WO2025033902A1

WO2025033902A1 - Method and apparatus for establishing a dual-connectivity in a wireless communication system

Info

Publication number: WO2025033902A1
Application number: PCT/KR2024/011518
Authority: WO
Inventors: Weiwei Wang; Hong Wang; Lixiang Xu
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2023-08-09
Filing date: 2024-08-05
Publication date: 2025-02-13
Anticipated expiration: 2026-02-09
Also published as: CN119485410A

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The present disclosure provides a node in a wireless communication system and methods performed by the same. A method performed by a second node in a wireless communication system includes: transmitting a first message, to a third node, wherein the first message is used for requesting to configure at least one of a candidate first cell for a first node or a second cell associated with the candidate first cell, wherein the first message includes indication information associated with a configuration request, which is used for indicating a configuration associated with the first message; and receiving a response message for the first message, from the third node, wherein the response message is used for providing configuration information of a secondary cell group or a candidate secondary cell group serving the first node.

Description

METHOD AND APPARATUS FOR ESTABLISHING A DUAL-CONNECTIVITY IN A WIRELESS COMMUNICATION SYSTEM

The present disclosure relates generally to a technical field of wireless communication systems, and more specifically, to a method and apparatus for establishing a dual-connectivity in a wireless communication system.

5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in “Sub 6GHz” bands such as 3.5GHz, but also in “Above 6GHz” bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

Moreover, there has been ongoing standardization in air interface architecture/protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture/service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

The present disclosure relates to a method and apparatus for establishing a dual-connectivity in a wireless communication system.

According to an aspect of an exemplary embodiment, there is provided a communication method in a wireless communication.

Aspects of the present disclosure provide efficient communication methods in a wireless communication system.

The above and other aspects, features and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is an exemplary system architecture of System Architecture Evolution (SAE);

FIGURE 2 is an exemplary system architecture according to various embodiments of the present disclosure;

FIGURE 3 shows an example method flowchart about configuration for dual-connectivity according to embodiments of the present disclosure;

FIGURE 4 shows an example method flowchart about process of CHO with SCG according to embodiments of the present disclosure;

FIGURE 5 shows an example method flowchart about process of LTM with SCG according to embodiments of the present disclosure;

FIGURE 6 shows an example method flowchart about process of determining whether a random access process is needed autonomously according to embodiments of the present disclosure;

FIGURE 7 shows an example method flowchart about process of determining whether a random access process is needed based on a pre-configuration of the network according to embodiments of the present disclosure;

FIGURE 8 shows an example method flowchart about process of determining whether a random access process is needed based on an handover indication of the network according to embodiments of the present disclosure;

FIGURE 9 shows an example method flowchart about process of LTM-based SCG addition according to embodiments of the present disclosure;

FIGURE 10 shows a flowchart of a method performed by a second node in a wireless communication system according to embodiments of the present disclosure;

FIGURE 11 shows a flowchart of a method performed by a third node in a wireless communication system according to embodiments of the present disclosure; and

FIGURE 12 shows a schematic diagram of a node in a wireless communication system according to embodiments of the present disclosure.

FIGURE 13 illustrates the configuration of a UE in a wireless communication system according to various embodiments.

FIGURE 14 illustrates the configuration of a base station or a network entity in a wireless communication system according to various embodiments.

Embodiments of the present disclosure provide a method performed by a second node in a wireless communication system, which includes: transmitting a first message to a third node, wherein the first message is used for requesting to configure a candidate first cell for the first node and/or a second cell associated with the candidate first cell, wherein the first message includes indication information associated with a configuration request, which is used for indicating a configuration associated with the first message; and receiving a response message for the first message from the third node, wherein the response message is used for providing configuration information of a secondary cell group or a candidate secondary cell group serving the first node, and the response message includes indication information associated with a configuration response, and the indication information associated with a configuration response indicates a configuration associated with the response message.

According to embodiments of the present disclosure, the first message further includes at least one of the following: indication information for reconfiguration without synchronization, which is used for indicating to the third node that synchronization is not required when the first node accesses the second cell; indication information of an accessed cell, which is used for indicating a third cell accessed by the first node, wherein the third cell is one of candidate first cells; first secondary cell group configuration indication information, which is used for indicating configuration information required for the first node to access the secondary cell group.

According to embodiments of the present disclosure, the indication information associated with a configuration request and/or the indication information associated with a configuration response are used to configure the second cell associated with the candidate first cell, wherein the indication information associated with a configuration request and/or the indication information associated with a configuration response include at least one of the following: association identification information, identification information of an associated first cell, and identification information of an associated first node.

According to embodiments of the present disclosure, the identification information of the associated first node is identification information of the first node used on a second interface different from a first interface, wherein the first interface is an interface between the second node and the third node.

According to embodiments of the present disclosure, the response message further includes at least one of the following: cell group configuration information, which includes at least one of radio link control (RLC) configuration, logical channel configuration, media access control (MAC) layer configuration, physical layer configuration and cell configuration; and uplink synchronization configuration response indication information, which includes configuration information required for acquiring synchronization information of the second cell before the first node accesses the second cell.

According to embodiments of the present disclosure, the method further includes: transmitting a first user configuration message to the first node, wherein the first user configuration message includes information for configuring the first node to perform primary cell switch.

According to embodiments of the present disclosure, the first user configuration message includes at least one of the following: third secondary cell group configuration indication information, which is used for indicating configuration information required for the first node to access the secondary cell group; and synchronization configuration indication information, which is used for indicating synchronization-related configuration information required for the first node to access the second cell.

Embodiments of the present disclosure provide a method performed by a third node in a wireless communication system, which includes: receiving a first message from a second node, wherein the first message is used for requesting to configure a candidate first cell for the first node and/or a second cell associated with the candidate first cell, wherein the first message includes indication information associated with a configuration request, which is used for indicating a configuration associated with the first message; and transmitting a response message for the first message to the second node, wherein the response message is used for providing configuration information of a secondary cell group or a candidate secondary cell group serving the first node, and the response message includes indication information associated with a configuration response, and the indication information associated with a configuration response indicates a configuration associated with the response message.

According to embodiments of the present disclosure, the indication information associated with a configuration request and/or the indication information associated with a configuration response are used to configure the second cell associated with the candidate first cell, wherein the indication information associated with a configuration request and/or the indication information associated with a configuration response include at least one of the following: association identification information, identification information of an associated first cell and identification information of an associated first node.

Embodiments of the present disclosure provide a node device in a wireless communication system, including a transceiver; and a processor coupled to the transceiver and configured to perform any method performed by a second node and/or a third node in a wireless communication system according to embodiments of the present disclosure.

Embodiments of the present disclosure provide a computer-readable medium having stored thereon computer-readable instructions that, when executed by a processor, implement any method performed by a second node and/or a third node in a wireless communication system according to embodiments of the present disclosure.

The present application claims priority to China Patent Application No. 202311002331.4 filed on August 09, 2023. The contents of the above-identified patent documents are incorporated herein by reference.

In order to meet an increasing demand for wireless data communication services since a deployment of 4G communication system, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called “beyond 4G network” or “post LTE system”.

Wireless communication is one of the most successful innovations in modern history. Recently, a number of subscribers of wireless communication services has exceeded 5 billion, and it continues growing rapidly. With the increasing popularity of smart phones and other mobile data devices (such as tablet computers, notebook computers, netbooks, e-book readers and machine-type devices) in consumers and enterprises, a demand for wireless data services is growing rapidly. In order to meet rapid growth of mobile data services and support new applications and deployments, it is very important to improve efficiency and coverage of wireless interfaces.

In order to improve the throughput of user data transmission, a user equipment may need to establish dual-connectivity, that is, to connect with two different base stations or different distributed units, so that the two base stations or distributed units can serve the user. In the process of establishing dual-connectivity, interruption of data transmission may occur, which will affect the performance of the user.

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.

The term “include” or “may include” refers to the existence of a corresponding disclosed function, operation or component which can be used in various embodiments of the present disclosure and does not limit one or more additional functions, operations, or components. The terms such as “include” and/or “have” may be construed to denote a certain characteristic, number, step, operation, constituent element, component or a combination thereof, but may not be construed to exclude the existence of or a possibility of addition of one or more other characteristics, numbers, steps, operations, constituent elements, components or combinations thereof.

The term “or” used in various embodiments of the present disclosure includes any or all of combinations of listed words. For example, the expression “A or B” may include A, may include B, or may include both A and B.

Unless defined differently, all terms used herein, which include technical terminologies or scientific terminologies, have the same meaning as that understood by a person skilled in the art to which the present disclosure belongs. Such terms as those defined in a generally used dictionary are to be interpreted to have the meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted to have ideal or excessively formal meanings unless clearly defined in the present disclosure.

Figures discussed below and various embodiments for describing the principles of the present disclosure in this patent document are only for illustration and should not be interpreted as limiting the scope of the present disclosure in any way. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any suitably arranged system or device.

