CN116724601A

CN116724601A - Method and apparatus for managing remote terminal connection mode mobility through relay terminal in wireless communication system

Info

Publication number: CN116724601A
Application number: CN202280011041.3A
Authority: CN
Inventors: 姜贤贞; 阿尼尔·阿基瓦尔; 金成勳
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2021-01-20
Filing date: 2022-01-17
Publication date: 2023-09-08

Abstract

The present disclosure relates to: an IoT technology and a communication technology and system thereof that blend with a fifth generation (5G) or sixth generation (6G) or quasi-5G communication system, the 5G or 6G or quasi-5G communication system for supporting higher data transmission rates than a fourth generation (4G) communication system such as Long Term Evolution (LTE). The present disclosure is applicable to smart services based on 5G communication technology and IoT-related technology, such as smart homes, smart buildings, smart cities, smart or networked automobiles, healthcare, digital education, retail businesses, security and security-related services, and the like. According to various embodiments of the present disclosure, a method and apparatus for handling connection mode mobility of a terminal in a wireless communication system if the terminal can access a network through a direct connection with a base station or a connection with the base station through a sidelink relay are provided.

Description

Method and apparatus for managing remote terminal connection mode mobility through relay terminal in wireless communication system

Technical Field

The present disclosure relates to a wireless communication system. More particularly, the present disclosure relates to a method and apparatus for handling terminal connection mode mobility for establishing a connection to a base station based on a sidelink with a relay terminal in a wireless communication system.

Background

Fifth generation (5G) mobile communication technology defines a wide frequency band, making high transmission rates and new services possible, and can be implemented not only in a "sub 6GHz" frequency band such as 3.5GHz, but also in a "higher than 6GHz" frequency band called millimeter waves including 28GHz and 39 GHz. Further, it has been considered to implement a sixth generation (6G) mobile communication technology (referred to as a super 5G system) in a terahertz frequency band (e.g., 95GHz to 3THz frequency band) in order to achieve a transmission rate 50 times faster than that of the 5G mobile communication technology and an ultra-low delay of one tenth of that of the 5G mobile communication technology.

At the beginning of the development of 5G mobile communication technology, in order to support services and meet performance requirements related to enhanced mobile broadband (embbb), ultra-reliable low latency communication (URLLC), and mass machine type communication (mMTC), standardization regarding beamforming and mass Multiple Input Multiple Output (MIMO) has been performed to mitigate radio path loss in millimeter waves and increase radio wave transmission distances, support parameter sets for dynamic operation for effectively utilizing millimeter wave resources and slot formats (e.g., operating a plurality of subcarrier intervals), support initial access techniques for multi-beam transmission and broadband, definition and operation of bandwidth portion (BWP), new channel coding methods such as Low Density Parity Check (LDPC) codes for mass data transmission and polarity codes for highly reliable transmission of control information, L2 pre-processing and network slicing, and dedicated networks for providing dedicated services.

Currently, with respect to services supported by the 5G mobile communication technology, discussions about improvement and performance enhancement of the initial 5G mobile communication technology are underway, and physical layer standardization with respect to technologies such as the internet of vehicles (V2X), unlicensed new radios (NR-U) aimed at meeting various regulatory-related requirements in unlicensed bands, NR UE power saving, non-terrestrial network (NTN) as UE satellite direct communication providing coverage and positioning in an area where communication with a terrestrial network is impossible, have been made in order to help driving decisions of an autonomous vehicle based on information about the vehicle position and state transmitted by the vehicle, and to improve convenience of users.

Furthermore, air interface architecture/protocols have been standardized with respect to technologies such as industrial internet of things (UNT) supporting new services by interworking and convergence with other industries, integrated Access and Backhaul (IAB) for providing nodes for network service area extension by supporting wireless backhaul links and access links in an integrated manner, mobility enhancements including conditional handoffs and Dual Active Protocol Stack (DAPS) handoffs, and two-step random access (two-step RACH) for simplifying random access procedures. Standardization is also underway in relation to 5G baseline architecture (e.g., service-based architecture or service-based interface) for combining Network Function Virtualization (NFV) and Software Defined Network (SDN) technologies, and system architecture/services for receiving Mobile Edge Computing (MEC) of services based on UE location.

With commercialization of the 5G mobile communication system, networking devices that have grown exponentially will be connected to the communication network, and thus it is expected that enhanced functions and performance of the 5G mobile communication system and integrated operation of the networking devices will be necessary. To this end, new research related to augmented reality (XR) is scheduled by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metauniverse service support, and unmanned aerial vehicle communication to efficiently support Augmented Reality (AR), virtual Reality (VR), mixed Reality (MR), etc., 5G performance improvement, and complexity reduction.

Further, such development of the 5G mobile communication system will not only be the basis for developing new waveforms and multi-antenna transmission technologies for providing coverage in the terahertz band of the 6G mobile communication technology, such as full-dimensional MIMO (FD-MIMO), array antennas and massive antennas, metamaterial-based lenses and antennas for improving terahertz band signal coverage, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surfaces (RIS), but also full duplex technology for improving frequency efficiency of the 6G mobile communication technology and improving system network, AI-based communication technology for realizing system optimization and internalization of end-to-end AI support functions using satellites and AI from the design stage, and next generation distributed computing technology for realizing services with complexity exceeding the UE operation capability limit using ultra-high performance communication and computing resources.

Disclosure of Invention

[ technical problem ]

The present disclosure may provide a method and apparatus for handling mobility of a connection mode (RRC connected state) of a terminal in a wireless communication system when the terminal is connected to a base station through a sidelink relay or when the terminal is directly connected to the base station. In a general communication system in which a terminal is directly connected to a base station, connection mode mobility of the terminal can be supported as a handover procedure. In a sidelink relay system in which a terminal supports connection with a base station through sidelink relay, connection mode mobility of the terminal can be supported as a handover and path change procedure. The present disclosure may provide a method and apparatus for processing configuration information related to a sidelink relay in a wireless communication system, and a procedure of changing a terminal path in the following cases: when a terminal changes a sidelink relay within the same base station, when a terminal changes from being connected directly to a base station within the same base station through a sidelink relay connection, when a terminal changes from being connected directly to a sidelink relay connection within the same base station through a sidelink relay connection within the same base station, when a terminal changes a sidelink relay between different base stations, when a terminal changes from being connected directly to one base station to being connected directly to another base station, when a terminal changes from being connected directly to another base station through a sidelink relay connection of one base station, or when a terminal changes from being connected directly to one base station to being connected directly to another base station.

The technical problems to be solved by the present disclosure are not limited to the above technical problems, and other technical problems not mentioned herein will be clearly understood from the following description by those of ordinary skill in the art to which the present disclosure pertains.

Technical scheme

According to an embodiment of the present disclosure, a method performed by a terminal in a wireless communication system may include: receiving measurement configuration information for changing a path from a base station, the measurement configuration information including at least one of frequency information of at least one neighbor cell to be measured or resource information of at least one candidate sidelink relay terminal to be measured; performing measurements on at least one neighboring cell or at least one candidate sidelink relay terminal based on the measurement configuration information; and transmitting the measurement result to the base station.

Further, the resource information of the at least one candidate sidelink relay terminal may include a physical cell identifier PCI of a serving cell of the at least one candidate sidelink relay terminal.

Further, in case the measurement result includes the measurement result of at least one candidate sidelink relay terminal, the measurement result may include at least one of: the identification information of the at least one candidate sidelink relay terminal, the identification information of the serving cell of the at least one candidate sidelink relay terminal, or the measurement result value of the at least one candidate sidelink relay terminal.

Furthermore, the method may further comprise: receiving a message indicating handover or change of the sidelink relay terminal from the base station; releasing the PC5 radio resource control, RRC, connection with the service side link relay terminal in case the terminal is connected to the service side link relay terminal; and establishing a PC5 RRC connection with the target sidelink relay terminal in a case that the terminal is connected to the serving base station.

Further, according to an embodiment of the present disclosure, a method performed by a base station in a wireless communication system may include: transmitting measurement configuration information for changing a path to the terminal, the measurement configuration information including at least one of frequency information of at least one neighbor cell to be measured or resource information of at least one candidate sidelink relay terminal to be measured; receiving measurement results for at least one neighboring cell or at least one candidate sidelink relay terminal based on the measurement configuration information from the terminal; and determining to switch the terminal or connect the terminal to the target sidelink relay terminal based on the measurement result.

