Enabling inter-central-unit low-layer triggered mobility with dual connectivity

Abstract

Methods and apparatuses for managing inter-central unit low layer triggered mobility (LTM) are described herein. One method can be implemented in a master node (MN) that communicates with a source secondary node (S-SN) in dual connectivity (DC) with a user equipment (UE), and can include sending a request to a candidate secondary node (C-SN) for a candidate cell associated with the C-SN to prepare for low layer triggered mobility (LTM). The method can include receiving a message from the C-SN and in response to the request that includes an LTM configuration for the candidate cell. The method can include providing the LTM configuration to the UE. Other methods and apparatuses are described.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Provisional U.S. Patent Application No. 63 / 563,289, filed March 8, 2024, entitled "Enabling Inter-Central Unit Lower Layer Triggered mobility in Dual Connectivity". The entire contents of the provisional application are hereby expressly incorporated by reference. Technical Field

[0003] This disclosure relates to wireless communications, and more specifically, to enabling low-level triggered mobility (LTM) between central units (CUs) with dual connectivity (DC). Background Technology

[0004] 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.

[0005] Generally, base stations operating a cellular radio access network (RAN) use a radio access technology (RAT) and multiple layers of a radio protocol stack to communicate with user equipment (UE). For example, the physical layer (PHY) of the RAT provides a transport channel to the media access control (MAC) sublayer, which in turn provides a logical channel to the radio link control (RLC) sublayer, and the RLC sublayer in turn provides data delivery services to the packet data convergence protocol (PDCP) sublayer.

[0006] The PDCP sublayer of the radio protocol stack provides services such as user plane data delivery, encryption, and integrity protection. For example, the PDCP sublayer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP specification TS 36.323) and New Radio (NR) (see 3GPP specification TS 38.323) provides the ordering of Protocol Data Units (PDUs) in the uplink direction (from the user equipment, also known as the user equipment (UE), to the base station) and in the downlink direction (from the base station to the UE). Additionally, the PDCP sublayer provides Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs) to the Radio Resource Control (RRC) sublayer. Generally, the UE and base station can use SRBs to exchange RRC messages and Non-Access Stratum (NAS) messages, and the UE and base station can use DRBs to transmit data on the user plane.

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

[0008] When a UE moves from one cell's coverage area to another within the RAN, the RAN performs a serving cell change by configuring the UE to send Layer 3 (L3) measurement results. Based on the L3 measurement results received from the UE, the RAN sends an RRC reconfiguration message with synchronization (e.g., the RRC reconfiguration message includes...). ReconfigurationWithSyncIE) is used for changes in the serving cell (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 the PCell or PSCell. Serving cell changes involve a full L2 (and L1) reset, resulting in longer latency, greater overhead, and longer outage times. To address these issues, 3GPP recently proposed a process called Low Layer Triggered Mobility (LTM).

[0009] During RAN communication between the base station and the UE via the serving cell associated with the base station, the base station receives one or more Layer 3 (e.g., RRC) measurement results from the UE. Based on the Layer 3 (L3) measurement results, the base station determines an LTM candidate cell for LTM cell handover configuration. To configure the LTM candidate cell for the UE, the base station sends the LTM candidate configuration to the UE via RRC signaling. Subsequently, the base station receives one or more Layer 1 (L1) measurement results from the UE. Based on the one or more L1 measurement results, the base station determines that the LTM candidate cell is eligible to become the UE's serving cell. After this determination, the base station sends an LTM cell handover command to the UE to instruct the UE to perform an LTM cell handover to the LTM candidate cell. The UE responds to the LTM cell handover command by performing a cell change from the serving cell to the LTM candidate cell. The base station includes a central cell (CU) and one or more distributed cells (DUs). One of the DUs operating the serving cell is called the serving DU. If the LTM candidate cell is operated by the serving DU, the LTM cell handover is an intra-CU, intra-DU LTM cell handover. If an LTM candidate cell is operated by a candidate DU (C-DU) within a DU, then the LTM cell handover is an LTM cell handover between DUs within a CU. 3GPP has enabled both intra-CU and inter-CU LTM cell handovers in Release 18 of the specification. However, it is unclear how the device should handle inter-CU LTM cell handovers. For example, it is unclear how the device should handle situations where an LTM candidate cell is operated within candidate DUs of different CUs. Furthermore, it is unclear how to handle inter-CU LTM cell handovers in a DC scenario. Summary of the Invention

[0010] An example embodiment of these technologies is a method implemented in a primary node (MN) that communicates with a source secondary node (S-SN) under dual connectivity (DC) with a user equipment (UE). The method includes: sending a request to a candidate secondary node (C-SN) for candidate cells associated with the C-SN to prepare for low-layer triggered mobility (LTM); receiving from the C-SN and in response to the request a message including LTM configuration for the candidate cells; and providing the LTM configuration to the UE.

[0011] Another example embodiment of these technologies is a method implemented in a candidate secondary node (C-SN). The method includes: receiving from a primary node (MN) a request for candidate cells associated with the C-SN for preparation of low-layer triggered mobility (LTM), the MN communicating with a source secondary node (S-SN) under dual connectivity (DC) with a user equipment (UE); and sending to the MN and in response to the request a message including LTM configuration for the candidate cells.

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

[0013] Figure 1A This is a block diagram of an example system in which the radio access network (RAN) and user equipment (UE) can implement the techniques of this disclosure for enabling LTM handover between CUs in a DC-enabled manner;

[0014] Figure 1B This is another block diagram of an example system in which the RAN and UE can implement the techniques disclosed herein for enabling LTM handover between CUs via DC;

[0015] Figure 1C It is possible Figure 1A or Figure 1B A block diagram of an example base station operating in the system, including a central unit (CU) and a distributed unit (DU);

[0016] Figure 2A This is a block diagram of an example protocol stack. Figure 1A The UE communicates with the base station according to the protocol stack;

[0017] Figure 2B This is a block diagram of an example protocol stack. Figure 1A The UE communicates with the CU and DU according to the protocol stack;

[0018] Figure 3 This is a message sequence diagram of an example LTM scenario within a DU;

[0019] Figure 4 This is a message sequence diagram of an example DU-LTM scenario;

[0020] Figure 5 This is a message sequence diagram of an example CU-to-CU LTM scenario;

[0021] Figure 6A This is a message sequence diagram of an example CU-to-CU LTM scenario, where the UE is in the DC with the MN and SN;

[0022] Figure 6B This is the message sequence diagram for the second example CU-to-CU LTM scenario, where the UE is in the DC with the MN and SN;

[0023] Figure 6C This is the message sequence diagram for the third example CU-to-CU LTM scenario, where the UE is in the DC with the MN and SN;

[0024] Figure 6D This is the message sequence diagram for the fourth example CU-to-CU LTM scenario, where the UE is in the DC with the MN and SN;

[0025] Figure 7A This is a flowchart of a first example method for supporting LTM in a dual-connectivity (DC) scenario, which can be implemented in the source-secondary node (S-SN).

[0026] Figure 7B This is a flowchart of a second example method for supporting LTM in a DC scenario, which can be implemented in S-SN;

[0027] Figure 7C This is a flowchart of a third example method for supporting LTM in DC scenarios, which can be implemented in S-SN;

[0028] Figure 8A This is a flowchart of a first example method for supporting LTM in a DC scenario, which can be implemented in the source central unit (S-CU);

[0029] Figure 8B This is a flowchart of a second example method for supporting LTM in a DC scenario, which can be implemented in an S-CU;

[0030] Figure 8C is a flowchart of a third example method for supporting LTM in a DC scenario that can be implemented in the S-CU;

[0031] Figure 9A This is a flowchart of a first example method for supporting LTM in a DC scenario, which can be implemented in the master node (MN);

[0032] Figure 9B This is a flowchart of a second example method for supporting LTM in a DC scenario, which can be implemented in MN;

[0033] Figure 10A This is a flowchart of a first example method for supporting LTM in a DC scenario, which can be implemented in the CU of MN (MN-CU);

[0034] Figure 10B This is a flowchart of a second example method for supporting LTM in a DC scenario, which can be implemented in the CU of MN-CU;

[0035] Figure 11 This is a flowchart of an example method for supporting LTM in a DC scenario that can be implemented in a candidate SN (C-SN);

[0036] Figure 12 This is a flowchart of a first example method for supporting LTM in a DC scenario, which can be implemented in the CU (C-CU) of the candidate node;

[0037] Figure 13 This is a flowchart of a second example method for supporting LTM in a DC scenario, which can be implemented in C-CU;

[0038] Figure 14 This is a flowchart of a first example method for supporting LTM in a DC scenario, which can be implemented in the source SN (S-SN);

[0039] Figure 15 This is a flowchart of a second example method for supporting LTM in a DC scenario, which can be implemented in S-SN;

[0040] Figure 16 This is a flowchart of the first example method for supporting LTM in a DC scenario, which can be implemented in MN;

[0041] Figure 17 This is a flowchart of a second example method for supporting LTM in a DC scenario, which can be implemented in MN;

[0042] Figure 18 This is a flowchart of an example method that can be implemented in SN to support LTM in DC scenarios;

[0043] Figure 19 This is a flowchart of an example method for LTM between CUs under DC, which can be implemented in MN; and

[0044] Figure 20 This is a flowchart of an example method for LTM between CUs under DC, which can be implemented in SN. Detailed Implementation

[0045] The techniques disclosed herein can be used to perform LTM cell handover within a CU of a base station or between multiple DUs of a base station. Various aspects of this disclosure also provide techniques for performing LTM cell handover when a UE is in DC mode, and methods for canceling or releasing candidate cells based on measurement reports or other criteria.

[0046] First refer to Figure 1AThat is, an example wireless communication system 100 that can implement one or more of these technologies. The wireless communication system 100 includes a UE 102, a base station (BS) 104A, a base station 106A, and a core network (CN) 110. Base stations 104A and 106A operate in a radio access network (RAN) 105. UE 102 is initially connected to base station 104A. In some scenarios, base station 104A can perform SN addition to configure UE 102 to operate with both base stations 104A and 106A in dual connectivity (DC). Base stations 104A and 106A operate as the MN and SN of UE 102, respectively.

[0047] In various configurations of the wireless communication system 100, base station 104A can operate as a primary eNB (MeNB) or primary gNB (MgNB), and base station 106A can operate as a secondary gNB (SgNB). UE 102 can communicate with base station 104A and base station 106A via the same RAT (such as EUTRA or NR) or different RATs. When base station 104A is a MeNB and base station 106A is an SgNB, UE 102 can be in EUTRA-NR DC (EN-DC) with both the MeNB and SgNB.

[0048] In some cases, the MeNB or SeNB is implemented as an ng-eNB instead of an eNB. When base station 104A is the primary ng-eNB (Mng-eNB) and base station 106A is the SgNB, UE 102 can be in a next-generation (NG) EUTRA-NR DC (NGEN-DC) with both the Mng-eNB and SgNB. When base station 104A is a MgNB and base station 106A is an SgNB, UE 102 can be in an NR-NR DC (NR-DC) with both the MgNB and SgNB. When base station 104A is a MgNB and base station 106A is a secondary ng-eNB (Sng-eNB), UE 102 can be in an NR-EUTRA DC (NE-DC) with both the MgNB and Sng-eNB.

[0049] In the scenario where UE 102 is handed over from base station 104A to base station 106A, base stations 104A and 106A operate as the source base station (S-BS) and the destination base station (T-BS), respectively. For example, before the handover, UE 102 can communicate with base station 104A and the additional base station (T-BS). Figure 1A (Not shown in the diagram) operates in DC mode. After the handover is completed, UE 102 can continue to operate in DC mode with base station 106A and the additional base station, or UE 102 can operate in single-connection (SC) mode with base station 106A. In the latter case, base stations 104A and 106A operate as the source MN (S-MN) and the target MN (T-MN), respectively.

[0050] The core network (CN) 110 can be either the Evolved Packet Core (EPC) 111 or the 5th Generation Core (5GC) 160; both are... Figure 1A The description is as follows, but CN 110 can support other cores. Base station 104A can be an eNB supporting the S1 interface for communication with EPC 111, an ng-eNB supporting the NG interface for communication with 5GC 160, or a gNB supporting the NR radio interface and the NG interface for communication with 5GC 160. To exchange messages directly with each other during the scenarios discussed below, base stations 104A and 106A can support X2 or Xn interfaces.

[0051] like Figure 1A As shown, base station 104A supports cell 124A, and base station 106A supports cell 126A. Cells 124A and 126A can partially overlap, allowing UE 102 to communicate with base stations 104A and 106A via DC, where one of base stations 104A and 106A is MN and the other is SN. Base station 104A can support additional cells (such as cell 124B), and base station 106A can support additional cells (such as cell 124B). Figure 1A (Not shown in the diagram). Cells 124A and 124B may partially overlap, allowing UE 102 to communicate with base station 104A via carrier aggregation (CA). Base station 104A may operate cells 124A and 124B via one or more transmit and receive points (TRPs). More specifically, when UE 102 is in a DC configuration with base stations 104A and 106A, one of base stations 104A and 106A operates as a MeNB, Mng-eNB, or MgNB, while the other operates as an SgNB or Sng-eNB.

[0052] Generally, RAN 105 can include any suitable number of base stations supporting NR cells and / or EUTRA cells. More specifically, EPC 111 or 5GC 160 can connect to any suitable number of base stations supporting NR cells and / or EUTRA cells. See below for reference. Figure 1B An example configuration of CN 110 connected to an additional base station is discussed. Although the examples below specifically refer to particular CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general, the techniques disclosed herein can also be applied to other suitable radio access and / or core network technologies, such as sixth-generation (6G) radio access and / or 6G core networks or 5G NR-6G DC.

[0053] Continue to refer to Figure 1ABase station 104A includes processing hardware 130, which may include one or more general-purpose processors (e.g., CPUs) and a non-transitory computer-readable storage medium 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 from one or more user equipments (e.g., UE 102) on a physical downlink (DL) channel and a DL reference signal via one or more cells (e.g., cells 124A and / or 124B) and / or one or more TRPs. PHY controller 132 is also configured to receive data and control signals from one or more user equipments on a physical uplink (UL) channel and / or a UL reference signal via one or more cells (e.g., cells 124A, 124B) and / or one or more TRPs. In an example implementation, processing hardware 130 includes 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 advance (TA) for one or more user equipment (UEs), and / or communicating UL / DLMAC PDUs with one or more UEs. MAC functions include low-layer triggered mobility (LTM, also referred to herein as L1 / L21 triggered mobility or low-layer triggered mobility) related functions as described below. In the example, LTM functions are coordinated with MAC controller 134 via LTM controller 137 or receive control via signaling to the MAC controller. Processing hardware 130 may also include RRC controller 136 to implement procedures and messaging at the RRC sublayer of the protocol communication stack. For example, RRC controller 136 may be configured to support RRC messaging associated with handover procedures and / or support necessary operations when base station 104A operates as an MN relative to an SN or an SN relative to an MN. When base station 104A is a distributed base station, CU LTM controller 137A may operate in the CU, and DU LTM controller 137B may operate in the DU (see [link to CU]). Figure 1C Base station 106A may include processing hardware 140 similar to processing hardware 130. In particular, components 142, 144, 146 and 147 may be similar to components 132, 134 and 136 and 137, respectively.

[0054] UE 102 includes 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 from base station 104A or 106A on a physical DL channel and / or DL ​​reference signal via one or more cells (e.g., cells 124A, 124B, and / or 126A) and / or one or more TRPs. PHY controller 152 is also configured to transmit data and control signals to base station 104A or 106A on a physical UL channel and / or UL reference signal via one or more cells (e.g., cells 124A, 124B, and / or 126A) and / or one or more TRPs. In an example implementation, processing hardware 150 includes a MAC controller 154 configured to perform MAC functions with base station 104A or 106A. 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 base station 104A or 106A. In another example, MAC functions include LTM-related functions as described below. 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.

[0055] In operation, UE 102, located in DC, can use radio bearers (e.g., DRB or SRB) that terminate at different times on MN 104A or SN 106A. When communicating on radio bearers in the uplink (UL) (from UE 102 to the base station) and / or downlink (from the base station to UE 102) directions, UE 102 can apply one or more security keys. The UE can use several types of SRBs and DRBs. When operating in DC, a primary cell group (MCG) is defined with the base station operating in MN, and a secondary cell group (SCG) is defined with the base station operating in SN. For example, a first type of SRB resource, referred to as SRB1 resource, carries RRC messages, which in some cases include NAS messages on the dedicated control channel (DCCH). A second type of SRB resource, referred to as SRB2 resource, supports RRC messages, which include recorded measurement information or NAS messages, also on the DCCH but with a lower priority than SRB1 resources. More generally, SRB1 and SRB2 resources allow the UE and MN to exchange MN-related RRC messages as well as embedding SN-related RRC messages. SRB1 and SRB2 can be referred to as MCG SRBs. SRB3 resources allow the UE and SN to exchange SN-related RRC messages and can be referred to as SCG SRBs. Split SRBs allow the UE to exchange RRC messages directly with the MN via the lower-level resources of the MN and SN. In addition, a DRB that uses only the lower-level resources of the MN can be referred to as an MCG DRB, a DRB that uses only the lower-level resources of the SN can be referred to as an SCG DRB, and a DRB that uses both MCG and SCG lower-level resources can be referred to as a split DRB.

[0056] Figure 1B This is another block diagram of example system 100B, in which the radio access network (RAN) and user equipment can implement the techniques disclosed herein for managing processes associated with the MN or SN (e.g., LTM processes and inter-CU LTM processes). Figure 1B and Figure 1A similar. Figure 1B CN 110 is depicted, having additional base stations 104A, 104B, 106A, and 106B connected thereto and communicating in cells 124A, 124B, 126A, and 126B. Base station 104A can also operate an additional overlapping cell 125.

[0057] Figure 1C Depicting Figure 1A or Figure 1BExamples of distributed or decomposed implementations of any one or more of the illustrated base stations (e.g., base stations 104A, 104B, 106A, or 106B). In this implementation, the base station includes a central unit (CU) 172 and one or more distributed units (DUs) 174. CU 172 includes processing hardware, such as one or more general-purpose processors (e.g., 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 includes processing hardware 130. In another example, CU 172 includes processing hardware 140 (… Figure 1A In the example implementation, processing hardware 140 includes an SN RRC controller, which can be coupled to RRC controller 146. Figure 1A Similarly, it is configured to manage or control one or more RRC configurations and / or RRC procedures when the base station 106A operates as an SN.

[0058] Each of the DU 174A includes processing hardware, which may include one or more general-purpose processors (e.g., 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 some examples, the processing hardware includes: a media access control (MAC) controller (e.g., MAC controllers 134, 144). Figure 1A The MAC controller is configured to manage or control one or more MAC operations or procedures (e.g., random access procedures); and the Radio Link Control (RLC) controller is configured to manage or control one or more RLC operations or procedures when the base station 106A 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.

[0059] In some implementations, CU 172 may include a logical node CU-CP172A that hosts the control plane of CU 172. CU 172 may also include a logical node CU-UP 172B that hosts the user plane of CU 172. CU-CP 172A may send control information (e.g., RRC messages, F1 application protocol messages), and CU-UP 172B may send data packets (e.g., SDAP PDUs or Internet Protocol packets).

[0060] CU-CP 172A can connect to multiple CU-UP 172Bs via the E1 interface. CU-CP 172A selects the appropriate CU-UP 172B for the service requested by UE 102. In some implementations, a single CU-UP 172B can connect to multiple CU-CP 172A via the E1 interface. CU-CP 172A can connect to one or more DU 174s via the F1-C or W1-C interface. CU-UP 172Bs can connect to one or more DU 174s via the F1-U or W1-U interface under the control of the same CU-CP 172A. In some implementations, a DU 174 can connect to multiple CU-UP 172Bs under the control of the same CU-CP 172A. In such implementations, the connectivity between CU-UP 172Bs and DU 174s is established by CU-CP 172A using bearer context management functions.

[0061] Figure 2A An example protocol stack 200 is shown in a simplified manner, which UE 102 can use to communicate with eNB / ng-eNB 230 or gNB 232 (e.g., one or more of base stations 104A and 106A).

[0062] 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 implementations, UE 102 supports both EUTRA and NR stacks, such as... Figure 2A As shown, this is to support the handover between EUTRA and NR base stations and / or support DCs via the 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.

[0063] EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 (e.g., from an Internet Protocol (IP) layer layered directly or indirectly on PDCP layers 208 or 210) receive packets that can be referred to as Service Data Units (SDUs), and (e.g., to RLC layers 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".

[0064] On the control plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 can provide signaling radio bearer (SRB) or RRC sublayer ( Figure 2A (Not shown) to exchange, for example, RRC messages or Non-Access Stratum (NAS) messages. On the user plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 can provide data radio bearers (DRBs) to support data exchange. The data exchanged on NR PDCP sublayer 210 can be SDAP PDUs, Internet Protocol (IP) packets, or Ethernet packets.

[0065] Figure 2B An example protocol stack 250 on which UE 102 can communicate with DU (e.g., DU 174) and CU (e.g., CU 172) is shown in a simplified manner. The radio protocol stack 200 is functionally split, as by... Figure 2B The radio protocol stack 250 is shown in the diagram. At either base station 104A or 106A, the CU can retain all control and upper-layer functionality (e.g., RRC 214, SDAP 212, NR PDCP 210), while lower-layer operations (e.g., NR RLC 206B, NR MAC 204B, and NR PHY 202B) are delegated to the DU. To support connectivity to the 5GC, NR PDCP 210 provides SRBs to RRC 214, and NR PDCP 210 provides DRBs to SDAP 212 and SRBs to RRC 214.

[0066] Next, refer to Figures 3 to 5 It is one of them Figure 1A Several example scenarios illustrate how a base station operating in a system sends a configuration to UE 102 and later activates the configuration for communication between UE 102 and the base station. Generally speaking, Figures 3 to 5 Similar events in the diagram are labeled with similar reference numerals that share two least significant figures, where the differences are discussed below where appropriate. For example, event 302 and... Figure 4 Event 402 and Figure 5Similar to event 502, and event 390 is similar to... Figure 4 Event 490 and Figure 5 Event 590 is similar. Apart from the differences shown in the figures and discussed below, any of the other implementations discussed for a particular event (e.g., for messaging and processing) can be applied to events labeled with similar reference numerals in other figures.