FIGURE 1 is an exemplary system architecture 100 of system architecture evolution (SAE). User equipment (UE) 101 is a terminal device for receiving data. An evolved universal terrestrial radio access network (E-UTRAN) 102 is a radio access network, which includes a macro base station (eNodeB/NodeB) that provides UE with interfaces to access the radio network. A mobility management entity (MME) 103 is responsible for managing mobility context, session context and security information of the UE. A serving gateway (SGW) 104 mainly provides functions of user plane, and the MME 103 and the SGW 104 may be in the same physical entity. A packet data network gateway (PGW) 105 is responsible for functions of charging, lawful interception, etc., and may be in the same physical entity as the SGW 104. A policy and charging rules function entity (PCRF) 106 provides quality of service (QoS) policies and charging criteria. A general packet radio service support node (SGSN) 108 is a network node device that provides routing for data transmission in a universal mobile telecommunications system (UMTS). A home subscriber server (HSS)109 is a home subsystem of the UE, and is responsible for protecting user information including a current location of the user equipment, an address of a serving node, user security information, and packet data context of the user equipment, etc.

FIGURE 2 is an exemplary system architecture 200 according to various embodiments of the present disclosure. Other embodiments of the system architecture 200 can be used without departing from the scope of the present disclosure.

User equipment (UE) 201 is a terminal device for receiving data. A next generation radio access network (NG-RAN) 202 is a radio access network, which includes a base station (a gNB or an eNB connected to 5G core network 5GC, and the eNB connected to the 5GC is also called ng-eNB) that provides UE with interfaces to access the radio network. An access control and mobility management function entity (AMF) 203 is responsible for managing mobility context and security information of the UE. A user plane function entity (UPF) 204 mainly provides functions of user plane. A session management function entity SMF 205 is responsible for session management. A data network (DN) 206 includes, for example, services of operators, access of Internet and service of third parties.

Exemplary embodiments of the present disclosure are further described below with reference to the accompanying drawings.

The text and drawings are provided as examples only to help understand the present disclosure. They should not be interpreted as limiting the scope of the present disclosure in any way. Although certain embodiments and examples have been provided, based on the disclosure herein, it will be apparent to those skilled in the art that changes may be made to the illustrated embodiments and examples without departing from the scope of the present disclosure.

Before introducing the specific content, some assumptions and some definitions of the present disclosure are given below.

- Message names in the present disclosure are just examples, and other message names may be used.

- The term “first” and “second” included in the message names of the present disclosure are only examples of messages and do not represent an execution order.

- Detailed descriptions of steps irrelevant to the present disclosure are omitted in the present disclosure.

- In the present disclosure, the steps in each process can be combined with each other or performed independently. The execution steps of each process are only examples, and other possible execution orders are not excluded.

- In the present disclosure, a base station may be a 6G base station, a 5G base station (such as gNB and ng-eNB), a 4G base station (such as eNB), or other types of access nodes.

- In the present disclosure, when a cell accessed by the user equipment changes from one to another, this behavior may be called handover or Cell switch. In the following description, handover and cell switch have the same meaning.

- In the present disclosure, users, user equipment, user terminals and user terminal equipment are equivalent.

- In the present disclosure, synchronization information includes at least one of the following:

-- downlink synchronization information; and

-- uplink synchronization information, such as timing advance (TA) information.

Nodes involved in the present disclosure may include one or more of the following:

- a first node: user terminal equipment, which may be a mobile phone or a relay node;

- a second node: a centralized unit (CU) of a base station, or a control plane part of a centralized unit of a base station, or a base station. In an example, the base station may be a source base station or a source master base station during the movement of a user terminal. In another example, the base station may be a secondary base station of the user terminal, and the base station may be a target base station during the movement of the user terminal; and

- a third node: a distributed unit (DU) of a base station, which may be the distributed unit where a source cell is located during the movement of the user terminal, where the source cell is a special cell (SpCell). In an example, the special cell may be an SpCell of an MCG (master cell group) or a primary cell (PCell). In another example, the special cell may be an SpCell of an SCG (secondary cell group)) or a primary secondary cell group (SCG) cell (PSCell).

Cells involved in the present disclosure may be of at least one of the following cell types:

- Special cell (SpCell);

- Primary cell (PCell) or SpCell of a master cell group;

- Primary Secondary cell (PSCell), or primary cell of a secondary cell group, or SpCell of a secondary cell group; and

- SCell (secondary cell).

Base stations involved in the above-mentioned first/second/third/fourth/fifth nodes may be of one of the following types (other types that can be used for user terminal access are not excluded):

- Long Term Evolution (LTE) base station;

- 5G base station;

- 6G base station;

- Non-terrestrial network (NTN) base station;

- High Altitude Platform Station (HAPS) base station;

- Drone base station; and

- WIFI access point.

In the process of establishing dual-connectivity, or reconfiguring the dual-connectivity after establishing the dual-connectivity, a user will need to access a new cell (such as a primary cell (PCell) or a primary secondary cell (PSCell). In this process, the user may experience interruption or delay in data transmission. In order to realize a fast dual-connectivity establishment for the user equipment, how to reduce this interruption or delay is an urgent problem to be solved.

The numbers of the following steps do not represent the order in which the steps are performed, and the following steps can be performed independently or in combination with each other.

In order to help a user node configure dual-connectivity, the network side needs to configure the user equipment. The configuration may include the following steps, as shown in FIGURE 3:

Step 3-1: a second node transmits a first configuration request message to a third node, which may be used for at least one of the following or at least includes information for one of the following: 1) configuring at least one candidate cell (such as a Special cell of the SCG (PSCell)) of a secondary base station that the first node needs to access, and 2) managing resources for the first node to access the at least one candidate cell of the secondary base station. In an example, a first configuration request message (for example, it may be referred to as a first message) may be used to request configuration of a candidate first cell for the first node and/or a second cell associated with the candidate first cell. The first configuration request message may include at least one of the following:

- User identification information, which is used for indicating or identify the first node, that is, the first node directed to by the “first configuration request message” mentioned above.

- Identification information of a configured cell, such as SpCell ID, PCell ID, PSCell ID, etc. In an example, the configured cell may be a candidate cell (such as a candidate PSCell) on the secondary base station serving the first node, and this cell would become a candidate PSCell that the first node can select when establishing dual-connectivity. Specifically, the configured cell may be a candidate cell selected when performing conditional PSCell addition (CPA)/conditional PSCell change (CPC). In another example, the configured cell may be a cell (such as a PSCell) for serving the first node on the secondary base station of the first node, which may be a cell where the secondary base station serves the first node after the first node establishes dual-connectivity. Specifically, the configured cell may be a serving cell on the target secondary base station configured for the first node when performing a conditional handover with SCG (CHO with SCG). That is, once the first node accesses a candidate cell (PCell) of the CHO, the secondary base station serving the first node will serve the configured cell as a PSCell for serving the first node.

- Indication information associated with a configuration request, which may be used for indicating a configuration (such as user, primary cell, primary cell configuration, etc.) associated with the first configuration request message described above. For different cells or different user identifications, the indication information associated with a configuration request may be different, so multiple pieces of indication information associated with a configuration request may be contained. For a piece of indication information associated with a configuration request, it may include at least one of the following:

-- First association identification information, such as transaction ID, association ID, etc. In an example, this information may be generated by the second node. In another example, this information may be generated by another network node and transmitted to the second node by the other network node (such as a target MN).

-- Identification information of a first associated primary cell (first associated PCell ID), which may also be called first identification information of an associated first cell. This information may indicate a primary cell (such as PCell) of an associated primary base station. In an example, this information may indicate the identification of a PCell associated with the PSCell identified by the above-mentioned “identification information of a configured cell”. After receiving this information, a behavior of the third node may be to determine the PCell associated with the PSCell indicated by the above-mentioned “identification information of a configured cell”, so as to generate different SCG configurations associated with the PSCell according to the received different “identification information of a first associated primary cell” and determine the PCell associated with each generated SCG configuration. In an example, if the second node and the third node respectively belong to a centralized unit and a distributed unit of a target secondary base station in a process of CHO with SCG for the first node, the third node will generate different SCG configurations for different PCells according to the “identification information of a first associated primary cell” (the different SCG configurations may be for the same PSCell indicated by the above-mentioned “identification information of a configured cell”). Further, the “identification information of a first associated primary cell” is transmitted by another node to the second node, for example, transmitted by the target MN to the second node through a SN addition request message in the process of CHO with SCG.

-- Identification information of a first associated user (first associated UE ID), which may also be called first identification information of an associated first node. This information may indicate a user identification associated with the above-mentioned first configuration request message. In an example, the associated user identification information is identification information used by the first node in other processes on an interface between the second node and the third node. For example, if the second node and the third node are a centralized unit and a distributed unit of a base station respectively, the interface between the second node and the third node is an F1 interface, on which a plurality of different processes (such as a process of UE context setup) may be initiated for the first node. Each process will generate an identification for this user, and the above-mentioned “associated user identification information” may indicate an identification used for the first node in other processes (different from the process initiated in Step 3-1), such as CU F1AP UE ID and/or DU F1AP UE ID. In another example, the associated user identification information is the identification information of the first node on other network interfaces (such as other interfaces different from those between the second node and the third node). For example, if the second node and the third node are a centralized unit and a distributed unit of a base station respectively, the interface between the second node and the third node is an F1 interface. The above-mentioned “associated user identification information” may indicate identification information of the first node on an interface between the second node and another node (such as a fourth node, a master base station, a target master base station, etc.), such as SN XnAP UE ID (for example, in the process of CHO with SCG, the second node belongs to a target SN, and this ID is the identification information of the UE on the second node side) and/or source MN XnAP ID (for example, in the process of CHO with SCG, this ID is the ID of the UE on the source MN side) and/or target MN XnAP ID (for example, in the process of CHO with SCG, this ID is the ID of the UE on the target MN side). Further, in order to indicate other nodes, the above-mentioned “associated user identification information” may also include identification information of other nodes (such as MN ID, source MN ID, target MN ID, etc.). In another example, the associated user identification information may be a common identification information of the first node, such as the identification information used for the first node in different entities of the same base station (such as RAN UE ID) and the globally unified identification of the first node (such as IMSI, T-MISI, etc.).

