inter-sn scgltm

Abstract

This disclosure includes exemplary embodiments of base stations, user equipment, methods, apparatuses, and computer-readable media for inter-SN SCG LTM. In this solution, a first base station (e.g., MN) sends a first request message to a second base station (e.g., a candidate T-SN), the first request message including a first indicator associated with the UE's SCG LTM. The second base station sends a first response message to the first base station, the first response message including an SCG LTM candidate configuration for each candidate PSCell. The first base station may provide the UE with an SCG LTM CSI resource configuration and an SCG LTM candidate configuration for each candidate PSCell. Therefore, the SCG LTM CSI resource configuration can be used for L1 measurement, and the SCG LTM candidate configuration can be used to connect to a target PSCell. Thus, inter-SN SCG LTM can be supported.

Description

Technical Field

[0001] This disclosure relates to wireless communications, and more particularly to radio access network (RAN) units, methods, apparatus, and computer-readable media for inter-SN secondary cell group (SCG) layer 1 / layer 2 triggered mobility (LTM). Background Technology

[0002] A wireless communication system may include one or more network communication devices, such as base stations, which may also be referred to as eNodeBs (eNBs), next-generation NodeBs (gNBs), or other suitable terms. Each network communication device (such as a base station) may support wireless communication for one or more user communication devices, which may also be referred to as user equipment (UEs), or other suitable terms. The wireless communication system may support wireless communication with one or more user communication devices by utilizing the resources of the wireless communication system (e.g., time resources (e.g., symbols, time slots, subframes, frames, etc.) or frequency resources (e.g., subcarriers, carriers)). Additionally, the wireless communication system may also support wireless communication across various radio access technologies, including third-generation (3G) radio access technology, fourth-generation (4G) radio access technology, fifth-generation (5G) radio access technology, and other suitable radio access technologies after 5G (e.g., sixth-generation (6G)).

[0003] When a UE moves from one cell to another, a serving cell change needs to be performed at some point. Traditionally, serving cell changes are performed via explicit radio resource configuration (RRC) reconfiguration signaling to trigger synchronization of the target cell based on Layer 3 (L3) measurement reports. This results in longer latency, greater overhead, and longer downtime compared to beam-level mobility.

[0004] Within the 3rd Generation Partnership Project (3GPP), a work item on further New Radio (NR) mobility enhancements (designated LTM) was approved to change the serving cell via Layer 1 / Layer 2 (L1 / L2) signaling in order to reduce latency, overhead, and downtime. LTM refers to a cell handover process triggered by a Media Access Control (MAC) control element (CE) based on L1 measurements, between the PCell (primary cell of the primary cell group) or the PSCell (primary cell of the secondary cell group). Summary of the Invention

[0005] This disclosure relates to base stations, user equipment, methods, apparatus, and computer-readable media for inter-SN SCG LTM. Enhancements for supporting SCG LTM are proposed based on the proposed solution.

[0006] In some implementations, a first base station is provided. The first base station includes at least one memory; and at least one processor, coupled to the at least one memory and configured such that the first base station: sends a first request message to a second base station, the first request message including a first indicator associated with the SCG LTM of a user equipment; receives a first response message from the second base station, the first response message including an SCG LTM candidate configuration for each of a plurality of candidate primary and secondary cells (PSCells) of the second base station; and sends to the user equipment the SCG LTM candidate configuration for each of the plurality of candidate PSCells and an SCG LTM Channel State Information (CSI) resource configuration, wherein the SCG LTM CSI resource configuration includes a plurality of reference signal (RS) configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate identifier (ID).

[0007] In some implementations, a second base station is provided. The second base station includes at least one memory; and at least one processor, the at least one processor being coupled to the at least one memory and configured such that the second base station: receives a first request message from a first base station, the first request message including a first indicator associated with a secondary SCG LTM of a user equipment; and sends a first response message to the first base station, the first response message including an SCG LTM candidate configuration for each of a plurality of candidate PSCells of the second base station.

[0008] In some implementations, a third base station is provided. The third base station includes at least one memory; and at least one processor coupled to the at least one memory and configured such that the third base station: receives a second modification request message from a first base station, the second modification request message including a third indicator associated with the SCG LTM of the user equipment; and sends a second modification response message to the first base station, the second modification response message including an SCG LTM CSI report configuration for the serving cell of the user equipment.

[0009] In some implementations, a user equipment is provided. The user equipment includes at least one memory; and at least one processor coupled to the at least one memory and configured such that the user equipment: receives from a first base station an SCG LTM candidate configuration for each of a plurality of candidate PSCells among one or more second base stations, and an SCG LTM CSI resource configuration, wherein the SCG LTM CSI resource configuration includes a plurality of RS configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate ID; receives from a third base station an SCG LTM cell handover command, the SCG LTM cell handover command including a target PSCell among the plurality of candidate PSCells, wherein the target PSCell is associated with a target base station among one or more second base stations; and, based on the SCG LTM cell handover command, hands over from the serving cell of the third base station to the target PSCell of the target base station.

[0010] In some implementations, a method is provided performed by a first base station. The method includes: sending a first request message to a second base station, the first request message including a first indicator associated with an SCG LTM of a user equipment; receiving a first response message from the second base station, the first response message including an SCG LTM candidate configuration for each of a plurality of candidate PSCells of the second base station; and sending to the user equipment the SCG LTM candidate configuration for each of the plurality of candidate PSCells, and an SCG LTM CSI resource configuration, wherein the SCG LTM CSI resource configuration includes a plurality of RS configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate ID.

[0011] In some implementations, a method is provided performed by a second base station. The method includes: receiving a first request message from a first base station, the first request message including a first indicator associated with an SCG LTM of a user equipment; and sending a first response message to the first base station, the first response message including an SCG LTM candidate configuration for each of a plurality of candidate PSCells of the second base station.

[0012] In some implementations, a method is provided performed by a third base station. The method includes: receiving a second modification request message from a first base station, the second modification request message including a third indicator associated with the SCG LTM of a user equipment; and sending a second modification response message to the first base station, the second modification response message including SCG LTM CSI report configuration for the serving cell of the user equipment.

[0013] In some implementations, a method performed by a UE is provided. The method includes: receiving from a first base station an SCG LTM candidate configuration for each of a plurality of candidate PSCells among one or more second base stations, and an SCG LTM CSI resource configuration, wherein the SCG LTM CSI resource configuration includes a plurality of RS configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate ID; receiving from a third base station an SCG LTM cell handover command, the SCG LTM cell handover command including a target PSCell among the plurality of candidate PSCells, wherein the target PSCell is associated with a target base station among one or more second base stations; and handing over from the serving cell of the third base station to the target PSCell of the target base station based on the SCG LTM cell handover command.

[0014] In some implementations, a processor for wireless communication is provided. The processor includes at least one controller coupled to at least one memory and configured to cause the processor to perform: sending a first request message to a second base station, the first request message including a first indicator associated with an SCG LTM of a user equipment; receiving a first response message from the second base station, the first response message including an SCG LTM candidate configuration for each of a plurality of candidate PSCells of the second base station; and sending to the user equipment the SCG LTM candidate configuration for each of the plurality of candidate PSCells and an SCG LTM CSI resource configuration, wherein the SCG LTM CSI resource configuration includes a plurality of RS configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate ID.

[0015] In some implementations, a processor for wireless communication is provided. The processor includes at least one controller coupled to at least one memory and configured to cause the processor to: receive a first request message from a first base station, the first request message including a first indicator associated with an SCG LTM of a user equipment; and send a first response message to the first base station, the first response message including an SCG LTM candidate configuration for each of a plurality of candidate PSCells of a second base station.

[0016] In some implementations, a processor for wireless communication is provided. The processor includes at least one controller coupled to at least one memory and configured to cause the processor to: receive a second modification request message from a first base station, the second modification request message including a third indicator associated with the SCG LTM of a user equipment; and send a second modification response message to the first base station, the second modification response message including SCG LTM CSI report configuration for the serving cell of the user equipment.

[0017] In some implementations, a processor for wireless communication is provided. The processor includes at least one controller coupled to at least one memory and configured to cause the processor to perform: receiving from a first base station an SCG LTM candidate configuration for each of a plurality of candidate PSCells among one or more second base stations, and an SCG LTM CSI resource configuration, wherein the SCG LTM CSI resource configuration includes a plurality of RS configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate ID; receiving from a third base station an SCG LTM cell handover command, the SCG LTM cell handover command including a target PSCell among the plurality of candidate PSCells, wherein the target PSCell is associated with a target base station among one or more second base stations; and handing over from the serving cell of the third base station to the target PSCell of the target base station based on the SCG LTM cell handover command.

[0018] In some implementations of the method described herein and the first base station, the method further includes: determining the SCG LTM CSI resource configuration, wherein the first request message further includes the SCG LTM CSI resource configuration.

[0019] In the methods described in this paper and some implementations of the first base station, the first response message also includes multiple RS configurations of multiple candidate PSCells, and further includes: determining the SCG LTM CSI resource configuration based on the first response message.

[0020] In some implementations of the method described herein and the first base station, the method further includes: sending a third request message to a third base station, the third request message including multiple RS configurations of multiple candidate PSCells and a third indicator associated with SCG LTM; and receiving a third response message from the third base station, the third response message including SCG LTM CSI resource configuration.

[0021] In some implementations of the method described herein and the first base station, the method further includes: receiving a second request message from a third base station, the second request message including a second indicator associated with SCG LTM; and sending a second response message to the third base station, the second response message indicating a plurality of candidate PSCells for SCG LTM.

[0022] In some implementations of the method described herein and the first base station, the method further includes: sending a first modification request message to a second base station, the first modification request message including a third indicator associated with SCG LTM; and receiving a first modification response message from the second base station, the first modification response message including SCG LTM CSI report configuration for each of the plurality of candidate PSCells.

[0023] In some implementations of the method described herein and the first base station, the method further includes: sending a second modification request message to a third base station, the second modification request message including a third indicator associated with SCG LTM; and receiving a second modification response message from the third base station, the second modification response message including SCG LTMCSI report configuration for the serving cell of the user equipment.

[0024] In some implementations of the method described herein and the first base station, the method further includes: receiving a desired message from a second base station, the desired message including a fourth indicator associated with SCG LTM and at least one candidate PSCell among a plurality of candidate PSCells, wherein at least one candidate PSCell among the plurality of candidate PSCells is associated with at least one of: an updated SCG LTM candidate configuration, or an updated SCG LTM CSI report configuration; and sending a desired response message to the second base station, the desired response message indicating acknowledgment of the desired message.

[0025] In some implementations of the method described herein and the first base station, the method further includes receiving a notification message from the third base station that includes the ID of the target PSCell among a plurality of candidate PSCells, wherein the notification message indicates that an SCG LTM cell handover command is initiated to the user equipment associated with the target PSCell.

[0026] In some implementations of the method described herein and the first base station, the method further includes receiving a reconfiguration completion message from the user equipment, including an LTM candidate ID, wherein the LTM candidate ID indicates an SCG LTM candidate configuration applied by the user equipment.

[0027] In some implementations of the method described herein and the first base station, the method further includes receiving a reconfiguration completion message from the user equipment, which includes a physical cell ID, wherein the physical cell ID indicates the target PSCell that the user equipment connects to after the SCG LTM cell handover.

[0028] In some implementations of the method and the second base station described herein, the method further includes: selecting multiple candidate PSCells from a list of suggested PSCells, wherein the first request message also includes the list of suggested PSCells.

[0029] In some implementations of the method and the second base station described herein, the method further includes: determining the SCG LTM reference configuration based on a first request message, wherein the first request message further includes a request for the SCG LTM reference configuration.

[0030] In some implementations of the method and the second base station described herein, the method further includes: receiving a first modification request message from a first base station, the first modification request message including a third indicator associated with SCG LTM; and sending a first modification response message to the first base station, the first modification response message including SCG LTM CSI report configuration for each of a plurality of candidate PSCells.

[0031] In some implementations of the method described herein and the second base station, the method further includes: sending a desired message to the first base station, the desired message including a fourth indicator associated with SCG LTM and at least one candidate PSCell among a plurality of candidate PSCells, wherein at least one candidate PSCell among the plurality of candidate PSCells is associated with at least one of: an updated SCG LTM candidate configuration, or an updated SCG LTM CSI report configuration; and receiving a desired response message from the first base station, the desired response message indicating acknowledgment of the desired message.

[0032] In some implementations of the method described herein and the third base station, the method further includes: sending a second request message to the first base station, the second request message including a second indicator associated with SCG LTM; and receiving a second response message from the first base station, the second response message indicating a plurality of candidate PSCells for SCG LTM.

[0033] In some implementations of the method described herein and the third base station, the method further includes: receiving a third request message from a first base station, the third request message including a third indicator associated with multiple RS configurations of the SCG LTM and multiple candidate PSCells; determining an SCG LTM CSI resource configuration based on the third request message, wherein the SCG LTM CSI resource configuration includes multiple RS configurations of the multiple candidate PSCells, and each of the multiple RS configurations is associated with an LTM candidate ID; and sending a third response message including the SCG LTM CSI resource configuration to the first base station.

[0034] In some implementations of the method described herein and the third base station, the method further includes: sending an SCGLTM cell handover command to the user equipment, the SCGLTM cell handover command including a target PSCell among multiple candidate PSCells; and sending a notification message including the ID of the target PSCell to the first base station, wherein the notification message indicates that an SCGLTM cell handover command is initiated to the user equipment.

[0035] In some implementations of the method and UE described herein, the method further includes sending a reconfiguration completion message including an LTM candidate ID to a first base station, wherein the LTM candidate ID indicates an SCG LTM candidate configuration applied by the user equipment.

[0036] In the methods described herein and some implementations of the UE, the method further includes sending a reconfiguration completion message including a physical cell ID to a first base station, wherein the physical cell ID indicates the target PSCell that the user equipment connects to after the SCG LTM cell handover.

