Method and apparatus for configuring parameters for lower layer triggered mobility using transmission configuration indicator

Abstract

Methods and apparatus operate within a radio access network to facilitate fast serving cell changes using a lower layer triggered mobility LTM procedure to reduce latency and overhead relative to an L3 triggered cell handover procedure. The execution of the LTM procedure is triggered by an L1 measurement report. The distributed entities of the base station exchange information (1204) for preparing the UE to switch from the current serving cell to another cell to use the LTM procedure, and communicate (1210) an LTM configuration generated (1206) in one of the distributed entities to the UE. Additionally, one or more transmission configuration indicator (TCI) state configurations may be generated (1208) and transmitted (1210) between the various distributed entities and the UE.

Description

Technical Field

[0001] This disclosure relates to wireless communications, and more specifically, to using a Transport Configuration Indicator (TCI) to configure parameters for lower-layer triggered cell changes between a User Equipment (UE) and a Radio Access Network (RAN). Background Technology

[0002] This background description is provided for the purpose of presenting the general context of this disclosure. The work of the currently attributed inventors (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 relative to this disclosure.

[0003] In telecommunications systems, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as the delivery, encryption, and integrity protection of user plane data. For example, the PDCP sublayer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP Technical Specification (TS) 36.323) and New Radio (NR) (see 3GPP TS 38.323) provides the ordering of Protocol Data Units (PDUs) in the uplink direction (from the User Equipment, also known as the UE, to the Base Station (BS)) and in the downlink direction (from the BS to the UE). Additionally, the PDCP sublayer provides Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs) to the Radio Resource Control (RRC) sublayer. The UE and BS can use SRBs to exchange RRC messages and Non-Access Stratum (NAS) messages, and can use DRBs to transmit data on the user plane.

[0004] UEs can use several types of SRBs and DRBs. When operating in dual connectivity (DC), the cell associated with the BS operating as the primary node (MN) defines a primary cell group (MCG), and the cell associated with the BS 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 SRB1 and SRB2 can be referred to as MCG SRBs. SRB3 resources allow the UE and SN to exchange SN-related RRC messages, and SRB3 can be referred to as SCG SRBs. Additionally, a DRB using only lower-layer resources of the MN can be referred to as an MCG DRB. A DRB using only lower-layer resources of the SN can be referred to as an SCG DRB. A DRB that uses the lower-layer resources of both MCG and SCG can be called a split DRB. A split DRB allows the UE to exchange RRC messages directly with the MN via the lower-layer resources of the MN and SN.

[0005] In some scenarios, a UE can concurrently utilize the resources of multiple RAN nodes (e.g., BSs or components of a distributed BS) 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 in MR-DC, one BS operates as the primary node (MN) covering the primary cell (PCell), and another BS 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 BS at a time. One BS and / or the UE determines that the UE should establish a radio connection with another BS. For example, one BS may determine to hand over the UE to a second BS and initiate a handover procedure.

[0006] When a UE moves from the coverage area of ​​one cell in the RAN to the coverage area of ​​another cell, a serving cell change is performed for the UE. To perform the serving cell change, the RAN configures the UE to send Layer 3 (L3) measurements. Based on the L3 measurements received from the UE, the RAN sends an RRC reconfiguration message to the UE. The RRC reconfiguration message triggers a synchronized reconfiguration (e.g., the RRC reconfiguration message includes...). ReconfigurationWithSyncThe RAN (Transmission Configuration Indicator) is used to change / switch serving cells (e.g., PCell or PSCell). When a UE operates with at least one secondary cell (SCell) and carrier aggregation (CA) with a PCell or PSCell, the RAN releases at least one SCell due to the change in PCell or PSCell. Serving cell changes involve a complete Layer 2 (L2) (and Layer 1 (L1)) reset, resulting in long latency, high overhead, and long downtime. Recently developed lower-layer triggered mobility (LTM) techniques do not use L3 reporting. These techniques reduce latency and overhead, thereby enabling faster serving cell handover. Configuring LTM parameters for this situation remains problematic and, if not addressed efficiently, undermines the advantages of LTM. For example, when a UE moves from one cell to another, it may need to switch to a different beam to maintain connectivity with the RAN. However, current procedures do not provide either how the RAN and UE can seamlessly switch to different beams from one cell to another during LTM (i.e., the Transport Configuration Indicator (TCI) state) or how to provide transport configuration to distributed network entities. Summary of the Invention

[0007] LTM technology reduces the latency and overhead of conventional cell handover because, for LTM, the UE does not require explicit RRC signaling and lower-layer resets. The network can initiate an LTM cell change process based on L1 measurement reports. According to various embodiments, the BS, including centralized unit (CU) and distributed unit (DU), sends information related to lower-layer measurements and reports (e.g., reference signal configuration and / or L1 measurement report configuration) along with the LTM DU configuration to the UE. Upon receiving the L1 measurement report, the BS can instruct the UE to change the serving cell used for communication. According to embodiments, the LTM DU configuration and TCI state configuration are exchanged between various entities (e.g., UE, DU, CU, etc.) to configure parameters for LTM cell handover and achieve seamless communication. Attached Figure Description

[0008] Figure 1A This is a block diagram of an example system in which the RAN and UE implement various techniques disclosed herein for transmitting LTM and TCI state configurations between the UE and the distributed BS.

[0009] Figure 1B It is possible Figure 1A A block diagram of an example base station operating in the system, including CU and DU.

[0010] Figure 2A This is a block diagram of an example protocol stack. Figure 1A The UE communicates with the BS according to the protocol stack.

[0011] Figure 2B This is a block diagram of an example protocol stack. Figure 1A The UE communicates with the CU and DU of the BS according to the protocol stack.

[0012] Figure 2C This is a block diagram illustrating the structural elements of a network element and / or a BS configured to perform methods for managing LTM configuration and TCI state configuration according to an embodiment.

[0013] Figure 3 A signaling diagram is shown for a first scenario of operation for a UE and a BS having a single DU, according to an embodiment.

[0014] Figure 4 A signaling diagram for a second scenario of operation for a UE and a BS having multiple DUs, according to another embodiment, is shown.

[0015] Figure 5A and Figure 5B A signaling diagram for a third scenario of operation for a UE and multiple BSs according to other embodiments is shown.

[0016] Figure 6A and Figure 6B A signaling diagram for a fourth scenario of operation for a UE and multiple BSs according to other embodiments is shown, wherein at least one BS has multiple DUs.

[0017] Figure 7A and Figure 7B A signaling diagram is shown for a fifth scenario in which two DUs for the UE and BS operate in dual connectivity, according to some embodiments.

[0018] Figure 8A and Figure 8B A signaling diagram is shown for a sixth scenario in which two of the multiple DUs for the UE and BS operate with dual connectivity, according to some other embodiments.

[0019] Figure 9A and Figure 9B This is a flowchart of a CU method for generating and sending TCI state configurations for LTM, according to various embodiments.

[0020] Figure 10 This is a flowchart of a CU method for sending TCI state configuration for LTM according to an embodiment.

[0021] Figure 11 This is a flowchart of a DU method for sending TCI state configuration for LTM according to an embodiment.

[0022] Figure 12A and Figure 12BThis is a flowchart of a DU method for generating and sending TCI state configurations for LTM, according to various embodiments.

[0023] Figure 13A and Figure 13B This is a flowchart of a DU method for generating a TCI state configuration for an LTM based on a received TCI state configuration, according to various embodiments.

[0024] Figure 14A and Figure 14B This is a flowchart of a DU method according to various embodiments for generating a TCI state configuration and an LTM DU configuration based on a received TCI state configuration.

[0025] Figure 15 This is a flowchart of a DU method for generating additional service DU configurations based on LTM DU configuration and TCI state configuration, according to an embodiment.

[0026] Figure 16 This is a flowchart of a DU method for generating an LTM DU configuration based on a received LTM DU configuration, according to an embodiment.

[0027] Figure 17 This is a flowchart of a CU method for transmitting LTM DU configuration based on a reference signal resource configuration, according to an embodiment.

[0028] Figure 18 This is a flowchart of a CU method for generating an LTM DU configuration based on a transmitted LTM DU configuration, according to an embodiment. Detailed Implementation

[0029] The methods and apparatus described in this section embody techniques for preparing the corresponding DU of the UE and / or BS for LTM-based cell changes when using TCI state configuration. Before discussing these techniques, an example wireless communication system 100 is introduced.

[0030] Figure 1A A wireless communication system 100 is depicted in which communication devices can implement the techniques discussed in this disclosure. The wireless communication system 100 includes a UE 102, a first BS 104, a second BS 106, and a core network (CN) 110. The UE 102 is initially connected to the first BS 104. In some scenarios, the first BS 104 can perform SN addition to configure the UE 102 to operate in dual connectivity (DC) with both the first BS 104 and the second BS 106. BS 104 and 106 act as the MN and SN of the UE 102, respectively.

[0031] In various configurations of the wireless communication system 100, the first BS 104 can be implemented as a primary eNB (MeNB) or a primary gNB (MgNB), and the second BS 106 can be implemented as a secondary gNB (SgNB). The UE 102 can communicate with the first BS 104 and the second BS 106 via the same RAT (such as EUTRA or NR) or different RATs. When the first BS 104 is a MeNB and the second BS 106 is an SgNB, the UE 102 can be in EUTRA-NR DC (EN-DC) with both the MeNB and the SgNB.

[0032] In some cases, the MeNB or SeNB is implemented as an ng-eNB instead of an eNB. When BS 104 is the primary ng-eNB (Mng-eNB) and BS 106 is the SgNB, UE 102 can be in a next-generation (NG) EUTRA-NRDC (NGEN-DC) with both the Mng-eNB and the SgNB. When BS 104 is the MgNB and BS 106 is the SgNB, UE 102 can be in an NR-NRDC (NR-DC) with both the MgNB and the SgNB. When BS 104 is the MgNB and BS 106 is the secondary ng-eNB (Sng-eNB), UE 102 can be in an NR-EUTRA DC (NE-DC) with both the MgNB and the Sng-eNB.

[0033] In an embodiment where UE 102 switches from a first BS 104 to a second BS 106, BS 104 and 106 operate as a source BS (S-BS) and a target BS (T-BS), respectively. For example, before the handover, UE 102 can work with the first BS 104 and the additional BS (T-BS). Figure 1A (Not shown in the diagram) operates in DC mode. After the handover is complete, UE 102 can continue to operate in DC mode with the second BS 106 and the additional BS, or in single-connection (SC) mode with the second BS 106. In this case, BS 104 and 106 operate as the source MN (S-MN) and the destination MN (T-MN), respectively.

[0034] CN 110 can be either the Evolved Packet Core (EPC) 111 or the 5th Generation Core (5GC) 160; both are... Figure 1AThe first BS 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. BS 104 and 106 may support X2 or Xn interfaces to directly exchange messages with each other during the embodiments 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 generally 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 deliver 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.

[0035] like Figure 1A As shown, the first BS 104 supports cell 124 (referred to as the serving cell in this disclosure), and the second BS 106 supports cell 126. Cells 124A and 126 may partially overlap, allowing the UE 102 to communicate with the first BS 104 and the second BS 106 via DC, where one of BS 104 and 106 is the MN and the other is the SN. The first BS 104 may support additional cells (such as cells 124B and 124C), and the second BS 106 may support additional cells (such as cells 124B and 124C). Figure 1A (Not shown in the diagram). Cells 124A, 124B, and 124C may partially overlap, allowing UE 102 to communicate with the first BS 104 using CA. The first BS 104 may operate cells 124A, 124B, and 124C via one or more Transmit and Receive Points (TRPs). More specifically, when UE 102 operates in DC mode with the first BS 104 and the second BS 106, one of BS 104 and 106 operates as a MeNB, Mng-eNB, or MgNB, while the other operates as an SgNB or Sng-eNB.

[0036] Generally, the wireless communication network 100 may include any suitable number of BSs supporting NR cells and / or EUTRA cells. More specifically, the EPC 111 or 5GC 160 may be connected to any suitable number of BSs 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 technologies and / or core network technologies, such as sixth-generation (6G) radio access and / or 6G core networks or 5G NR-6G DC.

[0037] Continue to refer to Figure 1A The first BS 104 is equipped with processing hardware 130, which may include one or more general-purpose processors (e.g., CPUs) and a non-transitory computer-readable storage memory for storing instructions, the one or more general-purpose processors executing the instructions. Additionally or alternatively, processing hardware 130 may include dedicated processing units. Processing hardware 130 may include a PHY controller 132 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 a physical downlink (DL) channel and a DL reference signal. PHY controller 132 is also 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 a physical uplink (UL) channel and / or a UL reference signal. Processing hardware 130 may include a MAC controller 134 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 equipment (UEs), and / or communicating UL / DL MAC PDUs with one or more UEs. Processing hardware 130 may also include an RRC controller 136 configured to implement procedures and message passing at the RRC sublayer of the protocol communication stack. For example, RRC controller 136 may be configured to support RRC message passing associated with handover procedures, and / or support necessary operations when the first BS 104 operates as an MN relative to the SN or an SN relative to the MN. The second BS 106 may include processing hardware 140 similar to processing hardware 130. Specifically, components 142, 144, and 146 may be similar to components 132, 134, and 136, respectively.

[0038] 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. PHY controller 152 is also configured to receive data and control signals on a physical DL channel and / or DL ​​reference signal via one or more cells (e.g., cells 124A, 124B, 124C, and / or 126) and / or one or more TRPs with a first BS 104 or a second BS 106. PHY controller 152 is also configured to transmit data and control signals on a physical UL channel and / or UL reference signal via one or more cells (e.g., cells 124A, 124B, 124C, and / or 126) and / or one or more TRPs with a first BS 104 or a second BS 106. In an example embodiment, processing hardware 150 includes a MAC controller 154 configured to perform MAC functions with the first BS 104 or the second BS 106. For example, MAC functions include random access procedures, managing UL timing advances for one or more user facilities, and communicating UL / DL MAC PDUs with the first BS 104 or the second BS 106. Processing hardware 150 may also include an RRC controller 156 to implement procedures and message passing at the RRC sublayer of the protocol communication stack.

[0039] In operation, UE 102, located in DC, can use radio bearers (e.g., DRB or SRB) that terminate at MN 104 or SN 106 at different times. When communicating on radio bearers in the UL (from UE 102 to BS) and / or DL ​​(from BS to UE 102) directions, UE 102 can apply one or more security keys.

[0040] Figure 1BAn example of a distributed configuration of BS 170 (which may be a first BS 104, a second BS 106, or both, or another BS) is depicted. In this embodiment, BS 170 may include a centralized unit (CU) 172 and one or more distributed units (DUs) 174. CU 172 is equipped with processing hardware, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or dedicated processing units. In one example, CU 172 is equipped with processing hardware 130. In another example, CU 172 is equipped with processing hardware 140. In an embodiment, processing hardware 140 includes an SN RRC controller 142 configured to manage or control one or more RRC configurations and / or RRC processes when the second BS 106 operates as an SN. DU 174 is also equipped with processing hardware, 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. In some embodiments, the processing hardware includes: a 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 second BS 106 operates as an MN or SN. The processing hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0041] Figure 2A An example protocol stack 200 is shown in a simplified manner. The UE 102 can use the protocol stack to communicate with an eNB / ng-eNB 201A or a gNB / en-gNB 201B (e.g., one or more of BS 104, 106).

[0042] 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 delivery services to the NR PDCP sublayer 210. The NR PDCP sublayer 210 can then provide data delivery services to the Serving Data Adaptation Protocol (SDAP) 212 or the Radio Resource Control (RRC) sublayer. Figure 2A (Not shown in the image) provides data transfer services. In some embodiments, UE 102 supports both EUTRA and NR stacks, such as... Figure 2A As shown, this supports switching between EUTRA and NR BS and / or supports DCs via EUTRA and NR interfaces. Additionally, as... Figure 2A As shown, UE 102 can support NR PDCP 210 layering on EUTRA RLC 206A, and SDAP sublayer 212 layering on NR PDCP sublayer 210.

[0043] EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 (e.g., from an IP layer that is layered directly or indirectly on PDCP layer 208 or 210) receive packets that can be referred to as Service Data Units (SDUs) and (e.g., to RLC layer 206A or 206B) output packets that can be referred to as Protocol Data Units (PDUs). For simplicity, except where the difference between SDU and PDU is relevant, this disclosure refers to both SDU and PDU as "packets".

[0044] On the control plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 can provide SRB or RRC sublayers ( Figure 2A (Not shown) to exchange, for example, RRC messages or NAS messages. On the user plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 can provide DRBs to support data exchange. The data exchanged on NR PDCP sublayer 210 can be SDAP PDUs, IP packets, or Ethernet packets.

[0045] Figure 2BAn example protocol stack 250 is shown in a simplified manner, which UE 102 can use to communicate with DU (e.g., DU 174) and CU (e.g., CU 172). The radio protocol stack 200 is functionally split, as by... Figure 2B The radio protocol stack 250 is shown in the diagram. The CU at either BS 104 or 106 can retain all control and upper-layer functionality (e.g., RRC 214, SDAP 212, and 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.

[0046] The term Network Entity (NE) is described in this disclosure as Figure 1A The first BS is 104, the second BS is 106. Figure 1B BS 170 in Figure 2A BS 201A, 201B or Figure 2B One of units 174 or 172 in the diagram. The NE communicates wirelessly with the UE 102. Although the NE can be a BS, more generally, the term "network entity" refers to a wireless device with well-defined network functionality (e.g., the functionality of a BS is to connect the UE to the core network, including managing communications to and from the UE). The NE and UE 102 may include additional functions and interfaces omitted from the diagram for brevity.

[0047] Figure 2C The NE 170, schematically shown, can provide gNB (i.e., 5G or 6G BS) functionality. The NE's functionality can be distributed across multiple entities (e.g., CU, DU, and radio unit RU). The NE includes an antenna, a radio frequency (RF) front end, and a transceiver 282 for communicating with UE 102 and other UEs and the NE. The NE's antenna and RF front end can be tuned to one or more frequency bands (e.g., subcarriers), as defined by 3GPP LTE, 5G NR, and 6G communication standards and implemented by the transceiver.

[0048] NE 170 also includes a processor 283 and a computer-readable storage medium (CRM) 284. Processor 283 may include a single-core or multi-core processor, and the CRM includes any suitable memory / storage device other than propagating signals. For example, the memory / storage device may include random access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), and / or flash memory. CRM 284 stores device data, including network scheduling data, radio resource management data, applications, and / or operating systems, which can be executed by the processor to enable wireless communication with UE 102 and with other NEs and UEs.

[0049] CRM 284 also stores L1 measurement configurations and LTM control-related executable instructions. The NE also includes inter-BS interfaces and core network interfaces. The inter-BS interface can be a standardized interface, such as the Xn and / or X2 interfaces, used for exchanging user plane and control plane data with another NE (e.g., in the case of handover). The core network interface enables the NE to exchange user plane data and control plane information with core network functions and / or entities.

[0050] In some embodiments, the L1 measurement and LTM execution of the NE and UE can be implemented not only as software but also as hardware logic and / or circuitry.

[0051] Next, we will discuss the following: Figure 1A In several scenarios, the BS operating in the system sends a configuration to the UE 102 and later activates the configuration for communication between the UE 102 and the BS. Figures 3 to 7B Similar events presented in the figure are labeled with similar reference numerals (e.g., event 316 and...). Figure 4 A and Figure 4 Event 416 of B Figure 5A Event 516 Figure 5B Event 517 Figure 6A Event 616 Figure 6B Event 617 Figure 7A Event 716 and Figure 7B Event 717 is similar; it should be noted that events yxx and zxx are similar, where y and z are associated with reference numerals and therefore their descriptions are omitted in the following figures), where differences are discussed hereinafter where appropriate. Apart from the differences shown in the figures and discussed hereinafter, any of the alternative embodiments discussed with respect to specific events (e.g., those for messaging and processing) can be applied to events labeled with similar reference numerals in other figures.

[0052] First refer to Figure 3In scenario 300, the first BS 104 includes CU 172 and DU 174, and DU 174 operates in cell 124A (i.e., the serving cell). UE 102 is initially configured to communicate with DU 174 on serving cell 124A using the serving DU 302, and is configured to communicate with CU 172 via DU 174, for example, using the serving CU. In other words, DU 174 is the serving DU that communicates with UE 102. In some embodiments, UE 102 uses the serving DU to configure communication in cell 124A and other cells (e.g., Figure 1A UE 102 communicates with DU 174 via CA on cell 124D (not shown). DU 174 operates other cells. In other embodiments, UE 102 communicates with DU 174 only on cell 124A. In some embodiments, UE 102 communicates with DU 174 on cell 124A and / or other cells via one or more TRPs. In some embodiments, cell 124A may be a PCell. In such cases, other cells include SCells and / or additional cells associated with a PCell or SCell. In other embodiments, cell 124A may be 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, the first BS 104 may be DU 174, CU 172, or DU 174 and CU 172.

[0053] In event 302, UE 102 may transmit UL PDUs and / or UL control signals to the first BS 104 via one or more TRPs in cell 124A and / or other cells. In some embodiments, UE 102 communicates UL PDUs and / or DL ​​PDUs with the first BS 104 via a radio bearer, which may include SRBs and / or DRBs. The first BS 104 may configure the radio bearer for UE 102. In some embodiments, the UL control signals include UL control information, channel state information, Hybrid Automatic Repeat Request (HARQ) acknowledgment (ACK), HARQ negative ACK, scheduling request, and / or probe reference signals. Similarly, UE 102 may receive DL PDUs and / or DL ​​control signals from the first BS 104 via one or more TRPs in cell 124A and / or other cells. In some embodiments, the DL control signals include downlink control information (DCI) and reference signals (e.g., synchronization signal blocks, channel state information reference signals (CSI-RS), and / or tracking reference signals). The first BS 104 can transmit DCI via one or more TRPs on the physical downlink control channel (PDCCH) monitored by UE 102 in cell 124A and / or other cells.

[0054] In some embodiments, the service DU configuration includes physical layer configuration parameters, MAC configuration parameters, and / or RLC configuration parameters. In some embodiments, DU 174 may send these configuration parameters to CU 172. CU 172 generates one or more messages (e.g., RRC reconfiguration messages) including the configuration parameters and sends the one or more messages to UE 102 via DU 174. In other embodiments, DU 174 sends the configuration parameters directly to UE 102. In some embodiments, the service DU configuration is defined in 3GPP TS 38.331. CellGroupConfig IE. In other embodiments, the service DU configuration includes CellGroupConfig Configuration parameters in IE. In some embodiments, the Serving CU configuration includes PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters. In some embodiments, the Serving CU configuration includes those defined in 3GPP TS 38.331. MeasConfig IE and / or RadioBearerConfig IE, or including MeasConfig IE and / or RadioBearerConfig Configuration parameters in IE. In some embodiments, the service DU configuration includes... CSI-MeasConfig IE or configuration parameters used for Channel State Information (CSI) measurement and reporting. In other embodiments, the service CU configuration includes... CSI-MeasConfig IE or configuration parameters used for CSI measurement and reporting. In some embodiments, UE 102 receives the service CU configuration or configuration parameters in the service CU configuration from CU 172 via DU 174. In other embodiments, UE 102 receives a portion of the service CU configuration and / or a portion of the service DU configuration from a BS other than the first BS 104, and receives the remainder of these configuration parameters from the first BS 104.

[0055] When communicating with the first BS 104, UE 102 may send at least one measurement report 304 to DU 174. In some embodiments, 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 for 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 embodiments, the DU-to-CU message of event 306 is an F1 Application Protocol (F1AP) message (e.g., UL RRC MessagingIn some embodiments, 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 embodiments, the serving DU configuration or serving CU configuration includes at least one measurement configuration. In some embodiments, in event 302, UE 102 receives one or more RRC messages from CU 172 via DU 174 that include at least one measurement configuration (e.g., RRCReconfiguration (Message). Based on at least one measurement configuration, UE 102 performs measurements and sends at least one measurement report (304) to DU 174. In some embodiments, at least one measurement configuration includes an L3 measurement configuration (e.g., MeasConfig IE) and / or L1 measurement configuration. L1 measurement configuration (e.g., CSI-MeasConfig The IE (Internet Interface) may include L1 measurement resource configuration and / or L1 measurement reporting configuration. L1 measurement resource configuration can configure reference signals and / or resources for reference signals for the UE 102 to measure and obtain L1 measurement results. In some embodiments, the reference signals include CSI-RS and / or SSB. For example, the L1 measurement resource configuration is... CSI- ResourceConfig IE. In another example, the L1 measurement report configuration configures how UE 102 sends L1 measurement results / reports. For example, the L1 measurement report configuration is... CSI-ReportConfig For example, UE 102 sends an L3 measurement report to CU 172 via DU 174 according to an L3 measurement configuration. UE 102 sends an L1 measurement report to DU 174 according to an L1 measurement configuration or an L1 measurement report configuration. In one embodiment, DU 174 does not send an L1 measurement report to CU 172.

[0056] In some embodiments, the L1 measurement configuration is a new RRC IE for lower-layer triggered mobility (LTM). In some embodiments, the L1 measurement resource configuration is a new RRC IE defined for LTM in 3GPP TS 38.331. In some embodiments, the L1 measurement report configuration is a new RRC IE defined for LTM in 3GPP TS 38.331. In some embodiments, each of the L1 measurement report configurations may include a trigger event configuration that configures a trigger event to trigger UE 102 to send an L1 measurement report. If UE 102 detects a trigger event, UE 102 sends an L1 measurement report to DU 174.