-- Indication information of a first associated configuration, which may indicate the configuration associated with the above-mentioned “first association identification information” and/or the above-mentioned “identification information of a first associated primary cell” and/or “first associated user identification information”, such as configuration of MCG (such as configuration of CGConfigInfo), configuration of MCG+SCG (such as configuration in RRCReconfiguration) and configuration of SCG (such as configuration in CGConfig). The configuration may include at least one of the configuration of Service Data Adaptation Protocol (SDAP), the configuration of Packet Data Convergence Protocol (PDCP), the configuration of Radio Link Control (RLC), the configuration of logical channel, the configuration of Media Access Control (MAC) layer, physical layer configuration and cell configuration. In an example, the configuration indicated by the indication information is the configuration of the first node in the PCell (or the configuration of the MCG corresponding to the PCell). In another example, the configuration indicated by the indication information is the configuration of the first node (including the configuration of PCell and/or other PSCells, such as the configuration of MCG+SCG). When multiple pieces of the above-mentioned “indication information associated with a configuration request” are contained, the above-mentioned “first configuration request message” may contain multiple associated configurations.

-- Trigger indication information, which may indicate the reason for triggering the above-mentioned “first configuration request message”. For example, the reason for triggering is to newly generate a configuration, or to replace an existing configuration, or to delete an existing configuration. In an example, the trigger indication information may be “CHO trigger”, and the indicated trigger reason may be CHO initiation (the third node needs to generate a new configuration), CHO replace (the third node needs to replace the existing configuration), and CHO cancel (the third node needs to delete the existing configuration). After receiving this information, the third node can make correct configuration to avoid the waste of resources.

The above-mentioned “indication information associated with a configuration request” has different uses in different scenarios, which leads to different behaviors of the third node:

a. Scenario 1: the above-mentioned “indication information associated with a configuration request” is used to associate different processes (such as different processes performed in parallel) of the second node and the third node. If these different processes all contain the same “indication information associated with a configuration request”, then these processes are associated with the same cell (e.g. PCell, PSCell) or the same process (e.g. a process between the second node and an other node) or the same user or the same configuration. After receiving this information, the third node can optimize the resource allocation to avoid allocating different resources for the same cell/process/user/configuration, thus improving the resource utilization efficiency of the third node. In this scenario, the above-mentioned “indication information associated with a configuration request” has the beneficial effects of avoiding the repeated resource allocation by the third node for the first node and saving the resources of the third node.

b. Scenario 2: the above-mentioned “indication information associated with a configuration request” is used for indicating that different processes between the second node and the third node (in an example, the processes may be different processes for the same user/cell/configuration. Further, these processes may be processes performed in parallel) are directed to different cells or different processes (such as different processes between the second node and other nodes, in an example, in the CHO with SCG, the second node is the CU of SN, and another node is the target MN, and these different processes are different SN addition processes) or different users or different configurations. After receiving this information, the third node can generate respective configurations for different cells (or processes, users or configurations). Further, the third node may also add corresponding “indication information associated with a configuration response” in a subsequent first configuration response message (see Step 3-2) to help the second node know which cell/process/user/configuration the configuration contained in the first configuration response message is for. In this scenario, the above-mentioned “indication information associated with a configuration request” has the beneficial effects of helping the third node to associate different cells/processes/users/configurations to generate different configurations, ensuring that the third node can use a correct configuration to serve the first node, and improving the efficiency of resource utilization.

- Indication information for reconfiguration without synchronization, which may be used for indicating that the third node can generate a configuration (such as reconfiguration without synchronization) that does not need the first node to perform synchronization (such as uplink synchronization, downlink synchronization, uplink and downlink synchronization) when generating the configuration of the first node, thus when the first node accesses the cell indicated by the above-mentioned “identification information of a configured cell”, a synchronization process is not necessary. Or it can be used for indicating that when the first node accesses the cell (such as a second cell) indicated by the above-mentioned “identification information of a configured cell”, synchronization is not necessary. This information has the beneficial effects of reducing the processes when the first node accesses a cell and accelerating the access of the first node to the new cell. In addition to using the above-mentioned “indication information for reconfiguration without synchronization” for direct indication, the indication information can indicate that the third node can generate a configuration that does not need the first node to perform synchronization (such as uplink synchronization, downlink synchronization, uplink and downlink synchronization) when generating the configuration of the first node by including at least one of the following information:

-- Handover type indication information, which indicates that the handover type may be at least one of the following:

--- Handover based on RRC (Layer 3, L3) signaling;

--- Change of PCell of MCG based on RRC (Layer 3, L3) signaling;

--- Handover based on lower signaling (such as Layer 1/Layer 2, L1/L2);

--- Change of PCell based on lower signaling (such as Layer 1/Layer 2, L1/L2);

--- LTM (L1/L2 triggered mobility);

--- LTM of MCG.

-- Configuration identification information, which identifies the configuration of a handover performed by the first node, it may be for example, a configuration ID, a candidate ID, etc.

-- Identification information of a candidate cell for handover, which identifies a candidate PCell when the user performs handover.

- Indication information of an accessed cell, which may indicate the identification information of the third cell (e.g., PCell) accessed by the first node. In some implementations, the third cell may be one of candidate first cells of the first node. In an example, when the first node is configured with a CHO with SCG, the information indicates the PCell accessed by the first node. After receiving this information, the third node can determine the configuration of the PSCell (configuration of SCG) corresponding to the accessed PCell, which has the beneficial effect of helping the third node to serve the first node with a correct configuration of SCG. In another example, this information can help the third node manage its allocated resources. Specifically, the third node can determine the PSCell serving the first node according to the information. If the PSCell is the PSCell currently accessed by the first node, the third node can release the random access resources (such as preamble, Random Access Channel (RACH) occasion, etc.) allocated to the first node for accessing the PSCell, which has the beneficial effect of reducing waste of resources. Optionally, this indication information may be identification information indicating the configuration associated with the third cell accessed by the first node, and the third node may also determine the configuration associated with the third cell according to the identification information.

- Second SCG configuration indication information, which may be used for indicating the related configuration of SCG configured for the first node. In an example, the third node is a distributed unit of the MCG serving the first node, and after receiving the indication information, the third node can indicate the configuration of SCG used by the first node when changing the PCell according to this information. The information has the beneficial effects of helping to determine the configuration used by the first node when accessing the PSCell, and reducing unnecessary resource waste. The information may include at least one of the following:

-- Configuration identification information, such as configuration ID, candidate ID, etc.

-- Indication information of a current serving cell, which may indicate the serving cell configured for the first node, and these cells may be the currently serving cells, and this information includes at least one of the following:

--- Identification information of a serving PCell, which may indicate the PCell currently serving the first node;

--- Identification information of a serving PSCell, which may indicate the PSCell currently serving the first node.

-- Indication information of a target serving cell, which may indicate the target serving cell configured for the first node, and includes at least one of the following:

--- Indication information of a target PSCell, which may indicate the ID of the PSCell configured for the first node;

--- Indication information of a target PCell, which may indicate the ID of the PCell configured for the first node. Further, in order to indicate the PCell corresponding to the configured PSCell, the PCell indicated by this information corresponds to the PSCell indicated by the above-mentioned “indication information of a configured PSCell”.

-- Indication information for performing synchronization, which may indicate whether the first node needs to perform synchronization processes (such as a random access process) when accessing the PSCell. In an example, if the newly accessed PSCell of the first node is the same as the current serving PSCell, the first node can skip the random access process. In another example, if the first node accesses at least one cell indicated by the above-mentioned “indication information of a target serving cell”, this information may indicate whether the synchronization process can be skipped. In another example, if the current serving cell of the first node is at least one cell indicated by the above-mentioned “indication information of a current serving cell”, this information may indicate whether the synchronization process can be skipped. In another example, if the current serving cell of the first node is at least one cell indicated by the above-mentioned “indication information of a current serving cell” and the first node accesses at least one cell indicated by the above-mentioned “indication information of a target serving cell”, this information may indicate whether the synchronization process can be skipped.

-- Indication information of uplink resources, which may indicate the uplink resources (such as UL grant) used by the first node after accessing the PSCell indicated by the above-mentioned “indication information of a configured PSCell”, in which the uplink resources can help the first node to transmit uplink data quickly and reduce the delay.

- MCG reference configuration, which may indicate the reference configuration of the MCG accessed by the first node. This configuration may include at least one of SDAP configuration, PDCP configuration, RLC configuration, logical channel configuration, MAC layer configuration, physical layer configuration and cell configuration. After receiving this information, the third node can generate the configuration of SCG according to this information.

