario where UE 102 switches from base station 104 to base station 106, base stations 104 and 106 operate as the source base station (S-BS) and the target base station (T-BS), respectively. UE 102 can, for example, communicate with base station 104 and the auxiliary base station (T-BS) under DC before the handover. FIG. 1A (Not shown in the diagram) Operation. After the handover is completed, UE 102 can continue to operate with base station 106 and the additional base station under DC or with base station 106 under single connection (SC). In this case, base stations 104 and 106 operate as the source MN (S-MN) and the target MN (T-MN), respectively.

[0054] The core network (CN) 110 can be either the Evolved Packet Core (EPC) 111 or the fifth-generation core (5GC) 160; both are... FIG. 1A The following description is provided. Base station 104 may be an eNB supporting an S1 interface for communication with EPC 111, an ng-eNB supporting an NG interface for communication with 5GC 160, or a gNB supporting an NR radio interface and an NG interface for communication with 5GC 160. Base stations 104 and 106 may support X2 or Xn interfaces to directly exchange messages with each other during the scenarios discussed below. Among other components, EPC 111 may include a Serving Gateway (SGW) 112, a Mobility Management Entity (MME) 114, and a Packet Data Network Gateway (PGW) 116. SGW 112 is typically configured to deliver user plane packets related to audio calls, video calls, Internet services, etc., and MME 114 is configured to manage authentication, registration, paging, and other related functions. PGW 116 provides connectivity from the UE to one or more external packet data networks (e.g., Internet networks and / or Internet Protocol (IP) Multimedia Subsystem (IMS) networks). 5GC 160 includes User Plane Functions (UPF) 162, Access and Mobility Management (AMF) 164, and / or Session Management Functions (SMF) 166. UPF 162 is generally configured to transmit user plane packets related to audio calls, video calls, Internet services, etc., AMF 164 is configured to manage authentication, registration, paging, and other related functions, and SMF 166 is configured to manage PDU sessions.

[0055] like FIG. 1A As shown, base station 104 supports cell 124A, and base station 106 supports cell 126. Cells 124A and 126 can partially overlap, allowing UE 102 to communicate with base stations 104 and 106 under DC, where one of base stations 104 and 106 is MN and the other is SN. Base station 104 can support additional cells such as cells 124B and 124C, and base station 106 can support additional cells (…).FIG. 1A (Not shown in the diagram). Cells 124A, 124B, and 124C may partially overlap, allowing UE 102 to communicate with base station 104 via carrier aggregation (CA). Base station 104 may operate cells 124A, 124B, and 124C via one or more transmit and receive points (TRPs). More specifically, when UE 102 is in a DC configuration with base stations 104 and 106, one of base stations 104 and 106 operates as a MeNB, Mng-eNB, or MgNB, while the other operates as an SgNB or Sng-eNB.

[0056] Generally, the wireless communication network 100 may include any suitable number of base stations supporting NR cells and / or EUTRA cells. More specifically, the EPC 111 or 5GC 160 may connect to any suitable number of base stations supporting NR cells and / or EUTRA cells. Although the examples below specifically refer to particular CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general, the techniques disclosed herein can also be applied to other suitable radio access and / or core network technologies, such as sixth-generation (6G) radio access and / or 6G core networks or 5G NR-6G DC.

[0057] Continue to refer to FIG. 1A 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 storage of instructions executed by the one or more general-purpose processors. Additionally or alternatively, the processing hardware 130 may include dedicated processing units.

[0058] Processing hardware 130 may implement LTM controller 132 to support the LTM process and TA acquisition controller 134 to support early TA acquisition at the UE. For example, LTM controller 132 and TA acquisition controller 134 may be implemented as corresponding instruction sets executable by one or more processors. Processing hardware 130 may also implement additional components, such as a PHY controller (not shown), configured to transmit data and control signals with one or more user equipments (e.g., UE 102) via one or more cells (e.g., cells 124A, 124B, and / or 124C) and / or one or more TRPs on physical downlink (DL) channels and DL reference signals. The PHY controller may be configured to receive data and control signals with one or more user equipments via one or more cells (e.g., cells 124A, 124B, and / or 124C) and / or one or more TRPs on physical uplink (UL) channels and / or UL reference signals. Processing hardware 130 may also implement a MAC controller (not shown), configured to perform MAC functions with one or more user equipments. MAC functions include random access (RA) procedures, managing UL timing advances for one or more user equipments, and / or transmitting UL / DL MACPDUs with one or more user equipments. MAC functions include lower-layer triggered mobility (LTM) related functions as described below. Processing hardware 130 may further include an RRC controller (not shown) to implement procedures and messaging at the RRC sublayer of the protocol communication stack. For example, the RRC controller may be configured to support RRC messaging associated with handover procedures, and / or support necessary operations when base station 104 operates as MN relative to SN or as SN relative to MN. Base station 106 may include processing hardware 140 similar to processing hardware 130. Specifically, components 142, 144, and 146 may be similar to components 132 and 134, respectively.

[0059] UE 102 is equipped with processing hardware 150, which may include one or more general-purpose processors such as a CPU and a non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or dedicated processing units. Processing hardware 150 may implement an LTM controller 152 to support the LTM process, and a TA acquisition controller 154 to support early TA acquisition in the serving cell and / or target cell. For example, LTM controller 152 and TA acquisition controller 154 may be implemented as corresponding instruction sets executable by one or more processors.

[0060] The processing hardware 150 may also implement additional components, such as a PHY controller (not shown), configured to receive data and control signals with base station 104 or 106 via one or more cells (e.g., cells 124A, 124B, 124C, and / or 126) and / or one or more TRPs on the physical DL channel and / or DL ​​reference signal. The PHY controller may be configured to transmit data and control signals with base station 104 or 106 via one or more cells (e.g., cells 124A, 124B, 124C, and / or 126) and / or one or more TRPs on the physical UL channel and / or UL reference signal. In an example implementation, the processing hardware 150 includes a MAC controller (not shown) configured to perform MAC functions with base station 104 or 106. For example, MAC functions include random access procedures, managing UL timing advance for one or more user facilities, and communicating UL / DL MAC PDUs with base station 104 or 106. In another example, the MAC functions include LTM-related functions as described below. The processing hardware 150 may further include an RRC controller (not shown) to implement process and message passing at the RRC sublayer of the protocol communication stack.

[0061] In operation, UE 102 can use radio bearers (e.g., DRB or SRB) that terminate at MN 104 or SN 106 at different times under DC. When communicating on radio bearers in the uplink (UL) (from UE 102 to the base station) and / or downlink (from the base station to UE 102) directions, UE 102 can apply one or more security keys.

[0062] FIG. 1BExample distributed implementations of base stations such as base station 104 or 106 are depicted. In this implementation, the base station includes a centralized unit (CU) 172 and one or more distributed units (DUs) 174. In some implementations, CU 172 is equipped with processing hardware including one or more general-purpose processors such as a CPU and a non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or a dedicated processing unit. In some implementations, CU 172 is equipped with processing hardware 130. In a further implementation, CU 172 is equipped with processing hardware 140. The processing hardware 140 in the example implementation includes an SN RRC controller 142 configured to manage or control one or more RRC configurations and / or RRC procedures when base station 106 operates as an SN. In some implementations, DU 174 is also equipped with processing hardware including one or more general-purpose processors such as a CPU and a non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or a dedicated processing unit. In some implementations, the processing hardware includes: a Media Access Control (MAC) controller configured to manage or control one or more MAC operations or procedures (e.g., random access procedures); and a Radio Link Control (RLC) controller configured to manage or control one or more RLC operations or procedures when the base station 106 operates as an MN or SN. In some implementations, the processing hardware includes a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0063] FIG. 2A An example protocol stack 200 is shown in a simplified manner, according to which UE 102 communicates with an eNB / ng-eNB or gNB (e.g., one or more of base stations 104, 106).

[0064] In example stack 200, the EUTRA physical layer (PHY) 202A provides a transport channel to the EUTRA MAC sublayer 204A, which in turn provides a logical channel to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A then provides an RLC channel to the EUTRA PDCP sublayer 208 and, in some cases, to the NR PDCP sublayer 210. Similarly, the NRPHY 202B provides a transport channel to the NR MAC sublayer 204B, which in turn provides a logical channel to the NR RLC sublayer 206B. The NR RLC sublayer 206B then provides data transmission services to the NR PDCP sublayer 210. The NR PDCP sublayer 210 then provides data transmission services to the Serving Data Adaptation Protocol (SDAP) 212 or the Radio Resource Control (RRC) sublayer. FIG. 2A (Not shown in the image) provides data transmission services. In some implementations, UE 102 supports both EUTRA and NR stacks, such as... FIG. 2A As shown, this is to support handover between EUTRA and NR base stations and / or support DCs via EUTRA and NR interfaces. Further, as... FIG. 2A As shown, UE 102 supports layering of NR PDCP 210 over EUTRA RLC 206A, and layering of SDAP sublayer 212 over NR PDCP sublayer 210.

[0065] EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 receive packets referred to as Service Data Units (SDUs) (e.g., from Internet Protocol (IP) layers that are directly or indirectly layered on PDCP layers 208 or 210), and transmit packets referred to as Protocol Data Units (PDUs) (e.g., to RLC layers 206A or 206B). Except where the difference between SDU and PDU is relevant, for simplicity, this disclosure refers to both SDU and PDU as “packets”.

[0066] In some implementations, on the control plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 provide signaling radio bearer (SRB) or RRC sublayer ( FIG. 2A (Not shown in the diagram) to exchange, for example, RRC messages or Non-Access Stratum (NAS) messages. In some implementations, on the user plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 provide data radio bearers (DRBs) to support data exchange. In further implementations, the data exchanged on NR PDCP sublayer 210 is SDAP PDU, Internet Protocol (IP) packets, or Ethernet packets.

[0067] FIG. 2B An example protocol stack 250 for UE 102 to communicate with DU (e.g., DU 174) and CU (e.g., CU 172) is shown in a simplified manner. The radio protocol stack 200 is functionally broken down as follows: FIG. 2B The radio protocol stack 250 is shown in the diagram. In some implementations, the CU at either base station 104 or 106 retains all control and upper-layer functions (e.g., RRC 214, SDAP 212, NR PDCP 210), while lower-layer operations (e.g., NR RLC 206B, NR MAC 204B, and NR PHY 202B) are delegated to the DU. To support connectivity to the 5GC, NR PDCP 210 provides SRBs to RRC 214, and NR PDCP 210 provides DRBs to SDAP 212 and SRBs to RRC 214.

[0068] Next is one of them FIG. 1A The system includes several example scenarios where the base station operating in the system sends a configuration to the UE 102 and later activates the configuration for communication between the UE 102 and the base station. Generally, FIG. 3 to FIG. 8B Similar events are labeled with similar reference numbers (e.g., event 394 is similar to...). FIG. 4 Event 494 FIG. 5A Event 594 FIG. 6A Event 694 FIG. 7A Event 794 in Figure 8 and Event 894 in Figure 8, the differences of which will be discussed below where appropriate. Apart from the differences shown in the figures and discussed below, any of the alternative implementations discussed for specific events (e.g., those used for messaging and processing) can be applied to other events in the figures that are labeled with similar reference numerals.

[0069] First refer to FIG. 3 In scenario 300, base station 104 includes CU 172 and DU 174, and DU 174 operates cell 124A. UE 102 initially uses the serving DU to communicate with DU 174 on cell 124A 302, and, for example, uses the serving CU to communicate with CU 172 via DU 174. In other words, DU 174 is the serving DU that is communicating with UE 102. In some implementations, UE 102 uses the serving DU in carrier aggregation (CA) configuration on cell 124A and other cells (e.g., FIG. 1AUE 102 communicates with DU 174 on cell 124A (not shown). DU 174 operates other cells. In other implementations, UE 102 communicates with DU 174 only on cell 124A. In some implementations, UE 102 communicates with DU 174 on cell 124A and / or other cells via one or more Transmit Receive Points (TRPs). In some implementations, cell 124A is a PCell. In such cases, other cells include SCells and / or additional cells associated with a PCell or SCell. In other implementations, cell 124A is an SCell, and one of the other cells is a PCell. In such cases, the remaining cells include SCells and / or additional cells associated with a PCell or SCell. In the following description, base station 104 is DU 174, CU 172, or DU 174 and CU 172.

[0070] In some implementations, UE 102 transmits a 302 UL PDU and / or UL control signal to base station 104 via one or more TRPs in cell 124A and / or other cells. In some implementations, UE 102 communicates UL PDUs and / or DL ​​PDUs with base station 104 via a radio bearer, which includes an SRB and / or DRB. In some implementations, base station 104 configures a radio bearer for UE 102. In some implementations, the UL control signal includes UL control information, channel state information, Hybrid Automatic Repeat Request (HARQ) acknowledgment (ACK), HARQ negative ACK, scheduling request, and / or probe reference signal. In a further implementation, UE 102 receives DL PDUs and / or DL ​​control signals from base station 104 via one or more TRPs in cell 124A and / or other cells. In some implementations, the DL control signal includes DL control information (DCI) and reference signals (e.g., synchronization signal block, channel state information reference signal (CSI-RS), and / or tracking reference signal). In some implementations, base station 104 transmits DCI on the physical downlink control channel (PDCCH) monitored by UE 102 in cell 124A and / or other cells via one or more TRPs.

[0071] In some implementations, the serving DU configuration includes physical layer configuration parameters, MAC configuration parameters, and / or RLC configuration parameters. In some implementations, DU 174 sends these configuration parameters to CU 172. CU 172 generates one or more messages (e.g., an RRC reconfiguration message) including the configuration parameters and sends these messages to UE 102 via DU 174. In a further implementation, DU 174 sends the configuration parameters directly to UE 102. In some implementations, the serving DU configuration is a CellGroupConfig IE (e.g., as defined in 3GPP TS 38.331). In a further implementation, the serving DU configuration includes configuration parameters in a CellGroupConfig IE. In yet another further implementation, the serving CU configuration includes PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters. In some implementations, the serving CU configuration includes a MeasConfig IE and / or a RadioBearerConfig IE (e.g., as defined in 3GPP TS 38.331), or configuration parameters within the MeasConfig IE and / or RadioBearerConfig IE. In some implementations, the serving DU configuration includes a CSI-MeasConfig IE or configuration parameters for Channel State Information (CSI) measurement and reporting. In a further implementation, the serving CU configuration includes a CSI-MeasConfig IE or configuration parameters for CSI measurement and reporting. In some implementations, UE 102 receives the serving CU configuration or configuration parameters within the serving CU configuration from CU 172 via DU 174. In a further implementation, UE 102 receives a portion of the serving CU configuration and / or a portion of the serving DU configuration from a base station other than base station 104, and receives the remainder of these configuration parameters from base station 104.

[0072] When communicating with base station 104, UE 102 sends at least one measurement report (304) to DU 174. In some implementations, the at least one measurement report includes a Layer 1 (L1) measurement report and / or a Layer 3 (L3) measurement report for at least one serving cell and / or at least one non-serving cell of UE 102. For each of the L3 measurement reports, DU 174 sends a DU-to-CU message (306) including the L3 measurement report to CU 172. In some implementations, the DU-to-CU message of event 306 is an F1 Application Protocol (F1AP) message (e.g., a UL RRC message delivery message). In some implementations, DU 174 does not send or avoids sending L1 measurement reports to CU 172. At least one serving cell includes cell 124A and / or other cells, and at least one non-serving cell includes cell 124B and / or cell 124C. In some implementations, the serving DU configuration or serving CU configuration includes at least one measurement configuration. In some implementations, in event 302, UE 102 receives one or more RRC messages (e.g., RRCReconfiguration messages) from CU 172 via DU 174, including at least one measurement configuration. Based on the at least one measurement configuration, UE 102 performs a measurement and sends at least one measurement report (304) to DU 174. In some implementations, the at least one measurement configuration includes an L3 measurement configuration (e.g., MeasConfig IE) and / or an L1 measurement configuration. In some implementations, the L1 measurement configuration (e.g., CSI-MeasConfig IE) includes an L1 measurement resource configuration and / or an L1 measurement report configuration. In some implementations, the L1 measurement resource configuration configures reference signals and / or resources of reference signals for UE 102 to measure and obtain L1 measurement results. In some implementations, the reference signals include CSI-RS and / or Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) Resource Block (SSB). For example, the L1 measurement resource configuration is CSI-ResourceConfig IE. In some implementations, the L1 measurement report configuration configures UE 102 to send L1 measurement results / reports. For example, the L1 measurement report configuration is CSI-ReportConfig IE. For instance, UE 102 sends an L3 measurement report to CU 172 via DU 174 according to the L3 measurement configuration. UE 102 sends an L1 measurement report to DU 174 according to either the L1 measurement configuration or the L1 measurement report configuration. In some implementations, DU 174 does not send L1 measurement reports to CU 172.

[0073] In some implementations, the L1 measurement configuration is a specially defined RRCIE (e.g., as defined in 3GPP TS 38.331) for lower-layer triggered mobility (LTM). In some implementations, the L1 measurement resource configuration is a specially defined RRCIE (e.g., as defined in 3GPP TS 38.331) for LTM. In some implementations, the L1 measurement resource configuration is a specially defined RRCIE (e.g., as defined in 3GPP TS 38.331) for LTM. In some implementations, each of the L1 measurement report configurations includes a trigger event configuration that configures a trigger event to trigger UE 102 to send an L1 measurement report. If UE 102 detects the trigger event, UE 102 sends an L1 measurement report to DU 174.

[0074] In some implementations, each of the L1 measurement reports includes at least one L1 measurement result. In some implementations, the at least one L1 measurement result includes at least one L1 reference signal received power (L1-RSRP) value and / or at least one L1 signal-to-interference-noise ratio (L1-SINR) value. In some implementations, for each of the L1 measurement reports, UE 102 transmits a PUCCH transmission including the L1 measurement report to DU 174. That is, UE 102 transmits each of the L1 measurement reports to DU 174 on the PUCCH. In a further implementation, for each of the L1 measurement reports, UE 102 transmits a PUSCH transmission including the L1 measurement report to DU 174. That is, UE 102 transmits each of the L1 measurement reports to DU 174 on the PUSCH. In yet another further implementation, UE 102 transmits a portion of the L1 measurement report on the PUCCH and the remainder of the L1 measurement report to DU 174 on a physical UL shared channel (e.g., PUSCH). In other words, for each portion of the L1 measurement report, UE 102 sends a PUCCH transmission including the L1 measurement report to DU 174, and for each remaining portion of the L1 measurement report, UE 102 sends a PUSCH transmission including the L1 measurement report to DU 174. In some implementations, each portion of the L1 measurement report is a part of the CSI (i.e., a CSI component) or the entire CSI. In some implementations, UE 102 includes other CSI components in each of the aforementioned PUCCH and / or PUSCH transmissions. In some implementations, these other CSI components include the Channel Quality Indicator (CQI), Precoding Matrix Indicator (PMI), CSI-RS Resource Indicator (CRI), SSB Resource Indicator (SSBRI), Layer Indicator (LI), and / or Rank Indicator (RI). In some implementations, UE 102 does not send the L1 measurement report to DU 174 in the format of an RRC message.

[0075] In some implementations, each of the L3 measurement reports includes at least one L3 measurement result. In further implementations, at least one L3 measurement result includes at least one RSRP (e.g., a value) and / or at least one SINR (e.g., a value). In some implementations, UE 102 transmits each of the L3 measurement reports to CU 172 via DU 174 on the PUSCH. In some implementations, each of the L3 measurement reports includes an RRC message (e.g., a MeasurementReport message). In further implementations, each of the L3 measurement configurations includes a specific measurement identifier (e.g., a measId), and each of the L3 measurement reports includes a specific measurement identifier in a specific L3 measurement configuration. In some implementations, when CU 172 receives an L3 measurement report including a measurement identifier and an L3 measurement result from UE 102 via DU 174, CU 172 determines that the L3 measurement report is associated with the L3 measurement configuration identified by the measurement identifier.

[0076] In some implementations, for each of at least one measurement report (e.g., an L1 measurement report), UE 102 sends 304 to DU 174, which includes a MAC control element (CE) of the measurement report. In order to send 304 to DU 174, UE 102 generates one or more MAC PDUs, each MAC PDU including one or more MAC CEs.

[0077] In some implementations, UE 102 performs measurements on one or more reference signals according to at least one measurement configuration. In some implementations, the one or more reference signals include one or more Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) Resource Blocks (SSBs) and / or one or more CSI-RSs. UE 102 obtains at least one L1 measurement result and / or at least one L3 measurement result from the measurements. DU 174 in cell 124A and other cells (e.g., cell 124B, cell 124C and / or FIG. 1A One or more reference signals are transmitted on a cell (not shown in the diagram).

[0078] Upon receiving one or more of at least one measurement report from UE 102 (e.g., in response to this), base station 104 (i.e., CU 172 or DU 174) determines a first cell (e.g., cell 124B) for UE 102 to use for LTM. In some implementations, base station 104 determines to prepare the first cell for UE 102 because at least one measurement report indicates that the first cell uses base station 104 to communicate with UE 102. In some implementations, base station 104 determines to prepare the first cell for UE 102 because at least one measurement report indicates that the first cell is eligible as a candidate cell for communicating with UE 102. In some implementations, CU 172 determines to prepare the first cell for UE 102 if an L3 measurement report indicates that the signal strength and / or quality of the first cell is higher than a first predetermined threshold, better than the strength and / or quality of cell 124A, and / or better than the strength and / or quality of cell 124A by a first predetermined threshold. In a further implementation, if the L1 measurement report indicates that the signal strength and / or quality of the first cell is higher than a first predetermined threshold, better than the signal strength and / or quality of cell 124A, and / or better than the signal strength and / or quality of cell 124A by a first predetermined threshold, then DU 174 determines to prepare the first cell for UE 102. Alternatively, base station 104 determines to prepare the first cell for UE 102 regardless of whether a measurement report is received from UE 102.

[0079] When CU 172 determines that a first cell is ready for LTM, CU 172 sends a 308 First CU to DU message to DU 174 to prepare the first cell for UE 102. In some implementations, CU 172 includes the cell identifier (ID) 1 of the first cell in the First CU to DU message to request DU 174 to prepare the first cell for LTM for UE 102. For example, cell ID 1 is the Cell Global Identifier (CGI). In another example, the cell ID is part of the CGI. In yet another example, the cell ID is the Physical Cell ID (PCI). In response to the First CU to DU message, DU 174 generates a first LTM DU configuration for UE 102 (e.g., referred to herein as LTM DU configuration 1), which configures the first cell for LTM. DU 174 then sends a 310 First DU to CU message including LTM DU configuration 1 to CU 172 in response to the First CU to DU message. In some implementations, DU 174 includes cell ID 1 and LTM DU configuration 1 together in the IE of the first DU to CU message to indicate that LTM DU configuration 1 is associated with the first cell (i.e., cell ID 1). Instead of responding to a CU to DU message received from CU 172, DU 174 initiates the sending of the first DU to CU message to CU 172 when it determines that the first cell is ready.

[0080] In some implementations, DU 174 includes the cell ID of the first cell associated with LTM DU configuration 1 in the first DU to CU message to indicate that LTM DU configuration 1 is configured for or associated with the first cell. CU 172 identifies that LTM DU configuration 1 is configured for or associated with the first cell. In some implementations, CU 172 includes additional cell IDs (e.g., cell ID 2, ..., N) in the first CU to DU message to prepare additional cells (e.g., cells 2, ..., N) for LTM for UE 102, and DU 174 includes additional LTM DU configurations (e.g., LTM DU configuration 2, ..., N) for the additional cells, as described below. In such cases, DU 174 includes an indication in the first DU to CU message of which LTM DU configuration is associated with which cell (ID). Cells 1 and / or 2, ..., N are candidate cells.

[0081] In some implementations, CU 172 does not include the LTM DU configuration (e.g., a reference configuration) in the first CU-DU message. In such cases, DU 174 generates a reference LTM DU configuration, generates LTM DU configurations 1 and / or 2, ..., N (i.e., non-reference LTM DU configurations) based on the reference LTM DU configuration, and includes the reference LTM DU configuration in the first DU-CU message. In a further implementation, CU 172 includes the reference LTM DU configuration in the first CU-DU message. In such cases, DU 174 generates LTM DU configurations 1 and / or 2, ..., N, which are incremental configurations used to enhance the reference LTM DU configuration. In yet another further implementation, CU 172 includes the reference LTM DU configuration (e.g., a first reference LTM DU configuration) in the first CU-DU message. In such cases, DU 174 generates a reference LTM DU configuration (e.g., a second reference LTM DU configuration) that replaces the first reference LTM DU configuration, generates LTM DU configuration 1 and / or 2, ..., N based on the second reference LTM DU configuration, and includes the second reference LTM DU configuration in the first DU to CU message.

[0082] In some implementations, the reference LTM DU configuration includes physical layer configuration parameters, MAC configuration parameters, and / or RLC configuration parameters. In some implementations, the reference LTM DU configuration is a CellGroupConfig IE (e.g., as defined in 3GPPTS 38.331). In further implementations, the reference LTM DU configuration includes configuration parameters in a CellGroupConfig IE. In still further implementations, the reference LTM DU configuration includes a CSI-MeasConfig IE or configuration parameters for CSI measurement and reporting.