Furthermore, the method may further comprise: upon determining to connect the terminal to the target sidelink relay terminal based on the received measurement result, a message including the configuration information of the sidelink relay is transmitted to the target sidelink relay terminal, the message including at least one of identification information of the terminal, sidelink relay Uu configuration information, or sidelink relay radio link control RLC configuration information.

Further, according to an embodiment of the present disclosure, a terminal in a wireless communication system may include: a transceiver; and a controller coupled with the transceiver and configured to: receiving measurement configuration information for changing a path from a base station, the measurement configuration information including at least one of frequency information of at least one neighbor cell to be measured or resource information of at least one candidate sidelink relay terminal to be measured; performing measurements on at least one neighboring cell or at least one candidate sidelink relay terminal based on the measurement configuration information; and transmitting the measurement result to the base station.

Further, according to an embodiment of the present disclosure, a base station in a wireless communication system may include: a transceiver; and a controller coupled with the transceiver and configured to: transmitting measurement configuration information for changing a path to the terminal, the measurement configuration information including at least one of frequency information of at least one neighbor cell to be measured or resource information of at least one candidate sidelink relay terminal to be measured; receiving measurement results for the at least one neighboring cell or the at least one candidate sidelink relay terminal based on the measurement configuration information from the terminal; and determining to switch the terminal or connect the terminal to the target sidelink relay terminal based on the measurement result.

[ advantageous effects ]

According to embodiments of the present disclosure, an apparatus and method capable of efficiently providing a service and expanding a service coverage in a wireless communication system may be provided.

The effects obtainable in the present disclosure are not limited to the above-described effects, and other effects not mentioned are clearly understood by those skilled in the art from the following description.

Drawings

Fig. 1a is a diagram illustrating a wireless communication system according to an embodiment of the present disclosure.

Fig. 1b is a diagram illustrating a wireless communication system according to an embodiment of the present disclosure.

Fig. 2 is a diagram showing the construction of a base station in a wireless communication system according to an embodiment of the present disclosure.

Fig. 3 is a diagram illustrating a configuration of a UE in a wireless communication system according to an embodiment of the present disclosure.

Fig. 4 is a diagram showing the configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure.

Fig. 5 is a diagram illustrating a structure of time-frequency resources of a wireless communication system according to an embodiment of the present disclosure.

Fig. 6 is a diagram illustrating an operation sequence of a UE, a sidelink relay terminal, and a base station processing RRC connection establishment between the UE and the base station according to an embodiment of the present disclosure.

Fig. 7 is a diagram illustrating an operation sequence in which a UE processes connection mode mobility of the UE according to an embodiment of the present disclosure.

Fig. 8 is a diagram illustrating an operation sequence of a UE, a serving sidelink relay terminal, and a base station processing connection mode mobility of the UE according to an embodiment of the present disclosure.

Fig. 9 is a diagram illustrating an operation sequence of a UE, a serving sidelink relay terminal, and a base station processing connection mode mobility of the UE according to an embodiment of the present disclosure.

Fig. 10 is a diagram illustrating an operation sequence of a UE, a serving sidelink relay terminal, and a base station processing connection mode mobility of the UE according to another embodiment of the present disclosure.

Fig. 11a is a diagram illustrating an operation sequence of a service side link relay terminal and a base station to handle connection mode mobility of a UE according to an embodiment of the present disclosure.

Fig. 11b is a diagram illustrating an operation sequence of a serving sidelink relay terminal and a base station processing connection mode mobility of a UE according to another embodiment of the present disclosure.

Fig. 12a is a diagram illustrating a connection mode mobility operation sequence of a UE, a target sidelink relay terminal, and a base station processing UE according to an embodiment of the present disclosure.

Fig. 12b is a diagram illustrating a connection mode mobility operation sequence of a UE, a target sidelink relay terminal, and a base station processing UE according to another embodiment of the present disclosure.

Fig. 13 is a diagram illustrating an operation sequence in which a UE and a base station process connection mode mobility of the UE according to an embodiment of the present disclosure.

Fig. 14 is a diagram illustrating an operation sequence of a UE, a serving sidelink relay terminal, a serving base station, and a target base station to handle connection mode mobility of the UE according to an embodiment of the present disclosure.

Fig. 15 is a diagram illustrating an operation sequence of a UE, a serving sidelink relay terminal, a serving base station, and a target base station to handle connection mode mobility of the UE according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that in the drawings, like elements are denoted by like reference numerals as much as possible. Further, detailed descriptions of well-known functions and elements that may obscure the subject matter of the present disclosure will be omitted.

In describing the embodiments, descriptions of technical contents that are well known in the art to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to more clearly convey the subject matter of the present disclosure, and is not made ambiguous by omitting unnecessary descriptions.

For the same reasons, some elements are enlarged, omitted, or schematically shown in the drawings. Furthermore, the dimensions of each of the elements described do not fully reflect the actual dimensions. In the drawings, identical or corresponding elements are given the same reference numerals.

The advantages and features of the present disclosure and the manner in which they are achieved will become apparent from the embodiments described below with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. The present disclosure is limited only by the scope of the appended claims. Like numbers refer to like elements throughout.

It will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart block or blocks. These computer program instructions may also be stored in a computer-usable or computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-usable or computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

Furthermore, each block of the flowchart illustrations may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the block may occur out of the order. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

As used herein, the term "unit" refers to a software element or a hardware element, such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), that performs a predetermined function. However, the term "unit" does not always have a meaning limited to software or hardware. The "unit" may be configured to be stored in an addressable storage medium or to execute one or more processors. Thus, a "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided by the elements and units may be combined into the functions of a smaller number of elements and units or separated into the functions of a larger number of elements and units. Furthermore, the elements and units may be implemented as one or more Central Processing Units (CPUs) within an operating device or secure multimedia card.

Embodiments of the present disclosure will be described herein in terms of the 5G mobile communication standard specified by the third generation partnership project (3 GPP), which is a mobile communication standardization organization, focusing on a radio access network (i.e., new Radio (NR)) and a packet core (i.e., a 5G system, a 5G core network, or a Next Generation (NG) core). However, it will be apparent to those skilled in the art that the subject matter of the present disclosure may also be applied to other communication systems having similar technical backgrounds with slight modifications without departing from the scope of the present disclosure.

In a 5G system, a network data collection and analysis function (NWDAF) may be defined, which is a network function that collects, analyzes and provides data in a 5G network in order to support network automation. The NWDAF may collect information from the 5G network, store and analyze the collected information, and provide the analysis result to an unspecified Network Function (NF). The analysis results can be used independently in each NF.

For convenience of the following description, some terms and names defined in 3GPP standards (e.g., 5G, NR, LTE, or similar system standards) will be used. However, the present disclosure is not limited to these terms and names, and may also be applied to any other system that meets any other standard.

Hereinafter, the present disclosure relates to a method and apparatus for handling connection mode mobility of a terminal in a wireless communication system when the terminal is connected to a base station directly or through a sidelink relay. Specifically, the present disclosure provides the following solutions: when a terminal is connected to a base station through a sidelink relay or directly, determining whether to monitor and measure a sidelink, determining whether to monitor and measure a Uu link, determining whether to report sidelink measurement results to a base station, determining whether to report Uu link measurement results to a base station, reporting sidelink measurement results to a base station, reporting Uu link measurement results to a base station, performing a handover procedure to a target base station by determining whether to receive a handover indication to the target base station from the base station, performing a sidelink relay change procedure by determining whether to receive a sidelink relay change indication within a serving base station from the base station, performing a direct connection procedure to the serving base station by determining whether to instruct a direct connection from the sidelink relay to the serving base station from the base station, performing a procedure for changing the target base station and the sidelink relay by determining whether to instruct a sidelink relay from the serving base station to the target base station, and performing a procedure for changing the target base station and the sidelink relay. The present disclosure provides the following process: if it is determined that the terminal needs to perform a path change procedure in the serving base station or a handover and path change procedure to the target base station, the sidelink connection with the serving sidelink relay is released, the sidelink connection with the target sidelink relay is established, the direct connection with the serving base station is changed, the direct connection with the serving base station is released, the direct connection with the target base station is established through the sidelink connection with the target sidelink relay, or the direct connection with the target base station is established.