- First SCG configuration indication information, which may indicate the configuration information required for LTM of SCG, or it may be used for indicating the configuration information required for the first node to access a secondary cell group. In an example, the third node receiving the indication information is of the MCG serving of the first node. In another example, the third node receiving the indication information is of the SCG serving the first node or of a candidate SCG. After receiving this information, the third node can use this information to trigger the first node to obtain the synchronization information of the PSCell in advance (such as downlink synchronization information, uplink synchronization information, etc.) and/or add SCG or PSCell. The information includes at least one of the following:

-- Identification information of a PSCell, which may indicate a candidate PSCell;

-- Identification information of SCG configuration, which may indicate the configuration of SCG corresponding to a candidate PSCell, such as SCG (LTM) configuration ID, SCG (LTM) candidate ID, etc.

-- Bearer related information, which may indicate the identification information of the bearer accepted by the SCG corresponding to the candidate PSCell;

-- Release indication information, which is used to indicate the third node to release resources related to the first node. In an example, when the third node is a node of the MCG serving the first node, the indication information indicates the release of the configuration related to SCG LTM that has been stored in the third node (for the description of this configuration, please refer to other information in the above-mentioned “configuration indication information of SCG LTM”). In another example, when the third node is a node of the SCG serving the first node or a candidate SCG, the indication information indicates to release the resources allocated by the third node for the first node to access the PSCell or candidate PSCell. In an implementation, the released resources are resources allocated to the first node for uplink synchronization (such as RACH resources, which are resources for contention-free random access (CFRA), or resources for contention-based random access (CBRA)). After releasing the resources, it means that the first node does not need to perform a random access process when accessing the PSCell, so the indication information can also indicate that the first node can skip the random access process. Further, the release may indicate a temporary release of resources, and the resources will continue to be reserved for the first node after the first node leaves the PSCell, so that the first node can continue to use them when accessing the PSCell in the future. The information has the advantages that the configuration information related to SCG LTM and the corresponding resources at the third node are released in time, and the efficiency of resource utilization is improved;

-- Configuration information of a measurement signal, which may indicate the configuration information used by the first node when measuring the candidate PSCell. After receiving this information, the third node can configure the measurement of the first node to the candidate PSCell, so as to avoid a conflict between the resources used by the first node for communication on the PCell and those used by the first node for measuring the PSCell, and improve the utilization efficiency of the resources of the PCell. The information may include at least one of the following:

--- First signal configuration identification information, which identifies a set of configurations of signals measured by the first node;

--- First indication information of a signal type, which may indicate the type of the signal measured by the first node, and the signal type indicated by this information can be one of downlink reference signal (such as cell reference signal (cell RS), tracking reference signal (tracking RS), channel state information reference signal (CSI-RS)) and downlink synchronization signal (such as synchronization signal block (SSB));

--- First resource information, which may indicate the resources used by the measured signal, and this information may include at least one of the following:

---- First frequency domain resource information, which may indicate the location of the signal in frequency domain. In an embodiment, the location can be indicated by a frequency point and a bandwidth. In another embodiment, the location can be indicated by an identification of frequency domain resources, such as identification of a range of frequency domain resources. In another embodiment, the location can be indicated by an identification of a frequency band, such as identification of a bandwidth part (BWP), identification of a sub-band. In another embodiment, the frequency domain resource can be determined by the configuration information of BWP. Further, the user equipment should be able to measure signals of non-serving cells (such as synchronization signal block (SSB)) within the configured BWP;

---- First time domain resource information, which may indicate the location of the signal in time domain. In order to indicate the location, the information may include at least one of the following:

----- Period;

----- Offset;

----- Number of the time unit (such as the number of the slot and the number of the symbol);

----- time duration;

----- Start time, which may indicate the time to start measuring the signal.

First cell timing information, which may indicate the offset of timing between different cells (such as the offset of system frame number), where the offset can be relative to the current serving cell of the user equipment;

---- First beam configuration information, which may indicate the beam needed for signal measurement, and this information may include at least one of the following: transmission configuration indicator (TCI) status indication information, beam identification information, precoding information of the receiving beam, precoding information of the transmitting beam, etc.

---- First sequence information, which may indicate the sequence used by the first node for signal measurement;

---- First valid time information, which may indicate the valid time of the configuration information contained in the above-mentioned “first signal information”. If the valid time is exceeded, these configuration information will no longer be valid, and the first node cannot use these configuration information to measure the signal.

---- Configuration information of SSB measurement timing configuration (SMTC), which gives the configuration information of SSB of a cell, such as period, offset, measurement duration, indication information of physical cell identity (PCI), location information of SSB, etc.

-- Configuration information for early uplink synchronization, which may indicate the configuration information required for the first node to obtain uplink synchronization information of the PSCell in advance. After receiving this information, the third node can trigger the first node to transmit a random access signal to the PSCell in advance, so that the network side can obtain the uplink synchronization information needed for accessing the PSCell in advance. The information includes at least one of the following:

--- Indication information of a random signal, which indicates a random access signal used by the first node when acquiring synchronization information of a candidate PSCell. In an example, the information is index information of the random access signal, such as a preamble index;

--- Indication information of random access resources, which is used to determine the resources (such as RACH occasion and/or beam) used for random access signals (such as a preamble signal) transmitted by the first node, and may include at least one of the following:

---- First associated signal indication information, which may indicate a signal associated with a resource of the transmitted random access signal. In an example, if the signal is a synchronization signal (such as a Synchronization Signal Block (SSB)), the indication information is an SSB (synchronization signal (SS)/physical broadcast channel (PBCH)) Index. In another example, if the signal is a channel state information-reference signal (CSI-RS), the indication information is a CSI-RS Index. Further, this information may also indicate the beam used by the first node when transmitting the random access signal;

---- First resource configuration information, which may indicate the configuration of resources for transmitting random access signals. In an example, the configuration of the resources is the configuration of RACH occasions and/or beams.

--- Carrier indication information, which is an indication of the carrier where the resource is located, such as an ordinary uplink carrier or a supplementary uplink carrier;

--- First offset information, which may indicate a time offset of the PCell and the candidate PSCell, such as a super frame number offset, a subframe offset, a slot offset, a reference signal time difference (RSTD), etc.

Step 3-2: Optionally, the third node transmits a first configuration response message to the second node (for example, a response message for the first message), which may be used for providing configuration information of the SCG serving the first node or a candidate SCG. The message may include at least one of the following:

- Indication information associated with a configuration response, which may indicate the first configuration request message associated with the first configuration response message or a configuration associated with the first configuration response message. This information may include at least one of the following:

-- Second association identification information, such as a requested Identity, which may be referred to the above-mentioned “first association identification information”;

-- Identification information of a second associated primary cell, which may also be referred to as second identification information of an associated first cell, such as a requested PCell ID, or a requested Cell ID. For details of this information, please refer to the above-mentioned “identification information of a first associated primary cell”.

-- Identification information of a second associated user, which may also be referred to as second identification information of an associated first node, such as a requested UE ID. For details of this information, please refer to the above-mentioned “identification information of a first associated user”.

In an example, the indication information associated with a configuration request and/or the indication information associated with a configuration response can be used to configure a second cell associated with the candidate first cell. The information contained in the above-mentioned “indication information associated with a configuration response” may be generated by the third node according to the “first association identification information”, the “identification information of a first associated primary cell” or the “identification information of a first associated user” contained in the “first configuration request message” associated with the “first configuration response message”. In an example, the above-mentioned “second association identification information” is associated with the “first association identification information” contained in the “first configuration request message”, or the above-mentioned “identification information of a second associated primary cell” is associated with the “identification information of a first associated primary cell” contained in the “first configuration request message”, or the above-mentioned “identification information of a second associated user” is associated with the “identification information of a first associated user” contained in the “first configuration request message”. After receiving this information, the second node can associate the “first configuration request message” associated with the “first configuration response message” and transmit other configurations (such as the following cell group configuration information) contained in the “first configuration response message” to other nodes. The above-mentioned “indication information associated with a configuration response” has the beneficial effects of helping the second node obtain a correct configuration information, and then configuring the first node with other nodes, so as to prevent the first node from using a wrong configuration to access the cell.

-- Cell group configuration information, such as CellGroupConfig, which may include at least one of RLC configuration, logical channel configuration, MAC layer configuration, physical layer configuration and cell configuration. In an example, the configuration information is generated based on the “indication information associated with a configuration request” contained in Step 3-1. In another example, if Step 3-1 includes “indication information for reconfiguration without synchronization”, the configuration information included in this step need not include configuration information for random access in the PSCell or the candidate PSCell.

-- Uplink synchronization configuration response indication information, which may include configuration information required for acquiring synchronization information of the PSCell before the first node accesses the PSCell. For details of the information contained in this information, please refer to the above-mentioned “configuration information for early uplink synchronization”.