[0037] In some implementations of the methods and base stations described in this paper, the third request message also includes an SCG LTM reference configuration.

[0038] In some implementations of the methods and base stations described herein, the third request message also includes a request for the SCG LTM reference configuration, and the third response message also includes the SCG LTM reference configuration.

[0039] In some implementations of the methods and base stations described herein, the second request message includes one of the following: a second indicator associated with SCG LTM, the ID of the second base station, a list of suggested PSCells, an SCG LTM reference configuration, or an SCG LTM CSI resource configuration.

[0040] In some implementations of the methods and base stations described herein, the first request message may also include one of the following: a list of suggested PSCells, an SCG LTM reference configuration, a request for an SCG LTM reference configuration, an SCG LTM CSI resource configuration, or a maximum number of candidate PSCells.

[0041] In some implementations of the methods and base stations described herein, the first response message may also include one of the following: multiple IDs of multiple PSCells, SCG LTM reference configuration, multiple RS configurations of multiple candidate PSCells, or SCG LTM CSI report configuration for each of the multiple candidate PSCells.

[0042] In some implementations of the methods and base stations described herein, the first modification request message may also include one of the following: a third indicator associated with SCG LTM, an SCG LTM CSI resource configuration, or an SCG LTM reference configuration.

[0043] In some implementations of the methods and base stations described herein, the first modified response message also includes an updated SCG LTM candidate configuration for each of the multiple candidate PSCells, and wherein the updated SCG LTM candidate configuration is based on the SCG LTM reference configuration.

[0044] In some implementations of the methods and base stations described herein, the second modification request message includes one of the following: a third indicator associated with SCG LTM, an SCG LTM CSI resource configuration, or a request for an SCG LTM reference configuration.

[0045] In some implementations of the methods and base stations described in this paper, the second modified response message also includes the SCG LTM reference configuration. Attached Figure Description

[0046] Figure 1 Examples of wireless communication systems in which some embodiments of this disclosure may be implemented are shown;

[0047] Figure 2A-2B The control plane architectures for Evolved Universal Terrestrial Radio Access New Radio Dual Connectivity (EN-DC) and Multiple Radio Dual Connectivity (MR-DC) with a fifth-generation core network (5GC) are shown respectively.

[0048] Figure 2C The radio protocol architecture for the Primary Cell Group (MCG), SCG, and separate bearers in an MR-DC with an evolved packet core (EPC) is shown from the UE's perspective.

[0049] Figure 2D The radio protocol architecture for MCG, SCG, and decoupled bearers in an MR-DC with 5GC is shown from the UE's perspective.

[0050] Figure 2E The network-side protocol termination options for MCG, SCG, and decoupled bearers in an MR-DC with EPC are shown.

[0051] Figure 2F The network-side protocol termination options for MCG, SCG, and decoupled bearers in an MR-DC with 5GC are shown.

[0052] Figure 2G The overall process for LTM is shown;

[0053] Figure 2H A schematic diagram of an example communication network in which some embodiments of the present disclosure may be implemented is shown;

[0054] Figure 3 Signaling diagrams of communication procedures for SCG LTM according to some example embodiments of the present disclosure are shown;

[0055] Figure 4 Signaling diagrams of communication procedures for SCG LTM according to some example embodiments of the present disclosure are shown;

[0056] Figure 5 Signaling diagrams of communication procedures for SCG LTM according to some example embodiments of the present disclosure are shown;

[0057] Figure 6 Examples of devices suitable for implementing embodiments of this disclosure are shown;

[0058] Figure 7 Examples of processors suitable for implementing some exemplary embodiments of this disclosure are shown;

[0059] Figure 8 A flowchart of an example method implemented at a first base station according to aspects of this disclosure is shown;

[0060] Figure 9 A flowchart of an example method implemented at a second base station according to aspects of this disclosure is shown;

[0061] Figure 10 A flowchart illustrating an example method implemented at a third base station according to aspects of this disclosure is shown; and

[0062] Figure 11 A flowchart of an example method implemented at the UE according to aspects of this disclosure is shown.

[0063] In all the accompanying drawings, the same or similar reference numerals denote the same or similar elements. Detailed Implementation

[0064] The principles of this disclosure will now be described with reference to some embodiments. It should be understood that these embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and implementing this disclosure, and do not imply any limitation on the scope of this disclosure. This disclosure described herein can be implemented in various ways other than those described below. In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0065] In this disclosure, references to "an embodiment," "example embodiment," "embodiment," "some embodiments," etc., indicate that the embodiments(s) described may include specific features, structures, or characteristics, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same(s) embodiments(s). Additionally, when a specific feature, structure, or characteristic is described in connection with an embodiment, those skilled in the art will recognize that, whether explicitly described or not, incorporating other embodiments to affect such a feature, structure, or characteristic is within their knowledge.

[0066] It should be understood that although the terms “first” and “second”, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms. In some examples, values, processes, or apparatus are referred to as “best,” “lowest,” “highest,” “minimum,” “maximum,” etc. It should be understood that such descriptions are intended to indicate that a choice among many functional alternatives is possible, and that such a choice need not be better, smaller, higher, or more preferred than other choices.

[0067] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the embodiments. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising,” “including,” “having,” “having,” “including,” and / or “containing” are used herein, they specify the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. For example, “comprising” and variations thereof should be understood as open-ended terms meaning “including, but not limited to.” The term “based on” should be understood as “at least partially based on.” The terms “one embodiment” and “embodiment” should be understood as “at least one embodiment.” The term “another embodiment” should be understood as “at least one other embodiment.” Expressions such as “A and / or B” can mean “A only,” “B only,” or “A and B.” Other explicit or implicit definitions may be listed below.

[0068] Figure 1 Examples of wireless communication systems 100 that may be implemented in accordance with some embodiments of this disclosure are shown. Wireless communication system 100 may include one or more network entities 102 (also referred to as network devices (NEs)), one or more UEs 104, a core network 106, and a packet data network 108. Wireless communication system 100 may support various radio access technologies. In some implementations, wireless communication system 100 may be a 4G network, such as a Long Term Evolution (LTE) network or an Advanced LTE (LTE-A) network. In some other implementations, wireless communication system 100 may be a 5G network, such as a New Radio (NR) network. In other implementations, wireless communication system 100 may be a combination of 4G and 5G networks, or other suitable radio access technologies, including IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), and IEEE 802.20. Wireless communication system 100 may support radio access technologies beyond 5G. In addition, the wireless communication system 100 can support technologies such as time division multiple access (TDMA), frequency division multiple access (FDMA), or code division multiple access (CDMA).

[0069] One or more network entities 102 may be distributed across a geographical area to form a wireless communication system 100. The network entities 102 described herein may be, include, or may be referred to as network nodes, base stations, network elements, radio access networks (RAN), base transceiver stations, access points, NodeBs, eNodeBs (eNBs), next-generation NodeBs (gNBs), or other suitable terms. Network entities 102 and UE 104 may communicate via communication link 110, which may be a wireless or wired connection. For example, network entities 102 and UE 104 may perform wireless communication (e.g., receive signaling, send signaling) via a Uu interface.

[0070] Network entity 102 can provide a geographic coverage area 112 for which it can support services (e.g., voice, video, packet data, messaging, broadcasting, etc.) for one or more UEs 104 within the geographic coverage area 112. For example, network entity 102 and UE 104 can support wireless communication of signals associated with services (e.g., voice, video, packet data, messaging, broadcasting, etc.) based on one or more radio access technologies. In some implementations, network entity 102 can be mobile, for example, a satellite associated with a non-terrestrial network. In some implementations, different geographic coverage areas 112 associated with the same or different radio access technologies may overlap, but different geographic coverage areas 112 can be associated with different network entities 102. The information and signals described herein can be represented using a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned in the description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0071] One or more UEs 104 may be distributed across a geographical area of ​​the wireless communication system 100. UE 104 may include or be referred to as a mobile device, wireless device, remote device, remote unit, handheld device, or subscriber device, or some other suitable term. In some implementations, UE 104 may be referred to as a unit, station, terminal, or client, among other examples. Alternatively or additionally, UE 104 may be referred to as an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a Machine Type Communication (MTC) device, among other examples. In some implementations, UE 104 may be stationary within the wireless communication system 100. In other implementations, UE 104 may be mobile within the wireless communication system 100.

[0072] One or more UEs 104 can be devices of different forms or with different capabilities. Some examples of UEs 104 are shown in... Figure 1 It is shown in the middle. For example... Figure 1 As shown, UE 104 can communicate with various types of devices, such as network entity 102, other UE 104, or network devices (e.g., core network 106, packet data network 108, relay devices, integrated access and backhaul (IAB) nodes, or another network device). Alternatively or additionally, UE 104 can support communication with other network entities 102 or UE 104, which can act as relays in the wireless communication system 100.

[0073] UE 104 can also support direct wireless communication with other UE 104s via communication link 114. For example, UE 104 can support direct wireless communication with other UE 104s via a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular V2X deployments, communication link 114 may be referred to as a side link. For example, UE 104 can support direct wireless communication with another UE 104 via a PC5 interface.

[0074] Network entity 102 may support communication with core network 106, or with another network entity 102, or both. For example, network entity 102 may interface with other core network 106 via one or more backhaul links 116 (e.g., via S1, N2, N3, or another network interface). Network entities 102 may communicate with each other via backhaul links 116 (e.g., via X2, Xn, or another network interface). In some implementations, network entities 102 may communicate directly with each other (e.g., between network entities 102). In some other implementations, network entities 102 may communicate with each other or indirectly (e.g., via core network 106). In some implementations, one or more network entities 102 may include sub-components, such as access network entities, which may be an example of an access node controller (ANC). The ANC may communicate with one or more UEs 104 via one or more other access network transport entities, which may be referred to as wireless heads, smart wireless heads, or transmit-receive points (TRPs).

[0075] In some implementations, network entity 102 can be configured in a decomposed architecture that can utilize a protocol stack physically or logically distributed across two or more network entities 102, such as an Integrated Access Backhaul (IAB) network, an Open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance), or a Virtualized RAN (vRAN) (e.g., a Cloud RAN (C-RAN)). For example, network entity 102 may include one or more of the following: a Central Unit (CU), a Distributed Unit (DU), a Radio Unit (RU), a RAN Intelligent Controller (RIC) (e.g., a Near-RT RIC, a Non-RT RIC), a Service Management and Orchestration (SMO) system, or any combination thereof.

[0076] An RU can also be referred to as a radio head, intelligent radio head, remote radio head (RRH), remote radio unit (RRU), or transmit-receive point (TRP). In a decomposed RAN architecture, one or more components of network entity 102 may be co-located, or one or more components of network entity 102 may be located in different locations (e.g., separate physical locations). In some implementations, one or more network entities 102 in a decomposed RAN architecture may be implemented as virtual units (e.g., virtual CU (VCU), virtual DU (VDU), virtual RU (VRU)).

[0077] The functional division among CU, DU, and RU can be flexible and can support different functions depending on which functions (e.g., network layer functions, protocol layer functions, baseband functions, radio frequency functions, and any combination thereof) are performed at the CU, DU, or RU. For example, the functional division of the protocol stack can be adopted between the CU and DU, such that the CU can support one or more layers of the protocol stack, while the DU can support one or more different layers of the protocol stack. In some implementations, the CU can host upper-layer protocol layer (e.g., Layer 3 (L3), Layer 2 (L2)) functions and signaling (e.g., Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP)). The CU can connect to one or more DUs or RUs, and one or more DUs or RUs can host lower-layer protocol layer functions and signaling, such as Layer 1 (L1) (e.g., Physical (PHY) layer) or L2 (e.g., Radio Link Control (RLC), Media Access Control (MAC) layer), and each can be at least partially controlled by the CU 160.

[0078] Alternatively, or alternatively, the functional division of the protocol stack can be adopted between DU and RU, such that DU can support one or more layers of the protocol stack, while RU can support one or more different layers of the protocol stack. DU can support one or more different cells (e.g., via one or more RUs). In some implementations, the functional division between CU and DU or between DU and RU can be within the protocol layer (e.g., some functions for the protocol layer can be performed by one of CU, DU, or RU, while other functions of the protocol layer are performed by a different one of CU, DU, or RU).

[0079] The CU can be further functionally divided into CU control plane (CU-CP) and CU user plane (CU-UP) functions. The CU can be connected to one or more DUs via mid-range communication links (e.g., F1, F1c, F1-u), while the DUs can be connected to one or more RUs via front-end communication links (e.g., open front-end (FH) interfaces). In some implementations, the mid-range or front-end communication links can be implemented based on interfaces (e.g., channels) between layers of a protocol stack, supported by corresponding network entities 102 communicating via such communication links.

[0080] Core network 106 can support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. Core network 106 can be an evolved packet core (EPC) or a 5G core network (5GC), which may include control plane entities that manage access and mobility (e.g., Mobility Management Entity (MME), Access and Mobility Management Functions (AMF)) and user plane entities that route or interconnect packets to external networks (e.g., Serving Gateway (S-GW), Packet Data Network (PDN) Gateway (P-GW), or User Plane Functions (UPF)). In some implementations, the control plane entities may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management (e.g., data bearers, signaling bearers, etc.) for one or more UEs 104 served by one or more network entities 102 associated with core network 106.

[0081] Core network 106 can communicate with packet data network 108 via one or more backhaul links 116 (e.g., via S1, N2, N2, or another network interface). Packet data network 108 may include application server 118. In some implementations, one or more UEs 104 can communicate with application server 118. UE 104 can establish a session (e.g., Protocol Data Unit (PDU) session, etc.) with core network 106 via network entity 102. Core network 106 can use the established session (e.g., established PDU session) to route traffic (e.g., control information, data, etc.) between UE 104 and application server 118. A PDU session can be one example of a logical connection between UE 104 and core network 106 (e.g., one or more network functions of core network 106).