[0067] First refer to Figure 3 In scenario 300, base station 104A includes CU 172 and DU 174, and DU 174 operates in cell 124A. UE 102 is initially configured to communicate with DU 174 on the serving cell (e.g., cell 124A) using the serving DU 302, and the UE is configured to communicate with CU 172 via DU 174 using the serving CU 174 302. DU 174 is the serving or source DU (S-DU) of UE 102. In other words, DU 174 is the serving DU (S-DU) that communicates with UE 102. In some implementations, UE 102 uses the serving DU to configure communication with CU 172 on cell 124A and other cells (…). Figure 1A UE 102 communicates with DU 174 via carrier aggregation (CA) on cell 124A (not shown). DU 174 operates other cells. Cell 124A and / or other cells are the serving cells of UE 102. In other implementations, UE 102 communicates with DU 174 only on cell 124A (e.g., not on other cells). In some implementations, UE 102 communicates with DU 174 via one or more TRPs on cell 124A and / or other cells (i.e., the serving cells). In the following description, events 394, 324, 350, 352, 354, and 326 occur on the serving cell. In some implementations, 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 implementations, cell 124A may be an SCell, and one of the other cells is a PCell. In such cases, additional cells include SCells and / or additional cells associated with a PCell or SCell. In the following description, base station 104A may include DU 174, CU 172, or both DU 174 and CU 172.

[0068] In event 302, UE 102 may transmit UL PDUs and / or UL control signals to base station 104A via one or more TRPs in cell 124A and / or other cells. In some implementations, UE 102 communicates UL PDUs and / or DL ​​PDUs with base station 104A via a radio bearer, which may include SRBs and / or DRBs. Base station 104A may configure the radio bearer for UE 102. In some implementations, UL control signals include UL control information, channel state information, Hybrid Automatic Repeat Request (HARQ) acknowledgment (ACK), HARQ negation ACK, scheduling request, and / or probe reference signals. Similarly, UE 102 may receive DL PDUs and / or DL ​​control signals from base station 104A via one or more TRPs in cell 124A and / or other cells. In some implementations, 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). Base station 104A can transmit DCI via one or more TRPs on the physical downlink control channel (PDCCH) monitored by UE 102 on cell 124A and / or on other cells.

[0069] In some implementations, the serving DU configuration includes physical layer configuration parameters, MAC configuration parameters, and / or RLC configuration parameters. In some implementations, the serving DU configuration includes at least one first non-LTM Transport Configuration Indicator (TCI) state configuration for the serving cell. In some implementations, DU 174 may send these configuration parameters and / or the first non-LTM TCI state configuration to CU 172. CU 172 generates one or more messages (e.g., RRC reconfiguration messages) including the configuration parameters and / or the first non-LTM TCI state configuration. CU 172 sends these one or more messages to UE 102 via DU 174. In other implementations, DU 174 sends the configuration parameters and / or the first non-LTM TCI state configuration directly to UE 102. In some implementations, the serving DU configuration is as defined in 3GPP specification 38.331. CellGroupConfig IE. In other implementations, the service DU configuration includes... CellGroupConfig Configuration parameters in IE. In some implementations, the Serving CU configuration includes PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters. In some implementations, the Serving CU configuration includes those defined in 3GPP specification 38.331. MeasConfig IE and / or RadioBearerConfig IE, or the CU service configuration includes MeasConfig IE and / or RadioBearerConfigConfiguration parameters in IE. Radio configuration parameters or RadioBearerConfig IE configures one or more DRBs. In some implementations, the service DU configuration includes... CSI- MeasConfig IE or configuration parameters used for Channel State Information (CSI) measurement and reporting. In other implementations, the service CU configuration includes... CSI-MeasConfig IE or configuration parameters used for CSI measurement and reporting. In some implementations, UE 102 receives the service CU configuration or configuration parameters in the service CU configuration from CU 172 via DU 174. In other implementations, UE 102 receives a portion of the service CU configuration and / or a portion of the service DU configuration from a base station other than base station 104A, and the UE receives the remainder of these configuration parameters from base station 104A.

[0070] In some implementations, DU 174 and UE 102 communicate with each other using a first non-LTM TCI state configuration, for example, in events 302, 318, 320, 324, 350, 354, and / or 326. In some implementations, DU 174 sends at least one first non-LTM TCI state activation / deactivation command (e.g., MAC control element (CE)) to UE 102 to activate the first non-LTM TCI state configuration. UE 102 activates the first non-LTM TCI state configuration in response to the first non-LTM TCI state activation / deactivation command. In some implementations, DU 174 includes a serving cell ID (e.g., a serving cell index) in each of the first non-LTM TCI state activation / deactivation commands to identify the first non-LTM TCI state configuration. Each serving cell ID indicates a corresponding serving cell among serving cells. In some implementations, the serving DU configuration includes the serving cell ID and configures the association between the serving cell ID and the first non-LTM TCI state configuration.

[0071] When communicating with base station 104A, UE 102 sends at least one measurement report (304) to DU 174. In some implementations, the measurement report includes measurement results for the serving cell (e.g., cell 124A) and / or at least one non-serving cell of UE 102. For each of the measurement reports, DU 174 sends a DU-to-CU message (306) including the measurement report to CU 172. In some implementations, the DU-to-CU message is an F1 Application Protocol (F1AP) message (e.g., UL RRC Messaging (Message). At least one serving cell includes cell 124A and / or other cells, and at least one non-serving cell includes cell 124B and / or Figure 1AAdditional cells are not shown. In some implementations, the serving CU configuration includes at least one measurement configuration. Based on the measurement configuration, UE 102 performs measurements and sends a 304 measurement report to DU 174. In some implementations, the measurement configuration includes a Layer 3 (L3) measurement configuration (e.g., MeasConfig (IE), and the measurement report includes the L3 measurement report.

[0072] Upon receiving one or more measurement reports from UE 102 (e.g., in response to receiving one or more measurement reports from UE 102), CU 172 determines a first cell (e.g., cell 1, such as cell 124B) for UE 102 as an LTM candidate cell. In some implementations, base station 104A determines the first cell for UE 102 because the measurement reports indicate that the first cell can be used by base station 104A to communicate with UE 102. In some implementations, base station 104A determines the first cell for UE 102 because the measurement reports indicate that the first cell is eligible to be an LTM candidate cell that can be used for communication with UE 102. In some implementations, CU 172 determines the first cell for UE 102 if the L3 measurement reports indicate that the signal strength and / or quality of the first cell is higher than a first predetermined threshold, better than the signal strength and / or quality of the serving cell (e.g., cell 124A), and / or better than the signal strength and / or quality of the serving cell by a first predetermined threshold. Alternatively, regardless of whether a measurement report is received from UE 102, CU 172 determines to prepare the first cell for UE 102.

[0073] In response to determining that a first cell is ready for LTM, CU 172 sends a 385 First CU to DU message to DU 174 to prepare the first cell for UE 102. In some implementations, CU 172 includes the cell identifier (ID) 1 of the first cell in the First CU to DU message to request DU 174 to prepare the first cell for LTM for UE 102. In one example, cell ID1 includes 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 some implementations, CU 172 includes an LTM indicator in the First CU to DU message to indicate that DU 174 will prepare the first cell for LTM. In some implementations, CU 172 includes the LTM indicator in... LTM Information Establishment In IE, and will LTM Information Establishment The IE is included in the first CU to DU message. In other implementations, CU 172 includes the LTM indicator. LTM Information Modification In IE, and will LTM Information ModificationThe IE is included in the first CU to DU message.

[0074] In response to the first CU to DU message, DU 174 generates a first LTMDU configuration (hereinafter referred to as LTM DU configuration 1) for UE 102, configuring the first cell for LTM. In some implementations, CU 172 includes the first LTM configuration ID (hereinafter referred to as LTM ID 1) in the first CU to DU message, and DU 174 associates LTM ID 1 and / or cell ID 1 with LTM DU configuration 1. Then, DU 174 sends a first DU to CU message 310 including LTM DU configuration 1 to CU 172 in response to the first CU to DU message.

[0075] Events 385 and 310 in Figure 3 This process is collectively referred to as the LTM preparation process 390.

[0076] In some implementations, DU 174 includes the cell ID 1 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. When CU 172 and DU 174 perform multiple LTM preparation procedures (e.g., procedures 390 and LTM preparation procedures 2, ..., N described below) to prepare multiple LTM candidate cells, CU 172 can determine whether LTM DU configuration 1 is configured for or associated with the first cell based on the cell ID 1 in the first DU to CU message.

[0077] In some implementations, CU 172 does not include the LTM reference DU configuration in the first CU-DU message. In such cases, DU 174 generates the LTM reference DU configuration and includes it in the first DU-CU message. In some implementations, DU 174 generates LTM DU configuration 1 as an incremental configuration to expand the LTM reference DU configuration. In other implementations, DU 174 generates LTM DU configuration 1 as a complete configuration, i.e., not merely to expand the LTM reference DU configuration.

[0078] In some implementations, CU 172 includes an LTM reference DU configuration request in a first CU-DU message, and DU 174 generates an LTM reference DU configuration in response to the request and includes the LTM reference DU configuration in a first DU-CU message. In some implementations, CU 172 determines whether UE 102 supports an LTM reference configuration. In the context of this embodiment and as described in 3GPP specification 38.331, a reference configuration is a configuration provided by the network to the UE that is common to a set of configured incomplete candidate configurations within the same cell group. Candidate configurations may include complete candidate configurations or incremental configurations relative to the reference configuration. If CU 172 determines that UE 102 supports an LTM reference configuration, CU 172 includes an LTM reference DU configuration request in a first CU-DU message. DU 174 includes the LTM reference DU configuration in a first DU-CU message in response to the LTM reference DU configuration request. Otherwise, if CU 172 determines that UE 102 does not support the LTM reference configuration, CU 172 does not include the LTM reference DU configuration request in the first CU-DU message. In this case, DU 174 can generate LTM DU configuration 1 as a complete configuration and may not include the LTM reference DU configuration in the first DU-CU message. In other implementations, instead of sending the LTM reference DU configuration request in the first CU-DU message, CU 172 sends an additional CU-DU message to DU 174 including the LTM reference DU configuration request. In response, DU 174 sends an additional DU-CU message to CU 172 including the LTM reference DU configuration. In yet another implementation, DU 174 determines whether UE 102 supports the LTM reference configuration. If DU 174 determines that UE 102 supports the LTM reference configuration, DU 174 includes the LTM reference DU configuration in the first DU-CU message. Otherwise, if DU 174 determines that UE 102 does not support the LTM reference configuration, then DU 174 will not include the LTM reference DU configuration in the first DU to CU message.

[0079] In some implementations, CU 172 includes the LTM reference DU configuration in the first CU-DU message. In some implementations, CU 172 receives the LTM reference DU configuration from the additional DU during the LTM preparation process, as described above and referenced. Figure 4As described. In other implementations, CU 172 is pre-configured with an LTM reference DU configuration. In some implementations, DU 174 generates LTM DU configuration 1 as an incremental configuration to expand the LTM reference DU configuration. In other implementations, DU 174 ignores the LTM reference DU configuration and generates LTM DU configuration 1 as a complete configuration, i.e., not merely to expand the LTM reference DU configuration.

[0080] If DU 174 generates LTM DU configuration 1 as a complete configuration, DU 174 can include a complete configuration indication in the first DU to CU message to indicate that LTM DU configuration 1 is a complete configuration. In some implementations, if the first CU to DU message does not include the LTM reference DU configuration, then CU 172 can determine that LTM DU configuration 1 is a complete configuration. Otherwise, if the first CU to DU message includes the LTM reference DU configuration, then CU 172 can determine that LTM DU configuration 1 is an incremental configuration.

[0081] In some implementations, the LTM reference DU configuration differs from the service DU configuration. In some implementations, a portion of the LTM reference DU configuration is identical to a portion of the service DU configuration, and the remainder of the LTM reference DU configuration differs from the rest of the service DU configuration. In still other implementations, the LTM reference DU configuration is identical to the service DU configuration. In some implementations, the LTM reference DU configuration includes physical layer configuration parameters, MAC configuration parameters, and / or RLC configuration parameters. In some implementations, the LTM reference DU configuration is as defined in 3GPP specification 38.331. CellGroupConfig IE. In other implementations, the LTM reference DU configuration includes... CellGroupConfig Configuration parameters in IE. In some implementations, the LTM reference DU configuration includes... CSI-MeasConfig IE or configuration parameters used for Channel State Information (CSI) measurement and / or reporting.

[0082] In some implementations, the LTM reference DU configuration differs from the service DU configuration. In some implementations, a portion of the LTM reference DU configuration is identical to a portion of the service DU configuration, and the remainder of the LTM reference DU configuration differs from the rest of the service DU configuration. In other implementations, the LTM reference DU configuration is identical to the service DU configuration.

[0083] To prepare a first cell for UE 102 as an LTM candidate cell, CU 172 may send a second CU-DU message 312 to DU 174, including CSI resource configuration (e.g., CSI resource configuration 1) and / or LTM SSB configuration (i.e., LTM SSB configuration 1), to request DU 174 to generate one or more CSI report configurations (e.g., (LTM) CSI report configuration 1). The CSI resource configuration (e.g., (LTM) CSI resource configuration 1) includes configuration parameters for at least one reference signal (RS) transmitted on the first cell. The RS includes an SSB and / or a CSI-RS. The LTM SSB configuration includes SSB configuration parameters for the SSB transmitted on the first cell, including SSB frequency, subcarrier spacing, SSB periodicity, SSB location, and / or SSB power.

[0084] Upon receiving the CSI resource configuration (e.g., in response to receiving the CSI resource configuration), DU 174 generates one or more CSI report configurations based on the CSI resource configuration and includes the CSI report configuration in the service DU configuration (referred to as the second service DU configuration to distinguish it from the service DU configuration in event 302). In some implementations, the CSI report configuration configures UE 102 to send CSI reports based on RS measurements. DU 174 sends a second DU to CU message 314, which includes the second service DU configuration, to CU 172. In some implementations, the CSI resource configuration includes (e.g., is or includes) one or more... LTM-CSI-ResourceConfig-r18 IE. In other implementations, CSI resource configuration includes... ltm-CSI- ResourceConfigToAddModList Field / IE. In some implementations, the second service DU configuration is... CellGroupConfig IE.

[0085] In some implementations, CU 172 includes cell ID 1 and / or LTM ID 1 in the second CU-DU message (e.g., at event 312). In one implementation, CU 172 includes cell ID 1 and / or LTM ID 1 in the second CU-DU message to indicate that the CSI resource configuration is associated with the first cell. In another implementation, CU 172 therefore includes cell ID 1 and / or LTM ID 1 in the second CU-DU message so that DU 174 can associate LTM ID 1 with the first cell, cell ID 1, LTM DU configuration 1, and / or CSI reporting configuration. Based on the above implementations, DU 174 can associate LTM ID 1 and / or cell ID 1 with configurations associated with the first cell (e.g., LTM DU configuration 1, CSI resource configuration, and / or CSI reporting configuration). In such implementations, in some embodiments, CU 172 includes LTM ID 1 in the first CU-DU message. In other embodiments, CU 172 does not include the LTM ID configuration in the first CU to DU message.

[0086] In some alternative implementations, CU 172 includes CSI resource configuration in the first CU to DU message, and DU 174 includes CSI report configuration in the first DU to CU message.

[0087] In some implementations, DU 174 sends LTM SSB configuration or SSB configuration parameters to CU 172, for example, in a first DU to CU message, a second DU to CU message, or an additional DU to CU message. In some implementations, DU 174 sends an additional DU to CU message in response to receiving an additional CU to DU message from CU 172. In other implementations, DU 174 sends a fourth DU to CU message in response to receiving a first CU to DU message or a second CU to DU message (e.g., ...). UE context modification beg information).

[0088] Events 312 and 314 Figure 3 This is collectively referred to as the LTM CSI report configuration and / or LTM ID configuration process 392.

[0089] After receiving the first DU to CU message, CU 172 generates a first LTM candidate configuration (i.e., LTM candidate configuration 1) including LTM DU configuration 1, and generates a first RRC reconfiguration message including LTM candidate configuration 1 and LTM ID 1. In some implementations, CU 172 includes LTM CU configuration 1 in LTM candidate configuration 1. In other implementations, CU 172 does not include LTM CU configuration in LTM candidate configuration 1. CU 172 sends a third CU to DU 174, message 316, including the first RRC reconfiguration message. Subsequently, DU 174 sends a first RRC reconfiguration message 318 to UE 102. In response, UE 102 sends a first RRC reconfiguration completion message 320 to DU 174. DU 174 then sends a third DU to CU 172, message 322, including the first RRC reconfiguration completion message.

[0090] If the first DU to CU message includes an LTM reference DU configuration, then CU 172 generates an LTM reference configuration that includes the LTM reference DU configuration. In this case, CU 172 can include the LTM reference configuration in the first RRC reconfiguration message. In some implementations, CU 172 includes the LTM reference CU configuration in the LTM reference configuration. In this case, CU 172 can generate LTM CU configuration 1 as an incremental configuration based on the LTM reference CU configuration. In other implementations, CU 172 does not include the LTM reference CU configuration in the LTM reference configuration. In this case, CU 172 can generate LTM CU configuration 1 as a complete configuration. Alternatively, CU 172 sends a second RRC reconfiguration message including the LTM reference configuration to UE 102 via DU 174, similar to events 316 and 318. In response, UE 102 sends a second RRC reconfiguration complete message to CU 172 via DU 174, similar to events 320 and 322. In some implementations, if CU 172 does not receive the LTM reference DU configuration, CU 172 can generate an LTM reference configuration that includes only the LTM reference CU configuration. In other implementations, if CU 172 does not receive the LTM reference DU configuration, CU 172 may not generate an LTM reference configuration.

[0091] In some implementations, if the first DU to CU message includes a full configuration indication, then CU 172 can determine that LTM DU configuration 1 is a full configuration. Otherwise, if the first DU to CU message does not include a full configuration indication, then CU 172 can determine that LTM DU configuration 1 is an incremental configuration. In some implementations, if LTM DU configuration 1 is a full configuration, then CU 172 generates LTM candidate configuration 1 as a full configuration. Otherwise, if LTM DU configuration 1 is an incremental configuration, then CU 172 generates LTM candidate configuration 1 as an incremental configuration. If LTM candidate configuration 1 is a full configuration, then CU 172 includes a full configuration indication in the first RRC reconfiguration message to indicate that LTM candidate configuration 1 is a full configuration. If LTM candidate configuration 1 is an incremental configuration, then CU 172 excludes the full configuration indication from the first RRC reconfiguration message to indicate that LTM candidate configuration 1 is an incremental configuration.

[0092] When CU 172 performs procedure 392, CU 172 may include the second service DU configuration in the first RRC reconfiguration message. Alternatively, in events similar to 316 and 318, CU 172 sends a third RRC reconfiguration message including the second service DU configuration to UE 102 via DU 174. In response, in events similar to 320 and 322, UE 102 sends a third RRC reconfiguration completion message to CU 172 via DU 174.

[0093] In some implementations, CU 172 includes the CSI resource configuration in the first, second, or third RRC reconfiguration message. In other implementations, in events similar to 316 and 318, CU 172 sends a fourth RRC reconfiguration message including the CSI resource configuration to UE 102 via DU 174. In response, in events similar to 320 and 322, UE 102 sends a fourth RRC reconfiguration complete message to CU 172 via DU 174.

[0094] In some implementations, DU 174 sends a DU-to-CU message to CU 172, including early synchronization information for UE 102. The DU-to-CU message can be a first DU-to-CU message, a second DU-to-CU message, or a fourth DU-to-CU message. In some implementations, DU 174 sends a fourth DU-to-CU message in response to receiving a fourth CU-to-DU message from CU 172. In other implementations, DU 174 sends a fourth DU-to-CU message in response to receiving a first CU-to-DU message or a second CU-to-DU message (e.g., UE context modification requirementsIn one implementation, if DU 174 determines that UE 102 supports (i.e., is capable of) early UL synchronization with the LTM candidate cell (e.g., early TA acquisition with the LTM candidate cell, early RA on the LTM candidate cell, or TA measured by the UE), then DU 174 sends a fourth DU to CU message. Otherwise, if DU 174 determines that UE 102 does not support early UL synchronization with the LTM candidate cell, then DU 174 does not send early synchronization information to CU 172. In other implementations, CU 172 sends a CU to DU message that includes an early synchronization information request (e.g., IE), and DU 174 includes the early synchronization information in the DU to CU message in response to the early synchronization information request. The CU to DU message can be a first CU to DU message, a second CU to DU message, or a fourth CU to DU message. In one implementation, if CU 172 determines that UE 102 supports early UL synchronization with the LTM candidate cell, then CU 172 may send an early synchronization information request. Otherwise, if CU172 determines that UE 102 does not support early UL synchronization with the LTM candidate cell, CU 172 does not request DU 174 to provide early synchronization information for UE 102. If CU 172 receives early synchronization information, CU 172 includes the early synchronization information in a first RRC reconfiguration message, a second RRC reconfiguration message, a third RRC reconfiguration message, or a fourth RRC reconfiguration message. Alternatively, in events similar to events 316 and 318, CU 172 sends a fifth RRC reconfiguration message including early synchronization information to UE 102 via DU 174. In response, in events similar to events 320 and 322, UE 102 sends a fifth RRC reconfiguration complete message to CU 172 via DU 174.

[0095] In some implementations, the early synchronization information includes a Random Access Channel (RACH) configuration (i.e., RACH configuration 1) and / or one or more TCI state configurations (i.e., TCI state configuration 1). In some implementations, the early synchronization request may include a request for RACH configuration. If the early synchronization request includes a request for RACH configuration, then DU 174 includes the RACH configuration in the early synchronization information or in the DU-CU message (e.g., in the first DU-CU message, the second DU-CU message, or the fourth DU-CU message). Otherwise, if the early synchronization request does not include a request for RACH configuration, then DU 174 does not include the RACH configuration in the early synchronization information or in the DU-CU message.

[0096] In some implementations, CU 172 includes one or more other LTM-related configurations for the first cell in the first RRC reconfiguration message, the second RRC reconfiguration message, the third RRC reconfiguration message, the fourth RRC reconfiguration message, and / or the fifth RRC reconfiguration message. For example, other LTM-related configurations include the PCI of the first cell and / or the LTM SSB configuration.

[0097] Events 316, 318, 320, and 322 are in Figure 3 This is collectively referred to as LTM configuration delivery process 394. LTM configuration delivery process 394 may further include a second RRC reconfiguration message, a third RRC reconfiguration message, a fourth RRC reconfiguration message, and / or a fifth RRC reconfiguration message, as well as a second RRC reconfiguration completion message, a third RRC reconfiguration completion message, a fourth RRC reconfiguration completion message, and / or a fifth RRC reconfiguration completion message, related CU-to-DU messages, and / or related DU-to-CU messages. In some implementations, the RRC reconfiguration message and RRC reconfiguration completion message described above are respectively... RRCReconfiguration Messages and RRCReconfigurationComplete information.