[0083] In some implementations, the reference LTM DU configuration differs from the service DU configuration. In a further implementation, a portion of the reference LTM DU configuration is identical to a portion of the service DU configuration, and the remainder of the reference LTM DU configuration differs from the remainder of the service DU configuration. In yet another further implementation, the reference LTM DU configuration is identical to the service DU configuration.

[0084] After receiving the first DU to CU message, CU 172 generates an RRC reconfiguration message (e.g., an RRCReconfiguration message) including LTM DU configuration 1, and sends a second CU to DU message 316 containing the RRC reconfiguration message to DU 174. In some implementations, CU 172 sends 316 in the RRC reconfiguration message, referencing the LTM DU configuration. In a further implementation, CU 172 sends 316 in the RRC reconfiguration message without carrying the reference LTM DU configuration. In some implementations, if CU 172 sends 302 in the RRC reconfiguration message, referencing the LTM DU configuration, to UE 102, then CU 172 sends 316 in the RRC reconfiguration message without carrying the reference LTM DU configuration. In a further implementation, if CU 172 receives a reference LTM DU configuration from DU 174, then CU 172 sends 316 in the RRC reconfiguration message, referring to the LTM DU configuration. Otherwise, if CU 172 does not receive the reference LTM DU configuration from DU 174, CU 172 will send 316 in the RRC reconfiguration message without carrying the reference LTM DU configuration.

[0085] In some implementations, CU 172 sends LTM DU Configuration 1 and / or LTM CU Configuration 1 (316 and 318) in a first container (e.g., field / IE) and includes the first container (e.g., LTM Configuration 1) in the RRC reconfiguration message. In this case, CU 172 generates the first container. The first container indicates to UE 102 not to immediately apply LTM DU Configuration 1 and / or LTM CU Configuration 1. In some implementations, UE 102 receives an RRC reconfiguration message (318) that includes the configuration (e.g., LTM DU Configuration 1). If the configuration is included in the first container, UE 102 avoids immediately applying the configuration. Otherwise, if the configuration is not included in the first container, UE 102 applies the configuration immediately. In some implementations, the first container includes or is a first add or modify list (e.g., ltm-ConfigToAddModList field, ltm-CandidateToAddModList field, or ltm-CandidateConfigToAddModList field). CU 172 includes LTMDU configuration 1 and / or LTM CU configuration 1 in the first element (e.g., referred to hereinafter as element 1) of the first add or modify list. In some implementations, CU 172 generates an RRC message (e.g., an RRCReconfiguration message) that includes LTM DU configuration 1 and / or LTM CU configuration 1 and includes the RRC message in element 1. In some implementations, element 1 is an add or modify IE (e.g., LTM-ConfigToAddMod IE, LTM-Candidate IE, LTM-CandidateToAddMod IE, or LTM-Candidate ConfigToAddMod IE). In some implementations, when UE 102 receives the first add or modify list, UE 102 stores the first add or modify list (e.g., in a variable in its random access memory (RAM)). In a further implementation, DU 174 generates a first container and includes the first container in the first DU to CU message. In a further implementation, DU 174 generates element 1 and includes element 1 in the first DU to CU message.

[0086] In some implementations, CU 172 sends 316 LTM CU configuration 1 in the RRC reconfiguration message and the first container or element 1, where LTM CU configuration 1 is associated with LTM DU configuration 1. In some implementations, to associate LTM CU configuration 1 with LTM DU configuration 1, CU 172 includes LTM CU configuration 1 and LTM DU configuration 1 in element 1. In some implementations, CU 172 sends 316 LTM CU configuration 2, ..., N in the RRC reconfiguration message or the second container, where LTM CU configuration 2, ..., N is associated with LTM DU configuration 2, ..., N, respectively. In a further implementation, to associate LTM CU configuration 2, ..., N with LTM DU configuration 2, ..., N, CU 172 includes LTM CU configuration 2, ..., N and LTM DU configuration 2, ..., N, respectively in elements 2, ..., N. In a further implementation, CU 172 includes the LTM CU configurations 2, ..., N associated with LTM DU configurations 2, ..., N in elements 2, ..., N. In a further implementation, CU 172 sends 316 in the RRC reconfiguration message without carrying some or all of the LTM CU configurations for LTM DU configuration 1 and / or LTM DU configurations 2, ..., N.

[0087] Upon receiving the 316 RRC reconfiguration message, DU 174 sends the 318 RRC reconfiguration message to UE 102. In response, UE 102 sends the 320 RRC reconfiguration complete message (e.g., RRCReconfigurationComplete message) to DU 174, and DU 174 then sends a second DU-to-CU message, 322, including the RRC reconfiguration complete message, to CU 172. In some implementations, CU 172 performs security protection on the RRC reconfiguration message (e.g., integrity protection and / or encryption). For example, CU 172 generates an integrity-based message authentication code (MAC-I) for the RRC reconfiguration message, encrypts the RRC reconfiguration message and the MAC-I to obtain an encrypted RRC reconfiguration message and an encrypted MAC-I, and sends PDCP PDUs 316 and 318, including the encrypted RRC reconfiguration message and the encrypted MAC-I, to UE 102 via DU 174. When UE 102 receives PDCP PDUs 316 and 318 from CU 172 via DU 174, UE 102 decrypts the encrypted RRC reconfiguration and encrypted MAC-I to obtain the RRC reconfiguration message and MAC-I, and verifies the validity of the MAC-I. If UE 102 verifies that the MAC-I is invalid, UE 102 discards or ignores the RRC reconfiguration message. In some implementations, UE 102 performs an RRC connection reconstruction procedure in response to an invalid MAC-I. In some implementations, if UE 102 verifies that the MAC-I is valid, UE 102 processes the RRC reconfiguration. UE 102 avoids applying (i.e., executing) LTM DU configuration 1 until it receives LTM commands 330 and 350 to activate LTM DU configuration 1.

[0088] Events 308 (optional) and 310 in FIG. 3 This is collectively referred to as LTM preparation process 390. Events 316, 318, 320, and 322 are... FIG. 3 This is collectively referred to as the LTM configuration delivery process 394.

[0089] In some implementations, the first CU to DU message is a UE ContextModification Request message, and the first DU to CU message is a UE ContextModification Response message or a UE Context Modification Required message. In some implementations, CU 172 sends a UE Context Modification Confirmation message to DU 174 in response to the UE Context Modification Required message. In some implementations, the second CU to DU message is a DL RRC Message Transfer message. In a further implementation, the second CU to DU message is a UE Context Modification Request message, and DU 174 sends a second DU to CU message (e.g., a UE Context Modification Response message) to CU 172 in response to the second CU to DU message.

[0090] In some implementations, CU 172 includes the reference LTM CU configuration 316 in the RRC reconfiguration message or the first container. In some implementations, CU 172 generates LTM CU configuration 1 (i.e., a non-reference LTM CU configuration) as an incremental configuration to enhance the reference LTM CU configuration. In some implementations, CU 172 generates some or all of LTM CU configurations 2, ..., N as incremental configurations to enhance the reference LTM CU configuration. In some implementations, CU 172 sends the reference LTM CU configuration 316 in the RRC reconfiguration message or the first container, excluding the non-reference LTM CU configuration. In a further implementation, CU 172 sends 316 carrying the reference LTM CU configuration and / or the reference LTM DU configuration in an additional container (e.g., a reference LTM configuration) of the RRC reconfiguration message.

[0091] In some implementations, the reference LTM CU configuration differs from the service CU configuration. In some implementations, a portion of the reference LTM CU configuration is identical to a portion of the service CU configuration, and the remainder of the reference LTM CU configuration differs from the remainder of the service CU configuration. In a further implementation, the reference LTM CU configuration is identical to the service LTM CU configuration.

[0092] In some implementations, CU 172 includes the first LTM ID (hereinafter referred to as ID 1) used to identify LTM DU configuration 1 or element 1 in the RRC reconfiguration message. In some implementations, CU 172 includes ID 1 in the first container or element 1. In some implementations, CU 172 assigns ID 1.

[0093] In some implementations, CU 172 sends ID 1 to DU 174, and DU 174 associates ID 1 with LTM DU configuration 1 and / or cell ID 1. In some implementations, CU 172 includes ID 1 in the first CU-DU message. In some implementations, after receiving the first DU-CU message, CU 172 sends a third CU-DU message including ID 1 to DU 174, instead of including ID 1 in the first CU-DU message. In some implementations, in the third CU-DU message, CU 172 includes LTM DU configuration 1 and ID 1, and indicates the association between ID 1 and LTM DU configuration 1. Therefore, DU 174 directly associates ID 1 with LTM DU configuration 1. In a further implementation, in the third CU-DU message, CU 172 includes cell ID 1 and ID 1 (i.e., the first LTM ID), and indicates the association between cell ID 1 and ID 1. Therefore, DU 174 associates ID 1 with LTM DU configuration 1 based on the association between cell ID 1 and ID 1, and the association between cell ID 1 and LTM DU configuration 1. In a further implementation, in the third CU to DU message, CU 172 includes LTM DU configuration 1, cell ID 1, and ID 1, and indicates the association between ID 1, LTM DU configuration 1, and / or cell ID 1. In some implementations, DU 174 sends a third DU to CU 172 in response to the third CU to DU message. In some implementations, the third CU to DU message and the third DU to CU message are a UE context modification request message and a UE context modification response message. Events 312 (optional) and 314 (optional) in FIG. 3 This is collectively referred to as LTM ID allocation procedure 392. In some implementations, CU 172 includes ID 1, cell ID 1, and / or LTM DU configuration 1 in the second CU to DU message, as described above. Therefore, the third CU to DU message is omitted.

[0094] In some implementations, CU 172 includes ID 1 in the first CU to DU message, and DU 174 includes ID 1 in LTM DU configuration 1, the first container, or element 1. Alternatively, DU 174 does not include ID 1 in LTM DU configuration 1, the first container, and / or element 1.

[0095] In some implementations, CU 172 includes the referenced LTM DU configuration in a first container. For example, CU 172 includes the referenced LTM DU configuration in a field of a first container that is different from the field of the first container that includes LTM DU configuration 1. In some implementations, CU 172 includes the referenced LTM DU configuration 316 in an RRC reconfiguration message outside the first container. For example, CU 172 generates a third container (e.g., field / IE) to include the first container and the referenced LTM DU configuration, and includes the third container 316 in the RRC reconfiguration message. In a further implementation, DU 174 includes the referenced LTM DU configuration in a first container. For example, DU 174 includes the referenced LTM DU configuration in a field of a first container that is different from the field of the first container that includes LTM DU configuration 1. In yet another further implementation, DU 174 generates a fourth container (e.g., field / IE) to include the first container and the referenced LTM DU configuration, and includes the fourth container 310 in the first DU to CU message. In this case, CU 172 includes the fourth container 316 in the RRC reconfiguration message. Alternatively, CU 172 retrieves the reference LTM DU configuration and LTM DU configuration 1 from the fourth container, and includes the reference LTM DU configuration and LTM DU configuration 1, as described above.

[0096] In some implementations, neither CU 172 nor DU 174 is assigned an ID to identify the reference LTM DU configuration.

[0097] In some implementations, LTM DU configuration 1 includes multiple configuration parameters for UE 102 to communicate with DU 174 on the first cell. In some implementations, these multiple configuration parameters include physical layer configuration parameters (e.g., PhysicalCellGroupConfig IE), MAC layer configuration parameters (e.g., MAC-CellGroupConfig IE), and / or RLC configuration parameters (e.g., RLC-BearerConfig IE). In further implementations, these multiple configuration parameters include specific cell configurations (e.g., SpCellConfig IE) and / or one or more SCell configurations (e.g., SCellConfig IE). In some implementations, LTM DU configuration 1 is a CellGroupConfig IE (e.g., as defined in 3GPP TS 38.331). In other implementations, LTM DU configuration 1 includes configuration parameters within a CellGroupConfig IE.

[0098] In some implementations, LTM CU configuration 1 includes PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters. In some implementations, LTM CU configuration 1 includes MeasConfig IE and / or RadioBearerConfig IE (e.g., as defined in 3GPP TS 38.331), or includes configuration parameters within MeasConfig IE and / or RadioBearerConfig IE. In some implementations, LTM DU configuration 1 includes L1 measurement configuration 1 (e.g., CSI-MeasConfig IE) and / or at least one Configuration Indicator (TCI) status configuration. In further implementations, LTM CU configuration 1 includes L1 measurement configuration and / or TCI status configuration 1. In some implementations, the L1 measurement configuration includes at least one Reference Signal (RS) resource configuration 1 and / or at least one Reporting configuration 1. In some implementations, RS resource configuration 1 configures one or more RSs or one or more RS resources associated with cell 1. RSs include SSBs and / or CSI-RSs. RS resources include SSB resources and / or CSI-RS resources. In some implementations, each RS resource configuration 1 includes an RS resource configuration ID. In some implementations, RS resource configuration 1 is (similar to) a CSI-ResourceConfig IE. In some implementations, report configuration 1 configures one or more UL resources (e.g., PUCCH or PUSCH resources) for UE 102 on cell 1 to transmit measurement results. In some implementations, each report configuration 1 includes one or more RS resource configuration IDs identifying one or more RS resource configurations included in RS resource configuration 1. In some implementations, each TCI state configuration 1 configures a TCI state that associates one or two DL RSs with corresponding Quasi-Co-location (QCL) types. DL RSs are associated with cell 1.

[0099] In some implementations, DU 174 includes L1 measurement configuration 1 and / or TCI state configuration 1 in the service DU configuration 1 (e.g., a non-LTM DU configuration). In some implementations, DU 174 includes the service DU configuration in the first DU-to-CU message. In other implementations, DU 174 sends an additional DU-to-CU message including the service DU configuration to CU 172. In some implementations, this additional DU-to-CU message is a UE context modification request message. In some implementations, CU 172 sends service DU configuration 1 (316 and 318) in an RRC reconfiguration message. In other implementations, CU 172 sends another RRC reconfiguration message including the service DU configuration to UE 102 via DU 174.

[0100] In some implementations, DU 174 includes the random access configuration in LTM DU configuration 1. In other implementations, DU 174 does not include the random access configuration in LTM DU configuration 1. In some implementations, if cell 124A and the first cell are not synchronized, DU 174 determines to include the random access configuration in LTM DU configuration 1. Otherwise, if cell 124A and the first cell are synchronized, DU 174 determines not to include the random access configuration in LTM DU configuration 1. In some implementations, if DU 174 determines that UE 102 has not yet synchronized with the first cell in UL, DU 174 determines to include the random access configuration in LTM DU configuration 1. Otherwise, if DU 174 determines that UE 102 is already synchronized with the first cell in UL, DU 174 determines not to include the random access configuration in LTM DU configuration 1. If LTM DU configuration 1 includes the random access configuration, UE 102 performs the 332 random access procedure according to the random access configuration, as described below. Otherwise, if LTM DU configuration 1 does not include a random access configuration or instructs UE 102 to skip the random access procedure in LTM, UE 102 skips or avoids performing the random access procedure in response to LTM DU configuration 1 excluding the random access configuration.

[0101] In some implementations, DU 174 includes random access configuration parameters in LTM DU configuration 1 and / or reference LTM DU configuration, regardless of whether cell 124A and the first cell are synchronized. UE 102 performs the 332 random access procedure based on the random access configuration parameters, as described below. In some implementations, the random access configuration parameters configure physical random access channel (PRACH) resources, the association between SSB and PRACH resources, and / or one or more PRACH occasions.

[0102] In some implementations, if cell 124A and the first cell are synchronized, DU 174 determines to include a first indication in LTM DU configuration 1, which configures UE 102 not to perform a random access procedure on the first cell. Otherwise, if cell 124A and the first cell are not synchronized, DU 174 determines not to include the first indication in LTM DU configuration 1. In a further implementation, if DU 174 determines that UE 102 is already synchronized with the first cell in the UL, DU 174 determines to include the first indication in LTM DU configuration 1. Otherwise, if DU 174 determines that UE 102 is not yet synchronized with the first cell in the UL, DU 174 determines not to include the first indication in LTM DU configuration 1. If LTM DU configuration 1 includes the first indication, UE 102 skips or avoids performing the random access procedure 332 according to or in response to the first indication. Otherwise, if LTM DU configuration 1 does not include the first indication, then in response to LTM DU configuration 1 excluding the first indication, UE 102 performs the 332 random access procedure according to the random access configuration, as described below.

[0103] In some implementations, DU 174 includes reconfigurations with synchronized configurations (e.g., ReconfigurationWithSync IE) in LTM DU configuration 1 or a special cell configuration. In further implementations, DU 174 does not include reconfigurations with synchronized configurations (e.g., ReconfigurationWithSync IE) in LTM DU configuration 1 or a special cell configuration. In some implementations, if cell 124A and the first cell are not synchronized, DU 174 determines to include reconfigurations with synchronized configurations in LTM DU configuration 1. Otherwise, if cell 124A and the first cell are synchronized, DU 174 determines not to include reconfigurations with synchronized configurations in LTM DU configuration 1. In yet another further implementation, if DU 174 determines that UE 102 has not yet synchronized with the first cell in the UL, DU 174 determines to include reconfigurations with synchronized configurations in LTM DU configuration 1. Otherwise, if DU 174 determines that UE 102 is already synchronized with the first cell in the UL, then DU 174 determines not to include the reconfiguration with the synchronization configuration in LTM DU configuration 1. In some implementations, if LTM DU configuration 1 includes the reconfiguration with the synchronization configuration, then UE 102 performs the 332 random access procedure in response to or based on the reconfiguration with the synchronization configuration, as described below. Otherwise, if LTM DU configuration 1 does not include the reconfiguration with the synchronization configuration, then UE 102 skips or avoids performing the 332 random access procedure. In some implementations, DU 174 includes the cell ID (i.e., cell ID 1) of cell 1 (i.e., the first cell) in LTM DU configuration 1. In some implementations, cell ID 1 is PCI. In a further implementation, cell ID 1 is CGI. In some implementations, cell ID 1 included in LTM DU configuration 1 is PCI, while cell ID 1 included in the first CU to DU message is CGI. In a further implementation, LTM DU configuration 1 includes cell index 1, which is indexed to cell ID 1 or the first cell. Cell index 1 is not the cell ID. The cell index occupies fewer bits than the cell ID. In some implementations, CU 172 sets cell index 1 to a value and includes cell index 1 in the first CU to DU message.

[0104] In some implementations, upon receiving 304 to one or more of at least one measurement report (e.g., in response to this), base station 104 (i.e., CU 172 or DU 174) determines an additional cell (i.e., cell 2, ..., N) for LTM for UE 102. In some implementations, base station 104 determines the additional cell for LTM for UE 102 because at least one measurement report indicates that the additional cell can be used by base station 104 to communicate with UE 102. In some implementations, the additional cell includes cell 124C and / or cells other than cells 124A, 124B, and 124C. In some implementations, CU 172 determines that particular cell for LTM for UE 102 if an L3 measurement report indicates that the signal strength and / or quality of a particular cell in the additional cells is higher than a corresponding predetermined threshold and / or better than cell 124A. In some implementations, if an L1 measurement report indicates that the signal strength and / or quality of a particular cell in the additional cells is higher than a first predetermined threshold and / or better than cell 124A, then DU 174 determines that particular cell to be prepared for LTM by UE 102. In some implementations, the corresponding predetermined threshold for the additional cell is different from the first predetermined threshold. In some implementations, the corresponding predetermined threshold for the additional cell is the same as the first predetermined threshold. In further implementations, the corresponding predetermined threshold for the additional cell is the same or different. Alternatively, base station 104 determines to prepare the additional cell for UE 102 regardless of whether a measurement report is received from UE 102.

[0105] In some implementations, CU 172 determines the additional cell to be prepared, and CU 172 initiates and performs at least one additional LTM preparation procedure with DU 174 to prepare the additional cell for LTM, wherein each of the LTM preparation procedures is similar to procedure 390. In some implementations, DU 174 determines the additional cell to be prepared, and DU 174 initiates and performs at least one additional LTM preparation procedure with CU 172 to prepare the additional cell for LTM, wherein each of the LTM preparation procedures is similar to procedure 390.

[0106] In some implementations, CU 172 and DU 174 perform LTM preparation procedures 2, ..., N similar to procedure 390 to prepare cells 2, ..., N, respectively. In some implementations, CU 172 includes cell IDs 2, ..., N in CU-DU messages 2, ..., N, similar to the first CU-DU message, during LTM preparation procedures 2, ..., N. During LTM preparation procedures 2, ..., N, DU 174 generates LTM DU configurations 2, ..., N for cells 2, ..., N, and includes LTM DU configurations 2, ..., N in DU-CU messages 2, ..., N, as described for LTM DU configuration 1. Upon receiving CU-DU messages 2, ..., N, DU-CU messages 2, ..., N respond to CU-DU messages 2, ..., N, respectively. "N" is an integer greater than one. For example, "N" can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16. In another example, the maximum number of "N" is 4, 8, 16, or 32. In some implementations, LTM DU configuration 1 is used for LTM DU configuration 2, ..., N.

[0107] In a further implementation, CU 172 and DU 174 perform a single LTM preparation procedure (i.e., LTM preparation procedure 390) to prepare cells 1, 2, ..., N. In some implementations, DU 174 includes the LTM DU configurations 1, 2, ..., N for cells 1, 2, ..., N in the first DU to CU message. In some implementations, DU 174 includes the cell IDs 1, 2, ..., N associated with the LTM DU configurations 1, 2, ..., N in the first DU to CU message. In some implementations, CU 172 determines to perform LTM preparation procedure 390, and CU 172 includes the cell IDs 1, 2, ..., N in the first CU to DU message to request DU 174 to prepare cells 1, 2, ..., N for LTM respectively.

[0108] In some implementations, after receiving LTM DU configurations 2, ..., N from DU 174, CU 172 includes LTM DU configurations 2, ..., N in a first container. In some implementations, CU 172 includes LTM DU configurations 2, ..., N in elements 2, ..., N, and also includes elements 2, ..., N in a first container. In some implementations, CU 172 includes the LTM IDs (i.e., ID 2, ..., N) used to identify LTM DU configurations 2, ..., N in the RRC reconfiguration message. In some implementations, CU 172 includes ID 2, ..., N in a first container. In some implementations, CU 172 includes ID 2, ..., N and LTM DU configurations 2, ..., N in elements 2, ..., N in a first add or modify list.

[0109] In some implementations, CU 172 assigns IDs 2, ..., N to LTM DU configurations 2, ..., N respectively. In a further implementation, CU 172 receives IDs 2, ..., N from the first DU to CU message of process 390 from DU 174. In yet another further implementation, CU 172 receives IDs 2, ..., N from DU to CU messages 2, ..., N of LTM preparation processes 2, ..., N respectively from DU 174.

[0110] In some implementations, CU 172 performs an LTM ID allocation procedure similar to procedure 392 with DU 174 for each of LTM DU configurations 2, ..., N. In a further implementation, CU 172 includes the association between IDs 2, ..., N and LTM DU configurations 2, ..., N in a third CU-DU message and indicates this association. In some implementations, DU 174 associates LTM DU configurations 2, ..., N with IDs 2, ..., N respectively. In yet another further implementation, CU 172 includes the association between cell IDs 2, ..., N and IDs 2, ..., N respectively in a third CU-DU message and indicates this association. In some implementations, DU 174 associates LTM DU configurations 2, ..., N with IDs 2, ..., N based on the associations between cell IDs 2, ..., N and IDs 2, ..., N respectively, and the associations between cell IDs 2, ..., N and LTM DU configurations 2, ..., N respectively. In other implementations, CU 172 includes ID 2, ..., N, cell ID 2, ..., N, and / or LTM DU configuration 2, ..., N in the second CU to DU message, as described above. Therefore, the third CU to DU message is omitted. In a further implementation, CU 172 includes ID 2, ..., N in the first CU to DU message and indicates that ID 2, ..., N are associated with cell ID 2, ..., N, respectively. In some implementations, DU 174 includes ID 2, ..., N in LTM DU configuration 2, ..., N. Therefore, CU 172 does not include ID 2, ..., N in the RRC reconfiguration message, the first container, and / or element 2, ..., N.

[0111] In a further implementation, DU 174 assigns IDs 2, ..., N. In some implementations, DU 174 includes IDs 2, ..., N in the first DU to CU message of process 390. In yet another implementation, DU 174 includes IDs 2, ..., N in DU to CU messages 2, ..., N of LTM preparation process 2, ..., N. In some implementations, CU 172 includes IDs 2, ..., N in the RRC reconfiguration message. In other implementations, DU 174 includes IDs 2, ..., N in LTM DU configuration 2, ..., N. Therefore, CU 172 does not include the ID (e.g., LTM ID) identifying each of LTM DU configurations 2, ..., N in the RRC reconfiguration message, the first container, and / or element 1.