[0082] In the wireless communication system 100, network entity 102 and UE 104 can use the resources of the wireless communication system 100 (e.g., time resources (e.g., symbols, time slots, subframes, frames, etc.) or frequency resources (e.g., subcarriers, carriers)) to perform various operations (e.g., wireless communication). In some implementations, network entity 102 and UE 104 can support different resource structures. For example, network entity 102 and UE 104 can support different frame structures. In some implementations, such as in 4G, network entity 102 and UE 104 can support a single-frame structure. In some other implementations, such as in 5G and other suitable radio access technologies, network entity 102 and UE 104 can support various frame structures (i.e., multi-frame structures). Network entity 102 and UE 104 can support various frame structures based on one or more digital technologies.

[0083] One or more digital technologies may be supported in the wireless communication system 100, and the digital technologies may include subcarrier spacing and cyclic prefix. The first digital technology (e.g., μ =0) can be associated with the first subcarrier spacing (e.g., 15 kHz) and a normal cyclic prefix. In some implementations, the first digital technique (e.g., ...) associated with the first subcarrier spacing (e.g., 15 kHz) is... μ =0) can utilize one time slot per subframe. Second digital technologies (e.g., μ =1) can be associated with the second subcarrier spacing (e.g., 30 kHz) and a normal cyclic prefix. The third digital technology (e.g., μ =2) can be associated with a third subcarrier spacing (e.g., 60 kHz) and a normal cyclic prefix or an extended cyclic prefix. A fourth digital technology (e.g., μ =3) can be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a normal cyclic prefix. A fifth digital technology (e.g., μ =4) can be associated with the fifth subcarrier spacing (e.g., 240 kHz) and the normal cyclic prefix.

[0084] The time intervals of resources (e.g., communication resources) can be organized according to frames (also called radio frames). Each frame can have a duration, for example, 10 milliseconds (ms). In some implementations, each frame can include multiple subframes. For example, each frame can include 10 subframes, and each subframe can have a duration, for example, 1 ms. In some implementations, each frame can have the same duration. In some implementations, each subframe of a frame can have the same duration.

[0085] Alternatively or concurrently, the time intervals of resources (e.g., communication resources) can be organized according to time slots. For example, a subframe may include a certain number (e.g., quantity) of time slots. The number of time slots in each subframe may also depend on one or more digital technologies supported in the wireless communication system 100. For example, a first digital technology, a second digital technology, a third digital technology, a fourth digital technology, and a fifth digital technology (i.e., ...) associated with corresponding subcarrier intervals of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz. μ =0、 μ =1、 μ =2、 μ =3、 μ =4) One time slot per subframe, two time slots per subframe, four time slots per subframe, eight time slots per subframe, and 16 time slots per subframe can be used, respectively. Each time slot can include a certain number (e.g., quantity) of symbols (e.g., OFDM symbols). In some implementations, the number (e.g., quantity) of time slots in a subframe can depend on the digital technology. For a normal cyclic prefix, a time slot can include 14 symbols. For an extended cyclic prefix (e.g., for a 60 kHz subcarrier spacing), a time slot can include 12 symbols. The relationship between the number of symbols per time slot, the number of time slots per subframe, and the number of time slots per frame for both normal and extended cyclic prefixes can depend on the digital technology. It should be understood that for the first digital technology (e.g., quantity) associated with the first subcarrier spacing (e.g., 15 kHz), μ The reference of =0 can be used interchangeably between subframes and time slots.

[0086] In the wireless communication system 100, the electromagnetic (EM) spectrum can be divided into various categories, frequency bands, frequency channels, etc., based on frequency or wavelength. For example, the wireless communication system 100 can support one or more operating frequency bands, such as frequency range names FR1 (410 MHz - 7.125 GHz), FR2 (24.25 GHz - 52.6 GHz), FR3 (7.125 GHz - 24.25 GHz), FR4 (52.6 GHz - 114.25 GHz), FR4a or FR4-1 (52.6 GHz - 71 GHz), and FR5 (114.25 GHz - 300 GHz). In some implementations, network entity 102 and UE 104 can perform wireless communication on one or more operating frequency bands. In some implementations, FR1 can be used by network entity 102 and UE 104, as well as other devices or apparatuses, for cellular communication services (e.g., control information, data). In some implementations, FR2 can be used by network entity 102 and UE 104, as well as other devices or apparatuses, for short-range, high data rate capabilities.

[0087] FR1 can be associated with one or more digital technologies (e.g., at least three digital technologies). For example, FR1 can be associated with the following: a first digital technology (e.g., μ =0), which includes a 15 kHz subcarrier spacing; second digital technology (e.g., μ =1), which includes a 30 kHz subcarrier spacing; third digital technology (e.g., μ =2), which includes a subcarrier spacing of 60 kHz. FR2 can be associated with one or more digital technologies (e.g., at least two digital technologies). For example, FR2 can be associated with a third digital technology (e.g., μ =2), which includes a 60 kHz subcarrier spacing; fourth digital technology (e.g., μ =3), which includes a subcarrier spacing of 120 kHz.

[0088] As mentioned earlier, LTM is a cell handover process triggered by MAC CE based on L1 measurements. For dual connectivity (DC) scenarios, in Release 18, LTM primarily focuses on PCell handover within the CU and PSCell handover within the SN. During the pre-Release 19 discussions, inter-SN SCG LTM was proposed, and the following consensus was reached in RP-232618: • Specifies support for Layer 2 mobility (LTM) between CUs. The next stage of issues still needs to be discussed / decided: Does it support a scenario where CU acts as the master node (MN) and CU acts as the slave node (SN)? In the case where the CU acts as the SN, is EN-DC and / or NR-NR dual connectivity (NR-DC) supported? When answering the above questions, the focus should be on actual deployment. • The case of NR-DC supported by LTM. Note the following consensus from offline sources: LTM is only important for the MCG case. In the NR-DC case, LTM on the SCG is important (e.g., in FR2), followed by LTM in the MCG with the SCG configured (SCG is not changed by the MCG LTM).

[0089] In MR-DC, the UE has a single RRC state, based on the MN RRC and a single C-plane connection toward the core network. Figure 2A-2B The control plane architectures for EN-DC and MR-DC with 5GC are shown respectively. Each radio node has its own RRC entity (E-UTRA version if the node is an eNB; NR version if the node is a gNB), which can generate RRC PDUs to be sent to the UE.

[0090] The RRC PDU generated by the SN can be transmitted to the UE via the MN. The MN always sends the initial SN RRC configuration via the MCG SRB (SRB1), but subsequent reconfigurations can be transmitted via either the MN or the SN. When transmitting the RRC PDU from the SN, the MN does not modify the UE configuration provided by the SN.

[0091] In an E-UTRA network connected to the EPC, SRB1 uses E-UTRA PDCP during initial connection establishment. If the UE supports EN-DC, regardless of whether EN-DC is configured, after initial connection establishment, the MCG SRBs (SRB1 and SRB2) can be configured by the network to use either E-UTRA PDCP or NR PDCP (either SRB1 or SRB2 is configured with E-UTRA PDCP, or both are configured with NR PDCP). Changes from E-UTRA PDCP to NR PDCP (and vice versa) are supported via a handover procedure (reconfiguration with mobility); alternatively, for the initial handover of SRB1 from E-UTRA PDCP to NR PDCP, a reconfiguration without mobility is performed before initial security activation.

[0092] If the SN is a gNB (i.e., for EN-DC, NGEN-DC, and NR-DC), the UE can be configured to establish a signaling radio bearer (SRB) (SRB3) with the SN, allowing RRC PDUs for the SN to be transmitted directly between the UE and the SN. RRC PDUs for the SN can only be transmitted directly to the UE for SN RRC reconfiguration without any coordination with the MN. If SRB3 is configured, mobility measurement reports within the SN can be transmitted directly from the UE to the SN.

[0093] Split SRBs are supported for all MR-DC options, allowing replication of RRCPDUs generated by the MN via direct paths and via the SN. Split SRBs use NR PDCP. This version of the specification does not support replication of RRCPDUs generated by the SN via MN and SN paths.

[0094] In EN-DC, the SCG configuration is maintained during UE suspension. During connection restoration, if the UE supports EN-DC restoration, the UE can be configured to release, restore, or reconfigure the SCG configuration. Otherwise, the UE releases the SCG configuration (but not the radio bearer configuration) during restoration initiation.

[0095] In an MR-DC with 5GC, the UE stores its PDCP / SDAP configuration and SCG configuration when moving to an RRC inactive location. During connection recovery, if the UE supports MR-DC recovery, it can be configured to release, restore, or reconfigure the SCG configuration. Otherwise, it releases the SCG configuration.

[0096] In MR-DC, from the UE's perspective, there are three bearer types: MCG bearer, SCG bearer, and segmented bearer. Figure 2C This illustrates the radio protocol architecture for MCG, SCG, and segmented bearers in an MR-DC (EN-DC) with EPC from the UE's perspective; and Figure 2D The radio protocol architecture for MCG, SCG, and split bearers in MR-DC (NGEN-DC, NE-DC, and NR-DC) with 5GC is shown from the UE's perspective.

[0097] In E-UTRA connected to the EPC, if the UE supports EN-DC, the network can configure E-UTRA PDCP or NR PDCP for MCG bearers terminated by the MN, regardless of whether EN-DC is configured. NR PDCP is always used for all other bearers. Changes from E-UTRA to NR PDCP or vice versa can be performed via a reconfiguration process (with or without handover), using DRB release and addition, or using the full configuration options.

[0098] In MR-DC with 5GC, NR PDCP is always used for all bearer types. In NGEN-DC, E-UTRARLC / MAC is used in MN, while NRRLC / MAC is used in SN. In NE-DC, NRRLC / MAC is used in MN, while E-UTRARLC / MAC is used in SN. In NR-DC, NRRLC / MAC is used in both MN and SN.

[0099] From a network perspective, each bearer (MCG, SCG, and segmented bearer) can terminate in MN or SN. Figure 2E The diagram illustrates the network-side protocol termination options for MCG, SCG, and segmented bearers in an MR-DC (EN-DC) with EPC, and... Figure 2F Network-side protocol termination options for MCG, SCG, and segmented bearers in MR-DC (NGEN-DC, NE-DC, and NR-DC) with 5GC are shown.

[0100] Note that even if only SCG bearers are configured for the UE, for SRB1 and SRB2, the logical channel is always configured at least in the MCG; that is, this is still an MR-DC configuration, and the PCell is always present. If only MCG bearers are configured for the UE, i.e., without SCG, this is still considered an MR-DC configuration as long as at least one of the bearers is terminated in the SN.

[0101] As described above, LTM is a process in which the gNB receives multiple L1 measurement reports from the UE and, based on these reports, changes the UE's serving cell via a cell handover command signaled through the MAC CE. The cell handover command indicates the LTM candidate cell configuration previously prepared by the gNB and provided to the UE via RRC signaling. The UE then hands over to the target cell according to the cell handover command. The LTM process can be used to reduce mobility latency.

[0102] The network can request the UE to perform early TA acquisition for a candidate cell before cell handover. Early TA acquisition is triggered by a PDCCH command or by UE-based TA measurement. Note that RAN1 confirms the working assumption that supports UE-based TA measurement (the UE derives the TA based on the Rx timing difference between the current serving cell and the candidate cell, and the TA value used for the current serving cell). The description of UE-based TA management depends on the progress of RAN1 and RAN4.

[0103] If the TA value is not provided, the network indicates in the cell handover command whether the UE should access the target cell using a random access (RA) procedure or using a PUSCH transmission with the indicated TA value. For LTM without RACH, the UE accesses the target cell via a configuration grant provided in the RRC signaling and selects a configuration grant timing associated with the beam indicated in the cell handover command. If the UE does not receive a configuration grant in the RRC signaling, it monitors the PDCCH from the target cell for dynamic scheduling during LTM cell handover. The random access procedure should not be triggered if the UE does not have a valid PUCCH resource for triggering the SR before the LTM procedure without RACH is completed.

[0104] The following principles apply to LTM: - The UE does not update its security key in LTM; and - Subsequent LTMs are supported.

[0105] LTM supports both intra-gNB-DU and inter-gNB-DU mobility within and between gNB-CUs. LTM also supports both intra-frequency and inter-frequency mobility, including mobility to inter-frequency cells that are not the current serving cell. It supports the following scenarios: - PCell handover in non-CA and non-DC scenarios; - PCell handover in CA scenarios; and - PSCell changes in dual-connectivity scenarios that do not involve the MN, i.e., PSCell changes within the SN.

[0106] While the UE has stored the LTM candidate cell configuration, the UE can also execute any L3 handover command sent by the network. This depends on the network's efforts to avoid any issues arising from conflicts between LTM execution and L3 handover execution; for example, avoiding the simultaneous transmission of LTM cell handover commands and L3 handover commands.

[0107] The cell handover command is transmitted in the MAC CE, which contains the necessary information to perform an LTM cell handover. Figure 2G The overall process for LTM is illustrated. After each LTM completion, subsequent LTMs are performed by repeating the early synchronization, LTM execution, and LTM completion steps without releasing the configuration of other LTM candidate cells.

[0108] exist Figure 2G In step 1, the UE sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates candidate cell preparation (multiple). In step 2, the gNB sends an RRCReconfiguration message to the UE, which includes the LTM candidate cell configuration of one or more candidate cells. In step 3, the UE stores the LTM candidate cell configuration and sends an RRCReconfigurationComplete message to the gNB.

[0109] At step 4a, the UE may perform DL synchronization with (multiple) candidate cells before receiving the cell handover command. It should be understood that DL synchronization for candidate cells is supported at least based on the Synchronization Signal Block (SSB) before the cell handover command.