Step 3-3: the second node transmits a first user configuration message to the first node, which can be used to configure the first node to perform a PCell switch. In an example, the message can be used to configure the first node to perform LTM-based cell handover. The message may include at least one of the following:

- Third SCG configuration indication information, which may indicate the configuration information required by the first node to change the PSCell (SCG) (or access the SCG), and information contained in this information may be referred to the above-mentioned “first SCG configuration indication information”;

- Synchronization configuration indication information, which may indicate configuration information related to synchronization required for the first node to access a cell. In an example, this information may indicate configuration information required for the first node to perform random access, and the information includes at least one of the following:

-- Indication information for performing synchronization, which may indicate whether the first node needs to perform synchronization (such as to perform a random access process). The information contained in this information may refer to the “indication information for performing synchronization” contained in the above-mentioned “second SCG configuration indication information”, and this information can also contain other information contained in the above-mentioned “second SCG configuration indication information”, so that the first node can determine whether synchronization needs to be performed in combination with the other information;

-- Configuration information for uplink synchronization, which may indicate the configuration information required for the first node to acquire uplink synchronization information of the PSCell. In an example, this information may indicate configuration information required for the first node to perform CFRA. In another example, this information may indicate configuration information required for the first node to perform CBRA. The configuration information contained in this information may refer to the above-mentioned “configuration information for early uplink synchronization”. In an example, the information contained in this information is reconfiguration with synchronization;

-- Configuration information for non-uplink synchronization, which may indicate the configuration (such as cell ID, C-RNTI, configuration information of uplink resources required for uplink data transmission, etc.) required by the first node when accessing the PSCell without acquiring uplink synchronization, such as reconfiguration without synchronization. The above-mentioned “configuration information of uplink resources required for uplink data transmission” may be uplink resources required for transmitting uplink data when the first node accesses the PSCell, so that accessing of the first node to the PSCell can be expedited.

Embodiment 1: process of CHO with SCG

A scenario targeted by this embodiment is that the network side configures CHO for a first node, and a target node will configure MCG and SCG for the first node, that is, configuration information for CHO generated by the target node will include configuration of MCG where a candidate PCell is located and configuration of SCG corresponding to the PCell. This embodiment includes the following nodes:

-- A first node: a user terminal;

-- A first network node: a centralized unit of a base station serving the SCG (or a control plane part of the centralized unit of the base station), such as a target SN-CU (or a target SN-CU-CP);

-- A second network node: a distributed unit of the base station serving the SCG, such as a target SN-DU;

-- A third network node: the base station (or centralized unit of the base station or control plane part of the centralized unit of the base station) serving the MCG where the candidate PCell is located, such as a target MN (or target MN-CU, or target MN-CU-CP);

-- A fourth network node: a base station (or centralized unit of the base station, or control plane part of the centralized unit of the base station) serving the source PCell of the first node, such as a source MN (or source MN-CU, source MN-CU-CP).

This embodiment may include the following process, as shown in FIGURE 4:

-- Step 4-1: the first network node transmits a message 4-1 to the second network node, which can be used to configure a SCG corresponding to the candidate PCell. For details of information contained in message 4-1, please refer to the first configuration request message in Step 3-1 above.

-- Step 4-2: the second network node transmits a message 4-2 to the first network node, which can be used to transmit a configuration of the SCG generated by the second node to the first network node. For details of information contained in message 4-2, please refer to the first configuration response message in Step 3-2 above.

Optionally, before Step 4-1, it may further include:

-- Step 4-0-1: a fourth network node transmits a message 4-0-1 to a third network node, which can be used to request to configure a candidate PCell and a target MCG corresponding to the candidate PCell for the first node. In an example, the message 4-0-1 may be a Handover request message;

-- Step 4-0-2: the third network node transmits a message 4-0-2 to the first network node, which can be used to request to configure a corresponding SCG for the candidate PCell of the first node. In an example, the message 4-0-2 may be a secondary node addition request (SN addition request) message.

Optionally, after Step 4-2, it may further include:

-- Step 4-3-1: the first network node transmits a message 4-3-1 to the third network node, which can be used to provide the configuration of SCG corresponding to the candidate PCell. In an example, the message 4-3-1 may be a SN addition request acknowledge message;

-- Step 4-3-2: the third network node transmits a message 4-3-2 to the fourth network node, which can be used to provide the configuration of MCG and SCG corresponding to the candidate PCell. In an example, the message 4-3-2 may be a Handover Request Acknowledge message.

In the above processes, a plurality of candidate PCells can be prepared in parallel for the first node, so a plurality of the above processes can be performed in parallel, which has the advantage of accelerating the preparation process of PCells. During the performing, the first network node will transmit a plurality of messages 4-1 to the second network node, where each message is initiated for a different candidate PCell. In an example, the plurality of messages 4-1 configure the same PSCell for the first node with respect to different candidate PCells. In another example, the plurality of messages 4-1 configure different PSCells for the first node with respect to different candidate PCells. In this case, the second network node needs to distinguish that each message 4-1 is for a different PCell, and then generate different SCG configurations for the first node, so that when the first node accesses a PCell, the second network node will serve the first node with the SCG configuration corresponding to the PCell. In order to achieve this goal, there are different methods as follows:

Method 1: avoid parallel processes

In this method, parallel steps are not performed between the first network node and the second network node(that is, (not) performing the above Steps 4-1 and 4-2 in parallel). Specifically, the first network node transmits a message 4-1 (such as a first message 4-1, which is with respect to a PCell) firstly, and then the first network node transmits a message 4-1 (such as a second message 4-1, which is with respect to another PCell) after receiving a message 4-2 fed back by the second network node, and so on. Only after receiving a configuration of a PSCell generated for one PCell, the first network node will start the step of acquring a SCG configuration for another PCell. In an example, the above-mentioned “not to perform parallel processes” is targeted for a specific scenario. For example, in the case of CHO with SCG, when the first network node (target SN-CU) selects the same PSCell for different candidate PCells to serve the SCG, the first network node does not perform parallel steps (but serial steps) to acquire the configuration of SCG associated with the same PSCell generated by the second network node for different PCells. For each Step 4-1, the message 4-1 (for details, please refer to the first configuration request message in Step 3-1 above) may contain the following information:

- User identification information, which identifies the first node, and each message 4-1 transmitted by the first network node contains the same “user identification information”. In an example, the second network node can determine that a plurality of received messages 4-1 are directed to the same first node according to the same “user identification information” contained in the plurality of messages 4-1.

- Identification information of a configured cell, which identifies the PSCell, and each message 4-1 transmitted by the first network node contains the same or different PSCell ID. In an example, for a CHO with SCG, the target SN may prepare the same or different PSCell.

- Indication information associated with a configuration request, which may include one or more pieces of “indication information of a first associated configuration”, which includes the configuration information of the MCG where one or more candidate PCell are located. Further, this information may also contain “trigger indication information”. In an example, if the “identification information of a configured cell” received by the second network node is the same as the “identification information of a configured cell” in another previous message 4-1, and the “trigger indication information” indicates the second network node to generate a new configuration, the second network node will generate another new SCG configuration for the same PSCell (the previously generated SCG configuration for the same PSCell will not be deleted.)

Optionally, in the subsequent Step 4-2, the message 4-2 may include at least one of the following information (see the above Step 3-2 for details):

- Indication information associated with a configuration response; and

- Cell group configuration information.

Method 2: perform one process for the same user, and allow multiple parallel steps

In this method, the first network node and the second network node will start one process for the same user, such as a process of UE context modification, but the first network node can transmit multiple request messages (such as UE context modification request messages) (i.e., message 4-1) to the second network node. For each Step 4-1, each message 4-1 may contain the following information (see the first configuration request message in the above Step 3-1 for a detailed description):

- Indication information associated with a configuration request. In an example, the “indication information associated with a configuration request” contained in messages 4-1 in different Steps 4-1 will be different. The information may include at least one of the following:

-- First association identification information, which may be used to indicate that the request in message 4-1 in Step 4-1 above is for a configuration indicated by the identification information. For example, in a process of CHO with SCG, the identification information can indicate a configuration of SCG requested for a PCell.

-- Identification information of a first associated primary cell, which may be used to indicate that the request in message 4-1 in Step 4-1 above is for a configuration of the PCell indicated by the identification information. For example, in a process of CHO with SCG, the identification information can indicate a configuration of SCG requested for a PCell.

-- Identification information of a first associated user, which may indicate user identification information of the first node on other interfaces. The identification information may indicate that the request in message 4-1 in Step 4-1 above is for a configuration of the user indicated by the identification information. For example, in a process of CHO with SCG, the identification information can indicate a configuration of SCG required by the PCell corresponding to a process identified by the identification information on an interface between the first network node and an other network node (such as the third network node).

-- Indication information of a first associated configuration.

-- Trigger indication information.

Optionally, in the subsequent Step 4-2, the message 4-2 (such as a UE context modification response message) may contain the following information (see the above Step 3-2 for details):

- Response information of an associated configuration, which may include the information in the indication information associated with a configuration request included in the above Step 4-1 corresponding thereto. Specifically, if the information contained in the indication information associated with a configuration response is the same as the indication information associated with a configuration request contained in a message 4-1 transmitted by the first network node, it means that the message 4-2 corresponds to the message 4-1 and is a response message for the message 4-1, so that the first network node can determine the configuration of the first node. In an example, for a process of CHO with SCG, the first network node can determine the configuration of SCG for a PCell (for example, cell group configuration information as described below), and optionally, feed it back to the third network node in the above Step 4-3-1.

- Cell group configuration information.