[0098] In some implementations, the first CU to DU message is UE Context Modification Request Message, and the first DU to CU message UE context modification response Message. In some implementations, the second CU to DU message is UE Context Modification Request The message, and the second DU to CU message is UE context modification response or UE context modification requirements Message. In UE context modification Require In the case of a message, CU 172 can respond to UE context modification requirements Message sent to DU 174 UE context modification Change Confirmation Message. In some implementations, the third CU to DU message is DL RRC Message Passing Message. In other implementations, the third CU to DU message is UE Context Modification Request Message. In some implementations, the third DU to CU message is UL RRC message passing Message. In other implementations, the third DU to CU message is UE context modification response information.

[0099] In some implementations, the LTM reference CU configuration differs from the service CU configuration. In some implementations, a portion of the LTM reference CU configuration is identical to a portion of the service CU configuration, and the remainder of the LTM reference CU configuration differs from the remainder of the service CU configuration. In other implementations, the LTM reference CU configuration is identical to the service CU configuration.

[0100] In some implementations, the LTM reference CU configuration includes PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters. In some implementations, LTM CU configuration 1 includes those defined in 3GPP specification 38.331. MeasConfig IE and / or RadioBearerConfig IE, or LTM CU configuration 1 includes MeasConfig IE and / or RadioBearerConfig Configuration parameters in Internet Explorer.

[0101] In some implementations, LTM CU Configuration 1 and / or LTM Reference CU Configuration include PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters. In some implementations, LTM CU Configuration 1 or LTM Reference CU Configuration includes those defined in 3GPP specification 38.331. MeasConfig IE and / or RadioBearerConfig IE, or LTM CU configuration 1 or LTM reference CU configuration including MeasConfig IE and / or RadioBearerConfig Configuration parameters in Internet Explorer.

[0102] In some implementations, LTM DU configuration 1 includes multiple configuration parameters for UE 102 to communicate with DU 174 on the first cell. In some implementations, these multiple configuration parameters include physical layer configuration parameters (e.g., PhysicalCellGroupConfig IE), MAC layer configuration parameters (e.g., MAC-CellGroupConfig IE) and / or RLC configuration parameters (e.g., RLC-BearerConfig (IE). In some other implementations, 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 implementations, LTM DU configuration 1 is defined in 3GPP specification 38.331. CellGroupConfig IE. In other implementations, LTM DU configuration 1 includes... CellGroupConfig Configuration parameters in Internet Explorer.

[0103] In some implementations, LTM DU configuration 1 includes a first L1 measurement configuration (e.g., CSI-MeasConfigThe first L1 measurement configuration includes at least one first RS resource configuration and / or at least one first reporting configuration. In other implementations, LTM CU configuration 1 includes a first TCI status configuration. In some implementations, the first L1 measurement configuration includes at least one first RS resource configuration and / or at least one first reporting configuration. In some implementations, the first RS resource configuration configures one or more RSs or one or more RS resources associated with cell 1. RSs include SSBs and / or CSI-RSs. RS resources include SSB resources and / or CSI-RS resources. In some implementations, each of the first RS resource configurations includes an RS resource configuration ID. In some implementations, the first RS resource configuration is... CSI-ResourceConfig IE (and similar). In some implementations, the first report configuration configures one or more UL resources (e.g., PUCCH resources or PUSCH resources) for UE 102 on the first cell to transmit measurement results (e.g., CSI reports or LTM CSI reports). In some implementations, each of the first report configurations includes one or more RS resource configuration IDs that identify one or more RS resource configurations included in the first RS resource configuration. In some implementations, each of the first TCI state configurations associates one or two DL RSs with the TCI state associated with the corresponding quasi-co-located (QCL) type. The DL RS is associated with cell 1.

[0104] After receiving the LTM-related configuration and the second service DU configuration, or after receiving the RRC reconfiguration message described above, UE 102 measures at least one first RS, generates at least one first L1 measurement result based on the measurement, and sends at least 324 first L1 measurement reports including the first L1 measurement results to DU 174. The first RS may include an SSB and / or a CSI-RS. In some implementations, the first RS and / or the transmission mode of the first RS are configured in the CSI report configuration, LTM SSB configuration, and / or CSI resource configuration. UE 102 measures the first RS according to the CSI report configuration, LTM SSB configuration, and / or CSI resource configuration.

[0105] After receiving the LTM-related configuration and the second service DU configuration, or after receiving the RRC reconfiguration message described above, UE 102 measures at least one second RS, generates at least one second L1 measurement result based on the measurement, and sends at least one second L1 measurement report including the first L1 measurement result to DU 174. The second RS may include an SSB and / or a CSI-RS. In some implementations, the second RS and / or the transmission mode of the second RS are configured in the service DU configuration in event 302 and / or in one or more second CSI report configurations and / or one or more second CSI resource configurations included in the second service DU configuration. UE 102 measures the second RS according to the second CSI report configuration and / or the second CSI resource configuration. The second CSI report configuration may include a non-LTM CSI report configuration and / or an LTM CSI report configuration. The second CSI resource configuration may include a non-LTM CSI resource configuration and / or an LTM CSI resource configuration.

[0106] After sending the RACH configuration to UE 102 via CU 172, DU 174 can send a 350 PDCCH command to UE 102 to instruct UE 102 to send an RA preamble on the first cell. In response to the PDCCH command, UE 102 sends the RA preamble on the first cell. DU 174 includes PDCCH command information in the PDCCH command. The PDCCH command information includes an RA preamble index, a UL or supplementary UL indicator, an SSB index, and / or a physical RACH mask index. In some implementations, DU 174 includes LTMID 1 in the PDCCH command to indicate the first cell. UE 102 identifies the first cell based on LTM ID 1 in the PDCCH command and uses the PDCCH command information to send a 352 RA preamble to DU 174 on the first cell. Correspondingly, DU 174 receives the 352 RA preamble according to the PDCCH command information. In some implementations, DU 174 may determine the SSB index based on L1 measurement report 324, CSI resource configuration, CSI report configuration, and / or LTM SSB configuration. In some implementations, the L1 measurement report may include the SSB index. In other implementations, the L1 measurement report includes the SS / PBCH block resource indicator (SSBRI) corresponding to the SSB index. Therefore, DU 174 determines the SSB index based on the SSBRI.

[0107] In some implementations, DU 174 determines whether to send a PDCCH command based on the L1 measurement result 324. In some implementations, if the L1 measurement result indicates that the first cell is eligible for UE 102 to perform RA for early UL synchronization, DU 174 sends a PDCCH command. Otherwise, if the L1 measurement result indicates that the first cell is not eligible for UE 102 to perform RA for early UL synchronization, DU 174 avoids sending a PDCCH command. In other implementations, if the L1 measurement result indicates that the first cell is eligible for UE 102 access, DU 174 sends a PDCCH command. Otherwise, if the L1 measurement result indicates that the first cell is not eligible for UE 102 access, DU 174 avoids sending a PDCCH command. In yet another implementation, DU 174 sends a PDCCH command after receiving the RRC reconfiguration complete message 320, regardless of the L1 measurement result 324.

[0108] After sending a 324 L1 measurement report or a 352 RA preamble, UE 102 may send a 354 additional L1 measurement report to DU 174, similar to event 324. DU 174 determines, based on the additional L1 measurement report and / or based on L1 measurement report 324, a command for UE 102 to perform an LTM cell handover to a first cell. In response to this determination, DU 174 generates an LTM cell handover command (e.g., MAC CE) including LTM ID1 (e.g., a configuration identifier) ​​and sends a 326 LTM cell handover command to UE 102. In response to this determination, DU 174 may send a 328 DU-CU cell handover notification message to CU 172. In response to the LTM cell handover command, UE 102 performs an LTM cell handover to the first cell. During the LTM cell handover, UE 102 accesses the first cell (332) and sends a 336 RRC reconfiguration complete message to DU 174 via the first cell. DU 174 sends a DU-CU message (e.g., 338) to CU172, which includes an RRC reconfiguration completion message. UL RRC Messaging (Message). When UE 102 receives an LTM cell handover command, UE 102 identifies LTM candidate configuration 1 from LTM ID 1 and uses LTM candidate configuration 1 to access the first cell (332). Depending on the implementation, UE 102 may stop communicating on the serving cell in response to the LTM cell handover command. Subsequently, DU 174 sends a fifth DU-CU message to CU 172, including an RRC reconfiguration completion message. When DU 174 detects that UE 102 has accessed the first cell in event 332, DU 174 may send an access success message (334) to CU 172 to indicate that UE 102 has accessed the first cell.

[0109] In some implementations, DU 174 includes the TA value used for UL synchronization with the first cell in the LTM cell handover command. In one implementation, DU 174 derives the TA value based on the RA preamble (e.g., the timing of the RA preamble reception). In another implementation, DU 174 derives the TA value from the UL transmission from UE 102 on the serving cell (e.g., cell 124A). UE 102 applies the TA value in the UL transmission to synchronize with the first cell. After applying the TA value, UE 102 transmits the first UL transmission on the first cell based on LTM Candidate Configuration 1 without performing the RA procedure on the first cell. In some implementations, UE 102 transmits the first UL transmission on the first cell using UL authorization. In this case, the first UL transmission is a PUSCH transmission. In some implementations, the PUSCH transmission includes an RRC reconfiguration complete message 336. In some implementations, the UL authorization is configured authorization, and LTM Candidate Configuration 1 or LTM DU Configuration 1 includes a configured authorization configuration for configuring authorization. In other implementations, the UL grant is a dynamic grant received by UE 102 on the PDCCH of the first cell. After sending the first UL transmission, UE 102 receives the PDCCH transmission addressed to UE 102's C-RNTI and determines that the LTM cell handover was successfully completed in response to the receipt of the PDCCH transmission.

[0110] PDCCH transmissions may include UL grants or DL ​​assignments. If a PDCCH transmission includes a UL grant, UE 102 uses the UL grant to send a PUSCH transmission to DU 174 on the first cell. If a PDCCH transmission includes a DL assignment, DU 174 sends a PDSCH transmission to UE 102 on the first cell according to the DL assignment. DU 174 may send an Access Success Message 334 to CU 172 after receiving (e.g., in response to) a first UL transmission, sending a PDCCH transmission, receiving a PUSH transmission, or sending a PDSCH transmission.

[0111] In other implementations, DU 174 does not include the TA value in the LTM cell handover command. If the LTM cell handover command does not include the TA value, UE 102 performs a 332 RA procedure on the first cell according to the RA configuration parameters. In some implementations, the RA configuration parameters are included in LTM candidate configuration 1 or LTM DU configuration 1. In some implementations, the RA configuration parameters configure PRACH resources, the association between SSB and PRACH resources, and / or one or more PRACH timings. If UE 102 successfully completes the RA procedure, UE 102 determines that the LTM cell handover to the first cell has been successfully completed. Depending on the implementation and / or the RA configuration parameters, the RA procedure can be a four-step RA procedure or a two-step RA procedure. During a four-step RA procedure, UE 102 sends message 3 on the first cell, and in response, DU 174 sends message 4 to UE 102 on the first cell. During the two-step RA procedure, UE 102 sends message A on the first cell, and in response, DU 174 sends message B to UE 102 on the first cell. UE 102 may include the RRC reconfiguration complete message 336 in message 3 or message A. Alternatively, UE 102 sends the RRC reconfiguration complete message 336 after completing the RA procedure. After receiving message 3, message A, or the RRC reconfiguration complete message 336, or after sending message 4 or message B, DU 174 may send an access success message 334 to CU 172.

[0112] After successfully completing the LTM cell handover to the first cell as described above, UE 102 communicates with DU 174 and CU 172 via the first cell using LTM candidate configuration 1 340. In the case of the LTM reference configuration, UE 102 first applies the LTM reference configuration and then applies LTM candidate configuration 1 to extend the LTM reference configuration.

[0113] In some implementations, each of the TCI state configurations includes a TCI state ID. In some implementations, DU 174 includes the first TCI state ID, indicating the first in the TCI state configuration, in the LTM cell handover command. UE 102 identifies the first in the TCI state configuration based on the first TCI state ID and applies the first TCI state configuration in events 332, 336, and / or 340 to communicate UL and / or DL ​​transmissions with DU 174. In events 332, 336, and / or 340, DU 174 applies the first TCI state configuration to communicate UL and / or DL ​​transmissions with UE 102.

[0114] In some implementations, CU 172 may prepare additional cells (i.e., cells 2, ..., N) as LTM candidate cells for UE 102 before or after sending the LTM cell handover command, or during or after procedures 390 or 392, as described above. N is an integer greater than 1. For example, CU 172 and DU 174 perform additional LTM preparation procedures 2, ..., N to prepare cells 2, ..., N respectively. Each of LTM preparation procedures 2, ..., N is similar to procedure 390. In LTM preparation procedures 2, ..., N, CU 172 receives LTM DU configurations 2, ..., N respectively configured for LTM. CU 172 generates LTM candidate configurations 2, ..., N respectively, including LTM DU configurations 2, ..., N. CU 172 assigns LTM IDs 2, ..., N to identify LTM DU configurations 2, ..., N and LTM candidate configurations 2, ..., N respectively. CU 172 can obtain CSI resource configurations 2, ..., N, and perform CSI report configuration and / or LTM ID configuration procedures 2, ..., N with DU 174 to obtain CSI report configurations 2, ..., N, as described for CSI resource configuration 1 and CSI report configuration 1, respectively. CU 172 can obtain RACH configurations 2, ..., N for cells 2, ..., N, as described for RACH configuration 1, respectively. CU 172 can obtain TCI status configurations 2, ..., N for cells 2, ..., N, as described for TCI status configuration 1, respectively. Each of the CSI report configuration and / or LTM ID configuration procedures 2, ..., N is similar to procedure 392. CU 172 can obtain LTM SSB configurations 2, ..., N for cells 2, ..., N, as described for LTM SSB configuration 1, respectively. In some implementations, CU 172 may perform LTM configuration delivery procedures 2, ..., N with UE 102 to send to UE 102 lists including the following: {LTM ID 2, LTM candidate configuration 2, CSI resource configuration 2 (if obtained), TCI state configuration 2 (if obtained), RACH configuration 2 (if obtained), LTM SSB configuration 2 (if obtained)}, ..., {LTM ID N, LTM candidate configuration N, CSI resource configuration N, TCI state configuration N (if obtained), RACH configuration N (if obtained), LTM SSB configuration N (if obtained)}. Each of LTM configuration delivery procedures 2, ..., N is similar to procedure 394. In other implementations, CU 172 includes the list in the first RRC reconfiguration message.

[0115] In some implementations, after receiving the 334 to Access Success message or the 338 to DU to CU message, CU172 may send a 342 CU to DU message to DU 174. In one implementation, CU 172 sends the 342 CU to DU message to release the radio resources and / or configurations configured for UE 102 in the serving cell. In another implementation, CU 172 sends the 342 CU to DU message to release some of LTM candidate cells 2, ..., N. In this case, CU 172 releases any information or settings associated with the corresponding LTM candidate cell. In response to the CU to DU message 342, DU 174 sends a 344 DU to CU message 344 to CU 172. In some implementations, the CU to DU message 342 and the DU to CU message 344 are respectively... Please modify the UE context. beg Messages and UE context modification response information.

[0116] In some implementations, the LTM ID or configuration identifier is provided in different formats depending on which command or message provides the LTM ID. For example, the LTM ID may be provided differently in a PDCCH command, an LTM cell handover command, and an RRC reconfiguration message. For instance, a PDCCH command or LTM cell handover command may include a first field to include LTM ID 1, and a first RRC reconfiguration message may include a second field to include LTM ID 1. In some implementations, the first and second fields have different formats or encoding schemes. For example, the first field may use a binary format (i.e., 3 bits) with values ​​ranging from 0 to 7, and the second field may use an integer format with values ​​ranging from 1 to 8. In this example, a first field with a binary value of 000b is equivalent to a second field with an integer value of 1, a first field with a binary value of 001b is equivalent to a second field with an integer value of 2, and so on, and a first field with a binary value of 111b is equivalent to a second field with an integer value of 8.

[0117] Events 304, 306, 390, 392, 394, and 324 are in Figure 3 This is collectively referred to as the CU-DU-LTM configuration process 396. Events 304, 306, 390, 392, 394, 324, 350, 352, 354, 326, 328, 332, 334, 336, 338, and 340 are in... Figure 3 The process is collectively referred to as CU-internal DU-internal LTM process 380.

[0118] Next reference Figure 4In scenario 400, base station 104A includes CU 172, S-DU 174A, and candidate DU (C-DU) 174B. S-DU 174A operates cell 124A (… Figure 1A It can optionally operate additional cells, while the C-DU 174B operates different cells (e.g., cell 126). Scenario 400 is an intra-CU inter-DU scenario, similar to scenario 300. Therefore, the description for scenario 300 can be largely applied to scenario 400. Figure 3 Some descriptions of DU 174 in the document can be applied to Figure 4 S-DU 174A in, and for Figure 3 Some descriptions of DU 174 in the document can be applied to C-DU 174B. The differences between scenarios 300 and 400 are described below.

[0119] Initially, UE 102 uses the serving DU to configure communication with S-DU 174A on one or more serving cells (e.g., cell 124A and / or other cells) 402, and UE 102 uses the serving CU to configure communication with CU 172 via S-DU 174A. In some implementations, CU 172 and S-DU 174A may perform LTM configuration procedure 496 or LTM procedure 480 with UE 102, respectively, with reference to [reference missing]. Figure 3 The described processes 396 and 380 are similar. In the case of process 480, UE 102 can perform an LTM cell handover to the first cell (e.g., cell 124B), as described in the reference. Figure 3As described. After a successful LTM cell handover, the first cell becomes the serving cell, and cell 124A and / or other cells are no longer serving cells for UE 102. In the case of procedure 496, UE 102 does not perform an LTM cell handover. During communication 402, UE 102 sends at least one measurement report (e.g., an L3 measurement report) via S-DU 174A to CU 172 in steps 404 and 406. Based on the measurement report, CU 172 determines cell 1 (e.g., cell 126 operated by C-DU 174B) to be prepared for LTM for UE 102. Cell 1 is identified by cell ID (i.e., cell ID1). In response to the determination, CU 172 performs LTM preparation procedure 490 with C-DU 174B to prepare or request C-DU 174B to prepare cell 1 as an LTM candidate cell for UE 102. In LTM preparation process 490, CU 172 sends a first CU-DU message to C-DU 174B, including cell ID 1 of cell 1, to request C-DU 174B to prepare cell 1 as an LTM candidate cell for UE 102, similar to event 385. In response, C-DU 174B sends a first DU-CU message to CU 172, including the LTM DU configuration (e.g., LTM DU configuration 1), similar to event 310. In some implementations, CU 172 requests an LTM reference DU configuration in the first CU-DU message, such as a reference DU configuration. Figure 3 As described. In other implementations, CU 172 does not request the LTM reference DU configuration. In some implementations, C-DU 174B includes the LTM reference DU configuration in the first DU to CU message, as reference Figure 3 As described. In other implementations, the C-DU 174B does not include the LTM reference DU configuration in the first DU to CU message.

[0120] In some implementations, if CU 172 receives LTM reference DU configuration from S-DU 174A, such as reference... Figure 3 As described, CU 172 can include the LTM reference DU configuration in the first CU-DU message, and C-DU 174B can generate an incremental configuration of the LTM DU configuration based on the LTM reference DU configuration. In this case, C-DU 174B does not send the LTM reference DU configuration for UE 102 to CU 172. In other implementations, CU 172 receives the LTM reference DU configuration from C-DU 174B, for example, in the first DU-CU message or an additional DU-CU message, such as the reference DU configuration. Figure 3As described. In such cases, CU 172 can generate an LTM reference configuration that includes the LTM reference DU configuration. In some implementations, CU 172 includes the LTM reference CU configuration in the LTM reference configuration. In other implementations, CU 172 does not include the LTM reference CU configuration in the LTM reference configuration.

[0121] To prepare Cell 1 for LTM, CU 172 can perform a 492 LTM CSI report configuration and / or LTM ID configuration procedure with S-DU 174A. In procedure 492, CU 172 sends a second CU-DU message to S-DU 174A, including a CSI resource configuration (e.g., CSI resource configuration 1) and / or an LTM SSB configuration (i.e., LTM SSB configuration 1), similar to event 312. In response, S-DU 174A sends a second DU-CU message to CU 172, including one or more CSI report configurations (e.g., CSI report configuration 1). In some implementations, CU 172 generates an LTM candidate configuration (e.g., LTM candidate configuration 1) including an LTM DU configuration and assigns an LTM ID (e.g., LTM ID 1) to identify the LTM DU configuration and / or LTM candidate configuration, as referenced. Figure 3 As described. In some implementations, CU 172 includes {LTM ID 1, Cell ID 1} as a tuple in the second CU to DU message.

[0122] To prepare Cell 1 as an LTM candidate cell for UE 102, CU 172 can receive early synchronization information for Cell 1 from C-DU 174B in a DU-CU message (e.g., a first DU-CU message or an additional DU-CU message). In some implementations, C-DU 174B sends an additional DU-CU message in response to receiving an additional DU-CU message from CU 172. In other implementations, C-DU 174B sends an additional DU-CU message in response to receiving a first CU-DU message (e.g., ...). UE Context modification requirements Message). Early synchronization information includes RACH configuration (e.g., RACH configuration 1) and / or at least one TCI state configuration (e.g., TCI state configuration 1), as referenced. Figure 3 As described. In some implementations, the C-DU 174B includes the PDCCH command information (PDCCH command information 1) used for early UL synchronization with the first cell in the early synchronization information or in the DU to CU message.

[0123] In some implementations, CU 172 may receive LTM SSB configuration or SSB configuration parameters in the LTM SSB configuration from C-DU 174B, for example, in a first DU-CU message or an additional DU-CU message. In some implementations, CU 172 may receive the PCI of cell 1 from C-DU 174B, for example, in a first DU-CU message or an additional DU-CU message. In some implementations, C-DU 174B sends an additional DU-CU message in response to receiving an additional CU-CU message from CU 172. In other implementations, C-DU 174B sends an additional DU-CU message in response to receiving a first CU-CU message (e.g., ...). UE context modification requirements information).