[0110] At step 4b, if requested by the network, the UE performs early TA acquisition with (multiple) candidate cells before receiving the cell handover command. This is done via CFRA triggered by a PDCCH command from the source cell, after which the UE sends a preamble toward the indicated candidate cell. To minimize data interruption due to CFRA toward the source cell (multiple) candidate cells, the UE does not receive RAR for TA value acquisition purposes, and the TA value of the candidate cell is indicated in the cell handover command. The UE does not maintain a TA timer for the candidate cells, but relies on the network implementation to guarantee TA validity.

[0111] In step 5, the UE performs L1 measurements on the configured candidate cells(s) and sends an L1 measurement report to the gNB. The L1 measurements should be performed whenever RRC reconfiguration is applied in step 2.

[0112] In step 6, the gNB determines to perform a cell handover to the target cell and sends a MAC CE that triggers the handover via a candidate configuration index that includes the target cell. The UE hands over to the target cell and applies the configuration indicated by the candidate configuration index.

[0113] At step 7, if the UE does not have a valid TA for the target cell, the UE performs a random access procedure for the target cell.

[0114] In step 8, the UE completes the LTM cell handover process by sending an RRCReconfigurationComplete message to the target cell. If the UE has already performed the RA procedure in step 7, the UE considers the LTM execution to be successfully completed when the random access procedure is successfully completed. For LTM without RACH, the UE considers the LTM execution to be successfully completed when it determines that the network has successfully received its first UL data. The UE determines the successful reception of its first UL data by receiving the PDCCH of the UE's C-RNTI in the addressing target cell, and the UE's C-RNTI schedules new transmissions after the first UL data.

[0115] In some cases, steps 4-8 can be executed multiple times using the LTM candidate cell configuration provided in step 2 to perform subsequent LTM.

[0116] Figure 2GThe procedures described on the air interface apply to both intra-DU LTM and inter-DU LTM. The overall LTM procedures on the F1-C and Xn interfaces have been captured in the prior art and will be repeated in this disclosure.

[0117] However, in the DC scenario, details regarding inter-SN SCG LTM have not yet been discussed. For example, how to coordinate indexes related to inter-SN SCGLTM candidate cell configuration to support L1 measurement reports.

[0118] Embodiments of this disclosure provide a communication solution. In this solution, a first base station (such as a master node) sends a first request message to a second base station (such as a candidate target slave node). This first request message may include a first indicator associated with the SCG LTM of a user equipment. The second base station may send a first response message to the first base station, and this first response message includes an SCG LTM candidate configuration for each candidate PSCell. In this solution, the first base station may provide the user equipment with an SCG LTM CSI resource configuration and an SCG LTM candidate configuration for each candidate PSCell. Therefore, the SCG LTM CSI resource configuration can be used for L1 measurement, and the SCG LTM candidate configuration can be used to connect to a target PSCell. Thus, inter-SN SCG LTM can be supported. The principles and implementation of this disclosure will be described in detail below with reference to the accompanying drawings.

[0119] Figure 2H A schematic diagram of an example communication network 200 in which some embodiments of this disclosure may be implemented is shown. For example... Figure 2H As shown, the communication network 200 may include a first base station 210, a second base station 220-1, a second base station 220-2, a third base station 230, and a UE 250.

[0120] Each of the first base station 210, the second base station 220-1, the second base station 220-2, and the third base station 230 can be a gNB. For example, the first base station 210 can be a master node (MN), and each of the second base stations 220-1, the second base station 220-2, and the third base station 230 can be a slave node (SN). Figure 2H As shown, the first base station 210 and the third base station 230 can serve the UE 230.

[0121] Although considering the mobility of UE 250, this mobility can be intra-MN or inter-SN mobility. The third base station 230 can be considered a source base station, such as a source SN (S-SN). UE 250 can switch to the second base station 220-1; for example, UE 250 can move to location 251, in which case the second base station 220-1 is the target base station, such as a target SN (T-SN). Similarly, UE 250 can switch to the second base station 220-2; UE 250 can move to location 252, in which case the second base station 220-2 is the target base station, such as a target SN (T-SN).

[0122] For ease of description, the second base station 220-1 and the second base station 220-2 may be referred to individually or collectively as the second base station 220, such as a candidate target SN (or candidate SN). It should be understood that... Figure 2H The number of devices shown is for illustrative purposes only and does not imply any limitation on this disclosure. For example, during movement between SNs, there may be multiple candidate target SNs for UE 250.

[0123] For ease of description, some related terms are provided below:

[0124] LTM Candidate Cells: Configure candidate cells for LTM for the UE. Multiple LTM candidate cells may be prepared for the UE, and these LTM candidate cells can belong to the same or different candidate nodes. For inter-SN SCG LTM, LTM candidate cells are LTM candidate PSCells, where these LTM candidate PSCells can belong to the same or different candidate SNs. In some use cases, a PSCell in the source SN can also be an LTM candidate PSCell.

[0125] LTM candidate cell configuration: The configuration associated with LTM candidate cells. An LTM candidate cell configuration can be a complete LTM candidate cell configuration or an incremental (differential) configuration relative to the LTM reference configuration. Each LTM candidate cell configuration is identified by an index, referred to as the LTM candidate cell configuration index, LTM candidate configuration index, or other names. In one example, the LTM candidate cell configuration index is... LTM-CandidateId This is used to identify the LTM candidate cell configuration. For better understanding, the LTM candidate cell configuration is also called the LTM incremental configuration. Additionally, for SCG LTM, the LTM candidate cell configuration is also called the LTM candidate PSCell configuration, the LTM candidate SCG configuration, or the SCG LTM candidate configuration.

[0126] LTM Reference Configuration: The configuration provided to the UE by the network is common to all configured LTM candidate cells. It is used by the UE to generate a complete LTM candidate cell configuration (i.e., by applying the LTM candidate cell configuration on top of the LTM Reference Configuration). Additionally, for SCG LTM, the LTM Reference Configuration includes an MCG portion and / or an SCG portion, where the MCG portion of the LTM Reference Configuration references the MCG LTM Reference Configuration, and the SCG portion of the LTM Reference Configuration references the SCG LTM Reference Configuration.

[0127] Complete LTM candidate cell configuration: This configuration contains all the necessary fields required to perform the LTM cell handover procedure. This configuration can be an LTM candidate cell configuration, or it can be generated by applying an LTM candidate cell configuration to an LTM reference configuration.

[0128] MN: In DC, a radio access node that provides a connection to the control plane of the core network.

[0129] SN: In DC, a radio access node that does not have a control plane connection with the core network and provides additional resources to the UE.

[0130] SCG: In a DC, a group of serving cells associated with a SN, including PSCell and optionally one or more SCells.

[0131] It should be understood that this disclosure discusses SCG LTM between SNs. For example, information or messages exchanged between MN and SN (such as S-SN or candidate T-SN) are directed at SCG LTM without explicit description.

[0132] Further reference Figure 3 , Figure 3 Signaling diagrams of a communication process 300 for SCG LTM according to some example embodiments of this disclosure are shown. For example... Figure 2H As shown, procedure 300 may involve UE 250, first base station (MN) 210, third base station (S-SN), and second base station (candidate T-SN) 220-1 and 220-2. It should be understood that procedure 300 can be applied to other communication scenarios, which will not be described in detail hereafter.

[0133] In process 300, at point 310, the first base station 210 sends a first request message to the second base station 220. For example, the first request message may be sent to each of the second base station 220-1 and the second base station 220-2. The first request message may include a first indicator indicating that the first request message is associated with an LTM, for example, the first indicator is associated with the SCG LTM of the UE 250. For example, the first request message may be implemented as an SN add request message. In some example embodiments, the first indicator may also be referred to as a first LTM indicator or a first SCG LTM indicator.

[0134] In some example embodiments, the first indicator may be carried in a specific information element (IE) of the first request message. For example, the first indicator may be included in a conditional PSCell add information request IE embedded in the SN add request message, for example, with an enumeration value of TRUE. For example, the first indicator may be included in a newly defined IE in the SN add request message.

[0135] In some implementations, the first request message may include a list of suggested PSCells. In this case, the second base station 220 can configure SCG LTM by considering the list of suggested PSCells.

[0136] In some example embodiments, the first base station 210 may determine one or more suggested PSCells (recommended PSCells) for each of the second base stations 220 for the UE 250. As a non-limiting example, the first base station 210 may determine one or more suggested PSCells including PSCell 1, PSCell 2, and PSCell 3 of the second base station 220-1, and PSCell 4, PSCell 5, and PSCell 6 of the second base station 220-2. In some examples, a first request message to the second base station 220-1 may include a list of suggested PSCells: PSCell 1, PSCell 2, and PSCell 3; a first request message to the second base station 220-2 may include a list of suggested PSCells: PSCell 4, PSCell 5, and PSCell 6. It should be understood that although three suggested PSCells are included in the example, in some other examples, there may be more or fewer suggested PSCells.

[0137] In some examples, the list of suggested PSCells can be provided via measurement results. In some examples, the list of suggested PSCells can be included in a CG-ConfigInfo message embedded in the SN Add Request message, in which case the CG-ConfigInfo message includes the list of suggested PSCells.

[0138] In some implementations, the first request message may include an SCG LTM reference configuration. For example, if the first base station 210 has an available SCG LTM reference configuration, the first request message may include that SCG LTM reference configuration. In some example embodiments, the first request message may also include an MCG LTM reference configuration.

[0139] In some examples, the SCG LTM reference configuration may be included in the first indicator. In some examples, the SCG LTM reference configuration may be included in a CG-ConfigInfo message embedded in the SN Add Request message, in which case the CG-ConfigInfo message includes the SCG LTM reference configuration.

[0140] In some implementations, the first request message may include a request for an SCG LTM reference configuration. For example, if the first base station 210 does not have an available SCG LTM reference configuration, the first request message may include an indication that the first base station 210 is requesting the second base station 220 to provide an SCG LTM reference configuration. For example, this indication may be included in a first indication.

[0141] In some examples, the first request message to the second base station 220-1 may include an indication for requesting the SCG LTM reference configuration, while the first request message to the second base station 220-2 may not include an indication for requesting the SCG LTM reference configuration. In other words, the second base station 220-1 is requested to provide the SCG LTM reference configuration.

[0142] It should be understood that even if the first base station 210 does not have an available SCG LTM reference configuration, the first request message may not include an indication for requesting the SCG LTM reference configuration.

[0143] In some implementations, the first request message may include the maximum number of candidate PSCells that the second base station 220 can prepare for SCG LTM. For example, the maximum number of candidate PSCells may be included in the first indicator. In some examples, the first request message to the second base station 220-1 may include N1 to indicate the maximum number of candidate PSCells that the second base station 220-1 can prepare for SCG LTM, for example, N1=3. In some examples, the first request message to the second base station 220-2 may include N2 to indicate the maximum number of candidate PSCells that the second base station 220-2 can prepare for SCG LTM, for example, N2=3 or N2=2. In some examples, the first request message to the second base station 220-2 (or the second base station 220-1) may not include the maximum number of candidate PSCells.

[0144] At point 312, the second base station 220-1 sends a first response message to the first base station 210, and at point 314, the second base station 220-2 sends a first response message to the first base station 210. The first response message may include the SCG LTM candidate configuration for each candidate PSCell. For example, the first response message may be implemented as adding a request confirmation message to the SN.

[0145] In some example embodiments, the received first request message may not include a list of suggested PSCells, in which case the second base station 220 may determine one or more candidate PSCells and further determine an SCG LTM candidate configuration for each candidate PSCell. In some other example embodiments, the received first request message may include a list of suggested PSCells, in which case the second base station 220 may select one or more candidate PSCells from the list and further determine an SCG LTM candidate configuration for each candidate PSCell. In some other example embodiments, the received first request message may include a list of suggested PSCells, in which case the second base station 220 may use the list of suggested PSCells as one or more candidate PSCells and further determine an SCG LTM candidate configuration for each candidate PSCell. In some examples, if the received first request message includes a maximum number of candidate PSCells, then the number of one or more candidate PSCells is not greater than that maximum number.

[0146] In some examples, SCG LTM candidate configurations can be included in a CG-Config message or a CG-CandidateList message embedded in an SN add request confirmation message. In this case, the CG-Config message or CG-CandidateList message includes the SCG LTM candidate configuration for each candidate PSCell.

[0147] In some examples, if the first request message includes an SCG LTM reference configuration, the SCG LTM candidate configuration for each candidate PSCell in the first response message can be represented as an incremental candidate configuration relative to the SCG LTM reference configuration. In this case, the overhead can be reduced.

[0148] In some implementations, the first response message may include one or more candidate PSCells. For example, one or more IDs of one or more candidate PSCells provided by the second base station 220 may be included in the first response message. For example, one or more candidate PSCells are PSCells prepared by the second base station 220 for SCG LTM; for example, one or more candidate PSCells may be referred to as one or more prepared candidate PSCells.

[0149] In some implementations, the first response message may include one or more reference signal (RS) configurations for one or more candidate PSCells. For example, the first response message may include an RS configuration for each candidate PSCell, where the RS may be a synchronization signal / physical broadcast channel block (SSB) and / or a channel state information reference signal (CSI-RS). For example, the RS configuration may be an RS resource configuration, where the RS resource configuration may be at least one of the following: a non-zero power channel state information reference signal (NZP-CSI-RS) resource, a channel state information synchronization signal / physical broadcast channel block (CSI-SSB) resource, or a channel state information interference management (CSI-IM) resource.

[0150] In some implementations, the first response message may include an SCG LTM reference configuration. In some examples, the first response message may include an SCG LTM reference configuration if the first request message does not include an SCG LTM reference configuration, or if the first request message includes a request for an SCG LTM reference configuration (such as an indication that the second base station 220 provides an SCG LTM reference configuration).