Thus, according to an embodiment of the present disclosure, a method for handling connection mode mobility of a terminal capable of data/signaling transmission and reception with a base station through a side link relay in a wireless communication system, the method comprising: determining whether a side link monitoring and channel measurement are required when the terminal is connected to the serving base station directly or through a side link relay; performing side link monitoring and channel measurement; determining whether sidelink monitoring and channel measurement results need to be reported; reporting the side link monitoring and channel measurements to a serving base station; determining whether Uu link monitoring and channel measurement are needed; performing Uu link monitoring and channel measurement; determining whether Uu link monitoring and channel measurement results need to be reported; reporting the link monitoring and channel measurement results to a serving base station Uu; acquiring from a serving base station at least one of: a handover indication to a Uu cell of the same base station, a path change indication to a Uu cell of a serving base station, a path change indication to a new sidelink relay of the serving base station, a handover indication to a Uu cell of a target base station, or a path change indication to a sidelink relay of the target base station; performing handover or path change according to a handover instruction or path change instruction acquired from a serving base station; determining whether a sidelink connection with a service sidelink relay needs to be maintained or released, and executing a related process according to a determination result; determining whether the RRC connection with the serving base station needs to be maintained or released, and performing a related procedure according to the determination result; determining whether a sidelink connection needs to be established with the target sidelink relay, and executing a related process according to a determination result; determining whether an RRC connection with the target base station is required, and executing a related process according to the determination result; when an RRC connection is established with a target base station, it is determined whether an RRC connection procedure for direct connection or an RRC connection procedure through a sidelink relay is required, and a related procedure is performed according to the determination result.

According to embodiments of the present disclosure, by enabling a terminal to transmit and receive data/signaling with a base station through a sidelink relay, it is possible to extend service coverage, increase reliability of data transmission and reception, and minimize battery consumption of the terminal.

In the following description, for convenience, terms related to signals, terms related to channels, terms related to control information, terms related to network entities, terms related to device components, etc. are illustratively used. Accordingly, the present disclosure is not limited to the terms used below, and other terms indicating subjects having equivalent technical meanings may be used.

Hereinafter, the base station is a subject to perform resource allocation of the terminal, and may be at least one of a gNode B (gNB), an eNode B (eNB), a Node B, a Base Station (BS), a radio access unit, a base station controller, or a Node on a network. A terminal may include a User Equipment (UE), a Mobile Station (MS), a mobile phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. However, this is merely exemplary, and the base station and the terminal are not limited to these examples. In this disclosure, for ease of description, enbs may be used interchangeably with gNB. That is, a base station described as an eNB may indicate a gNB. In this disclosure, the term terminal may indicate various wireless communication devices as well as mobile phones, NB-IoT devices, and sensors.

In the following description, physical channels and signals may be used interchangeably with data or control signals. For example, although a Physical Downlink Shared Channel (PDSCH) refers to a term of a physical channel through which data is transmitted, the PDSCH may also be used to refer to data. That is, in the present disclosure, the expression "transmitting a physical channel" may be interpreted as being equivalent to the expression "transmitting data or signals through a physical channel".

Hereinafter, in the present disclosure, advanced signaling refers to a method of transmitting a signal from a base station to a UE using a downlink data channel of a physical layer or transmitting a signal from a UE to a base station using an uplink data channel of a physical layer. Advanced signaling may be understood as Radio Resource Control (RRC) signaling or Medium Access Control (MAC) Control Elements (CEs).

Further, in the present disclosure, in order to determine whether a specific condition is satisfied or fulfilled, an expression greater or less is used, but this is merely a description for representing examples and does not exclude descriptions of a specific number or more, or a specific number or less. Conditions described as "a specific number or more" may be replaced by "more than a specific number", conditions described as "a specific number or less" may be replaced by "less than a specific number", and conditions described as "a specific number or more, and less than a specific number" may be replaced by "more than a specific number, and a specific number or less".

Furthermore, although the present disclosure uses terminology for some communication standards (e.g., third generation partnership project (3 GPP)) to describe embodiments, this is merely an example for description. Embodiments of the present disclosure may be readily modified and applied in other communication systems.

Fig. 1a shows a base station 110, UEs 130 and 140, and a sidelink relay 120 capable of relaying data transmission and reception between the base station and the UEs, as some nodes using radio channels in a wireless communication system. Here, the sidelink relay corresponds to a relay of the UE to the network (U2N). Although fig. 1a shows only one base station, other base stations that are the same or similar to base station 110 may also be included.

Base station 110 is a network infrastructure that provides radio access to UEs 130 and 140 and relay 120. Based on the distance over which the signal can be transmitted, the base station 110 has a coverage area defined as a specific geographical area. In addition to the base station, the base station 110 may be referred to as an "Access Point (AP)", "eNodeB (eNB)", "fifth generation node (5G node)", "next generation node B (gNB)", "wireless point", "transmission/reception point (TRP)", or any other term having an equivalent technical meaning.

Relay 120 is a device used by a user or network infrastructure and may communicate with base station 110 over a radio channel. The link from the base station 110 to the relay 120 may be referred to as a Downlink (DL), and the link from the relay 120 to the base station 110 may be referred to as an Uplink (UL). The base station 110 and the relay 120 may be connected through a Uu interface. The Uplink (UL) refers to a wireless link where the relay 120 transmits data or control signals to the base station 110, and the Downlink (DL) refers to a wireless link where the base station 110 transmits data or control signals to the relay 120.

Relay 120 may communicate with UEs 130 and 140 over a wireless channel. The link between relay 120 and UE 130 or 140 is referred to as a sidelink, which may be referred to as a PC5 interface.

Each of the UEs 130 and 140 is a device used by a user, and may perform communication with the base station 110 through a radio channel or with the relay 120 through a radio channel. In the present disclosure, only a case where each of the UEs 130 and 140 communicates with the repeater 120 through a radio channel is shown. At least one of UEs 130 and 140 may operate without user involvement. That is, as an apparatus performing Machine Type Communication (MTC), at least one of UEs 130 and 140 may not be carried by a user. Each of UEs 130 and 140 may be referred to as a "terminal," "User Equipment (UE)", "mobile station," "subscriber station," "remote terminal," "wireless terminal," "user equipment," or any other terminology having an equivalent technical meaning.

Fig. 1b shows UEs 150 and 170 and a sidelink relay 160 capable of relaying data transmission and reception between UEs as some nodes using radio channels in a wireless communication system. Here, the sidelink relay 160 corresponds to a UE-to-UE (U2U) relay.

Relay 160 may communicate with UEs 150 and 170 over a wireless channel. The link between the relay 160 and the UE 150 or 170 is referred to as a sidelink, which may be referred to as a PC5 interface.

Each of the UEs 150 and 170 is a device used by a user, and may perform direct communication through a radio channel or communication with the repeater 160 through a radio channel. The links between UEs 150 and 170, between UE 150 and relay 160, and between UE 170 and relay 160 are referred to as sidelinks, which may also be referred to as PC5 interfaces.

At least one of UEs 150 and 170 may operate without user involvement. That is, as an apparatus performing Machine Type Communication (MTC), a user may not carry at least one of the UEs 150 and 170 and may not be carried by the user. Each of UEs 150 and 170 may be referred to as a "terminal," "User Equipment (UE)", "mobile station," "subscriber station," "remote terminal," "wireless terminal," "user equipment," or any other term having an equivalent technical meaning.

In the following description, uplink or downlink and Uu interfaces may be used interchangeably, and side-link and PC-5 interfaces may be used interchangeably.

The base station 110, relays 120 and 160, and UEs 130, 140, 150 and 170 shown in fig. 1a and 1b may transmit and receive radio signals in millimeter wave bands (e.g., 28GHz, 30GHz, 38GHz, and 60 GHz). In this case, the base station 110, the relays 120 and 160, and the UEs 130, 140, 150 and 170 may perform beamforming to improve channel gain. Here, beamforming may include transmit beamforming and receive beamforming. That is, the base station 110, the relays 120 and 160, and the UEs 130, 140, 150 and 170 may impart directivity to a transmission signal or a reception signal. To this end, the base station 110, the relays 120 and 160, and the UEs 130, 140, 150 and 170 may select the service beams 112, 113, 121, 131, 141, 151, 161 and 171 through a beam search or beam management procedure. After the service beams 112, 113, 121, 131, 141, 151, 161, and 171 are selected, subsequent communications may be performed through resources having a quasi-co-located (QCL) relationship with the resources that have transmitted the service beams 112, 113, 121, 131, 141, 151, 161, and 171.

The first antenna port and the second antenna port may be evaluated to be in QCL relationship if the large scale characteristics of the channel on which the symbol has been transmitted on the first antenna port can be inferred from the channel on which the symbol has been transmitted on the second antenna port. For example, the large scale characteristic may include at least one of delay spread, doppler shift, average gain, average delay, or spatial receiver parameters.