[0112] In some implementations, CU 172 generates a second container including LTM DU configuration 2, ..., N or element 2, ..., N, instead of using the first container. In some implementations, similar to events 316 and 318, CU 172 sends an additional RRC reconfiguration message including the second container to UE 102 via DU 174. In response, similar to events 320 and 322, UE 102 sends an additional RRC reconfiguration complete message to CU 172 via DU 174. In some implementations, the second container is a second add-or-modify list (e.g., the ltm-ConfigToAddModList field, LTM-ConfigToAddModList IE, ltm-CandidateConfigToAddModList field, or LTM-CandidateConfigToAddModList IE), and each of elements 2, ..., N is an add-or-modify IE (e.g., the ltm-ConfigToAddMod field, LTM-ConfigToAddMod IE, ltm-CandidateConfigToAddMod field, or LTM-CandidateConfigToAddMod IE). In some implementations, UE 102 receives the second add-or-modify list and stores it together with the first add-or-modify list (e.g., in a variable stored in its random access memory (RAM)).

[0113] In some implementations, DU 174 includes cell IDs 2, ..., N in LTM DU configurations 2, ..., N to identify cells 2, ..., N. In some implementations, each of cell IDs 2, ..., N is a PCI. In a further implementation, LTM DU configurations 2, ..., N include cell indices 2, ..., N indexed for cell IDs 2, ..., N or cells 2, ..., N respectively. In some implementations, CU 172 prepares cells 2, ..., N for LTM in process 390, CU 172 sets cell indices 2, ..., N to different values, and includes cell indices 2, ..., N in the first CU-to-CU-to-DU message 308. In some implementations, CU 172 prepares cells 2, ..., N in an additional LTM preparation process, CU 172 sets cell indices 2, ..., N to different values, and includes cell indices 2, ..., N in the CU-to-DU message of the additional LTM preparation process. CU 172 sets cell indices 1, ..., N to different values. In some implementations, the cell IDs 1, ..., N in the LTM DU configuration 1, ..., N are different from the cell IDs 1, ..., N in the CU to DU message described above.

[0114] In some implementations, each of the LTM DU configurations 1, ..., N includes physical configuration parameters, MAC configuration parameters, RLC configuration parameters, and / or L1 measurement configuration. In some implementations, each of the LTM DU configurations 1, ..., N is a CellGroupConfig IE (e.g., as defined in 3GPP TS 38.331). In further implementations, each of the LTM DU configurations 1, ..., N includes configuration parameters included in a CellGroupConfig IE (e.g., as defined in 3GPP TS 38.331). In still further implementations, multiple configuration parameters in each of the LTM DU configurations include a specific cell configuration (e.g., SpCellConfig IE) and / or one or more SCell configurations (e.g., SCellConfig IE). In some implementations, the LTM DU configurations 1, ..., N are CellGroupConfig IEs (e.g., as defined in 3GPP TS 38.331). In a further implementation, LTM DU configuration 1, ..., N includes the configuration parameters in CellGroupConfig IE.

[0115] In some implementations, CU 172 includes one or more additional LTM CU configurations in at least one of elements 2, ..., N, the first container, or the second container. Each of the additional LTM CU configurations is associated with a specific LTM DU configuration in LTM DU configurations 2, ..., N. In some implementations, the additional LTM CU configurations are similar to LTMCU configuration 1.

[0116] In some implementations, CU 172 determines to release LTM DU configuration M (or element M in element 1, ..., M) from LTM DU configurations 1, ..., N, where 1 ≤ M ≤ N. In response to this determination, CU 172 sends an RRC reconfiguration message to UE 102 via DU 174 to instruct UE 102 to release LTM DU configuration M or element M. In some implementations, CU 172 generates a release list including an ID (i.e., LTM ID) M for releasing LTM DU configuration M or element M, and includes this release list in the RRC reconfiguration message. In response to the RRC reconfiguration message, UE 102 releases LTM DU configuration M or element M and sends an RRC reconfiguration complete message to CU 172 via DU 174. In response to this determination, CU 172 sends a CU-DU message to DU 174 to instruct DU 174 to release LTM DU configuration M. In some implementations, to instruct DU 174 to release the LTM DU configuration M, CU 172 includes the cell ID M or ID (i.e., LTM ID) M in the release instruction (e.g., a field or IE) in the CU-DU message. In response, DU 174 releases the LTM DU configuration M and sends a DU-CU message to CU 172. In some implementations, the CU-DU message and the DU-CU message are respectively a UE context modification request message and a UE context modification response message.

[0117] In other implementations, DU 174 determines to release LTM DU configuration K. In response to this determination, DU 174 sends a DU-to-CU message to CU 172 to release LTM DU configuration K. In some implementations, to indicate the release of LTM DU configuration K, DU 174 includes the cell ID K or ID (i.e., LTM ID) K (e.g., 1 ≤ K ≤ N) in the release indication (e.g., a field or IE) of the DU-to-CU message. Upon receiving the DU-to-CU message (e.g., in response to this), CU 172 generates a release list including the ID (i.e., LTM ID) K to release LTM DU configuration K or element K, and sends an RRC reconfiguration message including the release list to UE 102 via DU 174. In response, UE 102 releases LTM DU configuration K or element K and sends an RRC reconfiguration complete message to UE 102 via DU 174. In some implementations, CU 172 sends a CU to DU message to DU 174 in response to a DU to CU message. In some implementations, the DU to CU message and the CU to DU message are the UE context modification request message and the UE context modification confirmation message, respectively.

[0118] In some implementations, after UE 102 receives 318 RRC reconfiguration or sends 320 RRC reconfiguration complete message, UE 102 sends 324 at least one measurement report to DU 174, similar to event 304. In some implementations, DU 174 sends 326 a DU-CU message including at least one measurement report to CU 172, similar to event 306. In other implementations, DU 174 does not send at least one measurement report to CU 172. In some implementations, at least one measurement report includes 324 an L1 measurement report or an L3 measurement report, as described with respect to event 304. In some implementations, UE 102 sends 324 at least one measurement report to DU 174 on PUCCH and / or PUSCH, similar to event 304. In a further implementation, UE 102 sends 324 at least one MAC CE including at least one measurement report to DU 174, similar to event 304. In some implementations, UE 102 does not send L1 measurement reports to DU 174 in the format of RRC messages.

[0119] In some implementations, UE 102 sends at least one measurement report (324) to DU 174 according to at least one measurement configuration. The at least one measurement configuration configures UE 102 to perform measurements and report measurement results. CU 172 sends at least one measurement configuration to UE 102 via DU 174. In some implementations, CU 172 sends one or more RRC messages (e.g., RRCReconfiguration messages) including at least one measurement configuration to UE 102 via DU 174. In some implementations, the one or more RRC messages include a 316 RRC reconfiguration message. UE 102 performs measurements on one or more reference signals according to at least one measurement configuration. In some implementations, the one or more reference signals include one or more SSBs and / or one or more CSI-RSs. In some implementations, UE 102 obtains at least one L1 measurement result (324) and / or at least one L3 measurement result from the measurements and includes the at least one L1 measurement result and / or at least one L3 measurement result in at least one measurement report. DU 174 transmits one or more reference signals on cell 124A, cell 1, and / or cell 2, ..., N. In some implementations, the one or more reference signals are CSI-RS or SSB.

[0120] In some implementations, the at least one measurement configuration includes a 304 L3 measurement configuration (e.g., a MeasConfigIE). In a further implementation, the at least one measurement configuration includes, or is an L1 measurement configuration, as described above. In yet another implementation, the L1 measurement configuration is a CSI-MeasConfigIE (e.g., as defined in 3GPP TS 38.331). In yet another implementation, the L1 measurement configuration includes an RS resource configuration and / or a reporting configuration. UE 102 sends a 324 L1 measurement report to DU 174 on UL resources (e.g., Physical Uplink Control Channel (PUCCH) resources or Physical Uplink Shared Channel (PUSCH) resources) according to the reporting configuration. DU 174 receives the L1 measurement report on the UL resources according to the reporting configuration. In some implementations, the reporting configuration is similar to a CSI-ReportConfigIE. In other implementations, each reporting configuration is a specially defined RRCIE. In some implementations, each report configuration configures periodic reporting and / or event-triggered reporting of L1 measurement results.

[0121] In some implementations, the L1 measurement report is a CSI report. In other implementations, the L1 measurement report is a MACCE. In some implementations, each measurement report includes one or more RS resource indicators and / or one or more quantized measurement values. UE 102 performs measurements on RS or RS resources according to RS resource configuration and / or reporting configuration, and obtains quantized measurement values ​​from the measurements. In some implementations, the RS resource indicator instructs UE 102 to perform measurements on RS or RS resources or to obtain quantized measurement values. In some implementations, the RS resource indicator includes one or more SSB resource indicators (SSBRI) and / or one or more CSI-RS resource indicators (CRI). In some implementations, the quantized measurement values ​​include one or more L1-RSRP values ​​and / or one or more L1-SINR values.

[0122] In a further implementation, at least one measurement configuration includes a specially defined type of measurement configuration (e.g., an LTM measurement configuration as defined in 3GPP TS). In some implementations, the specially defined measurement configuration includes a reference signal resource configuration that configures the resources in which DU 174 transmits reference signals. For example, the reference signal resource configuration includes CSI-RS and / or SSB. In one implementation, the reference signal resource configuration is a CSI-ResourceConfig IE. In some implementations, as described above, the specially defined measurement configuration includes a measurement report configuration. UE 102 transmits a measurement report to DU 174 on the PUCCH or MAC CE according to the measurement report configuration. DU 174 receives the measurement report on the PUCCH or MAC CE according to the measurement report configuration. In some implementations, the measurement report is an L1 measurement report or a specially defined measurement report (e.g., an LTM measurement report). In some implementations, the specially defined measurement configuration includes specially defined configuration parameters (e.g., as defined in 3GPP TS).

[0123] In response to receiving at least one measurement report 324, DU 174 generates a first LTM command to activate LTM DU configuration 1 (i.e., the first LTM command instructs UE 102 to apply LTM DU configuration 1 or perform a serving cell change for cell 1). DU 174 then sends the first LTM command 330 to UE 102. In some implementations, DU 174 sends the first LTM command to UE 102 on cell 124A. In a further implementation, DU 174 sends the first LTM command to UE 102 on cell 124D. In some implementations, DU 174 includes ID 1 in the first LTM command to indicate LTM DU configuration 1 or element 1, and UE 102 determines LTM DU configuration 1 or element 1 based on ID 1.

[0124] In some implementations, DU 174 includes cell index 1, which is indexed to cell ID 1 in the first LTM command. UE 102 determines LTM DU configuration 1 or element 1 based on cell index 1. Before receiving the first LTM command, UE 102 retrieves cell index 1 from LTM DU configuration 1 or element 1 and establishes association 1 between cell index 1 and LTM DU configuration 1 or element 1. In other words, UE 102 decodes LTM DU configuration 1 or element 1 to obtain cell index 1 before receiving the first LTM command. Therefore, UE 102 determines LTM DU configuration 1 or element 1 based on cell index 1 and association 1. Before receiving the first LTM command, UE 102 retrieves cell indices 2, ..., N from LTM DU configurations or elements 2, ..., N, and establishes associations 2, ..., N between cell indices 2, ..., N and LTM DU configurations or elements 2, ..., N, respectively. In other words, before receiving the first LTM command, UE 102 decodes the LTM DU configuration or elements 2, ..., N to obtain cell indices 2, ..., N.

[0125] In a further implementation, DU 174 includes cell ID 1 in the first LTM command, where cell ID 1 identifies cell 1. In some implementations, cell ID 1 in the first LTM command is the same as cell ID 1 in the first CU to DU message. In some implementations, DU 174 determines cell ID 1 (e.g., PCI) in the first LTM command from cell ID 1 (e.g., CGI) received in the first CU to DU message. UE 102 determines (e.g., identifies) LTM DU configuration 1 or element 1 based on cell ID 1. Before receiving the first LTM command, UE 102 retrieves cell ID 1 from LTM DU configuration 1 or element 1 and establishes an association 1 between cell ID 1 and LTM DU configuration 1 or element 1. In other words, UE 102 decodes LTM DU configuration 1 or element 1 to obtain cell ID 1 before receiving the first LTM command. Therefore, UE 102 identifies LTM DU configuration 1 or element 1 based on cell ID 1 (e.g., from the first LTM command) and association 1. Before receiving the first LTM command, UE 102 retrieves cell IDs 2, ..., N from LTM DU configurations or elements 2, ..., N, and establishes associations 2, ..., N between cell IDs 2, ..., N and LTM DU configurations or elements 2, ..., N respectively. In other words, UE 102 decodes LTM DU configurations or elements 2, ..., N to obtain cell IDs 2, ..., N before receiving the first LTM command. In some implementations, DU 174 has a mapping table for storing the mapping relationships between PCI 1, ..., N and CGI 1, ..., N for cells 1, ..., N respectively.

[0126] In a further implementation, DU 174 includes a bitmap in the first LTM command to activate LTM DU configuration 1, instead of ID 1 or cell index 1. The number of bits in the bitmap is greater than or equal to "N". In some implementations, bits 1, ..., N correspond to cell index 1, ..., N, ID 1, ..., N, LTM DU configuration 1, ..., N, or element 1, ..., N, respectively, and DU 174 sets the corresponding bit (e.g., bit 1) in the bitmap to a first value to indicate cell index 1, ID 1, LTM DU configuration 1, or element 1. In some implementations, UE 102 determines cell index 1, ID 1, LTM DU configuration 1, or element 1 based on bit 1 in the bitmap that is set to a first value. In some implementations, bits 0, ..., N-1 correspond to cell index 1, ..., N, ID 1, ..., N, LTM DU configuration 1, ..., N, or element 1, ..., N, respectively, and DU 174 sets the corresponding bit (e.g., bit 0) in the bitmap to a first value to indicate cell index 1, ID 1, LTM DU configuration 1, or element 1. In some implementations, UE 102 determines cell index 1, ID 1, LTM DU configuration 1, or element 1 based on bit 0 in the bitmap that is set to the first value. In some implementations, DU 174 sets the remaining bits in the bitmap to a second value to indicate that the remaining portions of LTM DU configurations 1, ..., N are not activated. In some implementations, the first value is one, and the second value is zero. In a further implementation, the first value is zero, and the second value is one. In some implementations, if DU 174 determines that LTM DU configuration L is activated or that the serving cell for UE 102 is changed to cell L, then DU 174 sets the corresponding bit in the bitmap (e.g., bit L or bit L-1) to a first value and sets the remaining bits to a second value, where 1 ≤ L ≤ N. In some implementations, DU 174 sets at most one bit in the bitmap to the first value.

[0127] After determining or identifying LTM DU configuration 1 or element 1, UE 102 applies LTM DU configuration 1 and / or LTM CU configuration after receiving the first LTM command (e.g., in response to this).

[0128] In some implementations, at least one measurement report 324 (e.g., an L1 measurement report or a specially defined measurement report) includes at least one measurement result of the first cell, the TRP of the first cell, or a reference signal transmitted on the first cell. In some implementations, the reference signal is CSI-RS or SSB. DU 174 determines to activate LTM DU configuration 1 or send a first LTM command based on at least one measurement result. In some implementations, DU 174 determines to activate LTM DU configuration 1 when at least one measurement result is higher than a second predetermined threshold. In some implementations, the at least one measurement result includes an L1-RSRP value, an L1-RSRQ value, and / or an L1-SINR value. In other implementations, at least one measurement result includes an RSRP value, an RSRQ value, and / or a SINR value from a specially defined measurement report. In some implementations, the second predetermined threshold is different from the first predetermined threshold. In some implementations, the second predetermined threshold is greater than the first predetermined threshold. In this case, at least one measurement result indicates that the first cell is suitable for communication with UE 102. In some implementations, the second predetermined threshold is equal to the first predetermined threshold. In this case, the at least one measurement indicates that the first cell consistently exceeds either the second predetermined threshold or the first predetermined threshold. This indicates that the first cell is suitable for communication with UE 102. Therefore, when the signal strength or quality of the first cell is higher than the second predetermined threshold of UE 102, DU 174 determines to activate LTM DU configuration 1.

[0129] In some implementations, at least one measurement report (e.g., an L3 measurement report) includes at least one measurement result of the first cell 324 and 326. CU 172 determines to activate LTM DU configuration 1 or send a first LTM command because at least one measurement result indicates that the signal strength or quality of the first cell is higher than a second predetermined threshold. The second predetermined threshold is different from the first predetermined threshold. In a further implementation, the second predetermined threshold is greater than the first predetermined threshold. In such an implementation, at least one measurement report indicates that the signal strength or quality of the first cell 326 is suitable for communication with UE 102. In yet another implementation, the second predetermined threshold is equal to the first predetermined threshold. In such an implementation, at least one measurement report indicates that the signal strength or quality of the first cell 326 is consistently higher than either the second predetermined threshold or the first predetermined threshold. This also indicates that the first cell is suitable for communication with UE 102. Therefore, in response to the signal strength or quality of the first cell exceeding the second predetermined threshold, CU 172 determines to activate LTM DU configuration 1. In response to this determination, CU 172 sends a fourth CU-DU message (328) to DU 174 to activate LTM DU configuration 1 or trigger a serving cell change for UE 102 to cell 1. In some implementations, CU 172 includes ID 1 in the fourth CU-DU message. In a further implementation, CU 172 includes cell index 1 in the fourth CU-DU message. In response to the fourth CU-DU message, DU 174 sends a first LTM command (330) to UE 102 and optionally sends a fourth DU-CU message to CU 172. In some implementations, CU 172 includes cell index 1 in the fourth CU-DU message. In some implementations, DU 174 determines to activate LTM DU configuration 1 based on cell index 1. In a further implementation, CU 172 includes cell ID 1 in the fourth CU-DU message. Therefore, DU 174 determines to activate LTM DU configuration 1 based on cell ID 1. In a further implementation, CU 172 includes ID 1 in the fourth CU to DU message. In some implementations, DU 174 determines the activation of LTM DU configuration 1 based on ID 1. In a further implementation, the fourth CU to DU message and the fourth DU to CU message are the UE context modification request message and the UE context modification response message, respectively. In yet another further implementation, the fourth CU to DU message and / or the fourth DU to CU message are specially defined interface messages (e.g., the F1AP message defined in 3GPP TS 38.473).

[0130] In some implementations, when it is determined that LTM DU configuration 1 is activated or the first LTM command 330 is sent, DU 174 sends a DU-to-CU message 329 to CU 172 for performing LTM. In a further implementation, DU 174 includes cell ID 1 or ID 1 (i.e., LTM ID) in the DU-to-CU message 329 to instruct DU 174 to activate LTM DU configuration 1 or trigger a fast serving cell change (i.e., LTM serving cell change). In yet another further implementation, DU sends the DU-to-CU message 329 to CU 172 before or after sending the LTM command 330.

[0131] In some implementations, UE 102 receives 330 from DU 174 carrying a first LTM command containing a MAC CE included in the MAC PDU. In some implementations, the MAC CE is a specially defined MAC CE (e.g., as defined in 3GPP TS 38.321). In some implementations, DU 174 includes a subheader identifying the specially defined MAC CE in the MAC PDU, and UE 102 identifies the specially defined MAC CE in the MAC PDU based on this subheader. In some implementations, the subheader includes a logical channel ID or an extended logical channel ID to identify the specially defined MAC CE. For example, the logical channel ID or the extended logical channel ID is a specially defined ID (e.g., as defined in 3GPP TS 38.321). In a further implementation, the first LTM command is a DCI received by UE 102 from DU 174 on the PDCCH. DU 174 generates a CRC for the DCI, scrambles the CRC using the first C-RNTI of UE 102, and transmits the 330 DCI and the scrambled CRC on the PDCCH. In some implementations, the DCI format exists (e.g., as defined in 3GPP TS 38.212). In further implementations, the DCI format is a specially defined DCI format (e.g., as defined in 3GPP TS 38.212).

[0132] In some implementations, DU 174 does not perform security protection (e.g., integrity protection and / or encryption) on the first LTM command. This speeds up the processing of the first LTM command in UE 102 because UE 102 does not perform security checks (e.g., decryption and / or integrity checks) on the first LTM command.

[0133] In some implementations, after receiving the first LTM command, UE 102 sends a 331 acknowledgment to DU 174 on cell 124A or cell 124D to indicate that UE 102 has received the first LTM command. In some implementations, the acknowledgment is a HARQACK. In some implementations, the acknowledgment is a MAC CE. For example, the MAC CE is an existing MAC CE (e.g., defined in 3GPP specification 38.321). As a further example, the MAC CE is a specially defined MAC CE (e.g., as defined in 3GPP specification 38.321). In yet another implementation, the acknowledgment is a PUCCH transmission.

[0134] In some implementations, CU 172 sends an RRC reconfiguration message 316 in response to receiving an L3 measurement report for the first cell (306). In a further implementation, to configure UE 102 to send an L3 measurement report (304), CU 172 sends a first RRC reconfiguration message to UE 102 including an L3 measurement configuration (MeasConfig IE). In some implementations, DU 174 sends a first LTM command (330) in response to an L1 measurement report for the first cell (324). In some implementations, to configure UE 102 to send an L1 or specially defined measurement report (324), CU 172 sends a second RRC reconfiguration message to UE 102 including an L1 or specially defined measurement configuration. In some implementations, the first RRC reconfiguration message and the second RRC reconfiguration message are the same message (i.e., the same instance). In a further implementation, the first RRC reconfiguration message and the second RRC reconfiguration message are different messages. In a further implementation, CU172 sends a second RRC reconfiguration message (316). In this further implementation, the second RRC reconfiguration message is a different message (i.e., not the same instance).

[0135] Upon receiving the first LTM command (e.g., in response to this), UE 102 accesses the first cell 332. UE 102 identifies LTM DU configuration 1 based on ID 1, cell ID 1, or cell index 1 received in the first LTM command, and applies LTM DU configuration 1 to communicate with DU 174 on the first cell. In some implementations, UE 102 disconnects from cell 124A after receiving the first LTM command or after sending acknowledgment 331 (e.g., in response to this). In some implementations, UE 102 ceases communication on cell 124A after receiving 330 to the first LTM command or after sending acknowledgment 331 (e.g., in response to this). In some implementations, UE 102 accesses the first cell by performing a random access procedure with DU 174 on the first cell in response to receiving the first LTM command. In other implementations, upon receiving the first LTM command (e.g., in response to it), UE 102 skips the random access procedure and sends a first transmission (e.g., a PUSCH transmission or a PUCCH transmission) to DU 174 on the first cell.

[0136] In some implementations, DU 174 configures UE 102's access to the first cell in LTM DU configuration 1, including whether UE 102 performs a random access procedure. When a first LTM command (e.g., a first LTM instruction) is received, UE 102 determines whether to perform a random access procedure on the first cell according to LTM DU configuration 1. If LTM DU configuration 1 configures UE 102 to perform a random access procedure, UE 102 performs a 332 random access procedure on the first cell to connect to the first cell. For example, LTM DU configuration 1 includes a reconfiguration with synchronization configuration (e.g., ReconfigurationWithSync IE) to configure UE 102 to perform a random access procedure when UE 102 receives an LTM command for the first cell. In some implementations, in LTM DU configuration 1, DU 174 configures UE 102 to skip the random access procedure when the LTM serving cell changes to the first cell. In this scenario, upon receiving the first LTM command, UE 102 skips the random access procedure and sends a 332 first transmission (e.g., a PUSCH transmission or a PUCCH transmission) to DU 174 on the first cell. In some implementations, DU 174 excludes reconfiguration with synchronization configuration in LTM DU configuration 1 to configure UE 102 to skip the random access procedure when the LTM serving cell changes to the first cell.

[0137] In a further implementation, LTM DU configuration 1 includes a reconfiguration or random access configuration with a synchronization configuration. In such cases, DU 174 configures UE 102 in the LTM command to perform a random access procedure on the first cell. In some implementations, UE 102 performs a 332 random access procedure on the first cell according to the first LTM command. In a further implementation, DU 174 includes an indication (e.g., a field) indicating skipping the random access procedure in the first LTM command. In response to this indication or the first LTM command including the indication, UE 102 skips the random access procedure and directly transmits a first transmission (e.g., a PUSCH transmission or a PUCCH transmission) on the first cell to access the first cell. In a further implementation, DU 174 excludes the indication in the first LTM command for configuring UE 102 to perform a random access procedure. In response to the first LTM command exclusion indication, UE 102 performs a random access procedure on the first cell to access the first cell. In a further implementation, DU 174 includes a timing advance value in the first LTM command to indicate skipping the random access procedure. In response to receiving the timing advance value or a first LTM command including the timing advance value, UE 102 skips the random access procedure and uses the timing advance value to send a first transmission on the first cell to access the first cell. In a further implementation, DU 174 excludes the timing advance value used to configure UE 102 to perform a random access procedure in the first LTM command. In response to the first LTM command excluding the timing advance command, UE 102 performs a random access procedure on the first cell to access the first cell.