[0151] In process 300, at point 320, the first base station 210 determines the SCG LTM CSI resource configuration. This SCG LTM CSI resource configuration can be a common SCG LTM CSI resource configuration used for all candidate PSCells.

[0152] It should be understood that, although operation 320 is... Figure 3 Operations 312 and 314 are shown subsequently, but in some other examples, operation 320 may be performed earlier, for example, before operation 310. In some implementations, the first request message may include SCG LTM CSI resource configuration. In some example embodiments, the SCG LTM CSI resource configuration may be included in the first indicator of the first request message. In some example embodiments, the SCG LTM CSI resource configuration may be included in a CG-ConfigInfo message embedded in the SN add request message. In this case, the CG-ConfigInfo message includes the SCG LTM CSI resource configuration.

[0153] In some implementations, where the first request message includes SCG LTM CSI resource configuration, the first response message may include SCG LTM CSI report configuration for each candidate PSCell. In some example embodiments, the SCG LTM CSI report configuration for each candidate PSCell may be included in a CG-Config message or a CG-CandidateList message embedded in the SN add request confirmation message. In this case, the CG-Config message or CG-CandidateList message includes the SCG LTM CSI report configuration for each candidate PSCell.

[0154] In some other implementations, operation 320 may be performed after operations 312 and 314. In some examples, the first base station 210 may determine (or generate) the SCG LTM CSI resource configuration based on the first response message.

[0155] The SCG LTM CSI resource configuration is common to all candidate PSCells. The SCG LTM CSI resource configuration includes one or more RS configurations for one or more candidate PSCells. In some examples, each RS configuration for a candidate PSCell is associated with an LTM Candidate ID (LTM-CandidateId). In other words, one or more RS configurations are associated with a unique LTM-CandidateId. In some examples, the LTM Candidate ID (LTM-CandidateId) may be determined (or assigned) by the first base station 210, and this LTM Candidate ID can be used to identify the SCG LTM candidate configuration.

[0156] In process 300, at point 330, the first base station 210 may send a second modification request message to the third base station 230, and at point 335, the third base station 230 may send a second modification response message to the first base station 210. As described above, the third base station 230 may be the S-SN of the UE 250. In some examples, the second modification request message may be implemented as an SN modification request, and the second modification response message may be implemented as an SN modification request acknowledgment.

[0157] In some implementations, the second modification request message includes a third indicator that can indicate that the second modification request message is for an LTM. In some examples, the third indicator (or referred to as the third LTM indicator) is associated with the SCG LTM of UE 250.

[0158] In some example embodiments, a third indicator may be carried within a specific IE of the second modification request message. For example, the third indicator may be included in a conditional PSCell add information modification request IE or a conditional PSCell change information update IE embedded in the SN modification request message, for example, with an enumerated value of TRUE. For example, the third indicator may be included in a newly defined IE within the SN modification request message.

[0159] In some implementations, the second modification request message may include the SCG LTM CSI resource configuration. In some examples, the SCG LTM CSI resource configuration may be included in a third indicator. In some examples, the SCG LTM CSI resource configuration may be included in a CG-ConfigInfo message embedded in the SN modification request message; that is, the CG-ConfigInfo message includes the SCG LTM CSI resource configuration.

[0160] In some implementations, the second modification request message may include a request for an SCG LTM reference configuration. For example, if the first base station 210 does not have an available SCG LTM reference configuration, the second modification request message may include an indication that the first base station 210 is requesting the third base station 230 to provide an SCG LTM reference configuration. For example, this indication may be included in a third indicator.

[0161] For example, if neither the first request message nor the first response message includes an SCG LTM reference configuration, and the first base station 210 does not have an available SCG LTM reference configuration, then the second modification request message may include an indication that the third base station 230 provides an SCG LTM reference configuration.

[0162] In some implementations, the second modification response message may include SCGLTM CSI report configuration for the serving cell of UE 250, where the serving cell is provided by the third base station 230. In some examples, the SCGLTM CSI report configuration for the serving cell may be used to configure LTM L1 measurement reports on the serving cell (serving PSCell) in the third base station 230.

[0163] In some implementations, the second modification response message may include an SCG LTM reference configuration. For example, if the second modification request message is requesting an SCG LTM reference configuration, the third base station 230 may provide the SCG LTM reference configuration in the second modification response message.

[0164] It should be understood that if the first base station 210 already has an SCG LTM CSI report configuration for the serving cell, operations 330 and 335 can be omitted in process 300, or operations 330 and 335 can be performed before operation 310.

[0165] In process 300, at 340, the first base station 210 sends a first modification request message to the second base station 220. At 342, the first base station 210 receives a first modification response message from the second base station 220-1, and at 344, receives a first modification response message from the second base station 220-2. In some examples, the first modification request message can be implemented as an SN modification request, and the first modification response message can be implemented as an SN modification request acknowledgment.

[0166] In some implementations, the first modification request message includes a third indicator that can indicate that the first modification request message is for an LTM. In some examples, the third indicator (or referred to as the third LTM indicator) is associated with the SCG LTM of UE 250.

[0167] In some example embodiments, a third indicator may be carried within a specific IE of the first modification request message. For example, the third indicator may be included in a conditional PSCell add information modification request IE or a conditional PSCell change information update IE embedded in the SN modification request message, for example, with an enumerated value of TRUE. For example, the third indicator may be included in a newly defined IE in the SN modification request message.

[0168] In some implementations, the first modification request message may include the SCG LTM CSI resource configuration. In some examples, the SCG LTM CSI resource configuration may be included in a third indicator. In some examples, the SCG LTM CSI resource configuration may be included in a CG-ConfigInfo message embedded in the SN modification request message; that is, the CG-ConfigInfo message includes the SCG LTM CSI resource configuration.

[0169] In some implementations, the first modification request message may include the SCG LTM reference configuration. For example, if neither the first request message nor the first response message includes the SCG LTM reference configuration, then the first modification request message may include the SCG LTM reference configuration.

[0170] In some examples, the SCG LTM reference configuration may be included in a third indicator. In some examples, the SCG LTM reference configuration may be included in a CG-ConfigInfo message embedded in the SN modification request message; that is, the CG-ConfigInfo message includes the SCG LTM reference configuration.

[0171] In some implementations, the first modification response message may include an SCG LTMCSI report configuration for each candidate PSCell. In some examples, the SCG LTM CSI report configuration for each candidate PSCell may be used to configure the LTM L1 measurement report on that candidate PSCell in the second base station 220.

[0172] For example, a first modification response message from the second base station 220-1 may include a first SCG LTM CSI report configuration for candidate PSCell 1, a second SCG LTM CSI report configuration for candidate PSCell 2, and a third SCG LTM CSI report configuration for candidate PSCell 3. Similarly, a first modification response message from the second base station 220-2 may include a fourth SCG LTM CSI report configuration for candidate PSCell 4, a fifth SCG LTM CSI report configuration for candidate PSCell 5, and a sixth SCG LTM CSI report configuration for candidate PSCell 6.

[0173] In some other implementations, the first modification response message may include an updated SCG LTM candidate configuration for each candidate PSCell. In some example embodiments, if the first request message does not include an SCG LTM reference configuration, but the first modification request message does include an SCG LTM reference configuration, the second base station 220 may determine an updated SCG LTM candidate configuration for each candidate PSCell, for example, an incremental candidate configuration relative to the SCG LTM reference configuration for each candidate PSCell.

[0174] It should be understood that if the first base station 210 already has an SCG LTM CSI report configuration for each candidate PSCell, operations 340 to 344 in process 300 can be omitted. In some examples, at 312, the second base station 220-1 has provided an SCG LTM CSI report configuration for each candidate PSCell (e.g., PSCell 1-3), but at 314, the second base station 220-2 has not provided an SCG LTM CSI report configuration for each candidate PSCell (e.g., PSCell 4-6), then the first modification request and response message associated with the second base station 220-2 can be executed.

[0175] In process 300, at point 346, the first base station 210 can receive the required message from the second base station 220-1, at point 248, it can receive the required message from base station 220-2, and at point 349, it can send the required response message to each of the second base stations 220. In some examples, the required message can be implemented as an SN-modified required message, and the required response message can be implemented as an SN-modified acknowledgment message.

[0176] In some implementations, the required message may include a fourth indicator that indicates the required message is for LTM. In some examples, the fourth indicator (or referred to as the fourth LTM indicator) is associated with UE 250's SCGLTM.

[0177] In some example embodiments, the fourth indicator may be carried in a specific IE of the desired message. For example, the fourth indicator may be included in a conditional PSCell add information modification request IE or CPAC information request IE embedded in the SN modification request message, for example, with an enumerated value of TRUE. For example, the fourth indicator may be included in a newly defined IE in the SN modification request message.

[0178] In some implementations, the required message may include at least one candidate PSCell, for example, at least one ID of at least one candidate PSCell from one or more (e.g., multiple) candidate PSCells. In some implementations, the required message may include an updated SCG LTM candidate configuration for at least one candidate PSCell.

[0179] In some examples, at least one candidate PSCell indicated by the desired message can be associated with an updated SCG LTM candidate configuration. In some examples, at least one candidate PSCell indicated by the desired message can be associated with an updated SCGLTM CSI reporting configuration.

[0180] For example, the candidate PSCells of the second base station 220-1 include PSCell 1, PSCell 2, and PSCell 3. If a desired message from the second base station 220-1 includes PSCell 1, it can indicate that PSCell 1 is associated with an updated SCG LTM candidate configuration (and / or an updated SCG LTM CSI reporting configuration). For example, the SCG LTM candidate configurations (and / or SCG LTM CSI reporting configurations) of PSCell 2 and PSCell 3 have not been updated.

[0181] For example, the candidate PSCells of the second base station 220-1 include PSCell 1, PSCell 2, and PSCell 3. If the desired message from the second base station 220-1 includes PSCell 1 and PSCell 2, it can instruct PSCell 1 and PSCell 2 to be associated with the updated SCG LTM candidate configuration (and / or the updated SCG LTM CSI reporting configuration), while PSCell 3 is no longer a candidate PSCell. In this case, the candidate PSCells of the second base station 220-1 include PSCell 1 and PSCell 2.

[0182] It should be understood that operations 346 to 349 in process 300 can be omitted if the candidate PSCell and SCG LTM candidate configurations (and / or SCG LTM CSI report configurations) of the second base station 220 remain unchanged. In some examples, the SCG LTM candidate configurations (and / or SCG LTM CSI report configurations) of the candidate PSCells (e.g., PSCell 1-3) of the second base station 220-1 have been updated, but the SCG LTM candidate configurations (and / or SCG LTM CSI report configurations) of the candidate PSCells (e.g., PSCell 4-6) of the second base station 220-2 remain unchanged, in which case the required messages and required response messages associated with the second base station 220-1 can be executed.

[0183] In process 300, at point 350, the first base station 210 sends an RRCReconfiguration message to the UE 250. In some implementations, the RRCReconfiguration message may include one or more of the following: SCG LTM candidate configuration for each candidate PSCell, SCG LTM CSI report configuration for each candidate PSCell, and SCG LTM CSI resource configuration for all candidate PSCells. At point 355, the UE 250 responds to the first base station 210 with an RRCReconfigurationComplete message. In some implementations, the RRCReconfiguration message is embedded in another RRCReconfiguration message sent from the first base station 210 to the UE 250 at point 350, and the RRCReconfigurationComplete message is embedded in another RRCReconfigurationComplete message sent from the UE 250 to the first base station 210 at point 355.

[0184] In some implementations, during procedure 300, at point 355, the third base station 230 sends an RRCReconfiguration message to the UE 250. In some implementations, the RRCReconfiguration message may include one or more of the following: SCG LTM candidate configuration for each candidate PSCell, SCG LTMCSI report configuration for each candidate PSCell, and SCG LTM CSI resource configuration for all candidate PSCells. At point 355, the UE 250 responds to the third base station 230 with an RRCReconfigurationComplete message.

[0185] In some example embodiments, the RRCReconfiguration message may include SCG LTM candidate configuration and SCG LTM CSI report configuration for each candidate PSCell, while the SCG LTM CSI resource configuration for all candidate PSCells may be provided to UE 250 via another separate message.

[0186] In procedure 300, at point 360, UE 250 may perform L1 measurements and may send an L1 measurement report to third base station 230. In some examples, UE 250 may perform L1 measurements on candidate PSCells and may also perform L1 measurements on the serving cell. In some examples, the L1 measurement report may include L1 measurement results for each candidate PSCell, and the candidate PSCells may include L1 measurement results for the serving cell. In some examples, UE 250 determines which candidate PSCells should be reported along with the L1 measurement results.

[0187] In process 300, at point 370, the third base station 230 sends an LTM cell handover command to the UE 250. In some implementations, the LTM cell handover command may include an LTM candidate ID (LTM-CandidateId), and this LTM cell handover command may be used to trigger an SCG LTM cell handover.

[0188] In some implementations, the LTM cell handover command may include the ID of the target PSCell, which is one of the candidate PSCells. In some examples, the third base station 230 may determine the target PSCell based on an L1 measurement report.

[0189] In process 300, at point 380, the third base station 230 sends a notification message to the first base station 210. For example, this notification message can be implemented as an LTM cell change notification message.

[0190] In some implementations, the notification message may include the ID of the target PSCell, which can be used to instruct the UE 250 to initiate an LTM cell handover command for SCG LTM.

[0191] At 390, UE 250 can perform SCG LTM, meaning that UE 250 can connect to the target PSCell via a random access procedure or a RACH-free procedure. For example, at 390, assume that the target PSCell is provided by the second base station 220-1, and UE 250 is switched to the second base station 220-1.