UEs 130, 140, 150, and 170 shown in fig. 1a and 1b may support in-vehicle communication. In the case of in-vehicle communication, standardization of the internet of vehicles (V2X) technology is completed in 3GPP releases 14 and 15, and standardization of the V2X technology based on 5G NR is completed in 3GPP release 16, based on a device-to-device (D2D) communication structure in the LTE system. NR V2X may support unicast, multicast (or multicast) and broadcast communications between UEs. Further, unlike LTE V2X, which is intended to transmit and receive basic security information required for vehicle road running, NR V2X is intended to provide higher-level services such as queue planning, advanced driving, extension sensors, and remote driving. V2X services can be classified into basic security services and advanced services. The basic security service may include a vehicle notification (cooperative sensing message (CAM) or Basic Security Message (BSM)) service and detailed services such as a left turn notification service, a front collision warning service, an emergency vehicle approach notification service, a front obstacle warning service, and an intersection signal information service, and may transmit/receive V2X information using a broadcast, unicast, or multicast transmission scheme. Advanced services not only have stronger quality of service (QoS) requirements than basic security services, but also require schemes for transmitting/receiving V2X information by using unicast and multicast transmission schemes other than broadcasting so that V2X information can be transmitted/received within a specific vehicle group or between two vehicles. Advanced services may include detailed services such as a platoon planning service, an autopilot service, a remote driving service, and an extended sensor based V2X service. Further, in an area without network infrastructure, NR V2X can provide public safety service by supporting a direct communication service between UEs.

Hereinafter, the Side Link (SL) refers to a transmission/reception path for a signal between UEs or a transmission/reception path for a signal between a UE and a relay, and may be used interchangeably with the PC5 interface. Hereinafter, as a body for performing UE resource allocation, the base station may be a base station supporting both V2X communication and general cellular communication, or a base station supporting only V2X communication. That is, a base station may refer to an NR base station (e.g., a gNB), an LTE base station (e.g., an eNB), or a Road Site Unit (RSU). Typically comprising a User Equipment (UE) or mobile station, a terminal may comprise a vehicle supporting vehicle-to-vehicle (V2V) communication, a vehicle or pedestrian handset (e.g., a smart phone) supporting vehicle-to-pedestrian (V2P) communication, a vehicle supporting vehicle-to-network (V2N) communication, a vehicle supporting vehicle-to-infrastructure (V2I) communication, an RSU with a UE function, an RSU with a base station function, or an RSU with a portion of a base station function and a portion of a UE function.

Meanwhile, in the present disclosure, a UE may refer to a vehicle supporting vehicle-to-vehicle (V2V) communication, a vehicle or pedestrian handset (e.g., a smart phone) supporting vehicle-to-pedestrian (V2P) communication, a vehicle supporting vehicle-to-network (V2N) communication, or a vehicle supporting vehicle-to-infrastructure (V2I) communication. A UE may refer to a user equipment that supports communication between public safety network devices.

Further, in the present disclosure, a UE may refer to a Road Site Unit (RSU) equipped with a UE function, an RSU equipped with a base station function, or an RSU equipped with a part of a base station function and a part of a UE function.

In this disclosure, a relay may refer to a vehicle supporting V2X communication or a user equipment supporting communication between public safety network devices. Further, in the present disclosure, a relay may refer to an apparatus equipped with a UE function, an apparatus equipped with a base station function, or an apparatus equipped with a part of a UE function and a part of a base station function.

The structure shown in fig. 2 may be understood as the structure of the base station 110. Terms such as "… … unit", "… … unit" and the like are used below to refer to a unit that processes at least one function or operation, and this may be implemented by hardware, software, or a combination of hardware and software.

Referring to fig. 2, the base station 110 may include a wireless communication unit 210, a backhaul communication unit 220, a memory 230, and a controller 240. However, the elements of the base station 110 are not limited to the above examples. For example, a base station may include more or fewer elements than those described above. Further, the wireless communication unit 210, the backhaul communication unit 220, the memory 230, and the controller 240 may be implemented in the form of a single chip. Further, the controller 240 may include one or more processors.

The wireless communication unit 210 may perform functions for transmitting and receiving signals through a radio channel. For example, the wireless communication unit 210 may perform a conversion function between a baseband signal and a bit stream according to a physical layer standard of a system. For example, in transmitting data, the wireless communication unit 210 may encode and modulate a transmission bit stream to generate complex symbols. Further, upon receiving the data, the wireless communication unit 210 may restore a received bit stream by demodulation and decoding of the baseband signal.

Further, the wireless communication unit 210 up-converts the baseband signal into a Radio Frequency (RF) band signal, transmits the RF band signal through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. To this end, the wireless communication unit 210 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and the like. Further, the wireless communication unit 210 may include a plurality of transmission and reception paths. Also, the wireless communication unit 210 may include at least one antenna array composed of a plurality of antenna elements.

In terms of hardware, the wireless communication unit 210 may be composed of a digital unit and an analog unit, and the analog unit may be composed of a plurality of sub-units according to operating power, operating frequency, and the like. The digital unit may be implemented with at least one processor, such as a Digital Signal Processor (DSP).

As described above, the wireless communication unit 210 transmits and receives signals. Accordingly, all or a portion of the wireless communication unit 210 may be referred to as a "transmitter," receiver, "or" transceiver. Further, in the following description, transmission and reception performed through a wireless channel are used in a sense including the processing performed by the wireless communication unit 210 as described above.

Backhaul communication unit 220 may provide an interface for performing communications with other nodes in the network. That is, the backhaul communication unit 220 may convert a bit stream transmitted from the base station 110 to another node (e.g., another access node, another base station, an upper node, a core network, etc.) into a physical signal, and convert a physical signal received from any other node into a bit stream.

Memory 230 may store default programs, application programs, and data such as configuration information for operation of base station 110. The memory 230 may be comprised of volatile memory, nonvolatile memory, or a combination thereof. Further, the memory 230 may provide stored data in response to a request of the controller 240.

The controller 240 may control the overall operation of the base station. For example, the controller 240 may transmit and receive signals through the wireless communication unit 210 or the backhaul communication unit 220. In addition, the controller 240 writes and reads data in the memory 230. In addition, the controller 240 may perform functions of a protocol stack required in a communication standard. According to another implementation example, a protocol stack may be included in the wireless communication unit 210. To this end, the controller 240 may include at least one processor. According to various embodiments, the controller 240 may control the base station to perform operations according to various embodiments, which will be described later.

The configuration shown in fig. 3 may be understood as the configuration of UE 120. Terms such as "… … unit", "… … unit" and the like are used below to refer to a unit that processes at least one function or operation, and this may be implemented as hardware or software, or a combination of hardware and software.

Referring to fig. 3, ue 120 may include a communication unit 310, a memory 320, and a controller 330. However, elements of UE 120 are not limited to the above examples. For example, UE 120 may include more or fewer elements than those described above. In addition, the communication unit 310, the memory 320, and the controller 330 may be implemented in the form of a single chip. Further, the controller 330 may include one or more processors.

The communication unit 310 performs a function for transmitting and receiving signals through a radio channel. For example, the communication unit 310 may perform a conversion function between a baseband signal and a bit stream according to a physical layer standard of a system. For example, when transmitting data, the communication unit 310 encodes and modulates a transmission bit stream, thereby generating complex symbols. Further, when receiving data, the communication unit 310 restores a received bit stream by demodulating and decoding a baseband signal. Further, the communication unit 310 up-converts the baseband signal into an RF band signal, transmits the RF band signal through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the communication unit 310 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

Further, the communication unit 310 may include a plurality of transmission and reception paths. Further, the communication unit 310 may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit 310 may be composed of digital circuits and analog circuits, such as a Radio Frequency Integrated Circuit (RFIC). Here, the digital circuit and the analog circuit may be implemented as one package. Further, the communication unit 310 may include a plurality of RF chains. Further, the communication unit 310 may perform beamforming.

As described above, the communication unit 310 can transmit and receive signals. Thus, all or part of the communication unit 310 may be referred to as a "transmitter," receiver, "or" transceiver. Further, in the following description, transmission and reception performed through a radio channel are used in a sense including the processing performed by the communication unit 310 as described above.

The memory 320 may store default programs, application programs, and data such as configuration information for operation of the UE. The memory 320 may be comprised of volatile memory, nonvolatile memory, or a combination thereof. In addition, the memory 320 provides stored data in response to a request of the controller 330.