[0138] In some implementations, the random access procedure is a four-step random access procedure. In some implementations, the random access procedure is a two-step random access procedure. In a further implementation, the random access procedure is a contention-free random access procedure. In an even further implementation, the random access procedure is a contention-based random access procedure. In the case of a four-step random access procedure, UE 102 sends message 3, including the UE identifier, to DU 174 via the first cell during the random access procedure. In response to message 3, DU 174 sends a conflict resolution message (e.g., message 4) to UE 102. In the case of a two-step random access procedure, UE 102 sends message A, including the UE identifier, to DU 174 via the first cell during the random access procedure. In response to message A, DU 174 sends a conflict resolution message (e.g., message B) to UE 102. In some implementations, when UE 102 receives a conflict resolution message from DU 174 on the first cell, UE 102 determines that UE 102 has successfully completed the random access procedure (i.e., UE 102 has successfully accessed the first cell). In some implementations, LTM DU configuration 1 includes a second C-RNTI, and the UE identifier is the second C-RNTI of UE 102. In some implementations, the conflict resolution message is a PDCCH transmission destined for the second C-RNTI. In a further implementation, LTM DU configuration 1 does not include a C-RNTI, and the UE identifier is the first C-RNTI. In a further implementation, the conflict resolution message is a PDCCH transmission destined for the first C-RNTI.

[0139] When LTM DU configuration 1 includes a dedicated random access preamble, the random access procedure is a contention-free random access procedure. In this case, UE 102 sends the dedicated random access preamble to DU 174 via the first cell. When UE 102 receives a random access response including the ID of the dedicated random access preamble from DU 174 on the first cell, UE 102 successfully completes the random access procedure (i.e., UE 102 successfully accesses the first cell).

[0140] If DU 174 configures UE 102 to perform the random access procedure as described above on the first cell, then when DU 174 receives message 3, message A, or a special preamble during the random access procedure, DU 174 detects that UE 102 has accessed the first cell. In some implementations, DU 174 configures UE 102 to skip the random access procedure, and DU 174 receives a first transmission indicating that UE 102 has accessed the first cell.

[0141] In some implementations, UE 102 transmits a first transmission (e.g., a PUSCH transmission) on the first cell using a UL grant. In some implementations, the first LTM command includes a UL grant. In a further implementation, when UE 102 performs an LTM serving cell change to the first cell in response to a first LTM command, UE 102 receives a first DCI including a UL grant on the PDCCH of the first cell. In some implementations, when UE 102 switches to the first cell in response to a first LTM command, UE 102 attempts to receive the first DCI or a UL grant by monitoring one or more PDCCHs on the first cell according to LTM DU configuration 1. When monitoring one or more PDCCHs on the first cell, UE 102 receives the first DCI and its CRC on the PDCCH. If LTM DU configuration 1 includes a second C-RNTI, UE 102 uses the CRC and the second C-RNTI to determine that the first DCI was transmitted for UE 102. In the absence of a second C-RNT in LTM DU configuration 1, UE 102 uses CRC and the first C-RNTI to determine that the first DCI was sent for UE 102.

[0142] In some implementations, CU 172 sends at least one first TCI state configuration to UE 102 via DU 174. In some implementations, each first TCI state configuration configures a TCI state for UE 102 to transmit and / or receive data and / or control signals on a first cell. In some implementations, each TCI state associates one or two DL RSs with a corresponding QCL type, and the DL RSs are associated with a specific cell in cell 1, ..., N. In some implementations, CU 172 receives a DU-to-CU message including the first TCI state configuration from DU 174 and sends an RRC message including the first TCI state configuration to UE 102 via DU 174. In a further implementation, DU 174 includes the first TCI state configuration in a serving DU configuration (e.g., CellGroupConfig IE) and includes the serving DU configuration in the DU-to-CU message. In some implementations, DU 174 includes LTM DU configuration 1 in the first interface protocol IE / field and service DU configuration in the second interface protocol IE / field of the DU to CU message.

[0143] In some implementations, the first interface protocol IE / field is defined as part of the format of the DU to CU message. CU 172 includes the service DU configuration in the RRC message. In some implementations, CU 172 avoids including the service DU configuration in the LTM container (e.g., the first container). In other implementations, CU 172 includes the first TCI state configuration in an element of the LTM, an LTM add or modify list, or a container, similar to element 1, the first add or modify list, or the first container, respectively. In some implementations, the RRC message is an RRC reconfiguration message 316, 318, or another RRC reconfiguration message (…). FIG. 3 (Not shown in the image). In some implementations, the DU to CU message is message 312, message 314, UE context modification response message, or UE context modification request message. In some implementations, DU 174 also includes the first TCI state configuration in LTM DU configuration 1. In a further implementation, DU 174 avoids including the first TCI state configuration in LTM DU configuration 1.

[0144] In some implementations, the first interface protocol IE / field is the first F1AP IE / field, and the second interface protocol IE / field is the second F1AP IE / field. In some implementations, one of the first F1AP IE / field and the second F1AP IE / field is an F1AP CellGroupConfig IE / field, while the other is not. In some implementations, DU 174 includes the first F1AP IE / field in the DU-to-CU RRC information IE and includes the second F1AP IE / field in the DU-to-CU RRC information IE of the DU-to-CU message. In a further implementation, neither the first F1AP IE / field nor the second F1AP IE is an F1AP CellGroupConfig IE / field. In yet another implementation, the second F1AP IE / field is the DU-to-CU RRC information IE, while the first F1AP IE / field is a specially defined IE used to include LTM DU configuration.

[0145] In some implementations, upon receiving a first LTM command (e.g., in response to this) or upon accessing the first cell 332, UE 102 uses some or all of the first TCI state configurations to monitor one or more PDCCHs on the first cell. In some implementations, each first TCI state configuration includes a TCI state ID identifying the corresponding TCI state configuration. For example, the first TCI state configuration includes TCI state configuration 1, ..., L, where L is a positive integer greater than zero. TCI state configurations 1, ..., L include TCI state IDs 1, ..., L, respectively identifying TCI state configuration 1, ..., L. DU 174 includes TCI state ID 1 in the first LTM command to instruct UE 102 to apply TCI state configuration 1 for communication on the first cell. Upon receiving the first LTM command (e.g., in response to this), UE 102 uses TCI state configuration 1 to access and / or communicate on the first cell based on TCI state ID 1. For example, UE 102 uses TCI state configuration 1 to monitor one or more PDCCHs and / or send a first transmission. In some implementations, DU 174 detects that UE 102 has accessed a first cell based on TCI state configuration 1 and communicates with UE 102 on the first cell. For example, DU 174 receives a first transmission from UE 102 on the first cell based on TCI state configuration 1.

[0146] In some implementations, DU 174 includes TCI State ID 2 in the first LTM command to instruct UE 102 to apply TCI State Configuration 2 in addition to TCI State ID 1 for communication on the first cell. Upon receiving the first LTM command (e.g., in response to it), UE 102 uses TCI State Configurations 1 and 2 to access and / or communicate on the first cell based on TCI State ID 1 and TCI State ID 2. For example, UE 102 uses TCI State Configuration 1 to monitor one or more PDCCHs on the first cell and uses TCI State Configuration 2 to send a first transmission on the first cell. In another example, UE 102 uses both TCI State Configuration 1 and TCI State Configuration 2 to monitor one or more PDCCHs on the first cell and sends a first transmission on the first cell using either TCI State Configuration 1 or TCI State Configuration 2. In some implementations, DU 174 detects that UE 102 has accessed the first cell and is communicating with UE 102 on the first cell based on TCI State Configuration 1 and / or TCI State Configuration 2. For example, DU174 receives a first transmission from UE 102 on the first cell based on one of TCI state configuration 1 and TCI state configuration 2.

[0147] In a further implementation, DU 174 does not include the TCI state ID in the first LTM command. In such a case, upon receiving the first LTM command (e.g., in response to it), UE 102 communicates with the first DU on the first cell using at least one first TCI state. In some implementations, DU 174 is configured to detect UE 102 accessing the first cell based on the first TCI state and communicate with UE 102 on the first cell.

[0148] In some implementations, before sending the first LTM command, DU 174 sends one or more activation commands to activate some or all of the first TCI state configuration. In some implementations, each activation command is a MAC CE. In a further implementation, each activation command is a DCI. In some implementations, DU 174 includes TCI state ID 1 and / or TCI state ID 2 in the activation command to activate TCI state configuration 1 and / or TCI state configuration 2, respectively. Therefore, when UE 102 receives the activation command, it determines or identifies that TCI state configuration 1 and / or TCI state configuration 2 are active. In other implementations, DU 174 includes all TCI state IDs of the first TCI state configuration in the activation command. Therefore, when UE 102 receives the activation command, it determines or identifies that the first TCI state configuration is active. In some implementations, DU 174 avoids including TCI state IDs of TCI state configurations that DU 174 has not yet activated for UE 102 in the first LTM command. In some implementations, DU 174 includes cell ID 1 or cell index 1 in the activation command. Based on cell ID 1 or cell index 1, and one or more TCI state IDs in the activation command, UE 102 determines that the activation command activates one or more TCI state configurations in the first TCI state configuration, wherein each TCI state ID identifies a specific TCI state configuration in the TCI state configuration.

[0149] In some implementations, UE 102 uses one or more TCI state configurations to communicate with DU 174 on cell 124A (e.g., events 302, 304, 318, 320, 324, 330). In some implementations, each TCI state configuration configures the TCI state for UE 102 to send and / or receive data and / or control signals on cell 124A. In some implementations, UE 102 stops using the TCI configuration upon receiving a first LTM command.

[0150] After successfully accessing the first cell, UE 102 communicates 336 with DU 174 on the first cell using LTM DU configuration 1 and / or a reference LTM DU configuration, and communicates with CU 172 via DU 174. In this case, DU 174 communicates 336 with UE 102 on the first cell using LTM DU configuration 1. In some implementations, UE 102 communicates 336 PUSCH transmissions, PDSCH transmissions, PUCCH transmissions, PDCCH transmissions, and / or sounding reference signal (SRS) transmissions with DU 174 on the first cell. In some implementations, UE 102 uses some or all of the first TCI state configuration to perform 336 communication with DU 174. Similarly, DU 174 uses some or all of the first TCI state configuration to perform 336 communication with UE 102. In some implementations, DU 174 includes one or more additional TCI state configurations in LTM DU configuration 1. In some implementations, DU 174 sends one or more activation commands (336) to UE 102 via a first cell to activate an additional TCI state configuration. Upon receiving the activation command, UE 102 determines that the additional TCI state configuration is active. In some implementations, each activation command is a MAC CE. In a further implementation, each activation command is a DCI. After receiving the activation command, UE 102 uses the additional TCI state configuration to communicate with DU 174 on the first cell. Similarly, after sending the activation command, DU 174 uses the additional TCI state configuration to communicate with UE 102 on the first cell.

[0151] When UE 102 receives the reference LTM DU configuration as described above, UE 102 communicates with DU 174 on the first cell 336 according to at least a portion of LTM DU configuration 1 and the reference LTM DU configuration. In other words, UE 102 communicates with DU 174 according to the configuration parameters in LTM DU configuration 1 and the reference LTM DU configuration 336. Similarly, DU 174 communicates with UE 102 on the first cell 336 according to at least a portion of LTM DU configuration 1 and the reference LTM DU configuration. In other words, DU 174 communicates with UE 102 according to the configuration parameters in LTM DU configuration 1 and the reference LTM DU configuration 336.

[0152] If UE 102 receives neither LTM CU Configuration 1 nor Reference LTM CU Configuration, UE 102 communicates with CU 172 via DU 174 using the serving CU configuration 336. Correspondingly, if CU 172 neither sends LTM CU Configuration 1 nor Reference CU Configuration to UE 102, CU 172 communicates with UE 102 via DU 174 using the serving CU configuration 336. If UE 102 receives both LTM CU Configuration 1 and Reference LTM CU Configuration from CU 172, UE 102 communicates with CU 172 via DU 174 using LTMCU Configuration 1 and a reference LTM CU configuration not enhanced by LTM CU Configuration 1 (e.g., at least a portion thereof). In this case, CU 172 communicates with UE 102 via DU 174 using LTM CU configuration 1 and a reference LTM CU configuration (e.g., at least a portion thereof) that is not enhanced by LTM CU configuration 1.

[0153] If UE 102 receives LTM CU configuration 1 from CU 172 but does not receive a reference LTM CU configuration, UE 102 communicates with CU 172 via DU 174 using LTM CU configuration 1 336. In this case, CU 172 communicates with UE 102 via DU 174 using LTM CU configuration 1 336. If LTM CU configuration 1 is a complete configuration, UE 102 and CU 172 communicate with each other via DU 174 using LTM CU configuration 1 instead of the serving CU configuration 336. In some implementations, if UE 102 does not receive a reference LTM CU configuration from base station 104, UE 102 determines that LTM CU configuration 1 is a complete configuration. Accordingly, if CU 172 determines to configure LTM CU configuration 1 as a complete configuration, CU 172 does not send a reference LTM CU configuration to UE 102. In some implementations, CU 172 includes a first indication (e.g., a field or IE) 336 in LTMCU configuration 1, the first container, element 1, or the RRC reconfiguration message to indicate that LTM CU configuration 1 is a complete configuration. If LTMCU configuration 1 is an incremental configuration used to enhance the service CU configuration, then UE 102 and CU 172 communicate with each other via DU 174 using LTM CU configuration 1 and at least a portion of the service CU configuration not enhanced by LTM CU configuration 1 336. In some implementations, if UE 102 does not receive a reference LTM CU configuration from base station 104, then UE 102 determines that LTM CU configuration 1 is an incremental configuration to enhance the service CU configuration. Accordingly, if CU 172 determines that it wants to configure LTM CU configuration 1 as an incremental configuration to enhance the service CU configuration, then CU 172 will not send the reference LTM CU configuration to UE 102. In some implementations, CU 172 indicates that LTM CU Configuration 1 is an incremental configuration used to enhance the service CU configuration by excluding the first indication 316 in LTM CU Configuration 1, the first container, element 1, and / or the RRC reconfiguration message. Alternatively, CU 172 includes a second indication (e.g., a field or IE) in LTM CU Configuration 1, the first container, element 1, or the RRC reconfiguration message to indicate that LTM CU Configuration 1 is an incremental configuration used to enhance the service CU configuration. In some implementations, CU 172 indicates that LTM CU Configuration 1 becomes a complete configuration by excluding the second indication in LTM CU Configuration 1, the first container, element 1, and / or the RRC reconfiguration message.

[0154] If UE 102 receives a reference LTM CU configuration from CU 172 but does not receive LTM CU configuration 1, UE 102 communicates with CU 172 via DU 174 using the reference LTM CU configuration 336. In this case, CU 172 communicates with UE 102 via DU 174 using the reference LTM CU configuration 336. If the reference LTM CU configuration is a complete configuration, UE 102 and CU 172 communicate with each other via DU 174 using the reference LTM CU configuration instead of the serving CU configuration 336. In some implementations, UE 102 and CU 172 determine that reference LTM CU configuration 1 is a complete configuration (e.g., as defined in 3GPP TS 38.331). In some implementations, CU 172 includes a first indication (e.g., a field or IE) 316 in the reference LTM CU configuration, first container, or RRC reconfiguration message to indicate that the reference LTM CU configuration is a complete configuration. If the reference LTM CU configuration is an incremental configuration for enhancing the service CU configuration, then UE 102 and CU 172 communicate with each other via DU 174 336 using the reference LTM CU configuration and at least a portion of the service CU configuration not enhanced by the reference LTM CU configuration. In some implementations, CU 172 indicates 316 that the reference LTM CU configuration is an incremental configuration for enhancing the service CU configuration by excluding a first indication in the reference LTM CU configuration, the first container, element 1, and / or the RRC reconfiguration message. Alternatively, CU 172 includes a second indication (e.g., a field or IE) 316 in the reference LTM CU configuration, the first container, element 1, or the RRC reconfiguration message to indicate that the reference LTM CU configuration is an incremental configuration for enhancing the service CU configuration. In some implementations, CU 172 indicates 316 that the reference LTM CU configuration becomes a complete configuration by excluding the second indication in the reference LTM CU configuration, the first container, element 1, and / or the RRC reconfiguration message.

[0155] If UE 102 receives neither the reference LTM CU configuration nor LTM CU configuration 1 from CU 172, UE 102 communicates with CU 172 via DU 174 using the serving LTM CU configuration 336. In this case, CU 172 communicates with UE 102 via DU 174 using the serving LTM CU configuration 336.

[0156] In some implementations, UE 102 sends an RRC message (e.g., an RRC reconfiguration complete message) to CU 172 via DU 174 and the first cell to instruct UE 102 to apply LTM DU configuration 1. In some implementations, UE 102 performs the 332 random access procedure, and UE 102 includes the RRC message in message 3 or message A. Alternatively, UE 102 sends the RRC message after completing the random access procedure. In some implementations, UE 102 skips the 332 random access procedure and includes the RRC message in a PUSCH transmission within at least one PUSCH transmission. In some implementations, UE 102 maintains communication with base station 104 on cell 124A (i.e., UE 102 does not disconnect from cell 124A), and UE 102 sends the RRC message to base station 104 via cell 124A. When DU 174 receives an RRC message, DU 174 sends the RRC message to CU 172.

[0157] In a further implementation, UE 102 avoids sending an RRC message to base station 104 in response to applying LTM DU configuration 1 or receiving a first LTM command. In some implementations, UE 102 includes or sends data in message 3, message A, or PUSCH transmission as described above. In a further implementation, UE 102 generates a MAC PDU and / or RLCPDU including data, and sends or includes the MAC PDU and / or RLC PDU in PUSCH transmission. In some implementations, the data is a PDCP PDU, SDAP PDU, LTE Positioning Protocol (LPP) PDU, RRC PDU, and / or NAS PDU. The RRC PDU includes a UL-DCCH-Message that excludes the RRC reconfiguration completion message. The NAS PDU includes a Mobility Management (MM) message or a Session Management (SM) message. In some implementations, the MM message is a 5G MM message or a 6G MM message, and the SM message is a 5G SM message or a 6GSM message. When DU 174 receives data, it sends the data to CU 172.

[0158] In some implementations, when DU 174 determines that UE 102 (332 or 336) has successfully connected to the first cell, DU 174 sends a DU-to-CU message (e.g., an access success message) to CU 172 (e.g., the CP of CU 172). In a further implementation, DU 174 includes the cell ID 1 of the first cell in the DU-to-CU message. In some implementations, the cell ID is PCI or CGI. Therefore, CU 172 determines that UE 102 (334) has connected to the first cell upon receiving the DU-to-CU message. When DU 174 determines that UE 102 (332 or 336) has successfully connected to the first cell, DU 174 sends a DL data delivery status message or frame to CU 172 (e.g., the UP of CU 172). In some implementations, when CU 172 receives message 329 DU to CU, CU 172 stops or suspends sending DL data for UE 102 to DU 174 until it receives message 334 DU to CU. In some implementations, CU 172 stops or suspends sending 330 and / or 332 because DU 174 does not buffer DL data for UE 102 during LTM execution. After receiving message 334 DU to CU, CU 172 resumes or continues sending DL data for UE 102 to DU 174. In a further implementation, CU 172 receives message 329 DU to CU, and CU 172 continues sending DL data for UE 102 to DU 174. In yet another further implementation, CU 172 continues sending 330 and / or 332 because DU 174 buffers DL data for UE 102 during LTM execution. When DU 174 detects that UE 102 has accessed cell 1, or after that, DU 174 sends DL data to UE 102 via cell 1.

[0159] In some implementations, when it is determined that UE 102 is connected to the first cell, sends the first LTM command 330, or receives the acknowledgment 331, DU 174 stops communicating with UE 102 on cell 124A and / or releases the resources of cell 124A configured for UE 102.

[0160] In some implementations, DU 174 generates some or all of LTM DU configuration 1 and / or LTM DU configuration 2, ..., N as a complete configuration to replace the serving DU configuration. If LTM DU configuration 1 is a complete configuration, then UE 102 and DU 174 communicate with each other based on LTM DU configuration 1 instead of the serving DU configuration 336. In some implementations, DU 174 includes an indication that LTM DU configuration 1 is a complete configuration in LTM DU configuration 1. In some implementations, in each of LTM DU configurations 2, ..., N, DU 174 includes an indication indicating that the corresponding DU configuration is a complete configuration. In a further implementation, each of the indications in LTM DU configurations 1, ..., N is a field or IE (i.e., the same field or IE). In a further implementation, CU 172 includes a single indication indicating that LTM DU configurations 1 and / or 2, ..., N are complete configurations in the RRC reconfiguration message 316 and 318. In a further implementation with a second container, CU 172 includes a single indication indicating that LTM DU configurations 2, ..., N are complete configurations in an additional RRC reconfiguration message. In yet another implementation, CU 172 includes a single indication indicating that LTM DU configurations 1 and / or 2, ..., N are complete configurations in a first container. In yet another implementation, for each of LTM DU configurations 2, ..., N, CU 172 includes a specific indication indicating that the corresponding DU configuration is complete in the first container. In some implementations with a second container, CU 172 includes a single indication indicating that DU configurations 2, ..., N are complete configurations in the second container. In yet another implementation, CU 172 includes an indication indicating that LTM DU configuration 1 is complete in element 1. In some implementations, in each of elements 2, ..., N, CU 172 includes an indication indicating that the corresponding LTM DU configuration is complete. In some implementations, UE 102 determines whether LTM DU configuration 1 and / or LTM DU configuration 2, ..., N are complete configurations based on the above indications. In some implementations, each of the above indications differs from the fullConfig field (e.g., as defined in the current 3GPP TS). In some implementations, each of the above indications is (e.g., as defined in the 3GPP TS) the fullConfig field. If LTM DU configuration 1 is a complete configuration, UE 102 does not apply 336 reference LTM DU configuration if it receives (e.g., UE 102 receives 318 RRC reconfiguration message) from base station 104. In some implementations, DU 174 does not include 310 reference LTM DU configuration in the first DU to CU message.

[0161] In some implementations, DU 174 generates LTM DU configuration 1 and / or LTM DU configuration 2, ..., N as incremental configurations that enhance a reference LTM DU configuration (e.g., a portion thereof). In other words, DU 174 generates LTM DU configuration 1, ..., N based on a reference LTM DU configuration. For example, if LTM DU configuration 1 is an incremental configuration, then UE 102 and DU 174 utilize LTM DU configuration 1 to enhance a reference LTM DU configuration (e.g., a portion thereof). Therefore, UE 102 and DU 174 communicate with each other based on LTM DU configuration 1 and the unenhanced portion of the reference LTM DU configuration 336. In some implementations, LTM DU configuration 1 and / or 2, ..., N, the first container, the second container, or element 1, ..., N excludes indications that LTM DU configuration 1 and / or 2, ..., N is a complete configuration, instead indicating that LTM DU configuration 1 and / or 2, ..., N is an incremental configuration. In some implementations, UE 102 determines that each of LTM DU configurations 1 and / or 2, ..., N is an incremental configuration based on the indication that it is excluded from LTM DU configurations 1 and / or 2, ..., N, the first container, the second container, or elements 1 and / or 2, ..., N.

[0162] In some implementations, if UE 102 does not receive a reference LTM DU configuration for LTM DU configuration 1 and / or LTM DU configuration 2, ..., N, then UE 102 determines that LTM DU configuration 1 and / or LTM DU configuration 2, ..., N are complete configurations. Correspondingly, if DU 174 does not obtain a reference LTM DU configuration for UE 102 (i.e., DU 174 does not generate a reference LTM DU configuration for UE 102 and / or does not receive a reference LTM DU configuration for UE 102 from CU 172), then DU 174 generates LTM DU configuration 1 and / or LTM DU configuration 2, ..., N as complete configurations.

[0163] In a further implementation, if UE 102 does not receive a reference LTM DU configuration for LTM DU configuration 1 and / or LTM DU configuration 2, ..., N, then UE 102 determines that LTM DU configuration 1 and / or LTM DU configuration 2, ..., N are incremental configurations for enhancing the service DU configuration. In this case, UE 102 communicates with DU 174 336 based on at least a portion of the service DU configuration that is not enhanced by LTM DU configuration 1. Correspondingly, if DU 174 does not obtain a reference LTM DU configuration for UE 102 (i.e., DU 174 does not generate a reference LTM DU configuration for UE 102 and / or receives a reference LTM DU configuration for UE 102 from CU 172), then DU 174 generates LTM DU configuration 1 and / or LTM DU configuration 2, ..., N as incremental configurations for enhancing the service DU configuration. In such cases, DU 174 communicates with UE 102 336 based on at least a portion of LTM DU configuration 1 and service DU configuration.

[0164] In some implementations, UE 102 uses a UE MAC entity (e.g., MAC 204B) to communicate with the DUMAC entity (e.g., MAC 204B) of DU 174 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). In some implementations, UE 102 resets the UE MAC entity after receiving a first LTM command or in response to it and before performing the 332 random access procedure or communicating 336 with DU 174 via the first cell. In some implementations, DU 174 resets the DUMAC entity after sending the first LTM command, receiving 331 to acknowledge or determine that UE 102 is connected to the first cell (e.g., in response to it).