[0192] In procedure 300, at point 395, UE 250 sends an RRCReconfigurationComplete message to the first base station 210. In some implementations, the RRCReconfigurationComplete message may include an LTM candidate ID (LTM-CandidateId), which may indicate that the SCG LTM candidate configuration associated with that LTM candidate ID (LTM-CandidateId) is applied. In some examples, at point 395, the RRCReconfigurationComplete message may be embedded in another message sent to the first base station 210, such as a ULInformationTransferMRDC message.

[0193] According to the reference Figure 3 In some embodiments discussed, the first base station (e.g., MN) can initiate inter-SN SCG LTM preparation, for example, by sending a first request message to the second base station; and assign an ID (i.e., LTM candidate ID) to the SCG LTM candidate configuration. Thus, inter-SN SCG LTM can be supported.

[0194] Further reference Figure 4 This figure illustrates a signaling diagram of a communication process 400 for SCG LTM according to some example embodiments of this disclosure. For example... Figure 2H As shown, procedure 400 may involve UE 250, first base station (MN) 210, third base station (S-SN), and second base stations (candidate T-SN) 220-1 and 220-2. It should be understood that procedure 400 can be applied to other communication scenarios, which will not be described in detail hereafter.

[0195] In process 400, at point 401, the third base station 230 sends a second request message to the first base station 210. This second request message may include a second indicator indicating that the second request message is associated with an LTM, for example, the second indicator is associated with the SCG LTM of the UE 250. For example, the second request message may be implemented as an SN change request message. In some example embodiments, the second indicator may also be referred to as a second LTM indicator or a second SCG LTM indicator.

[0196] In some example embodiments, the second indicator may be carried within a specific IE of the second request message. For example, the second indicator may be included in a conditional PSCell change information request IE embedded in an SN change request message, for example, with an enumeration value of TRUE. For example, the second indicator may be included in a newly defined IE within the SN change request message.

[0197] In some examples, the second indicator may include one used to indicate whether the second request message is for LTM initialization, LTM modification, or LTM cancellation.

[0198] In some implementations, the second request message may include a list of suggested PSCells. In some example embodiments, the third base station 230 may suggest or recommend one or more suggested PSCells for the UE 250. For example, the list of suggested PSCells may be used by (multiple) second base stations to configure SCG LTM.

[0199] In some examples, the list of suggested PSCells may be included in the CG-Config message or CG-CandidateList message embedded in the SN change request message; that is, the CG-Config message or CG-CandidateList message includes the list of suggested PSCells.

[0200] In some implementations, the second request message may include at least one ID of at least one second base station. For example, at least one ID of at least one second base station may be included in the second indicator. In some example embodiments, the list of suggested PSCells may include one or more suggested PSCells belonging to (located at) more than one second base station, in which case the second request message may include more than one ID of more than one second base station.

[0201] For example, the second request message may include the first ID of the second base station 220-1 and a list of associated suggested PSCells (such as PSCell1-3), and the second ID of the second base station 220-2 and a list of associated suggested PSCells (such as PSCell4-6).

[0202] In some implementations, the second request message may include an SCG LTM reference configuration. In some examples, the third base station 230 may have an available SCG LTM reference configuration, and the third base station 230 may provide this SCG LTM reference configuration to the first base station 210 via the second request message.

[0203] In some examples, the SCG LTM reference configuration may be included in the second indicator. In some examples, the SCG LTM reference configuration may be included in the CG-Config message or CG-CandidateList message embedded in the SN change request message, in which case the CG-Config message or CG-CandidateList message includes the SCG LTM reference configuration.

[0204] In process 400, at point 410, the first base station 210 sends a first request message to the second base station 220. The first request message can be implemented as an SN add request message. The first request message may include a first indicator.

[0205] In some implementations, the second request message may include at least one ID of at least one second base station, and then the first base station 210 may send the first request message to each of the at least one second base station.

[0206] In some implementations, the first request message may include a list of suggested PSCells. For example, if the second request message includes a list of suggested PSCells, then the list of suggested PSCells may be included in the first request message destined for the associated second base station. In some examples, the list of suggested PSCells may be included in a CG-ConfigInfo message embedded in an SN add request message, in which case the CG-ConfigInfo message includes the list of suggested PSCells.

[0207] In some implementations, the first request message may include an SCG LTM reference configuration. For example, if the second request message includes an SCG LTM reference configuration, or if the first base station 210 has an available SCG LTM reference configuration, then the SCG LTM reference configuration may be included in the first request message destined for the second base station 220.

[0208] In some implementations, the first request message may include a request for an SCG LTM reference configuration, for example, if the first base station 210 does not have an available SCG LTM reference configuration. For example, the second request message may not include an SCG LTM reference configuration.

[0209] It should be understood that the recommended list of PSCells and / or SCG LTM reference configurations are determined (or provided) by the third base station 230 (i.e., the S-SN of UE250).

[0210] In process 400, at 412, the first base station 210 receives a first response message from the second base station 220-1, and at 414, it receives a first response message from the second base station 220-2.

[0211] In some implementations, the first response message may include an SCG LTM candidate configuration for each candidate PSCell. In some examples, if the first request message includes an SCG LTM reference configuration, the SCG LTM candidate configuration for each candidate PSCell in the first response message may be represented as an incremental candidate configuration relative to the SCG LTM reference configuration.

[0212] In some implementations, the first response message may include one or more candidate PSCells. For example, one or more candidate PSCells may be selected by the second base station 220 from a list of suggested PSCells. In some implementations, the first response message may include one or more RS configurations of one or more candidate PSCells.

[0213] In some implementations, the first response message may include an SCG LTM reference configuration, for example, if the first request message includes a request for an SCG LTM reference configuration.

[0214] It should be understood that the information included in the first response message may refer to references Figure 3 The points discussed will not be repeated in this article.

[0215] In process 400, at point 420, the first base station 210 determines the SCG LTM CSI resource configuration. This SCG LTM CSI resource configuration can be a common SCG LTM CSI resource configuration for all candidate PSCells. In some examples, the first base station 210 may determine (or generate) the SCG LTM CSI resource configuration based on a first response message.

[0216] SCG LTM CSI resource configuration includes one or more (e.g., multiple) candidate PSCells and one or more (e.g., multiple) RS configurations. In some examples, each RS configuration of a candidate PSCell is associated with an LTM Candidate ID (LTM-CandidateId). In other words, one or more (e.g., multiple) RS configurations are associated with a unique LTM-CandidateId. In some examples, the LTM Candidate ID (LTM-CandidateId) may be determined (or assigned) by the first base station 210, and this ID may be used to identify the SCG LTM candidate configuration.

[0217] In some other implementations, such as the reference Figure 3 As discussed, operation 420 can be performed before operation 410. For example, the first request message may include SCG LTM CSI resource configuration. For example, the first response message may include SCG LTM CSI report configuration for each candidate PSCell.

[0218] In process 400, at 430, the first base station 210 may send a second modification request message to the third base station 230, and at 435, the third base station 230 may send a second modification response message to the first base station 210. In some examples, the second modification request message may be implemented as an SN modification request, and the second modification response message may be implemented as an SN modification request acknowledgment.

[0219] In some implementations, the second modification request message includes a third indicator. In some implementations, the second modification request message may include SCG LTM CSI resource configuration.

[0220] In some implementations, the second modification request message may include a request for an SCG LTM reference configuration. For example, if the first base station 210 does not have an available SCG LTM reference configuration (e.g., the second request message does not include an SCG LTM reference configuration), the second modification request message may include an indication that the first base station 210 is requesting the third base station 230 to provide an SCG LTM reference configuration.

[0221] In some implementations, the second modification response message may include the SCGLTM CSI report configuration for the serving cell of UE 250.

[0222] exist Figure 4 In the middle, operations 440 to 455 can be referenced accordingly. Figure 3 Operations 340 to 355 in the code will not be repeated here.

[0223] In process 400, at point 402, the first base station 210 sends a second response message to the third base station 230. For example, the second response message can be implemented as an SN change confirmation message.

[0224] In some implementations, the second response message may indicate the preparation of one or more candidate PSCells for SCG LTM. In some examples, the second response message may include one or more IDs of one or more candidate PSCells, and one or more IDs of at least one second base station. For example, the one or more candidate PSCells may be determined by the second base station 220-1, for example, selected from a list of suggested PSCells. For example, each of the one or more candidate PSCells is configured with an SCG LTM candidate configuration by the second base station.

[0225] exist Figure 4 In the middle, operations 460 to 495 can be referred to accordingly. Figure 3 Operations 360 to 395 in the text will not be repeated here.

[0226] According to the reference Figure 4 In some embodiments discussed, a third base station (e.g., S-SN) can initiate inter-SN SCG LTM preparation, for example, by sending a second request message to a first base station (e.g., MN), and the first base station (e.g., MN) can assign an ID (i.e., LTM candidate ID) to the SCG LTM candidate configuration. Thus, inter-SN SCG LTM can be supported.

[0227] According to the reference Figure 3 or Figure 4 In some embodiments discussed, a first base station (e.g., MN) obtains the RS configuration for each candidate PSCell from a second base station (e.g., a candidate T-SN) and generates a common SCG LTM CSI resource configuration for all candidate PSCells. The SCG LTM CSI resource configuration includes the RS configuration for all candidate PSCells, and each RS configuration is associated with an LTM candidate ID assigned to that SCG LTM candidate configuration. In this solution, the first base station (e.g., MN) sends the SCG LTM CSI resource configuration to the second base station (e.g., a candidate T-SN) and the third base station (e.g., an S-SN), and each of the second base station (e.g., a candidate T-SN) and the third base station (e.g., an S-SN) can generate an SCG LTM CSI report configuration independently. In this case, the LTM candidate ID can be generated by MN, and L1 measurement reporting for inter-SN SCG LTM can be supported.

[0228] Further reference Figure 5 , Figure 5 Signaling diagrams for a communication process 500 for SCG LTM according to some example embodiments of this disclosure are shown. For example... Figure 2H As shown, procedure 500 may involve UE 250, first base station (MN) 210, third base station (S-SN), and second base stations (candidate T-SN) 220-1 and 220-2. It should be understood that procedure 500 can be applied to other communication scenarios, which will not be described in detail hereafter.

[0229] In process 500, at point 501, the third base station 230 sends a second request message to the first base station 210. For example, the second request message can be implemented as an SN change request message.

[0230] In some implementations, the second request message may include a second indicator. In some implementations, the second request message may include a list of suggested PSCells. In some implementations, the second request message may include at least one ID of at least one second base station. In some implementations, the second request message may include an SCG LTM reference configuration. Detailed information regarding the information in the second request message may refer to… Figure 4 Those points discussed in the previous article will not be repeated here.

[0231] In some implementations, if the third base station 230 already has an SCG LTM CSI resource configuration, the second request message may include that SCG LTM CSI resource configuration. In some examples, the SCG LTM CSI resource configuration may be included in a CG-Config message or a CG-CandidateList message embedded in the SN change request message; that is, the CG-Config message or the CG-CandidateList message includes the SCG LTM CSI resource configuration.

[0232] In process 500, at point 510, the first base station 210 sends a first request message to the second base station 220. The first request message can be implemented as an SN add request message. The first request message may include a first indicator.

[0233] In some implementations, the first request message may include a list of PSCells suggested or recommended by the third base station 230. In some implementations, the first request message may include an SCG LTM reference configuration, or a request for an SCG LTM reference configuration.

[0234] In some implementations, the first request message may include SCG LTM CSI resource configuration. For example, if the second request message includes SCG LTM CSI resource configuration, the SCG LTM CSI resource configuration may be determined by the third base station 230.

[0235] At position 512, the first base station 210 receives a first response message from the second base station 220-1, and at position 514, it receives a first response message from the second base station 220-2. The first response message can be implemented by adding a request confirmation message to the SN. The first response message may include the SCG LTM candidate configuration for each candidate PSCell.

[0236] In some implementations, the first response message may include one or more candidate PSCells. In some implementations, the first response message may include one or more RS configurations of one or more candidate PSCells. In some implementations, the first response message may include an SCG LTM reference configuration, for example, if the first request message includes a request for an SCGLTM reference configuration.

[0237] In some implementations, the first response message may include the SCG LTM CSI report configuration for each candidate PSCell, for example, if the first request message includes the SCG LTM CSI resource configuration.

[0238] In process 500, at point 512, the first base station 210 sends a third request message to the third base station 230, the third request message including a third indicator. For example, the third request message can be implemented as an SN modification request message.

[0239] In some implementations, the third request message may include one or more RS configurations for one or more candidate PSCells. In some examples, one or more RS configurations for one or more candidate PSCells may be included in a third indicator. In some examples, one or more RS configurations for one or more candidate PSCells may be included in a CG-ConfigInfo message embedded in an SN modification request message; that is, the CG-ConfigInfo message includes the RS configuration for each candidate PSCell.

[0240] In some implementations, the third request message may include an SCG LTM reference configuration. For example, if the second request message does not include an SCG LTM reference configuration, but the first response message does, then the first base station 210 may provide the SCG LTM reference configuration to the third base station 230. In some examples, the SCG LTM reference configuration may be included in a third indicator. In some examples, the SCG LTM reference configuration may be included in a CG-ConfigInfo message embedded in an SN modification request message; that is, the CG-ConfigInfo message includes the SCG LTM reference configuration.

[0241] In some other implementations, the third request message may include a request for an SCG LTM reference configuration. For example, if the first base station 210 does not have an available SCG LTM reference configuration (e.g., neither the second request message nor the first response message includes an SCG LTM reference configuration), the first base station 210 may send an indication to the third base station 230 in the third request message, indicating that the third base station 230 provides the SCG LTM reference configuration. In some examples, the indication for requesting the SCG LTM reference configuration may be included in a third indicator.

[0242] In process 500, at point 522, the third base station 230 determines the SCG LTM CSI resource configuration. In some implementations, the third base station 230 may generate the SCG LTM CSI resource configuration based on a third request message.