The controller 330 controls the overall operation of the UE. For example, the controller 330 may transmit and receive signals through the communication unit 310. In addition, the controller 330 writes and reads data in the memory 320. In addition, the controller 330 may perform the functions of a protocol stack required in the communication standard. To this end, the controller 330 may include or be part of at least one processor or microprocessor. In addition, the communication unit 310 and a part of the controller 330 may be referred to as a Communication Processor (CP). According to various embodiments, the controller 330 may control the UE 120 to perform operations according to various embodiments that will be described later.

Fig. 4 shows an example of a detailed configuration of the wireless communication unit 210 of fig. 2 or the communication unit 310 of fig. 3. Specifically, fig. 4 illustrates elements for performing beamforming as part of the wireless communication unit 210 of fig. 2 or the communication unit 310 of fig. 3.

Referring to fig. 4, the wireless communication unit 210 or the communication unit 310 may include a coding and modulation unit 402, a digital beamforming unit 404, a plurality of transmission paths 406-1 to 406-N, and an analog beamforming unit 408.

The coding and modulation unit 402 may perform channel coding. For channel coding, at least one of a Low Density Parity Check (LDPC) code, a convolutional code, or a polar code may be used. The encoding and modulation unit 402 may perform constellation mapping to generate modulation symbols.

The digital beamforming unit 404 may perform beamforming on digital signals (e.g., modulation symbols). To this end, digital beamforming unit 404 multiplies the modulation symbols by beamforming weights. Here, beamforming weights are used to change the amplitude and phase of the signal, and may be referred to as a "precoding matrix", "precoder", and the like. Digital beamforming unit 404 may output digitally beamformed modulation symbols to a plurality of transmission paths 406-1 through 406-N. In this case, the modulation symbols may be multiplexed, or the same modulation symbols may be provided to a plurality of transmission paths 406-1 to 406-N, depending on a multiple-input multiple-output (MIMO) transmission technique.

The plurality of transmission paths 406-1 through 406-N may convert the digitally beamformed digital signals to analog signals. To this end, each of the plurality of transmission paths 406-1 to 406-N may include an Inverse Fast Fourier Transform (IFFT) operation unit, a Cyclic Prefix (CP) insertion unit, a DAC, and an up-conversion unit. The CP insertion unit is used for an Orthogonal Frequency Division Multiplexing (OFDM) scheme and can be excluded in case any other physical layer scheme, for example, a filter bank multi-carrier (FBMC), is applied. That is, the plurality of transmission paths 406-1 through 406-N may provide independent signal processing for the plurality of streams generated by digital beamforming. However, depending on the implementation type, some elements of the multiple transmission paths 406-1 to 406-N may be commonly used.

The analog beamforming unit 408 may perform beamforming on the analog signal. To this end, the digital beamforming unit 404 may multiply the analog signal by beamforming weights. Here, the beamforming weights are used to change the amplitude and phase of the signal. In particular, the analog beamforming unit 408 may be configured differently depending on the connection structure between the plurality of transmission paths 406-1 to 406-N and the antennas. For example, each of the plurality of transmission paths 406-1 through 406-N may be connected to an antenna array. In another example, multiple transmission paths 406-1 through 406-N may be connected to one antenna array. In another example, multiple transmission paths 406-1 through 406-N may be adaptively connected to one antenna array or to two or more antenna arrays.

Referring to fig. 5, in the radio resource domain, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain is an OFDM symbol or a DFT-S-OFDM symbol, and N _symb The OFDM symbols or DFT-S-OFDM symbols 530 may be contained in one slot 505. Unlike a slot, in the NR system, the length of a subframe may be defined as 1.0ms, and the length of a radio frame 500 may be defined as 10ms. The smallest transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth may include a total of N _BW Subcarriers 525. Can be variably applied according to the system such asN _symb And N _BW Is set to a specific value of (a).

The basic unit of the time-frequency resource domain is a Resource Element (RE) 510, which may be represented by an OFDM symbol index or DFT-S-OFDM symbol index and a subcarrier index. A Resource Block (RB) 515 may be defined as N in the frequency domain _RB Successive subcarriers 520. Typically, the smallest transmission unit of data is an RB unit, and in an NR system, N _symb Is 14 and N _RB Is 12.

The time-frequency resource structure as shown in fig. 5 is applied to the Uu interface. Furthermore, the time-frequency resource structure as shown in fig. 5 may be similarly applied to the sidelink.

According to embodiments of the present disclosure, an operation procedure of a UE, a sidelink relay, and a base station for handling connection mode (RRC connection state) mobility of the UE in a case where the UE (also referred to as a remote UE) performs data transmission and reception by directly connecting with the base station and in a case where the UE performs data transmission and reception by connecting with the base station through a sidelink relay (also referred to as a relay or relay UE) will be described. The sidelink relay may be authorized for at least one of a particular service, a particular UE, a particular sidelink flow, a particular sidelink bearer, a particular unicast link, a particular source identifier, and a particular destination identifier, or a combination thereof. The sidelink relay may establish a direct connection with the authenticated UE at installation. The sidelink relay may establish a sidelink direct connection with the UE when a relay discovery message is received from the authenticated UE. Upon receiving a relay discovery message from an authenticated UE as a response to the relay discovery message sent by the sidelink relay itself, the sidelink relay may establish a sidelink direct connection with the UE. Upon receiving a PC5 direct link establishment request from an authenticated UE, the sidelink relay may establish a sidelink direct connection with the UE. The method for the PC5 direct link setup request for the side link relay and the UE to relay connection may include at least one of the following methods or a combination thereof: a method of inserting a "connection instruction by relay" in the general PC5 direct link establishment request message, a method of defining "PC 5 direct link establishment message for relay use" respectively, or a method of configuring relay using the general PC5 direct link establishment request message transmitted in a side link radio bearer (may be expressed as SLRB).

Referring to fig. 6, a ue 600 and a sidelink relay 610 may acquire configuration information necessary to perform sidelink relay discovery, sidelink relay selection, and sidelink data/signaling transmission/reception from a base station 620 (steps 601 and 602). Steps 601 and 602 may correspond to a case where UE 600 and sidelink relay 610 are located in a coverage area of a base station. If it is determined that the UE 600 or the sidelink relay 610 is out of coverage, configuration information necessary to perform sidelink relay discovery, sidelink relay selection, and sidelink data/signaling transmission/reception may be acquired from the pre-configuration. In step 603, by referring to the configuration information of step 601 and step 602, the UE 600 or the sidelink relay 610 may determine whether a condition for triggering the sidelink relay discovery process is satisfied. In step 604, the UE 600 or the sidelink relay 610 may perform a sidelink relay discovery procedure by referring to the configuration information of step 601 and step 602. In step 605, by referring to the configuration information of steps 601 and 602, the UE 600 or the sidelink relay 610 may perform a measurement procedure for selecting the sidelink relay, and the sidelink relay selection may be based on the configuration condition.

An embodiment of the criteria for determining whether the UE establishes a direct connection with the base station is as follows. The UE may determine to perform a procedure of directly connecting to the base station if at least one of the following or a combination thereof is determined: the UE finds a connectable cell through a cell selection or cell reselection procedure, or there is a sidelink relay connectable to the base station but does not satisfy a connection establishment condition with the sidelink relay (for example, a signal measurement value such as a sidelink reference signal received power (SL RSRP) transmitted by the sidelink relay is lower than a threshold value). An embodiment of the criteria for determining whether a UE establishes a connection to a base station through a connection with a sidelink relay is as follows. The UE may determine to perform a procedure to connect to the base station via the sidelink relay if at least one of or a combination of the following is determined: there is no connectable cell through the cell selection or cell reselection procedure or the base station direct connection condition is not satisfied but the connection establishment condition with the sidelink relay is satisfied.