Method 3: perform different processes for the same user in parallel

In this method, the first network node and the second network node will start multiple processes for the same user, such as a process of UE context setup, and each process includes the above Step 4-1 and optional Step 4-2. For Step 4-1 in each process, each message 4-1 may contain the following information (for details, please refer to the first configuration request message in Step 3-1 above):

- User identification information, which identifies the first node, and each message 4-1 transmitted by the first network node contains the same or different “user identification information”.

- Indication information associated with a configuration request. The information may include at least one of the following:

-- First association identification information, messages 4-1 of different Steps 4-1 contain the same “first association identification information”, so that the second network node can associate a plurality of different Steps 4-1, and further optimize the resource allocation (such as avoiding repeated resource allocation for the same first node).

-- Identification information of a first associated user, messages 4-1 of different Steps 4-1 contain the same “identification information of a first associated user”, so that the second network node can associate a plurality of different Steps 4-1, and further optimize the resource allocation (such as avoiding repeated resource allocation for the same first node).

-- Indication information of a first associated configuration.

-- Trigger indication information.

Optionally, in the subsequent Step 4-2, the message 4-2 (such as a UE context setup response message) may contain the following information (see the above Step 3-2 for details):

- Response information of an associated configuration;

- Cell group configuration information.

Embodiment 2: LTM with SCG (Secondary Cell Group)

In this embodiment, when the network side configures a candidate cell (PCell) for LTM handover for the user, the PSCell (or SCG) serving the user equipment can be kept unchanged. In order to avoid the interruption of communication on the PSCell (or SCG) during the change of the user's PCell, the configuration of the user's SCG can be optimized. This embodiment includes the following nodes:

- A first node: a user terminal;

- A first network node: a centralized unit of a base station serving the SCG (or a control plane part of the centralized unit of the base station), such as a target SN-CU (or a target SN-CU-CP);

- A second network node: a distributed unit of the base station serving the SCG, such as a target SN-DU;

- A third network node: the base station (or centralized unit of the base station or control plane part of the centralized unit of the base station) serving the MCG where the candidate PCell is located, such as a target MN (or target MN-CU, or target MN-CU-CP);

- A fifth network node: a distributed unit of the base station serving the MCG where a candidate PCell is located;

- A sixth network node: a distributed unit of the base station currently serving the first node (such as the distributed unit of the PCell serving the first node), such as a source DU;

- A seventh network node: a base station currently serving the first node, or a centralized unit of the base station or a control plane part of the centralized unit (such as the centralized unit of the PCell serving the first node), such as a source CU.

In an example, the above first network node and third network node may be the same node or different nodes. The above first network node and seventh network node may be the same node or different nodes.

This embodiment may include the following process, as shown in FIGURE 5:

- Step 5-1: the first network node transmits a message 5-1 to the second network node, which can be used to configure SCG serving the first node. For details of information contained in message 5-1, please refer to the first configuration request message in Step 3-1 above.

- Step 5-2: the second network node transmits a message 5-2 to the first network node, which can be used to transmit the configuration of SCG generated by the second node to the first network node. For details of information contained in message 5-2, please refer to the first configuration response message in Step 3-2 above.

Optionally, at least one of the following processes may be included before Step 5-1:

- the first network node and the fifth network node performs a preparation process of the MCG where the candidate PCell is located, which is targeted for a scenario that the MCG where the candidate PCell is located and the SCG of the first node are at different distributed units of the same base station;

- the third network node and the fifth network node performs a preparation process of the MCG where the candidate PCell is located and a process of addition or modification of SCG configuration between the third network node and the first network node, which are targeted for a scenario that the MCG where the candidate PCell is located and the SCG of the first node are at different base stations.

Optionally, after Step 5-2, the following process may be included:

- the network side triggers the first node to perform a PCell switch. In an example, the sixth network node can trigger the same, and in another example, the seventh network node can trigger the same.

Further, optionally, it can also include the following steps:

- Step 5-3: the first network node transmits a message 5-3 to the second network node, and details of the information contained in this message can be referred to the first configuration request message in the above Step 3-1. The function of this message can be to inform the second network node of the PCell accessed by the user, so as to help the second network node determine the configuration information of the SCG serving the first node.

In a process of configuring LTM with SCG, the network side needs to generate an appropriate configuration for the first node. On the one hand, it can reduce the interruption of data transmission of the first node in the process of LTM with SCG, and on the other hand, it can avoid the waste of network side resources. In order to achieve the above beneficial effects, examples of information contained in each message in the above process are as follows:

- message 5-1 may contain the following information:

-- User identification information;

-- Identification information of a configured cell;

-- Indication information associated with a configuration request;

-- Indication information for reconfiguration without synchronization. In a process of LTM with SCG, when the user switches the PCell through LTM, the PSCell can continue to be used for data transmission, so the first node does not need to re-access a PSCell after the PCell is switched. The function of this information may be to indicate the second network node to generate configuration without synchronization. For a detailed description of this information, please refer to the description in Step 3-1 above.

In the above information, for the descriptions of “user identification information”, “identification information of a configured cell” and “indication information associated with a configuration request”, in addition to the descriptions in Step 3-1 above, it may also refer to the descriptions in the three methods in “Embodiment 1” above. The main function of these information can be to help the second network node prepare SCG configuration for different candidate PCells.

- The message 5-2 may contain at least one of the following information (see Step 3-2 above for details):

-- Indication information associated with a configuration response. The description of this information can refer not only to the descriptions in Step 3-1 above, but also to the descriptions in the three methods in “Embodiment 1” above.

-- Cell group configuration information.

- The message 5-3 may contain the following information (see Step 3-1 above for details):

-- Indication information of an accessed cell.

Embodiment 3: continuous/subsequent MCG LTM with SCG

In this embodiment, when the network side configures a candidate cell (PCell) for LTM handover for a user, it also configures a PSCell corresponding to the candidate PCell and an SCG corresponding to the PSCell for the user. If the configured PSCell is not the current PSCell serving the user, resources for random access (such as resources for CFRA) will be configured for the user when configuring the SCG. When the user receives an indication to perform a PCell switch, it will also perform a random access process for accessing the PCell according to the configured resources. This embodiment involves the following nodes:

- A first node: a user terminal;

In an example, the first network node and the seventh network node may be the same node or different nodes.

In this embodiment, when configuring a user, the same PSCell (SCG) may be configured for different candidate PCells, and this same PSCell is not the PSCell currently accessed by the user. Therefore, when configuring a PSCell, the network will configure random access resources for the user to access the PSCell. When the user accesses a candidate PCell, it will access the PSCell according to the configured random access resources. However, after accessing the PSCell, when the user changes the PCell again, if the newly accessed PCell still corresponds to this PSCell, the user does not need to perform a random access process in the PSCell according to the configuration information. In order to avoid an unnecessary random access process and save network resources, this embodiment includes the following methods:

Method 1: the user determines whether a random access process is needed autonomously.

This method may include the following steps, as shown in FIGURE 6:

- Step 6-1: the sixth network node or the seventh network node transmits a message 6-1 to the first node, which may be used to indicate the change of the PCell, and the message contains at least one of the ID of a target PCell, the ID of a configuration corresponding to the target PCell, and timing advance information (such as TA required for accessing the target cell). After receiving the message, the first node accesses the target PCell;

- Step 6-2: the first node accesses the PSCell corresponding to the target PCell. The first node will access the PSCell according to its previously received configuration information for accessing the PSCell. If the PSCell is the PSCell currently serving the first node, and/or the configuration information for accessing the PSCell contains configuration information for performing random access, the first node can skip the process of random access and directly perform data transmission on the PSCell.

Method 2: the user determines whether a random access process is needed based on the pre-configuration of the network.

When configuring a candidate PCell for the first node, if the configuration of a corresponding PSCell (SCG) is also included, the network will indicate whether the random access process accessing the PSCell can be skipped. The method may include the following process, as shown in FIGURE 7:

- Step 7-1: the seventh network node transmits a message 7-1 to the first node, the contents of which can be referred to the first user configuration message in Step 3-3;

- Step 7-2: the sixth network node or the seventh network node transmits a message 7-2 to the first node, which may be used to indicate the change of the PCell, and the message contains at least one of the ID of a target PCell, the ID of a configuration corresponding to the target PCell, and timing advance information (such as TA required for accessing the target cell). After receiving the message, the first node accesses the target PCell;

- Step 7-3: the first node accesses the PSCell corresponding to the target PSCell. The first node will determine whether it is necessary to perform a random access process on the PSCell according to the information received in Step 7-1:

-- In an example, the first node determines whether a random access process is needed according to the “indication information for performing synchronization” contained in the message 7-1. For a detailed description, please refer to the description in the above Step 3-1 and/or Step 3-3. Further, if the first node determines that a random access process is needed, it can perform access according to the “configuration information for uplink synchronization” contained in the above message 7-1; and if the first node determines that the random access process is not needed, it can perform access according to the “configuration information for non-uplink synchronization” contained in the above message 7-1;

-- In an example, the first node determines whether it needs to perform a random access process autonomously. If the PSCell corresponding to the newly accessed PCell is the PSCell currently serving the first node, the first node may not perform the configuration information required for random access contained in the above message 7-1, or the first node may perform access according to the “configuration information for non-uplink synchronization” contained in the above message 7-1. If the first node determines that a random access process is needed, the first node can perform access according to the “configuration information for uplink synchronization” contained in the above message 7-1.