[0057] In some embodiments, each of the L1 measurement reports may include at least one L1 measurement result. In some embodiments, 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 embodiments, 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 other embodiments, 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 embodiment, UE 102 transmits a portion of the L1 measurement report to DU 174 on the PUCCH and the remainder of the L1 measurement report on the Physical UL Shared Channel (PUSCH). That is, 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 of the remaining portions of the L1 measurement report, UE 102 sends a PUSCH transmission including the L1 measurement report to DU 174. In some embodiments, each of the L1 measurement reports is part of Channel State Information (CSI) (i.e., a CSI component) or a CSI. In some embodiments, UE 102 may include other CSI components in each of the PUCCH and / or PUSCH transmissions described above. In one embodiment, other CSI components include, for example, a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), a CSI-RS Resource Indicator (CRI), a Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) Resource Block Indicator (SSBRI), a Layer Indicator (LI), and / or a Rank Indicator (RI). In some embodiments, UE 102 does not send the L1 measurement report as an RRC message to DU 174.

[0058] In some embodiments, each of the L3 measurement reports may include at least one L3 measurement result. In some embodiments, at least one L3 measurement result includes at least one RSRP (value) and / or at least one SINR (value). In one embodiment, UE 102 transmits each of the L3 measurement reports to CU 172 on the PUSCH via DU 174. In some embodiments, each of the L3 measurement reports may be an RRC message (e.g., Measurement Report Message). In some embodiments, each of the L3 measurement configurations includes a specific measurement identifier (e.g., measIdEach L3 measurement report includes a specific measurement identifier in a specific L3 measurement configuration. When CU 172 receives an L3 measurement report including the measurement identifier and L3 measurement results from UE 102 via DU 174, CU 172 can determine that the L3 measurement report is associated with an L3 measurement configuration identified by the measurement identifier.

[0059] In some alternative embodiments, for each of at least one measurement report (e.g., an L1 measurement report), UE102 sends 304 a MAC control element (CE) including the measurement report to DU 174. In order to send the MAC CE, in event 304, UE102 generates one or more MAC PDUs to DU 174, each MAC PDU including one or more of the MAC CEs.

[0060] In some embodiments, UE 102 performs measurements on one or more reference signals according to at least one measurement configuration. The one or more reference signals may include one or more Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) Resource Blocks (SSBs) and / or one or more CSI-RSs. UE 102 generates 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 Figure 1A One or more reference signals are transmitted on a cell (not shown in the diagram).

[0061] After receiving one or more of at least one measurement report from UE 102 (e.g., in response to receiving one or more of at least one measurement report from UE 102), the first BS 104 (i.e., CU 172 or DU 174) determines a first cell (e.g., cell 124B) other than the serving cell for LTM UE 102 handover. It should be noted that the term "prepared cell" as used in this disclosure means preparing a DU associated with the first cell, or preparing a CU associated with the first cell, or preparing both a CU and a DU associated with the first cell. In some embodiments, the first BS 104 determines to prepare the first cell for UE 102 because at least one measurement report indicates that the first cell can be used by the first BS 104 to communicate with UE 102. In some embodiments, the first BS 104 determines to prepare the first cell for UE 102 because at least one measurement report indicates that the first cell is eligible to be a candidate cell that can be used for communication with UE 102. In some embodiments, if an L3 measurement report indicates that the signal strength and / or quality of the first cell is higher than a first predetermined threshold, i.e., it is 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 the first predetermined threshold, then CU 172 determines the first cell to be prepared for UE 102 handover. In other embodiments, if an L1 measurement report indicates that the signal strength and / or quality of the first cell is higher than a first predetermined threshold (i.e., it is 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 the first predetermined threshold), then DU 174 determines the first cell to be prepared for UE 102 handover. Therefore, either CU 172 or DU 174 can prepare the first cell for UE handover from the serving cell. Alternatively, the first BS 104 determines the first cell to be prepared for UE 102 regardless of whether a measurement report is received from UE 102.

[0062] When CU 172 determines that a first cell is ready for LTM, CU 172 sends a first CU-DU message (308) to DU 174 to prepare the first cell for UE 102. In some embodiments, CU 172 includes the cell identifier (ID) of the first cell in the first CU-DU message to request DU 174 to prepare the first cell for UE 102 for LTM. In some embodiments, CU 172 includes a reference LTM DU configuration in the first CU-DU message. For example, the cell ID 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-DU message, DU 174 generates a first LTM DU configuration (referred to herein as LTM DU configuration 1) for UE 102 for the first cell configured for LTM. DU 174 then sends a first DU-CU message (310) including LTM DU configuration 1 to CU 172 in response to the first CU-DU message. In some embodiments, DU 174 may include cell ID 1 along with LTM DU configuration 1 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). When DU 174 determines that the first cell is ready, DU 174 initiates the transmission of the first DU to CU message to CU 172, rather than responding to a CU to DU message received from CU 172. In other words, DU 174 generates LTM DU configuration 1 independently, or CU 172 instructs DU 174 to generate LTM DU configuration 1.

[0063] In some embodiments, 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 scenarios and embodiments, CU 172 may include 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 UE 102 for LTM, and DU 174 includes additional LTM DU configurations (e.g., LTM DU configuration 2, ..., N), each additional LTM DU configuration configuring a specific cell in the additional cells, as described below. In such cases, DU 174 includes the additional cell IDs associated with each additional LTM DU configuration in the first DU to CU message to indicate which LTM DU configuration is associated with which cell (ID). Cells 1 and / or 2, ..., N are candidate cells.

[0064] In some embodiments, CU 172 does not include the (reference) LTM DU 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 other embodiments, 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 embodiment, 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) to replace 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.

[0065] In some embodiments, the reference LTM DU configuration includes physical layer configuration parameters, MAC configuration parameters, and / or RLC configuration parameters. In some embodiments, the reference LTM DU configuration is defined in 3GPP TS 38.331. CellGroupConfig IE. In other embodiments, the reference LTM DU configuration includes CellGroupConfig Configuration parameters in IE. In some embodiments, the reference LTM DU configuration includes CSI-MeasConfig IE or configuration parameters used for CSI measurements and / or reporting.

[0066] In some embodiments, the reference LTM DU configuration differs from the service DU configuration. In some embodiments, a portion of the reference LTM DU configuration is the same as 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 other embodiments, the reference LTM DU configuration is the same as the service DU configuration.

[0067] After receiving the first DU to CU message, CU 172 generates an RRC reconfiguration message including LTM DU configuration 1 (e.g., RRCReconfigurationThe CU 172 sends a second CU-DU message (316) to DU 174, including an RRC reconfiguration message. In some embodiments, the CU 172 includes the reference LTM DU configuration in the RRC reconfiguration message sent in step 316. In other embodiments, the CU 172 does not include the reference LTM DU configuration in the RRC reconfiguration message 316. In some embodiments, if the CU 172 sends the reference LTM DU configuration to UE 102 during event 302, the CU 172 does not include the reference LTM DU configuration in the RRC reconfiguration message 316. In other embodiments, if the CU 172 receives the reference LTM DU configuration from DU 174, the CU 172 includes the LTM DU configuration in the RRC reconfiguration message 316. Otherwise, if the CU 172 does not receive the reference LTM DU configuration from DU 174, the CU 172 does not include the reference LTM DU configuration in the RRC reconfiguration message 316.

[0068] In some embodiments, CU 172 includes LTM DU configuration 1 and / or LTM CU configuration 1 in a first container (e.g., field / IE), and includes the first container (e.g., LTM configuration (e.g., LTM-Config IE)) in the RRC reconfiguration messages of events 316 and 318. In such cases, CU 172 generates the first container. The first container is used to instruct UE 102 not to immediately apply LTM DU configuration 1 and / or LTM CU configuration 1. In some scenarios or embodiments, UE 102 receives an RRC reconfiguration message (e.g., the RRC reconfiguration message of event 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 can immediately apply the configuration. In some embodiments, the first container includes a first add or modify list (e.g., ltm-ConfigToAddModList Fields LTM-ConfigToAddModList IE ltm- CandidateConfigToAddModList field or LTM-CandidateConfigToAddModList IE). CU 172 includes LTM DU Configuration 1 and / or LTM CU Configuration 1 in the first element (hereinafter referred to as element 1) of the first add or modify list. For example, element 1 could be an add or modify IE ( ltm-ConfigToAddMod Fields LTM- ConfigToAddMod IE ltm-CandidateConfigToAddMod field or LTM- CandidateConfigToAddMod(IE). When UE 102 receives the first add or modify list, UE 102 may store the first add or modify list, for example, as a variable in its RAM. In other alternative embodiments, DU 174 generates a first container and includes the first container in the first DU to CU message. In yet another alternative embodiment, DU 174 generates element 1 and includes element 1 in the first DU to CU message.

[0069] In some embodiments, CU 172 includes LTM CU configuration 1 in RRC reconfiguration message 316, a first container, or element 1, wherein LTM CU configuration 1 is associated with LTM DU configuration 1. To associate LTM CU configuration 1 with LTM DU configuration 1, CU 172 may include LTM CU configuration 1 and LTM DU configuration 1 in element 1. In some embodiments, CU 172 includes LTM CU configurations 2, ..., N in RRC reconfiguration message 316 or a second container, wherein LTM CU configurations 2, ..., N are associated with LTM DU configurations 2, ..., N, respectively. To associate LTM CU configurations 2, ..., N with LTM DU configurations 2, ..., N, CU 172 may include LTM CU configurations 2, ..., N and LTM DU configurations 2, ..., N, respectively in elements 2, ..., N. In other embodiments, CU 172 includes LTM CU configurations 2, ..., N associated with LTM DU configurations 2, ..., N, respectively in elements 2, ..., N. Alternatively, CU 172 does not include some or all of the LTM CU configurations for LTM DU configuration 1 and / or LTM DU configuration 2, ..., N in the RRC reconfiguration message 316.

[0070] After receiving RRC reconfiguration message 316, DU 174 sends RRC reconfiguration message 318 to UE 102. In response, UE 102 sends RRC reconfiguration complete message 320 to DU 174 (e.g., RRCReconfigurationCompleteThe DU then sends a second DU-to-CU message (322) to CU 172, including an RRC reconfiguration completion message. In some embodiments, CU 172 performs security protection on the RRC reconfiguration message (e.g., integrity protection and / or encryption). For example, CU 172 generates a Message Authentication Code (MAC-I) for integrity of the RRC reconfiguration message, encrypts the RRC reconfiguration message and MAC-I to obtain an encrypted RRC reconfiguration message and an encrypted MAC-I, and in events 316 and 318, sends a PDCP PDU including the encrypted RRC reconfiguration message and the encrypted MAC-I to UE 102 via DU 174. When UE 102 receives the PDCP PDU from CU 172 via DU 174 (i.e., events 316 and 318), UE 102 decrypts the encrypted RRC reconfiguration message and the encrypted MAC-I to obtain the RRC reconfiguration message and MAC-I and verifies whether the MAC-I is valid. If UE102 verifies an invalid MAC-I, UE102 discards or ignores the RRC reconfiguration message. In some embodiments, UE102 may perform an RRC connection reconstruction procedure in response to an invalid MAC-I. Otherwise, if UE102 verifies a valid MAC-I, UE102 may process the RRC reconfiguration. UE102 avoids applying (i.e., executing) LTM DU configuration 1 until it receives an LTM command to activate LTM DU configuration 1 (e.g., events 330, 350, 398, 380, 430, or 450).

[0071] Events 308 (optional) and 310 in Figure 3 This is collectively referred to as LTM preparation process 390 (also known as the first process). Events 316, 318, 320, and 322 are... Figure 3 This is collectively referred to as the LTM configuration delivery process 394.

[0072] In some embodiments, the first CU to DU message is UE Context Modification Request The message, and the first DU to CU message is UE context modification response or UE context modification requirements Message. In UE context modification requirements In the case of a message, CU172 can respond to UE context modification requirements Message sent to DU 174 UE context modification confirmation Message. In some embodiments, the second CU to DU message is DL RRC Message Passing Message. In other embodiments, the second CU to DU message is UE Request for amendments The message, and DU 174 can send a second DU to CU message to CU 172 in response to the second CU to DU message (e.g., UE context modification response information).

[0073] In some embodiments, CU 172 may include a reference LTM CU configuration in RRC reconfiguration message 316 or a first container. In some embodiments, CU 172 may generate LTM CU configuration 1 (i.e., a non-reference LTM CU configuration) as an incremental configuration for enhancing the reference LTM CU configuration. Similarly, CU 172 may generate some or all of LTM CU configurations 2, ..., N as incremental configurations for enhancing the reference LTM CU configuration. Alternatively, in RRC reconfiguration message 316 or the first container, CU 172 includes the reference LTM CU configuration but excludes the non-reference LTM CU configuration. In some embodiments, CU 172 includes the reference LTM CU configuration and / or the reference LTM DU configuration in an additional container (e.g., a reference LTM DU configuration), and includes the additional container in RRC reconfiguration message 316.

[0074] In some embodiments, the reference LTM CU configuration differs from the service CU configuration. In some embodiments, 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 yet other embodiments, the reference LTM CU configuration is identical to the service LTM CU configuration.

[0075] In some embodiments, CU 172 includes a 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 embodiments, CU 172 includes ID 1 in a first container or element 1. In some embodiments, CU 172 assigns ID 1.

[0076] In some embodiments, CU 172 may send ID 1 to DU 174, and DU 174 associates ID 1 with LTM DU configuration 1. In some embodiments, in a first CU-DU message, CU 172 includes ID 1 and indicates that ID 1 is associated with LTM DU configuration 1. In other embodiments, after receiving the first DU-CU message, CU 172 sends a third CU-DU message to DU 174 including ID 1, instead of including ID 1 in the first CU-DU message. In some embodiments, in the third CU-DU message, CU 172 may include LTM DU configuration 1 and ID 1 and indicate the association between ID 1 and LTM DU configuration 1. Therefore, DU 174 may directly associate ID 1 with LTM DU configuration 1. In other embodiments, in the third CU-DU message, CU 172 may include cell ID 1 and ID 1 (i.e., the first LTM ID) and indicate the association between cell ID 1 and ID 1. Therefore, DU 174 can associate 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 yet another embodiment, in the third CU to DU message, CU 172 may include LTM DU configuration 1, cell ID 1 and / or ID 1 and indicate the association between ID 1, LTM DU configuration 1 and / or cell ID 1. In some embodiments, DU 174 may send a third DU to CU 172 in response to the third CU to DU message. In some embodiments, 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 Figure 3 This is collectively referred to as LTM ID assignment process 392 or the second process. In other embodiments, CU 172 may include 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 can be omitted.

[0077] If CU 172 includes ID 1 in the first CU to DU message, DU 174 may include ID 1 in LTM DU configuration 1, the first container, or element 1. Alternatively, DU 174 may not include ID 1 in LTM DU configuration 1, the first container, and / or element 1.

[0078] In some embodiments, CU 172 includes the reference LTM DU configuration in a first container. For example, CU 172 includes the reference LTM DU configuration in a field of the first container that is different from the field of the first container that includes LTM DU configuration 1. In other embodiments, CU 172 includes the reference LTM DU configuration in the RRC reconfiguration message 316 and outside the first container. For example, CU 172 generates a third container (e.g., field / IE) to include the first container and the reference LTM DU configuration, and includes the third container in the RRC reconfiguration message 316. In yet another embodiment, DU 174 includes the reference LTM DU configuration in the first container. For example, DU 174 includes the reference LTM DU configuration in a field of the first container that is different from the field of the first container that includes LTM DU configuration 1. In yet another embodiment, DU 174 generates a fourth container (e.g., field / IE) to include the first container and the reference LTM DU configuration, and includes the fourth container in the first DU to CU message 310. In such cases, CU 172 includes the fourth container in RRC reconfiguration message 316. Alternatively, CU 172 retrieves reference LTM DU configuration and LTM DU configuration 1 from the fourth container and includes reference LTM DU configuration and LTM DU configuration 1, as described above.

[0079] In some embodiments, neither CU 172 nor DU 174 is assigned an ID for identifying the reference LTM DU configuration. In some embodiments, neither CU 172 nor DU 174 is assigned an ID for identifying the reference LTM CU configuration.

[0080] In some embodiments, LTM DU configuration 1 includes a plurality of configuration parameters for UE 102 to communicate with DU 174 on a first cell. In some embodiments, the plurality of 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 some other embodiments, the plurality of configuration parameters include special cell configurations (e.g., SpCellConfig IE) and / or one or more SCell configurations (e.g., SCellConfig (IE). In some embodiments, LTM DU configuration 1 is defined in 3GPP TS 38.331. CellGroupConfig IE. In other embodiments, LTM DU configuration 1 includes CellGroupConfig Configuration parameters in Internet Explorer.

[0081] In some embodiments, LTM CU configuration 1 includes PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters. In some embodiments, LTM CU configuration 1 includes those defined in 3GPP TS 38.331. MeasConfig IE and / or RadioBearerConfig IE, or including MeasConfig IE and / or RadioBearerConfig Configuration parameters in IE. In some embodiments, LTM DU configuration 1 includes L1 measurement configuration 1 (e.g., CSI-MeasConfig The LTM CU configuration 1 includes an L1 measurement configuration and / or at least one Transmission Configuration Indicator (TCI) status configuration. In other embodiments, the LTM CU configuration 1 includes an L1 measurement configuration and / or a TCI status configuration 1. In some embodiments, the L1 measurement configuration includes at least one Reference Signal (RS) resource configuration 1 and / or at least one Reporting configuration 1. In some embodiments, the 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 embodiments, each of the RS resource configurations 1 includes an RS resource configuration ID. In some embodiments, the RS resource configuration 1 is... CSI-ResourceConfig IE (and similar). In some embodiments, Report Configuration 1 configures one or more UL resources (e.g., PUCCH resources or PUSCH resources) on Cell 1 (i.e., the first cell) for UE 102 to transmit measurement results. In some embodiments, each of Report Configuration 1 includes one or more RS resource configuration IDs that identify one or more RS resource configurations included in RS Resource Configuration 1. In some embodiments, each configuration in TCI State Configuration 1 associates one or two DL RSs with the TCI state of the corresponding Quasi-Co-located (QCL) type. The DL RS is associated with Cell 1.

[0082] In some embodiments, DU 174 includes L1 measurement configuration 1 and / or TCI status configuration 1 in service DU configuration 1 (e.g., non-LTM DU configuration). In some embodiments, DU 174 includes the service DU configuration in a first DU to CU message. In other embodiments, DU 174 sends an additional DU to CU 172 including the service DU configuration. In some embodiments, the additional DU to CU message is... UE context modification requirements In some embodiments, CU 172 includes service DU configuration 1 in RRC reconfiguration messages 316, 318. In other embodiments, CU 172 sends another RRC reconfiguration message including service DU configuration to UE 102 via DU 174.

[0083] In some embodiments, DU 174 includes the random access configuration in LTM DU configuration 1. In other embodiments, DU 174 does not include the random access configuration in LTM DU configuration 1. In some embodiments, 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 other embodiments, if DU 174 determines that UE 102 and the first cell are not yet synchronized in UL, DU 174 determines to include the random access configuration in LTM DU configuration 1. Otherwise, if DU 174 determines that UE 102 and the first cell are already synchronized 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 a random access procedure according to the random access configuration in event 332, 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 of event 332 in response to LTM DU configuration 1 excluding the random access configuration.

[0084] In some embodiments, regardless of whether cell 124A and the first cell are synchronized, DU 174 includes the random access configuration parameters in LTM DU configuration 1 and / or references the LTM DU configuration. UE 102 performs a random access procedure based on the random access configuration parameters in event 332, as described below.

[0085] In some embodiments, if cell 124A and the first cell are synchronized, DU 174 determines to include a first indication in LTM DU configuration 1, the first indication configuring 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 other embodiments, 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 of event 332 according to or in response to the first indication. Otherwise, if LTM DU configuration 1 does not include the first indication, then UE 102 responds to LTM DU configuration 1 by excluding the first indication and performs a random access procedure in event 332 according to the random access configuration, as described below.

[0086] In some embodiments, DU 174 will perform reconfiguration with synchronization (e.g., ReconfigurationWithSync IE) is included in LTM DU configuration 1 or a special cell configuration. In other embodiments, DU 174 does not include a reconfiguration configuration with synchronization (e.g., ReconfigurationWithSyncThe IE) is included in LTM DU configuration 1 or a special cell configuration. In some embodiments, if cell 124A and the first cell are not synchronized, DU 174 determines to include the reconfiguration configuration with synchronization in LTM DU configuration 1. Otherwise, if cell 124A and the first cell are synchronized, DU 174 determines not to include the reconfiguration configuration with synchronization in LTM DU configuration 1. In other embodiments, if DU 174 determines that UE 102 and the first cell are not yet synchronized in UL, DU 174 determines to include the reconfiguration configuration with synchronization in LTM DU configuration 1. Otherwise, if DU 174 determines that UE 102 and the first cell are already synchronized in UL, DU 174 determines not to include the reconfiguration configuration with synchronization in LTM DU configuration 1. In some embodiments, if LTM DU configuration 1 includes the reconfiguration configuration with synchronization, UE 102 performs a random access procedure in event 332 in response to or according to the reconfiguration configuration with synchronization, as described below. Otherwise, if LTM DU configuration 1 does not include a reconfiguration configuration with synchronization, UE 102 skips or avoids performing the random access procedure of event 332. In some embodiments, 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 one embodiment, cell ID 1 may be a PCI. In another embodiment, cell ID 1 is a CGI. In some embodiments, cell ID 1 included in LTM DU configuration 1 is a PCI, while cell ID 1 included in the first CU to DU message is a CGI. In some other embodiments, LTM DU configuration 1 includes cell index 1 indexed to cell ID 1 or the first cell. Cell index 1 is not a cell ID. The cell index occupies fewer bits than the cell ID. In some embodiments, CU 172 sets cell index 1 to a value and includes cell index 1 in the first CU to DU message of event 308.

[0087] In some embodiments, after receiving one or more of the measurement reports for event 304 (e.g., in response to receiving one or more of the measurement reports for event 304), the first BS 104 (i.e., CU 172 or DU 174) determines additional cells (i.e., cells 2, ..., N) for LTM to prepare for UE 102. In one embodiment, the first BS 104 determines to prepare additional cells for LTM to UE 102 because at least one measurement report indicates that the additional cells can be used by the first BS 104 to communicate with UE 102. The additional cells may include cell 124C and / or cells other than cells 124A, 124B, and 124C. In some embodiments, 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, then CU 172 determines to prepare said particular cell for LTM to UE 102. In other embodiments, if the 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 to prepare the particular cell for LTM for UE 102. In one embodiment, the corresponding predetermined threshold for the additional cell may be different from the first predetermined threshold. In another embodiment, the corresponding predetermined threshold for the additional cell may be the same as the first predetermined threshold. In some embodiments, the corresponding predetermined threshold for the additional cell may be the same or different. Alternatively, the first BS 104 determines to prepare the additional cell for UE 102 regardless of whether a measurement report is received from UE 102.

[0088] When CU 172 determines that an additional cell is to be prepared, CU 172 and DU 174 initiate and execute at least one additional LTM preparation procedure (LTM preparation procedure) to prepare the additional cell for LTM, wherein each of the LTM preparation procedures is similar to procedure 390. When DU 174 determines that an additional cell is to be prepared, DU 174 and CU 172 initiate and execute at least one additional LTM preparation procedure (LTM preparation procedure) to prepare the additional cell for LTM, wherein each of the LTM preparation procedures is similar to procedure 390.

[0089] In some embodiments, CU 172 and DU 174 perform LTM preparation procedures 2, ..., N to prepare cells 2, ..., N respectively, similar to procedure 390. CU 172 may include cell IDs 2, ..., N in CU-DU messages 2, ..., N in LTM preparation procedures 2, ..., N respectively, similar to the first CU-DU message. In 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 respectively, 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" is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16. In another example, the maximum value of "N" is 4, 8, 16, or 32. The examples and embodiments of LTM DU configuration 1 can be applied to LTM DU configurations 2, ..., N.

[0090] In other embodiments, CU 172 and DU 174 perform a single LTM preparation procedure (i.e., LTM preparation procedure 390) to prepare cells 1, 2, ..., N. In such cases, DU 174 includes LTM DU configurations 1, 2, ..., N for cells 1, 2, ..., N respectively in a first DU to CU message. In the first DU to CU message, DU 174 may include cell IDs 1, 2, ..., N respectively associated with LTM DU configurations 1, 2, ..., N to indicate that LTM DU configurations 1, 2, ..., N are configured for cell IDs 1, 2, ..., N respectively. When CU 172 determines to perform LTM preparation procedure 390, CU 172 includes 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.

[0091] After receiving LTM DU configurations 2, ..., N from DU 174, CU 172 may include LTM DU configurations 2, ..., N in a first container. In some embodiments, CU 172 may include LTM DU configurations 2, ..., N in elements 2, ..., N respectively, and include elements 2, ..., N in the first container. In some embodiments, CU 172 may include the LTM IDs (i.e., ID 2, ..., N) used to identify LTM DU configurations 2, ..., N in the RRC reconfiguration message. In some embodiments, CU 172 may include ID 2, ..., N in the first container. For example, CU 172 may include ID 2, ..., N and LTM DU configurations 2, ..., N in elements 2, ..., N in a first add or modify list.

[0092] In some embodiments, CU 172 assigns IDs 2, ..., N to LTM DU configurations 2, ..., N respectively. In other embodiments, CU 172 receives IDs 2, ..., N from DU 174 in the first DU to CU message of process 390. In yet another embodiment, CU 172 receives IDs 2, ..., N from DU 174 in the DU to CU messages 2, ..., N of LTM preparation processes 2, ..., N respectively.