[0124] For reference Figure 3 As described, CU 172 performs a 494 LTM configuration delivery procedure with UE 102 to send LTM ID 1 and LTM candidate configuration to UE 102. In some implementations, CU 172 sends {LTM ID, LTM candidate configuration} as a tuple in the first RRC reconfiguration message in procedure 494. Depending on the implementation, CU 172 may include the LTM reference configuration, CSI report configuration, CSI resource configuration, RACH configuration, TCI state configuration, LTM SSB configuration, and / or the PCI of cell 1 in the first RRC reconfiguration message to UE 102 and / or other RRC reconfiguration messages sent to UE 102, such as the reference configuration. Figure 3 As described. CU 172 includes the LTM ID in the first RRC reconfiguration message or other RRC reconfiguration messages to indicate that the CSI resource configuration, RACH configuration, TCI state configuration, LTM SSB configuration, and / or the PCI of cell 1 are associated with cell 1. For example, CU 172 includes the CSI resource configuration, RACH configuration, TCI state configuration, LTM SSB configuration, and / or the PCI of cell 1 in a tuple. In another example, CU 172 includes {LTM ID, CSI resource configuration, RACH configuration, TCI state configuration, LTM SSB configuration, and / or the PCI of cell 1} as a tuple in other RRC reconfiguration messages. In response to each of the other RRC reconfiguration messages, UE 102 sends an RRC reconfiguration complete message to CU 172 via S-DU 174A.

[0125] In some implementations, the PDCCH command information includes frequency domain resource assignment, RA preamble index, UL or supplementary UL indicator, SSB index, and / or physical RACH mask index. CU 172 can send a CU-DU message (e.g., a second CU-DU message or an additional CU-DU message) including the PDCCH command information to S-DU 174A. In some implementations, CU 172 includes LTM ID 1 or cell ID 1 in the CU-DU message to indicate that the PDCCH command information is associated with LTM ID 1 or cell ID 1. For example, when CU 172 sends the PDCCH command information in a second CU-DU message, CU 172 includes {cell ID 1, PDCCH command information} as a tuple in the CU-DU message. When CU 172 sends an additional CU-DU message, S-DU 174A can send an additional DU-CU message in response. The S-DU 174A sends a 450 PDCCH command to UE 102 based on the PDCCH command information. For example, the S-DU 174A sends a 450 PDCCH command including the PDCCH command information to UE 102. In some implementations, the S-DU 174A may determine the SSB index included in the PDCCH command based on L1 Measurement Report 424 and / or CSI Resource Configuration, CSI Report Configuration, and / or LTM SSB Configuration. In some implementations, the S-DU 174A includes LTM ID 1 in the PDCCH command to indicate cell 1. When CU 172 sends the PDCCH command information in an appended CU to DU message, the S-DU 174A may send an appended DU to CU message in response. UE 102 uses the RACH configuration and / or PDCCH command information to send a 452 RA preamble to C-DU 174B on cell 1. C-DU 174B derives the TA value based on the RA preamble. C-DU 174B sends DU-CU TA information transmission message 456, including the TA value, to CU 172. CU 172 then sends CU-DU TA information transmission message 458, including the TA value, to S-DU 174A. In some implementations, C-DU 174B includes cell ID 1, RA preamble index, RA radio network temporary identifier (RA-RNTI), and / or the DU ID of S-DU 174A in message 456. In such cases, CU 172 includes cell ID 1, RA preamble index, RA-RNTI, and / or the DU ID of S-DU 174A in message 458. In response to the determination command UE 102 to perform an LTM cell handover to cell 1, S-DU 174A sends an LTM cell handover command 456, including LTM ID 1, to UE 102.If the S-DU 174A receives a TA value, as described above, the S-DU 174A can include the TA value in the LTM cell handover command. The S-DU 174A can also include a first TCI status ID in the LTM cell handover command. The first TCI status ID indicates the first one in the TCI status configuration.

[0126] In some implementations, the C-DU 174B determines the RA-RNTI based on the PRACH timing of the RA preamble 452 received by the C-DU 174B. In some implementations, the C-DU 174B calculates the RA-RNTI as follows:

[0127]

[0128] Where s_id is the index of the first OFDM symbol of the PRACH timing (0≤s_id<14), t_id is the index of the first slot of the PRACH timing in the system frame (0≤t_id<80), where for μ={0,1,2,3}, the subcarrier spacing used to determine t_id is based on the value of μ specified in Clause 5.3.2 of 3GPP TS 38.211, and for μ={5,6}, t_id is the index of the 120 kHz slot in the system frame containing the PRACH timing (0≤t_id<80), f_id is the index of the PRACH timing in the frequency domain (0≤f_id<8), and ul_carrier_id is the UL carrier used for RA preamble transmission (0 is NUL carrier and 1 is SUL carrier).

[0129] In response to the confirmation command UE 102 to perform LTM cell handover or to send LTM cell handover command 426, S-DU174A sends command 428 to CU 172. DU-CU cell handover notification The message instructs UE 102 to perform an LTM cell handover to cell 1. In response, CU 172 sends a 430 message to C-DU 174B. CU-DU Cell Handover Notification The message instructs UE 102 to perform an LTM cell handover to cell 1. In some implementations, the S-DU 174A includes the first TCI state ID. DU-CU community switching Change notification The message, and CU 172 subsequently included the first TCI status ID. CU-DU Cell Handover Notification In the message, UE102 and C-DU 174B identify the first in the TC state configuration based on the first TCI state ID, and apply the first TCI state configuration in events 432, 436, and / or 440 to communicate UL and / or DL ​​transmissions. C-DU 174B sends an Access Success Message 434 to CU 172.

[0130] In some implementations, each of the TCI state configurations includes or is associated with a TCI state ID. In some implementations, CU 172 may send a CU-DU message (e.g., a second CU-DU message or an additional CU-DU message) to S-DU 174A that includes the TCI state configuration and / or the associated TCI state ID. In some implementations, CU 172 includes LTM ID 1 or Cell ID 1 in the CU-DU message to indicate that the TCI state configuration is associated with LTM ID 1 or Cell ID 1. For example, when CU 172 sends the TCI state configuration and / or the associated TCI state ID in a second CU-DU message, CU 172 includes {Cell ID 1, TCI state configuration} as a tuple in the CU-DU message. When CU 172 sends an additional CU-DU message, S-DU 174A may send an additional DU-CU message in response. In some implementations, the S-DU 174A includes the first TCI state ID, indicating the first in the TCI state configuration, in the LTM cell handover command 426. In some implementations, the S-DU 174A determines either the first TCI state configuration or the first TCI state ID. The UE 102 identifies one of the TCI state configurations based on the first TCI state ID and applies the first TCI state configuration to UL transmission and / or DL ​​reception in events 432, 436, and / or 440.

[0131] In some implementations, CU 172, together with C-DU 174B, can prepare additional cells (i.e., cells 2, ..., N) as LTM candidate cells for UE 102 before or after sending the LTM cell handover command, or during or after procedures 490 or 492, as shown in reference [reference missing]. Figure 3 As described.

[0132] In some implementations, 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 some implementations, the first CU to DU message and the first DU to CU message are... UE The following is a request for amendment. Messages and UE context modification response In some implementations, LTM preparation procedure 490 is a UE context establishment procedure, and the additional LTM preparation procedure is a UE context modification procedure. In other implementations, LTM procedure 490 and the additional LTM preparation procedure are both UE context establishment procedures. In yet another implementation, LTM procedure 490 and the additional LTM preparation procedure are both UE context modification procedures.

[0133] Events 404, 406, 490, 492, 494, and 424 are in Figure 4 This is collectively referred to as the CU-DU inter-LTM configuration process 496. Events 404, 406, 490, 492, 494, 424, 450, 452, 454, 456, 458, 426, 428, 430, 432, 434, 436, 438, 440, 442, and 444 are in... Figure 4 This is collectively referred to as the CU-internal DU-internal LTM process 480.

[0134] Next reference Figure 5 In scenario 500, base station 104A operates as a serving or source base station (S-BS), and base station 106A operates as a candidate base station (C-BS). C-BS 106A includes CU 172 and DU 174. Scenario 500 is similar to scenarios 300 and 400, except that scenario 500 is an inter-CU scenario (i.e., an inter-base station scenario), while scenarios 300 and 400 are intra-CU scenarios (i.e., intra-base station scenarios). S-BS 104A can include CU and DU (…). Figure 5 (not shown in the image), and Figure 3 and Figure 4 The base station 104A shown is similar. Initially, UE 102 communicates with S-BS 104A via the serving cell using the service configuration 502. In some implementations, S-BS 104A includes S-DU and CU, and the service configuration may include a serving CU configuration and a serving DU configuration, as shown in reference [reference missing]. Figure 3 and Figure 4 As described. During communication 502 with UE 102, S-BS 104A can perform an in-CU LTM procedure 580 with UE 102, similar to procedures 380 and / or 480. Alternatively, during communication 502 with UE 102, S-BS 104A can perform an in-CU LTM configuration procedure 596 with UE 102, similar to procedures 396 and / or 496.

[0135] When communicating with S-BS 104A, UE 102 sends at least one measurement report (504) to S-BS 104A. The measurement report includes measurement results for UE 102's serving cell and / or at least one non-serving cell (e.g., cell 126A). Based on the measurement report, S-BS 104A determines a first cell (e.g., cell 126A) to prepare for LTM candidate cell preparation for UE 102. For example, the measurement report includes the PCI of the first cell and the measurement results for cell 126A. S-BS 104A identifies the first cell as being operated by base station 106A based on the PCI and determines the first cell's eligibility for LTM preparation based on the measurement results.

[0136] After determining that a first cell is to be prepared as an LTM candidate cell for UE 102 (e.g., in response to determining that a first cell is to be prepared as an LTM candidate cell for UE 102), S-BS 104A (e.g., the CU of S-BS 104A) generates a first cell ID (i.e., cell ID 1) including the first cell (i.e., cell 1). Transfer Request Message. S-BS 104A sends 505 to CU 172. shift Submit a request Message. In some implementations, Transfer Request The message includes instructions Transfer Request The message contains an LTM indicator for the LTM of the first cell ID. Upon receiving... Transfer Request Following the message (e.g., in response to receiving a handover request message), CU172 and DU174 perform LTM preparation procedure 590 to prepare a first cell as an LTM candidate cell for UE102, similar to procedures 390 or 490. In procedure 590, CU172 sends a first CU-DU message including the first cell ID to DU174 to request preparation of the first cell, similar to event 385. In response, CU172 can receive a first DU-CU message including LTM DU configuration 1 from DU174, similar to event 310. CU172 generates a first LTM candidate configuration (LTM candidate configuration 1). In response to... transfer ask Message: CU 172 sends 507 to S-BS 104A, including the first LTM candidate configuration. Confirmation of transfer request Message. In some implementations, CU 172 includes the first cell ID. Confirmation of transfer request The message indicates that the first LTM candidate configuration is provided for or associated with the first cell (ID).

[0137] Events 505, 590, and 507 are in Figure 5 This is collectively referred to as the CU-inter-LTM preparation process (or, alternatively, the MN-inter-LTM preparation process) 598.

[0138] In some implementations, Transfer Request The message includes the DU ID of the S-DU of S-BS 104A. In such cases, CU 172 includes the DU ID in the first CU-to-DU message. In some implementations, Transfer Request The message includes the BS ID of S-BS104A. When the BS ID is received, CU 172 can include the BS ID in the first CU to DU message. For example, the BS ID could be the gNB ID.

[0139] In some implementations, CU 172 requests the LTM reference DU configuration in procedure 590, such as the reference... Figure 3 and Figure 4 As described. In other implementations, CU 172 does not request the LTM reference DU configuration in procedure 590. In some implementations, DU 174 sends the LTM reference DU configuration to CU 172 in procedure 590, as reference Figure 3 and Figure 4 As described. In other implementations, DU 174 does not send the LTM reference DU configuration to CU 172 in process 590. In some implementations, S-BS 104A (e.g., the CU of S-BS 104A) can obtain the LTM reference configuration, such as reference Figure 3 and Figure 4 As described. In other implementations, the S-BS 104A can be transferred from another BS during the LTM preparation process between another CU (as described). Figure 5 (Not shown in the image) Receives the LTM reference configuration, as described above and below in this document. If the S-BS 104A obtains the LTM reference configuration, the S-BS 104A can include the LTM reference configuration (the LTM reference configuration generated by the S-BS) in... Transfer Request In some implementations, the S-BS104A includes the LTM reference configuration in the inter-node RRC message. HandoverPreparationInformation The Xn Application Protocol (XnAP) IE or field is included in the XnAP IE, and the inter-node RRC message or XnAP IE is also included. Transfer Request The message states that, alternatively, S-BS 104A determines that a request is needed or that C-BS 106A provides a complete LTM candidate configuration, in which case S-BS 104A does not include the LTM reference configuration. Transfer Request The message states that if the S-BS 104A does not obtain the LTM reference configuration, then the S-BS 104A will not include the LTM reference configuration in the message. Transfer Request In the message. If Transfer Request If the message includes an LTM reference configuration, CU 172 can include the LTM reference configuration in the first CU-DU message. DU 174 can extract the LTM reference DU configuration from the LTM reference configuration. Alternatively, CU 172 extracts the LTM reference DU configuration from the LTM reference configuration and includes the LTM reference DU configuration in the first CU-DU message. DU 174 can generate an incremental configuration based on the LTM reference DU configuration, such as a reference... Figure 3 As described. Alternatively, DU 174 can ignore the LTM reference (DU) configuration and generate the LTM DU configuration as a complete configuration, as described in the reference. Figure 3 As described.

[0140] Otherwise, if Transfer Request If the message does not include an LTM reference configuration, then in some embodiments, CU 172 receives an LTM reference DU configuration from DU 174, such as a reference DU configuration. Figure 3 As described. In other embodiments, CU 172 does not receive an LTM reference DU configuration from DU 174. If CU 172 receives an LTM reference DU configuration (e.g., in a first DU to CU message), then CU 172 generates an LTM reference configuration that includes the LTM reference DU configuration (the LTM reference configuration generated by the C-BS). CU 172 may include an LTM reference CU configuration (the LTM reference CU configuration generated by the candidate CU (C-CU)). Otherwise, if CU 172 does not receive an LTM reference DU configuration from DU 174, as in the reference... Figure 3 As described, CU 172 does not generate an LTM reference configuration. Instead, CU 172 generates an LTM reference configuration (C-BS generated LTM reference configuration) that only includes the LTM reference CU configuration generated by C-CU. When CU 172 generates an LTM reference configuration (C-BS generated LTM reference configuration), CU 172 includes the C-BS generated LTM reference configuration. Confirmation of transfer request In the message.

[0141] In some implementations, if LTM DU configuration 1 is a complete configuration, then CU 172 will generate LTM candidate configuration 1 as a complete configuration. CU 172 may include the complete configuration indication (e.g., BS-to-BS interface protocol field / IE) in... Transfer Request confirm The message indicates that LTM candidate configuration 1 is a complete configuration. In some implementations, the BS-to-BS interface protocol is the Xn application protocol defined in 3GPP specification 38.423. In some implementations, the complete configuration indication is a dedicated field / IE (e.g., LTM-specific) to reduce or eliminate the impact on non-LTM configurations. In other implementations, the complete configuration indication is an existing field / IE defined in 3GPP specification 38.423. Otherwise, if LTM DU configuration 1 is an incremental configuration, CU 172 will generate LTM candidate configuration 1 as an incremental configuration. CU 172 can transfer the complete configuration indication from... Confirmation of transfer request The message excludes LTM candidate configuration 1 as an incremental configuration. Alternatively, CU 172 may include the incremental configuration indication (e.g., the BS-to-BS interface protocol field / IE) in the message. Confirmation of transfer requestThe message indicates that LTM candidate configuration 1 is an incremental configuration. In some implementations, the BS-to-BS interface protocol is the Xn application protocol defined in 3GPP specification 38.423. In some implementations, the incremental configuration indication is a dedicated field / IE (e.g., LTM-specific) to reduce or eliminate the impact on non-LTM configurations. In other implementations, the incremental configuration indication is an existing field / IE defined in 3GPP specification 38.423. In some implementations, the BS-to-BS interface protocol field / IE can have at least two possible values ​​(i.e., a first value and a second value). The BS-to-BS interface protocol field / IE can have a first value to indicate a full configuration indication, and the BS-to-BS interface protocol field / IE can have a second value to indicate an incremental configuration.

[0142] In some implementations, the S-BS 104A is pre-configured with CSI resource configuration (e.g., CSI resource configuration 1 or LTM CSI resource configuration 1) and / or LTM SSB configuration (LTM SSB configuration 1) for the first cell. In other implementations, the S-BS 104A receives the CSI resource configuration and / or LTM SSB configuration from the OAM (Operation, Administration, and Maintenance) node. In yet another implementation, the S-BS 104A receives the CSI resource configuration and / or LTM SSB configuration from the CU 172. For example, the CU 172 includes the CSI resource configuration and / or LTM SSB configuration in... Confirmation of transfer request In the message, in some implementations, CU 172 includes the PCI of the first cell (e.g., PCI 1). Confirmation of transfer request The message states that in order to prepare the first cell as a candidate LTM cell for UE 102, the CU of S-BS 104A and the S-DU of S-BS 104A perform LTM CSI report configuration and / or LTM ID configuration procedures. Figure 5 (Not shown in the diagram), similar to procedure 392. During the LTM CSI report configuration and / or LTM ID configuration process, the CU of S-BS 104A sends the CSI resource configuration and / or LTM SSB configuration to the S-DU of S-BS 104A. In response, the CU of S-BS 104A receives one or more CSI report configurations for UE 102 from the S-DU of S-BS 104A. In some implementations, the CU of S-BS 104A receives the CSI report configuration in a second service DU configuration from the S-DU.

[0143] To prepare a first cell as an LTM candidate cell for UE 102, CU 172 can receive early synchronization information (e.g., early synchronization information 1) for the first cell from DU 174 in a DU-CU message (e.g., a first DU-CU message or an additional DU-CU message). In some implementations, DU 174 sends an additional DU-CU message in response to receiving an additional CU-DU message from CU 172. In other implementations, DU 174 sends an additional DU-CU message in response to receiving a first CU-DU message (e.g., ...). UE context modification requirements (Message). CU 172 includes early synchronization information. Confirmation of transfer request The message includes early synchronization information such as RACH configuration (e.g., RACH configuration 1) and / or at least one TCI state configuration (e.g., TCI state configuration 1). In some implementations, DU 174 includes PDCCH command information for early UL synchronization with the first cell in the early synchronization information or in the DU-to-CU message. CU 172 includes PDCCH command information in... Transfer Request confirm In the message.

[0144] In some implementations, CU 172 assigns an LTM ID (e.g., LTMID 1) for identifying the first LTM candidate configuration and includes the LTM ID in... Confirmation of transfer request In the message. In other implementations, S-BS 104A assigns an LTM ID (e.g., LTM ID 1) to identify the first LTM candidate configuration.

[0145] Received Confirmation of transfer request Following the message (e.g., in response to receiving a handover request confirmation message), the S-BS104A (e.g., the CU of the S-BS104A) sends a first RRC reconfiguration message 518 to the UE 102, including {LTM ID 1, LTM candidate configuration 1} as a tuple, similar to event 318. If Confirmation of transfer request If the message includes an LTM reference configuration, the S-BS104A can include the LTM reference configuration in the first RRC reconfiguration message. If the S-BS 104A in Confirmation of transfer requestIf the message receives CSI Resource Configuration 1, TCI State Configuration 1, RACH Configuration 1, and / or LTM SSB Configuration 1, the S-BS 104A may include this information in the tuple. Alternatively, the S-BS 104A sends one or more additional RRC reconfiguration messages to the UE 102, including CSI Resource Configuration 1, TCI State Configuration 1, RACH Configuration 1, LTM SSB Configuration 1, and / or the PCI of the first cell. In each of the additional RRC reconfiguration messages, the S-BS 104A includes LTM ID 1 to indicate that CSI Resource Configuration 1, TCI State Configuration 1, RACH Configuration 1, LTM SSB Configuration 1, and / or the PCI of the first cell are associated with or configured for the first cell. In response to the first RRC reconfiguration message, the UE 102 sends a 520 First RRC Reconfiguration Complete Message to the S-BS 104A. UE 102 sends an additional RRC reconfiguration completion message to S-BS 104A in response to each of the additional RRC reconfiguration completion messages. The RRC reconfiguration messages (i.e., the first RRC reconfiguration message and / or the additional RRC reconfiguration message) and the RRC reconfiguration completion messages (i.e., the first RRC reconfiguration completion message and / or the additional RRC reconfiguration completion message) form the LTM configuration delivery procedure. S-BS 104A may include the second service DU configuration in the first RRC reconfiguration message or in one of the additional RRC reconfiguration messages.

[0146] In some implementations, if Confirmation of transfer request If the message includes a complete configuration indication indicating that LTM candidate configuration 1 is a complete configuration, then S-BS 104A will include the complete configuration indication (e.g., the RRC field / IE) in the first RRC reconfiguration message to indicate that LTM candidate configuration 1 is a complete configuration. Otherwise, if Confirmation of transfer request The message does not include a complete configuration instruction (or if) Confirmation of transfer request If the message includes an incremental configuration indication that LTM candidate configuration 1 is an incremental configuration, then S-BS104A indicates that LTM candidate configuration 1 is an incremental configuration by excluding the complete configuration indication (e.g., RRC field / IE) from the first RRC reconfiguration message.

[0147] if Confirmation of transfer requestIf the message includes PDCCH command information (PDCCH command information 1), then S-BS 104A sends a 550 PDCCH command based on the PDCCH command information. If S-BS 104A is a distributed base station, then the CU of S-BS 104A can send the PDCCH command information to the S-DU of S-BS 104A. For example, S-BS 104A or its S-DU sends a 550 PDCCH command including the PDCCH command information to UE 102. In some implementations, S-BS 104A or its S-DU can determine the SSB index included in the PDCCH command based on L1 measurement report 524 and / or CSI resource configuration, CSI report configuration, and / or LTM SSB configuration. In some implementations, S-DU or S-BS 104A includes LTM ID 1 in the PDCCH command to indicate the first cell. UE 102 uses RACH configuration and / or PDCCH command information to send a 552 RA preamble to DU 174 on the first cell. S-DU or S-BS 104A derives the TA value based on the RA preamble. DU 174 then sends a 556 RA preamble containing the TA value to CU 172. DU-CU TA Information Transmission Message. CU 172 sends CU-CU TA information transmission message 558, including the TA value, to S-BS 104A (e.g., the CU of S-BS 104A). In some implementations, DU 174 includes cell ID 1, RA preamble index, RA-RNTI, DU ID of S-DU of S-BS 104A, and / or BS ID of S-BS 104A in message 556. In some implementations, DU 174 does not include the BS ID in message 556. In some implementations, CU 172 includes cell ID 1, RA preamble index, RA-RNTI, DU ID of S-DU, and / or BS ID of S-BS 104A in message 558. In some implementations, CU 172 does not include the BS ID in message 558. The CU of S-BS 104A sends to the S-DU of S-BS 104A a message including the TA value, cell ID 1, RA preamble index, RA-RNTI, and / or the DU ID of the S-DU and / or the BSID of the S-BS 104A. CU-DU TA Information Transmission Message. In some implementations, the CU of S-BS 104A does not include the BS ID. CU-DU TA Information Transmission In the message.