In step 606, the ue 600 and the sidelink relay 610 may establish a sidelink direct connection to perform data/signaling transmission/reception with the base station 620 through the sidelink relay. The sidelink direct connection establishment procedure follows the PC5-S signaling message transmission and reception procedure of the V2X layer of the UE 600 and the sidelink relay 610. In addition, UE 600 and sidelink relay 610 may perform a PC5RRC procedure. The PC5RRC procedure may include a UE capability query sidelink/UE capability information sidelink message procedure for exchanging sidelink capability information and a rrcrecnonfigurationsidelink message procedure for setting a PC5RRC configuration. The PC5RRC configuration setup procedure may also be performed to configure the PC5 SLRB to be applied when the UE 600 and the sidelink relay 610 transmit and receive data/signaling between the UE 600 and the base station 620 through the sidelink interface. In step 607, the ue 600 may perform an RRC connection establishment procedure to the base station 620 through the sidelink relay 610. Through the procedure of step 607, the base station 620 may configure a Data Radio Bearer (DRB)/Signaling Radio Bearer (SRB) for data/signaling purposes of the UE 600. Through the procedure of step 607, the base station 620 may configure a PC5 SLRB mapped with the DRB/SRB of the UE 600 in the UE 600 and the sidelink relay 610. The UE 600 and the sidelink relay 610 may use the configured PC5 SLRB to transmit and receive data/signaling transmitted by the UE 600 to the base station 620, and transmit and receive data/signaling transmitted by the base station 620 to the UE 600. The sidelink relay 610 may relay data/signaling between the UE 600 and the base station 620 by: an operation of mapping data/signaling corresponding to the PC5 SLRB of the UE 600 to Uu DRB/SRB, and an operation of mapping data/signaling corresponding to the Uu DRB/SRB of the UE 600 to the PC5 SLRB. Meanwhile, step 607 may begin when the UE 600 transmits an rrcsetup request message for initiating an RRC connection setup procedure with the base station 620.

Mobility scenarios that can be considered in the connected mode of the UE are shown in table 1.

TABLE 1

In the case where the UE supports connection establishment with the base station through the sidelink relay in addition to direct connection establishment with the base station, the UE may perform a change from connection with one sidelink relay to connection with another sidelink relay for the sidelink relay, as shown in table 1. This will be described as a sidelink relay change operation. An operation in which the UE changes from being connected to a direct connection with the serving base station through the sidelink relay a or an operation in which the UE changes from being connected to the serving base station directly to being connected through the sidelink relay a will also be described as a sidelink relay change operation. The sidelink relay change operation may be a change within the same serving base station or a change from the serving base station to the target base station. In the case of a direct connection between a UE and a base station in an existing communication system, the UE performing a change from a connection with a serving base station to a connection with a target base station operation may mean a handover. In the embodiment of the present disclosure, an operation of changing from connection with a serving base station through a sidelink relay a to direct connection with a target base station, an operation of changing from connection with a serving base station to connection with a target base station through a sidelink relay B, and an operation of changing from connection with a serving base station through a sidelink relay a to connection with a target base station through a sidelink relay B will be described as sidelink relay changing operation.

The serving base station of the UE may control the connection mode mobility of the UE. For example, the serving base station may send configuration information indicating Uu link monitoring and measurement reports to the UE. The base station may send configuration information indicating the sidelink monitoring and measurement reports to the UE. In case the UE is directly connected to the base station, the monitoring and measurement report instruction configuration information may be transmitted through RRC signaling of the Uu interface between the base station and the UE. In case the UE is connected to the base station through the sidelink relay, the monitoring and measurement report instruction configuration information may be transmitted through an RRC signaling relay between the base station and the UE via the sidelink relay. The serving base station may obtain reporting results for monitoring/measuring Uu link or sidelink of the UE through direct connection from the UE or relay transmission through sidelink relay. The UE may be instructed to perform at least one of a conventional handover, a conditional handover, and a DAPS handover even when directly connected to the base station or connected to the base station through a sidelink relay. When the UE makes an RRC connection with the serving base station through the sidelink relay, the sidelink relay may perform an operation of relaying transmission RRC signaling including a connection mode mobility control configuration of the UE or a handover instruction between the UE and the serving base station. RRC signaling or handover indication configured for UE connected mode mobility control may be transmitted and received between the UE and the sidelink relay over the PC5 SLRB configured between the UE and the sidelink relay. When the UE is directly connected to the serving base station, the target sidelink relay in the serving base station may obtain at least one of sidelink relay Uu relay RLC channel configuration information required for the UE to relay signaling/data for path change, and PC5 SRB/DRB configuration information with the UE, or a combination thereof, through the serving base station. A UE changing a path to a target sidelink relay by using at least one of the sidelink relay Uu relay RLC channel configuration information and the PC5 SRB/DRB configuration information of the UE or a combination thereof may maintain a connection with a base station through the target sidelink relay and relay transmission data/signaling transmission/reception.

In case of supporting the sidelink relay, the serving base station and the neighboring base station may exchange sidelink relay information managed by the base station through an inter-node message based on Uu link measurement results and sidelink link measurement results reported by the UE for the UE connection mode mobility, and exchange information about sidelink relay of the target base station and the target base station through an inter-node message, which the UE may perform handover and path change. The serving base station and the neighbor base station may exchange at least one of Uu capability of the UE, sidelink capability of the UE, uu SRB/DRB configuration information of the UE, PC5 SRB/DRB configuration information of the UE, and PC5 SRB/DRB configuration information between the UE and the target base station, or a combination thereof, which are required for the UE to: the handover and path change are performed on the target base station or the side link relay of the target base station, and the connection is established with the target base station or the side link relay of the target base station.

Referring to fig. 7, in case that a UE is authenticated to transmit and receive data/signaling with a base station through a sidelink relay, the UE may perform at least one operation of the mobility scheme in [ table 1 ]. When receiving the rrcrecon configuration message indicating the handover or the sidelink relay change from the serving base station, the ue may acquire information indicating the following from the handover or sidelink relay change indication configuration information in the rrcrecon configuration message in step 700: whether a handover or a sidelink relay change is indicated within the serving base station or whether a handover or sidelink relay change is indicated within a neighboring base station.

If it is determined in step 701 that the configuration information indicates that a handover or a sidelink relay change is performed in the serving base station, the ue may determine in step 702 whether the configuration information indicates a direct connection with the serving base station or indicates a connection with the base station through a sidelink relay in the serving base station. In case of a direct connection with a serving base station, step 703 may be performed. In step 703, the ue may determine whether a PC5 direct link release procedure with the sidelink relay of the currently connected serving base station is required. The UE may determine to release a PC5 SLRB configured for data/signaling bearer relay transmission between the UE and the base station using the serving sidelink relay, and then perform a procedure for releasing the PC5 SLRB with the sidelink relay. In addition to the purpose of relay transmission using sidelink relay, in the case where PC5 direct link establishment and PC5 RRC establishment must be maintained for separate sidelink direct communication purposes, the UE may determine a configuration to maintain the separate sidelink direct communication purposes. In step 704, the ue may obtain configuration information of at least one of a Uu L1 (PHY) entity, a Uu MAC entity, and a Uu RLC entity, or a combination thereof, from the base station, the configuration information being necessary for direct connection establishment with the serving base station and being configured by the base station. If it is determined in step 702 that the configuration information indicates connection with the base station through a sidelink relay in the serving base station, the UE may perform step 705. In step 705, the ue may determine whether a PC5 direct link release procedure with a sidelink relay of a currently connected serving base station is required. The UE may determine to release a PC5 SLRB configured for data/signaling bearer relay transmission between the UE and the base station using the serving sidelink relay, and then perform a procedure for releasing the PC5 SLRB with the sidelink relay. In addition to the purpose of relay transmission using sidelink relay, in the case where PC5 direct link establishment and PC5 RRC establishment must be maintained for separate sidelink direct communication purposes, the UE may determine a configuration to maintain the separate sidelink direct communication purposes. The UE may determine that a PC5 direct link establishment procedure with the target sidelink relay is required. The UE may configure the PC5 SLRB for relay transmission of data/signaling bearers between the UE and the base station using the target sidelink relay. The PC5 SLRB for relay transmission may be configured by acquiring configuration information of at least one of a PC 5L 1 (PHY) entity, a PC5 MAC entity, and a PC5 RLC entity, or a combination thereof, from the base station.