[0165] In some implementations, when UE 102 resets the UE MAC entity, UE 102 performs at least one of the following actions (i.e., UE MAC reset or full UE MAC reset) on the UE MAC entity: (i) initializing the Bj of the configured logical channel to zero, stopping one or more timers, assuming the timeAlignmentTimer has expired if UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), setting the new data indicator (e.g., NDI) of the UL HARQ process to a value of 0, setting the NDI of the HARQ process ID to a value of 0 for monitoring the PDCCH in sidelink resource allocation mode 1, refreshing the Msg3 buffer, and refreshing the MSGA buffer; (ii) Cancel (if any) one of the following triggered processes: scheduling request, buffer status report, power margin report, persistent LBT failure, BFR, sidelink buffer status report, pre-emptive buffer status report, timing advance report, recommended bit rate query, configured uplink authorization acknowledgment, configured sidelink authorization acknowledgment, expected protection symbol query or location measurement gap activation / deactivation request, (iii) refresh the soft buffer used for the DL HARQ process, (iv) for each in the DL HARQ process, treat the next received transmission of the TB as the initial transmission, (v) release (if any) the temporary C-RNTI, and (vi) reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0166] In some implementations, when DU 174 resets the DU MAC entity, DU 174 performs at least one of the following actions on the DU MAC entity (i.e., DU MAC reset or full DU MAC reset): (i) stopping one or more timers, (ii) assuming that the timeAlignmentTimer initiated and / or maintained by DU 174 for UE 102 has expired if UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), (iii) setting the NDI of the DL HARQ process to a value of 0, (iv) refreshing the soft buffer of the UL HARQ process, (v) treating the next received transmission of TB as the initial transmission for each of the UL HARQ processes, and (vi) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0167] In some implementations, UE 102 determines to partially or completely reset the UE MAC entity. In some implementations, when UE 102 resets the UE MAC entity as described above, UE 102 completely resets the UE MAC entity (i.e., a full UE MAC reset). In a full UE MAC reset, UE 102 performs some or all of the actions described above. In a further implementation, when UE 102 resets the UE MAC entity as described above, UE 102 partially resets the UE MAC entity (i.e., a partial UE MAC reset). In a partial UE MAC reset, UE 102 performs a subset or part of some or all of the actions in a full UE MAC reset.

[0168] In some implementations, a partial UE MAC reset includes at least one of the following actions: (i) if UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), the timeAlignmentTimer of UE 102 is considered to have expired; (ii) the Msg3 buffer is flushed; (iii) the MSGA buffer is flushed; (iv) the temporary C-RNTI is released (if any); and (v) one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0169] In some implementations, a partial UE MAC reset further includes canceling at least one of the following triggering procedures: (i) scheduling request, buffer status report, power margin report, persistent LBT failure, BFR, sidelink buffer status report, pre-emptive buffer status report, timing advance report, recommended bit rate query, configured uplink authorization confirmation, configured sidelink authorization confirmation, expected protection symbol query, and positioning measurement gap activation / deactivation request.

[0170] In some implementations, a partial UE MAC reset further includes at least one of the following actions: (i) stopping the first portion of one or more timers and retaining the remainder of one or more timers, (ii) setting the New Data Indicator (NDI) for the UL HARQ procedure to the value 0, (iii) setting the NDI for the HARQ procedure ID to the value 0 for monitoring the PDCCH in sidelink resource allocation mode 1, (iv) refreshing the soft buffer for the DL HARQ procedure, and (v) for each DL HARQ procedure, treating the next received transmission of the TB as the first transmission.

[0171] In some implementations, DU 174 determines to partially or completely reset the DU MAC entity. In a further implementation, when DU 174 resets the DU MAC entity as described above, DU 174 completely resets the DU MAC entity (i.e., a full DU MAC reset). In a full DU MAC reset, DU 174 performs some or all of the actions described above. In yet another further implementation, when DU 174 resets the DU MAC entity as described above, DU 174 partially resets the DU MAC entity (i.e., a partial DU MAC reset). In a partial DU MAC reset, DU 174 performs a subset or part of some or all of the actions in a full DU MAC reset.

[0172] In some implementations, a partial DU MAC reset includes at least one of the following actions in a partial MAC reset: (i) if UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), then the timeAlignmentTimer initiated and / or maintained by DU 174 for UE 102 is considered to have expired, and (ii) one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0173] In some implementations, a partial DU MAC reset includes at least one of the following actions (i.e., DU MAC reset) for a MAC entity: (i) stopping the first portion of one or more timers and retaining the remainder of one or more timers, (ii) setting the NDI of the DL HARQ process to the value 0, (iii) flushing the soft buffer for the UL HARQ process, (iv) treating the next received transmission of the TB as the first transmission for each of the UL HARQ processes, and (v) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0174] In a further implementation, UE 102 avoids resetting the UE MAC entity in response to receiving the first LTM command. Similarly, DU 174 avoids resetting the DU MAC entity after sending the first LTM command, receiving 331 to acknowledge or determine that UE 102 is connected to the first cell (e.g., in response to this). In other words, UE 102 uses the UE MAC entity (not reset) to communicate with DU 174 on the first cell. Similarly, DU 174 uses the DU MAC entity (not reset) to communicate with UE 102 on the first cell during or after the random access procedure, or after determining that UE 102 is connected to the first cell 332.

[0175] In some implementations, UE 102 uses at least one UE RLC entity (e.g., RLC 206B) to communicate RLC PDUs (e.g., events 302, 304, 318, 320, 324, 330, and / or 331) to at least one DU RLC entity (e.g., RLC 206B) of DU 174. In some implementations, UE 102 reconstructs some or all of the at least one UE RLC entity after receiving the first LTM command 332 or in response to it, and before performing a random access procedure or communicating 336 with DU 174 via the first cell. In some implementations, DU 174 reconstructs some or all of the at least one DU RLC entity after sending the first LTM command, receiving 331 to acknowledge or determine that UE 102 is connected to the first cell (e.g., in response to it).

[0176] In some implementations, LTM DU configuration 1 optionally includes one or more RLC reconstruction indications (e.g., a reestablishRLC field) configuring UE 102 to rebuild some or all of at least one UERLC entity. In some implementations, if LTM DU configuration 1 includes an RLC reconstruction indication configuring UE 102 to rebuild a first UE RLC entity among at least one UE RLC entities used by UE 102 to communicate the RLCPDU to DU 174, then UE 102 rebuilds the first UE RLC entity in response to the RLC reconstruction indication and the first LTM command. In some implementations, UE 102 rebuilds the first UE RLC entity 332 before performing a random access procedure or communicating 336 with DU 174 via the first cell. In a further implementation, UE 102 rebuilds the first UE RLC entity concurrently with or after performing the 332 random access procedure. Otherwise, if LTM DU configuration 1 does not include an RLC reconstruction indication, UE 102 avoids rebuilding the first UE RLC entity in response to the first LTM command.

[0177] In some implementations, when UE 102 reconstructs the first UE RLC entity, UE 102 performs at least one of the following actions on the first UE RLC entity: (i) discarding the RLC SDU, RLC SDU segment, and RLC PDU (if any); (ii) stopping and resetting any running timers; and / or (iii) resetting state variables to their initial values. In some implementations, state variables and timers (e.g., as defined in 3GPP TS 38.322) are...

[0178] Otherwise, if LTM DU configuration 1 does not include an RLC reconstruction indication for the first UE RLC entity, then UE 102 avoids reconstructing the first UE RLC entity upon or when the first LTM command is received. In other words, UE 102 avoids performing the action for reconstructing the first UE RLC entity of UE 102 upon or when the first LTM command is received. In some implementations, if LTM DU configuration 1 or element 1 does not include an RLC reconstruction indication but includes an indication that configuration 1 is fully configured, then UE 102 reconstructs the first UE RLC entity of UE 102 upon or when the first LTM command is received. Otherwise, if LTM DU configuration 1 or element 1 does not include an RLC reconstruction indication and an indication that configuration 1 is fully configured, then UE 102 avoids reconstructing the first UE RLC entity upon or when the first LTM command is received.

[0179] Similarly, DU 174 reconstructs some or all of at least one DU RLC entity (e.g., NR RLC 206B) used by DU 174 to communicate with at least one UERLC entity of UE 102 (e.g., events 302, 304, 318, 320, 324, 330 and / or 331) in response to an RLC reconstruction instruction. In some implementations, DU 174 reconstructs the first DU RLC entity among at least one DURLC entity after sending a first LTM command, receiving an acknowledgment of the first LTM command from UE 102, or determining that UE 102 is connected to the first cell. In some implementations, the acknowledgment is a HARQ ACK. In a further implementation, the acknowledgment is a MAC CE. In yet another implementation, the acknowledgment is a PUCCH transmission. In some implementations, when base station 104 reconstructs the first DU RLC entity, DU 174 performs at least one of the following actions on the first DU RLC entity: (i) discarding any existing RLC SDU, RLC SDU segment, and RLC PDU; (ii) stopping and resetting a running timer; and / or (iii) resetting the state variables to their initial values.

[0180] In some implementations, state variables and timers (e.g., as defined in 3GPP TS 38.322).

[0181] In other implementations, UE 102 avoids rebuilding some or all of at least one UERLC entity in response to receiving a first LTM command. Similarly, DU 174 avoids rebuilding some or more of at least one DU RLC entity after sending the first LTM command, receiving 331 to acknowledge or determine that UE 102 is connected to the first cell (e.g., in response to this). In other words, UE 102 uses some or all of at least one UE RLC entity (not rebuilt) to communicate with DU 174 on the first cell. For example, some or all of at least one UE RLC entity includes a first UE RLC entity and / or a second UE RLC entity. Similarly, DU 174 uses some or all of at least one DU RLC entity (not rebuilt) to communicate with UE 102 on the first cell during or after the random access procedure or after determining that UE 102 is connected to the first cell 332. For example, some or all of at least one DU RLC entity includes a first DU RLC entity and / or a second DURLC entity.

[0182] In some implementations, UE 102 uses at least one UE PDCP entity (e.g., PDCP 210) to communicate 302 UL PDCP PDU and / or DL ​​PDCP PDU with at least one CU PDCP entity (e.g., PDCP 210) of CU 172. In some implementations, after receiving or in response to a first LTM command, UE 102 performs a PDCP recovery procedure for some or all of the at least one UE PDCP entity. For example, after receiving or in response to receiving a first LTM command, UE 102 performs a PDCP recovery procedure for the first UE PDCP entity among the at least one UE PDCP entities. During the PDCP recovery procedure, UE 102 may optionally rebuild the first UE PDCP entity. In some implementations, after performing or in response to performing the PDCP recovery procedure, UE 102 retransmits at least a portion of the UL PDCPPDU to CU 172 via DU 174 and the first cell. Similarly, after sending the first LTM command or in response to sending the first LTM command, CU 172 performs some or all of the PDCP recovery procedures for at least one CU PDCP entity. For example, after sending the first LTM command or in response to sending the first LTM command, CU 172 performs the PDCP recovery procedure for the first CU PDCP entity among at least one CU PDCP entity. In some implementations, CU 172 performs PDCP recovery procedure 329 or 334 for the first CU PDCP entity in response to receiving a DU to CU message. In a further implementation, CU 172 performs the PDCP recovery procedure for the first CU PDCP entity in response to receiving a DL data delivery status message. During the PDCP recovery process, CU 172 may optionally reconstruct the first CU PDCP entity. In some implementations, after performing the PDCP recovery procedure or in response to performing the PDCP recovery procedure, CU 172 retransmits 336 of at least a portion of the DL PDCP PDU to UE 102 via DU 174 and the first cell.

[0183] In a further implementation, UE 102 avoids rebuilding some or all of at least one UE PDCP entity in response to receiving a first LTM command. For example, some or all of the at least one UE PDCP entity includes a first UE PDCP entity and / or a second UE PDCP entity. Similarly, after receiving a 329 or 340 DU to CU message (e.g., in response to this) or after receiving a DL data delivery status message (e.g., in response to this), CU 172 avoids rebuilding some or more of at least one CU PDCP entity. In other words, UE 102 uses some or all of at least one UE PDCP entity (not rebuilt) to communicate with CU 172 via DU 174 and the first cell. For example, some or all of the at least one UE PDCP entity includes a first UE PDCP entity and / or a second UE PDCP entity. Similarly, CU 172 uses some or all of at least one CU PDCP entity (not rebuilt) to communicate with UE 102 via DU 174 and the first cell. For example, some or all of at least one CU PDCP entity includes a first CU PDCP entity and / or a second CU PDCP entity.

[0184] In some implementations, after determining that UE 102 is connected to the first cell, CU 172 sends a 338CU to DU message (e.g., a UE Context Modification Request message) to DU 174 to instruct DU 174 to stop communicating with UE 102 and / or release or suspend resources configured for UE 102 in cell 124A. In some implementations, DU 174 stops communicating with UE 102 in cell 124A and / or releases or suspends resources configured for UE 102 in cell 124A, and sends a 340 DU to CU 172 (e.g., a UE Context Modification Response message). Events 338 (optional) and 340 (optional) in... FIG. 3 This is collectively referred to as the resource release process 396.

[0185] In some implementations, events 344, 346, 348, 350, 351, 352, 354, and / or 356, respectively, occur after or simultaneously with communication with DU 174 on the first cell. UE 102 sends at least one measurement report (344) to DU 174. The at least one measurement report includes at least one measurement result for the second cell (i.e., cell 2). This at least one measurement result indicates that the second cell is suitable for communication with UE 102 and / or the first cell is not suitable for communication with UE 102. Upon receiving at least one measurement report (e.g., in response to this), DU 174 determines to activate LTM DU configuration 2 and generates a second LTM command to activate LTM DU configuration 2 (i.e., the second LTM command instructs UE 102 to apply LTM DU configuration 2). Then, DU 174 sends 350 second LTM commands to UE102 on the first cell.

[0186] In some implementations, in response to determining that LTM DU configuration 2 is activated or sending a second LTM command, DU 174 sends a DU-to-CU message 349 to CU 172 instructing LTM execution. In some implementations, DU 174 includes cell ID 2 or ID 2 (i.e., LTM ID) in the DU-to-CU message 349 to instruct DU 174 to activate LTM DU configuration 2. In some implementations, the DU sends the DU-to-CU message 349 to CU 172 before or after sending the LTM command 350.

[0187] At least some of the discussions of events 324, 326, 328, 330, 331, 332, 334 and / or 336 may generally be applied to events 344, 346, 348, 350, 351, 352, 354 and / or 356. For example, “Cell 124A”, “First LTM Command”, “First Cell”, “ID 1”, “LTM DU Configuration 1” and / or “LTM CU Configuration 1” are replaced with “First Cell”, “Second LTM Command”, and “Second Cell”, “ID 2”, “LTM DU Configuration 2” and / or “LTM CU Configuration 2”, respectively.

[0188] Events 344, 346, 348, 350, 351, 352, and 354 are in FIG. 3 These are collectively referred to as LTM execution process 398. Events 304, 306, 390, 392, 394, 324, 326, 328, 329, 330, 331, 332, 334, 336, 396, 398, and 356 are in... FIG. 3This is collectively referred to as the LTM DU configuration and / or activation process 380.

[0189] Next reference FIG. 4 In scenario 400, base station 104 includes CU 172, source DU (S-DU) 174A, and target DU (T-DU) 174B. S-DU 174A operates cell 124A and optionally additional cells, while T-DU 174B operates the first cell (e.g., cell 124C). Scenario 400 is similar to scenario 300. In some implementations, the discussion of scenario 300 often also applies to scenario 400. The differences between scenarios 300 and 400 are described below.

[0190] Initially, UE 102 uses the serving DU to communicate with S-DU 174A on cell 124A 402, and communicates with CU 172 via S-DU 174A. S-DU 174A is the serving DU, similar to... FIG. 3In S-DU 174A, during communication 402, UE 102 sends at least one measurement report (e.g., an L3 measurement report) via S-DU 174A to CU 172, numbers 404 and 406. Based on the at least one measurement report, CU 172 determines cells 1, ..., N to prepare for LTM for UE 102 (e.g., operated by T-DU 174B), where N is a positive integer greater than 0 or 1. Cells 1, ..., N are identified by cell IDs 1, ..., N, respectively. In response to the determination, CU 172 and T-DU 174B perform LTM preparation procedure 490 to (e.g., request T-DU 174B) prepare cells 1, ..., N for LTM for UE 102. In some implementations, N is a positive integer greater than zero or 1. During LTM preparation, similar to event 308, CU 172 sends a CU-DU message (490) to T-DU 174B, including cell IDs 1, ..., N, to request T-DU 174B to prepare cells 1, ..., N for LTM for UE 102. In response, similar to event 310, T-DU 174B sends a DU-DU message (490) to CU 172, including LTM DU configurations 1, ..., N. LTM DU configurations 1, ..., N configure cells 1, ..., N for LTM, respectively. Specifically, LTM DU configurations 1, ..., N include configuration parameters for communication on cells 1, ..., N. In some implementations, the CU-DU message and DU-CU message in process 490 are respectively a UE Context Setup Request message and a UE Context Setup Response message. Similar to LTM DU configuration delivery procedure 394, CU 172 then sends LTM configuration 1, ..., N in the RRC reconfiguration message during LTM configuration delivery procedure 494. In some implementations, T-DU 174B includes cell indices 1, ..., N in LTM DU configuration 1, ..., N respectively. In some implementations, CU 172 sets cell indices 1, ..., N to different values ​​and includes cell indices 1, ..., N in CU-DU message 490.

[0191] In some implementations, after performing the 490 LTM preparation procedure, CU 172 and T-DU 174B perform an additional LTM-like preparation procedure to prepare cells N+1, ..., N+M for LTM for UE 102. M is a positive integer greater than zero. In some implementations, similar to events 404 and 406, CU 172 determines one or more measurement reports received from UE 102 via S-DU 174A. During the additional LTM preparation procedure, CU 172 sends a CU-DU message to T-DU 174B including cell IDs N+1, ..., N+M to request T-DU 174B to prepare cells N+1, ..., N+M for LTM for UE 102. Cell IDs N+1, ..., N+M identify cells N+1, ..., N+M, respectively. In response to the CU-DU message, T-DU 174B sends a DU-DU message to CU 172 including LTM DU configurations N+1, ..., N+M. The LTM DU configurations N+1, ..., N+M configure the cells N+1, ..., N+M for LTM, respectively. Specifically, the LTM DU configurations N+1, ..., N+M include configuration parameters for communication on cells N+1, ..., N+M, respectively. CU 172 then sends LTM DU configurations N+1, ..., N+M in an RRC reconfiguration message during an additional LTM configuration delivery process.

[0192] In some implementations, LTM preparation procedure 490 is a UE context establishment procedure, and additional LTM preparation procedure is a UE context modification procedure.

[0193] In some implementations, CU 172 and S-DU 174A perform a 380 procedure with UE 102, such as for FIG. 3 As described above. In procedure 380, CU 172 and S-DU 174A perform procedures 390 and / or 392 to prepare the S-DU174A cell for LTM for UE 102. In some implementations, the procedure or for... FIG. 3 Describe the value N of 380 and its relation to FIG. 4The described value N may be the same or different. In some implementations, in procedure 390, CU 172 receives 310 a first DU-to-CU message including a reference LTM configuration from S-DU 174A. In a further implementation, CU 172 and S-DU 174A do not perform procedure 380 with UE 102. In one implementation, CU 172 and S-DU 174A perform a 488 reference LTM DU configuration query procedure to obtain the reference LTM DU configuration. In procedure 488, CU 172 sends a 460 CU-to-DU message to S-DU 174A to request or query the reference LTM DU configuration. In some implementations, CU 172 will include an indication in the CU-to-DU message to request or query the reference LTM DU configuration. In response to the indication or CU-to-DU message 460, S-DU 174A sends a 462 DU-to-CU message including the reference LTM DU configuration to CU 172. In some implementations, the indication is a reference LTM DU configuration query indication. In a further implementation, the indication is an LTM indication, and CU 172 includes the query indication (e.g., GNB-DU configuration query IE) in the CU-DU message. After receiving the reference LTM DU configuration (i.e., in process 390 or process 488), CU 172 includes the reference LTM DU configuration (e.g., received from S-DU 174A) in the CU-DU message during the LTM preparation process in process 490. T-DU 174B generates LTM DU configurations 1, ..., N based on the reference LTM DU configuration received from CU 172. In this case, T-DU 174B does not include the reference LTM DU configuration in the DU-CU message during process 490. In the case of an additional LTM preparation process, T-DU 174B does not include the reference LTM DU configuration in the DU-CU message during the additional LTM preparation process. In some implementations, CU 172 and T-DU 174B do not include the reference LTM DU configuration in the CU-DU message during the additional LTM preparation process. In the case of the additional LTM preparation process, T-DU 174B generates LTM DU configurations N+1, ..., N+M based on the reference LTM DU configuration received from CU 172.

[0194] In some implementations, CU 172 does not provide a reference LTM DU configuration to T-DU 174B during LTM preparation procedure 490. In this case, T-DU 174B generates a reference LTM DU configuration and generates LTM DU configurations 1, ..., N based on the reference LTM DU configuration. In this case, T-DU 174B includes the reference LTM DU configuration in the DU-to-CU message in procedure 490. CU 172 sends the reference LTM DU configuration in the RRC reconfiguration message in procedure 490. In the case of an additional LTM preparation procedure, T-DU 174B generates LTM DU configurations N+1, ..., N+M based on the reference LTM DU configuration. In some implementations, T-DU 174B does not include the reference LTM DU configuration in the DU-to-CU message during the additional LTM preparation procedure. In some implementations, the reference LTM DU configuration generated by T-DU 174B differs from the reference LTM DU configuration generated by S-DU 174A. In a further implementation, the reference LTM DU configuration generated by T-DU 174B is the same as the reference LTM DU configuration generated by S-DU 174A.

[0195] In some implementations, CU 172 includes the LTM DU configurations 1, ..., N of process 380 in the CU to DU message of process 490, and T-DU 174B considers or generates LTM DU configurations 1, ..., N and / or N+1, ..., N+M based on the configurations in the LTM DU configurations of process 380.

[0196] In some implementations, the LTM DU configuration X of process 380 includes at least one Reference Signal (RS) resource configuration X, where 1 ≤ X ≤ N. Each RS resource configuration X configures one or more RSs or one or more RS resources associated with cell X of S-DU 174A. RSs include SSBs and / or CSI-RSs. RS resources include SSB resources and / or CSI-RS resources. In some implementations, each RS resource configuration X includes an RS resource configuration ID. In some implementations, RS resource configuration X is (e.g., similar to) a CSI-ResourceConfig IE. In some implementations, the LTM DU configuration X includes a CSI-MeasConfig IE, and the CSI-MeasConfig IE includes a CSI-ResourceConfig IE. T-DU 174B generates at least one reporting configuration 1 for reporting measurement results of RSs or RS resources on cell 1 of T-DU 174B, and includes the reporting configuration 1 in the LTM DU configuration 1. In some implementations, report configuration 1 is (e.g., similar to) CSI-ReportConfig IE. In some implementations, the T-DU 174B considers or generates at least one RS resource configuration 1 based on RS resource configuration X and includes that RS resource configuration 1 in LTM DU configuration 1. In some implementations, the T-DU 174B includes RS resource configuration X in RS resource configuration 1. In other implementations, the T-DU 174B includes each of RS resource configurations X in RS resource configuration 1, differing only in the RS resource configuration ID within RS resource configuration X. The T-DU 174B assigns an RS resource configuration ID to each RS resource configuration 1 (e.g., including RS resource configuration X) and includes that RS resource configuration ID in the corresponding RS resource configuration.

[0197] In some implementations, Report Configuration 1 configures one or more UL resources (e.g., PUCCH or PUSCH resources) for UE 102 on cell 1 to transmit measurement results. In some implementations, each Report Configuration 1 includes one or more RS resource configuration IDs identifying one or more RS resource configurations included in RS resource configuration 1. After UE 102 performs an LTM serving cell change from cell 124A to cell 1, UE 102 communicates with S-DU 174B (i.e., T-DU 17B becomes UE 102's S-DU) and sends measurement results regarding UL resources to S-DU 174B via cell 1 according to Report Configuration 1. Accordingly, S-DU 174B receives measurement results regarding UL resources from UE 102 via cell 1 according to Report Configuration 1. In some implementations, each measurement result includes one or more RS resource indicators and / or one or more quantized measurement values. UE 102 performs measurements on an RS or RS resource according to RS resource configuration 1 and / or reporting configuration 1, and obtains quantized measurement values ​​from the measurements. In some implementations, an RS resource indicator instructs UE 102 to perform measurements or obtain quantized measurement values ​​for an RS or RS resource. In some implementations, the RS resource indicator includes one or more SSB resource indicators (e.g., SSBRI) and / or one or more CSI-RS resource indicators (CRI). In some implementations, the quantized measurement values ​​include one or more L1-RSRP values ​​and / or one or more L1-SINR values.