[0148] In some implementations, CU 172 determines the address (e.g., IP address) of the S-BS 104A or its CU based on the BS ID of the S-BS 104A. In other implementations, CU 172 determines the address (e.g., IP address) of the S-BS 104A or its CU based on the DU ID of the S-DU of the S-BS 104A. Using these implementations, CU 172 sends data to the S-BS 104A or its CU according to the address. CU-CU TA Information Transmission information.

[0149] In response to determining, for example, based on measurement reports 524 and / or 554, that UE 102 should perform an LTM cell handover to a first cell, S-DU or S-BS 104A sends an LTM cell handover command 526, including LTM ID 1 (e.g., a configuration identifier), to UE 102. In response to the LTM cell handover command, UE 102 may cease communication on the serving cell. In response to the LTM cell handover command, UE 102 accesses the first cell 532 and sends an RRC reconfiguration complete message 536 to DU 174. DU 174 then sends a DU-CU message 538, including the RRC reconfiguration complete message, to CU 172. After receiving the DU-CU message 538 or the RRC reconfiguration complete message, C-BS 106A communicates with UE 102 540 according to the first LTM candidate configuration and / or LTM reference configuration. In some implementations, UE 102 sends an RRC reconfiguration complete message (536) including LTM ID 1 to instruct UE 102 to apply the first LTM candidate configuration. Based on LTM ID 1, CU 172 identifies the first LTM candidate configuration and / or the LTM reference configuration. In other implementations, CU 172 is based on... Connection successful The first cell ID included in message 534 is used to identify the first LTM candidate configuration and / or LTM reference configuration. In this implementation, CU 172 maintains or stores the association information between the first cell ID and the first LTM candidate configuration and / or LTM reference configuration. When CU 172... Connection successful When receiving the first cell ID in the message 534, CU 172 identifies the first LTM candidate configuration and / or LTM reference configuration based on the first cell ID and associated information.

[0150] In some implementations, if the S-DU or S-BS 104A receives a TA value, as described above, the S-DU or S-BS 104A may include the TA value in the LTM cell handover command. In some implementations, the S-DU or S-BS 104A includes the first TCI state ID in the LTM cell handover command. The first TCI state ID indicates the first one in the TCI state configuration.

[0151] In response to the confirmation command UE 102 to perform LTM cell handover or after sending the 526 LTM cell handover command, the S-DU of S-BS 104A sends a message to the CU of S-BS 104A. DU-CU cell handover notification The message indicates that UE 102 is performing or in the process of an LTM cell handover to the first cell. In response to receiving... DU-CU cell handover notification Message: CU of S-BS 104A sends 527 to CU 172 CU-CU cell handover notification The message instructs UE 102 to perform an LTM cell handover to the first cell. In response, CU 172 sends 530 to DU 174. CU-DU Cell Handover Notification The message instructs UE 102 to perform an LTM cell handover to the first cell. In some implementations, S-BS 104A includes the first TCI state ID. CU-CU cell handover Know In the message, CU 172 then includes the first TCI status ID. CU-DU Cell Handover Notification In the message, UE 102 and DU 174 identify the first in the TC state configuration based on the first TCI state ID, and UE 102 and DU 174 apply the first TCI state configuration to communicate UL transmissions and / or DL ​​transmissions in events 532, 536 and / or 540.

[0152] In some implementations, the UE 102 determines whether to perform an LTM cell handover, sends an LTM cell handover command (526), ​​or receives a command (527). DU-CU cell handover notification Following the message (e.g., in response to a confirmation command UE 102 to perform an LTM cell handover, sending a 526 LTM cell handover command, or receiving a 527 cell handover notification message to the DU-CU), the S-BS 104A (e.g., the CU of the S-BS 104A) sends one or more 531 messages to the CU 172. Early state transfer Each early state delivery message includes the DL COUNT value or DISCARD DLCOUNT value of the DRB for data exchanged between UE 102 and S-BS 104A on which they communicate 502 data. In some implementations, upon receiving 534... Connection successfulFollowing the message, or after receiving the 538 DU to CU message or the RRC reconfiguration complete message, CU 172 sends a 539 LTM success message to S-BS 104A (e.g., the CU of S-BS 104A) to indicate that the LTM cell handover was successfully completed. In some implementations, the LTM success message is... Successful handover In some implementations, CU 172 includes the first cell ID in the LTM success message. In other implementations, CU 172 does not send a BS-to-BS message to S-BS 104A (e.g., the CU of S-BS 104A) to indicate that the LTM cell handover was successfully completed.

[0153] In some implementations, the UE 102 is instructed to perform an LTM cell handover, send the LTM cell handover command (526), ​​and receive the command (527). DU-CU cell handover notification After receiving message 539 to LTM success message (e.g., in response to confirming command UE 102 to perform LTM cell handover, sending LTM cell handover command 526, receiving cell handover notification message 527 to DU-CU, or receiving LTM success message 539), S-BS 104A (e.g., the CU of S-BS 104A) sends message 541 to CU 172. SN State transfer The message, the SN status transmission message includes the DRB / DL COUNT value and / or UL COUNT value of the data on which UE 102 and S-BS 104A communicate with each other 502.

[0154] In some implementations, when receiving 534 to Connection successful Message, receive 538 to DU to CU message or RRC reconfiguration complete message or receive 541 to SN status transmission Following the message (e.g., in response to receiving a 534 message to access success, a 538 message to DU to CU, an RRC reconfiguration complete message, or a 541 message to SN status transfer), CU 172 sends 543 to S-BS104A. UE context release Message. Response to UE context release The message indicates that S-BS 104A releases the UE context of UE 102.

[0155] In some implementations, the S-BS 104A (e.g., the CU of the S-BS 104A) may prepare additional cells (i.e., cells 2, ..., N) as LTM candidate cells for UE 102 before or after sending the LTM cell handover command, or during or after procedure 598, as described above. Cells 2, ..., N are identified by cell IDs 2, ..., N, respectively, and are operated by DU 174 and / or other DUs of the C-BS 106A. N is an integer greater than 1. For example, the S-BS 104A and CU 172 perform additional inter-CU LTM preparation procedures 2, ..., N to prepare cells 2, ..., N, respectively. Each of the inter-CU LTM preparation procedures 2, ..., N is similar to procedure 598. In the inter-CU LTM preparation procedures 2, ..., N, the S-BS 104A receives LTM candidate configurations 2, ..., N for LTM, respectively. As described above, S-BS 104A or C-BS106A assigns LTM IDs 2, ..., N to identify LTM candidate configurations 2, ..., N, respectively. S-BS 104A can obtain CSI resource configurations 2, ..., N for cells 2, ..., N, as described for CSI resource configuration 1. S-BS 104A can obtain CSI report configurations 2, ..., N or cells 2, ..., N, as described for CSI report configuration 1. S-BS 104A can obtain RACH configurations 2, ..., N for cells 2, ..., N, as described for RACH configuration 1. S-BS 104A can obtain TCI status configurations 2, ..., N for cells 2, ..., N, as described for TCI status configuration 1. S-BS 104A can obtain LTM SSB configurations 2, ..., N for cells 2, ..., N, as described for LTM SSB configuration 1. The S-BS 104A can obtain PCI 2, ..., N for cells 2, ..., N, as described for PCI 1. In some implementations, the S-BS 104A can perform LTM configuration delivery procedures 2, ..., N with the UE 102 to send the UE 102 lists of {LTM ID 2, LTM candidate configuration 2, CSI resource configuration 2 (if obtained), TCI state configuration 2 (if obtained), RACH configuration 2 (if obtained), LTM SSB configuration 2 (if obtained), PCI 2 (if obtained)}, ..., {LTM ID N, LTM candidate configuration N, CSI resource configuration N, TCI state configuration N (if obtained), RACH configuration N (if obtained), LTM SSB configuration N (if obtained), PCI N (if obtained)}.Each of the LTM configuration delivery procedures 2, ..., N is similar to procedures 394 and / or 494. In other implementations, S-BS 104A includes the list in the first RRC reconfiguration message.

[0156] In other implementations, S-BS 104A and CU 172 perform process 598 to prepare one or more of cell IDs 1, ..., N as LTM candidate cells for UE 102. In this type of implementation, S-BS 104A includes cell IDs 1, ..., N in... Transfer Request Message 505 is used for LTM, as described for cell ID 1. In some implementations, upon receiving... Transfer Request Following the message, CU 172 determines or selects cells 1, ..., N as LTM candidate cells. M is a positive integer and M ≤ N. In other implementations, CU 172, as in... Transfer Request As requested in the message, cells 1, ..., N are prepared for LTM. CU 172 and DU 174 perform LTM preparation procedures 2, ..., M to prepare cells 2, ..., M as LTM candidate cells for UE102, respectively. LTM preparation procedures 2, ..., M are similar to the procedure 590 performed by CU 172 and DU 174 to prepare cell 1. As a result of LTM preparation procedures 2, ..., M, CU 172 obtains LTM candidate configurations 2, ..., M for cells 2, ..., M, similar to obtaining LTM candidate configuration 1. C-BS 106A can generate LTM candidate configurations 2, ..., M as a complete configuration, or generate incremental configurations based on the LTM reference configuration, as described for LTM candidate configuration 1. CU 172 includes LTM candidate configurations 2, ..., M in... Confirmation of transfer request In some implementations, CU 172 or S-BS 104A assigns LTM IDs 2, ..., M to identify LTM preparation processes 2, ..., M, respectively, as described for LTM ID 1. When CU 172 assigns LTM IDs 1, ..., M, CU 172 includes LTM IDs 1, ..., M with LTM candidate configurations 1, ..., M respectively. Confirmation of transfer request The message is as described in reference LTM ID 1 and LTM candidate configuration 1.

[0157] In some implementations, CU 172 obtains early synchronization information 2, ..., M for cells 2, ..., M respectively, as described with reference to early synchronization information 1. CU 172 includes the early synchronization information 2, ..., M in... Confirmation of transfer requestIn some implementations, CU 172 or S-BS 104A obtains CSI resource configurations 2, ..., M for cells 2, ..., M, respectively, as described in CSI resource configuration 1. When CU 172 obtains CSI resource configurations 2, ..., M, CU 172 includes CSI resource configurations 2, ..., M in... Confirmation of transfer request In the message.

[0158] In some implementations, CU 172 or S-BS 104A obtains LTM SSB configurations 2, ..., M for cells 2, ..., M, respectively, as described with reference to LTM SSB configuration 1. When CU 172 obtains LTM SSB configurations 2, ..., M, CU 172 includes LTM SSB configurations 2, ..., M in... Confirmation of transfer request In the message, in some implementations, CU 172 or S-BS104A obtains PCI 2, ..., M for cells 2, ..., M respectively, as described with reference to PCI 1. When CU 172 obtains PCI 2, ..., M, CU 172 includes PCI 2, ..., M in... Confirmation of transfer request In the message.

[0159] In some implementations, CU 172 includes a list of {Cell ID 1, LTM ID 1 (if obtained or optional), LTM candidate configuration 1, CSI resource configuration 1 (if obtained or optional), TCI status configuration 1 (if obtained or optional), early synchronization information 1 (if obtained or optional), LTM SSB configuration 1 (if obtained or optional), PCI 1 (if obtained or optional)}, ..., {Cell ID M, LTM ID M (if obtained or optional), LTM candidate configuration M, CSI resource configuration M (if obtained or optional), TCI status configuration M (if obtained or optional), early synchronization information M (if obtained or optional), LTM SSB configuration M (if obtained or optional), PCI M (if obtained or optional)}. Confirmation of transfer request In the message.

[0160] In some implementations, CU 172 obtains PDCCH command information 2, ..., M for cells 2, ..., M respectively, as described for PDCCH command information 1. In one implementation, CU 172 includes PDCCH command information 2, ..., M in... Confirmation of transfer request In another implementation, CU 172 includes PDCCH command information 2, ..., M in the early synchronization information 2, ..., M, respectively. S-BS 104A can retrieve the information from the early synchronization information 2, ..., M, or from... Please hand over Please confirm. The message obtains RACH configuration 2, TCI status configuration 2 and / or PDCCH command information 2, ..., RACH configuration M, TCI status configuration M and / or PDCCH command information M.

[0161] In some implementations, the S-BS 104A can perform LTM configuration delivery procedures 2, ..., M with the UE 102 to send the UE 102 lists of {LTM ID 2, LTM candidate configuration 2, CSI resource configuration 2 (if obtained), TCI state configuration 2 (if obtained), RACH configuration 2 (if obtained), LTM SSB configuration 2 (if obtained), PCI 2 (if obtained)}, ..., {LTM ID M, LTM candidate configuration M, CSI resource configuration M, TCI state configuration M (if obtained), RACH configuration M (if obtained), LTM SSB configuration M (if obtained), PCI M (if obtained)}. Each of the LTM configuration delivery procedures 2, ..., M is similar to procedures 394 and / or 494. In other implementations, the S-BS 104A includes the list in the first RRC reconfiguration message.

[0162] In some implementations, the S-BS 104A can include the measurement results 1, ..., N for cells 1, ..., N respectively. Transfer Request In the message, S-BS 104A receives measurement results from UE 102. C-BS 106A can select or determine cell 1, ..., M based on measurement results 1, ..., N. In other implementations, C-BS 106A can select or determine cell 1, ..., M based on one or more other factors (e.g., the capacity or load of cell 1, ..., N and / or the maximum number of LTM candidate cells). In one implementation, the maximum number of LTM candidate cells is included... Transfer Request In the message, it states that in another implementation, the maximum number of LTM candidate cells is a predetermined number.

[0163] Next, refer to Figures 6A to 20 Several example methods are discussed. (References) Figures 3 to 5 The provided description may be applicable Figures 6A to 16 Generally speaking, Figures 6A to 20 Similar events in the figures are labeled with similar reference numerals that share two least significant digits, where differences are discussed where appropriate. For example, event 302 is similar to event 602. Apart from the differences shown in the figures and discussed below, any of the other implementations discussed for specific events (e.g., those used for messaging and processing) can be applied to events labeled with similar reference numerals in other figures.

[0164] Figures 6A to 6D This is a message passing sequence diagram for an inter-CU LTM scenario, in which the UE is in the DC (Distributor). First, refer to... Figure 6A In scenario 600A, base station 104B operates as the MN, base station 106A operates as a candidate SN (C-SN), and base station 104A operates as a serving or source SN (S-SN). C-SN 106A includes CU 172 and DU 174. MN 104B may include CU and DU (…). Figure 6A (not shown in the image), and Figure 3 Similar to BS 104A. S-SN 104A may include CU and DU ( Figure 6A (Not shown in the image), similar to C-SN 106A. Scenario 600A is similar to Scenario 500, except that Scenario 600A is an SN scenario where the UE communicates with the MN and SN, while Scenario 500 is an MN scenario.

[0165] Initially, UE 102 communicates with MN 104B and S-SN 104A via DC 602. In some implementations, UE 102 is configured to communicate with the DU of S-SN 104A on cell 124A using a serving DU, and to communicate with the CU of S-SN 104A via the DU of S-SN 104A using a serving CU, similar to event 302. In some implementations, UE 102 may communicate with MN 104B and / or S-SN 104A via DC 602 UL PDU and / or DL ​​PDU, the radio bearers including SRB and / or DRB. MN 104B and / or S-SN 104A may configure radio bearers for UE 102. UE 102 communicates with S-SN 104A via DC on the SCG (i.e., SCG radio resources) configured for communication with UE 102, delivering 602 UL PDUs and / or DL ​​PDUs. UE 102 also communicates with MN 104B via DC on the MCG (i.e., MCG radio resources) according to the MN configuration (i.e., MCG configuration). In some implementations, the serving DU configuration is an SN configuration (i.e., SCG configuration). In the MN configuration, MN 104B configures an MCG that includes at least one serving cell (e.g., cell 124B and / or other cells) operated by MN 104B. In the serving DU configuration, S-SN 104A configures an SCG that includes at least one serving cell (e.g., cell 124A and / or other cells) operated by S-SN 104A. In some implementations, the MN configuration includes multiple configuration parameters, and UE 102 receives these configuration parameters from MN 104B in one or more RRC messages. (See reference...) Figure 3 As described, the service DU configuration includes multiple configuration parameters. In some implementations, UE 102 receives these configuration parameters from S-SN 104A in one or more RRC messages, for example, via MN 104B and / or on an SRB (e.g., SRB3) configured to exchange RRC messages between UE 102 and S-SN 104A in MN 104B or S-SN 104A.

[0166] When communicating with UE 102 via DC through MN 104B, S-SN 104A can perform a CU-in-LTM configuration procedure 696 with UE 102, similar to procedures 396 and / or 496. When communicating with UE 102 via DC through MN 104B, S-SN 104A can perform a CU-in-LTM procedure 680 with UE 102, similar to procedures 380 and / or 480. In procedure 696 or 680, the CU of S-SN 104A can send one or more RRC reconfiguration messages to the UE via SRB3, each RRC reconfiguration message including one or more LTM candidate configurations, similar to procedures 394 or 494. Alternatively, the CU of S-SN 104A can send one or more RRC reconfiguration messages to UE 102 via MN 104B, each RRC reconfiguration message including one or more LTM candidate configurations. In response to each of the RRC reconfiguration messages, UE 102 sends an RRC reconfiguration complete message to S-SN 104A via MN 104B.

[0167] When communicating with MN 104B and S-SN 104A via DC, UE 102 can, for example, send at least one measurement report (604A) directly to S-SN 104A via SRB3, similar to events 304 / 306, 404 / 406, and 504. Alternatively, UE 102 can send the measurement report to MN 104B. MN 104B generates at least one SN message including the measurement report and sends the SN message to CU172. In one implementation, the SN message includes... RRC transmission Messages and / or SN Modification Request The S-SN104A (e.g., the CU of the S-SN 104A) generates a measurement configuration to configure the UE 102 to send measurement reports, and the S-SN104A sends the measurement reports to the UE 102 directly (e.g., via the S-DU of the S-SN 104A) or via the MN 104B.

[0168] After receiving one or more measurement reports from UE 102 (e.g., in response to receiving one or more measurement reports from UE 102), S-SN 104A (e.g., the CU of S-SN 104A) determines a first cell (e.g., cell 126A) as an LTM candidate cell for UE 102. In response to this determination, S-SN 104A generates an SN request message (first SN request message) that includes a first cell ID (e.g., cell ID 1) of the first cell (e.g., cell 1) and / or indicates a target SN ID for C-SN 106A. In some implementations, the SN request message includes an LTM indicator indicating that the SN request message pertains to LTM for the first cell ID. S-SN 104A sends a 603 SN request message to MN 104B. Upon receiving the SN request message (e.g., in response to receiving the SN request message), MN 104B sends SN request message 605, including the first cell ID (first SN request message), to CU 172 to request that a first cell be prepared for UE 102 as an LTM candidate cell. In response to the SN request message, CU 172 and DU 174 perform LTM preparation procedure 690 to prepare the first cell for UE 102 as an LTM candidate cell, similar to procedures 390, 490, or 590. In procedure 690, CU 172 sends a first CU-DU message including the first cell ID to DU 174 to request preparation of the first cell, similar to event 385. In response, CU 172 can receive a first DU-CU message including LTMDU configuration 1 from DU 174, similar to event 310. CU 172 generates a first LTM candidate configuration (LTM candidate configuration 1). In response to the SN request message, CU 172 sends an SN request confirmation message (e.g., a first SN request confirmation message) containing a first LTM candidate configuration to MN 104B, which is 607. In some implementations, CU 172 includes a first cell ID in the SN request confirmation message to indicate that the first LTM candidate configuration is provided for or associated with a first cell (e.g., ID or first cell ID). MN 104B sends an SN confirmation message (e.g., a first SN confirmation message) containing a first LTM candidate configuration to S-SN 104A, which is 609A. In some implementations, MN 104B includes a first cell ID in the SN confirmation message to indicate that the first LTM candidate configuration is provided for or associated with a first cell (ID).

[0169] Events 603, 605, 690, 607, and 609A are in Figure 6A This is collectively referred to as the SN-initiated SN-inter-SN LTM preparation process 698A.

[0170] In some implementations, the SN requirement message and the SN confirmation message are respectively SN changed requirements Messages and SN changes confirmed certificate Message. In other implementations, the SN requirement message and the SN confirmation message are respectively SN Modification Requirements Messages and SN modification confirmed certificate Messages. In some implementations, the SN request message and the SN request acknowledgment message are respectively... SN Add Request Messages and SN Add Add confirmation request Messages. In other implementations, the SN request message and the SN request confirmation message are respectively SN Modification Request Messages and SN modification request confirmation information.

[0171] In some implementations, the SN request message includes the DU ID of the S-DU of S-SN 104A. In this case, MN104B may include the DU ID in the SN request message, and CU 172 may include the DU ID in the first CU to DU message. In other implementations, the SN request message includes the first BS ID of S-SN 104A. In some implementations, MN104B may include the first BS ID in the SN request message. When the first BS ID is received, CU 172 may include the first BS ID in the first CU to DU message. In some implementations, MN 104B may include its second BS ID in the SN request message. When the second BS ID is received, CU 172 may include the second BS ID in the first CU to DU message. In some implementations, the first BS ID and the second BS ID are gNB IDs.

[0172] In some implementations, CU 172 requests the LTM reference DU configuration in procedure 690, such as the reference... Figure 3 , Figure 4 and Figure 5 As described. In other implementations, CU 172 does not request the LTM reference DU configuration in process 690. In some implementations, DU 174 sends the LTM reference DU configuration to CU 172 in process 690, as reference Figure 3 , Figure 4 and Figure 5 As described. In other implementations, DU 174 does not send the LTM reference DU configuration to CU 172 in process 690. In some implementations, S-SN104A (e.g., the CU of S-SN 104A) can obtain the LTM reference configuration, such as reference Figure 3 and Figure 4As described. In other implementations, S-SN 104A can be from MN 106B during the LTM preparation process between another SN ( Figure 6A (Not shown) Receives the LTM reference configuration, as described above and below. If S-SN 104A obtains the LTM reference configuration, S-SN 104A may include the LTM reference configuration (the LTM reference configuration generated by S-SN) in the SN request message. Subsequently, MN 104B includes the LTM reference configuration in the SN request message. Alternatively, S-SN 104A determines to request or cause C-SN 106A to provide a complete LTM candidate configuration, such that S-SN 104A does not send the LTM reference configuration to C-SN 106A. If S-SN 104A does not obtain the LTM reference configuration, S-SN 104A does not include the LTM reference configuration in the SN request message. If the SN request message includes the LTM reference configuration, MN 104B includes the LTM reference configuration in the SN request message. Otherwise, if the SN request message does not include the LTM reference configuration, MN 104B may not include the LTM reference configuration in the SN request message.