If it is determined in step 701 that the configuration information indicates that a handover or a sidelink relay change is performed in the target base station, the ue may determine in step 707 whether the configuration information indicates a direct connection with the target base station or indicates a connection with the base station through a sidelink relay in the target base station. In case of a direct connection with the target base station, step 708 may be performed. In step 708, the ue may determine whether to establish a connection through a sidelink relay of the serving base station. If it is determined in step 708 that the UE is connected to a sidelink relay, the UE may determine in step 709 whether a PC5 direct link release procedure with the serving sidelink relay is required. The UE may determine to release a PC5 SLRB configured for data/signaling bearer relay transmission between the UE and the base station using the serving sidelink relay, and then perform a procedure for releasing the PC5 SLRB with the sidelink relay. In addition to the purpose of relay transmission using sidelink relay, in the case where PC5 direct link establishment and PC5 RRC establishment must be maintained for separate sidelink direct communication purposes, the UE may determine a configuration to maintain the separate sidelink direct communication purposes. In step 710, the ue may perform an RRC connection establishment procedure with the target base station. In step 710, the ue may perform a synchronization acquisition and random access procedure (at least one of contention-free, contention-based, 2-step RACH, or 4-step RACH) with the target base station and perform a bearer establishment procedure required for RRC connection establishment and data/signaling transmission and reception through a direct connection with the target base station. The operation performed by the UE in step 710 may correspond to a procedure in which the UE establishes a connection with a target base station and releases a connection with a serving base station at the time of general handover of the Uu interface. That is, the UE may release the Uu SDAP entity and the Uu PDCP entity obtained from the RRC connection with the serving base station and establish a radio bearer with the target base station. If it is determined in step 708 that the UE receives a handover indication from a direct connection with the serving base station to the target base station, the UE may perform the operation of step 710.

If it is determined in step 707 that the configuration information indicates connection with the base station through the sidelink relay in the target base station, the UE may perform step 711. In step 711, the ue may determine whether to establish a connection through a sidelink relay of the serving base station. If it is determined in step 711 that the UE is connected to the sidelink relay, the UE may determine in step 712 whether a PC5 direct link release procedure with the serving sidelink relay is required. The UE may determine to release a PC5 SLRB configured for data/signaling bearer relay transmission between the UE and the base station using the serving sidelink relay, and then perform a procedure for releasing the PC5 SLRB with the sidelink relay. In addition to the purpose of relay transmission using sidelink relay, in the case where PC5 direct link establishment and PC5 RRC establishment must be maintained for separate sidelink direct communication purposes, the UE may determine a configuration to maintain the separate sidelink direct communication purposes.

In step 713, the ue may perform a target sidelink relay with the target base station PC5 direct link setup procedure. In step 714, the ue may perform an RRC connection establishment procedure with the target base station by using PC5 direct link establishment with the target sidelink relay. The UE may configure RRC entity, uu SDAP entity, and Uu PDCP entity of data/signaling radio bearers between the UE and the target base station by performing an RRC establishment procedure with the target base station instead of performing a synchronization acquisition and random access procedure with the target base station. The UE may configure a PC 5L 1 (PHY) entity, a PC5MAC entity, and a PC5 RLC entity for transmitting relay data/signaling radio bearers between the UE and the target base station using target sidelink relay. In step 714, the UE may perform connection release with the serving base station, i.e., the UE may release the Uu SDAP entity and the Uu PDCP entity obtained from the RRC connection with the serving base station. If it is determined in step 711 that the UE is indicated to change the relay from the direct connection with the serving base station to the target sidelink relay of the target base station, the UE may perform the operations of steps 713 and 714.

Referring to fig. 8, in step 801, a base station 830 may transmit an rrcrecon configuration message to a sidelink relay 820, the message including a measurement configuration and a measurement report configuration for UE 800 to perform connected mode mobility management, wherein UE 800 transmits and receives data/signaling with base station 830 through a sidelink connection with sidelink relay 820. To obtain the information necessary for the measurement configuration and the measurement report configuration, the base station 830 may exchange at least one of the information in [ table 2] or a combination thereof with the sidelink relay connected to the neighboring base station and the serving base station. The neighboring base station may also exchange this information with the sidelink relay connected thereto.

TABLE 2

The rrcrecon configuration message of step 801 may be mapped to a sidelink relay Uu relay RLC channel intended for the UE 800. In step 802, the sidelink relay 820 may send an rrcrecon configuration message to the UE 800 over the PC5 RLC channel, wherein the UE 800 is mapped to a sidelink relay Uu relay RLC channel. In step 802, in order to be mapped to a signaling bearer (e.g., a bearer corresponding to RRC signaling) transmitted from the base station 830 (downlink) or transmitted to the base station 830 (uplink) between the UE 800 and the sidelink relay 820, the same sidelink signaling bearer as the sidelink RRC may be configured, or a separate sidelink radio bearer (signaling or data) may be configured. At this time, if the same mode as the RLC mode corresponding to Uu RRC signaling (i.e., RLC mode of Uu RRC) is TM, the RLC mode of the sidelink radio bearer may be configured as TM. Similarly, if the RLC mode of Uu RRC is AM, the RLC mode of the sidelink radio bearer may be configured as AM, and if the RLC mode of Uu RRC is UM, the RLC mode of the sidelink radio bearer may be configured as UM. This is a configuration for performing RLC mode processing of the same level as Uu RRC in the sidelink. In step 803, the ue 800 may acquire measurement configuration and measurement report configuration information included in the rrcrecon configuration message, and may perform an operation according to the measurement configuration and the measurement report configuration. The measurement configuration and measurement report configuration may include at least one of the following [ table 3] or a combination thereof.

TABLE 3

Based on the measurement configuration and the measurement report configuration of step 803, the UE 800 may perform at least one of Uu interface measurements and sidelink interface measurements, or a combination thereof. In the case of performing the sidelink interface measurement, if the UE 800 is configured to monitor the sidelink relay discovery message, perform the measurement and report it, the UE 800 may be configured to report the physical cell ID of the serving base station (or serving cell) of the sidelink relay acquired from the sidelink relay discovery message. In step 804, the ue 800 may transmit an RRC measurement report message to the base station 830. In step 805, the RRC measurement report message of the ue 800 may be relayed to the base station 830 through the sidelink relay 820. The ue 800 and the sidelink relay 820 may transmit and receive the RRC measurement report on the sidelink by using the PC5 SLRB configured as Uu SRB mapped to the RRC measurement report in step 804, and the sidelink relay 820 may transmit the RRC measurement report to the base station 830 in a sidelink relay Uu RLC channel mapped to an RLC channel of the PC5 SLRB in step 805. The RRC measurement report message of the UE 800 may include at least one of measurement results of the Uu interface and measurement results of the sidelink interface or a combination thereof. The measurement of the sidelink interface may include sidelink relay information and may report information including at least one of or a combination of: a sidelink relay identifier (at least one of a relay code, a 2 nd relay layer ID, and a relay identifier, or a combination thereof), a measurement result value of the sidelink relay (e.g., SL-RSRP), and a physical cell ID of a serving cell/base station of the sidelink relay. The base station 830 may manage the connection mode mobility of the UE 800 based on RRC measurement reports of the UE 800, information obtained by the base station 830 from neighboring base stations, information obtained by the base station 830 from a core network, and the like. For example, the base station may determine a need for a handover or a sidelink relay change for the UE 800. In the present disclosure, a connection change in which the UE 800 directly connects to the serving base station or the target base station is indicated as handover, and a connection change in which the UE 800 connects to a sidelink relay in the serving base station or the target base station is indicated as sidelink relay change.

In the case of indicating a handover or a sidelink relay change, the base station 830 may transmit an rrcrecon configuration message including at least one of or a combination of the following to the UE 800 in step 806: configuration information required for establishing a connection with a new base station, including at least one of Uu RRC, uu PDCP, uu SDAP, uu RLC, uu MAC, uu L1 (PHY), synchronization configuration, or random access configuration; or configuration information required for establishing a connection with the new sidelink relay, including at least one of a PC5 RLC, a PC5 MAC, or a PC 5L 1 (PHY) configuration. For example, in the case where the UE 800 needs to perform a sidelink relay change to a new base station, the information sent by the base station 830 in RRC reconfiguration may include at least one or a combination of the following: uu RRC entity configuration information, uu PDCP entity configuration information, and Uu SDAP entity configuration information with the target base station, and PC5 RLC entity configuration information, PC5 MAC entity configuration information, and PC 5L 1 (PHY) entity configuration information of the sidelink relay with the target base station. According to an embodiment, the sidelink relay 820 may transmit an rrcrecon configuration message including information of a handover indication or a sidelink relay change indication to the UE 800 through the sidelink RLC channel in step 807. Based on the handover indication or the sidelink relay change indication in the rrcrecnonconfiguration message received from the base station 830, the ue 800 may access and establish a connection with the new target base station or the new sidelink relay in step 809.