[0198] In some implementations, the T-DU 174B also includes additional RS resource configurations in LTM DU configuration 1. Each additional RS resource configuration configures one or more additional RSs or one or more additional RS resources associated with cell 1. Additional RSs include SSBs and / or CSI-RSs. Additional RS resources include SSB resources and / or CSI-RS resources. In some implementations, each additional RS resource configuration includes an RS resource configuration ID. In some implementations, the additional RS resource configuration is (e.g., similar to) a CSI-ResourceConfig IE. In some implementations, the T-DU 174B includes a CSI-ResourceConfig IE in a CSI-MeasConfig IE. The T-DU 174B generates at least one additional reporting configuration for reporting measurement results of RSs or RS resources on cell 1 of the T-DU 174B and includes the additional reporting configuration in LTM DU configuration 1. In some implementations, the additional reporting configuration is (e.g., similar to) a CSI-ReportConfig IE.

[0199] In some implementations, the additional reporting configuration allows UE 102 to configure one or more UL resources (e.g., PUCCH or PUSCH resources) on cell 1 to transmit measurement results. In some implementations, each additional reporting configuration includes one or more RS resource configuration IDs identifying one or more RS resource configurations included in the additional RS resource configuration. After UE 102 performs an LTM serving cell change from cell 124A to cell 1, UE 102 communicates with S-DU 174B 436 and sends measurement results regarding the UL resources to S-DU 174B via cell 1 according to the additional reporting configuration. Accordingly, S-DU 174B receives measurement results regarding the UL resources from UE 102 via cell 1 according to the additional reporting configuration. In some implementations, each measurement result includes one or more RS resource indicators and / or one or more quantized measurement values. UE 102 performs measurements on the additional RS or additional RS resources according to the additional RS resource configuration and / or additional reporting configuration and obtains quantized measurement values ​​from the measurements. In some implementations, the RS resource indicator instructs UE 102 to perform measurements or obtain additional RS or RS resources for quantizing measurement values. In some implementations, the RS resource indicator includes one or more SSB resource indicators (SSBRI) and / or one or more CSI-RS resource indicators (CRI). In some implementations, the quantized measurement values ​​include one or more L1-RSRP values ​​and / or one or more L1-SINR values.

[0200] In some implementations, the T-DU 174B considers or generates RS resource configurations 2, ..., N and / or N+1, ..., N+M and / or report configurations 2, ..., N and / or N+1, ..., N+M based on RS resource configuration X, and includes RS resource configurations 2, ..., N and / or N+1, ..., N+M and / or report configurations 2, ..., N and / or N+1, ..., N+M in LTM DU configurations 2, ..., N and / or N+1, ..., N+M, as described above.

[0201] In other implementations, the LTM DU configuration X of procedure 380 includes at least one TCI state configuration X, where 1 ≤ X ≤ N. Each TCI state configuration X configures a TCI state that associates one or two DL RSs with the corresponding QCL type. In some implementations, the DL RS is associated with a cell X operated by S-DU 174A. In some implementations, each TCI state configuration X includes a TCI state ID. In some implementations, each TCI state configuration X is a TCI state IE. In some implementations, the TCI state configuration X includes / is an ul-TCI-ToAddModList-r17 field, one or more TCI-UL-State-r17 IEs, a dl-OrJointTCI-StateToAddModList-r17 field, one or more TCI-State IEs, a TCI-ActivatedConfig IE, and / or a tci-States ToAddModList field. In some implementations, LTM DU configuration X includes PDSCH-Config IE, and PDSCH-Config IE includes TCI state configuration X. In some implementations, T-DU 174B generates at least one TCI state configuration 1 considering or based on TCI state configuration X and includes TCI state configuration 1 in LTM DU configuration 1. In some implementations, TCI state configuration 1 includes TCI state configuration X. In other implementations, T-DU 174B includes each of TCI state configurations X in TCI state configuration 1, the difference being the TCI state ID in TCI state configuration X. T-DU 174B assigns a value to the TCI state ID for each TCI state configuration 1 (e.g., including TCI state configuration X) and includes the TCI state ID in the corresponding TCI state configuration. In some implementations, UE 102 and S-DU174B communicate with each other 436. S-DU 174B sends an LTM command to UE 102 to instruct UE 102 to perform a fast serving cell change to cell X. S-DU 174B includes a TCI state ID in the LTM command to instruct UE 102 to apply a TCI state configuration identified by the TCI state ID to communicate on cell X, where the TCI state configuration is one of TCI state configurations X, or a configuration that includes one of TCI state configurations X.

[0202] In a further implementation, the T-DU 174B considers or generates TCI state configurations 2, ..., N based on RS resource configuration X, and includes TCI state configurations 2, ..., N and / or N+1, ..., N+M in LTM DU configurations 2, ..., N and / or N+1, ..., N+M, as described above.

[0203] In some implementations, when CU 172 executes process 380 after executing process 490, CU 172 includes the LTM DU configuration 1, ..., N of process 490 in the CU to DU message of process 380, and S-DU 174A considers or generates the LTM DU configuration 1, ..., N of process 380 based on the configuration in the LTM DU configuration of process 490, in a manner similar to that described above.

[0204] In some implementations, CU 172 assigns IDs 1, ..., N to identify (e.g., received from T-DU 174B) LTM DU configurations 1, ..., N, and performs procedure 492 with T-DU 174B to provide IDs 1, ..., N and / or cell IDs 1, ..., N, similar to procedure 392. Therefore, T-DU 174B associates IDs 1, ..., N with LTM DU configurations 1, ..., N and / or cell IDs 1, ..., N, respectively. In other implementations, T-DU 174B assigns IDs 1, ..., N to identify (generated by T-DU 174B) LTM DU configurations 1, ..., N, and includes IDs 1, ..., N in the DU-to-CU message of procedure 490, similar to event 310. In some implementations, CU 172 assigns IDs N+1, ..., N+M to identify LTM DU configurations N+1, ..., N+M respectively, and performs a procedure (e.g., similar to procedure 492) with T-DU 174B to provide IDs N+1, ..., N+M and / or cell IDs N+1, ..., N+M, similar to procedure 392. Therefore, T-DU 174B associates IDs N+1, ..., N+M with LTM DU configurations N+1, ..., N+M and / or cell IDs N+1, ..., N+M respectively. In other implementations, T-DU 174B assigns IDs N+1, ..., N+M to identify LTM DU configurations N+1, ..., N+M respectively, and, similar to event 310, includes IDs 1, ..., N in the DU-to-CU message of the additional LTM preparation procedure.

[0205] In some implementations, CU 172 sends a CU-DU message 412, including IDs 1, ..., N, to S-DU 174A, and receives a DU-CU message 414 from S-DU 174A in response. The CU-DU message 412 and the DU-CU message 414 are... FIG. 4These are collectively referred to as LTM ID transmission procedure 493 or LTM cell index transmission procedure 493. In some implementations, messages 412 and 414 are the UE context modification request message and the UE context modification response message, respectively. In some implementations, CU 172 includes LTM DU configuration 1, ..., N and / or cell ID 1, ..., N in CU to DU message 412. In some implementations, CU 172 includes ID 1, ..., N in CU to DU message 412. In some implementations, CU 172 includes cell index 1, ..., N in CU to DU message 412. In a further implementation, CU 172 performs multiple LTM ID transmission procedures to send ID 1, ..., N, cell ID 1, ..., N and / or LTM DU configuration 1, ..., N to S-DU 174A. In each of the processes, CU 172 includes specific portions of ID 1, ..., N, cell ID 1, ..., N, and / or LTM DU configuration 1, ..., N in a CU-to-DU message similar to message 412. Therefore, S-DU 174A associates ID 1, ..., N with LTM DU configuration 1, ..., N, and / or cell ID 1, ..., N, respectively. In a further implementation, CU 172 performs multiple LTM cell index transmission processes to send cell index 1, ..., N, cell ID 1, ..., N, and / or LTM DU configuration 1, ..., N to S-DU 174A. In each of the processes, CU 172 includes specific portions of cell index 1, ..., N, cell ID 1, ..., N, and / or LTM DU configuration 1, ..., N in a CU-to-DU message similar to message 412. Therefore, S-DU 174A associates cell indices 1, ..., N with LTM DU configurations 1, ..., N and / or cell IDs 1, ..., N, respectively.

[0206] In some implementations, S-DU 174A generates a first service DU configuration based on LTM DU configurations 1, 2, ..., and / or N, and includes the first service DU configuration in the DU-to-CU message. In some implementations, the first service DU configuration includes a configuration that updates (e.g., enhances, modifies, or replaces) the service DU configuration. In other implementations, the first service DU configuration includes a configuration that is not included in the service DU configuration. CU 172 sends an RRC reconfiguration message including the first service DU configuration to UE 102. Upon receiving the RRC reconfiguration message, UE 102 applies the first service DU configuration to communicate with the service DU. For example, the RRC reconfiguration message is or is similar to the RRC reconfiguration message in procedure 494. In some implementations, UE 102 communicates with S-DU 174A using a configuration included in the service DU configuration that has not been updated by the first service DU configuration. The following are example implementations of generating the first service DU configuration based on LTM DU configurations 1, ..., N.

[0207] In some implementations, the LTM DU configuration Y of process 490 includes at least one RS resource configuration Y, where 1 ≤ Y ≤ N. Each RS resource configuration Y configures one or more RSs or one or more RS resources associated with cell Y of T-DU 174B. RSs include SSBs and / or CSI-RSs. RS resources include SSB resources and / or CSI-RS resources. In some implementations, each RS resource configuration Y includes an RS resource configuration ID. In some implementations, RS resource configuration Y is (e.g., similar to) CSI-ResourceConfig IE. In some implementations, LTM DU configuration Y includes CSI-MeasConfig IE, and CSI-MeasConfig IE includes CSI-ResourceConfig IE. S-DU 174A generates at least one service report configuration for reporting measurement results of RSs or RS resources on cell 124A and includes the service report configuration in the first service DU configuration. In some implementations, the service report configuration is (e.g., similar to) CSI-ReportConfig IE. In some implementations, S-DU 174A generates at least one service RS resource configuration considering or based on RS resource configuration Y, and includes the service RS resource configuration in a first service DU configuration. In some implementations, S-DU 174A includes RS resource configuration Y in the service RS resource configuration. In other implementations, S-DU 174A includes each of RS resource configurations Y in the service RS resource configuration, the difference being the RS resource configuration ID in RS resource configuration Y. S-DU 174A assigns a value to the RS resource configuration ID for each service RS resource configuration (e.g., including RS resource configuration Y), and includes the RS resource configuration ID in the corresponding service RS resource configuration.

[0208] In some implementations, the service report is configured for UE 102 to configure one or more UL resources (e.g., PUCCH or PUSCH resources) on cell 124A to transmit measurement results. In some implementations, each service report configuration includes one or more RS resource configuration IDs identifying one or more RS resource configurations included in the service RS resource configuration. When UE 102 communicates with S-DU 174A, UE 102 sends measurement results (e.g., event 424) regarding the UL resources to S-DU 174A via cell 124A according to the service report configuration. Accordingly, S-DU 174A receives the measurement results regarding the UL resources from UE 102 via cell 124A according to the service report configuration. In some implementations, each measurement result includes one or more RS resource indicators and / or one or more quantized measurement values. UE 102 performs measurements on the RS or RS resources according to the service RS resource configuration and / or service report configuration, and obtains quantized measurement values ​​from the measurements. In some implementations, the RS resource indicator instructs UE102 to perform a measurement or obtain a quantized measurement value from an RS or RS resource. In some implementations, the RS resource indicator includes one or more SSB resource indicators (SSBRI) and / or one or more CSI-RS resource indicators (CRI). In some implementations, the quantized measurement value includes one or more L1-RSRP values ​​and / or one or more L1-SINR values.

[0209] In other implementations, the LTM DU configuration Y of procedure 490 includes at least one TCI state configuration Y, where 1 ≤ Y ≤ N. Each TCI state configuration Y configures one or two DL RSs associated with a corresponding QCL type of TCI state. In some implementations, the DL RS is associated with a cell Y operated by T-DU 174B. In some implementations, each TCI state configuration Y includes a TCI state ID. In a further implementation, each of the TCI state configurations Y is a TCI state IE. In yet another implementation, the TCI state configuration Y includes / is an ul-TCI-ToAddModList-r17 field, one or more TCI-UL-State-r17 IEs, a dl-OrJointTCI-StateToAddModList-r17 field, one or more TCI-State IEs, a TCI-ActivatedConfig IE, and / or a tci-StatesToAddModList field. In some implementations, LTM DU configuration Y includes PDSCH-Config IE, and PDSCH-Config IE includes TCI state configuration Y. In some implementations, S-DU 174A generates at least one service TCI state configuration considering or based on TCI state configuration Y and includes the service TCI state configuration in the first service DU configuration. In some implementations, service TCI state configuration 1 includes TCI state configuration Y. In a further implementation, S-DU 174A includes each of TCI state configurations Y in the service TCI state configuration, differing only in the TCI state ID in TCI state configuration Y. S-DU 174A assigns a value to the TCI state ID for each service TCI state configuration (including TCI state configuration Y) and includes the TCI state ID in the corresponding service TCI state configuration. In some implementations, the S-DU 174A communicates with the UE 102 436, and the S-DU 174A sends an LTM command to the UE 102 to instruct the UE 102 to perform a fast serving cell change to cell Y. The S-DU 174A includes a TCI state ID in the LTM command to instruct the UE 102 to apply a TCI state configuration identified by the TCI state ID to communicate on cell Y, wherein the TCI state configuration is one of the TCI state configurations Y, or a configuration that includes one of the TCI state configurations Y.

[0210] In some implementations, CU 172 sends a CU-DU message including IDs N+1, ..., N+M to S-DU 174A, and receives a DU-CU message from S-DU 174A in response, similar to CU-DU message 412 and DU-CU message 414, respectively. In some implementations, CU 172 includes LTM DU configurations N+1, ..., N+M and / or cell IDs N+1, ..., N+M in the CU-DU message. In a further implementation, CU 172 performs multiple LTM ID transmission procedures to send IDs N+1, ..., N+M, cell IDs N+1, ..., N+M, and / or LTM DU configurations N+1, ..., N+M to S-DU 174A. In each step of the process, CU 172 includes specific portions of IDs N+1, ..., N+M; cell IDs N+1, ..., N+M; and / or LTM DU configurations 1, ..., N in a CU-to-DU message similar to message 412. Therefore, S-DU 174A associates IDs N+1, ..., N+M with LTM DU configurations N+1, ..., N+M and / or cell IDs N+1, ..., N+M, respectively. In some implementations, S-DU 174A generates a second service DU configuration based on LTM DU configurations N+1, N+2, ..., and / or N+M, and includes the second service DU configuration in the DU-to-CU message. In some implementations, the second service DU configuration includes configurations that are updated (e.g., enhanced, modified, or replaced) by 402 in the first service DU configuration and / or updated in the service DU configuration but not updated by the first service DU configuration. In a further implementation, the second service DU configuration includes configurations not included in the first service DU configuration. CU 172 sends an RRC reconfiguration message, including a second serving DU configuration, to UE 102 via S-DU 174A. Upon receiving the RRC reconfiguration message, UE 102 applies the second serving DU configuration to communicate with the serving DU. For example, the RRC reconfiguration message is or is similar to the RRC reconfiguration message in procedure 494. In some implementations, UE 102 communicates with S-DU 174A 402 using the configuration included in the serving DU configuration and / or a first serving DU configuration that has not been updated by the second serving DU configuration. In some implementations, S-DU 174A generates one or more new L1 measurement configurations based on the L1 measurement configurations in LTM DU configurations N+1, N+2, ..., and / or N+M, and includes the new L1 measurement configurations in the second serving DU configuration. In some implementations, the S-DU 174A generates one or more new TCI state configurations based on the TCI state configurations in LTM DU configurations N+1, N+2, ..., and / or N+M, and includes the new TCI state configurations in the second service DU configuration.

[0211] In some implementations, CU 172 and S-DU 174A execute a 380 procedure with UE 102, where the values ​​of ID1, ..., N in the procedure differ from the values ​​of ID1, ..., N and ID N+1, ..., N+M described for scenario 400. In some implementations, CU 172 and S-DU 174A execute a 380 procedure with UE 102, where the values ​​of cell ID1, ..., N in the procedure differ from the values ​​of cell ID1, ..., N and cell ID N+1, ..., N+M described for scenario 400. In some implementations, CU 172 and S-DU 174A execute a 380 procedure with UE 102, where the values ​​of cell index 1, ..., N in the procedure differ from the values ​​of cell index 1, ..., N and cell index N+1, ..., N+M described for scenario 400.

[0212] In some implementations, similar to event 324, UE 102 sends at least one measurement report 424 to S-DU 174A. The at least one measurement report (e.g., an L1 measurement report) includes an event ID, a first measurement result for cell 1 of T-DU 174B, and / or includes a second measurement result for cell 124A. In some implementations, the first measurement result may include RSRP, RSRQ, and / or SINR obtained by UE 102 from a reference signal transmitted on cell 1. In a further implementation, the second measurement result may include RSRP, RSRQ, and / or SINR obtained by UE 102 from a reference signal transmitted on cell 124A. In some implementations, the event ID, RSRP, RSRQ, and / or SINR are respectively L1 event ID, L1-RSRP, L1-RSRQ, and / or L1-SINR. In some implementations, based on the first measurement result and / or the second measurement result, S-DU 174A sends a first LTM command (i.e., LTM command 1) including ID 1 to UE 102, instructing UE 102 to perform a serving cell change to cell 1 of T-DU 174B. In some implementations, the first LTM command includes ID 1. In a further implementation, the first LTM command includes cell index 1. When UE 102 receives the first LTM command, UE 102 performs a serving cell change from serving cell to cell 1 according to LTM DU configuration 1. In some implementations, similar to event 332, after receiving the first LTM command (e.g., in response to this), UE 102 performs a random access procedure 432 with T-DU 174B. In some implementations, upon receiving the first LTM command or completing the 432 random access procedure (e.g., in response to this), similar to event 336, UE 102 communicates with T-DU 174B on the first cell using LTM DU configuration 1 and / or referencing LTM DU configuration 436, and communicates with CU 172 via T-DU 174B. In some implementations, when a serving cell change occurs in procedure 380, the serving cell is cell 1 or cell 2 of S-DU 174A. Otherwise, if no serving cell change occurs in procedure 380 or procedure 380 is not executed, the serving cell is cell 124A. If the first LTM command includes ID 1, UE 102 identifies LTM DU configuration 1 and / or cell ID 1 (i.e., cell 1) based on ID 1, as for FIG. 3 As stated above. If the first LTM command includes cell index 1, then UE 102 identifies LTM DU configuration 1, cell ID 1 (i.e., cell 1), and / or LTM ID 1 based on cell index 1, as for... FIG. 3As described above. Upon receiving the first LTM command or successfully accessing cell 1 (e.g., in response to this), UE 102 applies LTM DU configuration 1 to communicate with T-DU 174B.

[0213] In some implementations, upon determining that LTM DU Configuration 1 is activated or upon sending a 430 first LTM command, or in response to this, the S-DU 174A sends a 429 DU-to-CU message to the CU 172 instructing LTM execution. In some implementations, the S-DU 174A includes Cell ID 1 or ID 1 (i.e., LTM ID) in the 429 DU-to-CU message to indicate that the S-DU 174A intends to activate LTM DU Configuration 1 or trigger an LTM serving cell change. In a further implementation, the S-DU 174A sends the 429 DU-to-CU message to the CU 172 before or after sending the 430 LTM command. In some implementations, when or after the CU 172 receives the 429 DU-to-CU message, the CU 172 stops or suspends sending DL data for UE 102 to the S-DU 174A until it receives the 434 DU-to-CU message. After receiving the 434 DU to CU message, CU 172 starts, continues, or resumes sending DL data for UE 102 to T-DU 174B. When T-DU 174B detects UE 102 accessing cell 1 or later, T-DU 174B sends DL data to UE 102 via cell 1.

[0214] In some implementations, the resource release procedure 496 is similar to procedure 396. In some implementations, in the resource release procedure 496, CU 172 sends a CU-DU message (e.g., a UEContext Release Command message) to S-DU 174A to release the UE context of UE 102. In response, S-DU 174A releases the UE context of UE 102 and sends a 440 DU-CU message (e.g., a UE ContextRelease Complete message) to CU-172.

[0215] Events 380, 404, 406, 490, 492, 494, 494, 424, 426, 428, 429, 430, 431, 432, 434, 436, 496, 498, and 456 are in FIG. 4 This is collectively referred to as the LTM configuration and / or activation process 480.

[0216] Next reference FIG. 5AIn scenario 500A, base station 106 operates as the MN (Mean Access Provider) and base station 104 operates as the SN (Signal Provider). SN 104 includes CU 172 and DU 174. Scenario 500A is similar to scenario 300, except that scenario 500A is a DC (Distributed Data Center) scenario, while scenario 300 is a single-connectivity (SC) scenario. In some implementations, MN 106 includes components similar to... FIG. 3 The CU and DU of base station 104.

[0217] Initially, UE 102 communicates with MN 106 and SN 104 under DC. In event 502, UE 102 uses the serving DU configuration to communicate with DU 174 on cell 124A and uses the serving CU configuration to communicate with CU 172 via DU 174, similar to event 302. In some implementations, UE 102 does not communicate with CU 172 via DU 174 302. In some implementations, UE 102 under DC communicates with MN 106 and / or SN 104 via radio bearers 502 UL PDU and / or DL ​​PDU, which include SRB and / or DRB. In some implementations, MN 106 and / or SN 104 configure radio bearers for UE 102. UE 102 communicates a 502 UL PDU and / or DL ​​PDU to SN 104 on the SCG (i.e., SCG radio resource) configured for communication with UE 102 under DC. UE 102 communicates UL PDUs and / or DL ​​PDUs to MN 106 on the MCG (i.e., MCG radio resource) according to the MN configuration (i.e., MCG configuration) under DC. In some implementations, the serving DU configuration is the SN configuration (i.e., SCG configuration). In the MN configuration, MN 106 configures an MCG that includes at least one serving cell (e.g., cell 126 and / or other cells) operated by MN 106. In the serving DU configuration, SN 106A configures an SCG that includes at least one serving cell (e.g., cell 124A and / or other cells) operated by SN 104. In some implementations, the MN configuration includes multiple configuration parameters, and UE 102 receives configuration parameters from one or more RRC messages from MN 106. For example, regarding FIG. 3 The service DU configuration includes multiple configuration parameters. In some implementations, UE 102 receives these configuration parameters from SN 104, for example, via MN 106 and / or on an SRB (e.g., SRB3) configured to exchange RRC messages between UE 102 and SN 104.

[0218] In some implementations, when UE 102 communicates with MN 106 and SN 104 under DC, similar to procedures 380 and / or 480, MN 106 performs a 580 LTM DU configuration and / or activation procedure with UE 102. In some implementations, when communicating with MN 106 and SN 104 under DC, UE 102 sends at least one measurement report to CU 172 via DU 174 and cell 124A in events 504 and 506, respectively, similar to events 304 and 306. In a further implementation, when communicating with MN 106 and SN 104 under DC, UE 102 sends at least one measurement report 505 to MN 106 via cell 126. MN 106 then sends at least one measurement report 507 to CU 172. In some implementations, MN 106 generates at least one SN message including at least one measurement report and sends the at least one SN message to CU 172. In one implementation, the at least one SN message includes an RRC Transfer message and / or an SN Modification Request message.

[0219] Upon receiving at least one measurement report (e.g., in response to this) or during communication between SN 104 and UE 102, SN 104 determines to prepare a first cell for UE 102, as for... FIG. 3 As described. Events 590, 592, 594, 524, 526, 528, 529, 530, 531, 532, 534, 536, 596, 598, and 556 are similar to events 390, 392, 394, 324, 326, 328, 329, 330, 331, 332, 334, 336, 396, 398, and 356, respectively. After receiving the first LTM command 530, sending 531 to acknowledge or confirm that UE 102 has successfully connected to the first cell 532 or 536, similar to event 336, UE 102, operating under DC with MN 106 and SN 104, communicates 536 with DU 174 on the first cell according to LTM DU configuration 1, and communicates 536 with CU 172 via DU 174. In some implementations, similar to procedures 398 or 498, DU 174 and / or CU 172, together with UE 102, execute LTM execution procedure 598 to command UE 102 to perform a cell change from the first cell to the second cell. Due to procedure 598, similar to event 356, UE 102, operating under DC with MN 106 and SN 104, communicates 556 with DU 174 on the second cell according to LTM DU configuration 2, and also communicates 556 with CU 172 via DU 174.

[0220] Events 504, 506, 505, 507, 590, 592, 594, 524, 526, 528, 529, 530, 531, 532, 534, 536, 596, 598, and 556 are in FIG. 5A This is collectively referred to as the LTM DU configuration and / or activation process 581.