[0093] In some embodiments, CU 172 may perform an LTM ID assignment procedure with DU 174 for each of LTM DU configurations 2, ..., N, similar to procedure 392. In other embodiments, CU 172 may include IDs 2, ..., N and LTM DU configurations 2, ..., N in a third CU-DU message and indicate the association between IDs 2, ..., N and LTM DU configurations 2, ..., N respectively. Therefore, DU 174 may associate LTM DU configurations 2, ..., N with IDs 2, ..., N respectively. In yet another embodiment, CU 172 may include cell IDs 2, ..., N and IDs 2, ..., N in a third CU-DU message and indicate the association between cell IDs 2, ..., N and IDs 2, ..., N respectively. Therefore, DU 174 can associate LTM DU configurations 2, ..., N with ID 2, ..., N based on the association between cell ID 2, ..., N and ID 2, ..., N, and the association between cell ID 2, ..., N and LTM DU configurations 2, ..., N, respectively. In other embodiments, CU 172 can include ID 2, ..., N, cell ID 2, ..., N, and / or LTM DU configurations 2, ..., N in the second CU to DU message, as described above. Therefore, the third CU to DU message can be omitted. In yet another embodiment, CU 172 can include ID 2, ..., N in the first CU to DU message and indicate that ID 2, ..., N is associated with cell ID 2, ..., N, respectively. In one embodiment, DU 174 includes ID 2, ..., N in LTM DU configurations 2, ..., N. Therefore, CU 172 does not include ID 2, ..., N in the RRC reconfiguration message, the first container, and / or element 2, ..., N.

[0094] In some alternative embodiments, DU 174 assigns IDs 2, ..., N. In some embodiments, DU 174 includes IDs 2, ..., N in the first DU to CU message of process 390. In yet another embodiment, DU 174 includes IDs 2, ..., N in DU to CU messages 2, ..., N of LTM preparation processes 2, ..., N. CU 172 may include IDs 2, ..., N in the RRC reconfiguration message. In other embodiments, DU 174 includes IDs 2, ..., N in LTM DU configurations 2, ..., N. Therefore, CU 172 does not include the ID (e.g., LTM ID) that identifies each of LTM DU configurations 2, ..., N in the RRC reconfiguration message, the first container, and / or element 1 discussed above.

[0095] In some alternative embodiments, CU 172 may generate a second container including LTM DU configuration 2, ..., N or element 2, ..., N instead of using the first container. CU 172 then sends an additional RRC reconfiguration message including the second container to UE 102 via DU 174, substantially similar to events 316 and 318. In response to this message, UE 102 sends an additional RRC reconfiguration complete message to CU 172 via DU 174, similar to events 320 and 322. In some embodiments, the second container may be a second add or modify list (e.g., ...). ltm-ConfigToAddModList Fields LTM-ConfigToAddModList IE ltm-CandidateConfigToAddModList field or LTM-CandidateConfigToAddModList IE), and each of elements 2, ..., N can be used to add or modify IE (e.g., ltm-ConfigToAddMod Fields LTM-ConfigToAddMod IE ltm-CandidateConfigToAddMod field or LTM- CandidateConfigToAddMod (IE). When UE 102 receives the second add or modify list, UE 102 can store the second add or modify list together with the first add or modify list, for example, as a variable in its RAM.

[0096] In some embodiments, DU 174 includes cell IDs 2, ..., N in LTM DU configurations 2, ..., N to identify cells 2, ..., N. In one embodiment, each of cell IDs 2, ..., N is a PCI. In some other embodiments, LTM DU configurations 2, ..., N include cell indices 2, ..., N indexed for cell IDs 2, ..., N or cells 2, ..., N respectively. When CU 172 prepares cells 2, ..., N for LTM in process 390, CU 172 may set cell indices 2, ..., N to different values ​​and include cell indices 2, ..., N in the first CU to CU to DU message of event 308. When CU 172 prepares cells 2, ..., N in an additional LTM preparation process, CU 172 may set cell indices 2, ..., N to different values ​​and include 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 embodiments, 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.

[0097] In some embodiments, each of LTM DU configurations 1, ..., N includes physical configuration parameters, MAC configuration parameters, RLC configuration parameters, and / or L1 measurement configuration. In some embodiments, each of LTM DU configurations 1, ..., N may be as defined in 3GPP TS 38.331. CellGroupConfig IE. In other embodiments, each of the LTM DU configurations 1, ..., N includes as defined in 3GPP TS 38.331. CellGroupConfig The configuration parameters included in the IE. In some other embodiments, multiple configuration parameters in each of the LTM DU configurations include specific cell-specific configurations (e.g., SpCellConfig IE) and / or one or more SCell configurations (e.g., SCellConfig (IE). In some embodiments, LTM DU configuration 1, ..., N are defined in 3GPP specification 38.331. CellGroupConfig IE. In other embodiments, the LTM DU configuration 1, ..., N includes CellGroupConfig Configuration parameters in Internet Explorer.

[0098] In some embodiments, CU 172 may include 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. Examples and embodiments of the additional LTM CU configurations are similar to LTM CU configuration 1.

[0099] In some embodiments, CU 172 determines to release LTM DU configuration M (or element M in element 1, ..., M, where 1 ≤ M ≤ N) from LTM DU configurations 1, ..., 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 one embodiment, 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 the 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. To instruct DU 174 to release the LTM DU configuration M, CU 172 may include the cell IDM 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 embodiments, the CU-DU message and the DU-CU message are a UE context modification request message and a UE context modification response message, respectively.

[0100] In other embodiments, 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. To indicate that LTM DU configuration K is released, DU 174 may include the cell ID K or ID (i.e., LTM ID) K in the release indication (e.g., a field or IE) in the DU-to-CU message, where 1 ≤ K ≤ N. After receiving the DU-to-CU message (e.g., in response to receiving the DU-to-CU message), 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. CU 172 may send a CU-to-DU message to DU 174 in response to the DU-to-CU message. In some embodiments, 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.

[0101] After receiving an RRC reconfiguration in event 318 or sending an RRC reconfiguration complete message in event 320, UE 102 sends at least one measurement report (324) to DU 174, similar to event 304. In some embodiments, DU 174 may send a DU-CU message (326) including at least one measurement report to CU 172, similar to event 306. In other embodiments, DU 174 does not send at least one measurement report to CU 172. In some embodiments, at least one measurement report in event 324 includes an L1 measurement report or an L3 measurement report, as described above for event 304. In some embodiments, UE 102 sends at least one measurement report (324) to DU 174 on PUCCH and / or PUSCH, similar to event 304. In other embodiments, UE 102 sends at least one MAC CE (324) including at least one measurement report to DU 174, similar to event 304. In some embodiments, UE 102 does not send an L1 measurement report as an RRC message to DU 174.

[0102] In some embodiments, 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. For example, in events 302 and / or 316 and / or after events 306 or 316, CU 172 may send one or more RRC messages (e.g., including at least one measurement configuration) to UE 102 via DU 174. RRCReconfiguration (Message). One or more RRC messages may or may not include the RRC reconfiguration message of event 316. According to at least one measurement configuration, UE 102 performs measurements on one or more reference signals. The one or more reference signals may include one or more SSBs and / or one or more CSI-RSs. UE 102 obtains at least one L1 measurement result and / or at least one L3 measurement result from the measurements, and includes at least one L1 measurement result and / or at least one L3 measurement result in the at least measurement report of event 324. DU 174 transmits one or more reference signals on cell 124A, cell 1, and / or cell 2, ..., N. The one or more reference signals may be CSI-RS or SSBs.

[0103] In some embodiments, at least one measurement configuration includes an L3 measurement configuration (e.g., MeasConfig(IE), as described with respect to event 304. In other embodiments, at least one measurement configuration includes or is an L1 measurement configuration, as described above. In yet another embodiment, the L1 measurement configuration may be as defined in 3GPP TS 38.331. CSI-MeasConfig IE. The L1 measurement configuration may include RS resource configuration and / or reporting configuration. UE 102 sends a 324 L1 measurement report to DU 174 on a UL resource (e.g., a PUCCH resource or a PUSCH resource) according to the reporting configuration. DU 174 receives the L1 measurement report on the UL resource according to the reporting configuration. In some embodiments, the reporting configuration is... CSI-ReportConfig An IE or similar. In other embodiments, each of the reporting configurations is a new RRC IE. In some embodiments, each of the reporting configurations configures periodic reporting and / or event-triggered reporting of L1 measurement results.

[0104] In some embodiments, the L1 measurement report is a CSI report. In other embodiments, the L1 measurement report is a MAC CE. In some embodiments, each of the measurement reports 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 embodiments, the RS resource indicator indicates the RS or RS resource in which UE 102 performs measurements or obtains quantized measurement values. In some embodiments, the RS resource indicator includes one or more SSB resource indicators (SSBRI) and / or one or more CSI-RS resource indicators (CRI). Quantized measurement values ​​may include one or more L1-RSRP values ​​and / or one or more L1-SINR values.

[0105] In other embodiments, at least one measurement configuration includes a new type of measurement configuration (e.g., an LTM measurement configuration). The new type of measurement configuration may be newly defined in a 3GPP TS. In some embodiments, the new type of measurement configuration includes a reference signal resource configuration that configures the resources in which the DU 174 transmits reference signals. For example, the reference signal resource configuration includes CSI-RS and / or SSB. In one embodiment, the reference signal resource configuration is... CSI- ResourceConfigIE. In another embodiment, the new type of measurement configuration includes a measurement report configuration, as described above. UE 102 sends 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 this case, the measurement report may be an L1 measurement report or a new type of measurement report (e.g., an LTM measurement report). In some embodiments, the new type of measurement configuration includes configuration parameters newly defined in 3GPP TS.

[0106] After receiving at least one measurement report in event 324 (e.g., in response to receiving at least one measurement report in event 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 to cell 1). DU 174 then sends the first LTM command 330 to UE 102. In some embodiments, DU 174 sends the first LTM command to UE 102 on cell 124A. In other embodiments, DU 174 sends the first LTM command to UE 102 on cell 124D. In some embodiments, DU 174 may include ID 1 in the first LTM command to indicate LTM DU configuration 1 or element 1, and UE 102 determines (e.g., identifies) LTM DU configuration 1 or element 1 based on ID 1.

[0107] In other embodiments, DU 174 may include cell index 1, which is indexed to cell ID 1, in the first LTM command. UE 102 determines (e.g., identifies) 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, before receiving the first LTM command, UE 102 decodes LTM DU configuration 1 or element 1 to obtain cell index 1. Therefore, UE 102 identifies 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.

[0108] In another embodiment, DU 174 may include cell ID 1 in the first LTM command. 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 association 1 between cell ID 1 and LTM DU configuration 1 or element 1. In other words, before receiving the first LTM command, UE 102 decodes LTM DU configuration 1 or element 1 to obtain cell ID 1. Therefore, UE 102 identifies LTM DU configuration 1 or element 1 based on cell ID 1 (received in 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, before receiving the first LTM command, UE 102 decodes the LTM DU configuration or elements 2, ..., N to obtain cell ID 2, ..., N.

[0109] In another embodiment, DU 174 may include a bitmap instead of ID 1 or cell index 1 in the first LTM command to activate LTM DU configuration 1. The number of bits in the bitmap is greater than or equal to "N". In one embodiment, bits 1, ..., N correspond to the following: cell index 1, ..., N; ID 1, ..., N; LTM DU configuration 1, ..., N; or element 1, ..., N, 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. Therefore, UE 102 can determine cell index 1, ID 1, LTM DU configuration 1, or element 1 based on bit 1 in the bitmap set to the first value. In another embodiment, bits 0, ..., N-1 correspond to the following: 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. Therefore, UE 102 can determine cell index 1, ID 1, LTM DU configuration 1, or element 1 based on bit 0 set to the first value in the bitmap. In such embodiments, DU 174 sets the remaining bits in the bitmap to a second value to indicate that the remainder of LTM DU configurations 1, ..., N are not activated. In some embodiments, the first value is one, and the second value is zero. In other embodiments, the first value is zero, and the second value is one. Generally, if DU 174 determines that UE 102 is activated by the LTM DU configuration... L Or change the service area to a community L Then DU 174 can display the corresponding bit in the bitmap (e.g., bit 174). L or position L-1 ) is set to the first value and the remaining bits are set to the second value, where 1≤L≤N In some embodiments, DU 174 sets at most one bit in the bitmap to a first value.

[0110] After determining or identifying LTM DU configuration 1 or element 1, UE 102 then applies LTM DU configuration 1 and / or LTM CU configuration after receiving the first LTM command (e.g., in response to receiving the first LTM command).

[0111] In some embodiments, at least one measurement report of event 324 (e.g., an L1 measurement report or a new type measurement report) includes at least one measurement result for the first cell (i.e., cell 1), the TRP of the first cell, or a reference signal transmitted on the first cell. The reference signal may be 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 embodiments, DU 174 determines to activate LTM DU configuration 1 because at least one measurement result is higher than a second predetermined threshold, when at least one measurement result is higher than the second predetermined threshold, or if at least one measurement result is higher than the second predetermined threshold. In some embodiments, at least one measurement result includes an L1-RSRP value, an L1-RSRQ value, and / or an L1-SINR value. In other embodiments, at least one measurement result includes an RSRP value, an RSRQ value, and / or a SINR value of a new type measurement report. In some embodiments, the second predetermined threshold is different from the first predetermined threshold. In one embodiment, 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 another embodiment, the second predetermined threshold is equal to the first predetermined threshold. In this scenario, at least one measurement indicates that the first cell consistently exceeds either a second predetermined threshold or a first predetermined threshold. This indicates that the first cell is suitable for communication with UE 102. Therefore, for UE 102, DU 174 determines to activate LTM DU configuration 1 in response to the first cell's signal strength or quality exceeding the second predetermined threshold.

[0112] In some embodiments, at least one measurement report (e.g., an L3 measurement report) of events 324 and 326 includes at least one measurement result for the first cell. 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 a first predetermined threshold. In one embodiment, the second predetermined threshold is greater than the first predetermined threshold. In this embodiment, at least one measurement report of event 326 indicates that the signal strength or quality of the first cell is suitable for communication with UE 102. In another embodiment, the second predetermined threshold is equal to the first predetermined threshold. In this embodiment, at least one measurement report of event 326 indicates that the signal strength or quality of the first cell 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, CU 172 determines to activate LTM DU configuration 1 in response to the signal strength or quality of the first cell being higher than the second predetermined threshold. 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 embodiments, CU 172 includes ID 1 in the fourth CU-DU message. In other embodiments, CU 172 includes cell index 1 in the fourth CU-DU message.

[0113] In response to the fourth CU to DU message, DU 174 sends a 330 first LTM command to UE 102 and optionally sends a fourth DU to CU message to CU 172. In some embodiments, CU 172 includes cell index 1 in the fourth CU to DU message. Therefore, DU 174 can determine the activated LTM DU configuration 1 based on cell index 1. In other embodiments, CU 172 may include cell ID 1 in the fourth CU to DU message. Therefore, DU 174 determines the activated LTM DU configuration 1 based on cell ID 1. In yet another embodiment, CU 172 may include ID 1 in the fourth CU to DU message. Therefore, DU 174 can determine the activated LTM DU configuration 1 based on ID 1. In some embodiments, the fourth CU to DU message and the fourth DU to CU message are respectively... UE context Modification Request Messages and UE context modification response Message. In other embodiments, the fourth CU to DU message and / or the fourth DU to CU message are new interface messages. ， For example, the F1 Application Protocol (F1AP) message defined in 3GPP TS 38.473.

[0114] When it is determined that LTM DU configuration 1 is activated or the first LTM command 330 is sent, or in response to determining that LTM DU configuration 1 is activated or the first LTM command 330 is sent, DU 174 may send a DU-to-CU message 329 to CU 172 indicating that LTM is being performed. In some embodiments, DU 174 includes cell ID 1 or ID 1 (i.e., LTM ID) in the DU-to-CU message 329 to indicate that DU 174 will activate LTM DU configuration 1 or trigger a fast serving cell change (i.e., LTM serving cell change). DU may send the DU-to-CU message 329 to CU 172 before or after sending the LTM command 330.

[0115] In some embodiments, the first LTM command is a MAC CE included in a MAC PDU received by UE 102 from DU 174 in event 330. The MAC CE may be a new MAC CE defined in 3GPP TS 38.321. In one embodiment, DU 174 includes a sub-header identifying the new MAC CE in the MAC PDU, and UE 102 identifies the new MAC CE in the MAC PDU based on the sub-header. The sub-header may include a logical channel ID or an extended logical channel ID defined in 3GPP TS to identify the new MAC CE. For example, the logical channel ID or extended logical channel ID is newly defined in 3GPP TS 38.321. In other embodiments, the first LTM command is a DCI received by UE 102 on the PDCCH from DU 174 in event 330. DU 174 generates a CRC for the DCI, scrambles the CRC with UE 102's first C-RNTI, and transmits the DCI and the scrambled CRC on the PDCCH in event 330. In one embodiment, the DCI format can be an existing DCI format defined in a 3GPP TS (e.g., TS 38.212). In another embodiment, the DCI format can be a new DCI format defined in a 3GPP TS.

[0116] In some embodiments, 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.

[0117] In some embodiments, after receiving the first LTM command, UE 102 may send 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 embodiments, the acknowledgment is a HARQ ACK. In other embodiments, the acknowledgment is a MAC CE. For example, a MAC CE is an existing MAC CE defined in 3GPP TS 38.321. In another example, a MAC CE is a new MAC CE defined in 3GPP TS 38.321. In yet another embodiment, the acknowledgment is a PUCCH transmission.

[0118] In some embodiments, CU 172 sends an RRC reconfiguration message 316 in response to an L3 measurement report 306 for the first cell (i.e., procedures 390 and 392 are not performed in this embodiment). To configure UE 102 to send the L3 measurement report 306, CU 172 may send a message to UE 102 before event 306 including L3 measurement configuration (e.g., ...). MeasConfig The first RRC reconfiguration message (IE) is sent to the UE 102. In some embodiments, DU 174 sends a first LTM command 330 in response to an L1 measurement report 324 for the first cell. To configure UE 102 to send an L1 or new type measurement report 324, CU 172 may send a second RRC reconfiguration message to UE 102 including the L1 or new type measurement configuration. In some embodiments, the first RRC reconfiguration message and the second RRC reconfiguration message may be the same message (i.e., the same instance). In other embodiments, the first RRC reconfiguration message and the second RRC reconfiguration message are different messages. In some embodiments, the second RRC reconfiguration message is the RRC reconfiguration message for event 316. In other embodiments, the second RRC reconfiguration message is different from the RRC reconfiguration message for event 316.

[0119] Upon receiving a first LTM command (e.g., in response to receiving the first LTM command), 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 embodiments, upon receiving the first LTM command (e.g., in response to receiving the first LTM command) or after sending acknowledgment 331, UE 102 disconnects from cell 124A. In some embodiments, upon receiving 330 to the first LTM command or sending acknowledgment 331 (e.g., in response to receiving 330 to the first LTM command or sending acknowledgment 331), UE 102 ceases communication on cell 124A. In some embodiments, 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 embodiments, after receiving the first LTM command (e.g., in response to receiving the first LTM command), 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.

[0120] In some embodiments, 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, then in event 332, UE 102 performs a random access procedure on the first cell to connect to the first cell. For example, LTM DU configuration 1 includes a reconfiguration configuration with synchronization (e.g., ...). ReconfigurationWithSync IE) is configured so that when UE 102 receives an LTM command for the first cell, UE 102 performs a random access procedure. In other embodiments, in LTM DU configuration 1, DU 174 configures UE 102 to skip the random access procedure for LTM serving cell change to the first cell. In this case, after receiving the first LTM command, in event 332, 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. In other embodiments, DU 174 excludes a reconfiguration configuration with synchronization in LTM DU configuration 1 to enable UE 102 to skip the random access procedure for LTM serving cell change to the first cell.

[0121] In other embodiments, LTM DU configuration 1 includes a reconfiguration configuration with synchronization or a random access configuration. In such cases, DU 174 configures in the LTM command whether UE 102 performs a random access procedure on the first cell. Therefore, UE 102 determines whether to perform a random access procedure on the first cell in event 332 based on the first LTM command. In some embodiments, DU 174 includes an indication (e.g., a field) indicating skipping the random access procedure in the first LTM command. In response to the 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 other embodiments, DU 174 excludes the indication in the first LTM command to configure UE 102 to perform a random access procedure. In response to the first LTM command excluding the indication, UE 102 performs a random access procedure on the first cell to access the first cell. In some other embodiments, DU 174 includes a timing advance value in the first LTM command to indicate skipping the random access procedure. In response to receiving a timing advance value or a first LTM command including the timing advance value, UE 102 uses the timing advance value to skip the random access procedure and transmits a first transmission on the first cell to access the first cell. In yet another embodiment, DU 174 excludes the timing advance value in the first LTM command to configure UE 102 to perform a random access procedure. In response to excluding the timing advance value in the first LTM command, UE 102 performs a random access procedure on the first cell to access the first cell.

[0122] In some embodiments, the random access procedure is a four-step random access procedure. In other embodiments, the random access procedure is a two-step random access procedure. In some embodiments, the random access procedure is a contention-free random access procedure. In other embodiments, 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. DU 174 responds to message 3 by sending a contention 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. DU 174 responds to message A by sending a contention resolution message (e.g., message B) to UE 102. In some embodiments, when UE 102 receives the contention 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 embodiments, LTM DU configuration 1 includes a second C-RNTI, and the UE identifier is the second C-RNTI of UE 102. In such embodiments, the contention resolution message is a PDCCH transmission addressed to the second C-RNTI. In other embodiments, LTM DU configuration 1 does not include a C-RNTI, and the UE identifier is a first C-RNTI. In such embodiments, the contention resolution message is a PDCCH transmission addressed to the first C-RNTI.

[0123] 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 determines that UE 102 has successfully completed the random access procedure (i.e., UE 102 has successfully accessed the first cell).

[0124] If DU 174 configures UE 102 to perform a random access procedure on the first cell, as described above, then DU 174 will detect that UE 102 has accessed the first cell when it receives message 3, message A, or a special preamble during the random access procedure. If DU 174 configures UE 102 to skip the random access procedure, then DU 174 will detect that UE 102 has accessed the first cell when it receives the first transmission.

[0125] In some embodiments, UE 102 transmits a first transmission (e.g., a PUSCH transmission) on a first cell using a UL grant. In some embodiments, the first LTM command includes a UL grant. In other embodiments, when UE 102 performs an LTM serving cell change to the first cell, in response to the first LTM command, UE 102 receives a first DCI including a UL grant on the PDCCH of the first cell. In some embodiments, when UE 102 switches to the first cell in response to the 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. While 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-RNT, UE 102 uses the CRC and the second C-RNTI to determine that the first DCI was sent to UE 102. If LTM DU configuration 1 does not include a second C-RNT, UE 102 uses the CRC and the first C-RNTI to determine that the first DCI was sent to UE 102.

[0126] In some embodiments, CU 172 sends at least one first TCI state configuration to UE 102 via DU 174. In some embodiments, each of the first TCI state configurations configures a TCI state for UE 102 to transmit and / or receive data and / or control signals on a first cell. Each TCI state associates one or two DL RSs with a corresponding QCL type, and the DL RSs may be associated with a specific cell in cells 1, ..., N. In some embodiments, CU 172 receives a DU-to-CU message 310 including the first TCI state configuration from DU 174, and sends RRC messages 316 and 318 including the first TCI state configuration to UE 102 via DU 174. In other embodiments, DU 174 includes the first TCI state configuration in the serving DU configuration (e.g., ...). CellGroupConfig In the DU to CU message, the LTM DU configuration 1 is included in the first interface protocol IE / field of message 312, and the service DU configuration is included in the second interface protocol IE / field of the DU to CU message. In some embodiments, DU 174 includes LTM DU configuration 1 in the first interface protocol IE / field of message 312, and includes the service DU configuration in the second interface protocol IE / field of the DU to CU message.

[0127] In some embodiments, 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 embodiments, CU 172 avoids including the service DU configuration in a container (e.g., the first container) for LTM. In other embodiments, CU 172 includes the first TCI state configuration in an element for LTM, an add or modify list for LTM, or a container similar to element 1, the first add or modify list, or the first container. In some embodiments, the RRC message is an RRC reconfiguration message 316, 318, or another RRC reconfiguration message ( Figure 3 (Not shown in the image). In some embodiments, the DU to CU message is message 312, message 314, UE context modification response Message or UE context modification requirements In some embodiments, DU 174 also includes the first TCI state configuration in LTMDU configuration 1. In other embodiments, DU 174 avoids including the first TCI state configuration in LTMDU configuration 1.

[0128] In some embodiments, the first interface protocol IE / field is a first F1AP IE / field, and the second interface protocol IE / field is a second F1AP IE / field. In some embodiments, one of the first F1AP IE / field and the second F1AP IE / field is an F1AP CellGroupConfig IE / field, and the other is not an F1AP CellGroupConfig IE / field. In some embodiments, DU 174 includes the first F1AP IE / field in message 312. DU to CU RRC information In IE, and include the second F1AP IE / field in the DU to CU message. DU to CU RRC information In IE. In other embodiments, neither the first F1AP IE / field nor the second F1AP IE is an F1AP CellGroupConfig IE / field. In other embodiments, the second F1AP IE / field is. DU to CU RRC information IE, and the first F1AP IE / field is a new IE specifically for including LTMDU configuration.

[0129] In some embodiments, upon receiving a first LTM command (e.g., in response to receiving the first LTM command) 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 embodiments, each of the first TCI state configurations includes a TCI state ID identifying the corresponding TCI state configuration. For example, the first TCI state configurations include TCI state configurations 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 configurations 1, ..., L. DU 174 includes TCI state ID 1 in the first LTM command to instruct UE 102 to apply TCI state configuration 1 to communicate on the first cell. For example, upon receiving the first LTM command (e.g., in response to receiving the first LTM command), UE 102 uses TCI state configuration 1 based on TCI state ID 1 to access the first cell and / or communicate on the first cell. For example, UE102 uses TCI state configuration 1 to monitor one or more PDCCHs and / or send a first transmission. In some embodiments, DU174 detects UE102 accessing a first cell and communicating with UE102 on the first cell based on TCI state configuration 1. For example, DU174 receives a first transmission from UE102 on the first cell based on TCI state configuration 1.