[0173] If the SN request message includes an LTM reference configuration, as described above, then CU 172 may include the LTM reference configuration in the first CU-DU message. Alternatively, CU 172 may extract an LTM reference DU configuration from the LTM reference configuration and include the LTM reference DU configuration in the first CU-DU message. Otherwise, if the SN request message does not include an LTM reference configuration, in some embodiments, CU 172 receives the LTM reference DU configuration from DU 174, as described above. Figure 3 As described. In other embodiments, CU 172 does not receive an LTM reference DU configuration from DU 174. If CU 172 receives an LTM reference DU configuration (e.g., in a first DU to CU message), then CU 172 generates an LTM reference configuration that includes the LTM reference DU configuration (an LTM reference configuration generated by the C-SN). CU 172 may include an LTM reference CU configuration (an LTM reference CU configuration generated by a candidate CU (C-CU)). Otherwise, if CU 172 does not receive an LTM reference DU configuration from DU 174, as in the reference... Figure 3 As described, CU 172 does not generate an LTM reference configuration. Instead, CU 172 generates an LTM reference configuration (C-SN generated LTM reference configuration) that only includes the LTM reference CU configuration generated by C-CU. When CU 172 generates an LTM reference configuration (C-SN generated LTM reference configuration), CU 172 includes the C-SN generated LTM reference configuration in the SN request confirmation message.

[0174] In some implementations, the S-SN 104A can be used in conjunction with, as mentioned in the previous references. Figure 5 The S-BS 104A described is similarly configured, except that some configurations are provided in the SN message instead of the handover message. In some implementations, the S-SN 104A receives CSI resource configuration and / or LTM SSB configuration from the CU 172. For example, the CU 172 includes the CSI resource configuration and / or LTM SSB configuration in the SN request confirmation message. In this case, the MN 104B can include the CSI resource configuration and / or LTM SSB configuration in the SN confirmation message. In some implementations, the CU 172 includes the PCI of the first cell in the SN request confirmation message. In this case, the MN 104B can include the PCI of the first cell in the SN confirmation message. To prepare the first cell as a candidate LTM cell for UE 102, the CU of the S-SN 104A performs the LTMCSI report configuration and / or LTM ID configuration procedure with the S-DU of the S-SN 104A. Figure 6A (Not shown in the diagram), similar to procedures 392 or 492. During the LTM CSI report configuration and / or LTM ID configuration process, the CU of S-SN 104A sends the CSI resource configuration and / or LTM SSB configuration to the S-DU of S-SN 104A. In response, the CU of S-SN 104A receives one or more CSI report configurations for UE 102 from the S-DU of S-SN 104A. In some implementations, S-SN 104A receives a second service DU configuration including the CSI report configuration.

[0175] In some implementations, CU 172 receives early synchronization information and / or PDCCH command information for the first cell from DU 174, as shown in reference [reference]. Figure 5 As described. CU 172 includes early synchronization information and / or PDCCH command information in the SN request confirmation message. MN 104B includes early synchronization information and / or PDCCH command information in the SN confirmation message.

[0176] In some implementations, CU 172 assigns an LTM ID (e.g., LTMID 1) to identify the first LTM candidate configuration, and CU 172 includes the LTM ID and / or its associated (or mapped) cell ID in the SN request confirmation message. MN 104 includes the LTM ID and / or its associated (or mapped) cell ID in the SN confirmation message. In other implementations, S-SN 104A assigns an LTM ID (e.g., LTMID 1) to identify the first LTM candidate configuration. In yet another implementation, MN 104B assigns an LTM ID (e.g., LTMID 1) to identify the first LTM candidate configuration. In such cases, MN 104B may include the LTM ID in the SN confirmation message. After receiving or assigning an LTM ID, the CU of S-SN 104A sends the LTM ID and the first cell ID to the S-DU during the LTM ID configuration process, similar to procedures 390, 392, or 492.

[0177] Upon receiving the SN confirmation message (e.g., in response to receiving the SN confirmation message), S-SN 104A (e.g., the CU of S-SN 104A) performs a 694A LTM ​​configuration delivery procedure with UE 102 to send the LTM ID and LTM candidate configuration to UE 102. In some implementations, S-SN 104A sends {LTM ID, LTM candidate configuration} as a tuple in the first RRC reconfiguration message during procedure 694A. Depending on the implementation, S-SN 104A may include the LTM reference configuration, CSI report configuration, CSI resource configuration, RACH configuration, TCI state configuration, LTM SSB configuration, and / or the PCI of the first cell for UE 102 in the first RRC reconfiguration message and / or other RRC reconfiguration messages sent to UE 102, such as the reference configuration. Figure 3 and Figure 4As described. S-SN 104A includes the LTM ID in the first RRC reconfiguration message or other RRC reconfiguration messages to indicate that the CSI resource configuration, RACH configuration, TCI state configuration, LTM SSB configuration, and / or the PCI of the first cell are associated with the first cell. For example, S-SN 104A includes the CSI resource configuration, RACH configuration, TCI state configuration, LTM SSB configuration, and / or the PCI of cell 1 in a tuple. In another example, S-SN 104A includes {LTM ID 1, CSI resource configuration, RACH configuration, TCI state configuration, LTM SSB configuration, and / or the PCI of cell 1} as a tuple in other RRC reconfiguration messages. In response to each of the other RRC reconfiguration messages, UE 102 sends an RRC reconfiguration complete message to CU 172 via S-DU 174A.

[0178] In some implementations, if the SN request message includes a full configuration indication indicating that LTM candidate configuration 1 is a full configuration, then S-SN 104A includes the full configuration indication (e.g., the RRC field / IE) in the first RRC reconfiguration message to indicate that LTM candidate configuration 1 is a full configuration. Otherwise, if the SN request message does not include a full configuration indication, or if the SN request message includes an incremental configuration indication indicating that LTM candidate configuration 1 is an incremental configuration, then S-SN 104A excludes or does not include the full configuration indication (e.g., the RRC field / IE) from the first RRC reconfiguration message to indicate that LTM candidate configuration 1 is an incremental configuration.

[0179] If the SN confirmation message includes PDCCH command information (PDCCH command information 1), then S-SN 104A can send a 650A PDCCH command to UE 102 based on the PDCCH command information. If S-SN 104A is a distributed base station, then the CU of S-SN 104A can send the PDCCH command information to the S-DU of S-SN 104A, and the S-DU can send a 650A PDCCH command to UE 102. For example, S-SN 104A or its S-DU sends a 650A PDCCH command including the PDCCH command information to UE 102. In some implementations, S-SN 104A or its S-DU can determine to send the PDCCH command based on (e.g., in response to) measurement report 624A. In some implementations, the S-SN 104A or S-DU can determine the SSB index included in the PDCCH command based on the L1 Measurement Report 624A and / or CSI resource configuration, CSI report configuration, and / or LTM SSB configuration. In some implementations, the S-DU or S-SN 104A includes LTM ID 1 in the PDCCH command to indicate the first cell. UE102 uses the RACH configuration and / or PDCCH command information to send a 652 RA preamble to DU 174 on the first cell. The S-DU or S-SN 104A derives the TA value based on the RA preamble. DU 174 sends a 656 command including the TA value to CU 172. DU-CU TA Information transfer Message. CU 172 sends 657 including the TA value to MN 104B (e.g., the CU of MN 104B). CU-CU TA Information Transmission Message. MN 104B sends 658 including the TA value to S-SN 104A. CU-CU TA Information Transmission Message. In some implementations, DU 174 includes cell ID 1, RA preamble index, RA-RNTI, and / or the DU ID of the S-DU of S-SN 104A in message 656. DU 174 may additionally include a first BS ID and / or a second BS ID in message 656. In some implementations, CU 172 includes cell ID 1, RA preamble index, RA-RNTI, and / or the DU ID of the S-DU in message 657. In some implementations, CU 172 may additionally include a first BS ID and / or a second BS ID in message 657. In at least these implementations, MN 104B includes cell ID 1, RA preamble index, RA-RNTI, and / or the DU ID of the S-DU in message 658. In some implementations, MN 104B may additionally include a first BS ID and / or a second BS ID in message 658.

[0180] In some implementations, CU 172 determines the address (e.g., IP address) of MN 104B or its CU based on a second BS ID. Therefore, CU 172 sends message 657 to MN 104B based on the address. In some implementations, MN 104B determines the address (e.g., IP address) of S-SN 104A or its CU based on a first BS ID. In other implementations, MN 104B determines the address (e.g., IP address) of S-SN 104A or its CU based on the DU ID of S-DU of S-SN 104A. In at least these implementations, MN 104B sends message 658 to S-SN 104A or its CU based on the address. CU-CU TA Information Transmission information.

[0181] In response to determining, for example, based on L1 measurement reports 624A and / or 654A, that UE 102 is to perform an LTM cell handover to a first cell, S-DU or S-SN 104A sends an LTM cell handover command 626A to UE 102, including LTM ID 1 (e.g., a configuration identifier). In response to the LTM cell handover command, UE 102 may cease communication on the serving cell. In response to the LTM cell handover command, UE 102 accesses the first cell 632, and UE 102 sends an RRC reconfiguration complete message 636A to DU 174. DU 174 then sends a DU-CU message 638, including the RRC reconfiguration complete message, to CU 172. In some alternative implementations, UE 102 sends the RRC reconfiguration complete message to C-SN 106A via MN 104B instead of via DU 174. After receiving the DU-CU message 638 or the RRC reconfiguration complete message, C-SN 106A communicates 640 with UE 102, which is in the same DC as MN 104B and C-SN 106A, according to the first LTM candidate configuration and / or LTM reference configuration. In some implementations, UE 102 includes LTM ID 1 in the RRC reconfiguration complete message 636A to instruct UE 102 to apply the first LTM candidate configuration. Based on LTM ID 1, CU 172 identifies the first LTM candidate configuration and / or LTM reference configuration. In other implementations, CU 172 is based on... Connection successful The first cell ID included in message 634 is used to identify the first LTM candidate configuration and / or LTM reference configuration. In at least these implementations, CU 172 maintains or stores the association information between the first cell ID and the first LTM candidate configuration and / or LTM reference configuration. When CU 172... Connection successfulWhen the first cell ID is received in the message, CU 172 identifies the first LTM candidate configuration and / or LTM reference configuration based on the first cell ID and associated information.

[0182] In some implementations, if the S-DU or S-SN 104A receives a TA value, as described above, the S-DU or S-SN 104A may include the TA value in the LTM cell handover command. In some implementations, the S-DU or S-SN 104A may include a first TCI state ID in the LTM cell handover command. The first TCI state ID indicates the first one in the TCI state configuration.

[0183] In response to the confirmation command UE 102 to perform LTM cell handover or in response to sending the 626A LTM ​​cell handover command, the S-DU of S-SN 104A sends a message to the CU of S-SN 104A. DU-CU cell handover notification The message instructs UE 102 to perform an LTM cell handover to the first cell. In response to receiving... DU-CU cell handover notification Message: The CU of S-SN 104A sends a 627A to MN104B. CU-CU cell handover notification The message instructs UE 102 to perform or be performing an LTM cell handover to the first cell. In response, MN 104B sends 628 to CU 172. CU-CU cell handover notification The message instructs UE 102 to perform or be performing an LTM cell handover to the first cell. In response, CU 172 sends 630 to DU 174. CU-DU cell switching Change notification The message instructs UE 102 to perform or be performing an LTM cell handover to the first cell. In some implementations, S-SN 104A includes the first TCI state ID. CU-CU cell handover notification In message 627A. In this case, MN104B includes the first TCI state ID. CU-CU cell handover notification In message 628, CU 172 then includes the first TCI status ID. CU-DU Cell Handover Notification In the message, UE 102 and DU 174 identify the first in the TC state configuration based on the first TCI state ID, and UE 102 and DU 174 apply the first TCI state configuration to communicate UL transmissions and / or DL ​​transmissions in events 632, 636A and / or 640.

[0184] In some implementations, after determining whether to instruct UE 102 to perform an LTM cell handover or to send a 626A LTM ​​cell handover command (e.g., in response to determining whether to instruct UE 102 to perform an LTM cell handover or to send a 626A LTM ​​cell handover command), S-SN 104A sends one or more 631 commands to MN 104B. Early state transferEach early state delivery message includes the DL COUNT value of the DRB or the DISCARD DL COUNT value of the data that UE 102 and S-SN 104A communicate with each other on. MN 104B sends one or more DL COUNT values ​​to CU 172. Early state transfer Each early state delivery message includes the DL COUNT value of the DRB or the DISCARD DL COUNT value of the UE 102 and S-SN 104A communicating with each other on 602 data.

[0185] In some implementations, when receiving 634 to Connection successful After receiving a 638 message (DU to CU) or an RRC reconfiguration complete message, CU 172 sends a 639 LTM success message to MN 104B (e.g., to the CU of MN 104B) to indicate that the LTM cell handover was successfully completed. In some implementations, the LTM success message is... SN Modification Requirements The message is either a BS-to-BS access success message. In some implementations, CU 172 includes the first cell ID in the LTM success message. In other implementations, CU 172 does not send a BS-to-BS message to MN 104B (e.g., the CU of MN 104B) to indicate that the LTM cell handover has been successfully completed. In some implementations, after receiving the LTM success message or receiving the RRC reconfiguration completion message from UE 102 (e.g., in response to receiving the LTM success message or receiving the RRC reconfiguration completion message from UE 102), MN 104B may send an SN message (e.g., ...) to S-SN 104A. Figure 6C (As shown in event 645). The SN message can indicate that the LTM cell handover has been successfully completed, and S-SN 104A will suspend communication with UE 102, or S-SN 104A will release the UE context and resources configured for UE 102. MN 104B can include the first cell ID in the SN message. In some implementations, the SN message is... SN Modification Request information, SN release request Messages, SN access success messages, etc.

[0186] In some implementations, the UE 102 is instructed to perform LTM cell handover, send the 626A LTM ​​cell handover command, and receive the command from the S-DU. DU-CU cell handover notification After receiving the SN message (e.g., in response to a confirmation command UE 102 to perform LTM cell handover, sending the 626A LTM ​​cell handover command, receiving the DU-CU cell handover notification message from the S-DU, or receiving the SN message), S-SN 104A (e.g., the CU of S-SN 104A) sends 641 to MN 104B. SN status transmission The message, the SN status transmission message, includes the DRB / DL COUNT value and / or UL COUNT value of the data 602 that UE 102 and S-SN 104A communicate with each other on. Upon receiving SN status transmission Following message 641 (e.g., in response to receiving SN status transmission message 641), MN 104B sends message 642 to CU 172, including the DL COUNT value and / or the UL COUNT value. SN State transfer information.

[0187] In some implementations, S-SN 104A (e.g., the CU of S-SN 104A) can communicate with MN 104B and one or more C-SNs (including C-SN 106A) before or after sending an LTM cell handover command, or during or after process 698A, as described above, in accordance with reference. Figure 3 A similar approach is described where UE 102 prepares additional cells (i.e., cells 2, ..., N) as LTM candidate cells, except that the LTM preparation process can be inter-SN and is similar to process 698A. As described above, MN 104B, S-SN 104A, or C-SN assigns LTM IDs 2, ..., N to identify LTM candidate configurations 2, ..., N, respectively. Each of the LTM configuration delivery processes 2, ..., N is similar to process 394 or 494. In other implementations, S-SN 104A includes the tuple in the first RRC reconfiguration message.

[0188] In some implementations, the SN request message and SN confirmation message in each of the SN-to-SN LTM preparation processes 2, ..., N respectively include an SN modification request message and an SN modification confirmation message. In other implementations, the SN request message and SN confirmation message in each of the SN-to-SN LTM preparation processes 2, ..., N respectively include an SN change request message and an SN change confirmation message. In some implementations, the SN request message and SN request confirmation message in each of the SN-to-SN LTM preparation processes 2, ..., N respectively include... SN Add Request Messages and SN Add Request Confirmation Messages. In other implementations, the SN request message and SN request confirmation message in each of the SN-to-SN LTM preparation processes 2, ..., N respectively include... SN Modification Request Messages and SN modification request confirmationIn some implementations, the information provided in the SN confirmation message (e.g., LTM candidate configuration, LTM reference configuration, first cell ID, or LTM ID) is instead provided in the SN modification request message from MN 104B to S-SN 104A (i.e., similar to event 609B, which will be discussed below regarding...). Figure 6B (Scene 600B is described in the text).

[0189] In other implementations, S-SN 104A and CU 172 perform process 698A to prepare cell 1 and cell 2, ..., N (one or more of them) as LTM candidate cells for UE 102. Cell 2, ..., N are identified by cell ID 2, ..., N respectively, and the cells are operated by DU 174 and / or other DUs of C-SN 106A. In such implementations, S-SN 104A includes cell ID 2, ..., N in the SN request message 603 for LTM, and MN 104B includes cell ID 2, ..., N in the SN request message as described above for cell ID 1. In some implementations, upon receiving the SN request message, CU 172 determines or selects cell 1, ..., M from cells 1, ..., N as LTM candidate cells. M is a positive integer and M≤N. In other implementations, CU 172 prepares cells 1, ..., N for LTM as requested in the SN request message. CU 172 and DU 172 perform LTM preparation procedures 2, ..., M to prepare cells 2, ..., M as LTM candidate cells for UE 102, respectively. LTM preparation procedures 2, ..., M are similar to the procedure 690 performed by CU 172 and DU 174 to prepare cell 1. As a result of LTM preparation procedures 2, ..., M, CU 172 obtains LTM candidate configurations 2, ..., M for cells 2, ..., M, similar to obtaining LTM candidate configuration 1. C-SN 106A can generate LTM candidate configurations 2, ..., M as a complete configuration, or C-SN 106A can generate incremental configurations based on the LTM reference configuration, as described for LTM candidate configuration 1. CU 172 includes LTM candidate configurations 2, ..., M in the SN request confirmation message. In some implementations, CU 172, MN104B, or S-SN 104A assigns LTM IDs 2, ..., M to identify LTM preparation processes 2, ..., M, respectively, as described for LTM ID1 and LTM candidate configuration 1. When CU 172 assigns LTM IDs 1, ..., M, CU 172 includes LTM IDs 1, ..., M and LTM candidate configurations 1, ..., M in the SN request confirmation message, respectively, as described for LTM ID1 and LTM candidate configuration 1.

[0190] In some implementations, CU 172 obtains early synchronization information 2, ..., M for cells 2, ..., M respectively, as described for early synchronization information 1. CU 172 includes the early synchronization information 2, ..., M in the SN request confirmation message. In some implementations, CU 172 or S-SN 104A obtains CSI resource configurations 2, ..., M for cells 2, ..., M respectively, as described for CSI resource configuration 1. When CU 172 obtains CSI resource configurations 2, ..., M, CU 172 includes the CSI resource configurations 2, ..., M in the SN request confirmation message.

[0191] In some implementations, CU 172 or S-SN 104A obtains LTM SSB configurations 2, ..., M for cells 2, ..., M, as described for LTM SSB configuration 1. When CU 172 obtains LTM SSB configurations 2, ..., M, CU 172 includes LTM SSB configurations 2, ..., M in the SN request confirmation message. In some implementations, CU 172 or S-SN 104A obtains PCI 2, ..., M for cells 2, ..., M, as described for PCI 1. When CU 172 obtains PCI 2, ..., M, CU 172 includes PCI 2, ..., M in the SN request confirmation message.

[0192] In some implementations, CU 172 will be similar to the one described earlier in this article. Confirmation of transfer request Lists similar to those provided in message 507 are included in SN request confirmation messages. MN 104B includes a list or a portion of a list in SN confirmation messages.

[0193] In some implementations, CU 172 obtains PDCCH command information 2, ..., M for cells 2, ..., M respectively, as described for PDCCH command information 1. In one implementation, CU 172 includes PDCCH command information 2, ..., M in the SN request confirmation message. In another implementation, CU 172 includes PDCCH command information 2, ..., M in the early synchronization information 2, ..., M respectively. MN 104B may include PDCCH command information 2, ..., M in the SN confirmation message, as described with reference to PDCCH command information 1. S-SN 104A may obtain RACH configuration 2, TCI status configuration 2 and / or PDCCH command information 2, ..., RACH configuration M, TCI status configuration M and / or PDCCH command information M respectively from early synchronization information 2, ..., M or from the SN confirmation message.

[0194] In some implementations, the S-SN 104A can perform LTM configuration delivery procedures 2, ..., M, similar to procedures 394 and / or 494. In other implementations, the S-SN 104A includes the tuple in the first RRC reconfiguration message.

[0195] In some implementations, MN 104B can include the measurement results 1, ..., N for cells 1, ..., N in the SN request message, as described above. Transfer Request The message is similar.

[0196] Events 626A, 627A, 628, 630, 631, 632, 633, and 634 are in Figure 6A This is collectively referred to as LTM execution process 699.

[0197] Next reference Figure 6B Scenario 600B is largely similar to Scenario 600A, except that it includes events 604B, 609B, and 611 instead of events 603 and 609A. In Scenario 600B, MN 104B initiates the 698B inter-SN LTM preparation procedure, while in Scenario 600A, S-SN 104A initiates the 698A inter-SN LTM preparation procedure. When communicating with MN 104B and S-SN 104A via DC, UE 102 can send at least one measurement report of 604B to MN 104B, for example, via SRB1, similar to events 304 / 306, 404 / 406, and 504. If MN 104B is a distributed base station, it includes CU and DU. The CU of MN 104B receives measurement reports from UE 102 via the DU of MN 104B. MN 104B (e.g., CU of MN 104B) generates a measurement configuration to configure UE 102 to send a measurement report, and MN 104B sends the measurement configuration to UE 102 (e.g., via DU of MN 104B).

[0198] After receiving one or more measurement reports from UE 102 (e.g., in response to receiving one or more measurement reports from UE 102), MN 104B (e.g., the CU of MN 104B) determines to prepare a first cell (e.g., cell 124B) as an LTM candidate for UE 102. In response to this determination, MN 104B generates an SN request message (e.g., a first SN request message) including a first cell ID (e.g., cell ID 1) of the first cell (e.g., cell 1) and sends a 605 SN request message to C-SN 106A. In response to the SN request message, CU 172 determines to perform an LTM preparation process 690 with DU 174, and CU 172 sends a 607 SN request confirmation message to MN 104B, as referenced. Figure 6A As described. After receiving message 607 (e.g., in response to receiving message 607), MN 104B sends 609B to S-SN 104A, including the first LTM candidate configuration (LTM candidate configuration 1), the LTM reference configuration, and / or the first cell ID. SN Modification Request The message is similar to Event 609A. If the SN request confirmation message includes LTM-related configurations for configuring the first cell as an LTM candidate cell, such as RACH configuration, TCI state configuration, CSI resource configuration, LTM SSB configuration, and / or the PCI of the first cell, then MN 104B will include the LTM-related configurations in the message. SN Modification Request In the message. Response to SN Modification Request Message: S-SN 104A sends 611 to MN 104B SN Repair Confirmation of the request The message, and performs the 694 LTM configuration delivery procedure with UE 102 to send the first LTM candidate configuration and / or LTM reference configuration to UE 102. Events 605, 690, 607, 609B and 611 in Figure 6B This is collectively referred to as the MN-initiated SN-interval LTM preparation process 698B.