[0221] Next reference FIG. 5B Scenario 500B is generally similar to Scenario 500A, except that SN 104 sends RRC reconfiguration messages 517 and 519 to UE 102 via MN 106, and receives RRC reconfiguration completion messages 521 and 523 from UE 102 via MN 106. RRC reconfiguration messages 517 and 519 are similar to RRC reconfiguration messages 316 and 318. RRC reconfiguration completion messages 521 and 523 are similar to RRC reconfiguration messages 320 and 322. In some implementations, SN 104 generates a first SN message including the RRC reconfiguration message (e.g., an SN Modification Required message, an SN Modification Required message, or an RRC transmission message) and sends the first SN message 517 to MN 106. MN 106 generates an MN RRC message including the RRC reconfiguration message and sends the MN RRC message 519 to UE 102. In response, UE 102 generates an MN RRC response message including an RRC reconfiguration complete message and sends this MN RRC response message (521) to MN 106. In some implementations, MN 106 generates a second SN message (e.g., an SNReconfiguration Complete message or an RRC transmission message) including an RRC reconfiguration complete message and sends this second SN message (523) to SN 104. In some implementations, the MN RRC message and the MN RRC response message are respectively the RRC reconfiguration message and the RRC reconfiguration complete message.

[0222] Events 504, 506, 505, 507, 590, 592, 594, 517, 519, 521, 523, 524, 526, 528, 529, 530, 531, 532, 534, 536, 596, 598, and 556 are... FIG. 5B This is collectively referred to as the LTM DU configuration and / or activation process 582.

[0223] Next reference FIG. 6AIn scenario 600A, similar to scenarios 300 to 500B, base station 106 operates as the MN, and base station 104 operates as the SN. Similar to base station 104 in scenario 400, SN 104 includes CU 172, S-DU 174A, and T-DU 174B. In some implementations, when UE 102 communicates with MN 106 and SN 104 under DC, similar to procedures 380 and / or 480, MN 106 performs a 680 LTM DU configuration and / or activation procedure with UE 102. In some implementations, when UE 102 communicates with M-DU 174A and S-DU 174B under DC, similar to procedures 581 and / or 582, CU 172 performs a 681 LTM DU configuration and / or activation procedure with UE 102 via M-DU 174A or S-DU 174B.

[0224] Next reference FIG. 6B Scenario 600B is similar to scenarios 300-500B and 600A, except that SN 104 sends 617 and 619 RRC reconfiguration messages to UE 102 via MN 106, and receives 621 and 623 RRC reconfiguration complete messages from UE 102 via MN 106.

[0225] Next reference FIG. 7A In scenario 700A, base station 104 operates as both MN and SN, similar to scenarios 300-600B. Base station 104 includes CU 172, main DU (M-DU) 174A, and auxiliary DU (S-DU) 174B. CU 172 operates in conjunction with M-DU 174A, which acts as the MN, similar to... FIG. 3 Base station 104 or FIG. 5A to FIG. 6B MN 106, and CU 172 operate similarly to S-DU174B as SN. FIG. 5A to FIG. 6B SN 104 in the text.

[0226] In scenario 700A, UE 102 initially communicates with M-DU 174A and S-DU 174B under DC 702 and communicates with CU 172 via M-DU 174A and S-DU 174B 702. Similar to event 302, UE 102 uses the serving DU configuration to communicate with S-DU 174B on cell 124A 702 and uses the serving CU configuration to communicate with CU 172 via S-DU 174B 702. Events 704 and 706 are similar to events 304 and 306. In some implementations, similar to event 304, UE 102 sends 705 at least one measurement report to M-DU 174A. Similar to event 306, M-DU 174A then sends 707 at least one DU-to-CU message including at least one measurement report to CU 172 707. In some implementations, when UE 102 communicates with M-DU 174A and S-DU 174B under DC, similar to procedure 380, CU 172 performs the 780 LTM DU configuration and / or activation procedure with UE 102 via M-DU 174A.

[0227] Events 704, 706, 705, 707, 790, 792, 794, 724, 726, 728, 729, 730, 731, 732, 734, 736, 796, 798, and 756 are in FIG. 7A This is collectively referred to as the LTM configuration and / or activation process 781.

[0228] Next reference FIG. 7B Scenario 700B is similar to scenarios 300-600B and 700A, except that CU 172 sends 717 and 719 RRC reconfiguration messages to UE 102 via M-DU 174A and receives 721 and 723 RRC reconfiguration complete messages from UE 102 via M-DU 174A.

[0229] Events 704, 706, 705, 707, 790, 792, 794, 717, 719, 721, 723, 724, 726, 728, 729, 730, 731, 732, 734, 736, 796, 798, and 756 are in FIG. 7B This is collectively referred to as the LTM DU configuration and / or activation process 782.

[0230] Next reference FIG. 8AIn scenario 800A, base station 104 operates as both MN and SN, similar to scenarios 300-700B. Base station 104 includes CU 172, primary DU (M-DU) 174A, secondary DU (S-DU) 174B, and target secondary DU (T-DU) 174C. CU 172 operates with M-DU 174A as MN and with S-DU 174B as SN. In some implementations, when UE 102 communicates with M-DU 174A and S-DU 174B under DC, similar to procedure 380, CU 172 performs the 880 LTM DU configuration and / or activation procedure with UE 102 via M-DU 174A. In a further implementation, when UE 102 communicates with M-DU 174A and S-DU 174B under DC, CU 172 performs an LTM DU configuration and / or activation procedure similar to procedure 581 or 582 together with UE 102 via S-DU 174A.

[0231] Next reference FIG. 8B Scenario 800B is similar to scenarios 300-700B and 800A, except that CU 172 sends RRC reconfiguration messages 817 and 819 to UE 102 via M-DU 174A, and receives RRC reconfiguration completion messages 821 and 823 from UE 102 via M-DU 174A.

[0232] In some implementations, the RAN node (such as a base station, DU, or CU) or the UE performs early timing advance (TA) acquisition for LTM, as detailed below. FIG. 9A Let's discuss this further in Figure 14. FIG. 3 to FIG. 8B At least some of the discussions in [the original text] also apply to [the following text]. FIG. 9A See Figure 14.

[0233] FIG. 9A The UE (e.g.) was demonstrated FIG. 3 to FIG. 8B UE 102 in the RAN can be implemented to communicate with the RAN (e.g., FIG. 3 to FIG. 8B Example method 900A for processing early TA acquisition (RAN 105 or base stations 104 and 106).

[0234] Method 900A begins at block 902, where the UE communicates with the RAN via the serving cell (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, 780, 880, and 881). At block 909, while communicating with the RAN via the serving cell, the UE starts a first time alignment timer for uplink synchronization with the serving cell. At block 918, the UE receives LTM configuration from the RAN, where the LTM configuration configures the first cell (e.g., events 316, 318, 394, 380, 494, 480, 580, 594, 581, 582, 680, 694, 617, 619, 780, 794, 880, 881, 894, 817, and 819). The first cell is the target cell or candidate cell for LTM. In box 925, the UE receives a first command from the RAN via the serving cell, wherein the first command instructs the UE to send a random access preamble on the first cell.

[0235] At block 927, in response to the first command, the UE sends a first random access preamble to the RAN on the first cell. At block 930A, the UE receives an LTM command from the RAN via the serving cell, wherein the LTM command instructs the UE to connect to the first cell and includes TA values ​​(e.g., events 330, 350, 398, 380, 430, 450, 498, 480, 580, 530, 598, 581, 582, 680, 681, 630, 698, 780, 730, 798, 880, 881, 830, and 898). At block 941, the UE resets the MAC entity in response to receiving the LTM command. In some implementations, at block 902, the UE uses the MAC entity to communicate with the RAN. At box 932, the UE accesses the first cell in response to receiving an LTM command (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). At box 947, the UE starts a second time alignment timer for uplink synchronization with the first cell. At box 936, the UE uses the TA value and LTM configuration to communicate with the RAN on the first cell (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, and 881).

[0236] In some implementations, the UE receives the first command while the first time alignment timer is running. In other implementations, the UE receives the first command before the first time alignment timer is running. In some implementations, the UE disconnects from the serving cell upon receiving the LTM command. In a further implementation, the UE disconnects from the serving cell after successfully accessing the first cell. In some implementations, when the UE successfully accesses the first cell, the UE identifies the first cell as the new serving cell.

[0237] In some implementations, the UE starts a second time alignment timer upon receiving an LTM command (e.g., in response to this). In some implementations, the UE starts the second time alignment timer after resetting the MAC entity. In a further implementation, the UE starts the second time alignment timer before resetting the MAC entity. In such cases, when the MAC entity is reset, the UE avoids stopping the second time alignment timer and / or avoids determining that the second time alignment timer has expired. In some implementations, in response to resetting the MAC entity, the UE stops the first time alignment timer and determines that the first time alignment timer has expired.

[0238] In some implementations, at block 902, the UE starts a MAC timer associated with a MAC entity for communicating with the RAN via the serving cell. The UE stops the MAC timer in response to resetting the MAC entity. In some implementations, the MAC timer includes a timer for performing discontinuous reception (DRX) with the RAN on the serving cell. In some implementations, the MAC timer includes one or more timers for performing HARQ operations with the RAN on the serving cell.

[0239] In some implementations, the RAN obtains the TA values ​​of the UE and the first cell based on the time when the RAN receives the first random access preamble. In other implementations, after sending the first random access preamble, the UE continues to communicate with the RAN via the serving cell until it receives the LTM command.

[0240] In some implementations, the LTM configuration includes the LTM DU configuration for the first cell as described above. In some implementations, the RAN includes the LTM DU configuration in an RRC message (e.g., an RRC reconfiguration message) and also includes the RRC message in the LTM configuration. In some implementations, the RAN includes the LTM CU configuration in the RRC message. Both the LTM CU and LTM DU configurations include the configurations described above. In some implementations, the LTM configuration is an LTM-Candidate IE or an LTM-CandidateToAddMod IE. In other implementations, the LTM configuration is an LTM-Config IE.

[0241] In some implementations, the first command includes configuration parameters such as a first random access preamble index, an indicator indicating a UL or supplementary UL (SUL), an SSB index, and / or a physical random access channel (PRACH) mask index. The first random access preamble index indicates, identifies, or indexes the first random access preamble. Therefore, the UE generates or selects the first random access preamble based on the first random access preamble index. In some implementations, the PRACH mask index configures one or more PRACH timings. The UE determines the PRACH timing based on the SSB index and / or the PRACH mask index to transmit the first random access preamble. In some implementations, an indicator set to 0 indicates a UL, and an indicator set to 1 indicates a SUL. The UE transmits the first random access preamble on the UL or SUL of the first cell based on the indicator. In some implementations, the first command includes a DCI format identifier and / or a frequency domain resource allocation field. In some implementations, the DCI format identifier is set to zero for both the first and second formats. In some implementations, all bits in the frequency domain resource allocation field are set to zero.

[0242] In some implementations, the LTM configuration includes random access configuration parameters. In some implementations, the random access configuration parameters include a PRACH root sequence index and / or a PRACH subcarrier spacing. In some implementations, the UE uses the PRACH root sequence index and a first random access preamble index to generate or select a first random access preamble. In some implementations, the LTM configuration includes a random access channel (RACH) configuration, which includes random access configuration parameters. The UE uses 1) the random access configuration parameters and 2) an indicator (e.g., indicating UL or SUL), an SSB index, and / or a PRACH mask index to transmit the first random access preamble on the first cell.

[0243] In some implementations, the LTM configuration includes the cell ID (e.g., PCI) of a first cell. In some implementations, the first command includes a (new) field indicating the cell in which a random access preamble (e.g., a first random access preamble) is transmitted (to be transmitted). In some implementations, the new field includes the cell ID of the first cell. Based on the cell ID included in the first command, the UE determines that the first cell is the cell in which the UE wants to transmit the first random access preamble. The UE identifies the LTM configuration based on the cell ID. In other implementations, the LTM configuration includes a cell index of the first cell, and a new field includes the cell index. The cell index is not the cell ID, and the size of the cell index is smaller than the size of the cell ID. The UE identifies the LTM configuration based on the cell index. Based on the cell ID included in the LTM configuration, the UE determines that the first cell is the cell in which the UE wants to transmit the first random access preamble. In a further implementation, a new field includes an LTM ID identifying the LTM configuration, and the UE identifies the LTM configuration based on the LTM ID. The UE receives the LTM ID along with the LTM configuration as described above. Based on the cell ID included in the LTM configuration, the UE determines that the first cell is the cell in which the UE will send the first random access preamble.

[0244] In some implementations, the UE receives additional LTM configurations from the RAN, and each of these additional LTM configurations represents a cell and includes a cell ID identifying that cell, as shown in the figure. In some implementations, each of these additional LTM configurations represents a cell and includes a cell index indicating that cell, as shown in the figure. FIG. 3 to FIG. 8B As described. In some implementations, each of these other LTM configurations is a cell and associated with an LTM ID, such as for... FIG. 3 to FIG. 8B As described.

[0245] In some implementations, the first command is a DCI or PDCCH command. The UE receives the first command on the PDCCH from the RAN via the serving cell. In other implementations, the first command is a MAC CE. The UE receives a MAC PDU including the first command from the RAN via the serving cell.

[0246] In some implementations, the RAN sets the frequency domain resource allocation field to a specific value (e.g., a non-zero value) to indicate that the first command includes a new field indicating the cell. The RAN sets all bits in the frequency domain resource allocation field to zero to indicate that the second command does not include a new field indicating the cell. In other implementations, the RAN sets the frequency domain resource allocation field to zero in both the first and second commands.

[0247] In some implementations, the UE uses 1) the random access configuration parameters included in the LTM configuration and / or 2) the configuration parameters included in the first command to send a first random access preamble to the RAN on the first cell.

[0248] In some implementations, in addition to LTM configuration, the UE also receives RACH configuration from the RAN. In some implementations, the UE receives RRC messages from the RAN that include both RACH and LTM configurations (e.g., events 316, 318, 394, 380, 494, 480, 580, 594, 581, 582, 680, 694, 617, 619, 780, 794, 880, 881, 894, 817, and 819). The RACH configuration sets random access configuration parameters for the first cell for early TA acquisition. In such cases, the UE uses 1) the random access configuration parameters included in the RACH configuration instead of the LTM configuration, and / or 2) the configuration parameters included in the first command to send a first random access preamble to the RAN on the first cell.

[0249] In some implementations, the RACH configuration includes the cell ID (e.g., PCI) of the first cell. In some implementations, the first command includes a (new) field indicating the cell in which a random access preamble (e.g., the first random access preamble) is transmitted (e.g., to be transmitted). In some implementations, the new field includes the cell ID of the first cell. Based on the cell ID included in the first command, the UE determines that the first cell is the cell in which the UE wants to transmit the first random access preamble. The UE identifies the RACH configuration based on the cell ID. In other implementations, the RACH configuration includes the cell index of the first cell, and the new field includes the cell index. The cell index is not the cell ID, and the size of the cell index is smaller than the size of the cell ID. The UE identifies the RACH configuration based on the cell index. Based on the cell ID included in the RACH configuration, the UE determines that the first cell is the cell in which the UE wants to transmit the first random access preamble. In a further implementation, the new field includes an LTM ID identifying the LTM configuration and the RACH configuration, and the UE identifies the RACH configuration based on the LTM ID. The UE receives the LTM ID along with the LTM configuration and RACH configuration as described above. Based on the cell ID included in the LTM configuration or RACH configuration, the UE determines the first cell as the cell in which the UE transmits the first random access preamble. In some implementations, the UE receives other RACH configurations from the RAN. In some implementations, each of the other RACH configurations includes random access configuration parameters for the cell used for early TA acquisition. In a further implementation, each of the other RACH configurations includes a cell ID identifying the cell. In yet another implementation, each of the other RACH configurations includes a cell index indicating the cell. In some implementations, each of the other RACH configurations is associated with an LTM ID, as described above.

[0250] In some implementations, at block 902, the UE transmits multiple UE capabilities to the RAN via the serving cell. In a further implementation, the UE transmits multiple UE capabilities to the RAN via another serving cell. In some implementations, the multiple UE capabilities include a first UE capability indicating support for LTM. In a further implementation, the multiple UE capabilities include a second UE capability indicating support for early TA acquisition. In some implementations, the UE receives an early TA acquisition configuration from the RAN to enable or configure early TA acquisition. The UE enables early TA acquisition in response to receiving the early TA acquisition configuration. When early TA acquisition is enabled, the UE attempts to receive a command (e.g., a first command) from the RAN via the serving cell, which instructs the UE to transmit a random access preamble on the target cell or candidate cell. If the UE does not receive the early TA acquisition configuration, the UE avoids attempting to receive the command (e.g., the first command), which instructs the UE to transmit a random access preamble on the target cell or candidate cell.

[0251] In some implementations, the UE starts a first time alignment timer using a first timer value and starts a second time alignment timer using a second timer value. In some implementations, the first timer value and the second timer value may be the same or different. In some implementations, the UE receives a System Information Block (SIB) (e.g., SIB1) including the first timer value from the RAN on the serving cell. In further implementations, the UE receives an RRC message (e.g., RRC establishment message, RRC recovery message, or RRC reconfiguration message) including the first timer value from the RAN via the serving cell or another serving cell. In some implementations, the LTM configuration includes the second timer value.

[0252] In some implementations, when communicating with the RAN on the serving cell, the UE receives a TA command from the RAN on the serving cell, including a new TA value. The UE adjusts its uplink transmission timing with the serving cell based on the new TA value and restarts a first time alignment timer in response to receiving the TA command. In some implementations, the TA command is a MAC CE. In some implementations, when communicating with the RAN on the first cell at block 936, the UE receives a TA command from the RAN on the first cell, including a new TA value. The UE adjusts its uplink transmission timing with the first cell based on the new TA value and restarts a second time alignment timer in response to receiving the TA command.

[0253] FIG. 9B This is a flowchart of an example method 900B, similar to method 900A, except that method 900B includes block 953 instead of block 947. At block 953, the UE starts or restarts a first time alignment timer for uplink synchronization with the first cell.

[0254] FIG. 9C This is a flowchart of an example method 900C, similar to methods 900A and 900B, except that method 900C includes blocks 930C, 933, 957, 959, 947, and 953 instead of block 930A. At block 930C, the UE receives an LTM command from the RAN via the serving cell, where the LTM command instructs the UE to connect to the first cell. At block 933, the UE determines whether the LTM command includes a TA value. If the UE determines at block 933 that the LTM command includes a TA value, the procedure continues to block 932. The procedure then continues from block 932 to block 947 or block 953. Otherwise, if the UE determines at block 933 that the LTM command does not include a TA value, the procedure continues to block 957. At box 957, the UE performs a random access procedure with the RAN on the first cell (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). At box 959, during the random access procedure, the UE receives a random access response including a TA value from the RAN on the first cell (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). The procedure continues from box 959 to box 947 or 953. At box 947, upon receiving a random access response (e.g., in response to this), the UE starts a second time alignment timer for uplink synchronization with the first cell. At box 953, upon receiving a random access response (e.g., in response to this), the UE starts or restarts a first time alignment timer for uplink synchronization with the first cell. The procedure continues from boxes 947, 953, 947, and 953 to box 936.

[0255] In some implementations, at block 947, the UE stops the first time alignment timer after a random access response (e.g., in response to this). In other implementations, at block 947, the UE keeps the first time alignment timer running. In some implementations, when the first time alignment timer expires while the second time alignment timer is running, the UE communicates with the RAN on the first cell and ignores the expiration of the first time alignment timer. In other words, in such cases, the UE does not respond to the expiration of the first time alignment timer.

[0256] FIG. 10A The RAN (e.g.) was shown. FIG. 3 to FIG. 8BRAN 105, or base stations 104, 106, or DU 174, 174A, 174B, or 174C) manage the UE (e.g., FIG. 3 to FIG. 8B Example method 1000A for early TA acquisition in UE 102).

[0257] Method 1000A begins at block 1002, where the RAN communicates with the UE via the serving cell (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, 780, 880, and 881). At block 1009, while communicating with the UE via the serving cell, the RAN starts a first time alignment timer for uplink synchronization with the UE. At block 1018, the RAN sends an LTM configuration to the UE, where the LTM configuration configures the first cell (e.g., events 316, 318, 394, 380, 494, 480, 580, 594, 581, 582, 680, 694, 617, 619, 780, 794, 880, 881, 894, 817, and 819). At block 1025, the RAN sends a first command to the UE via the serving cell, wherein the first command instructs the UE to send a first random access preamble on the first cell. At block 1027, the RAN receives the first random access preamble from the UE on the first cell. At block 1030A, the RAN sends an LTM command to the UE via the serving cell, wherein the LTM command instructs the UE to connect to the first cell and includes TA values ​​(e.g., events 330, 350, 398, 380, 430, 450, 498, 480, 580, 530, 598, 581, 582, 680, 681, 630, 698, 780, 730, 798, 880, 881, 830, and 898). At block 1041, the RAN resets the MAC entity in response to sending the LTM command. In some implementations, at block 1002, the RAN uses the MAC entity (i.e., the first MAC entity) to communicate with the UE. In some implementations, at block 1002, the RAN uses another MAC entity (i.e., a second MAC entity) to communicate with the UE. In a further implementation, the RAN resets the MAC entity in response to preparing the first cell for LTM instead of sending an LTM command. At block 1032, the RAN detects UE access to the first cell after sending an LTM command (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). At block 1047, the RAN starts a second time alignment timer for uplink synchronization with the UE on the first cell.At box 1036, the RAN uses the TA value to communicate with the UE on the first cell while maintaining the operation of the second time alignment timer (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, and 881).

[0258] In some implementations, the RAN obtains (e.g., calculates or derives) the TA value for uplink synchronization with the UE in the first cell based on the time the RAN receives the first random access preamble. In some implementations, after receiving the first random access preamble, the RAN continues to communicate with the UE via the serving cell until an LTM command is sent.

[0259] In some implementations, the RAN starts a second time alignment timer after receiving the first random access preamble or obtaining the TA value for the UE (e.g., in response to this). In a further implementation, the RAN starts the second time alignment timer after sending an LTM command. In some implementations, the RAN starts the second time alignment timer after resetting the MAC entity. In a further implementation, the RAN starts the second time alignment timer before resetting the MAC entity. In such cases, when the MAC entity is reset, the RAN avoids stopping the second time alignment timer and / or avoids determining that the second time alignment timer has expired. In some implementations, in response to resetting the MAC entity, the RAN stops the first time alignment timer and determines that the first time alignment timer has expired.

[0260] In some implementations, at block 1002, the RAN starts a MAC timer associated with the MAC entity for communicating with the UE via the serving cell. The RAN stops the MAC timer in response to resetting the MAC entity. In some implementations, the MAC timer includes a timer for DRX operation with the RAN on the serving cell. In some implementations, the MAC timer includes one or more timers for HARQ operation with the UE on the serving cell.

[0261] In some implementations, the RAN uses 1) the random access configuration parameters included in the LTM configuration and / or 2) the configuration parameters included in the first command to receive the first random access preamble from the UE on the first cell. In some implementations, in addition to the LTM configuration, the RAN also sends a RACH configuration to the UE. For example, the RAN sends an RRC message to the UE that includes both the RACH configuration and the LTM configuration (e.g., events 316, 318, 394, 380, 494, 480, 580, 594, 581, 582, 680, 694, 617, 619, 780, 794, 880, 881, 894, 817, and 819). The RACH configuration configures the random access configuration parameters for the first cell for early TA acquisition. In such cases, the RAN uses 1) the random access configuration parameters included in the RACH configuration and / or 2) the configuration parameters included in the first command to receive the first random access preamble from the UE on the first cell.

[0262] In some implementations, at block 1002, the RAN receives multiple UE capabilities from the UE via the serving cell. In a further implementation, the RAN receives multiple UE capabilities from the UE via another serving cell. In yet another implementation, the RAN receives multiple UE capabilities from a CN (e.g., CN 110 or AMF 164). In some implementations, the multiple UE capabilities include a first UE capability indicating support for LTM. The RAN sends an LTM configuration to the UE in response to receiving the first UE capability. In some implementations, the multiple UE capabilities include a second UE capability indicating support for early TA acquisition. In some implementations, the RAN sends an early TA acquisition configuration to the UE to enable or configure early TA acquisition. When early TA acquisition of the UE is enabled, the RAN sends a command (e.g., a first command) to the UE via the serving cell, which instructs the UE to send a random access preamble on a target cell or candidate cell.

[0263] In some implementations, when communicating with the UE on the serving cell, the RAN sends a TA command including a new TA value to the UE on the serving cell to adjust the uplink transmission timing between the UE and the serving cell. The RAN restarts a first time alignment timer in response to sending the TA command. In some implementations, the TA command is a MAC CE. In some implementations, when communicating with the UE on the first cell at block 1036, the RAN sends a TA command including a new TA value to the UE on the first cell to adjust the uplink transmission timing between the UE and the first cell. The RAN restarts a second time alignment timer in response to sending the TA command.

[0264] In some implementations, the RAN sends the first command while the first time alignment timer is running. In a further implementation, the RAN sends the first command when the first time alignment timer is not running.

[0265] FIG. 10B This is a flowchart of an example method 1000B, similar to method 1000A, except that method 1000B includes block 1053 instead of block 1047. At block 1053, in response to sending an LTM command, the RAN starts or restarts a first-time network alignment timer for uplink synchronization with the UE on the first cell.