[0130] In some embodiments, in addition to TCI State ID 1, DU 174 also includes TCI State ID 2 in the first LTM command to instruct UE 102 to apply TCI State Configuration 2 to communicate on the first cell. Upon receiving 330 to the first LTM command (e.g., in response to receiving 330 to the first LTM command), UE 102 uses TCI State Configurations 1 and 2 to access the first cell and / or communicate on the first cell 332 according to 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 uses one of TCI State Configurations 1 and 2 to send a first transmission on the first cell. In some embodiments, DU 174 detects that UE 102 has accessed a first cell and communicates with UE 102 on the first cell based on TCI state configuration 1 and / or TCI state configuration 2. For example, DU 174 receives a first transmission from UE 102 on the first cell based on one of TCI state configurations 1 and 2.

[0131] In some alternative embodiments, DU 174 may not include the TCI state ID in the first LTM command. In such cases, after receiving the first LTM command (e.g., in response to receiving the first LTM command), UE 102 uses at least one first TCI state to communicate with the first DU on the first cell. In some embodiments, DU 174 is configured based on the first TCI state to detect UE 102 accessing the first cell and to communicate with UE 102 on the first cell.

[0132] In some embodiments, before sending the first LTM command, DU 174 may send one or more activation commands to the UE to activate some or all of the first TCI state configurations. In some embodiments, each of the activation commands is a MAC CE. In other embodiments, each of the activation commands is a DCI. In some embodiments, 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, upon receiving the activation command, UE 102 determines or identifies that TCI state configuration 1 and / or TCI state configuration 2 are activated. In other embodiments, DU 174 includes all TCI state IDs of the first TCI state configuration in the activation command. Therefore, upon receiving the activation command, UE 102 determines or identifies that the first TCI state configuration is activated. In some embodiments, 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 embodiments, 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 of the TCI state IDs identifies a specific TCI state configuration in the TCI state configuration.

[0133] In some embodiments, 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 embodiments, each of the TCI state configurations configures a TCI state for UE 102 to transmit and / or receive data and / or control signals on cell 124A (i.e., the serving cell). In some embodiments, UE 102 stops using the TCI configuration after receiving a first LTM command.

[0134] After successfully accessing the first cell (i.e., handover), UE 102 uses LTM DU configuration 1 and / or reference LTM DU configuration to communicate 336 with DU 174 on the first cell and via DU 174 with CU 172. In this case, DU 174 uses LTM DU configuration 1 to communicate 336 with UE 102 on the first cell. In some scenarios or embodiments, UE 102 communicates 336 with DU 174 on the first cell via PUSCH transmission, PDSCH transmission, PUCCH transmission, PDCCH transmission, and / or sounding reference signal (SRS) transmission. In some embodiments, UE 102 uses some or all of the first TCI state configurations to perform 336 communication with DU 174. Similarly, DU 174 uses some or all of the first TCI state configurations to perform 336 communication with UE 102. In some embodiments, DU 174 includes one or more additional TCI state configurations in LTM DU configuration 1. In this scenario, DU 174 may send one or more activation commands to UE 102 via the first cell in event 336 to activate the additional TCI state configuration. Upon receiving the activation command, UE 102 determines that the additional TCI state configuration has been activated. In some embodiments, each of the activation commands is a MAC CE. In other embodiments, each of the activation commands 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 in event 336, DU 174 uses the additional TCI state configuration to communicate with UE 102 on the first cell.

[0135] 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 LTM DU configuration 1 and at least a portion of 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 LTM DU configuration 1 and at least a portion of 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.

[0136] 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 at least a portion of the reference LTM CU Configuration not enhanced by LTM CU Configuration 1 336. In this case, CU 172 communicates with UE 102 via DU 174 using LTM CU Configuration 1 and at least a portion of the reference LTMCU Configuration not enhanced by LTM CU Configuration 1 336.

[0137] 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 fully configured, 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 embodiments, if UE 102 does not receive a reference LTM CU configuration from the first BS 104, UE 102 determines that LTM CU configuration 1 is fully configured. Correspondingly, if CU 172 determines to configure LTM CU configuration 1 as fully configured or to configure LTM CU configuration 1 as fully configured, CU 172 does not send a reference LTM CU configuration to UE 102. In other embodiments, CU 172 includes a first indication (e.g., a field or IE) in LTM CU configuration 1, the first container, element 1, or the RRC reconfiguration message 316 to indicate that LTM CU configuration 1 is fully configured. If LTM CU configuration 1 is an incremental configuration for enhancing the service CU configuration, UE 102 and CU 172 communicate with each other via DU 174 336 using LTMCU configuration 1 and at least a portion of the service CU configuration not enhanced by LTM CU configuration 1. In some embodiments, if UE 102 does not receive a reference LTM CU configuration from the first BS 104, UE 102 determines that LTMCU configuration 1 is an incremental configuration for enhancing the service CU configuration. Correspondingly, if CU 172 determines to configure LTM CU configuration 1 as an incremental configuration for enhancing the service CU configuration or to configure LTM CU configuration 1 as an incremental configuration for enhancing the service CU configuration, CU 172 does not send a reference LTM CU configuration to UE 102. In some embodiments, by excluding the first indication in LTM CU Configuration 1, the first container, element 1, and / or RRC reconfiguration message 316, CU 172 indicates that LTM CU Configuration 1 is an incremental configuration for enhancing the service CU configuration. Alternatively, CU 172 includes a second indication (e.g., a field or IE) in LTM CU Configuration 1, the first container, element 1, or RRC reconfiguration message 316 to indicate that LTM CU Configuration 1 is an incremental configuration for enhancing the service CU configuration. In some embodiments, by excluding the second indication in LTM CU Configuration 1, the first container, element 1, and / or RRC reconfiguration message 316, CU 172 indicates that LTM CU Configuration 1 is a full configuration.

[0138] 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 fully configured, 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 embodiments, UE 102 and CU 172 determine that reference LTM CU configuration 1 is fully configured, as specified in the 3GPP TS. In other embodiments, CU 172 includes a first indication (e.g., a field or IE) in the reference LTM CU configuration, the first container, or the RRC reconfiguration message 316 to indicate that the reference LTM CU configuration is fully configured. 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 embodiments, CU 172 indicates 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 316. Alternatively, CU 172 includes a second indication (e.g., a field or IE) in the reference LTM CU configuration, the first container, element 1, or the RRC reconfiguration message 316 to indicate that the reference LTM CU configuration is an incremental configuration for enhancing the service CU configuration. In some embodiments, CU 172 indicates that the reference LTM CU configuration is a full configuration by excluding a second indication in the reference LTM CU configuration, the first container, element 1, and / or the RRC reconfiguration message 316.

[0139] 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.

[0140] In some embodiments, UE 102 sends an RRC message (e.g., an RRC reconfiguration complete message) to CU 172 and to the first cell via DU 174 to instruct UE 102 to apply LTM DU configuration 1. When UE 102 performs random access procedure 332, UE 102 may include the RRC message in message 3 or message A. Alternatively, UE 102 sends the RRC message after completing the random access procedure. When UE 102 skips random access procedure 332, UE 102 includes the RRC message in a PUSCH transmission within at least one PUSCH transmission. In some embodiments, if UE 102 maintains communication with the first BS 104 on cell 124A (i.e., UE 102 is not disconnected from cell 124A), UE 102 may send an RRC message to the first BS 104 via cell 124A. When DU 174 receives the RRC message, DU 174 sends the RRC message to CU 172.

[0141] In other embodiments, UE 102 avoids sending an RRC message to first BS 104 in response to applying LTM DU configuration 1 or receiving a first LTM command. In such cases, UE 102 may include or send data in message 3, message A, or PUSCH transmission, as described above. UE 102 may generate a MAC PDU and / or RLC PDU that includes said data, and send or include the MAC PDU and / or RLC PDU in PUSCH transmission. For example, the data may be 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. The MM message may be a 5G MM message or a 6G MM message, and the SM message may be a 5G SM message or a 6G SM message. When DU 174 receives the data, DU 174 sends the data to CU 172.

[0142] When DU 174 determines in event 332 or 336 that UE 102 has successfully connected to the first cell, DU 174 may send a 334 DU to CU message (e.g., access success message) to CU 172 (e.g., the CP of CU 172). In some embodiments, DU 174 may include the cell ID 1 of the first cell in the DU to CU message of event 334. The cell ID may be PCI or CGI. Therefore, CU 172 determines that UE 102 is connected to the first cell after receiving the DU to CU message of event 334. When DU 174 determines in event 332 or 336 that UE 102 has successfully connected to the first cell, DU 174 may send a DL data delivery status message or frame to CU 172 (e.g., the UP of CU 172).

[0143] In some embodiments, when or after CU 172 receives DU to CU message 329, CU 172 may stop or suspend sending DL data for UE 102 to DU 174 until DU to CU message 334 is received. CU 172 may do this because DU 174 is unable to buffer DL data for UE 102 during LTM execution in events 330 and / or 332. After receiving DU to CU message 334, CU 172 continues or resumes sending DL data for UE 102 to DU 174. In other embodiments, when CU 172 receives DU to CU message 329, CU 172 may continue sending DL data for UE 102 to DU 174. CU 172 may do this because DU 174 buffers DL data for UE 102 during LTM execution in events 330 and / or 332. When or after DU 174 detects that UE 102 has accessed cell 1, DU 174 sends DL data to UE 102 via cell 1.

[0144] In some embodiments, when it is determined that UE 102 is connected to the first cell, or when a first LTM command is sent (330), or when an acknowledgment is received (331), DU 174 may stop communicating with UE 102 on cell 124A and / or release the resources of cell 124A configured for UE 102.

[0145] In some embodiments, DU 174 may generate 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, UE 102 and DU 174 communicate with each other based on LTM DU configuration 1 instead of the serving DU configuration 336. In some embodiments, DU 174 includes an indication that LTM DU configuration 1 is a complete configuration in LTM DU configuration 1. In each of LTM DU configurations 2, ..., N, DU 174 may include an indication that the corresponding DU configuration is a complete configuration. Each of the indications in LTM DU configurations 1, ..., N may be a field or IE (i.e., the same field or IE). In other embodiments, CU 172 may include a single indication that LTM DU configuration 1 and / or 2, ..., N is a complete configuration in the RRC reconfiguration message of events 316, 318. In the case of a second container, CU 172 may include a single indication specifying that LTM DU configurations 2, ..., N are fully configured in the additional RRC reconfiguration message. In yet another embodiment, CU 172 may include a single indication specifying that LTM DU configurations 1 and / or 2, ..., N are fully configured in the first container. In yet another embodiment, for each of LTM DU configurations 2, ..., N, CU 172 may include a specific indication specifying that the corresponding LTM DU configuration is fully configured in the first container. In the case of a second container, CU 172 may include a single indication specifying that LTM DU configurations 2, ..., N are fully configured in the second container. In yet another embodiment, CU 172 may include an indication specifying that LTM DU configuration 1 is fully configured in element 1. In each of elements 2, ..., N, CU 172 may include an indication specifying that the corresponding LTM DU configuration is fully configured. UE 102 may determine that LTM DU configurations 1 and / or LTM DU configurations 2, ..., N are fully configured based on the above indications. In some embodiments, each of the above indications is consistent with that defined in the current 3GPP TS. fullConfig The fields differ. In some embodiments, each of the above indications is defined in the current 3GPP TS. fullConfig Field. If LTM DU configuration 1 is fully configured, and a reference LTM DU configuration is received from the first BS 104, for example, in RRC reconfiguration message 318, then UE 102 does not apply the reference LTM DU configuration in event 336. In such a case, DU 174 may not include the reference LTM DU configuration in the first DU to CU message 310.

[0146] In other embodiments, DU 174 may generate LTM DU configuration 1 and / or LTM DU configuration 2, ..., N as incremental configurations that enhance a portion of a reference LTM DU configuration. 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 enhance said portion of the reference LTM DU configuration with LTM DU configuration 1. Therefore, UE 102 and DU 174 communicate with each other 336 according to LTM DU configuration 1 and do not enhance a portion of the reference LTM DU configuration. In some embodiments, LTM DU configuration 1 and / or 2, ..., N, the first container, the second container, or element 1, ..., N excludes an indication that specifies LTM DU configuration 1 and / or 2, ..., N as a complete configuration to indicate that LTM DU configuration 1 and / or 2, ..., N is an incremental configuration. UE 102 can determine that each of the LTMDU configurations 1 and / or 2, ..., N is an incremental configuration based on the fact that the indication is excluded in LTMDU configurations 1 and / or 2, ..., N, first container, second container, or element 1 and / or 2, ..., N.

[0147] In some embodiments, 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.

[0148] In other embodiments, 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 such cases, UE 102 communicates with DU 174 336 based on LTM DU configuration 1 and 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 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 incremental configurations for enhancing the service DU configuration. In such cases, DU 174 communicates with UE 102 336 according to at least a portion of LTM DU configuration 1 and service DU configuration.

[0149] In some embodiments, UE 102 uses a UE MAC entity (e.g., MAC 204B) to communicate with the DU MAC entity (e.g., MAC 204B) of DU 174 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). In some embodiments, UE 102 resets the UE MAC entity after receiving a first LTM command or in response to receiving a first LTM command and before performing a random access procedure 332 or communicating with DU 174 via a first cell 336. In some embodiments, DU 174 resets the DU MAC entity after sending a first LTM command, receiving an acknowledgment 331, or determining that UE 102 is connected to the first cell (e.g., in response to sending a first LTM command, receiving an acknowledgment 331, or determining that UE 102 is connected to the first cell).

[0150] In some embodiments, when UE 102 resets the UE MAC entity, UE 102 performs at least one of the following actions on the UE MAC entity (i.e., UE MAC reset or full UE MAC reset): Configured logical channels Bj Initialize to zero; Stop one or more timers; If UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), then timeAlignmentTimer It is considered due; Set the New Data Indicator (NDI) used in the UL HARQ process to a value of 0; Set the NDI used for HARQ process ID to a value of 0 to monitor PDCCH in sidelink resource allocation mode 1; Refresh the Msg3 buffer; Refresh the MSGA buffer; Cancel (if any) the triggered scheduling request process; Cancel (if any) the triggered buffer status reporting process; Cancel (if any) the triggered power margin reporting process; Cancel any consistency LBT failures triggered (if any); Cancel any triggered BFRs; Cancel (if any) the sidelink buffer status reporting procedure that was triggered; Cancel (if any) the preemptive buffer status reporting procedure that was triggered; Cancel (if any) the timed advance reporting process that was triggered; Cancel (if any) the triggered referral rate query process; Cancel (if any) the configured uplink authorization confirmation triggered; Cancel (if any) the configured sidelink authorization verification triggered; Cancel any expected protection symbol queries triggered; Cancel (if any) the triggered positioning measurement gap activation / deactivation request process; Flush the soft buffer used for the DL HARQ process; For each of the DL HARQ processes, the next received transmission for TB is regarded as the first transmission; Release (if any) temporary C-RNTI; and Reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0151] In some embodiments, 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): Stop one or more timers; If UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), then DU 174 will be used for UE 102 to initiate and / or maintain the procedure. timeAlignmentTimer It is considered due; Set the NDI used for the DL HARQ process to a value of 0; Refresh the soft buffer used for the UL HARQ process; For each of the UL HARQ processes, the next received transmission used for the TB is considered the first transmission; and Reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0152] Depending on the embodiment, UE 102 may determine to partially or completely reset the UE MAC entity. In some embodiments, 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 other embodiments, 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 some or a subset or part of the actions in a full UE MAC reset.

[0153] In some embodiments, a partial UE MAC reset includes at least one of the following actions: If UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), then UE 102's timeAlignmentTimer It is considered due; Refresh the Msg3 buffer; Refresh the MSGA buffer; Release (if any) temporary C-RNTI; and Reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0154] In some embodiments, a partial UE MAC reset further includes at least one of the following actions: Cancel (if any) the triggered scheduling request process; Cancel (if any) the triggered buffer status reporting process; Cancel (if any) the triggered power margin reporting process; Cancel any consistency LBT failures triggered (if any); Cancel any triggered BFRs; Cancel (if any) the sidelink buffer status reporting procedure that was triggered; Cancel (if any) the preemptive buffer status reporting procedure that was triggered; Cancel (if any) the timed advance reporting process that was triggered; Cancel (if any) the triggered referral rate query process; Cancel (if any) the configured uplink authorization confirmation triggered; Cancel (if any) the configured sidelink authorization verification triggered; Cancel (if any) any expected protected symbol queries triggered; and Cancel (if any) the triggered positioning measurement gap activation / deactivation request process.

[0155] In some embodiments, a partial UE MAC reset further includes at least one of the following actions: Stop the first part of one or more timers and keep the rest of one or more timers; Set the New Data Indicator (NDI) used in the UL HARQ process to a value of 0; Set the NDI used for HARQ process ID to a value of 0 to monitor PDCCH in sidelink resource allocation mode 1; Flush the soft buffer used for the DL HARQ process; and For each of the DL HARQ processes, the next received transmission used for TB is considered the first transmission.

[0156] Depending on the embodiment, DU 174 may determine to partially or completely reset the DU MAC entity. In some embodiments, 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 other embodiments, 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 some or a subset or part of the actions in a full DU MAC reset.

[0157] In some embodiments, a partial DU MAC reset includes at least one of the following actions in a partial MAC reset: If UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), then DU 174 will be used for UE 102 to initiate and / or maintain the procedure. timeAlignmentTimer Considered due; and Reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0158] In some embodiments, a partial DU MAC reset includes at least one of the following actions for a MAC entity (i.e., a DU MAC reset): Stop the first part of one or more timers and keep the rest of one or more timers; Set the NDI used for the DL HARQ process to a value of 0; Refresh the soft buffer used for the UL HARQ process; For each of the UL HARQ processes, the next received transmission used for the TB is considered the first transmission; and Reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0159] In other embodiments, 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 acknowledgment 331, or determining that UE 102 is connected to the first cell (e.g., in response to sending the first LTM command, receiving acknowledgment 331, or determining that UE 102 is connected to the first cell). In other words, UE 102 communicates with DU 174 on the first cell using the UE MAC entity (not reset). Similarly, DU 174 communicates with UE 102 on the first cell using the DU MAC entity (not reset) during or after random access procedure 332, or after determining that UE 102 is connected to the first cell.

[0160] In some embodiments, 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) with at least one DU RLC entity (e.g., RLC 206B) of DU 174. In some embodiments, UE 102 reconstructs some or all of the at least one UE RLC entity after receiving a first LTM command or in response to receiving a first LTM command and before performing the 332 random access procedure or communicating 336 with DU 174 via the first cell. In some embodiments, DU 174 reconstructs some or all of the at least one DU RLC entity after sending a first LTM command, receiving an acknowledgment 331, or determining that UE 102 is connected to the first cell (e.g., in response to sending a first LTM command, receiving an acknowledgment 331, or determining that UE 102 is connected to the first cell).

[0161] In some embodiments, LTM DU configuration 1 may or may not include one or more RLC reconstruction indications that configure UE 102 to rebuild some or all of at least one UE RLC entity (e.g., reestablishRLC(Field). If LTM DU configuration 1 includes an RLC reconstruction indication that configures UE 102 to rebuild a first UE RLC entity among at least one UE RLC entity of the RLC PDU used by UE 102 to communicate with 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 embodiments, UE 102 may rebuild the first UE RLC entity before performing the 332 random access procedure or before communicating with DU 174 via the first cell 336. In other embodiments, UE 102 may rebuild the first UE RLC entity during 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.

[0162] In some embodiments, 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: Discard RLC SDU, RLC SDU segment, and RLC PDU (if any); Stop and reset the timer (if it is running); and Reset the state variable to its initial value.

[0163] In some embodiments, the state variables and timers are defined in 3GPP TS 38.322.

[0164] Otherwise, if LTM DU configuration 1 does not include an RLC reconstruction instruction for the first UE RLC entity, UE 102 avoids reconstructing the first UE RLC entity upon receiving the first LTM command. In other words, UE 102 avoids performing the action for reconstructing the first UE RLC entity of UE 102 upon receiving the first LTM command. In some embodiments, if LTM DU configuration 1 or element 1 does not include an RLC reconstruction instruction but includes an indication specifying that configuration 1 is fully configured, UE 102 may reconstruct the first UE RLC entity of UE 102 upon receiving the first LTM command. Otherwise, if LTM DU configuration 1 or element 1 does not include an RLC reconstruction instruction and an indication specifying that configuration 1 is fully configured, UE 102 avoids reconstructing the first UE RLC entity upon receiving the first LTM command.

[0165] 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 embodiments, DU 174 reconstructs the first DU RLC entity among at least one DU RLC entity after sending a first LTM command, receiving an acknowledgment from UE 102 for the first LTM command, or determining that UE 102 is connected to the first cell. In some embodiments, the acknowledgment is a HARQ ACK. In other embodiments, the acknowledgment is a MAC CE. In still other embodiments, the acknowledgment is a PUCCH transmission. In some embodiments, when the first BS 104 reconstructs the first DU RLC entity, DU 174 performs at least one of the following actions for the first DU RLC entity: Discard RLC SDU, RLC SDU segment, and RLC PDU (if any); Stop and reset the timer (if it is running); and Reset the state variable to its initial value.

[0166] In some embodiments, the state variables and timers are defined in 3GPP TS 38.322.

[0167] In other embodiments, UE 102 avoids rebuilding some or all of at least one UE RLC 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 acknowledgment 331, or determining that UE 102 is connected to the first cell (e.g., in response to sending the first LTM command, receiving acknowledgment 331, or determining that UE 102 is connected to the first cell). In other words, UE 102 communicates with DU 174 on the first cell using some or all of at least one UE RLC entity (not rebuilt). 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 communicates with UE 102 on the first cell during or after random access procedure 332 or after determining that UE 102 is connected to the first cell using some or all of at least one DU RLC entity (not rebuilt). For example, some or all of at least one DU RLC entity includes a first DU RLC entity and / or a second DU RLC entity.

[0168] In some embodiments, in event 302, UE 102 uses at least one UE PDCP entity (e.g., PDCP 210) to communicate UL PDCP PDUs and / or DL ​​PDCPPDUs with at least one CU PDCP entity (e.g., PDCP 210) of CU 172. In some embodiments, UE 102 performs a PDCP recovery procedure for some or all of the at least one UE PDCP entity after receiving a first LTM command or in response to receiving a first LTM command. For example, UE 102 performs a PDCP recovery procedure for the first UE PDCP entity among the at least one UE PDCP entities after receiving a first LTM command or in response to receiving a first LTM command. During the PDCP recovery procedure, UE 102 may or may not rebuild the first UE PDCP entity. After performing the PDCP recovery procedure or in response to performing the PDCP recovery procedure, in event 336, UE 102 may retransmit at least a portion of the UL PDCP PDU to CU 172 via DU 174 and the first cell. Similarly, CU 172 performs a PDCP recovery procedure for some or all of at least one CU PDCP entity after sending the first LTM command or in response to sending the first LTM command. For example, CU 172 performs a PDCP recovery procedure for the first CU PDCP entity among at least one CU PDCP entity after sending the first LTM command or in response to sending the first LTM command. In some embodiments, CU 172 performs a PDCP recovery procedure for the first CU PDCP entity in response to receiving a DU to CU message 329 or 334. In other embodiments, CU 172 performs a PDCP recovery procedure for the first CU PDCP entity in response to receiving a DL data delivery status message. During the PDCP recovery procedure, CU 172 may or may not rebuild the first CU PDCP entity. After performing the PDCP recovery procedure or in response to performing the PDCP recovery procedure, in event 336, CU 172 may retransmit at least a portion of the DL PDCP PDU to UE 102 via DU 174 and the first cell.

[0169] In other embodiments, 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, CU 172 avoids rebuilding some or more of at least one CU PDCP entity after receiving a DU to CU message 329 or 340 (e.g., in response to receiving a DU to CU message 329 or 340) or after receiving a DL data delivery status message (e.g., in response to receiving a DL data delivery status message). In other words, UE 102 communicates with CU 172 via DU 174 and the first cell using some or all of at least one UE PDCP entity (not rebuilt). 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 communicates with UE 102 via DU 174 and the first cell using some or all of at least one CU PDCP entity (not rebuilt). 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.

[0170] In some embodiments, after determining that UE 102 is connected to the first cell, CU 172 may send a 338 CU to DU message to DU 174 (e.g., UE Context Modification Request The message instructs DU 174 to stop communicating with UE 102 and / or release or suspend resources of cell 124A configured for UE 102. In response, DU 174 may stop communicating with UE 102 on cell 124A and / or release or suspend resources of cell 124A configured for UE 102, and send a 340 DU to CU message to CU-172 (e.g., UE context modification response (Message). Optional events 338 and 340 are in Figure 3 This is collectively referred to as the "resource release process" 396.

[0171] After or during communication with DU 174 on the first cell, events 344, 346, 348, 350, 351, 352, 354, and / or 356 may occur, similar to events 324, 326, 328, 330, 331, 332, 334, and / or 336, respectively. 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). The at least one measurement result indicates that the second cell is suitable for communication with UE 102 and / or the first cell is not suitable for communication with UE 102. Upon receiving at least one measurement report (e.g., in response to receiving at least one measurement report), 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). DU 174 then sends a second LTM command (350) to the UE on the first cell.

[0172] When it is determined that LTM DU configuration 2 is activated or a second LTM command is sent, or in response to activating LTM DU configuration 2 or sending a second LTM command, DU 174 may send a DU-to-CU message 349 to CU 172 indicating that an LTM command is being executed. In some embodiments, DU 174 includes cell ID 2 or ID 2 (i.e., LTM ID) in the DU-to-CU message 349 to indicate that DU 174 wants to activate LTM DU configuration 2. DU may send the DU-to-CU message 349 to CU 172 before or after sending the LTM command 350.

[0173] The descriptions for events 324, 326, 328, 330, 331, 332, 334, and / or 336 can be applied to events 344, 346, 348, 350, 351, 352, 354, and / or 356 by simple modifications. For example, replace “Cell 124A,” “First LTM Command,” “First Cell,” “ID 1,” “LTM DU Configuration 1,” and / or “LTM CU Configuration 1” with “First Cell,” “Second LTM Command,” and “Second Cell,” “ID 2,” “LTM DU Configuration 2,” and / or “LTM CU Configuration 2,” respectively.