Method 3: determine whether a random access process is needed based on an handover indication of the network

This method is to indicate whether the first node needs to perform a random access process when indicating the user to perform a PCell switch. The method may include the following process, as shown in FIGURE 8:

- Step 8-1: the seventh network node transmits a message 8-1 to the sixth network node, which is used to configure the configuration information required by the first node to perform a PCell switch. The information contained in this message may refer to the first configuration request message in the above Step 3-1. Specifically, the message may include the above-mentioned “second SCG configuration indication information”, and the sixth network node may determine whether the first node needs to perform a random access process when accessing the PSCell according to this information;

- Step 8-2: the sixth network node or the seventh network node transmits a message 8-2 to the first node, which may be used to indicate the change of the PCell, and the message contains at least one of the ID of a target PCell, the ID of the configuration corresponding to the target PCell, and timing advance information (such as TA required for accessing the target cell). After receiving the message, the first node accesses the target PCell. Further, the message 8-2 may also include indication information on whether a random access process needs to be performed when accessing the PSCell. Before this step, the sixth network node or the seventh network node can determine whether the first node needs to perform a random access process when accessing the PSCell according to the configuration in the above Step 8-1.

Further, after the first node accesses the PSCell, optionally, it may further include the following steps:

- Step 8-3: the first network node transmits a message 8-3 to the second network node, which may be used to indicate the PSCell accessed by the first node, and the information contained in this message may refer to the first configuration request message in Step 3-1. Specifically, the message may contain “indication information of an accessed cell”, and the second network node can determine the PSCell serving the first node according to this information, and then determine whether it is necessary to release the random access resources needed by the first node when accessing the PSCell.

When the first network node and the seventh network node are different nodes, before Step 8-3, it may further include that the seventh network node transmits a first notification message to the first network node, which includes the identification information of the PCell accessed by the first node.

Embodiment 3: LTM-based SCG addition

In this embodiment, the network side configures SCG for a user, and triggers the user to add SCG by transmitting an LTM instruction to the user. This embodiment involves the following nodes:

- A first node: a user terminal;

This embodiment may include the following process, as shown in FIGURE 9:

- Step 9-1: the first network node transmits a message 9-1 to the second network node, which is used to prepare a PSCell serving the first node. The information contained in this message may refer to the first configuration request message in the above Step 3-1. Specifically, the message may contain at least one of the following information:

-- User identification information;

-- Identification information of a configured cell;

-- MCG reference configuration;

-- First SCG configuration indication information;

-- Indication information of uplink synchronization configuration request, which is used to request the second network node to provide configuration information required for acquiring synchronization information of the PSCell before the first node accesses the PSCell.

- Step 9-2: the second network node transmits a message 9-2 to the first network node, which is used for providing the configuration information required for the first node to access the PSCell. For details of the information contained in this message, please refer to the above first configuration response message. Specifically, the message may include the above-mentioned “uplink synchronization configuration response indication information”;

- Step 9-3: the seventh network node transmits a message 9-3 to the sixth network node, which is used for providing the servicing node of the first node with the configuration information required for the first node to access the PSCell, so as to help the sixth network node trigger the first node to add the PSCell. For details of information contained in this message, please refer to the above-mentioned first configuration request message. Specifically, the message may contain at least one of the following information:

-- User identification information;

-- Identification information of a configured cell;

-- MCG reference configuration;

-- First SCG configuration indication information.

When the seventh network node is different from the first network node, it also includes a second notification message transmitted by the first network node to the seventh network node, which may be used to provide the seventh network node with the configuration information required for the first node to access the PSCell.

- Step 9-4: the sixth network node transmits a message 9-4 to the seventh network node, which is used for providing configuration information of the MCG. For details of the information contained in this message, please refer to the first configuration response message in Step 3-2 above. Specifically, the message may contain the above-mentioned “cell group configuration information”.

- Step 9-5: the seventh network node transmits a message 9-5 to the first network node, which is used to configure the first node. For details of information contained in this message, please refer to the first user configuration message in Step 3-3 above.

- Step 9-6: the sixth network node transmits a message 9-6 to the first node, which is used to trigger the first node to add a PSCell. The message may contain at least one of the following information:

-- Indication information of addition of a PSCell;

-- Identification information of a PSCell; and

-- Identification information of configuration corresponding to the PSCell.

Configuration information of uplink resources of the PSCell, which may indicate the uplink resources used by the first node after accessing the PSCell, and the uplink resources can help the first node to quickly transmit uplink data and reduce the interruption of data transmission.

The present disclosure proposes to optimize the configuration of PSCells, reduce unnecessary waste of resources, and configure the user to quickly add PSCells when configuring different candidate primary cells (PCell) for the user.

It should be understood that the various embodiments, example aspects, methods, steps, processes, etc. shown above in conjunction with the drawings can be combined and implemented in any way, which is not limited herein.

Next, FIGURE 10 shows a flowchart of a method 1000 performed by a second node in a wireless communication system according to embodiments of the present disclosure.

As shown in FIGURE 10, a method 1000 performed by a second node in a wireless communication system according to embodiments of the present disclosure may include: in step S1001, transmitting a first message to a third node, wherein the first message is used for requesting to configure a candidate first cell for the first node and/or a second cell associated with the candidate first cell, wherein the first message includes indication information associated with a configuration request, which is used for indicating a configuration associated with the first message; and in step S1002, receiving a response message for the first message from the third node, wherein the response message is used for providing configuration information of a secondary cell group or a candidate secondary cell group serving the first node, and the response message includes indication information associated with a configuration response, and the indication information associated with a configuration response indicates a configuration associated with the response message.

According to embodiments of the present disclosure, the method 1000 may further include: transmitting a first user configuration message to the first node, wherein the first user configuration message includes information for configuring the first node to perform primary cell switch.

FIGURE 11 shows a flowchart of a method 1100 performed by a third node in a wireless communication system according to embodiments of the present disclosure.

As shown in FIGURE 11, the method 1100 performed by a third node in a wireless communication system according to embodiments of the present disclosure may include: in step S1101, receiving a first message from a second node, wherein the first message is used for requesting to configure a candidate first cell for the first node and/or a second cell associated with the candidate first cell, wherein the first message includes indication information associated with a configuration request, which is used for indicating a configuration associated with the first message; and in step S1102, transmitting a response message for the first message to the second node, wherein the response message is used for providing configuration information of a secondary cell group or a candidate secondary cell group serving the first node, and the response message includes indication information associated with a configuration response, and the indication information associated with a configuration response indicates a configuration associated with the response message.

In some implementations, the first cell may be a PSCell and the second cell may be a PCell. In other implementations, the first cell and the second cell may also be other cells.

It should be understood that the

methods

1000 and 1100 according to the embodiments of the present disclosure may further include one or more of the methods or steps as described above in connection with any embodiment, example, aspect or drawing, which are not repeated here.

Next, FIGURE 12 shows a schematic diagram of a node 1200 in a wireless communication system according to embodiments of the present disclosure.

As shown in FIGURE 12, a node 1200 (which may be the first node, the second node, the third node or any other network node as described above, for example) according to embodiments of the present disclosure may include a transceiver 1210 and a processor 1220. The transceiver 1210 may be configured to transmit and receive signals. The processor 1220 may be coupled to the transceiver 1210 and may be configured to (e.g., control the transceiver 1210 to) perform any method performed by a second node and/or a third node in a wireless communication system according to embodiments of the present disclosure.

Herein, a node can also be referred to as a node device. Herein, a processor can also be called a controller.

FIGURE 13 is a block diagram of an internal configuration of a UE, according to an embodiment.

As shown in FIGURE 13, the UE according to an embodiment may include a transceiver 1310, a memory 1320, and a processor 1330. The transceiver 1310, the memory 1320, and the processor 1330 of the UE may operate according to a communication method of the UE described above. However, the components of the UE are not limited thereto. For example, the UE may include more or fewer components than those described above. In addition, the processor 1330, the transceiver 1310, and the memory 1320 may be implemented as a single chip. Also, the processor 1330 may include at least one processor.

Furthermore, the UE of FIGURE 13 corresponds to the UE 201 of FIGURE 2.

The transceiver 1310 collectively refers to a UE receiver and a UE transmitter, and may transmit/receive a signal to/from a base station or a network entity. The signal transmitted or received to or from the base station or a network entity may include control information and data. The transceiver 1310 may include a RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and a RF receiver for amplifying low-noise and down-converting a frequency of a received signal. However, this is only an example of the transceiver 1310 and components of the transceiver 1310 are not limited to the RF transmitter and the RF receiver.

Also, the transceiver 1310 may receive and output, to the processor 1330, a signal through a wireless channel, and transmit a signal output from the processor 1330 through the wireless channel.

The memory 1320 may store a program and data required for operations of the UE. Also, the memory 1320 may store control information or data included in a signal obtained by the UE. The memory 1320 may be a storage medium, such as read-only memory (ROM), random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

The processor 1330 may control a series of processes such that the UE operates as described above. For example, the transceiver 1310 may receive a data signal including a control signal transmitted by the base station or the network entity, and the processor 1330 may determine a result of receiving the control signal and the data signal transmitted by the base station or the network entity.