[0266] FIG. 10C This is a flowchart of an example method 1000C, similar to methods 1000A and 1000B, except that method 1000C includes blocks 1030C, 1033, 1057, 1059, 1047, 1053, and 1036 instead of block 1030A. At block 1013, the RAN sends an LTM command to the UE via the serving cell, where the LTM command instructs the UE to connect to the first cell. At block 1033, the RAN determines whether the LTM command includes a TA value. If the RAN determines at block 1033 that the LTM command includes a TA value, the procedure continues to block 1032. The procedure then continues from block 1032 to block 1047 or block 1053. Otherwise, if the RAN determines at block 1033 that the LTM command does not include a TA value, the procedure continues to block 1057. At box 1057, the RAN performs a random access procedure with the UE on the first cell (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). The procedure continues from box 1059 to box 1047 or box 1053. At box 1059, the RAN sends a random access response, including the TA value, to the UE on the first cell during the random access procedure. At box 1053, after sending the random access response or obtaining the TA value (e.g., in response here), the RAN starts or restarts a first time alignment timer for uplink synchronization with the UE on the first cell. At box 1047, after the RAN sends a random access response or obtains a TA value (e.g., in response to this), it starts a second time alignment timer for uplink synchronization with the UE on the first cell. The flow proceeds from boxes 1047, 1053, 1047 and / or 1053 to box 1036.

[0267] FIG. 9A to FIG. 9C At least part of the discussion is applicable FIG. 10A to FIG. 10C .

[0268] FIG. 11A The UE (e.g.) was demonstrated FIG. 3 to FIG. 8B UE 102) and RAN (e.g., FIG. 3 to FIG. 8B Example method 1100A for processing early TA acquisition (RAN105, or base station 104 and base station 106).

[0269] Method 1100A begins at block 1102, where the UE communicates with the RAN via the serving cell (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, 780, 880, and 881). At block 1109, while communicating with the RAN via the serving cell, the UE starts a first time alignment timer for uplink synchronization with the serving cell. At block 1118, the UE receives LTM configuration from the RAN, where the LTM configuration configures the first cell (e.g., events 316, 318, 394, 380, 494, 480, 580, 594, 581, 582, 680, 694, 617, 619, 780, 794, 880, 881, 894, 817, and 819). At block 1125, the UE receives a first command from the RAN via the serving cell, wherein the first command instructs the UE to send a first random access preamble on the first cell. At block 1127, in response to the first command, the UE sends the first random access preamble to the RAN on the first cell. At block 1159, in response to the first random access preamble, the UE receives a random access response, including a TA value, from the RAN on the serving cell or the first cell. At block 1147, in response to receiving the random access response, the UE starts a second time alignment timer for uplink synchronization with the first cell. In some implementations, in response to receiving the random access response, the UE maintains the first time alignment timer running. In a further implementation, in response to receiving the random access response, the UE avoids stopping the first time alignment timer. At block 1130, after receiving the random access response message, the UE receives an LTM command from the RAN via the serving cell, wherein the LTM command instructs the UE to connect to the first cell. At block 1141, in response to receiving the LTM command, the UE resets the MAC entity and maintains the second time alignment timer running while resetting the MAC entity. In block 1116, the UE accesses the first cell in response to receiving an LTM command. In block 1136, the UE communicates with the RAN on the first cell using the TA value, while maintaining the operation of the second time alignment timer.

[0270] FIG. 11A and FIG. 9A Broadly similar, and for FIG. 9A The discussion can be applied to FIG. 11AThe differences will be discussed where appropriate below. The LTM command in box 1130 does not include the TA value, while the LTM command in box 930A does. The RAN will not respond to FIG. 9A The UE sends a random access response to the UE in response to receiving the first random access preamble. In block 1147, the UE starts a second time alignment timer in response to receiving the random access response, and in block 947, the UE starts a second time alignment timer in response to receiving an LTM command.

[0271] FIG. 11B This is a flowchart of an example method 1100B, similar to method 1100A, except that method 1100B includes blocks 1171, 1157, 1159, 1147, and 1153. At block 1171, the UE determines whether the LTM command instructs the application of a TA value. If the UE determines at block 1171 that the LTM command instructs the application of a TA value, the process continues to blocks 1170 and 1116. Otherwise, if the UE determines at block 1171 that the LTM command instructs not to apply a TA value, the process continues to block 1157. At box 1157, the UE performs a random access procedure with the RAN on the first cell (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). At box 1159, the UE receives a random access response, including a TA value, from the RAN on the first cell during the random access procedure. The process continues from box 1159 to box 1147 or box 1153. At box 1147, the UE starts a second time alignment timer for uplink synchronization with the RAN on the first cell. At box 1153, the UE starts or restarts a first time alignment timer for uplink synchronization with the RAN on the first cell. The process continues from boxes 1147, 1153 and / or 1116 to box 1136.

[0272] In some implementations, at block 1147, the UE stops the first time alignment timer after a random access response (e.g., in response to this). In further implementations, at block 1147, the UE maintains or avoids stopping the first time alignment timer after a random access response (e.g., in response to this). In some implementations, when the first time alignment timer expires while a second time alignment timer is running, the UE communicates with the RAN on the first cell and ignores the expiration of the first time alignment timer. In other words, in such cases, the UE does not respond to the expiration of the first time alignment timer.

[0273] In some implementations, the LTM command in block 1130 includes a first indication instructing the UE to apply the TA value received in the random access response. In a further implementation, the LTM command in block 1130 includes a second indication instructing the UE not to apply the TA value received in the random access response. In yet another implementation, the LTM command excludes the first indication used to instruct the UE not to apply the TA value received in the random access response. In still another implementation, the LTM command excludes the second indication used to instruct the UE to apply the TA value received in the random access response.

[0274] FIG. 11B and FIG. 9B Broadly similar, and for FIG. 9B The discussion also applies to FIG. 11B .

[0275] FIG. 12A The RAN (e.g.) was shown. FIG. 3 to FIG. 8B Example method 1200A for early TA acquisition of UE (e.g., UE 102) managed by RAN 105, or base station 104, 106 or DU 174, 174A, and 174B or 174C.

[0276] Method 1200A begins at block 1202, where the RAN communicates with the UE via the serving cell (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, 780, 880, and 881). At block 1209, while communicating with the UE via the serving cell, the RAN starts a first time alignment timer for uplink synchronization with the UE. At block 1218, the RAN sends an LTM configuration to the UE, where the LTM configuration configures the first cell (e.g., events 316, 318, 394, 380, 494, 480, 580, 594, 581, 582, 680, 694, 617, 619, 780, 794, 880, 881, 894, 817, and 819). At block 1225, the RAN sends a first command to the UE via the serving cell, wherein the first command instructs the UE to send a first random access preamble on the first cell. At block 1227, after sending the first command, the RAN receives the first random access preamble from the UE on the first cell. At block 1259, in response to receiving the first random access preamble, the RAN sends a random access response to the UE on the serving cell or the first cell. At block 1247, the RAN starts a second time alignment timer for uplink synchronization with the UE on the first cell. At box 1230, after sending a random access response, the RAN sends an LTM command to the UE via the serving cell, whereby the LTM command instructs the UE to connect to the first cell (e.g., events 330, 350, 398, 380, 430, 450, 498, 480, 580, 530, 598, 581, 582, 680, 681, 630, 698, 780, 730, 798, 880, 881, 830, and 898). At box 1241, the RAN resets the MAC entity in response to sending the LTM command. At box 1270, when the MAC entity is reset, the RAN maintains the operation of the second time alignment timer. At box 1232, the RAN detects that the UE has accessed the first cell after sending the LTM command (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). At box 1236, the RAN communicates with the UE on the first cell using the TA value while maintaining the operation of the second time alignment timer (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, and 881).

[0277] FIG. 10A and FIG. 10A Broadly similar, and for FIG. 12A The discussion can be applied to FIG. 10A The differences will be discussed where appropriate below. The LTM command in box 1230 does not include the TA value, while the LTM command in box 1030A does. The RAN will not respond to... FIG. 11A The RAN sends a random access response to the UE in response to the first random access preamble. In block 1247, the RAN starts a second time alignment timer in response to sending the random access response, and in block 1047, the RAN starts a second time alignment timer in response to sending an LTM command. FIG. 12A The discussion also applies to FIG. 12B .

[0278] FIG. 12B This is a flowchart of an example method 1200B, similar to method 1200A, except that method 1200B includes blocks 1271, 1257, 1259, 1247, and 1253. At block 1271, the RAN determines whether the LTM command instructs the application of a TA value. If the RAN determines at block 1271 that the LTM command instructs the application of a TA value, the process continues to blocks 1270 and 1232. Otherwise, if the RAN determines at block 1271 that the LTM command instructs that a TA value should not be applied, the process continues to block 1257. At box 1257, the RAN performs a random access procedure with the UE on the first cell (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). At box 1259, during the random access procedure, the RAN sends a random access response including the TA value to the UE on the first cell (e.g., events 332, 352, 398, 380, 432, 452, 498, 480, 580, 532, 598, 581, 582, 680, 632, 698, 681, 780, 732, 798, 880, 881, 832, and 898). The procedure continues from box 1259 to box 1247 or box 1253. At box 1247, the RAN starts a second time alignment timer for uplink synchronization with the UE on the first cell. At box 1253, the RAN starts or restarts a first time alignment timer for uplink synchronization with the UE on the first cell. The procedure continues from boxes 1247, 1253, and / or 1232 to box 1236.

[0279] In some implementations, at block 1247, the RAN stops the first time alignment timer after a random access response (e.g., in response to this). In other implementations, at block 1247, the RAN maintains or avoids stopping the first time alignment timer after a random access response (e.g., in response to this). In some implementations, when the first time alignment timer expires while the second time alignment timer is running, the RAN communicates with the UE on the first cell and ignores the expiration of the first time alignment timer. In other words, in such cases, the RAN does not respond to the expiration of the first time alignment timer.

[0280] FIG. 10B and FIG. 10B Broadly similar, and for FIG. 12B The discussion also applies to FIG. 11B .right FIG. 13 The discussion also applies to FIG. 3 to FIG. 8B .

[0281] FIG. 3 to FIG. 8B The UE (e.g.) was demonstrated FIG. 14A UE 102) and RAN (e.g., FIG. 3 to FIG. 8B Example method 1300 for handling uplink synchronization time alignment timers in RAN105 or base stations 104, 106.

[0282] Method 1300 begins at block 1301, where the UE performs the actions described in blocks 1102, 1109, 1118, 1125, 1127, 1159, and 1147. At block 1372, while the first time alignment timer is running, the UE detects that the second time alignment has expired. At block 1374, in response to this detection, the UE keeps the first time alignment timer running.

[0283] FIG. 3 to FIG. 8B The UE (e.g.) was demonstrated FIG. 14B UE 102) and RAN (e.g., FIG. 9A to FIG. 9C Example method 1400A for handling uplink synchronization time alignment timers in RAN105 or base stations 104, 106.

[0284] Method 1400A begins at block 1401, where the UE performs the actions described in blocks 1102, 1109, 1118, 1125, 1127, 1159, and 1147. At block 1473, while the second time alignment timer is running, the UE detects that the first time alignment has expired. At block 1475, in response to this detection, the UE keeps the second time alignment timer running.

[0285] FIG. 11A to FIG. 11BThis is a flowchart of an example method 1400B, similar to method 1400A, except that method 1400B includes block 1476 instead of block 1406. At block 1476, the UE stops the second time alignment timer in response to the detection.

[0286] right FIG. 13 and FIG. 14A The discussion can be applied to FIG. 14B , FIG. 13 and FIG. 14A Similarly, for FIG. 14B , FIG. 9A to FIG. 9C and FIG. 11A to FIG. 11B The discussion can be applied to FIG. 15 and FIG. 3 to FIG. 8B .

[0287] FIG. 3 to FIG. 8B The RAN (e.g.) was shown. FIG. 16A RAN 105, or base stations 104, 106, or DU 174, 174A, 174B, or 174C) and UE (e.g., FIG. 3 to FIG. 8B Example method 1500 for handling uplink synchronization time alignment timers in UE 102.

[0288] Method 1500 begins at block 1501, where the RAN performs the actions described in blocks 1202, 1209, 1218, 1225, 1227, 1259, and 1247. At block 1572, while the first time alignment timer is running, the RAN detects that the second time alignment has expired. At block 1574, the RAN, in response to this detection, keeps the first time alignment timer running.

[0289] FIG. 3 to FIG. 8B The RAN (e.g.) was shown. FIG. 16B RAN 105, or base stations 104, 106, or DU 174, 174A, 174B, or 174C) and UE (e.g., FIG. 10A to FIG. 10C Example method 1600A for handling uplink synchronization time alignment timers in UE 102.

[0290] Method 1600A begins at block 1601, where the RAN performs the actions described in blocks 1202, 1209, 1218, 1225, 1227, 1259, and 1247. At block 1673, while the second time alignment timer is running, the RAN detects that the first time alignment has expired. At block 1675, the RAN, in response to this detection, keeps the second time alignment timer running.

[0291] FIG. 12A to FIG. 12BThis is a flowchart of an example method 1600B, similar to method 1600A, except that method 1600B includes block 1677 instead of block 1675. At block 1677, the RAN stops the second time alignment timer in response to the detection.

[0292] right FIG. 15 and FIG. 16A The discussion can be applied to FIG. 16B , FIG. 15 and FIG. 16A Similarly, regarding FIG. 16B , FIG. 10A to FIG. 9C and FIG. 12A to FIG. 12B The description can be applied to FIG. 17A and FIG. 3 to FIG. 8B .

[0293] FIG. 3 to FIG. 8B The UE (e.g.) was demonstrated FIG. 17B UE 102) and RAN (e.g., FIG. 17C Example method 1700A for handling uplink synchronization time alignment timers in RAN105 or base stations 104, 106.

[0294] Method 1700A begins at block 1702, where the UE communicates with the RAN via the serving cell (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, 780, 880, and 881). At block 1709, while communicating with the RAN via the serving cell, the UE starts a first time alignment timer for uplink synchronization with the serving cell. At block 1727, the UE sends a random access preamble to the RAN. At block 1759, in response to the random access preamble, the UE receives a random access response from the RAN, including the TA value. At block 1791A, the UE determines whether it is receiving the random access response on the serving cell or a candidate cell. If the UE determines at block 1791A that it is receiving the random access response on the serving cell, the procedure continues to block 1753. At box 1753, in response to receiving a random access response, the UE restarts the first time alignment timer. In some implementations, the UE uses the TA value to adjust the uplink transmission timing with the serving cell. Otherwise, if the UE determines at box 1791A that it has received a random access response on the candidate cell, the procedure continues to box 1747. At box 1747, in response to receiving a random access response, the UE starts a second time alignment timer. In some implementations, the UE uses the TA value to adjust the uplink transmission timing with the candidate cell.

[0295] In some implementations, the candidate cell is an LTM (e.g., a target) cell (e.g., the first cell described above). In some implementations, the UE maintains or avoids stopping the first time alignment timer when starting the second time alignment timer or in response to receiving a random access response on the candidate cell.

[0296] FIG. 9A to FIG. 9C This is a flowchart of an example method 1700B, which is similar to method 1700A, except that method 1700B includes box 1791B instead of box 1791A.

[0297] At box 1791B, the UE determines whether to send the random access preamble on the serving cell or the candidate cell. If the UE determines at box 1791B that it is sending the random access preamble on the serving cell, the procedure continues to box 1753. Otherwise, if the UE determines at box 1791B that it is sending the random access preamble on the candidate cell, the procedure continues to box 1747.

[0298] FIG. 11A to FIG. 11B This is a flowchart of an example method 1700C, which is similar to method 1700A, except that method 1700C includes box 1791C instead of box 1791A.

[0299] At box 1791C, the UE determines whether it has sent a random access preamble for early TA acquisition. If the UE determines at box 1791C that it has sent a random access preamble not used for early TA acquisition, the procedure continues to box 1753. Otherwise, if the UE determines at box 1791C that it has sent a random access preamble used for early TA acquisition, the procedure continues to box 1747.

[0300] right FIG. 13 , FIG. 14A , FIG. 14B , FIG. 17A to FIG. 17C and FIG. 17A to FIG. 17C The discussion can be applied to FIG. 9A to FIG. 9C Similarly, for FIG. 11A to FIG. 11B The discussion can be applied to FIG. 13 , FIG. 14A , FIG. 14B , FIG. 18A and FIG. 3 to FIG. 8B .

[0301] FIG. 18B The RAN (e.g.) was shown. FIG. 18C Example method 1800A for early TA acquisition of UE (e.g., UE 102) managed by RAN 105, or base station 104, 106 or DU 174, 174A, 174B or 174C in the ...DU 1

[0302] Method 1800A begins at block 1802, where the RAN communicates with the UE via the serving cell (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, 780, 880, and 881). At block 1809, while communicating with the UE via the serving cell, the RAN starts a first time alignment timer for uplink synchronization with the UE on the serving cell. At block 1827, the RAN receives a random access preamble from the UE. At block 1859, in response to the random access preamble, the RAN sends a random access response to the UE, including the TA value. At block 1891A, the RAN determines whether to send the random access response on the serving cell or a candidate cell. If the RAN determines at block 1891A that it is sending the random access response on the serving cell, the procedure continues to block 1853. At box 1853, in response to sending a random access response, the RAN restarts the first time alignment timer. Otherwise, if the RAN determines at box 1891A that it has sent a random access response on the candidate cell, the procedure continues to box 1847. At box 1847, in response to sending a random access response, the RAN starts the second time alignment timer.

[0303] In some implementations, the candidate cell is an LTM (e.g., a target) cell (e.g., the first cell described above). In some implementations, the RAN maintains or avoids stopping the first time alignment timer when starting the second time alignment timer or in response to sending a random access response on the candidate cell.

[0304] FIG. 10A to FIG. 10C This is a flowchart of example method 1800B, which is similar to method 1700A, except that method 1800B includes box 1891B instead of box 1891A.

[0305] At box 1891B, the RAN determines whether to receive the random access preamble on the serving cell or the candidate cell. If the RAN determines at box 1891B that it is receiving the random access preamble on the serving cell, the procedure continues to box 1853. Otherwise, if the RAN determines at box 1891B that it is receiving the random access preamble on the candidate cell, the procedure continues to box 1847.

[0306] FIG. 12A to FIG. 12B This is a flowchart of an example method 1800C, which is similar to method 1800A, except that method 1800C includes box 1891C instead of box 1891A.

[0307] At box 1891C, the RAN determines whether it has received the random access preamble for early TA acquisition. If the RAN determines at box 1891C that it has received the random access preamble and it was not used for early TA acquisition, the procedure continues to box 1753. Otherwise, if the RAN determines at box 1891C that it has received the random access preamble for early TA acquisition, the procedure continues to box 1847.

[0308] right FIG. 15 , FIG. 16A , FIG. 16B , FIG. 18A to FIG. 18C and FIG. 18A to FIG. 18C The discussion can be applied to FIG. 10A to FIG. 10C Similarly, for FIG. 12A to FIG. 12B The discussion can be applied to FIG. 15 , FIG. 16A , FIG. 16B , ​ and ​ .

[0309] In some implementations, the following description applies to the above description.

[0310] Generally, the description of one of the above figures applies to all of the above figures. Where there is no conflict, the examples, implementations, and methods described above are combined. The events or boxes described above are optional or omitted. For example, events or boxes with dashed lines in the figures are optional. In some implementations, “message” is used and “information element (IE)” is used instead of “message”, and vice versa. In some implementations, “IE” is used and “field” is used instead of “IE”, and vice versa. In some implementations, “configuration” is replaced by “configurations” or “configuration parameters”, and vice versa. In some implementations, “LTM command” is replaced by “serving cell change command”, “Layer 1 / Layer 2 handover command”, “lower layer handover command”, or “lower layer serving cell change command”. In some implementations, “some” means “one or more”. In some implementations, “at least one” means “one or more”. In some implementations, “DU configuration” is replaced by “cell group configuration”. In some implementations, "cell index" is replaced by "serving cell index," "LTM cell index," "Special cell (SpCell) index," "PCell index," or "PSCell index." In some implementations, "serving" is replaced by "source." In some implementations, "measurement report" is replaced by "measurement result." In some implementations, "early TA acquisition" is replaced by "early timed synchronization," "early timed synchronization with the target cell," "early TA value acquisition," or "early TA value acquisition of the target cell." In some implementations, "early TA acquisition configuration" is replaced by "early TA acquisition indication" or "early TA acquisition enable indication."

[0311] The user device that implements the technology of this disclosure (e.g., UE 102) can be any suitable device capable of wireless communication, such as a smartphone, tablet computer, laptop computer, mobile game console, point-of-sale (POS) terminal, health monitoring device, drone, camera, media streaming dongle or other personal media device, wearable device such as a smartwatch, wireless hotspot, femtocell, or broadband router. Additionally, in some cases, the user device can be embedded in an electronic system (such as the main unit of a vehicle or an advanced driver assistance system (ADAS)). Furthermore, 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, computer-readable storage, a user interface, one or more network interfaces, one or more sensors, etc.

[0312] Some embodiments described in this disclosure include logic or multiple components or modules. A module can be a software module (e.g., code or machine-readable instructions stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit capable of performing certain operations and can be configured or arranged in a certain way. A hardware module may include a dedicated circuit system or logic that is persistently configured (e.g., as a dedicated processor, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC), digital signal processor (DSP), etc.) to perform certain operations. A hardware module may also include programmable logic or circuit systems that are temporarily configured by software to perform certain operations (e.g., as encompassed within a general-purpose processor or other programmable processor). The decision to implement a hardware module in a dedicated and persistently configured circuit system or in a temporarily configured circuit system (e.g., configured by software) may be driven by cost and time considerations.

[0313] When implemented in software, the technology can be provided as part of an operating system, a library used by multiple applications, a specific software application, etc. The software can be executed by one or more general-purpose processors or one or more dedicated processors.

[0314] As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” or any other variation thereof are intended to cover non-exclusive inclusion. For example, a process, method, article, or apparatus that includes a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, unless expressly stated otherwise, “or” means inclusive or not exclusive. For example, condition A or B is satisfied by either: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); and both A and B are true (or exist).

Claims

1. A method implemented in a user equipment (UE), the method comprising: In response to obtaining the timing advance of the target cell from the radio access network (RAN) in the serving cell, start or restart the timing alignment timer of the target cell; Receive a command for initiating a lower-layer triggered mobility LTM cell change to the target cell; Reset the Media Access Control (MAC) entity in response to the command; and When the MAC entity is reset, the timer alignment timer remains running.

2. The method of claim 1, further comprising: While the timing alignment timer is running, the timing advance is used to access the target cell and communicate with the cell.

3. The method as described in claim 1 or 2, wherein: The timer that maintains the timing alignment is a response to determining that the LTM command includes the timing advance.

4. The method of claim 1, wherein, Obtaining the timing advance includes: Receive a command for transmitting a random access preamble in the target cell, and The timing advance is received in the random access response message.

5. The method as described in any one of the preceding claims, further comprising: Before receiving the command for initiating the LTM cell change, the LTM configuration for the target cell is received.

6. The method as described in any of the preceding claims, wherein: Starting or restarting the timing alignment timer of the target cell includes restarting the timing alignment timer; The method further includes: Before restarting the timing alignment timer of the target cell, start the timing alignment timer of the serving cell.

7. The method of any one of claims 1 to 5, further comprising: Before restarting the timing alignment timer of the target cell, start the first timing alignment timer of the serving cell; Starting or restarting the timing alignment timer of the target cell includes starting a second timing alignment timer.

8. The method of claim 7, further comprising: While the first timer alignment timer is running, the expiration of the second timer alignment timer is detected; as well as In response to the detection, the first timing alignment operation is maintained.

9. The method of claim 7, further comprising: While the second timer alignment timer is running, the expiration of the first timer alignment timer is detected; as well as In response to the detection, the second timing alignment operation is maintained.

10. The method of claim 1, further comprising: Before restarting the timing alignment timer of the target cell, start the first timing alignment timer of the serving cell; in: Starting or restarting the timing alignment timer for the target cell includes starting a second timing alignment timer in response to receiving a response to a random access preamble in a candidate cell.

11. The method of claim 1, further comprising: Before restarting the timing alignment timer of the target cell, start the first timing alignment timer of the serving cell; in: Starting or restarting the timing alignment timer of the target cell includes starting a second timing alignment timer in response to sending a random access preamble in a candidate cell.

12. The method of claim 1, further comprising: Before restarting the timing alignment timer of the target cell, start the first timing alignment timer of the serving cell; in: Starting or restarting the timing alignment timer of the target cell includes starting a second timing alignment timer in response to sending a random access preamble for early timing alignment acquisition.

13. A method implemented in a radio access network (RAN), the method comprising: Provide the target cell's timing advance to the user equipment (UE) in the serving cell; Send a command to the UE to initiate a lower-layer triggered mobility LTM cell change to the target cell; In response to the sending of the command, a timing alignment timer associated with the target cell is started; Reset the Media Access Control (MAC) entity; and When the MAC entity is reset, the timer alignment timer remains running.

14. The method of claim 14, wherein: The MAC entity is restarted in response to the determination that the command includes a timing advance value.

15. An apparatus comprising processing hardware and configured to implement the method as described in any of the preceding claims.

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