[0174] Events 344, 346, 348, 350, 351, 352, and 354 are in Figure 3 This is collectively referred to as the "LTM execution process" 398. Events 304, 306, 390, 392, 394, 324, 326, 328, 329, 330, 331, 332, 334, 336, 396, 398, or 356 are... Figure 3This is collectively referred to as the LTM DU configuration and / or activation process 380.

[0175] Next reference Figure 4 In scenario 400, the first BS 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. Therefore, the description for scenario 300 can be broadly applied to scenario 400. The differences between scenarios 300 and 400 are described below.

[0176] Initially, UE 102 uses the serving DU to communicate with S-DU 174A 402 on cell 124A and communicates with CU 172 via S-DU 174A. S-DU 174A is the serving DU, and... Figure 3Similar to DU 174. During communication 402, UE 102 sends at least one measurement report (e.g., L1 or L3 measurement report) via S-DU 174A to CU 172, numbers 404 and 406. Based on at least one measurement report, CU 172 determines to prepare cell 1, ..., N for UE 102 for LTM (operated by T-DU 174B), where N is a positive integer greater than 0 or 1. Cell 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 (request T-DU 174B) prepare cell 1, ..., N for UE 102 for LTM. N can be a positive integer greater than zero or 1. In LTM preparation procedure 490, CU 172 sends a CU-DU message including cell IDs 1, ..., N to T-DU 174B to request T-DU 174B to prepare cells 1, ..., N for UE 102 for LTM, similar to event 308. In response, T-DU 174B sends a DU-CU message including LTM DU configurations 1, ..., N to CU 172, similar to event 310. 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, respectively. In some embodiments, the CU-DU message and DU-CU message in procedure 490 are a UE context establishment request message and a UE context establishment response message, respectively. CU 172 then sends LTM DU configurations 1, ..., N in an RRC reconfiguration message in LTM configuration delivery procedure 494, similar to LTM configuration delivery procedure 394. In some embodiments, T-DU 174B may include cell indices 1, ..., N in LTM DU configurations 1, ..., N, respectively. In some embodiments, CU 172 may set cell indices 1, ..., N to different values ​​and include cell indices 1, ..., N in the CU to DU message of process 490.

[0177] After performing LTM preparation procedure 490, CU 172 may perform an additional LTM preparation procedure with T-DU 174B to prepare cells N+1, ..., N+M for UE 102 for LTM, similar to procedure 490, where M is a positive integer greater than zero. CU 172 may determine to do so based on one or more measurement reports received from UE 102 via S-DU 174A, similar to events 404 and 406. 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 UE 102 for LTM. Cell IDs N+1, ..., N+M identify cell IDs N+1, ..., N+M, respectively. In response to the CU-DU message, T-DU 174B sends a DU-CU message to CU 172 including LTM DU configurations N+1, ..., N+M. The LTM DU configurations N+1, ..., N+M are configured for cells N+1, ..., N+M, respectively. Specifically, the LTM DU configurations N+1, ..., N+M include configuration parameters for communication on cells N+1, ..., N+M. CU 172 then sends the LTM DU configurations N+1, ..., N+M in an RRC reconfiguration message during the additional LTM DU configuration delivery process, similar to LTM configuration delivery process 394 or 494.

[0178] In some embodiments, the LTM preparation process 490 is a UE context establishment process, and the additional LTM preparation process is a UE context modification process.

[0179] In some embodiments, CU 172 and S-DU 174A may perform process 380 with UE 102, such as for Figure 3 As described. In procedure 380, CU 172 and S-DU 174A perform procedures 390 and / or 392 to prepare the S-DU174A cell for UE 102 for LTM. It should be noted that in procedure 380 or for... Figure 3 The described value N can be related to... Figure 4The described value N may be the same or different. In procedure 390, CU 172 may receive a first DU-to-CU message including a reference LTM DU configuration from S-DU 174A in event 310. In other embodiments, CU 172 and S-DU 174A do not perform procedure 380 with UE 102. In such cases, CU 172 may perform a 488 reference LTM DU configuration query procedure with S-DU 174A 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 embodiments, CU 172 may include an indication of requesting or querying the reference LTM DU configuration in the CU-to-DU message. 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 embodiments, the indication is a reference LTM DU configuration query indication. In other embodiments, the indication is an LTM indication, and CU 172 may include a query indication (e.g., GNB-DU configuration query IE) in the CU-DU message. After receiving a reference LTM DU configuration (i.e., in process 390 or process 488), CU 172 includes the reference LTM DU configuration (received from S-DU 174A) in the CU-DU message in LTM preparation process 490. T-DU 174B generates LTM DU configurations 1, ..., N based on the reference LTM DU configuration received from CU 172. In such cases, T-DU 174B does not include the reference LTM DU configuration in the DU-CU message in 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 in the additional LTM preparation process. CU 172 may not include the reference LTM DU configuration in the CU-DU message in the additional LTM preparation process with T-DU 174B. In the case of an additional LTM preparation process, the T-DU 174B generates LTM DU configurations N+1, ..., N+M based on the reference LTM DU configuration received from the CU 172.

[0180] In some embodiments, 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 an 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 this case, T-DU 174B may not include the reference LTM DU configuration in the DU-to-CU message during the additional LTM preparation procedure. In some embodiments, the reference LTM DU configuration generated by T-DU 174B is different from the reference LTM DU configuration generated by S-DU 174A. In other embodiments, the reference LTM DU configuration generated by T-DU 174B is the same as the reference LTM DU configuration generated by S-DU 174A.

[0181] In some embodiments, CU 172 includes LTM DU configurations 1, ..., N of process 380 in the CU to DU message of process 490, and T-DU 174B generates LTM DU configurations 1, ..., N and / or N+1, ..., N+M taking into account or based on the configurations in the LTM DU configurations of process 380.

[0182] In some embodiments, the LTM DU configuration X of process 380 includes at least one reference signal (RS) resource configuration X, where 1 ≤ X ≤ N. Each configuration in RS resource configuration X is associated with one or more RSs or one or more RS resources of cell X of S-DU 174A. RSs include SSB and / or CSI-RS. RS resources include SSB resources and / or CSI-RS resources. In some embodiments, each of RS resource configuration X includes an RS resource configuration ID. In some embodiments, RS resource configuration X is CSI-ResourceConfig IE (and similar). In some embodiments, the LTM DU configuration X includes CSI-MeasConfig IE, and CSI-MeasConfig IE includes CSI-ResourceConfig IE. The T-DU 174B generates at least one reporting configuration 1 for reporting measurement results of RS or RS resources on cell 1 of the T-DU 174B, and includes the reporting configuration 1 in the LTM DU configuration 1. In some embodiments, the reporting configuration 1 is CSI-ReportConfigIE (and similar). In some embodiments, the T-DU 174B generates at least one RS resource configuration 1 taking into account or based on RS resource configuration X, and includes RS resource configuration 1 in LTM DU configuration 1. In some embodiments, the T-DU 174B includes RS resource configuration X in RS resource configuration 1. In other embodiments, the T-DU 174B includes each of RS resource configuration X in RS resource configuration 1, except for the RS resource configuration ID in RS resource configuration X. The T-DU 174B assigns an RS resource configuration ID as a value for each of RS resource configuration 1 (including RS resource configuration X), and includes the RS resource configuration ID in the corresponding RS resource configuration.

[0183] In some embodiments, Report Configuration 1 configures one or more UL resources (e.g., PUCCH resources or PUSCH resources) on cell 1 for UE 102 to transmit measurement results. In some embodiments, each of 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 / handover from cell 124A to cell 1, UE 102 communicates with S-DU 174B (i.e., T-DU 17B becomes the S-DU of UE 102) and transmits measurement results on UL resources to S-DU 174B via cell 1 according to Report Configuration 1. Correspondingly, S-DU 174B receives measurement results on UL resources from UE 102 via cell 1 according to Report Configuration 1. In some embodiments, each of the measurement results 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 1 and / or Report Configuration 1, and obtains quantized measurement values ​​from the measurements. In some embodiments, the RS resource indicator indicates to the UE 102 the RS or RS resource in which it performs a measurement or obtains a quantized measurement value. In some embodiments, the RS resource indicator includes one or more SSB resource indicators (SSBRI) and / or one or more CSI-RS resource indicators (CRI). The quantized measurement value may include one or more L1-RSRP values ​​and / or one or more L1-SINR values.

[0184] In some embodiments, the T-DU 174B also includes additional RS resource configurations in LTM DU configuration 1. Each configuration in the additional RS resource configurations is associated with 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 embodiments, each of the additional RS resource configurations includes an RS resource configuration ID. In some embodiments, the additional RS resource configuration is... CSI- ResourceConfig IE (and similar). In some embodiments, the T-DU 174B will CSI-ResourceConfig IE includes CSI-MeasConfig In the IE, the T-DU 174B generates at least one additional reporting configuration for reporting measurement results of RS or RS resources on cell 1 of the T-DU 174B, and includes the additional reporting configuration in LTM DU configuration 1. In some embodiments, the additional reporting configuration is... CSI-ReportConfig IE (and similar systems).

[0185] In some embodiments, the additional report configuration configures one or more UL resources (e.g., PUCCH resources or PUSCH resources) on cell 1 for UE 102 to transmit measurement results. In some embodiments, each of the additional report configurations 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 / handover from cell 124A to cell 1, UE 102 communicates with S-DU 174B 436 and transmits measurement results on the UL resources to S-DU 174B via cell 1 according to the additional report configuration. Correspondingly, S-DU 174B receives measurement results on the UL resources from UE 102 via cell 1 according to the additional report configuration. In some embodiments, each of the measurement results 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 the additional report configuration, and obtains quantized measurement values ​​from the measurements. In some embodiments, the RS resource indicator indicates to the UE 102 an additional RS or RS resource in which it performs a measurement or obtains a quantized measurement value. In some embodiments, the RS resource indicator includes one or more SSB resource indicators (SSBRI) and / or one or more CSI-RS resource indicators (CRI). The quantized measurement value may include one or more L1-RSRP values ​​and / or one or more L1-SINR values.

[0186] Similarly, the T-DU 174B can generate 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 respectively include 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.

[0187] In other embodiments, the LTM DU configuration X of process 380 includes at least one TCI state configuration X, where 1 ≤ X ≤ N. Each configuration in the TCI state configuration X associates one or two DL RSs with a TCI state associated with a corresponding QCL type. In some embodiments, the DL RS may be associated with a cell X operated by the S-DU 174A. In some embodiments, each of the TCI state configuration X includes a TCI state ID. In some embodiments, each of the TCI state configuration X is TCI-State IE. In some embodiments, the TCI state configuration X includes / is ul-TCI-ToAddModList-r17 Fields, one or more TCI-UL-State-r17 IE dl-OrJointTCI-StateToAddModList-r17 Fields, one or more TCI- State IE TCI-ActivatedConfig IE and / or tci-StatesToAddModList Fields. In some embodiments, the LTM DU configuration X includes PDSCH-Config IE, and PDSCH-ConfigThe IE includes TCI state configuration X. In some embodiments, the 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 embodiments, TCI state configuration 1 includes TCI state configuration X. In other embodiments, the T-DU 174B includes each of TCI state configurations X in TCI state configuration 1, except for the TCI state ID in TCI state configuration X. The T-DU 174B assigns a TCI state ID as a value for each of TCI state configuration 1 (including TCI state configuration X), and includes the TCI state ID in the corresponding TCI state configuration. When UE 102 and S-DU 174B communicate with each other 436, S-DU 174B may send an LTM command to UE 102 to instruct UE 102 to perform a fast serving cell change to cell X. S-DU 174B includes the TCI state ID in the LTM command to instruct UE 102 to apply the TCI state configuration identified by the TCI state ID to communicate on cell X, wherein the TCI state configuration is one of or includes one of the TCI state configurations X.

[0188] Similarly, T-DU 174B can generate TCI state configurations 2, ..., N based on RS resource configuration X, and include 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. Therefore, at least one TCI configuration can be generated by one of CU 172, S-DU 174A, or T-DU174B.

[0189] In some embodiments, when CU 172 executes process 380 after executing process 490, CU 172 includes the LTM DU configurations 1, ..., N of process 490 in the CU to DU message of process 380, and S-DU 174A generates the LTM DU configurations 1, ..., N of process 380 in a manner similar to that described above, taking into account or based on the configurations in the LTM DU configurations of process 490.

[0190] In some embodiments, CU 172 assigns to identify (received from T-DU 174B) the IDs 1, ..., N of LTM DU configurations 1, ..., N, respectively, 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 embodiments, T-DU 174B assigns to identify (generated by T-DU 174B) the IDs 1, ..., N of LTM DU configurations 1, ..., N, respectively, and includes IDs 1, ..., N in the DU to CU message of procedure 490, similar to event 310. In some embodiments, CU 172 is assigned to identify the IDs N+1, ..., N+M of LTM DU configurations N+1, ..., N+M respectively, and performs a procedure (similar to procedure 492) with T-DU 174B to provide IDs N+1, ..., N+M and / or cell IDs N+1, ..., N+M to T-DU 174B, 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 embodiments, T-DU 174B is assigned to identify the IDs N+1, ..., N+M of LTM DU configurations N+1, ..., N+M respectively, and includes IDs 1, ..., N in the DU-to-CU message of the additional LTM preparation procedure, similar to event 310.

[0191] In some embodiments, CU 172 sends a CU-DU message 412 including IDs 1, ..., N to S-DU 174A, and in response, receives a DU-CU message 414 from S-DU 174A. The CU-DU message 412 and the DU-CU message 414 are... Figure 4This is collectively referred to as LTM ID transfer procedure 493 or LTM cell index transfer procedure 493. In some embodiments, message 412 and message 414 may be a UE context modification request message and a UE context modification response message, respectively. In some embodiments, CU 172 includes LTM DU configuration 1, ..., N and / or cell ID 1, ..., N in CU to DU message 412. In one embodiment, CU 172 includes ID 1, ..., N in CU to DU message 412. In another embodiment, CU 172 includes cell index 1, ..., N in CU to DU message 412. In some alternative embodiments, CU 172 may perform multiple LTM ID transfer 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 may include the following specific portions in a CU-DU message similar to message 412: ID 1, ..., N; Cell ID 1, ..., N; and / or LTM DU configuration 1, ..., N. Therefore, S-DU 174A associates ID 1, ..., N with LTM DU configuration 1, ..., N and / or Cell ID 1, ..., N, respectively. In other alternative embodiments, CU 172 may perform multiple LTM cell index transfer 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 may include the following specific portions in a CU-DU message similar to message 412: Cell index 1, ..., N; Cell ID 1, ..., N; and / or LTM DU configuration 1, ..., N. Therefore, S-DU 174A associates cell indices 1, ..., N with LTM DU configurations 1, ..., N and / or cell IDs 1, ..., N, respectively.

[0192] In some embodiments, 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 414. In some embodiments, the first service DU configuration includes a configuration that updates (e.g., enhances, modifies, or replaces) service DU configuration 402. In other embodiments, the first service DU configuration includes a configuration not included in service DU configuration 402. 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 the RRC reconfiguration message in procedure 494 or similar. Depending on the embodiment, UE 102 uses a configuration included in service DU configuration 402 that has not been updated by the first service DU configuration to communicate with S-DU 174A. The following are example embodiments of generating a first service DU configuration based on LTM DU configurations 1, ..., N.

[0193] In some embodiments, the LTM DU configuration Y of process 490 includes at least one RS resource configuration Y, where 1 ≤ Y ≤ N. Each configuration in RS resource configuration Y is associated with one or more RSs or one or more RS resources of 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 embodiments, each of RS resource configuration Y includes an RS resource configuration ID. In some embodiments, RS resource configuration Y is CSI- ResourceConfig IE (and similar). In some embodiments, the LTM DU configuration includes CSI-MeasConfig IE, and CSI-MeasConfig IE includes CSI-ResourceConfig IE. S-DU 174A generates at least one service reporting configuration for reporting measurement results of RS or RS resources on cell 124A, and includes the service reporting configuration in the first service DU configuration. In some embodiments, the service reporting configuration is CSI-ReportConfigIE (and similar). In some embodiments, S-DU 174A generates at least one service RS resource configuration taking into account or based on RS resource configuration Y, and includes the service RS resource configuration in a first service DU configuration. In some embodiments, S-DU 174A includes RS resource configuration Y in the service RS resource configuration. In other embodiments, S-DU 174A includes each of RS resource configurations Y in the service RS resource configuration, except for the RS resource configuration ID in RS resource configuration Y. S-DU 174A assigns an RS resource configuration ID as a value for each of the service RS resource configurations (including RS resource configuration Y), and includes the RS resource configuration ID in the corresponding service RS resource configuration.

[0194] In some embodiments, the service report configuration configures one or more UL resources (e.g., PUCCH resources or PUSCH resources) on cell 124A for UE 102 to transmit measurement results. In some embodiments, each of the service report configurations 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 transmits measurement results (e.g., event 424) on the UL resources to S-DU 174A via cell 124A according to the service report configuration. Correspondingly, S-DU 174A receives measurement results on the UL resources from UE 102 via cell 124A according to the service report configuration. In some embodiments, each of the measurement results 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 the service RS resource configuration and / or service report configuration, and obtains quantized measurement values ​​from the measurements. In some embodiments, the RS resource indicator indicates the RS or RS resource in which UE 102 performs measurements or obtains quantized measurement values. In some embodiments, the RS resource indicator includes one or more SSB resource indicators (SSBRI) and / or one or more CSI-RS resource indicators (CRI). Quantified measurements may include one or more L1-RSRP values ​​and / or one or more L1-SINR values.

[0195] In other embodiments, the LTM DU configuration Y of process 490 includes at least one TCI state configuration Y, where 1 ≤ Y ≤ N. The at least one TCI state configuration may be generated by one of CU 172, S-DU 174A, or T-DU 174B. Each configuration in the TCI state configuration Y associates one or two DL RSs with a TCI state associated with a corresponding QCL type. In some embodiments, the DL RS may be associated with a cell Y operated by T-DU 174B. In some embodiments, each of the TCI state configurations Y includes a TCI state ID. In some embodiments, each of the TCI state configurations Y is... TCI-State IE. In some embodiments, the TCI state configuration Y includes / is ul-TCI-ToAddModList-r17 Fields, one or more TCI-UL- State-r17 IE dl-OrJointTCI-StateToAddModList-r17 Fields, one or more TCI-State IE TCI-ActivatedConfig IE and / or tci-StatesToAddModList Fields. In some embodiments, the LTM DU configuration includes PDSCH-Config IE, and PDSCH-Config The IE includes TCI state configuration Y. In some embodiments, the S-DU 174A generates at least one serving TCI state configuration considering or based on TCI state configuration Y, and includes the serving TCI state configuration in a first serving DU configuration. In some embodiments, serving TCI state configuration 1 includes TCI state configuration Y. In other embodiments, the S-DU 174A includes each of the TCI state configurations Y in the serving TCI state configuration, except for the TCI state ID in the TCI state configuration Y. The S-DU 174A assigns a TCI state ID as a value for each of the serving TCI state configurations (including TCI state configuration Y), and includes the TCI state ID in the corresponding serving TCI state configuration. When the S-DU 174A communicates with the UE 102 436, the S-DU 174A may send an LTM command to the UE 102 to request the UE 102 to perform a fast serving cell change to cell Y. S-DU 174A includes the TCI State ID in the LTM command to request UE 102 to apply the TCI State Configuration identified by the TCI State ID to communicate on cell Y. The TCI State Configuration is one of or includes one of the TCI State Configurations Y.

[0196] In some embodiments, CU 172 sends a CU-DU message including IDs N+1, ..., N+M to S-DU 174A, and in response, receives a DU-CU message from S-DU 174A, similar to CU-DU message 412 and DU-CU message 414, respectively. In some embodiments, CU 172 includes LTM DU configurations N+1, ..., N+M and / or cell IDs N+1, ..., N+M in the CU-DU message. In some alternative embodiments, CU 172 may perform multiple LTM ID transfer 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 of the processes, CU 172 includes the following specific portions in a CU-DU message similar to message 412: IDs N+1, ..., N+M; cell IDs N+1, ..., N+M; and / or LTM DU configurations 1, ..., N. 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 embodiments, 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-CU message. In some embodiments, the second service DU configuration includes configurations that update (e.g., enhance, modify, or replace) the first service DU configuration and / or update configurations included in service DU configuration 402 but not updated by the first service DU configuration. In other embodiments, 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 the RRC reconfiguration message in procedure 494 or similar. Depending on the embodiment, UE 102 communicates with S-DU 174A using a configuration included in serving DU configuration 402 and / or the first serving DU configuration and not updated by the second serving DU configuration. In some embodiments, S-DU 174A generates one or more new L1 measurement configurations based on 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 embodiments, 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.

[0197] In some embodiments, when CU 172 and S-DU 174A execute procedure 380 with UE 102, the values ​​of ID 1, ..., N in procedure 380 are different from the values ​​of ID 1, ..., N and ID N+1, ..., N+M described for scenario 400. In some embodiments, when CU 172 and S-DU 174A execute procedure 380 with UE 102, the values ​​of cell ID 1, ..., N in procedure 380 are different from the values ​​of cell ID 1, ..., N and cell ID N+1, ..., N+M described for scenario 400. In some embodiments, when CU 172 and S-DU 174A execute procedure 380 with UE 102, the values ​​of cell index 1, ..., N in procedure 380 are different from the values ​​of cell index 1, ..., N and cell index N+1, ..., N+M described for scenario 400.

[0198] At a later time, UE 102 may send at least one measurement report (424) to S-DU 174A, similar to event 324. 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 a second measurement result for cell 124A. In some embodiments, the first measurement result may be or includes RSRP, RSRQ, and / or SINR obtained by UE 102 from measuring a reference signal transmitted on cell 1. Similarly, the second measurement result may be or includes RSRP, RSRQ, and / or SINR obtained by UE 102 from measuring a reference signal transmitted on cell 124A. In some embodiments, the event ID, RSRP, RSRQ, and / or SINR are L1-Event ID, L1-RSRP, L1-RSRQ, and / or L1-SINR, respectively. Based on the first measurement result and / or the second measurement result, S-DU 174A may send a first LTM command (i.e., LTM command 1) including ID 1 to UE 102, requesting UE 102 to perform a serving cell change / handover to cell 1 of T-DU 174B. In some embodiments, the first LTM command includes ID 1. In other embodiments, the first LTM command includes cell index 1. The first LTM command may also include at least one TCI state configuration. When UE 102 receives the first LTM command, UE 102 performs a serving cell change from serving cell to serving cell 1 according to LTM DU configuration 1. After receiving the first LTM command (e.g., in response to receiving the first LTM command), UE 102 may or may not perform the random access procedure with T-DU 174B, similar to event 332. Upon receiving the first LTM command or completing random access procedure 432 (e.g., in response to receiving the first LTM command or completing random access procedure 432), UE 102 can communicate with T-DU 174B on the first cell using LTMDU configuration 1 and / or reference LTMDU configuration 436, and communicate with CU 172 via T-DU 174B, similar to event 336. If a serving cell change occurs in procedure 380, the serving cell can be cell 1 of S-DU 174A (e.g., cell 124C) or cell 2. 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 LTMDU configuration 1 and / or cell ID 1 (i.e., cell 1) based on ID 1, as per [reference to previous events]. Figure 3As described. 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... Figure 3 As described. Upon receiving the first LTM command or successfully accessing cell 1 (e.g., in response to receiving the first LTM command or successfully accessing cell 1), UE 102 applies LTM DU configuration 1 (and at least one TCI state configuration) to communicate with T-DU 174B.

[0199] When it is determined that LTM DU configuration 1 is activated or a first LTM command 430 is sent, or in response to determining that LTM DU configuration 1 is activated or a first LTM command 430 is sent, the S-DU 174A may send a DU-to-CU message 429 to the CU 172 indicating that LTM is (being) executed. In some embodiments, the S-DU 174A includes cell ID 1 or ID 1 (i.e., LTM ID) in the DU-to-CU message 429 to indicate that the S-DU 174A will activate LTM DU configuration 1 or trigger an LTM serving cell change. The S-DU 174A may send the DU-to-CU message 429 to the CU 172 before or after sending the LTM command 430. In some embodiments, when or after the CU 172 receives the DU-to-CU message 429, the CU 172 may stop or suspend sending DL data for UE 102 to the S-DU 174A until the DU-to-CU message 434 is received. After receiving DU to CU message 434, CU 172 starts, continues, or resumes sending DL data for UE 102 to T-DU174B. When or after T-DU 174B detects UE 102 accessing cell 1, T-DU 174B sends DL data to UE 102 via cell 1.

[0200] The resource release procedure 496 can be similar to procedure 396. Alternatively, in the resource release procedure 496, CU 172 can send a CU-DU message to S-DU 174A (e.g., UE context release command The S-DU 174A releases the UE context of UE 102 and sends a 440 DU to CU message to CU-172 (e.g., ). UE Context release complete information).

[0201] Events 380, 404, 406, 490, 492, 494, 494, 424, 426, 428, 429, 430, 431, 432, 434, 436, 496, 498, or 456 are in Figure 4This is collectively referred to as the "LTM configuration and / or activation process" 480.

[0202] Next reference Figure 5A In scenario 500A, the second BS 106 performs the MN operation, and the first BS 104 performs the SN operation. SN 104 includes CU 172 and DU 174. Scenario 500A is similar to scenario 300, except that scenario 500A is a DC scenario, while scenario 300 is a single-connection (SC) scenario. MN 106 can include CU and DU, and... Figure 3 Similar to the first BS 104.