FIGURE 14 is a block diagram of an internal configuration of a base station or a network entity, according to an embodiment.

As shown in FIGURE 14, the base station or the network entity according to an embodiment may include a transceiver 1410, a memory 1420, and a processor 1430. The transceiver 1410, the memory 1420, and the processor 1430 of the base station or the network entity may operate according to a communication method of the base station or the network entity described above. However, the components of the base station or the network entity are not limited thereto. For example, the base station or the network entity may include more or fewer components than those described above. In addition, the processor 1430, the transceiver 1410, and the memory 1420 may be implemented as a single chip. Also, the processor 1430 may include at least one processor.

Furthermore, the base station or the network entity of the FIGURE 14 corresponds to the base station included in the NG-RAN 202 of the FIGURE 2.

The transceiver 1410 collectively refers to the base station(or the network entity receiver) and a base station(or the network entity) transmitter, and may transmit/receive a signal to/from a terminal or a network entity or a base station. The signal transmitted or received to or from the terminal or a network entity or the base station may include control information and data. The transceiver 1410 may include a RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and a RF receiver for amplifying low-noise and down-converting a frequency of a received signal. However, this is only an example of the transceiver 1410 and components of the transceiver 1410 are not limited to the RF transmitter and the RF receiver.

Also, the transceiver 1410 may receive and output, to the processor 1430, a signal through a wireless channel, and transmit a signal output from the processor 1430 through the wireless channel.

The memory 1420 may store a program and data required for operations of the base station or the network entity. Also, the memory 1420 may store control information or data included in a signal obtained by the base station or the network entity. The memory 1420 may be a storage medium, such as read-only memory (ROM), random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

The processor 1430 may control a series of processes such that the base station or the network entity operates as described above. For example, the transceiver 1410 may receive a data signal including a control signal transmitted by the terminal or the network entity or the base station, and the processor 1430 may determine a result of receiving the control signal and the data signal transmitted by the terminal or the network entity or the base station.

Various embodiments of the present disclosure may be implemented as computer-readable codes embodied on a computer-readable recording medium from a specific perspective. A computer-readable recording medium is any data storage device that can store data readable by a computer system. Examples of computer-readable recording media may include read-only memory (ROM), random access memory (RAM), compact disk read-only memory (CD-ROM), magnetic tape, floppy disk, optical data storage device, carrier wave (e.g., data transmission via the Internet), etc. Computer-readable recording media can be distributed by computer systems connected via a network, and thus computer-readable codes can be stored and executed in a distributed manner. Furthermore, functional programs, codes and code segments for implementing various embodiments of the present disclosure can be easily explained by those skilled in the art to which the embodiments of the present disclosure are applied.

It will be understood that the embodiments of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software. The software may be stored as program instructions or computer-readable codes executable on a processor on a non-transitory computer-readable medium. Examples of non-transitory computer-readable recording media include magnetic storage media (such as ROM, floppy disk, hard disk, etc.) and optical recording media (such as CD-ROM, digital video disk (DVD), etc.). Non-transitory computer-readable recording media may also be distributed on computer systems coupled to a network, so that computer-readable codes are stored and executed in a distributed manner. The medium can be read by a computer, stored in a memory, and executed by a processor. Various embodiments may be implemented by a computer or a portable terminal including a controller and a memory, and the memory may be an example of a non-transitory computer-readable recording medium suitable for storing program (s) with instructions for implementing embodiments of the present disclosure. The present disclosure may be realized by a program with code for concretely implementing the apparatus and method described in the claims, which is stored in a machine (or computer)-readable storage medium. The program may be electronically carried on any medium, such as a communication signal transmitted via a wired or wireless connection, and the present disclosure suitably includes its equivalents.

What has been described above is only the specific implementation of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Anyone who is familiar with this technical field may make various changes or substitutions within the technical scope disclosed in the present disclosure, and these changes or substitutions should be covered within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

A method performed by a second node in a wireless communication system, including:

transmitting a first message, to a third node, wherein the first message is used for requesting to configure a candidate first cell for a first node and/or a second cell associated with the candidate first cell, wherein the first message includes indication information associated with a configuration request, which is used for indicating a configuration associated with the first message; and

receiving a response message for the first message, from the third node, wherein the response message is used for providing configuration information of a secondary cell group or a candidate secondary cell group serving the first node, and the response message includes indication information associated with a configuration response, and the indication information associated with the configuration response indicates a configuration associated with the response message.
The method of claim 1,

wherein the first message further includes at least one of the following:

indication information for reconfiguration without synchronization, which is used for indicating to the third node that synchronization is not required when the first node accesses the second cell;

indication information of an accessed cell, which is used for indicating a third cell accessed by the first node, wherein the third cell is one of candidate first cells; or

first secondary cell group configuration indication information, which is used for indicating configuration information required for the first node to access the secondary cell group.
The method of claim 1,

wherein the indication information associated with a configuration request and/or the indication information associated with a configuration response are used to configure the second cell associated with the candidate first cell, and

wherein the indication information associated with a configuration request and/or the indication information associated with a configuration response include at least one of the following:

association identification information, identification information of an associated first cell and identification information of an associated first node.
The method of claim 3,

wherein the identification information of the associated first node is identification information of the first node used on a second interface different from a first interface, and

wherein the first interface is an interface between the second node and the third node.
The method of claim 1, wherein the response message further includes at least one of the following:

cell group configuration information, which includes at least one of radio link control (RLC) configuration, logical channel configuration, media access control (MAC) layer configuration, physical layer configuration and cell configuration; and

uplink synchronization configuration response indication information, which includes configuration information required for acquiring synchronization information of the second cell before the first node accesses the second cell.
The method of claim 1, further including:

transmitting a first user configuration message, to the first node, wherein the first user configuration message includes information for configuring the first node to perform primary cell switch.
The method of claim 6, wherein the first user configuration message includes at least one of the following:

third secondary cell group configuration indication information, which is used for indicating configuration information required for the first node to access the secondary cell group; and

synchronization configuration indication information, which is used for indicating synchronization-related configuration information required for the first node to access the second cell.
A method performed by a third node in a wireless communication system, including:

receiving a first message, from a second node, wherein the first message is used for requesting to configure a candidate first cell for a first node and/or a second cell associated with the candidate first cell, wherein the first message includes indication information associated with a configuration request, which is used for indicating a configuration associated with the first message; and

transmitting a response message for the first message, to the second node, wherein the response message is used for providing configuration information of a secondary cell group or a candidate secondary cell group serving the first node, and the response message includes indication information associated with a configuration response, and the indication information associated with the configuration response indicates a configuration associated with the response message.
The method of claim 8, wherein the first message further includes at least one of the following:

indication information for reconfiguration without synchronization, which is used for indicating to the third node that synchronization is not required when the first node accesses the second cell;

indication information of an accessed cell, which is used for indicating a third cell accessed by the first node, wherein the third cell is one of candidate first cells; or

first secondary cell group configuration indication information, which is used for indicating configuration information required for the first node to access the secondary cell group.
The method of claim 8,

wherein the indication information associated with a configuration request and/or the indication information associated with a configuration response are used to configure the second cell associated with the candidate first cell, and

wherein the indication information associated with a configuration request and/or the indication information associated with a configuration response include at least one of the following:

association identification information, identification information of an associated first cell and identification information of an associated first node.
The method of claim 10,

wherein the identification information of the associated first node is identification information of the first node used on a second interface different from a first interface, and

wherein the first interface is an interface between the second node and the third node.
The method of claim 8, wherein the response message further includes at least one of the following:

cell group configuration information, which includes at least one of radio link control (RLC) configuration, logical channel configuration, media access control (MAC) layer configuration, physical layer configuration and cell configuration; and

uplink synchronization configuration response indication information, which includes configuration information required for acquiring synchronization information of the second cell before the first node accesses the second cell.
A second node, comprising:

a processor; and

a transceiver operably coupled to the processor, wherein the transceiver configured to:

transmit a first message to a third node, wherein the first message is used for requesting to configure at least one of a candidate first cell for a first node and/or a second cell associated with the candidate first cell, wherein the first message includes indication information associated with a configuration request, which is used for indicating a configuration associated with the first message; and

receive a response message for the first message, from the third node, wherein the response message is used for providing configuration information of a secondary cell group or a candidate secondary cell group serving the first node, and the response message includes indication information associated with a configuration response, and the indication information associated with the configuration response indicates a configuration associated with the response message.
The second node of claim 13,

wherein the first message further includes at least one of the following:

indication information for reconfiguration without synchronization, which is used for indicating to the third node that synchronization is not required when the first node accesses the second cell;

indication information of an accessed cell, which is used for indicating a third cell accessed by the first node, wherein the third cell is one of candidate first cells; or

first secondary cell group configuration indication information, which is used for indicating configuration information required for the first node to access the secondary cell group.
The second node of claim 13,

wherein the indication information associated with a configuration request and/or the indication information associated with a configuration response are used to configure the second cell associated with the candidate first cell, and

wherein the indication information associated with a configuration request and/or the indication information associated with a configuration response include at least one of the following:

association identification information, identification information of an associated first cell, or identification information of an associated first node.