[0243] The SCG LTM CSI resource configuration is common to all candidate PSCells. The SCG LTM CSI resource configuration includes one or more RS configurations for one or more candidate PSCells. In some examples, each RS configuration for a candidate PSCell is associated with an LTM Candidate ID (LTM-CandidateId). In other words, one or more RS configurations are associated with a unique LTM-CandidateId. In some examples, the LTM Candidate ID (LTM-CandidateId) may be determined (or assigned) by a third base station 230, and this ID may be used to identify the SCG LTM candidate configuration.

[0244] In process 500, at point 525, the third base station 230 sends a third response message to the first base station 210. The third response message can be implemented as an SN modification request confirmation message. The third response message includes the SCG LTMCSI resource configuration determined by the third base station 230.

[0245] In some implementations, the third response message may include the SCG LTM reference configuration, for example, if the third request message includes a request for the SCG LTM reference configuration.

[0246] As described above, the second request message may include SCG LTM CSI resource configuration, meaning that the third base station 230 already possesses SCG LTM CSI resource configuration, for example, before operation 501. In this case, operations 520 to 525 can be omitted.

[0247] exist Figure 5 In the context, operations 540 to 549 can refer to... Figure 3 Operations 340 to 349 are discussed, so they will not be repeated in this article.

[0248] In process 500, at 530, the first base station 210 sends a second modification request message to the third base station 230, and at 535, the third base station 230 sends a second modification response message to the first base station 210.

[0249] In some examples, the second modification request message can be implemented as an SN modification request message, and the second modification response message can be implemented as an SN modification request confirmation message.

[0250] In some implementations, the second modification request message may include a third indicator. In some implementations, the second modification request message may include an SCG LTM candidate configuration for each candidate PSCell. In some examples, the SCG LTM candidate configuration for each candidate PSCell may be included in the third indicator. In some examples, the SCG LTM candidate configuration for each candidate PSCell may be included in a CG-ConfigInfo message embedded in the SN modification request message; that is, the CG-ConfigInfo message includes the SCG LTM candidate configuration for each candidate PSCell.

[0251] In some implementations, the second modification response message may include an RRCReconfiguration message generated by the third base station 230. In some examples, the RRCReconfiguration message generated by the third base station 230 may include one or more of the following: SCG LTM candidate configuration for each candidate PSCell, SCG LTM CSI report configuration for each candidate PSCell, and SCG LTM CSI resource configuration for all candidate PSCells.

[0252] exist Figure 5 In the text, operations 550-555, 502, and 560-590 can respectively refer to... Figure 3 Operations 350-355 in the middle Figure 4 Operation 402 in the middle, and Figure 3 Operations 360-390 in the code will not be repeated here.

[0253] In procedure 500, at point 595, UE 250 sends an RRCReconfigurationComplete message to the first base station 210. In some implementations, the RRCReconfigurationComplete message may include the Physical Cell ID (PCI) of the target PSCell to which UE 250 connects after the SCG LTM cell handover. In some implementations, the RRCReconfigurationComplete message may include the Absolute Radio Frequency Channel Number (ARFCN) of the target PSCell.

[0254] According to the reference Figure 5In some embodiments discussed, a third base station (e.g., S-SN) can initiate inter-SN SCG LTM preparation, for example, by sending a second request message to a first base station (e.g., MN), and the third base station (e.g., S-SN) can assign an ID (i.e., LTM candidate ID) to the SCG LTM candidate configuration. Thus, inter-SN SCG LTM can be supported.

[0255] According to the reference Figure 5 In some embodiments discussed, after obtaining the RS configuration for each candidate PSCell, the first base station (e.g., MN) sends the RS configuration to the third base station (e.g., S-SN), and the third base station (e.g., S-SN) generates a common SCG LTM CSI resource configuration for all candidate PSCells. In this case, the LTM candidate ID can be generated by the S-SN, and L1 measurement reports for inter-SN SCG LTM can be supported.

[0256] In this disclosure, an RRCReconfigurationComplete message can be sent from the UE to a first base station (e.g., MN), wherein the RRCReconfigurationComplete message can indicate the SCGLTM candidate configuration applied by the UE for the execution of SCG LTM. For example, the RRCReconfigurationComplete message can include an index of the SCG LTM candidate configuration applied by the UE for the execution of SCG LTM, wherein the index can be an LTM candidate ID. Therefore, the MN can know the configuration applied at the UE, so that data forwarding toward the candidate SN can be performed in a timely manner for the SCG bearer terminated by the MN.

[0257] In this disclosure, after sending an LTM cell handover command to the UE, a third base station (e.g., S-SN) sends a notification message to a first base station (e.g., MN) to instruct it to initiate an LTM cell handover command to the UE. This notification message may include the ID of the target PSCell (such as index, PCI, ARFCN, etc.). Therefore, the MN can promptly learn of the target PSCell, and data forwarding towards the candidate SN can be performed in a timely manner against the SCG bearers terminated by the MN.

[0258] In some embodiments of this disclosure, an SCG LTM reference configuration can be used, which can be determined (generated or provided) by a first base station (e.g., MN), a second base station (e.g., a candidate T-SN), or a third base station (e.g., S-SN). Therefore, incremental configuration for inter-SN SCG LTM can be supported, and overhead can be reduced.

[0259] In this disclosure, a first indicator (first LTM indicator) is introduced in an SN add request message, for example, for an inter-SN SCG LTM preparation initiated by an MN, to indicate that the request is for an SCG LTM. A second indicator (second LTM indicator) is introduced in an SN change request message, for example, for an inter-SN SCG LTM preparation initiated by an SN, to indicate that the request is for an SCG LTM. A third indicator (third LTM indicator) is introduced in a node modify request message, for example, for a modification initiated by an MN, to indicate that the request is to update the SCG LTM configuration. A fourth indicator (fourth LTM indicator) is introduced in a node modify request message, for example, for a modification initiated by a candidate T-SN, to update the candidate SCG LTM configuration prepared by the candidate T-SN. Therefore, the initiation and modification of inter-SN SCG LTM can be supported, and the efficiency of SCG LTM can be improved.

[0260] It should be understood that the example embodiments or implementations described above are for illustrative purposes only and are not intended to limit the scope of the invention. By modifying, adding, deleting, or updating some information or steps in the example embodiments or implementations described above, other example embodiments or implementations can be obtained. For example, if all candidate PSCells belong to the same candidate T-SN (such as the second base station 220-1), the second base station 220-2 can be removed from the above process. For example, if a candidate PSCell belongs to more than two candidate T-SNs, there may be multiple second base stations in the process, and each candidate T-SN is similar to the second base station 220. For example, there may be one or more candidate PSCells belonging to a third base station (e.g., an S-SN). In this case, the process between the first base station (e.g., MN) and the second base station (e.g., a candidate T-SN) can also be applied between the first base station (e.g., MN) and the third base station (e.g., an S-SN). For example, the third base station can be considered as one of the candidate T-SNs.

[0261] Figure 6 An example of a device 600 suitable for implementing embodiments of the present disclosure is shown. Device 600 may be an example of a base station or UE as described herein. Device 600 may support wireless communication with a first base station 210, a second base station 220, a third base station 230, a user equipment 250, or any combination thereof. Device 600 may include components for bidirectional communication, including components for transmitting and receiving communications, such as a processor 602, a memory 604, a transceiver 606, and optionally an I / O controller 608. These components may be electrically communicated or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, or electrically) via one or more interfaces (e.g., a bus).

[0262] Processor 602, memory 604, transceiver 606, or various combinations thereof, or various components thereof, may be examples of components for performing various aspects of the present disclosure as described herein. For example, processor 602, memory 604, transceiver 606, or various combinations thereof, or components thereof, may support methods for performing one or more of the operations described herein.

[0263] In some implementations, processor 602, memory 604, transceiver 606, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuitry system). This hardware may include a processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured to or otherwise support components for performing the functions described herein. In some implementations, processor 602 and memory 604 coupled to it may be configured to perform one or more of the functions described herein (e.g., instructions stored in memory 604 are executed by processor 602).

[0264] For example, processor 602 may support wireless communication at device 600 according to examples disclosed herein. Processor 602 may be configured to operate to support components for the operations described above.

[0265] Processor 602 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some implementations, processor 602 may be configured to operate a memory array using a memory controller. In other implementations, the memory controller may be integrated into processor 602. Processor 602 may be configured to execute computer-readable instructions stored in memory (e.g., memory 604) to cause device 600 to perform various functions of this disclosure.

[0266] Memory 604 may include random access memory (RAM) and read-only memory (ROM). Memory 604 may store computer-readable, computer-executable code, including instructions that, when executed by processor 602, cause device 600 to perform the various functions described herein. This code may be stored in a non-transitory computer-readable medium, such as system memory or another type of memory. In some implementations, this code may not be directly executable by processor 602, but may cause a computer (e.g., at compile and execution time) to perform the functions described herein. In some implementations, memory 604 may include a basic I / O system (BIOS) or similar system that controls basic hardware or software operations, such as interaction with peripheral components or devices.

[0267] I / O controller 608 can manage input and output signals for device 600. I / O controller 608 can also manage peripheral devices not integrated into device 600. In some implementations, I / O controller 608 can represent a physical connection or port to an external peripheral. In some implementations, I / O controller 608 can utilize an operating system such as iOS®, Android®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or another known operating system. In some implementations, I / O controller 608 can be implemented as part of a processor (such as processor 606). In some implementations, a user can interact with device 600 via I / O controller 608 or via hardware components controlled by I / O controller 608.

[0268] In some implementations, device 600 may include a single antenna 610. However, in other implementations, device 600 may have more than one antenna 610 (i.e., multiple antennas), including multiple antenna panels or antenna arrays that can concurrently transmit or receive multiple wireless transmissions. Transceiver 606 may communicate bidirectionally via one or more antennas 610, wired or wireless links, as described herein. For example, transceiver 606 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. Transceiver 606 may also include a modem for modulating packets to provide modulated packets to one or more antennas 610 for transmission, and for demodulating packets received from one or more antennas 610. Transceiver 606 may include one or more transmitter chains, one or more receiver chains, or combinations thereof.

[0269] The transmitter chain can be configured to generate and transmit signals (e.g., control information, data, packets). The transmitter chain may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques, such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes, such as phase shift keying (PSK) or quadrature amplitude modulation (QAM). The transmitter chain may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over a wireless medium. The transmitter chain may also include one or more antennas 610 for transmitting the amplified signal over the air or wireless medium.

[0270] The receiver chain can be configured to receive signals (e.g., control information, data, packets) via a wireless medium. For example, the receiver chain may include one or more antennas 610 for receiving signals over the air or via a wireless medium. The receiver chain may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. The receiver chain may include at least one demodulator configured to demodulate the received signal and obtain the transmitted data by reversing the modulation technique applied during signal transmission. The receiver chain may include at least one decoder for decoding and processing the demodulated signal to receive the transmitted data.

[0271] Figure 7 Examples of processors 700 for implementing some embodiments of the present disclosure are shown. Processor 700 may be an example of a processor configured to perform various operations according to the examples described herein. Processor 700 may include a controller 702 configured to perform various operations according to the examples described herein. Processor 700 may optionally include at least one memory 704, such as an L1 / L2 / L3 cache. Additionally or alternatively, processor 700 may optionally include one or more arithmetic logic units (ALUs) 706. One or more of these components may be electronically or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses).

[0272] Processor 700 may be a processor chipset and includes a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receive, acquire, retrieve, send, output, forward, store, determine, identify, access, write, read) according to examples as described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory native to the processor chipset (e.g., processor 700) or included in the processor chipset), or other memory (e.g., random access memory (RAM), read-only memory (ROM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), static random access memory (SRAM), ferroelectric random access memory (FeRAM), magnetic random access memory (MRAM), resistive random access memory (RRAM), flash memory, phase-change memory (PCM), etc.).

[0273] Controller 702 can be configured to manage and coordinate various operations of processor 700 (e.g., signaling, receiving, acquiring, retrieving, sending, outputting, forwarding, storing, determining, identifying, accessing, writing, and reading) to enable processor 700 to support various operations according to the examples described herein. For example, controller 702 can operate as a control unit of processor 700, generating control signals that manage the operation of various components of processor 700. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating the timing of operations.

[0274] Controller 702 may be configured to fetch (e.g., fetch, retrieve, receive) instructions from memory 704 and determine subsequent instructions(s) to be executed, enabling processor 700 to support various operations as described herein. Controller 702 may be configured to track memory addresses of instructions associated with memory 704. Controller 702 may be configured to decode instructions to determine the operation to be performed and its operands. For example, controller 702 may be configured to interpret instructions and determine control signals to be output to other components of processor 700, enabling processor 700 to support various operations as described herein. Alternatively or additionally, controller 702 may also be configured to manage data flow within processor 700. Controller 702 may be configured to control data transfers between registers, arithmetic logic unit (ALU), and other functional units of processor 700.

[0275] Memory 704 may include one or more caches (e.g., memory native to processor 700 or included in processor 700) or other memories such as RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some implementations, memory 704 may be located inside or on the processor chipset (e.g., native to processor 700). In other implementations, memory 704 may be located outside the processor chipset (e.g., remote from processor 700).

[0276] Memory 704 may store computer-readable, computer-executable code, including instructions that, when executed by processor 700, cause processor 700 to perform the various functions described herein. This code may be stored in a non-transitory computer-readable medium, such as system memory or another type of memory. Controller 702 and / or processor 700 may be configured to execute computer-readable instructions stored in memory 704 to cause processor 700 to perform various functions (e.g., functions or tasks supporting transmit power prioritization). For example, processor 700 and / or controller 702 may be coupled to or connected to memory 704, and processor 700, controller 702, and memory 704 may be configured to perform the various functions described herein. In some examples, processor 700 may include multiple processors, and memory 704 may include multiple memories. One or more processors may be coupled to one or more memories, which may be configured individually or collectively to perform the various functions described herein.