[0203] Initially, UE 102 communicates with MN 106 and SN 104 via 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 alternative embodiments, UE 102 does not communicate with CU 172 via DU 174 in event 302. In some embodiments, UE 102 may communicate with MN 106 and / or SN 104 via DC 502 UL PDU and / or DL ​​PDU via radio bearers, which may include SRB and / or DRB. MN 106 and / or SN 104 may configure radio bearers for UE 102. UE 102 communicates with SN 104 via DC 502 UL PDU and / or DL ​​PDU on the SCG (i.e., SCG radio resource) configured for communication with UE 102 on SN 104. UE 102 communicates with MN 106 via DC UL PDU and / or DL ​​PDU on the MCG (i.e., MCG radio resource) according to the MN configuration (i.e., MCG configuration). In some embodiments, the serving DU configuration is the SN configuration (i.e., SCG configuration). In the MN configuration, MN 106 configures the MCG, which 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 the SCG, which includes at least one serving cell (e.g., cell 124A and / or other cells) operated by SN 104. In some embodiments, the MN configuration includes multiple configuration parameters, and UE 102 receives the configuration parameters from MN 106 in one or more RRC messages. Figure 3As described, the service DU configuration includes multiple configuration parameters. In some embodiments, UE 102 receives these configuration parameters from SN 104 in one or more RRC messages, for example, via MN 106 and / or on an SRB (e.g., SRB3) configured to exchange RRC messages between UE 102 and SN 104 in MN 106 or SN 104.

[0204] When UE 102 communicates with MN 106 and SN 104 via DC, MN 106 may perform a 580 LTM DU configuration and / or activation procedure with UE 102, similar to procedures 380 and / or 480. In some embodiments, when communicating with MN 106 and SN 104 via DC, UE 102 may send at least one measurement report to CU 172 via DU 174 and cell 124A in events 504 and 506, similar to events 304 and 306. In other embodiments, when communicating with MN 106 and SN 104 via DC, UE 102 may send 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 embodiments, MN 106 generates at least one SN message including at least one measurement report and sends at least one SN message to CU 172 in event 507. In one embodiment, the at least one SN message includes RRC transfer Messages and / or SN Modification Request information.

[0205] Upon receiving at least one measurement report (e.g., in response to receiving at least one measurement report) or during communication between SN104 and UE102, SN104 determines to prepare a first cell for UE102, as per the relevant provisions. Figure 3As described. Events 590, 592, 594, 524, 526, 528, 529, 530, 531, 532, 534, 536, 596, 598, or 556 are similar to events 390, 392, 394, 324, 326, 328, 329, 330, 331, 332, 334, 336, 396, 398, or 356, respectively. After receiving the first LTM command 530 (which may include LTM DU configuration and / or TCI state configuration), sending 531 confirmation, and / or determining 532 that UE 102 has successfully connected to the first cell, UE 102, operating in DC mode 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, similar to event 336. At a later time, DU 174 and / or CU 172 may perform LTM execution procedure 598 with UE 102 to request UE 102 to perform a cell change from the first cell to the second cell, similar to procedure 398 or 498. As a result of procedure 598, UE 102, operating in DC mode with MN 106 and SN 104, communicates 556 with DU 174 on the second cell according to LTM DU configuration 2 and communicates 556 with CU 172 via DU 174, similar to event 356.

[0206] Events 504, 506, 505, 507, 590, 592, 594, 524, 526, 528, 529, 530, 531, 532, 534, 536, 596, 598, or 556 are in Figure 5A This is collectively referred to as the "LTM DU configuration and / or activation process" 581.

[0207] Next reference Figure 5B Scenario 500B is largely 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. The RRC reconfiguration messages sent at 517 and 519 are similar to those sent at 316 and 318. The RRC reconfiguration completion messages received at 521 and 523 are similar to those received at 320 and 322. In some embodiments, SN 104 generates a first SN message including the RRC reconfiguration messages (e.g., ...). SN Modification Requirements information, SN modification required beg Message or RRC transmissionIn event 517, MN 106 sends a first SN message to MN 106. MN 106 generates an MN RRC message including an RRC reconfiguration message and sends the MN RRC message described in 519 to UE 102. In response, UE 102 generates an MN RRC response message including an RRC reconfiguration completion message and sends the MN RRC response message described in 521 to MN 106. In some embodiments, MN 106 generates a second SN message including an RRC reconfiguration completion message (e.g., ...). SN reconfiguration complete Message or RRC transmission The message is sent to SN 104 in event 523. In some embodiments, the MN RRC message and the MN RRC response message can be the RRC reconfiguration message and the RRC reconfiguration completion message, respectively.

[0208] Events 504, 506, 505, 507, 590, 592, 594, 517, 519, 521, 523, 524, 526, 528, 529, 530, 531, 532, 534, 536, 596, 598, or 556 are in Figure 5B This is collectively referred to as the "LTM DU configuration and / or activation process" 582.

[0209] Next reference Figure 6A In scenario 600A, the second BS 106 operates as the MN and the first BS 104 operates as the SN, similar to scenarios 300 to 500B. SN 104 includes CU 172, S-DU 174A, and T-DU 174B, similar to the first BS 104 in scenario 400. When UE 102 communicates with MN 106 and SN 104 via DC, MN 106 can perform a 680 LTM DU configuration and / or activation procedure with UE 102, similar to procedures 380 and / or 480. When UE 102 communicates with M-DU 174A and S-DU 174B via DC, CU 172 can perform a 681 LTM DU configuration and / or activation procedure with UE 102 via M-DU 174A or S-DU 174B, similar to procedures 581 or 582.

[0210] Next reference Figure 6B Scenario 600B is similar to scenarios 300 to 500B and 600A, except that SN 104 sends RRC reconfiguration messages 617 and 619 to UE 102 via MN106 and receives RRC reconfiguration completion messages 621 and 623 from UE 102 via MN106.

[0211] Next reference Figure 7AIn scenario 700A, the first BS 104 performs MN and SN operations, similar to scenarios 300 to 600B. The first BS 104 includes CU 172, main DU (M-DU) 174A, and auxiliary DU (S-DU) 174B. CU 172, together with M-DU 174A, performs MN operations, and... Figure 3 The first BS 104 or Figures 5A to 6B Similar to MN 106, and CU 172 together with S-DU 174B as SN operation, and Figures 5A to 6B Similar to SN 104 in the example.

[0212] In scenario 700A, UE 102 initially communicates with M-DU 174A and S-DU 174B via DC 702 and with CU 172 via M-DU 174A and S-DU 174B 702. In event 702, UE 102 uses the serving DU configuration to communicate with S-DU 174B on cell 124A and uses the serving CU configuration to communicate with CU 172 via S-DU 174B, similar to event 302. Events 704 and 706 are similar to events 304 and 306. In some embodiments, UE 102 may send at least one measurement report to M-DU 174A 705, similar to event 304. M-DU 174A then sends at least one DU-to-CU message including at least one measurement report to CU 172 707, similar to event 306. When UE 102 communicates with M-DU 174A and S-DU 174B via DC, CU172 can perform the 780 LTM DU configuration and / or activation procedure with UE 102 via M-DU 174A, similar to procedure 380.

[0213] Events 704, 706, 705, 707, 790, 792, 794, 724, 726, 728, 729, 730, 731, 732, 734, 736, 796, 798, or 756 are in Figure 7A This is collectively referred to as the "LTM configuration and / or activation process" 781.

[0214] Next reference Figure 7B Scenario 700B is similar to scenarios 300 to 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 completion messages from UE 102 via M-DU 174A.

[0215] Events 704, 706, 705, 707, 790, 792, 794, 717, 719, 721, 723, 724, 726, 728, 729, 730, 731, 732, 734, 736, 796, 798, or 756 are in Figure 7B This is collectively referred to as the "LTM DU configuration and / or activation process" 782.

[0216] Next reference Figure 8A In scenario 800A, the first BS 104 operates as both MN and SN, similar to scenarios 300 to 700B. The first BS 104 includes CU 172, primary DU (M-DU) 174A, secondary DU (S-DU) 174B, and target secondary DU (T-DU) 174C. CU 172 operates as MN together with M-DU 174A and as SN together with S-DU 174B. When UE 102 communicates with M-DU 174A and S-DU 174B via DC, CU 172 can perform the 880 LTM DU configuration and / or activation procedure with UE 102 via M-DU 174A, similar to procedure 380. When UE 102 communicates with M-DU 174A and S-DU 174B via DC, CU 172 can perform the 881 LTM DU configuration and / or activation procedure with UE 102 via S-DU 174A, similar to procedure 581 or 582.

[0217] Next reference Figure 8B Scenario 800B is similar to scenarios 300 to 700B and 800A, except that CU 172 sends 817 and 819 RRC reconfiguration messages to UE 102 via M-DU 174A and receives 821 and 823 RRC reconfiguration completion messages from UE 102 via M-DU 174A.

[0218] Next, refer to Figures 9A to 16 B discusses several example methods for supporting TCI-based state-configured LTM that can be implemented in RAN nodes, including DUs and / or CUs. (For...) Figures 3 to 8B The described examples and embodiments can be applied to Figures 9A to 16 The embodiment shown in B or related to Figures 9A to 16 Example B shows a combination of embodiments.

[0219] Figure 9AAn example method 900A for enabling LTM for a UE (e.g., UE 102) is shown, which can be implemented by a CU (e.g., CU 172 of the first BS 104 or the second B 106). Method 900A begins at block 902, where the CU and the first DU perform a first procedure for LTM for the UE (e.g., events 308, 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). In the first process, the CU receives a 904 first LTM DU configuration for configuring the first cell for LTM (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881) from the first DU. The CU sends a 906 first message including the first LTM DU configuration to the UE via the RAN node (e.g., events 316, 318, 394, 380, 480, 494, 580, 594, 581, 517, 519, 582, 680, 694, 681, 617, 619, 780, 794, 781, 717, 719, 880, 894, 881, 817, or 819). The CU and the first DU perform a second procedure for the UE to change the LTM (e.g., events 312, 314, 392, 380, 492, 480, 580, 592, 581, 582, 680, 692, 681, 780, 792, 880, 892, or 881). During the second procedure, the CU receives at least one first TCI state configuration (e.g., events 314, 392, 380, 492, 480, 580, 592, 581, 582, 680, 692, 681, 780, 792, 880, 892, or 881) from the first DU. In some embodiments, each of the first TCI state configurations configures the TCI state for the UE to transmit and / or receive data and / or control signals on the first cell. The CU sends a first TCI state configuration (e.g., events 412, 493, 693, and 893) to the second DU. The CU sends a second message (e.g., events 316, 318, 394, 380, 480, 494, 580, 594, 581, 517, 519, 582, 680, 694, 681, 617, 619, 780, 794, 781, 717, 719, 880, 894, 881, 817, or 819) to the UE via the RAN node. In some embodiments, the CU includes the first TCI state configuration in the LTM configuration IE and includes the LTM configuration IE in the second message. The LTM configuration IE includes the first LTM DU configuration.

[0220] After sending the first message and the second message to the UE, the CU receives from the first DU an indication message 916 indicating that the UE has successfully accessed the first cell (e.g., events 334, 354, 398, 380, 434, 454, 498, 480, 580, 534, 598, 581, 582, 680, 634, 698, 681, 780, 734, 798, 880, 881, 834, or 898). The CU uses the first TCI state configuration to communicate with the UE via the first DU and the first cell 918 (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, or 881).

[0221] In some embodiments, one of the first DU and the second DU is a serving DU, and the other is a target DU (i.e., a candidate DU). In other embodiments, both the first DU and the second DU are target DUs (i.e., candidate DUs). In some embodiments, the RAN node is a serving DU (e.g., the first DU, the second DU, or the third DU), and the CU communicates with the UE via the serving DU and the serving cell operated by the serving DU. In other embodiments, the RAN node is a BS communicating with the UE. For example, the BS is an MN, and the CU is a CU of an SN. In another example, the BS is an SN, and the CU is a CU of an MN.

[0222] In the first process, the CU receives a first DU-to-CU message including a first LTM DU configuration from the first DU. In the second process, the CU receives a second DU-to-CU message including a first TCI state configuration from the first DU. In some embodiments, the first DU generates a service DU configuration (e.g., RRC) including the first TCI state configuration. CellGroupConfig In another embodiment, the first DU includes the first TCI state configuration in the first LTM DU configuration. In yet another embodiment, the first DU includes the first TCI state configuration in both the service DU configuration and the first LTM DU configuration. In the following description, "service DU configuration" or "first LTM DU configuration" may be used instead of "first TCI state configuration".

[0223] In some embodiments, the first DU to CU message and the second DU to CU message are the same message (i.e., the same instance). In other embodiments, the first DU to CU message and the second DU to CU message are separate messages. The first DU to CU message or the second DU to CU message can be... UE Context Establishment Response information, UE context modification response Message or UE context modification requirements The message is as described below. In some embodiments, to identify the first LTM DU configuration and the first TCI state configuration, the first DU to CU message includes the first LTM DU configuration in a first interface protocol IE / field, and the second DU to CU message includes the first TCI state configuration in a second interface protocol IE / field. In some embodiments, the first interface protocol IE / field is a first F1AP IE / field, and the second interface protocol IE / field is a second F1AP IE / field. In some embodiments, one of the first F1AP IE / field and the second F1AP IE / field is... F1AP CellGroupConfig IE / Field And the other one is not F1AP CellGroupConfig IE / Field In other embodiments, neither the first F1AP IE / field nor the second F1AP IE... F1AP CellGroupConfig IE / Field In other embodiments, the second F1AP IE / field is DU CU RRC information IE, and the first F1AP IE / field is a new IE specifically for including LTM DU configuration.

[0224] In some embodiments, the CU sends a third CU-DU message (912) to the second DU, including a first TCI state configuration. If the first TCI state configuration is included in the first LTM DU configuration, the CU includes the first LTM DU configuration in the third CU-DU message. In such cases, the second DU retrieves the first TCI state configuration from the first LTM DU configuration. In some embodiments, the second DU sends a third DU-CU message to the CU in response to the third CU-DU message. In some embodiments, the CU includes either the first TCI state configuration or the first LTM DU configuration in the interface protocol IE / field, and includes the interface protocol IE / field in the third CU-DU message. In some embodiments, the interface protocol field / IE is... CU to DU RRC information IE. In other embodiments, the interface protocol field / IE is F1AP CellGroupConfig IE. In such cases, the CU includes F1APCellGroupConfig IE. CU to DU RRC information In IE, and will CU to DU RRC information The IE is included in the third CU to DU message. In some embodiments, the CU includes an indication that the first TCI state configuration or the first LTM DU configuration is for LTM in the third CU to DU message. In other embodiments, the interface protocol field / IE is a new interface protocol field / IE for LTM. In some embodiments, the new interface protocol field / IE is defined in the 3GPP TS. In some embodiments, the CU includes the new interface protocol field / IE in the third CU to DU message. CU to DU RRC informationIn IE. In other embodiments, CU includes the new interface protocol field / IE. CU to DU RRC information In addition to IE. In some embodiments, the third CU to DU message and the third DU to CU message are respectively UE Context Modification Request Messages and UE context modification response Messages. In other embodiments, the third CU to DU message and the third DU to CU message are respectively UE Context Modification Request Messages and UE context modification requirements Message. In other embodiments, the third CU to DU message and the third DU to CU message are respectively UE Context Establishment Request Messages and UE Context Establishment Response Messages. In some embodiments, the first message and the second message are RRC reconfiguration messages. In some embodiments, the first message and the second message may be combined into a single message, that is, the first message and the second message are the same message. In other embodiments, the first message and the second message are separate messages.

[0225] In some embodiments, the first LTM DU configuration includes a first TCI state configuration, and the CU receives the first TCI state configuration in the first LTM DU configuration. In such embodiments, the CU retrieves the first TCI state configuration from the first LTM DU configuration and includes the first TCI state configuration in a second message. In other embodiments, the first LTM DU configuration includes the first TCI state configuration, and the CU receives the first TCI state configuration in a second DU-CU message. In other words, in addition to including the first TCI state configuration in the first LTM DU configuration, the first DU also includes the first TCI state configuration in the second interface protocol IE / field in the second DU-CU message.

[0226] In some embodiments, the first process is a UE context establishment process or a UE context modification process. The UE context modification process can be initiated by the CU or the first DU. In the case of the UE context establishment process, the CU sends... UE context establishment please beg The message, and in response, receives from the first DU including the configuration of the first LTM DU. UE Context Establishment Response Message. In the case of a UE context modification procedure initiated by the CU, the CU sends... UE Context Modification Request The message, and in response, receives from the first DU including the configuration of the first LTM DU. UE context modification response Message. In the case of a UE context modification procedure initiated by the first DU, the CU receives from the first DU the configuration of the first LTM DU. UE context modification requirements The message is sent, and in response, to the first DU. UE context modification confirmation information.

[0227] In some embodiments, the second process is a UE context establishment process or a UE context modification process. The UE context modification process can be initiated by the CU or the first DU. In the case of a UE context establishment process initiated by the CU, the CU sends... UE The following establishes a request The message, and in response, receives from the first DU a configuration including the first TCI state. UE context establishment response answer Message. In the case of a UE context modification procedure initiated by the CU, the CU sends... UE Context Modification Request Message, and receive from the first DU including the first TCI state configuration UE context modification response Message. In the case of a UE context modification procedure initiated by the first DU, the CU receives from the first DU a message including the first TCI state configuration. UE context modification requirements Message, and send to the first DU UE context modification confirmation information.

[0228] In some embodiments, the first process and the second process can be combined into a single process, that is, the first process and the second process are the same process, and the first DU to CU message and the second DU to CU message are the same DU to CU message (e.g., UE The following establishes a response information, UE context modification response Message or UE context modification requirements Message (as described below). In such cases, the CU receives the first LTM DU configuration and the first TCI state configuration from the first DU during the process. In the case of a UE context establishment procedure initiated by the CU, the CU sends... UE Context Establishment Request The message, and in response, receives from the first DU a configuration including the first LTM DU configuration and the first TCI state configuration. UE Context Establishment Response Message. In the case of a UE context modification procedure initiated by the CU, the CU sends... UE Context Modification Request The message, and receives from the first DU the first LTMDU configuration and the first TCI status configuration. UE context modification response Message. In the case of a UE context modification procedure initiated by the first DU, the CU receives from the first DU a message including the first LTM DU configuration and the first TCI state configuration. UE context modification beg The message is sent, and in response, to the first DU. UE context modification confirmation Message. In some embodiments, the first interface protocol IE / field and the second interface protocol IE / field are included in the parent IE / field of the DU to CU message (e.g., DU to CU RRC InformationIn other embodiments, one of the first interface protocol IE / field and the second interface protocol IE / field is included in the parent IE / field, and the other is not included in the parent IE / field. In yet another embodiment, neither the first interface protocol IE / field nor the second interface protocol IE / field is included in the same parent IE.

[0229] In some embodiments, if the first DU is the target DU (i.e., the first DU is not the serving DU), the CU sends a CU-DU message (e.g., events 412, 493, 693, 893) including the first TCI state configuration to the serving DU (e.g., the second DU or the third DU). In some embodiments, in response, the CU receives a DU-CU message from the serving DU. Otherwise, if the first DU is the serving DU, the CU does not send the first TCI state configuration to the serving DU. In some embodiments, the CU-DU message and the DU-CU message are respectively... UE Context Modification Request Messages and UE context modification response information.

[0230] In some embodiments, each of the first TCI state configurations includes a TCI state ID that identifies the corresponding TCI state configuration. In some embodiments, the serving DU sends a first LTM command to the UE, wherein the first LTM command requests the UE to connect to the first cell (e.g., events 330, 380, 430, 480, 530, 580, 581, 582, 680, 681, 630, 780, 730, 880, 881, or 830). Upon receiving the first LTM command (e.g., in response to receiving the first LTM command), the UE disconnects from the serving cell operated by the serving DU and connects to the first cell and communicates with the first DU on the first cell (e.g., events 336, 380, 436, 480, 536, 580, 581, 582, 636, 680, 681, 736, 780, 836, 880, or 881). In some embodiments, the first TCI state configuration includes TCI state configurations 1, ..., L, where L is a positive integer greater than zero. TCI state configurations 1, ..., L may include TCI state IDs 1, ..., L, respectively identifying TCI state configurations 1, ..., L. The serving DU includes TCI state ID 1 in a first LTM command to request the UE to apply TCI state configuration 1 to communicate on the first cell. Upon receiving the first LTM command (e.g., in response to receiving the first LTM command), the UE uses TCI state configuration 1 based on TCI state ID 1 to access the first cell and / or communicate on the first cell. In some embodiments, the first DU detects UE access to the first cell and communication with the UE on the first cell based on TCI state configuration 1.

[0231] In some embodiments, in addition to TCI State ID 1, the serving DU also includes TCI State ID 2 in the first LTM command to instruct the UE to apply TCI State Configuration 2 to communicate on the first cell. Upon receiving the first LTM command (e.g., in response to receiving the first LTM command), the UE uses TCI State Configurations 1 and 2 to access the first cell and / or communicate on the first cell based on TCI State ID 1 and TCI State ID 2. In some embodiments, the first DU detects the UE's access to the first cell and communicates with the UE on the first cell based on TCI State Configuration 1 and TCI State Configuration 2. For example, upon receiving the first LTM command (e.g., in response to receiving the first LTM command), the UE may skip the random access procedure and directly transmit a first transmission (e.g., a PUSCH transmission or a PUCCH transmission) on the first cell using the first TCI State Configuration. The first DU receives the first transmission from the UE on the first cell using the first TCI State Configuration.

[0232] In some alternative embodiments, the serving DU may not include the TCI state ID in the first LTM command, and after receiving the first LTM command (e.g., in response to receiving the first LTM command), the UE uses at least one first TCI state to communicate with the first DU on the first cell. In some embodiments, the first DU detects UE access to the first cell and communicates with the UE on the first cell based on the first TCI state configuration. For example, in response to receiving the first LTM command, the UE may skip the random access procedure and directly send a first transmission (e.g., a PUSCH transmission or a PUCCH transmission) to DU 174 on the first cell. The first DU uses the first TCI state configuration to receive the first transmission from the UE.

[0233] In some embodiments, the serving DU includes a first ID identifying the first cell or the first LTM configuration in the first LTM command, where the first ID may be a first cell ID, a first cell index, or a first LTM ID. In some embodiments, the serving DU receives the ID and / or the first LTM DU configuration from the CU. In some embodiments, the serving DU includes a timing advance value in the first LTM command. In some embodiments, before sending the first LTM command, the serving DU sends a DCI (e.g., a PDCCH command) to the UE on the serving cell to instruct the UE to send a preamble (e.g., a random access preamble) on the first cell. After the DCI (e.g., in response to the DCI), the UE sends the preamble on the first cell. The first DU determines the timing advance value by measuring the time taken for the first DU to receive the preamble (i.e., the propagation delay). After receiving the first LTM command (e.g., in response to receiving the first LTM command), the UE disconnects from the serving cell and accesses the first cell using the timing advance value. After receiving the first LTM command (e.g., in response to receiving the first LTM command), the UE applies the timing advance value to the first DU in one or more uplink transmissions on the first cell.

[0234] In some embodiments, before sending the first LTM command, the serving DU may send one or more activation commands to activate TCI state configurations 1, ..., K, where K is a positive integer and 1 ≤ K ≤ L. For example, K is 1 or 2. In another example, K equals L. Upon receiving the activation command, the UE determines that TCI state configurations 1, ..., K are activated. In some embodiments, each of the activation commands is a MAC CE. In other embodiments, each of the activation commands is a DCI. In some embodiments, the serving DU includes or indicates TCI state IDs 1, ..., K in the activation command. In some embodiments, when the serving DU determines to send an LTM command (e.g., a first LTM command) for the UE to instruct the UE to perform a fast service change to a target cell (e.g., a first cell), the serving DU includes only one or more TCI state IDs (e.g., one, some, or all of TCI state IDs 1, ..., K) of one or more TCI state configurations (e.g., TCI state configurations 1, ..., K) that the serving DU has already activated for the UE in the LTM command (e.g., the first LTM command). In some embodiments, the serving DU avoids including TCI state IDs of TCI state configurations that the serving DU has not yet activated for the UE in the LTM command for the UE. In some embodiments, DU174 includes a first cell ID or a first cell index in the activation command. Based on the first cell ID or the first cell index and one or more TCI state IDs in the activation command, the UE determines that the activation command activates one or more TCI state configurations in the first TCI state configurations, wherein each of the TCI state IDs identifies a specific TCI state configuration in the TCI state configurations.

[0235] In some embodiments, the first LTM DU configuration includes a first TCI state configuration, and the CU receives the first TCI state configuration in a (second) DU-CU message. In some embodiments, in addition to including the first TCI state configuration in the first LTM DU configuration, the first DU also includes the first TCI state configuration in the (second) Interface Protocol (IE) / field of the (second) DU-CU message. After detecting UE access to the first cell, the first DU performs PUSCH, PDSCH, PUCCH, PDCCH, and / or SRS transmissions with the UE. In some embodiments, the first DU uses the first TCI state configuration to perform communication with the UE. In some embodiments, the first DU includes additional TCI state configurations in the first LTM DU configuration. In some embodiments, the first DU uses some or all of the additional TCI state configurations to perform PUSCH, PDSCH, PUCCH, PDCCH, and / or SRS transmissions with the UE.

[0236] In some embodiments, the CU and the first DU perform a third procedure for LTM for the UE, and in the third procedure, the CU receives at least one first RS resource configuration from the first DU. In the third procedure, the CU receives a third DU-to-CU message from the first DU including the first RS resource configuration. In some embodiments, the third procedure may be a UE context establishment procedure or a UE context modification procedure, as described above, and the third DU-to-CU message is... UE Context Establishment Response information, UE context modification response Message or UE context modification requirements Message. In some embodiments, each of the first RS resource configurations configures one or more RSs and / or one or more RS resources. An RS may be an SSB or a CSI-RS. In some embodiments, each of the first RS resource configurations is an NZP-CSI-RS-Resource IE, an NZP-CSI-RS-ResourceSet IE, and / or a CSI-SSB-ResourceSet IE.