[0199] For reference Figure 6A As described, the SN request confirmation message 607 may include PDCCH command information. If the SN request confirmation message 607 includes PDCCH command information, then MN 104B will include the PDCCH command information in... SN Modification Request In the message. If SN Modification Request If the message includes PDCCH command information, then S-SN 104A can send a 650A PDCCH command to UE 102 based on the PDCCH command information, as shown in the reference. Figure 6A As described. If SN Modification RequestIf the message includes TCI status configuration, then the S-SN104A can include the first TCI status ID in the LTM cell handover command, as shown in the reference. Figure 6A As described.

[0200] In some implementations, MN 104B (e.g., the CU of MN 104B) may perform one or more LTM preparation procedures with CU 172 or other C-SNs to prepare additional cells (i.e., cell 2, ..., N) as LTM candidate cells for UE 102, and each of the LTM preparation procedures is similar to procedure 698B. MN 104B may perform the LTM preparation procedure before or after sending the LTM cell handover command, or during, before or after procedure 698B.

[0201] In other implementations, MN 104B and CU 172 perform process 698B to prepare one or more of cell 1 and cell 2, ..., N as LTM candidate cells for UE 102. N is an integer greater than 1. Cell 2, ..., N are identified by cell ID 2, ..., N respectively, and are operated by DU 174 and / or other DUs of C-SN 106A. In this type of implementation, MN 104B includes cell ID 2, ..., N in SN request message 605, as described above with reference to cell ID 1.

[0202] Next reference Figure 6C Scenario 600C is largely similar to scenarios 600A and 600B, except that it includes events 694C, 636C, and 645 instead of events 694A, 636A, and 638. In scenario 600C, MN 104B, in LTM configuration delivery procedure 694C, sends a second serving DU configuration (including CSI report configuration), LTM ID, first LTM candidate configuration, LTM reference configuration, CSI resource configuration, LTM SSB configuration, RACH configuration, TCI state configuration, and / or the PCI of the first cell to UE 102 in one or more RRC reconfiguration messages to configure the first cell as an LTM candidate cell, similar to procedures 394 or 494. In some implementations, MN 104B generates the RRC reconfiguration message in procedure 694C, while S-SN 104A generates the RRC reconfiguration message in procedure 694A. In some implementations, MN 104B assigns LTM IDs in scenario 600C, while S-SN104A assigns LTM IDs in scenarios 600A and 600B.

[0203] When UE 102 performs the 699 LTM execution procedure, UE 102 sends a 636C RRC reconfiguration message to MN 104B, similar to event 636A. In some implementations, UE 102 includes the LTM ID in the RRC reconfiguration completion message to indicate that UE 102 applies the first LTM candidate configuration. After receiving the RRC reconfiguration message (e.g., in response to receiving the RRC reconfiguration message), MN 104B may send a 645 SN message to S-SN 104A, as referenced. Figure 6A As described. In some implementations, the MN 104B may include the first cell ID of the first cell in the SN message. The MN 104B may determine the first cell ID based on the LTM ID received in the RRC reconfiguration complete message.

[0204] Next reference Figure 6D Scene 600D is largely similar to scenes 600A, 600B, and 600C, except that scene 600D includes events 624D, 650D, 654D, and 626D instead of events 624A, 650A, 654A, and 626A. Events 624D, 650D, 654D, and 626D are similar to events 624A, 650A, 654A, and 626A, respectively. The difference is that MN 104B implements or participates in events 624D, 650D, 654D, and 626D, while S-SN 104A implements or participates in events 624A, 650A, 654A, 626A, and 627A.

[0205] In some implementations, MN 104B can generate a CSI report configuration based on CSI resource configuration, as described for S-SN 104A. The CSI resource configuration is configured in the RS transmitted on the first cell. MN 104B sends the CSI report configuration to UE 102 in procedure 694C. In some implementations, MN 104B is pre-configured with CSI resource configuration. In other implementations, MN 104B receives CSI resource configuration from the OAM node. In still other implementations, MN 104B receives CSI resource configuration from CU 172 or S-SN 104A.

[0206] Next, refer to Figures 7A to 17 This section discusses several example methods for LTM operating in RAN nodes (e.g., base stations, DUs, or CUs) or UEs. Generally speaking, for... Figures 3 to 6D Similar events described in Figures 7A to 17Similar reference numerals are used in the figures to refer to events that share two least significant digits, with differences discussed where appropriate. For example, event 302 is similar to events 402, 502, 602, 802, etc. Apart from the differences shown in the figures and discussed below, any of the alternative embodiments discussed for specific events (e.g., those used for messaging and processing) can be applied to events labeled with similar reference numerals in other figures.

[0207] Figure 7A This shows that it can be generated by S-SN (e.g., Figures 6A to 6D Example method 700A is implemented using S-SN 104A. Method 700A begins at block 702, where the S-SN communicates with the UE in the same MN and the DC where the S-SN is located. At block 780, the S-SN may perform at least one in-SN LTM configuration and / or execution procedure with the UE (e.g., event 696 or 680). At block 760, the S-SN determines a first cell for preparing a C-SN for the UE as an LTM candidate cell. At block 703, the S-SN sends an SN request message to the MN to request the preparation of a first cell for LTM. At block 709A, the S-SN receives an SN confirmation message from the MN including a first LTM candidate configuration for the first cell used for LTM. At block 762, the S-SN assigns a first configuration ID (e.g., configuration identifier) ​​to identify the first LTM candidate configuration. At block 718, the S-SN sends a first RRC message to the UE including the first LTM candidate configuration and the first configuration ID. At block 726, the S-SN can send an LTM cell handover command to the UE, which instructs the UE to perform an LTM cell handover to a first cell. The LTM cell handover command may include an LTM ID or a configuration identifier. At block 727, the S-SN can send a CU to the MN. Cell handover notification The CU-to-CU cell handover notification message notifies the S-SN to initiate the transmission of an LTM cell handover command to UE 102 for the LTM cell handover to the first cell. At block 731, the S-SN can send... Early state transfer The early state delivery message includes the DL COUNT value of the DRB or the DISCARD DL COUNT value of the data on which the UE and S-BS communicate with each other. At box 741, the S-SN may send the UL COUNT value and / or DL ​​COUNT value of the DRB to the MN. SN status transmission information.

[0208] In some implementations, the intra-SN LTM configuration and / or execution process includes intra-SN DU LTM configuration and / or execution processes similar to processes 396 or 380. In other implementations, the intra-SN LTM configuration and / or execution process includes intra-SN DU LTM configuration and / or execution processes similar to processes 496 or 480.

[0209] In some implementations, the S-SN includes the first configuration ID in the SN request message. In other implementations, the S-SN does not include the first configuration ID in the SN request message. In some implementations of block 718, the S-SN generates a first LTM configuration including a first LTM candidate configuration and a first configuration ID, and includes the first LTM configuration in a first RRC message. In some implementations, the SN request message (i.e., the first SN request message) includes the first cell ID of the first cell. In some implementations, the SN confirmation message (i.e., the first SN confirmation message) includes the first cell ID in response to an SN request including the first cell ID.

[0210] In some implementations, when or after preparing the first cell for LTM, the S-SN can prepare a second cell of the C-SN (i.e., the first C-SN) as an LTM candidate cell for the UE by sending a second SN request message to the MN, similar to box 703. In response, the S-SN receives a second SN confirmation message from the MN including a second LTM candidate configuration for the second cell used for LTM, similar to box 709A. The S-SN assigns a second configuration ID to identify the second LTM candidate configuration, similar to box 762. In one implementation, the S-SN includes the second LTM candidate configuration and the second configuration ID in a first RRC message. In another implementation, the S-SN sends a second RRC message to the UE including the second LTM candidate configuration and the second configuration ID, similar to box 718. In some implementations, the second SN request message includes the second cell ID of the second cell. In some implementations, the second SN confirmation message includes the second cell ID in response to the second SN request including the second cell ID.

[0211] In some implementations, when or after preparing the first cell for LTM, the S-SN can prepare a third cell of another C-SN (i.e., a second C-SN) as an LTM candidate cell for the UE by sending a third SN request message to the MN, similar to box 703. In response, the S-SN receives a third SN confirmation message from the MN, including a third LTM candidate configuration for the third cell used for LTM, similar to box 709A. The S-SN assigns a third configuration ID to identify the third LTM candidate configuration, similar to box 762. In one implementation, the S-SN includes the third LTM candidate configuration and the third configuration ID in a first RRC message or a second RRC message. In another implementation, the S-SN sends a third RRC message to the UE including the third LTM candidate configuration and the third configuration ID, similar to box 718. In some implementations, the third SN request message includes the third cell ID of the third cell. In some implementations, the third SN confirmation message includes the third cell ID in response to a third SN request including the third cell ID.

[0212] When the S-SN prepares the first cell, the second cell, and / or the third cell simultaneously as described above, the S-SN can determine which SN confirmation message responds to which SN request message based on the cell ID in the SN request message and the SN confirmation message.

[0213] In some implementations, the configuration ID described above and below includes or includes, as in the references Figures 3 to 5 The LTM ID described.

[0214] Figure 7B This is a flowchart of an example method 700B, similar to method 700A, except that method 700B includes block 709B instead of blocks 709A and 762. At block 709B, the S-SN receives an SN confirmation message from the MN, including a first LTM candidate configuration and a first configuration ID, where the first LTM candidate configuration is configured for the first cell in LTM. Unlike method 700A, in method 700B, the S-SN does not assign a configuration ID to the first LTM candidate configuration. In some implementations, the MN assigns a first configuration ID, a second configuration ID, and / or a third configuration ID. In other implementations, the C-SN assigns the first configuration ID, the second configuration ID, and / or the third configuration ID. In one implementation, the MN receives the first configuration ID, the second configuration ID, and / or the third configuration ID from the C-SN in a first SN request confirmation message, a second SN request confirmation message, and / or a third SN request confirmation message, respectively.

[0215] Figure 7CThis is a flowchart of example method 700C, similar to methods 700A and 700B, except that method 700C includes block 709C instead of blocks 709A, 762, and 718. At block 709C, the S-SN receives from the MN a first configuration ID associated with the first cell ID of the first cell, but not including the LTM candidate configuration. Unlike methods 700A and 700B, the SN confirmation message does not include the LTM candidate configuration because the MN sends the LTM candidate configuration for the first cell, not the S-SN.

[0216] Figure 8A This shows that it can be generated by S-SN (e.g., Figures 6A to 6D Example method 800A is similar to method 700A, implemented by the CU of S-SN 104A. Method 800A begins at block 802, where the CU communicates with the UE located in the DC along with the MN and S-SN, and the CU communicates with the UE via S-DU. At block 880-1, the CU may perform CU-DU-internal LTM configuration and / or execution procedures with the S-DU and the UE (e.g., events 396 or 380). At block 880-2, the CU may perform CU-DU-internal LTM configuration and / or execution procedures with the C-DU and the UE (e.g., events 496 or 480). The process proceeds to blocks 760, 703, 709A, and 762. At block 812, the CU sends a first CU-DU message to the S-DU including a first configuration ID and a first cell ID of the first cell. At block 818, the CU sends a first RRC message to the UE via the S-DU or MN including a first LTM candidate configuration and a first configuration ID. At frame 828, the CU receives from the S-DU. DU-CU cell handover notification The DU-CU cell handover notification message informs the CU that the S-DU is initiating an LTM cell handover command to UE 102 for an LTM cell handover to the first cell. The process can proceed to blocks 727, 731, and / or 741.

[0217] against Figure 7A The examples and implementations described can be applied to Figure 8A In some implementations, the CU includes the second configuration ID and the second cell ID in the first CU-DU message. In other implementations, the CU sends a second CU-DU message to the S-DU including the second configuration ID and the second cell ID, similar to events 312, 392, or 492. In some implementations, the CU includes the third configuration ID and the third cell ID in either the first or second CU-DU message. In other implementations, the CU sends a third CU-DU message to the S-DU including the third configuration ID and the third cell ID, similar to events 312, 392, or 492.

[0218] Figure 8B This is a flowchart of an example method 800B, similar to methods 800A and 700B, except that method 800B includes boxes 709B or 709C instead of boxes 709A and 762.

[0219] Figure 9A It shows that it can be made by MN (e.g., Figures 6A to 6D Example method 900A is implemented by MN (104B). Method 900A begins at block 902, where the MN communicates with a UE located in the same DC as the MN and the S-SN. At block 980, the MN may perform at least one in-MN LTM configuration and / or execution procedure with the UE (e.g., events 396, 380, 496, and / or 480). At block 905, the MN sends an SN request message to the C-SN to request the preparation of a first cell as an LTM candidate cell for the UE. At block 907A, the MN receives from the C-SN an SN request confirmation message including a first LTM candidate configuration for configuring the first cell as an LTM candidate cell for the UE. At block 962, the MN assigns a first configuration ID (e.g., a configuration identifier) ​​to identify the first LTM candidate configuration. At block 918, the MN sends a first RRC message to the UE including the first LTM candidate configuration and the first configuration ID. At block 926, the MN may send an LTM cell handover command to the UE, which instructs the UE to perform an LTM cell handover to the first cell. At box 927, MN can send CU to CU to S-SN. Cell handover notification The CU-to-CU cell handover notification message notifies the MN to initiate the transmission of an LTM cell handover command to the UE for an LTM cell handover to the first cell. At block 928, the MN can send the CU-to-CU message to the C-SN. Cell handover notification The CU-to-CU cell handover notification message notifies the MN to transmit an LTM cell handover command to the UE for an LTM cell handover to the first cell. At block 931, the MN can receive this message from the S-SN. Early status transmission Delivery The early state delivery message includes the DL COUNT value or DISCARD DL COUNT value of the DRB for data communication between UE 102 and S-SN. At block 933, MN can send the DL COUNT value or DISCARD DL COUNT value to C-SN. Early state transfer Message. At box 939, the MN can receive an LTM success message from the C-SN. At box 942, the MN can send the UL COUNT value, including the DRB, and / or the DL COUNT value to the C-SN. SN status transmission information.

[0220] In some implementations of box 918, the MN generates a first LTM configuration including a first LTM candidate configuration and a first configuration ID, and the MN includes the first LTM configuration in a first RRC message. In some implementations, the SN request message includes a first cell ID of the first cell, and the SN request confirmation message includes the first cell ID in response to the SN request message including the first cell ID.

[0221] In some implementations, when or after preparing the first cell for LTM, the MN can prepare a second cell of the C-SN (i.e., the first C-SN) as an LTM candidate cell for the UE by sending a second SN request message to the C-SN, similar to box 905. In response, the MN receives a second SN request confirmation message from the C-SN, which includes a second LTM candidate configuration for the second cell used for LTM, similar to box 907A. The MN assigns a second configuration ID to identify the second LTM candidate configuration, similar to box 962. In one implementation, the MN includes the second LTM candidate configuration and the second configuration ID in a first RRC message. In another implementation, the MN sends a second RRC message to the UE, which includes the second LTM candidate configuration and the second configuration ID, similar to box 918. In some implementations, the second SN request message includes a second cell ID of the second cell, and the second SN request confirmation message includes the second cell ID in response to the second SN request including the second cell ID.

[0222] In some implementations, when or after preparing the first cell for LTM, the MN can prepare a third cell of another C-SN (i.e., the second C-SN) as an LTM candidate cell for the UE by sending a third SN request message to the second C-SN, similar to box 905. In response, the MN receives a third SN request confirmation message from the second C-SN, including a third LTM candidate configuration for the third cell used for LTM, similar to box 907A. The MN assigns a third configuration ID to identify the third LTM candidate configuration, similar to box 962. In one implementation, the MN includes the third LTM candidate configuration, and the MN includes the third configuration ID in either the first or second RRC message. In another implementation, the MN sends a third RRC message to the UE including the third LTM candidate configuration and the third configuration ID, similar to box 918. In some implementations, the third SN request message includes the third cell ID of the third cell, and the third SN request confirmation message includes the third cell ID in response to the third SN request including the third cell ID.

[0223] When the MN prepares the first cell, the second cell, and / or the third cell simultaneously as described above, the MN can determine which SN request confirmation message responds to which SN request message based on the cell ID in the SN request message and the SN request confirmation message.

[0224] Figure 9B This is a flowchart of an example method 900B, similar to method 900A, except that method 900B includes block 907B instead of blocks 907A and 962. At block 907B, the MN receives an SN request confirmation message from the C-SN, including a first LTM candidate configuration and a first configuration ID, where the first LTM candidate configuration is configured for the first cell in LTM. Unlike method 900A, in method 900B, the C-SN assigns a configuration ID to the first LTM candidate configuration.

[0225] Figure 10A It shows that it can be made by MN (e.g., Figures 6A to 6D Example method 1000A is similar to method 900A, implemented by the CU of MN 104B. Method 1000A begins at block 1002, where the CU communicates with the UE located in the DC of the same MN and S-SN, wherein the CU communicates with the UE via S-DU. At block 1080-1, the CU may perform CU-DU-LTM configuration and / or execution procedures with the S-DU and the UE (e.g., events 396, 380, 696, or 680). At block 1080-2, the CU may perform CU-DU-LTM configuration and / or execution procedures with the C-DU and the UE (e.g., events 496, 480, 696, or 680). The process proceeds to blocks 905, 907A, and 962. At block 1012, the CU sends a CU-DU message to the S-DU including a first configuration ID and a first cell ID of the first cell. At box 1018, the CU sends a first RRC message to the UE via the S-DU, including a first LTM candidate configuration and a first configuration ID. The procedure can proceed to boxes 927, 928, 931, 933, 939 and / or 942.

[0226] against Figure 9A The examples and implementations described can be applied to Figure 10A .

[0227] Figure 10B This is a flowchart of example method 1000B, which is similar to methods 1000A and 900B, except that method 1000B includes box 907B instead of boxes 907A and 962.

[0228] Figure 11 It shows that it can be generated by C-SN (e.g., Figures 6A to 6DExample method 1100 is implemented using C-SN 106A. Method 1100 begins at block 1105, where the C-SN receives an SN request message from the MN requesting the preparation of a first cell as an LTM candidate cell for the UE. At block 1107, the C-SN sends an SN request confirmation message to the MN including a first LTM candidate configuration for the first cell used for LTM. At block 1128, the C-SN can receive CU from the MN to the CU Cell handover notification The CU-to-CU cell handover notification message notifies the transmission of an LTM cell handover command to the UE for an LTM cell handover to the first cell. At block 1133, the C-SN can receive from the MN the DL COUNT value or DISCARD DL COUNT value, which includes the DRB configured for UE 102. Early state transfer In box 1132, the C-SN can detect that the UE has accessed the first cell. In box 1139, the C-SN can send an LTM success message to the MN, which notifies the UE that it has successfully accessed the first cell. In box 1142, the C-SN can receive from the MN the UL COUNT value including the DRB and / or the DL COUNT value. SN status transmission Message. At box 1140, the C-SN can communicate with the UE via the first cell.

[0229] In some implementations, the C-SN can prepare a second cell for the UE as an LTM candidate cell, as described above.

[0230] Figure 12 It shows that it can be generated by C-SN (e.g., Figures 6A to 6D Example method 1200 is implemented by the CU (C-SN 106A). Method 1200 begins at block 1205 performed by the CU. At block 1208, the CU sends a CU-DU message including an LTM indicator to the DU. At block 1210, the CU receives a DU-CU message including a first LTM DU configuration from the DU. At block 1211, the CU generates a first LTM candidate configuration including the first LTM DU configuration. The process proceeds to block 1207, and may then proceed to blocks 1128, 1133, 1234, 1139, 1142, and / or 1140. At block 1234, the CU receives an access success message from the DU, which indicates that the UE accesses the first cell. At block 1240, the CU communicates with the UE via the DU and the first cell.

[0231] In some implementations, when preparing a second cell as described above, the CU performs actions similar to those described for boxes 1208, 1210, and 1211 to generate a second LTM candidate configuration.

[0232] against Figures 7A to 10BThe examples and implementations described can be applied to Figure 11 and Figure 12 .

[0233] Figure 13 It shows that it can be generated by SN (e.g., Figures 6A to 6D Example method 1300 is implemented by the CU of C-SN 106A. Method 1300 begins at box 1305, where the CU receives an SN request message from the MN. At box 1364, the CU determines whether the SN request message requests a cell to be prepared for LTM. If the SN request message requests a cell to be prepared for LTM (i.e., the "Yes" branch of box 1364), the process proceeds to box 1308. At box 1308, the CU sends a CU-DU message including an LTM indicator to the DU. Otherwise, if the SN request message does not request a cell to be prepared for LTM (i.e., the "No" branch of box 1364) (e.g., the SN request message requests a cell not to be prepared for LTM), the process proceeds to box 1309. At box 1309, the CU sends a CU-DU message excluding the LTM indicator to the DU. At box 1310, the CU receives a DU-CU message including the DU configuration from the DU. The process proceeds from box 1309 and box 1308 to box 1310. At box 1311, the CU generates an RRC reconfiguration message that includes the DU configuration. At box 1307, the CU sends an SN acknowledgment message that includes the RRC reconfiguration message to the MN.

[0234] In some implementations, the CU-DU message in block 1308 is a UE context establishment request message, and the CU receives a UE context establishment response message from the DU in response to the UE context establishment request message. In other implementations, the CU-DU message in block 1308 is a UE context modification request message, and the CU receives a UE context modification response message from the DU in response to the UE context establishment request message. In some implementations, the CU-DU message in block 1309 is a UE context establishment request message, and the CU receives a UE context establishment response message from the DU in response to the UE context establishment request message. In some implementations, the SN request message includes the cell ID of the cell, and the CU includes the cell ID in the CU-DU message. In some implementations, the DU configuration is an LTM DU configuration. In one implementation, the LTM DU configuration is an incremental configuration based on the LTM reference DU configuration. In another implementation, the LTM DU is a complete configuration.

[0235] In some implementations, the LTM indicator (e.g., the first LTM indicator) is a CU-DU interface protocol (e.g., F1AP) field / IE. In some implementations, if the SN request message includes the second LTM indicator, the CU determines that the SN request message requests a cell to be prepared for LTM, and includes the first LTM indicator in the CU-DU message at box 1308. Otherwise, if the SN request message does not include or excludes the second LTM indicator, the CU determines that the SN request message requests a cell not to be prepared for LTM, and does not include the first LTM indicator in the CU-DU message or excludes the first LTM indicator at box 1309.