[0277] One or more ALU 706s can be configured to support various operations as described herein. In some implementations, one or more ALU 706s may be located within or on a processor chipset (e.g., processor 700). In other implementations, one or more ALU 706s may be located outside the processor chipset (e.g., processor 700). One or more ALU 706s can perform one or more operations on data, such as addition, subtraction, multiplication, and division. For example, one or more ALU 706s can receive input operands and an operand code that determines the operation to be performed. One or more ALU 706s can be configured with various logic and arithmetic circuitry, including adders, subtractors, shifters, and logic gates, to process and manipulate data according to the operations. Alternatively, one or more ALU 706s may support logical operations such as AND, OR, XOR, NOR, and NAND, thereby enabling one or more ALU 706s to handle conditional operations, comparisons, and bitwise operations.

[0278] Processor 700 may support wireless communication according to examples disclosed herein. Processor 700 may be configured or operable to support components for the operations described in some embodiments of this disclosure.

[0279] Figure 8 A flowchart of a method 800 performed by a first base station according to this disclosure is shown. The operation of method 800 can be implemented by a device or component thereof as described herein. For example, the operation of method 800 can be performed by… Figure 2H The first base station 210 performs this function. In some implementations, the device can execute a set of instructions to control the functional elements of the device to perform the function. Alternatively or concurrently, the device can use dedicated hardware to perform aspects of the function.

[0280] At 810, the method may include: sending a first request message to a second base station, the first request message including a first indicator associated with the SCG LTM of the user equipment. The operation at 810 may be performed according to examples as described herein. In some implementations, aspects of the operation at 810 may be performed by a first base station 210, as referenced... Figure 2H As stated above.

[0281] At 820, the method may include: receiving a first response message from a second base station, the first response message including an SCG LTM candidate configuration for each of a plurality of candidate PSCells of the second base station. The operation at 820 may be performed according to examples as described herein. In some implementations, aspects of the operation at 820 may be performed by a first base station 210, as referenced... Figure 2H As stated above.

[0282] At 830, the method may include: sending to the user equipment an SCG LTM candidate configuration and an SCG LTM CSI resource configuration for each of a plurality of candidate PSCells, wherein the SCG LTM CSI resource configuration includes a plurality of RS configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate ID. The operation at 830 may be performed according to the examples described herein. In some implementations, aspects of the operation at 830 may be performed by the first base station 210, as referenced... Figure 2H As stated above.

[0283] Figure 9 A flowchart of a method 900 performed by a second base station according to this disclosure is shown. The operation of method 900 can be implemented by a device or component thereof as described herein. For example, the operation of method 900 can be performed by… Figure 2HThe second base station 220 in the system performs this function. In some implementations, the device can execute a set of instructions to control the functional elements of the device to perform the function. Alternatively, the device can use dedicated hardware to perform aspects of the function.

[0284] At 910, the method may include: receiving a first request message from a first base station, the first request message including a first indicator associated with the SCG LTM of the user equipment. The operation at 910 can be performed according to examples as described herein. In some implementations, aspects of the operation at 910 may be performed by a second base station 220, as referenced... Figure 2H As stated above.

[0285] In step 920, the method may include: sending a first response message to a first base station, the first response message including an SCG LTM candidate configuration for each of a plurality of candidate PSCells for a second base station. The operation of 920 may be performed according to examples as described herein. In some implementations, aspects of the operation of 920 may be performed by the second base station 220, as referenced... Figure 2H As stated above.

[0286] Figure 10 A flowchart of a method 1000 performed by a third base station according to this disclosure is shown. The operation of method 1000 can be implemented by a device or component thereof as described herein. For example, the operation of method 1000 can be performed by… Figure 2H The third base station 230 in the system performs this function. In some implementations, the device can execute a set of instructions to control the functional elements of the device to perform the function. Alternatively, the device can use dedicated hardware to perform aspects of the function.

[0287] At 1010, the method may include: receiving a second modification request message from a first base station, the second modification request message including a third indicator associated with the SCG LTM of the user equipment. The operation at 1010 can be performed according to examples as described herein. In some implementations, aspects of the operation at 1010 may be performed by a third base station 230, as referenced... Figure 2H As stated above.

[0288] At 1020, the method may include: sending a second modified response message to a first base station, the second modified response message including SCG LTM CSI report configuration for the serving cell of the user equipment. The operation at 1020 can be performed according to the examples described herein. In some implementations, aspects of the operation at 1020 may be performed by a third base station 230, as referenced... Figure 2H As stated above.

[0289] Figure 11A flowchart of method 1100 performed by a UE according to this disclosure is shown. The operation of method 1100 may be implemented by a device or its components, as described herein. For example, the operation of method 1100 may be performed by… Figure 2H The UE 250 executes the function. In some implementations, the device can execute a set of instructions to control the functional elements of the device to perform the function. Alternatively, the device can use dedicated hardware to perform aspects of the function.

[0290] At 1110, the method may include: receiving from a first base station an SCG LTM candidate configuration for each of a plurality of candidate PSCells among one or more second base stations, and an SCG LTM CSI resource configuration, wherein the SCG LTM CSI resource configuration includes a plurality of RS configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate ID. The operation at 1110 may be performed according to the examples described herein. In some implementations, aspects of the operation at 1110 may be performed by UE 250, as referenced... Figure 2H As stated above.

[0291] At 1120, the method may include: receiving an SCG LTM cell handover command from a third base station, the SCG LTM cell handover command including a target PSCell from a plurality of candidate PSCells, wherein the target PSCell is associated with a target base station in one or more second base stations. The operation at 1120 may be performed according to examples as described herein. In some implementations, aspects of the operation at 1120 may be performed by UE 250, as referenced... Figure 2H As stated above.

[0292] At 1130, the method may include: switching from the serving cell of the third base station to the target PSCell of the target base station based on an SCG LTM cell handover command. The operation at 1130 can be performed according to the examples described herein. In some implementations, aspects of the operation at 1130 may be performed by the UE 250, as referenced... Figure 2H As stated above.

[0293] It should be noted that the methods described herein describe possible implementations, and the operations and steps can be rearranged or otherwise modified, and other implementations are possible. Furthermore, two or more aspects from the methods can be combined.

[0294] The various illustrative blocks and components disclosed herein can be implemented or executed using a general-purpose processor, DSP, ASIC, CPU, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware component or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but alternatively, the processor may be any processor, controller, microcontroller or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration).

[0295] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Features implementing the functions can also be physically located in various locations, including being distributed such that portions of the functions are implemented at different physical locations.

[0296] Computer-readable media include both non-transitory computer storage media and communication media, with communication media including any medium that facilitates the transfer of a computer program from one place to another. Non-transitory storage media can be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example, non-transitory computer-readable media can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, optical disc (CD) ROM or other optical disc storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

[0297] As used herein, including in the claims, the article “a” preceding an element is unrestricted and should be understood to refer to “at least one” or “one or more” of those elements. The terms “a,” “at least one,” “one or more,” and “at least one of one or more” are interchangeable. As used herein, including in the claims, the use of “or” in a list of items (e.g., a list of items beginning with phrases such as “at least one of…” or “one or more of…” or “one or two of…”) indicates an inclusive list, such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Furthermore, as used herein, the phrase “based on” should not be construed as a reference to a closed set of conditions. For example, an example step described as “based on condition A” without departing from the scope of this disclosure could be based on both condition A and condition B. In other words, as used herein, the phrase “based on” should be interpreted in the same manner as the phrase “at least partially based on.” Furthermore, as used herein, including in the claims, “set” can include one or more elements.

[0298] The description provided herein is intended to enable those skilled in the art to make or use this disclosure. Various modifications to this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A first base station, comprising: At least one memory; as well as At least one processor, coupled to the at least one memory and configured such that the first base station: Send a first request message to the second base station, the first request message including a first indicator associated with mobility LTM triggered by the user equipment's secondary cell group SCG layer 1 or layer 2; Receive a first response message from the second base station, the first response message including SCG LTM candidate configuration for each of the plurality of candidate primary and secondary cell PSCells of the second base station; as well as The user equipment is sent the SCG LTM candidate configuration and the SCG LTM channel state information (CSI) resource configuration for each of the plurality of candidate PSCells, wherein the SCG LTM CSI resource configuration includes a plurality of reference signal (RS) configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate identifier (ID).

2. The first base station according to claim 1, wherein the at least one processor is further configured to cause the first base station to: Determine the SCG LTM CSI resource configuration, and wherein, The first request message also includes the SCG LTM CSI resource configuration.

3. The first base station according to claim 1, wherein the first response message further includes the plurality of RS configurations of the plurality of candidate PSCells, and wherein the at least one processor is further configured to cause the first base station to: The SCG LTM CSI resource configuration is determined based on the first response message.

4. The first base station according to claim 1, wherein the at least one processor is further configured to cause the first base station to: A third request message is sent to a third base station, the third request message including the plurality of RS configurations of the plurality of candidate PSCells, and a third indicator associated with the SCG LTM; and A third response message is received from the third base station, the third response message including the SCG LTM CSI resource configuration.

5. The first base station according to claim 4, wherein the third request message further includes an SCG LTM reference configuration.

6. The first base station according to claim 4, wherein the third request message further includes a request for the SCG LTM reference configuration, and the third response message further includes the SCG LTM reference configuration.

7. The first base station according to claim 1, wherein the at least one processor is further configured to cause the first base station to: Receive a second request message from a third base station, the second request message including a second indicator associated with the SCG LTM; and A second response message is sent to the third base station, the second response message indicating the plurality of candidate PSCells for the SCG LTM.

8. The first base station according to claim 7, wherein the second request message further includes one of the following: The ID of the second base station, Recommended list of PSCells SCG LTM reference configuration, or The SCG LTM CSI resource configuration.

9. The first base station according to claim 1, wherein the first request message further includes one of the following: A list of recommended PSCells; SCG LTM Reference Configuration; Request for the SCG LTM reference configuration; The SCG LTM CSI resource configuration; or The maximum number of candidate PSCells.

10. The first base station according to claim 1, wherein the first response message further includes one of the following: The multiple IDs of the multiple PSCells; SCG LTM Reference Configuration; The plurality of RS configurations of the plurality of candidate PSCells; or SCG LTM CSI report configuration for each of the plurality of candidate PSCells.

11. The first base station of claim 1, wherein the at least one processor is further configured to cause the first base station to: A first modification request message is sent to the second base station, the first modification request message including a third indicator associated with the SCG LTM; and A first modification response message is received from the second base station, the first modification response message including the SCG LTM CSI report configuration for each of the plurality of candidate PSCells.

12. The first base station according to claim 11, wherein the first modification request message further includes one of the following: The SCG LTM CSI resource configuration, or SCG LTM Reference Configuration.

13. The first base station according to claim 1, wherein the at least one processor is further configured to cause the first base station to: Send a second modification request message to a third base station, the second modification request message including a third indicator associated with the SCG LTM; and The user equipment receives a second modification response message from the third base station, the second modification response message including the SCG LTM CSI report configuration for the serving cell of the user equipment.

14. The first base station according to claim 13, wherein the second modification request message further comprises one of the following: The SCG LTM CSI resource configuration, or Request for SCG LTM reference configuration.

15. The first base station according to claim 1, wherein the at least one processor is further configured to cause the first base station to: A notification message is received from a third base station. The notification message includes the ID of the target PSCell among the plurality of candidate PSCells. The notification message indicates that an SCG LTM cell handover command is initiated to the user equipment associated with the target PSCell.

16. The first base station according to claim 1, wherein the at least one processor is further configured to cause the first base station to: The user equipment receives a reconfiguration complete message, the reconfiguration complete message including the LTM candidate ID, wherein the LTM candidate ID indicates the SCG LTM candidate configuration applied by the user equipment.

17. A second base station, comprising: At least one memory; as well as At least one processor, the at least one processor being coupled to the at least one memory and configured to cause the second base station to: Receive a first request message from the first base station, the first request message including a first indicator associated with mobility LTM triggered by the secondary cell group SCG layer 1 or layer 2 of the user equipment; as well as A first response message is sent to the first base station, the first response message including the SCG LTM candidate configuration for each of the multiple candidate primary and secondary cell PSCells of the second base station.

18. A third base station, comprising: At least one memory; as well as At least one processor, coupled to the at least one memory and configured such that the third base station: A second modification request message is received from the first base station, the second modification request message including a third indicator associated with a mobility LTM triggered by a secondary cell group SCG layer 1 or layer 2 of the user equipment; as well as A second modification response message is sent to the first base station. The second modification response message includes the SCG LTM Channel State Information (CSI) report configuration for the serving cell of the user equipment.

19. A user equipment, comprising: At least one memory; as well as At least one processor, coupled to the at least one memory and configured such that the user equipment: The first base station receives a mobility LTM candidate configuration triggered by the secondary cell group SCG layer 1 or layer 2 for each candidate PSCell in a plurality of candidate primary and secondary cell PSCells for one or more second base stations, as well as an SCG LTM channel state information (CSI) resource configuration, wherein the SCG LTM CSI resource configuration includes a plurality of reference signal (RS) configurations for the plurality of candidate PSCells, and each of the plurality of RS configurations is associated with an LTM candidate identifier (ID). Receive an SCG LTM cell handover command from a third base station, the SCG LTM cell handover command including a target PSCell from the plurality of candidate PSCells, wherein the target PSCell is associated with a target base station from the one or more second base stations; as well as Based on the SCG LTM cell handover command, the user switches from the serving cell of the third base station to the target PSCell of the target base station.

20. The user equipment of claim 19, wherein the at least one processor is further configured to cause the user equipment to: A reconfiguration completion message is sent to the first base station. The reconfiguration completion message includes the LTM candidate ID, wherein the LTM candidate ID indicates the SCG LTM candidate configuration applied by the user equipment.

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