[0237] In some embodiments, the CU sends a fourth CU-DU message to the second DU including at least one first RS resource configuration. Based on at least one first RS resource configuration, the second DU generates at least one first reporting configuration for reporting measurement results of RS or RS resources. In some embodiments, the first reporting configuration configures UL resources (e.g., PUCCH resources or PUSCH resources) for the transmission of measurement results. In some embodiments, each of the measurement results includes an RS resource indicator and / or a quantized measurement value. The RS resource indicator is an SSB resource indicator or a CSI-RS resource indicator. The quantized measurement value may be L1-RSRP or L1-SINR. The second DU sends a fourth DU-CU message to the CU including the first reporting configuration. Then, the CU sends a third message including the first reporting configuration to the UE 102 via the serving DU or RAN node. In some embodiments, each of the first reporting configurations includes a resource configuration ID that identifies a specific RS resource configuration among at least one first RS resource configuration. In some embodiments, each of the first reporting configurations is CSI-ReportConfig IE. In some embodiments, the first report configuration is similar to the L1 measurement report configuration described above. In some embodiments, the CU includes the first RS resource configuration in a third message.

[0238] In some other embodiments, the second DU includes the first report configuration in the DU configuration (e.g., RRC). CellGroupConfig In IE), the DU configuration is included in the fourth DU to CU message. In some embodiments, the fourth CU to DU message is UE Context Modification Request The message, and the fourth DU to CU message is UE context modification response Message or UE Context modification requirements In some embodiments, the second DU includes the first RS resource configuration in the DU configuration. In other embodiments, the serving DU does not include the first RS resource configuration in the serving DU configuration. In some embodiments, the second DU includes the DU configuration in the fourth DU to CU message. DU to CU RRC information In the IE. For example, the second DU includes the service DU configuration in the interface protocol IE / field (e.g., F1AP CellGroupConfig IE / field) and the interface protocol UE / field in the fourth DU to CU message. After receiving the fourth DU to CU message, the CU sends a third message including the DU configuration to UE 102 via the service DU or RAN node. In some embodiments, if the second DU is a service DU, the DU configuration is the service DU configuration, and the CU includes the service DU configuration in the third message. The CU avoids including the service DU configuration in the LTM configuration. In other embodiments, if the second DU is not a service DU (e.g., the second DU is a target DU), the DU configuration is the (second) LTM DU configuration, and the CU includes the LTM DU configuration in the LTM configuration in the third message. In the following description, "service DU configuration" or "(second) LTM DU configuration" may be used instead of "first report configuration".

[0239] In some embodiments, the third message is an RRC reconfiguration message similar to the RRC reconfiguration message in events 316, 318, 394, 380, 480, 494, 580, 594, 581, 517, 519, 582, 680, 694, 681, 617, 619, 780, 794, 781, 717, 719, 880, 894, 881, 817, or 819. In other embodiments, the third message is an RRC reconfiguration message in events 316, 318, 394, 380, 480, 494, 580, 594, 581, 517, 519, 582, 680, 694, 681, 617, 619, 780, 794, 781, 717, 719, 880, 894, 881, 817, or 819.

[0240] In some alternative embodiments, the CU receives the first RS resource configuration from the first DU in a first process or a first DU to CU message. In some embodiments, the first DU includes the first RS resource configuration in a first LTM DU configuration. In some embodiments, the CU may receive the first RS resource configuration in the first LTM DU configuration. In some embodiments, the first DU includes the first LTM DU configuration in a first interface protocol IE / field and includes the first RS resource configuration in a second interface protocol IE / field in the first DU to CU message.

[0241] In other alternative embodiments, the CU receives the first RS resource configuration from the first DU in a second process or a second DU-to-CU message. In some embodiments, the first DU includes the first TCI status configuration and the first RS resource configuration in the second interface protocol IE / field of the first DU-to-CU message. In other embodiments, the first DU includes the first TCI status configuration and the first RS resource configuration in the second interface protocol IE / field and the third interface protocol IE / field (e.g., F1AP IE / field), respectively, of the first DU-to-CU message. In some alternative embodiments, the CU includes the first RS resource configuration and / or the first report configuration in the first message. In other alternative embodiments, the CU includes the first RS resource configuration and / or the first report configuration in the second message.

[0242] In some embodiments, if the first DU is a target DU (i.e., the first DU is not a serving DU), the CU sends a first TCI status configuration to the serving DU (e.g., the second DU). Otherwise, if the first DU is a serving DU, the CU does not send the first TCI status configuration to the first DU. In some embodiments, if the first DU is a target DU (i.e., the first DU is not a serving DU), the CU sends at least one first RS resource configuration to the serving DU (e.g., the second DU). Otherwise, if the first DU is a serving DU, the CU does not send at least one first RS resource configuration to the first DU. In some embodiments, the serving DU and the first DU are respectively... Figure 4 , Figure 6A and Figure 6B The S-DU 174A and T-DU 174B are mentioned. In some embodiments, the service DU and the first DU are respectively... Figure 8A and Figure 8B The S-DU 174B and T-DU 174C are among them.

[0243] In some embodiments, the CU receives a first additional LTM DU configuration and at least one first additional TCI state configuration from the first DU in a first DU-CU message and a second DU-CU message, respectively. In other embodiments, the CU performs one or more additional procedures with the first DU, similar to the first procedure and / or the second procedure. In these additional procedures, the CU receives one or more additional DU-CU messages from the first DU, similar to the first DU-CU message and / or the second DU-CU message, including the first additional LTM DU configuration and at least one first additional TCI state configuration. The first additional LTM DU configuration configures a first additional cell for the UE for LTM. In some embodiments, the CU includes the first additional LTM DU configuration and at least one first additional TCI state configuration in a first message and a second message, respectively. Alternatively, the CU includes the first additional LTM DU configuration and at least one first additional TCI state configuration in a first message. Alternatively still, the CU sends one or more additional messages including the first additional LTM DU configuration and at least one first additional TCI state configuration to the UE via the RAN node. In some embodiments, the additional message is an RRC reconfiguration message. In some embodiments, the CU sends at least one first additional TCI state configuration to the second DU and / or the serving DU. In one embodiment, the CU includes at least one first additional TCI state configuration in a third CU-DU message. In another embodiment, the CU sends a fourth CU-DU message to the second DU and / or the serving DU, which includes at least one first additional TCI state configuration, similar to the third CU-DU message. When the first DU (i.e., the serving DU) communicates with the UE on the first cell 918, the first DU may send an additional LTM command to the UE, wherein the additional LTM command requests the UE to connect to the first additional cell (e.g., events 350, 398, 380, 450, 498, 480, 598, 580, 581, 582, 680, 681, 698, 780, 798, 880, 881, or 898). Upon receiving an additional LTM command (e.g., in response to receiving an additional LTM command), the UE disconnects from the first cell and connects to the first additional cell, communicating with the first DU on the first additional cell (e.g., events 356, 380, 456, 480, 556, 580, 581, 582, 656, 680, 681, 756, 780, 856, 880, or 881). In some embodiments, at least one first additional TCI state configuration includes TCI state configurations L+1, ..., L+M, where L and M are positive integers. The TCI state configurations L+1, ..., L+M include TCI state IDs L+1, ..., L+M that respectively identify the TCI state configurations L+1, ..., L+M.The first DU includes TCI state ID L+1 in an additional LTM command to instruct the UE to apply TCI state configuration L+1 for communication on the first additional cell. In response to the additional LTM command, the UE communicates on the first additional cell using TCI state configuration L+1 based on TCI state ID L+1. In some embodiments, in addition to TCI state ID L+1, the first DU also includes TCI state ID L+2 in the additional LTM command to request the UE to apply TCI state configuration L+2 for communication on the first additional cell. In such cases, after receiving the additional LTM command (e.g., in response to receiving the additional LTM command), the UE communicates with the first DU on the first additional cell using TCI state configurations L+1 and L+2 based on TCI state ID L+1 and TCI state ID L+2. In some embodiments, the first DU may not include the TCI state ID (e.g., TCI state ID 1) in the additional LTM command, and after receiving the additional LTM command (e.g., in response to receiving the additional LTM command), the UE communicates with the first DU on the first additional cell using at least one first additional TCI state. In some embodiments, the first DU includes an additional ID that identifies the first additional cell or the first additional LTM configuration in the additional LTM command, wherein the additional ID may be an additional cell ID, an additional cell index, or an additional LTM ID. In some embodiments, the first DU receives the additional ID from the CU.

[0244] In some embodiments, before sending an additional LTM command, the first DU may send one or more activation commands to activate TCI state configurations L+1, ..., L+N, where N is a positive integer and 1 ≤ N ≤ M. For example, N is 1 or 2. After receiving the activation command (e.g., in response to receiving the activation command), the UE activates the TCI state configurations L+1, ..., L+N. In some embodiments, each of the activation commands is a MAC CE. In other embodiments, each of the activation commands is a DCI. In some embodiments, the first DU includes or indicates TCI state IDs L+1, ..., L+N in the activation command. In some embodiments, when the first DU determines to send an LTM command for the UE to request the UE to perform a fast service change / handover to a target cell (e.g., a first additional cell), the first DU includes only one, some, or all of the one or more TCI state configurations (e.g., one, some, or all of TCI state configurations L+1, ..., L+N) that the first DU has already activated for the UE in the LTM command (e.g., an additional LTM command). In other words, the first DU avoids including or indicating in the LTM command for the UE a TCI state ID that the first DU has not yet configured for the TCI state activated for the UE.

[0245] In some embodiments, the CU receives a second additional LTM DU configuration and at least one second additional TCI state configuration from a second DU or a third DU. The third LTM DU configuration configures the second additional cell for the UE for the LTM. The CU sends the second additional LTM DU configuration and at least one second additional TCI state configuration to the UE, similar to blocks 902 to 910 and 914. The CU may send at least one second additional TCI state configuration to a first DU and / or other DUs, similar to block 912. The CU may then receive an indication message from the second DU or third DU indicating that the UE has successfully accessed the second additional cell, similar to block 916. The CU communicates with the UE via the second DU or third DU and the second additional cell, similar to block 918.

[0246] In some embodiments, each of the TCI state configurations described above associates one or two DL RSs with a corresponding QCL type. DL RSs are transmitted on the cell. Each TCI state configuration includes QCL information IE (e.g., for QCL type 1). In some embodiments, each TCI state configuration also includes additional QCL information IE (e.g., for QCL type 2) and / or an additional Physical Cell Identifier (PCI) index. In some embodiments, each TCI state configuration also configures UL power control configuration and / or path loss RS. For example, each TCI state configuration includes a UL power control ID and a path loss RS ID, respectively identifying the UL power control configuration and / or the path loss RS. QCL information includes configurations such as a serving cell index, a bandwidth portion (BWP) ID, an RS ID, and / or a QCL type. The RS ID indicates the RS associated with the QCL information. In some embodiments, the RS ID is a CSI-RS ID (e.g., NZP-CSI-RS-ResourceId), and the RS can be a CSI-RS (e.g., NZP-CSI-RS-Resource) indicated by the CSI-RS ID. In other embodiments, the RS ID is an SSB index, and the RS is the SSB indicated by the SSB index. The serving cell index indicates the cell in which the RS is configured. The BWP ID indicates the BWP where the RS resides. The BWP belongs to the cell. The cell is a first cell in a first TCI state configuration. The cell is a first additional cell in at least one first supplementary TCI state configuration. The cell is a second additional cell in at least one second supplementary TCI state configuration. The QCL type is type A, type B, type C, or type D. In some embodiments, each TCI state configuration includes a TCI state ID as described above for identifying each TCI state configuration. Supplementary QCL information includes configurations similar to those described above, and these configurations have values ​​different from the QCL information. For example, the QCL information and the supplementary QCL information have the same RS ID (value) and different QCL types in the TCI state configuration. In some embodiments, at least one (first, first supplementary, or second supplementary) TCI state configuration includes ul-TCI-ToAddModList-r17 Fields, one or more TCI- UL-State-r17 IE dl-OrJointTCI-StateToAddModList-r17 Fields, one or more TCI-State IE TCI-ActivatedConfig IE and / or tci-StatesToAddModList Field.

[0247] Figure 9BThis is a flowchart of an example method 900B, similar to method 900A, except that method 900B includes blocks 913 and 915 instead of block 914. The CU receives at least one second TCI state configuration from the second DU at 913. In some embodiments, the CU receives a DU-to-CU message (e.g., event 414, 493, 693, or 893) from the second DU that includes the second TCI state configuration. The DU-to-CU message is related to... Figure 9A The third DU to CU message described herein is similar. In some embodiments, the second DU is as described for... Figure 9A The service DU described in the embodiments. In other embodiments, the second DU is not as described for... Figure 9A The described service DU. The CU sends a second message (e.g., events 316, 318, 394, 380, 480, 494, 580, 594, 581, 517, 519, 582, 680, 694, 681, 617, 619, 780, 794, 781, 717, 719, 880, 894, 881, 817, or 819) to the UE via the RAN node. In some embodiments, the CU includes the second TCI state configuration in a non-LTM field in the second message (e.g., masterCellGroup field or secondaryCellGroup In the field).

[0248] In some embodiments, the second DU generates a second TCI state configuration based on a first TCI state configuration. In some embodiments, the second DU retrieves each TCI state configuration (e.g., QCL information, additional QCL information, PCI index, UL power control ID, and / or path loss RS ID) from the first TCI state configuration and includes each TCI state configuration in the second TCI state configuration. In each TCI state configuration within the second TCI state configuration, the second DU assigns a value to a TCI state ID and includes the TCI state ID in the corresponding TCI state configuration. In some embodiments, the second DU does not use the value of the TCI state ID from the first TCI state configuration.

[0249] like Figure 9AAs described, the second DU receives 912 a first LTM DU configuration including a first TCI state configuration from the CU. In some embodiments, the second DU decodes the first LTM DU configuration to obtain the first TCI state configuration and retrieves each TCI state configuration from the first TCI state configuration. In some embodiments, the second DU generates a second TCI state configuration including each TCI state configuration in the first TCI state configuration. In some embodiments, the second DU generates the same second TCI state configuration as the first TCI state configuration. In other embodiments, the second DU generates the second TCI state configuration based on the first TCI state configuration, as described above.

[0250] In some embodiments, the second DU may generate a DU configuration including a second TCI state configuration and send the DU configuration to the CU. In some embodiments, the second DU includes the DU configuration in a DU-to-CU message. In some embodiments, the DU configuration is an RRC IE (e.g., an RRC as defined in 3GPP TS 38.331). CellGroupConfig (IE). In some embodiments, if the second DU is a service DU, then the DU configuration is a service DU configuration, and the CU includes the service DU configuration in the second message. The CU avoids including the service DU configuration in the LTM configuration. In other embodiments, if the second DU is not a service DU (e.g., the second DU is a target DU), then the DU configuration is a (second) LTM DU configuration, and the CU includes the LTM DU configuration in the LTM configuration in the second message.

[0251] Figure 10 An example method 1000 for sending TCI state configuration to a DU to enable LTM for a UE (e.g., UE 102) is shown, which can be implemented by a CU (e.g., CU 172 of the first BS 104 or the second BS 106).

[0252] Method 1000 begins with the CU receiving, 1002, at least one first TCI state configuration for the UE from a first DU (e.g., events 314, 392, 380, 492, 480, 580, 592, 581, 582, 680, 692, 681, 780, 792, 880, 892, or 881). The CU determines, 1004, whether the first DU is communicating with the UE. If the CU determines that the first DU is not communicating with the UE (i.e., the first DU is not the UE's serving DU), the CU sends, 1006, the first TCI state configuration to the UE's serving DU (e.g., events 412, 493, 693, or 893). Otherwise, if the CU determines that the first DU is communicating with the UE (i.e., the first DU is the UE's serving DU), the CU avoids sending, 1008, the first TCI state configuration to the serving DU. Figure 9A and Figure 9B The description can be applied to Figure 10 .

[0253] Figure 11 It shows that it can be generated by the first DU (e.g., Figures 3 to 8B Example method 1100 for enabling LTM for a UE (e.g., UE 102) implemented in the first BS 104 or the second BS 106 (DU174, 174A, 174B or 174C).

[0254] Method 1100 begins with the first DU and CU performing a first procedure for LTM (e.g., events 308, 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881) for the UE. During the first procedure, the first DU sends a first LTM DU configuration (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881) to the CU (1104). The first DU then sends a first LTM DU configuration (1106) to the UE. In some embodiments, the first DU receives a first message including the configuration of the first LTM DU from the CU and sends a first message to the UE (e.g., events 316, 318, 394, 380, 580, 594, 581, 582, 780, 794, or 781). The first DU and the CU perform a second procedure for LTM 1108 for the UE (e.g., events 312, 314, 392, 380, 492, 480, 580, 592, 581, 582, 680, 692, 681, 780, 792, 880, 892, or 881). In the second process, the first DU sends at least one first TCI state configuration (e.g., events 314, 392, 380, 492, 480, 580, 592, 581, 582, 680, 692, 681, 780, 792, 880, 892, or 881) to the CU. In some embodiments, each of the first TCI state configurations configures the TCI state for the UE to transmit and / or receive data and / or control signals on the first cell. The first DU sends the first TCI state configuration to the UE. In some embodiments, the first DU receives a second message from the CU including the first TCI state configuration and sends a second message to the UE (e.g., events 316, 318, 394, 380, 580, 594, 581, 582, 780, 794, or 781). The first DU detects UE access to 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, or 898). In some embodiments, the first DU detects UE access to the first cell based on one, some, or all of the first TCI state configuration.The first DU sends an indication message 1116 to the CU indicating that the UE has successfully accessed the first cell (e.g., events 334, 354, 398, 380, 434, 454, 498, 480, 580, 534, 598, 581, 582, 680, 634, 698, 681, 780, 734, 798, 880, 881, 834, or 898). The first DU uses a first TCI state configuration to communicate 1118 with the UE via 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, or 881).

[0255] against Figure 9A and Figure 9B The described examples and embodiments can be applied to Figure 11 .

[0256] Figure 12A This shows that it can be generated by DU (e.g., Figures 3 to 8B Example method 1200A for enabling LTM for a UE (e.g., UE 102) is implemented in the first BS 104 or the second BS 106 (DU174, 174A, 174B or 174C).

[0257] Method 1200A begins with the DU communicating with the UE and CU at 1202 (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, 780, 880, or 881). The DU receives from the CU at 1204 a request to prepare a first CU-DU message for the first cell for the UE in relation to LTM (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). The DU generates at 1206 a first LTM DU configuration for the first cell. The DU generates at 1208 at least one first TCI state configuration for configuring at least one TCI state. The DU sends a first DU-to-CU message (e.g., event 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881) to the CU, which includes a first LTM DU configuration and at least one first TCI state configuration.

[0258] The DU sends command 1212 to the UE, which is the first LTM command for the UE to use the LTM procedure to switch to the first cell. The DU detects 1214 indicating that the UE has accessed the first cell (e.g., events 332, 336, 352, 356, 380, 432, 436, 452, 456, 498, 480, 532, 536, 552, 598, 556, 580, 581, 582, 632, 636, 698, 656, 680, 681, 732, 736, 798, 756, 780, 832, 836, 898, 868, 880, or 881). In some embodiments, the DU uses one or more of the first TCI state configurations to detect that the UE has accessed the first cell. The DU sends a 1216 indication message to the CU indicating that the UE has successfully accessed the first cell (e.g., events 334, 354, 380, 398, 434, 454, 498, 480, 534, 598, 580, 581, 582, 734, 798, 780, 834, 898, 880, or 881). The DU uses the first TCI state configuration to communicate with the UE via the first cell 1218 (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, or 881).

[0259] In some embodiments, the DU includes the first LTM DU configuration in the first interface protocol IE or field (IE / field) of the first DU to CU message. In some embodiments, the DU includes the first TCI status configuration in the second interface protocol IE / field of the first DU to CU message. In some embodiments, one of the first interface protocol IE / field and the second interface protocol IE / field is F1AP. CellGroupConfig IE / field, and another with F1AP CellGroupConfig The IE / fields are different. In other embodiments, one of the first interface protocol IE / fields and the second interface protocol IE / fields is... DU CU RRC information IE / field, and another with DU to CU RRC information The IE / fields are different. The DU includes the first LTM DU configuration and the first TCI state configuration in different interface protocol IE / fields, allowing the CU to retrieve or identify the first LTM DU configuration and the first TCI state configuration from the first interface protocol IE / fields and the second interface protocol IE / fields, respectively. Therefore, the CU can correctly send the first LTM DU configuration and the first TCI state configuration to the UE, such as... Figure 9A As described.

[0260] In other embodiments, the DU includes the first LTM DU configuration and the first TCI state configuration in the interface protocol IE / field of the first DU to CU message. In some embodiments, the DU includes the first LTM DU configuration and the first TCI state configuration in a first sub-IE / field and a second sub-IE / field, respectively, and includes both the first and second sub-IE / fields in the interface protocol IE / field of the first DU to CU message. The DU includes the first LTM DU configuration and the first TCI state configuration in different sub-IE / fields, allowing the CU to retrieve or identify the first LTM DU configuration and the first TCI state configuration from the first and second sub-IE / fields, respectively. Therefore, the CU can correctly send the first LTM DU configuration and at least one first reference signal resource configuration to the UE, such as... Figure 9A As described.

[0261] In some embodiments, the first CU to DU message and the first DU to CU message are UE Context Establishment Request Messages and UE Context Establishment Response Messages. In other embodiments, the first CU to DU message and the first DU to CU message are... UE context Modification Request Messages and UE context modification response Message. In yet another embodiment, the first CU to DU message and the first DU to CU message are UE Context Modification Request Messages and UE context modification requirements Message. In such cases, DU responds to UE Request for amendments Send message to CU UE context modification response Message, and DU responds UE context modification requirements Message received from CU UE context modification confirmation information.

[0262] In some embodiments, the DU receives a second CU-to-DU message from the CU requesting preparation of a second cell for the UE in response to LTM (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). In such cases, the DU generates a second LTM DU configuration for the second cell and generates at least one second TCI state configuration for at least one second TCI state. The DU sends a second DU-to-CU message to the CU including the second LTM DU configuration and the second TCI state configuration (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).

[0263] Figure 12BThis is a flowchart of an example method 1200B, similar to method 1200A, except that method 1200B includes blocks 1209 and 1211 instead of block 1210. DU sends a first DU-to-CU message 1209, including a first LTM DU configuration (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). DU sends an additional DU-to-CU message 1210, including at least one TCI status configuration. Figure 12A Unlike the first DU, the DU will include at least one first TCI state configuration in the appended DU to CU message instead of the first DU to CU message.

[0264] In some embodiments, the DU includes the first LTM DU configuration in the first interface protocol IE or field (IE / field) of the first DU to CU message. In some embodiments, the DU includes the first TCI status configuration in the second interface protocol IE / field of the appended DU to CU message. In some embodiments, one of the first interface protocol IE / field and the second interface protocol IE / field is F1AP. CellGroupConfig IE / field, and another with F1AP CellGroupConfig The IE / fields are different. In other embodiments, one of the first interface protocol IE / fields and the second interface protocol IE / fields is... DU CU RRC information IE / field, and another with DU to CU RRC information The IE / fields are different. The DU includes the first LTM DU configuration and the first TCI state configuration in different interface protocol IE / fields, allowing the CU to retrieve or identify the first LTM DU configuration and the first TCI state configuration from the first interface protocol IE / fields and the second interface protocol IE / fields, respectively. Therefore, the CU can correctly send the first LTM DU configuration and at least one first reference signal resource configuration to the UE, as for... Figures 9A to 9B As described.

[0265] against Figure 9A , Figure 9B and Figure 11 The examples and embodiments described in the DU (e.g., service DU, first DU, or second DU) can be applied to Figure 12A and Figure 12B DU in the middle.

[0266] Figure 13A This shows that it can be generated by DU (e.g., Figures 3 to 8B Example method 1300A for enabling LTM for a UE (e.g., UE 102) is implemented using DU 174, 174A, 174B or 174C.

[0267] Method 1300A begins with the DU receiving 1302 at least one first TCI state configuration from the CU, wherein each of the at least one first TCI state configuration configures a TCI state (e.g., events 308, 390, 380, 312, 392, 490, 492, 480, 580, 590, 592, 581, 582, 680, 690, 692, 681, 780, 790, 792, 880, 890, 892, or 881). In some embodiments, the DU receives a CU-DU message from the CU including the first TCI state configurations. In some embodiments, each of the first TCI state configurations configures a TCI state for communication on a cell of another DU (e.g., a T-DU). The DU generates 1304 at least one second TCI state configuration based on the at least one first TCI state configuration. The DU sends at least one second TCI state configuration (e.g., events 310, 390, 380, 314, 392, 490, 492, 480, 580, 590, 592, 581, 582, 680, 690, 692, 681, 780, 790, 792, 880, 890, 892, or 881) to the CU. In some embodiments, the DU sends a DU-CU message including the second TCI state configuration to the CU. The DU sends a 1308 first LTM command to the UE, instructing the UE to connect to the first cell. The first LTM command includes a first TCI state ID (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, or 898) identifying the first TCI state configuration. In some embodiments, the DU may include a second TCI ID identifying the second TCI state configuration in the first LTM command.

[0268] In some embodiments, the CU to DU message and the DU to CU message are respectively UE Context Establishment Request Messages and UE The following establishes a response Messages. In other embodiments, CU-to-DU messages and DU-to-CU messages are respectively UE Context Modification Request Messages and UE context modification response Message. In some alternative embodiments, the DU to CU message is UE context modification requirementsIn some embodiments, the DU includes an LTM ID that identifies the LTM configuration in the first LTM command. In one embodiment, the LTM ID is the cell ID of the first cell. In another embodiment, the LTM ID is a cell index indexed to the first cell. In yet another embodiment, the LTM ID is an ID that identifies the LTM configuration used for communication via the first cell.