[0236] Figure 14 This shows that it can be generated by S-SN (e.g., Figures 6A to 6D Example method 1400 is implemented using S-SN 104A. Method 1400 begins at box 1403, where the S-SN sends an SN request message to the MN. At box 1409, the S-SN receives an SN confirmation message from the MN that includes a first RRC reconfiguration message. At box 1464, the S-SN determines whether the SN request message requests a cell to be prepared for LTM. If the SN changes the request message to request a cell to be prepared for LTM (i.e., the "yes" branch of box 1464), the process proceeds to box 1465. At box 1465, the S-SN generates an LTM configuration, where the LTM configuration includes the first RRC reconfiguration message. At box 1466, the S-SN includes the LTM configuration in a second RRC reconfiguration message. At box 1467, the S-SN includes the second RRC reconfiguration message in a DL-DCCH-Message message.

[0237] Otherwise, if the SN requests that the message not request preparation of a cell for LTM (i.e., the "No" branch of box 1464) (e.g., the SN requests that the message request preparation of a cell not used for LTM), the process proceeds to box 1468. At box 1468, the S-SN includes the first RRC reconfiguration message in... DL-DCCH-Message In the message, at box 1418, the S-SN sends a message to the UE or MN. DL- DCCH-Message Message. The process proceeds from boxes 1468 and 1467 to box 1418.

[0238] Figure 15 This shows that it can be generated by S-SN (e.g., Figures 6A to 6DExample method 1500 is implemented using S-SN 104A. Method 1500 begins at box 1570, where the S-SN initiates an SN procedure (e.g., an SN change procedure or an SN modification procedure) to prepare the cell for the UE. At box 1572, the S-SN includes the cell ID of the cell in the SN request message of the SN procedure. At box 1563, the S-SN determines whether to initiate an SN procedure for LTM. If an SN procedure is initiated for LTM (i.e., the "Yes" branch of box 1563), the process proceeds to boxes 1574 and 1503. At box 1574, the S-SN includes the LTM indicator in the SN request message. Otherwise, if an SN procedure is initiated for LTM (i.e., the "No" branch of box 1563), the process skips box 1574 and proceeds to box 1503. At box 1503, the S-SN sends an SN request message to the MN.

[0239] Figure 16 It shows that it can be made by MN (e.g., Figures 6A to 6D Example method 1600 is implemented by MN 104B. Method 1600 begins at box 1605, where the MN sends an SN request message to the SN. For example, the SN can be a C-SN (e.g., C-SN106A). In another example, the SN can be an S-SN (e.g., S-SN 104A). At box 1607, the MN receives an SN request acknowledgment message from the SN, which includes a first RRC reconfiguration message. At box 1664, the MN determines whether the SN request message requests a cell to be prepared for LTM. If the SN request message requests a cell to be prepared for LTM (i.e., the "yes" branch of box 1664), the process proceeds to box 1665. At box 1665, the MN generates an LTM configuration, which includes the first RRC reconfiguration message. At box 1666, the MN includes the LTM configuration in a second RRC reconfiguration message. At box 1667, the MN includes the second RRC reconfiguration message in... DL-DCCH-Message In the message. Otherwise, if the SN request message does not request a cell to be prepared for LTM (i.e., the "No" branch of box 1664) (e.g., the SN request message does not request a cell to be prepared for LTM), the process proceeds to box 1668. At box 1668, the MN includes the first RRC reconfiguration message. DL-DCCH-Message In the message, at box 1618, the MN sends a message to the UE. DL-DCCH-Message Message. The process proceeds from boxes 1668 and 1667 to box 1618.

[0240] Figure 17 It shows that it can be made by MN (e.g., Figures 6A to 6DExample method 1700 is implemented by MN 104B. Method 1700 begins at box 1770, where MN initiates an SN addition procedure for the UE. At box 1772, MN includes the cell ID of the cell in the SN request message. At box 1763, MN determines whether to initiate an SN addition procedure for LTM. If an SN addition procedure is initiated for LTM, the procedure proceeds to box 1774. At box 1774, MN includes the LTM indicator in the SN request message. Otherwise, if no SN addition procedure is initiated for LTM, the procedure skips box 1774 and proceeds to box 1705. In other words, if no SN addition procedure is initiated for LTM, MN avoids including the LTM indicator in the SN request message. At box 1705, MN sends an SN request message to the second BS. The procedure proceeds from box 1774 and box 1763 to box 1705.

[0241] Figure 18 An example method 1800, which can be implemented by an SN (e.g., S-SN 104A, C-SN 106A, or CU 172), is shown. Method 1800 begins at box 1805, where the SN receives an SN request message from an MN requesting preparation of a cell for the UE. At box 1876, the SN obtains the RRC configuration for the UE to communicate on the cell. At box 1864, the SN determines whether the SN request message requested preparation of a cell for LTM. If the SN request message requests preparation of a cell for LTM (i.e., the "Yes" branch of box 1864), the process proceeds to box 1882. At box 1882, the SN includes the RRC configuration in a first field / IE of the SN request confirmation message. Otherwise, if the SN request message does not request preparation of a cell for LTM (i.e., the "No" branch of box 1864), the process proceeds to box 1884. At box 1884, the SN includes the RRC configuration in a second field / IE of the SN request confirmation message. The process proceeds from boxes 1882 and 1884 to box 1807. At box 1807, the SN sends an SN request confirmation message to the MN.

[0242] In some implementations, the first BS generates an RRC reconfiguration message that includes RRC configuration. The first BS includes the RRC reconfiguration message in the first field / UE at box 1882 or in the second field / IE at box 1884, as described above. In some implementations, the RRC reconfiguration includes physical layer configuration parameters, MAC configuration parameters and / or RLC configuration parameters, PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters.

[0243] In some implementations, the CU of the SN receives the DU configuration from the DU of the SN (e.g., CellGroupConfig(IE), wherein the DU configuration includes at least a portion of the RRC configuration. The CU includes the DU configuration in the RRC reconfiguration message, and the CU includes the RRC reconfiguration message in the first field / UE at box 1882 or in the second field / IE at box 1884, as described above.

[0244] The following descriptions can be applied to the descriptions above.

[0245] In some implementations, the SN requirement message and the SN confirmation message are respectively SN changed requirements Messages and SN changes confirmed certificate Message. In other implementations, the SN requirement message and the SN confirmation message are respectively SN Modification Requirements Messages and SN modification confirmed certificate Messages. In some implementations, the SN request message and the SN request acknowledgment message are respectively... SN Add Request Messages and SN Add Add confirmation request Messages. In other implementations, the SN request message and the SN request confirmation message are respectively SN Modification Request Messages and SN modification request confirmation information.

[0246] Figure 19 It can be in MN (e.g., MN 104B) Figure 6A The flowchart of the example method 1900 for LTM between CUs under DC is implemented in )).

[0247] Method 1900 begins at box 1905, at which point the MN sends a request to the candidate secondary node (C-SN) for candidate cells associated with the C-SN that are ready for low-layer triggered mobility (LTM) (e.g., events 605, 698A, 698B, 905, or 1605).

[0248] Method 1900 continues at block 1907, where MN receives from C-SN and in response to the request a message including LTM configuration for the candidate cell (e.g., events 607, 698A, 698B, 907A, 907B, or 1607).

[0249] Method 1900 continues at block 1918, whereby the MN provides the LTM configuration to the UE (e.g., events 694A, 318, 609A, 609B, 694C, 918, 1018, or 1618). Providing the LTM configuration may include sending an RRC message including the LTM configuration (e.g., events 918, 1018, or 1618). Providing the LTM configuration to the UE may also include sending the LTM configuration to the S-SN (e.g., events 609A, 609B, 698A, or 698B).

[0250] Method 1900 may include assigning a configuration identifier (ID) to the LTM configuration and sending the configuration ID to the UE (e.g., event 907A, 907B, or 918). Method 1900 may include receiving a configuration ID corresponding to the LTM configuration in a message that includes the LTM configuration; and sending the configuration ID to the UE (e.g., event 907B or 918).

[0251] Method 1900 can be implemented in the CU of the MN, and method 1900 may further include sending a CU-DU message including a configuration ID to the distributed unit (DU) of the MN (e.g., event 1012). Method 1900 may further include receiving a timing advance (TA) value for the candidate cell from the C-SN; and sending the TA value to the S-SN (e.g., event 657 or 658).

[0252] Method 1900 may further include sending a command to the UE for initiating an LTM handover to a candidate cell. Method 1900 may further include sending a CU-to-CU cell handover notification message to the C-SN (e.g., event 628 or 928). Method 1900 may further include receiving a first CU-to-CU cell handover notification message from the S-SN when the CU-to-CU cell handover notification message is a second CU-to-CU cell handover notification message, wherein the transmission of the second CU-to-CU cell handover notification message is in response to the reception of the first CU-to-CU cell handover notification message (e.g., event 627A).

[0253] Figure 20 This is a flowchart of example method 2000 that can be implemented in candidate SN.

[0254] Method 2000 begins at block 2005, where the C-SN receives from the primary node (MN) a request for candidate cells associated with the C-SN to be prepared for low-layer triggered mobility (LTM), the MN communicating with the source secondary node (S-SN) under dual connectivity (DC) with the user equipment (UE) (e.g., events 605, 698A, 698B, 1205, or 1305).

[0255] Method 2000 continues at block 2007, wherein the C-SN sends a message (e.g., event 607, 698A, 698B, or 1107) to the MN and in response to the request, including the LTM configuration for the candidate cell.

[0256] Method 2000 may include operations implemented in the CU of the C-SN. These operations may include sending a CU-DU message including an LTM indicator to the DU of the C-SN to request DU configuration (e.g., event 1308 or 1310). Method 2000 may also include using the DU configuration to generate a Radio Resource Control (RRC) reconfiguration message. Method 2000 may also include sending an RRC reconfiguration message to the MN (e.g., event 1311 or 1307). Method 2000 may also include assigning a configuration identifier (ID) to the LTM configuration and sending the configuration ID along with the LTM configuration to the MN (e.g., event 907B or 918). Method 2000 may include sending a timing advance (TA) value for candidate cells to the MN (e.g., event 657 or 658).

[0257] The following list of examples reflects various embodiments explicitly contemplated in this disclosure.

[0258] Example 1. A method implemented in a primary node (MN) that provides dual connectivity (DC) to a user equipment (UE) with a source secondary node (S-SN), the method comprising: receiving a low-layer triggered mobility (LTM) configuration from a candidate SN (C-SN), the LTM configuration including LTM configuration information of candidate cells associated with the C-SN; and sending to the UE a configuration identifier assigned by the MN corresponding to the LTM configuration.

[0259] Example 2. The method as described in Example 1, wherein: the sending includes generating a Radio Resource Control (RRC) message including the configuration identifier and the LTM configuration.

[0260] Example 3. The method as described in any of the preceding examples, wherein: the transmission includes transmitting a Physical Downlink Control Channel (PDCCH) command or an LTM cell handover command including the configuration identifier.

[0261] Example 4. The method as described in any of the preceding examples, wherein the configuration identifier is included in a field having an integer format.

[0262] Example 5. The method as described in any of the preceding examples, wherein the configuration identifier is included in a field having a binary format.

[0263] Example 6. The method as described in any of the preceding examples, wherein the field comprises three bits.

[0264] Example 7. The method as described in any of the preceding examples further includes: sending a request for LTM configuration to the C-SN.

[0265] Example 8. The method as described in Example 7, wherein the request for LTM configuration is included in the SN request message.

[0266] Example 9. The method as described in Example 7 further includes: sending a second request for a second candidate cell configured for LTM.

[0267] Example 10. The method as described in Example 9, wherein the second request is sent to a second SN different from the C-SN.

[0268] Example 11. The method as described in any of the preceding examples, wherein the LTM configuration is received in an acknowledgment from the C-SN.

[0269] Example 12. The method as described in Example 11, wherein the confirmation includes the cell identifier of the candidate cell.

[0270] Example 13. The method as described in Example 11, wherein the C-SN assigns the configuration identifier to the LTM configuration, and the MN avoids assigning the configuration identifier to the LTM configuration.

[0271] Example 14. The method as described in any of the preceding examples further includes: receiving from a source SN (S-SN) a message identifying one or more of the candidate cells or the C-SN.

[0272] Example 15. The method as described in Example 14, wherein: the message identifying one or more of the candidate cells or the C-SNs includes an SN request message.

[0273] Example 16. The method as described in Example 15, wherein: the SN request message includes an identification of the source distributed unit (S-DU) or a base station identifier.

[0274] Example 17. The method of Example 14 further includes: receiving an early status delivery notification from the S-SN, the notification including parameters for downlink communication; and sending an early status delivery message received from the source SN and including parameters for downlink communication to the C-SN.

[0275] Example 18. The method as described in Example 17 further includes: sending an acknowledgment including the LTM configuration to the source SN.

[0276] Example 19. The method as described in Example 18, wherein the confirmation includes early synchronization information.

[0277] Example 20. The method as described in Example 19, wherein the verification includes the configuration identifier.

[0278] Example 21. The method as described in Example 18, wherein the verification includes an SN modification request.

[0279] Example 22. The method as described in any of the preceding examples further includes sending the configuration identifier to the distributed unit associated with the C-SN.

[0280] Example 23. The method as described in any of the preceding examples, wherein the configuration identifier is associated with at least one of a cell identifier, an LTM DU configuration, and a Channel State Indicator (CSI) report configuration.

[0281] Example 24. The method as described in any of the preceding examples, wherein the MN is a distributed base station comprising a central unit (CU) and at least one distributed unit (DU).

[0282] Example 25. The method as described in any of the preceding examples, wherein the SN is a distributed base station comprising a central unit (CU) and at least one distributed unit (DU).

[0283] Example 26. A method implemented in a secondary node (SN) that provides dual connectivity to a user equipment (UE) along with a primary node (MN), the method comprising: receiving from the MN an LTM configuration for a low-layer triggered mobility (LTM) candidate secondary cell; and sending to the UE a configuration identifier assigned by the SN corresponding to the LTM configuration.

[0284] Example 27. The method as described in Example 26, wherein the LTM configuration is received from the MN in a confirmation message.

[0285] Example 28. The method as described in Example 27, wherein: the confirmation message includes an SN change confirmation message.

[0286] Example 29. The method as described in Example 28, wherein: the SN change confirmation message includes an SN modification request message.

[0287] Example 30. The method of any one of Examples 27 to 29, wherein: the confirmation message includes channel state information (CSI) resource configuration information.

[0288] Example 31. The method as described in any one of Examples 27 to 30, wherein: the confirmation message includes LTM synchronization signal block (SSB) configuration information.

[0289] Example 32. The method of any one of Examples 27 to 31, wherein: the confirmation message includes the physical cell ID (PCI) of the LTM candidate secondary cell.

[0290] Example 33. The method as described in any one of Examples 27 to 32, wherein the confirmation message includes early synchronization information.

[0291] Example 34. The method as described in any one of Examples 27 to 33, wherein: the confirmation message includes an identifier for identifying a candidate LTM configuration among a plurality of LTM configurations.

[0292] Example 35. The method of any one of Examples 26 to 34 further includes: in response to receiving a measurement report from the UE, sending a message to the MN identifying the LTM candidate secondary cell or a candidate SN associated with the LTM candidate secondary cell.

[0293] Example 36. The method as described in Example 35, wherein: the message identifying the LTM candidate secondary cell or the candidate SN associated with the LTM candidate secondary cell includes an SN request message.

[0294] Example 37. The method as described in Example 36, wherein: the message identifying one or more of the LTM candidate secondary cells or the candidate SNs includes an LTM indicator indicating that the message is associated with LTM for the LTM candidate secondary cell.

[0295] Example 38. The method as described in Example 37, wherein: the SN request message includes an identification of the source distributed unit (S-DU) or a base station identifier.

[0296] Example 39. The method as described in any one of Examples 26 to 38, wherein the configuration identifier is included in a field having an integer format.

[0297] Example 40. The method as described in any one of Examples 26 to 38, wherein the configuration identifier is included in a field having a binary format.

[0298] Example 41. The method as described in Example 40, wherein the field comprises three bits.

[0299] Example 42. The method of any one of Examples 26 to 41, further comprising: sending an early state delivery notification to the MN, the notification including parameters for downlink communication.

[0300] Example 43. The method of any one of Examples 26 to 42 further includes sending a notification message to the MN to indicate that the UE has completed LTM cell handover.

[0301] Example 44. The method of any one of Examples 26 to 43, wherein the SN is a distributed base station comprising a central unit (CU) and at least one distributed unit (DU). Generally, a description for one of the above figures may be applied to another of the above figures. The examples, implementations, and methods described above may be combined if there is no conflict. Events or boxes described above may be optional or omitted. For example, events or boxes with dashed lines in the figures may be optional. Descriptions from the perspective of the receiving node also apply to the sending node. For example, a description of a receiving node (e.g., DU) receiving a message from a sending node (e.g., CU) can be used instead of a description of a receiving node (e.g., CU) receiving a message from a sending node (e.g., DU). Similarly, a description of a receiving node (e.g., CU) receiving a message from a sending node (e.g., DU) can be used instead of a description of a sending node (e.g., CU) receiving a message from a sending node (e.g., DU).

[0302] In some implementations, "message" is used, and "information element (IE)" can be used instead of "message," and vice versa. In some implementations, "IE" is used, and "field" can be used instead of "IE," and vice versa. In some implementations, "configurations" or "configuration parameters" can be used instead of "configuration," and vice versa. In some implementations, "serving cell change command," "Layer 1 / Layer 2 LTM cell handover command," "lower layer handover command," or "lower layer serving cell change command" can be used instead of "LTM command." In some implementations, "some" means "one or more." In some implementations, "at least one" means "one or more." In some implementations, "cell group configuration" can be used instead of "DU configuration." In some implementations, "serving cell index," "LTM cell index," "special cell (SpCell) index," "PCell index," or "PSCell index" can be used instead of "cell index." In some implementations, "source" can be used instead of "service." In some implementations, "measurement result" or "CSI report" can be used instead of "measurement report". In some implementations, "early UL timing synchronization" or "early UL synchronization" can be used instead of "early TA acquisition". In some implementations, "with candidate cell / early UL timing synchronization with the candidate cell" or "with candidate cell / early UL synchronization with the candidate cell" can be used instead of "early TA acquisition on candidate cell / the candidate cell". In some implementations, "comprise" can be used instead of "include". In some implementations, "avoid including" can be used instead of "exclude". In some implementations, the above-described " Transfer Request "and" Transfer request confirmed recognize"This is for illustrative purposes and can be replaced by messages with generic names. For example, it can be replaced by a first CU to CU message and a second CU to CU message, respectively." Transfer Request "and" Confirmation of transfer request In another example, "" can be replaced by the first interface message and the second interface message respectively. Transfer Request "and" Confirmation of transfer request In yet another example, "" can be replaced by the first BS to BS message and the second BS to BS message, respectively. Transfer Request "and" Confirmation of transfer request In some implementations, the terms "SN request," "SN confirmation," "SN request," and "SN request confirmation" described above are for illustrative purposes and can be replaced by messages with generic names. For example, an SN to MN message can be used instead of an "SN request message." In another example, an MN to SN message can be used instead of an "SN confirmation message."

[0303] The user device (e.g., UE 102) in which the technology of this disclosure operates 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.

[0304] 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.

[0305] 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.

[0306] Upon reading this disclosure, those skilled in the art will understand the additional and alternative structural and functional designs used to address mobility between base stations through the principles disclosed herein. Therefore, while specific embodiments and applications have been shown and described, 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 method implemented in a master node (MN), wherein the MN and a source secondary node (S-SN) communicate in dual connectivity (DC) with a user equipment (UE), the method comprising: Send a request to the candidate secondary node (C-SN) for candidate cells associated with the C-SN that are ready for low-layer triggered mobility (LTM); Receive a message from the C-SN and in response to the request, including the LTM configuration for the candidate cell; as well as Provide the LTM configuration to the UE.

2. The method of claim 1, further comprising: Assign a configuration identifier (ID) to the LTM configuration; as well as Send the configuration ID to the UE.

3. The method of claim 1, further comprising: Receive a configuration ID corresponding to the LTM configuration in the message that includes the LTM configuration; as well as Send the configuration ID to the UE.

4. The method of claim 2 or 3, wherein the method is implemented in the central unit (CU) of the MN, and the method further comprises: Send a CU-DU message including the configuration ID to the distributed unit (DU) of the MN.

5. The method according to any of the preceding claims, further comprising: Receive timing advance (TA) values ​​for the candidate cells from the C-SN; as well as Send the TA value to the S-SN.

6. The method as described in any of the preceding claims, wherein providing the LTM configuration to the UE comprises: Send a Radio Resource Control (RRC) message that includes the LTM configuration.

7. The method as claimed in any of the preceding claims, wherein providing the LTM configuration to the UE comprises: Send the LTM configuration to the S-SN.

8. The method as described in any one of the preceding claims, further comprising: Send a command to the UE to initiate an LTM handover to the candidate cell; as well as Send a CU-to-CU cell handover notification message to the C-SN.

9. The method of claim 8, wherein: The CU-to-CU cell handover notification message is the second CU-to-CU cell handover notification message; The method further includes: The first CU-to-CU cell handover notification message is received from the S-SN, wherein sending the second CU-to-CU cell handover notification message is in response to receiving the first CU-to-CU cell handover notification message.

10. A method implemented in a candidate secondary node (C-SN), the method comprising: The MN receives a request from the primary node (MN) for candidate cells associated with the C-SN to be prepared for low-layer triggered mobility (LTM). The MN communicates with the source secondary node (S-SN) under dual connectivity (DC) with the user equipment (UE). as well as Send a message including the LTM configuration for the candidate cell to the MN in response to the request.

11. The method of claim 10, wherein the method is implemented in the central unit (CU) of the C-SN, the method further comprising: Send a CU-to-DU message including an LTM indicator to the distributed unit (DU) of the C-SN to request DU configuration.

12. The method of claim 11, further comprising: Use the DU configuration to generate a Radio Resource Control (RRC) reconfiguration message; as well as Send an RRC reconfiguration message to the MN.

13. The method of claim 10 or 11, further comprising: Assign a configuration identifier (ID) to the LTM configuration; as well as The configuration ID is sent to the MN along with the LTM configuration.

14. The method of any one of claims 10 to 13, further comprising: Send the timing advance (TA) value for the candidate cell to the MN.

15. A base station comprising a transceiver and processing hardware, the base station being configured to implement the method as described in any of the preceding claims.

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