[0269] In some embodiments, the CU includes the first TCI state configuration in the new IE / field, and also includes the new IE / field in the CU-DU message. In some embodiments, the CU includes the new IE / field in... CU to DU RRC information In IE, and will CU to DU RRC information The IE is included in the CU to DU message. In other embodiments, the CU does not include the new IE / field. CU to DU RRC Information In the IE. In some embodiments, the CU includes the first TCI state configuration in the new IE / field, and includes the new IE / field in the CU to DU message. In other embodiments, the DU receives 1302 from the CU including the DU configuration (e.g., RRC). CellGroupConfi The CU to DU message (g IE) includes a first TCI state configuration. In some embodiments, the CU includes the DU configuration in... CU to DU RRC information In IE, and will CU to DU RRC information IE is included in the CU to DU message.

[0270] In some embodiments, the DU includes the second TCI state configuration in the interface protocol IE / field of the DU-CU message. In some embodiments, the interface protocol IE / field is a new IE / field that differs from the F1APCellGroupConfig IE / field defined in 3GPP TS 38.473. In other embodiments, the DU includes the second TCI state configuration in the service DU configuration and sends a 1306 service DU configuration to the CU. In some embodiments, the service DU configuration is a cell group configuration (e.g., RRC) that includes configuration parameters for communication between the UE and the DU. CellGroupConfig (IE). In some embodiments, the DU sends a DU-to-CU message (1306) including the service DU configuration to the CU.

[0271] Figure 13BThis is a flowchart of an example method 1300B, similar to method 1300A, except that method 1300B includes block 1307 instead of blocks 1304, 1306, and 1308. The DU sends block 1307 to the UE, instructing the UE to connect to the first cell, wherein the first LTM command includes a first TCI state ID identifying the first TCI state configuration. In some embodiments, the DU may include a second TCI state ID identifying the second TCI state configuration in the first LTM command.

[0272] against Figure 9A , Figure 9B and Figures 11 to 12B The examples and embodiments described in the DU (e.g., service DU, first DU, or second DU) can be applied to Figure 13A and Figure 13B DU in the middle.

[0273] Figure 14A This shows that it can be generated by DU (e.g., Figures 3 to 8B Example method 1400A for enabling LTM for a UE (e.g., UE 102) is implemented using DU 174, 174A, 174B or 174C.

[0274] Method 1400A begins with the DU receiving a first CU-DU message from the CU requesting preparation of a first cell for the UE in response to LTM, wherein the first CU-DU message includes at least one first TCI state configuration, and each of the first TCI state configurations configures a TCI state (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). In some embodiments, each of the TCI states associates one or two DL RSs with a corresponding QCL type and a cell other than the first cell. The DU generates at least one second TCI state configuration based on the first TCI state configuration, at step 1404. The DU generates a first LTM DU configuration for the UE to use the LTM procedure to hand over to the first cell, at step 1406. The first LTM DU configuration may include the second TCI state configuration. The DU sends a 1408 message to the CU, which includes the first LTM DU configuration and the second TCI state configuration (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).

[0275] In some embodiments, the DU retrieves each TCI state configuration (e.g., QCL information, additional QCL information, PCI index, UL power control ID, and / or path loss RS ID) from a first TCI state configuration and includes each TCI state configuration in a second TCI state configuration. In each TCI state configuration within the second TCI state configuration, the DU assigns a value to a TCI state ID and includes the TCI state ID in the corresponding TCI state configuration. In some embodiments, the DU does not use the value of the TCI state ID from the first TCI state configuration.

[0276] In some embodiments, the DU receives a second CU-DU message from the CU requesting the preparation of a second cell for the UE using LTM, wherein the second CU-DU message includes a first TCI state configuration (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). The DU generates at least one third TCI state configuration based on the first TCI state configuration. The DU generates a second LTM DU configuration for the UE to configure the second cell. The second LTM DU configuration may include the third TCI state configuration. The DU sends a second DU-CU message to the CU including the second LTM DU configuration and the third TCI state configuration (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).

[0277] Figure 14B This is a flowchart of an example method 1400B, similar to method 1400A, except that method 1400B includes block 1405 instead of blocks 1404 and 1406. The DU generates a first LTM DU configuration for the UE, including a first TCI state configuration, in block 1405.

[0278] In some embodiments, the DU receives a second CU-DU message from the CU requesting the preparation of a second cell for the UE using LTM, wherein the second CU-DU message includes a first TCI state configuration (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). The DU generates a second LTM DU configuration for the UE to configure the second cell. The DU sends a second DU-CU message to the CU including the second LTM DU configuration and the first TCI state configuration (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881).

[0279] against Figure 9A , Figure 9B and Figures 11 to 13B The examples and embodiments described in the DU (e.g., service DU, first DU, or second DU) can be applied to Figure 14A and Figure 14B DU in the middle. (Targeting) Figure 14A and Figure 14B The examples and embodiments described can be applied to the preceding figures.

[0280] Figure 15 This shows that it can be generated by DU (e.g., Figure 4 , Figures 6A to 6B and Figures 8A to 8B Example method 1500 implemented in S-DU for enabling LTM for UE (e.g., UE 102).

[0281] Method 1500 begins with the DU communicating with the UE using a first serving DU configuration 1502 (e.g., event 402, 602, or 802). The DU receives from the CU 1504 a first CU-DU message including a first LTM DU configuration for configuring a first cell for the UE using LTM (e.g., event 412, 493, 693, or 893). The DU generates a second serving DU configuration 1506 based on the first LTM DU configuration and optionally based on a TCI state configuration. The DU sends to the CU 1508 a first DU-CU message including the second serving DU configuration and a TCI state configuration (e.g., event 414, 493, 693, or 893). The DU communicates with the UE 1510 according to the second serving DU configuration (e.g., event 424, 436, 444, 498, 624, 698, 636, 824, 898, or 836). The DU sends a 1512 request for the UE to connect to the first LTM command of the first cell (e.g., events 430, 450, 498, 630, 698, 830, or 898).

[0282] In some embodiments, a DU is a serving DU. In some embodiments, a CU receives a first LTM DU configuration (e.g., 490, 690, or 890) from a target DU.

[0283] In some embodiments, the second service DU configuration enhances the first service DU configuration. For example, the second service DU configuration includes a (new) configuration that is not present in the first service DU configuration. In other embodiments, the second service DU configuration includes a (new) configuration that updates the (existing) configuration included in the first service DU configuration. Examples of the first and second service DU configurations are similar to those described above.

[0284] In some embodiments, a first LTM DU configuration includes at least one first RS resource configuration and at least one first reporting configuration for reporting measurements of some RSs configured in the first RS source configuration. In some embodiments, the DU generates at least one second RS resource configuration based on the first RS resource configuration and includes the second RS resource configuration in a second service DU configuration. In some embodiments, the DU generates at least one second reporting configuration for reporting measurement results of some RSs configured in the second RS resource configuration and includes the second reporting configuration in the second service DU configuration. In other embodiments, the DU generates at least one second reporting configuration for reporting measurement results of some RSs configured in the first RS resource configuration and includes both the first RS resource configuration and the second reporting configuration in the second service DU configuration. In some embodiments, a first service DU configuration includes at least one third RS resource configuration and / or at least one third reporting configuration for reporting measurement results of some RSs configured in the third RS resource configuration. In some embodiments, the RSs configured in the third RS resource configuration are different from the RSs configured in the first RS resource configuration and the second RS resource configuration. In some embodiments, some of the third reporting configurations are the same as the second reporting configurations. In other embodiments, the third reporting configuration is different from the second reporting configuration.

[0285] In some embodiments, the first LTM DU configuration includes at least one first TCI state configuration. In some embodiments, the DU generates at least one second TCI state configuration based on the first TCI state configuration and includes the second TCI state configuration in the second service DU configuration. In other embodiments, the DU includes the first TCI state configuration in the second service DU configuration. In some embodiments, the first service DU configuration includes at least one third TCI state configuration.

[0286] In some embodiments, the CU generates an RRC message including a second service DU configuration and sends the RRC message to the UE via a DU, an additional DU, or a BS. In some embodiments, the CU receives an RRC response message from the UE via a DU, an additional DU, or a BS. For example, the RRC message and the RRC response message are respectively associated with, for example, a second service DU configuration. Figures 3 to 8B The described RRC reconfiguration message is similar to the RRC reconfiguration completion message.

[0287] In some embodiments, the DU receives a second CU-DU message (e.g., events 490, 480, 680, 690, 681, 880, 890, or 881) from the CU, including a second LTM DU configuration for the UE. The DU generates a third service DU configuration based on the second LTM DU configuration. In some embodiments, the DU generates the third service DU configuration based on the second LTM DU configuration and a first service DU configuration. The DU sends a second DU-CU message (e.g., events 490, 480, 680, 690, 681, 880, 890, or 881) to the CU, including the third service DU configuration. The DU communicates with the UE according to the third service DU configuration (e.g., events 424, 436, 444, 498, 480, 624, 698, 680, 681, 636, 880, 881, 824, 898, or 836). In some embodiments, the third service DU configuration enhances the second service DU configuration. For example, the third service DU configuration includes a (new) configuration that does not exist in the second service DU configuration. In other embodiments, the third service DU configuration includes a (new) configuration that updates the (existing) configuration included in the second service DU configuration. Examples of third service DU configurations are similar to those described above.

[0288] In some embodiments, the second LTM DU configuration includes at least one fourth RS resource configuration and at least one fourth reporting configuration for reporting measurements of some RSs configured in the fourth RS source configuration. In some embodiments, the DU generates at least one fifth RS resource configuration based on the fourth RS resource configuration and includes the fifth RS resource configuration in the third service DU configuration. In some embodiments, the DU generates at least one fifth reporting configuration for reporting measurement results of some RSs configured in the fifth RS resource configuration and includes the fifth reporting configuration in the third service DU configuration. In other embodiments, the DU generates at least one fifth reporting configuration for reporting measurement results of some RSs configured in the fourth RS resource configuration and includes both the fourth RS resource configuration and the fifth reporting configuration in the third service DU configuration. In some embodiments, the RSs configured in the third RS resource configuration are different from the RSs configured in the fourth and fifth RS resource configurations. In some embodiments, some of the third reporting configurations are the same as the fifth reporting configurations. In other embodiments, the third reporting configuration is different from the fifth reporting configuration.

[0289] In some embodiments, the second LTM DU configuration includes at least one fourth TCI state configuration. In some embodiments, the DU generates at least one fifth TCI state configuration based on the fourth TCI state configuration and includes the fifth TCI state configuration in the third service DU configuration. In other embodiments, the DU includes the fourth TCI state configuration in the third service DU configuration.

[0290] In some embodiments, the (first or second) CU to DU message and the (first or second) DU to CU message are respectively UE Context Establishment Request Messages and UE Context Establishment Response Messages. In other embodiments, the (first or second) CU to DU message and the (first or second) DU to CU message are respectively UE Context Modification Request Messages and UE context modification response Message. In some alternative embodiments, the (first or second) DU to CU message is UE context modification requirements information.

[0291] Figure 16 This shows that it can be generated by DU (e.g., Figures 3 to 8B Example method 1600 for enabling LTM for a UE (e.g., UE 102) implemented in DU 174, 174A, 174B or 174C.

[0292] Method 1600 begins with the DU receiving, 1602, a first CU-DU message from the CU including a first LTM DU configuration for the UE, wherein the first LTM DU configuration is for LTM configuration of a first cell (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). The DU generates, 1604, a second DU configuration based on the first LTM DU configuration, wherein the second DU configuration is for LTM configuration of a second cell. The DU sends, 1606, a first DU-CU message to the CU including the second LTM DU configuration (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). The DU detects 1608 to indicate that the UE has successfully accessed the second cell. The DU sends 1610 to the CU to indicate that the UE has successfully accessed the second cell (e.g., events 332, 336, 352, 356, 380, 432, 436, 452, 456, 498, 480, 532, 536, 552, 598, 556, 580, 581, 582, 632, 636, 698, 656, 680, 681, 732, 736, 798, 756, 780, 832, 836, 898, 868, 880, or 881). The DU uses a second LTM configuration to communicate with the UE via a second cell 1612 (e.g., events 336, 356, 380, 436, 456, 480, 536, 556, 580, 581, 582, 636, 656, 680, 681, 736, 756, 780, 836, 856, 880, or 881).

[0293] In some embodiments, DU is a service DU, which can be such as Figure 4 , Figures 6A to 6B and Figures 8A to 8B The source DU or auxiliary DU as described. In other embodiments, the DU is as follows: Figure 4 , Figures 6A to 6B and Figures 8A to 8B The target DU as described.

[0294] In some embodiments, the DU generates a portion of a second LTM DU configuration based on a first LTM DU configuration, and generates the remainder of the second LTM DU configuration independently of the first LTM DU configuration. In some embodiments, the first LTM DU configuration includes at least one first RS resource configuration.

[0295] In some embodiments, a first LTM DU configuration includes at least one first RS resource configuration and at least one first reporting configuration for reporting measurement results of some RSs configured in the first RS resource configuration. In some embodiments, the DU generates at least one second RS resource configuration based on the first RS resource configuration and includes the second RS resource configuration in a second LTM DU configuration. In some embodiments, the DU generates at least one second reporting configuration for reporting measurement results of some RSs configured in the second RS resource configuration and includes the second reporting configuration in the second LTM DU configuration. In other embodiments, the DU generates at least one second reporting configuration for reporting measurement results of some RSs configured in the first RS resource configuration and includes both the first RS resource configuration and the second reporting configuration in the second LTM DU configuration. In some embodiments, the DU generates at least one third RS resource configuration and / or at least one third reporting configuration for reporting measurement results of some RSs configured in the third RS resource configuration. In some embodiments, the RSs configured in the third RS resource configuration are different from the RSs configured in the first RS resource configuration and the second RS resource configuration. In some embodiments, some of the third reporting configurations are the same as the second reporting configurations. In other embodiments, the third reporting configuration is different from the second reporting configuration.

[0296] In some embodiments, the first LTM DU configuration includes at least one first TCI state configuration. In some embodiments, the DU generates at least one second TCI state configuration based on the first TCI state configuration and includes the second TCI state configuration in the second LTM DU configuration. In other embodiments, the DU includes the first TCI state configuration in the second LTM DU configuration.

[0297] In some embodiments, the CU generates an RRC message including a second LTM DU configuration and sends the RRC message to the UE via a DU, an additional DU, or a BS. In some embodiments, in response, the CU receives an RRC response message from the UE via a DU, an additional DU, or a BS. For example, the RRC message and the RRC response message are respectively associated with, for example,... Figures 3 to 8B The described RRC reconfiguration message is similar to the RRC reconfiguration completion message.

[0298] In some embodiments, the DU receives a second CU-DU message from the CU including a third LTM DU configuration for the UE, wherein the third LTM DU configuration is for an LTM configuration of a third cell (e.g., events 490, 480, 680, 690, 681, 880, 890, or 881). The DU generates a fourth LTM DU configuration based on the third LTM DU configuration to update the second LTM DU configuration. The fourth LTM DU configuration is still for an LTM configuration of a second cell. In some embodiments, the DU generates a fourth DU configuration based on the third LTM DU configuration, the second LTM DU configuration, and the first LTM DU configuration. The DU sends a second DU-CU message to the CU including the fourth LTM DU configuration (e.g., events 490, 480, 680, 690, 681, 880, 890, or 881). In some embodiments, the fourth LTM DU configuration enhances the second LTM DU configuration. For example, the fourth DU configuration includes a (new) configuration that is not present in the second LTM DU configuration. In other embodiments, the fourth DU configuration includes a (new) configuration that updates the (existing) configuration included in the second LTM DU configuration.

[0299] In some embodiments, the third LTM DU configuration includes at least one fourth TCI state configuration. In some embodiments, the DU generates at least one fifth TCI state configuration based on the fourth TCI state configuration and includes the fifth TCI state configuration in the fourth LTM DU configuration. In other embodiments, the DU includes the fourth TCI state configuration in the fourth LTM DU configuration.

[0300] In some embodiments, the (first or second) CU to DU message and the (first or second) DU to CU message are respectively UE Context Establishment Request Messages and UE Context Establishment Response Messages. In other embodiments, the (first or second) CU to DU message and the (first or second) DU to CU message are respectively UE Context Modification Request Messages and UE context modification response Message. In some alternative embodiments, the (first or second) DU to CU message is UE context modification requirements information.

[0301] Figure 17An example method 1700 for enabling LTM for a UE (e.g., UE 102) is shown, which can be implemented by a CU (e.g., CU 172 of the first BS 104 or the second BS 106).

[0302] Method 1700 begins with the CU communicating with the UE via a serving DU 1702 (e.g., event 402, 602, or 802). The CU sends a first CU-DU message to the serving DU 1704, including a first LTM DU configuration for the UE (e.g., event 490, 690, or 890). The CU receives a first DU-CU message from the serving DU 1706, including a service DU configuration (e.g., event 490, 690, or 890). The CU sends the service DU configuration to the UE 1708 via the serving DU or a RAN node (e.g., events 494, 694, 617, 619, 894, 817, 819). In some embodiments, the RAN node is another DU (e.g., Figure 6A , Figure 6B , Figure 8A and Figure 8B M-DU or S-DU) or BS (e.g., MN or SN) in the context of BS.

[0303] In some embodiments, services DU and CU are respectively Figure 15 DU and CU. (Targeting) Figure 15 The examples and embodiments described are applicable to Figure 17 .

[0304] Figure 18 An example method 1800 for enabling LTM for a UE (e.g., UE 102) is shown, which can be implemented by a CU (e.g., CU 172 of the first BS 104 or the second BS 106).

[0305] Method 1800 begins with the CU communicating with the UE via a first DU 1802 (e.g., events 302, 402, 502, 602, 702, 802, 380, 480, 580, 680, 780, 880, 581, 582, 681, or 881). The CU sends a first CU-DU message to a second DU 1804, including a first LTM DU configuration for the UE (e.g., events 308, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881). The CU receives a first DU to CU message (e.g., events 310, 390, 380, 490, 480, 580, 590, 581, 582, 680, 690, 681, 780, 790, 880, 890, or 881) from the second DU at 1806. The CU then sends the second LTM DU configuration (e.g., events 316, 318, 394, 380, 494, 480, 580, 594, 581, 582, 680, 694, 617, 619, 780, 794, 880, 881, 894, 817, or 819) to the UE via the first DU or the RAN node at 1808. In some embodiments, the RAN node is another DU (e.g., Figure 6A , Figure 6B , Figure 8A and Figure 8B M-DU or S-DU) or BS (e.g., MN or SN) in the context of BS.

[0306] In some embodiments, the first DU is a service DU (e.g., Figure 3 DU 174 in Figure 4 S-DU in Figures 5A to 8B In the case of M-DU or S-DU), and the second DU is the target DU (e.g., Figure 4 , Figure 6A , Figure 6B , Figure 8A and Figure 8B In other embodiments, the second DU and the first DU are the same DU (i.e., the service DU, such as T-DU). Figure 3 DU 174 in Figure 4 S-DU in, or Figures 5A to 8B In some embodiments, the CU and the second DU are respectively M-DU or S-DU. Figure 16 CU and DU in the text. (This refers to...) Figure 16 The examples and embodiments described are applicable to Figure 18 In some embodiments, the service DU is Figure 15 The described service DU. (Targeting...) Figure 15The examples and embodiments described are applicable to Figure 17 .

[0307] A description of one of the above figures may be applied to another of the above figures. The examples, embodiments, and methods described above may be combined if there is no conflict. The events or boxes described above may be optional or omitted. For example, events or boxes with dashed lines in the figures may be optional. In some embodiments, "message" is used and may be replaced by "information element (IE)" or vice versa. In some embodiments, "IE" is used and may be replaced by "field" or vice versa. In some embodiments, "configurations" or "configuration parameters" may be used instead of "configuration" or vice versa. In some embodiments, "serving cell change command," "layer 1 / layer 2 handover command," "lower layer handover command," or "lower layer serving cell change command" may be used instead of "LTM command." In some embodiments, "some" means "one or more." In some embodiments, "at least one" means "one or more." In some embodiments, "cell group configuration" may be used instead of "DU configuration." In some embodiments, "serving cell index," "LTM cell index," "special cell (SpCell) index," "PCell index," or "PSCell index" may be used instead of "cell index." In some embodiments, "source" may be used instead of "service". In some embodiments, "measurement result" may be used instead of "measurement report".

[0308] The user device in which the technologies of this disclosure are implemented (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.

[0309] The numerical adjectives “first,” “second,” and “third” do not imply any order (they are not ordinal numbers), but are markers used to distinguish different instances of similar elements. Unless otherwise explicitly indicated, references to the singular (e.g., “a” or “a kind,” “the / the”) should include the plural.

[0310] As used herein, the phrase “at least one of” or “one or more of” in a list of items refers to any combination of those items, including a single member. For example, “at least one of the following: a, b, or c” is intended to cover the following possibilities: only a, only b, only c, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a, b, and c.

[0311] Although features and elements of the present embodiments are described in specific combinations in the examples, each feature or element may be used alone without other features and elements in the embodiments, or in various combinations with or without other features and elements disclosed herein. Methods or flowcharts may be implemented as computer programs, software, or firmware tangibly embodied in a computer-readable storage medium for execution by a specially programmed computer or processor.

[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 (e.g., as encompassed within a general-purpose processor or other programmable processor) that are temporarily configured by software to perform certain operations. 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] Upon reading this disclosure, those skilled in the art will understand the additional and alternative structural and functional designs used to address mobility between BSs through the principles disclosed herein. Therefore, while specific embodiments and applications have been shown and described above, it should be understood that the disclosed embodiments are not limited to the precise constructions and components disclosed herein. Various modifications, alterations, and variations that will be apparent to those skilled in the art may be made to the arrangement, operation, and details of the methods and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims.

Claims

1. A wireless communication method performed by a distributed unit DU (174) of a base station BS (104), the method comprising: Receive (1204) request from the centralized unit CU (172) of the BS (104) for preparing a first cell (124C) for the user equipment (UE) (102) to hand over from the serving cell (124A) to the first cell (124C) for mobility LTM triggered by a lower layer. Generate (1206) an LTM DU configuration for communication with the first cell (124C); Generate (1208) a first Transmission Configuration Indicator (TCI) state configuration, the first TCI state configuration specifying at least one TCI state for the communication with the first cell (124C); and Send (1210) the LTM DU configuration and the first TCI status configuration to the CU (172).

2. The method of claim 1, further comprising: Send an LTM command to the UE, instructing the UE to access the first cell based on the first TCI state configuration.

3. The method of claim 1 or 2, further comprising: The UE has been detected to have switched to the first cell; as well as Send a notification signal to the CU that the UE has connected to the first cell.

4. The method of any one of claims 1 to 3, wherein the request includes a second TCI state configuration, and the generation of the first TCI state configuration is performed based on the second TCI state configuration.

5. The method according to any one of claims 1 to 4, further comprising: The service DU configuration is generated based on the LTM DU configuration and the first TCI state configuration; as well as Send the service DU configuration to the CU.

6. The method of claim 5, wherein the service DU configuration is for the serving cell or for the first cell.

7. The method of any one of claims 1 to 6, wherein sending the LTM DU configuration and the first TCI status configuration to the CU comprises: Send a first DU to CU message including the LTM DU configuration to the CU; as well as Send a second DU to CU message including the first TCI state configuration to the CU.

8. The method of claim 7, wherein: The first DU to CU message includes a first UE context establishment response message or a first UE context modification response message; and The second DU to CU message includes a second UE context establishment response message or a second UE context modification response message.

9. The method of any one of claims 1 to 6, wherein sending the LTM DU configuration and the first TCI status configuration to the CU comprises: The LTM DU configuration and the first TCI status configuration are sent to the CU in a single DU to CU message.

10. The method of claim 9, wherein the single DU to CU message includes a UE context establishment response message or a UE context modification response message.

11. A wireless communication method performed by a centralized unit CU (172) of a base station BS (104), the method comprising: The first distributed unit DU (174) of the BS (104) receives (904) a first lower layer triggered mobility LTM DU configuration for communication between the user equipment UE (102) and a first cell (124C), the first cell (124C) being different from the serving cell (124A); Receive (910) a first transmission configuration indicator (TCI) state configuration from the first DU (174), the first TCI state configuration specifying at least one TCI state for the UE to communicate with the first cell (124C); as well as Send (918) the LTM DU configuration and the first TCI state configuration to the UE (102).

12. The method of claim 11, further comprising: Send (1204) request to the first DU to prepare a CU-DU message for the first cell (124C) for LTM; as well as Receive (1210) a DU to CU message including the first LTM DU configuration and the first TCI status configuration.

13. The method of any one of claims 11 or 12, further comprising: The first TCI status configuration is sent to the second DU, wherein the first cell is associated with the first DU.

14. The method of claim 13, wherein the BS is a first BS, and the second DU is a target DU of the first BS or the second BS.

15. The method of any one of claims 11 to 14, further comprising: Send a second TCI status configuration to the first DU, wherein the first TCI status configuration is generated based on the second TCI status configuration.

16. The method of any one of claims 11 to 15, further comprising: Receive service DU configuration generated based on the LTM DU configuration from the service DU; as well as The service DU configuration is sent to the UE, wherein the service DU configuration is for the serving cell or for the first cell.

17. A wireless communication method performed by a distributed unit DU (174) of a base station BS (104), the method comprising: The CU (172) of the BS (104) receives (1302) a CU to DU message including a Transmission Configuration Indicator (TCI) state configuration, the TCI state configuration including at least one TCI state for communication between the User Equipment (UE) (102) and a first cell (124C) for a lower layer triggered Mobility LTM, the first cell (124C) being different from the serving cell (124A). as well as Send (1307) to the UE (102) an LTM command instructing the UE (102) to switch from the serving cell (124A) to the first cell (124C) based on the at least one TCI state, the LTM command including the identifier ID of the at least one TCI state.

18. The method of claim 15, wherein the CU to DU message includes a UE context establishment request message or a UE context modification request message.

19. A communication device (170, 172, 174), comprising: A transceiver (282), a processor (283), and a computer-readable storage medium (284) storing executable instructions for the processor to use the transceiver to perform any one of the methods described in claims 1 to 18.

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