Based on the handover indication or the sidelink relay change indication in the rrcrecondonconfiguration message received from the base station 830, the ue 800 may perform at step 809 at least one or a combination of the following: release the direct connection of PC5 with the serving sidelink relay (release the PC 5L 1 (PHY) entity configuration, PC5MAC entity configuration, PC5 RLC entity configuration for data/signaling transmission between the UE and the base station via sidelink relay 820), or release the Uu connection with the serving base station 830. In case the UE 800 performs a sidelink relay change to another sidelink relay in the serving base station 830, the UE 800 may maintain Uu RRC entity, uu PDCP entity, and Uu SDAP entity configurations with the serving base station 830 and use them for data/signaling transmission and reception with the serving base station 830 even when connected to a new sidelink relay.

Next, with reference to fig. 9 and 10, an operation of releasing the sidelink connection with the sidelink relay in step 809 of fig. 8 in the following case will be described: the UE receives a sidelink relay change indication for another sidelink relay in the serving base station, a sidelink relay indication from a sidelink relay connection to a base station direct connection, a sidelink relay change indication from a sidelink relay connection to a target base station direct connection, or a sidelink relay change indication for a sidelink relay for another base station.

Fig. 9 illustrates the operation of releasing the sidelink PC5 connection between the UE 900 and the serving sidelink relay 910 in case the UE 900 no longer needs to transmit and receive data/signaling with the base station 920 via the serving sidelink relay 910. Based on the handover indication or the sidelink relay change indication in the rrcrecon configuration message received in step 807 of fig. 8, the UE 900 may determine that it is necessary to release the PC5 connection for sidelink relay configured for use with the sidelink relay 910. UE 900 may determine in step 901 that a PC5 connection with sidelink relay 910 needs to be released and may perform a PC5 connection release procedure with sidelink relay 910 by transmitting a PC5 connection release procedure request message to sidelink relay 910 in step 902. In step 902, the PC5 connection release procedure performed by the UE 900 and the sidelink relay 910 may include one of the following procedures in [ table 4] or [ table 5 ].

TABLE 4

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TABLE 5

Fig. 10 illustrates the operation of releasing the sidelink PC5 connection between the UE 1000 and the serving sidelink relay 1010 in the event that the UE 1000 no longer needs to transmit and receive data/signaling with the base station 1020 via the serving sidelink relay 1010. The sidelink relay 1010 may acquire configuration information from the base station 1020, the configuration information indicating release of a sidelink relay Uu RLC channel configured for data/signaling relay transmission between the UE 1000 and the base station 1020 or deletion of configuration information of the corresponding UE 1000 due to the UE 1000 performing handover or sidelink relay change. The sidelink relay 1010 may then determine that it is necessary to release the PC5 connection configured for sidelink relay with the UE 1000.

The sidelink relay 1010 may determine that the PC5 connection with the UE 1000 needs to be released in step 1001, and may perform a PC5 connection release procedure with the UE 1000 by transmitting a PC5 connection release procedure request message to the UE 1000 in step 1002. At step 1002, the PC5 connection release procedure performed by the UE 1000 and the sidelink relay 1010 may include one of the following procedures in table 6 or table 7.

TABLE 6

TABLE 7

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In the embodiment of fig. 8, an operation of the serving sidelink relay 820 and the serving base station 830 for the UE 800 to handle handover or sidelink relay change of the UE 800 will be described with reference to fig. 11a and 11 b.

Fig. 11a may be performed as follows: the serving base station 830 sends an rrcrecon configuration message to the UE 800 indicating a handover or a sidelink relay change and informs the serving sidelink relay 820 of the message, and the sidelink relay 820 releases the sidelink established for the UE 800 to relay transmissions that is no longer needed. As an embodiment, fig. 11a may be performed when the serving base station 830 transmits an rrcr configuration message to the UE 800 and receives an rrcr configuration complete message informing of handover or sidelink relay change completion from the UE 800 or a corresponding message from another base station. In the embodiment of fig. 11a, the serving base station 830 may transmit information about handover or sidelink relay change of the UE 800 to the sidelink relay 820 separately when transmitting an rrcrecon configuration message to the UE 800.

Referring to fig. 11a, in step 1101, the base station 1110 may transmit an rrcrecon configuration message including at least one of the following information or a combination thereof to the sidelink relay 1100: information informing the UE to perform handover or sidelink relay change, and information informing to release signaling/data relay configured between the UE and the base station. The rrcrecon configuration message may include at least one of the following information or a combination thereof: the UE's identification information to be released from the relay information by the sidelink relay 1100, and the sidelink relay Uu relay RLC channel information for the UE. The sidelink relay 1100 may send an rrcrecon configuration complete message to the base station 1110 in step 1102. In step 1103, the sidelink relay 1100 may perform a PC5 direct link release procedure with the UE, if necessary. For example, the sidelink relay 1100 may perform a PC5 direct link release procedure as shown in fig. 9 or 10. In step 1103, the sidelink relay 1100 may release bearer configuration information configured for relay between the UE and the base station 1110. For example, the information of the corresponding UE may be deleted in the side link relay Uu relay RLC channel configuration. In step 1103, the sidelink relay 1100 may report packet forwarding state information to the base station 1110 regarding packets being processed for relay transmission to the UE. The sidelink relay 1100 may send sidelink packets and Uu packets between the UE and the base station to the UE and the base station 1110, respectively, or may delete (discard) sidelink packets and Uu packets that are no longer needed for relay transmission.

Fig. 11b may be performed as follows: the sidelink relay 820 releases the sidelink that is no longer needed to establish for the UE 800 to relay transmissions, and the sidelink relay 820 informs the serving base station 830 that relay transmissions to the UE 800 are no longer performed. As an embodiment, the operation of fig. 11b may be performed after the sidelink relay 820 releases the PC5 direct link release procedure and the PC5 SLRB configuration for sidelink relay with the UE 800.

Referring to fig. 11b, in step 1151, the sidelink relay 1150 may determine that a PC5 direct link release and a PC5 SLRB release for sidelink relay with the UE are required. In step 1152, the sidelink relay 1500 may perform a PC5 direct link release procedure with the UE, if necessary. For example, the sidelink relay 1150 may perform a PC5 direct link release procedure as shown in fig. 9 or 10. In step 1152, the sidelink relay 1500 may release bearer configuration information configured for relaying between the UE and the base station 1160. For example, the information of the corresponding UE may be deleted in the side link relay Uu relay RLC channel configuration. In step 1152, side link relay 1150 may report packet forwarding state information to base station 1160 regarding packets being processed for relay transmission to the UE. The sidelink relay 1150 may send sidelink packets and Uu packets between the UE and the base station to the UE and the base station 1160, respectively, or may delete sidelink packets and Uu packets that are no longer needed for relay transmission. In step 1153, side link relay 1150 may send a sidlinkiueinformation message to base station 1160 indicating that relay transmissions to the UE are no longer performed. To inform a side link relay Uu relay RLC channel configured for signaling/data relay between the UE and the base station 1160 to be released, a SidelinkUEInformation message may be transmitted.

The embodiment of fig. 12a shows a procedure for performing the following operation in case the UE 1200 performs a sidelink relay change to the sidelink relay in the same serving base station 1230: the UE 1200 receives an operation of a sidelink relay change instruction of the target sidelink relay 1220 from the base station 1230, and then performs an operation of PC5 direct link connection establishment for connection with the base station 1230 and sidelink SLRB configuration for relay through the target sidelink relay 1220; and the target sidelink relay 1220 obtains from the base station 1230 an operation of sidelink relay configuration information necessary for signaling/data relay transmission between the UE 1200 and the base station 1230.

Referring to fig. 12a, in step 1201, the ue 1200 may acquire an rrcrecon configuration message including a sidelink relay change indication or handover indication information from the serving base station 1230 when transmitting and receiving signaling/data with the serving base station 1230 through a connection with a serving sidelink relay or a direct connection with the serving base station. The rrcrecnonfiguration message of step 1201 may be transmitted to the UE 1200 through a serving sidelink relay or directly from the serving base station 1230. In step 1202, the ue 1200 may determine that a connection to a new sidelink relay 1220 is required based on the indication obtained in step 1201.

In step 1203, the ue 1200 may perform a PC5 direct link connection establishment procedure with the target sidelink relay 1220. By triggering the UE 1200 receiving the rrcrecon configuration message in step 1201, the UE 1200 and the sidelink relay 1220 may perform a PC5 direct link setup procedure using PC5-S signaling of the V2X layer. The UE 1200 may set the PC5-S signaling protocol cause to "relay path switch" or "link establishment for indirect communication" and send a direct link establishment request PC5-S signaling to the target sidelink relay 1220. If the UE 1200 and the target sidelink relay 1220 have performed a PC5 direct link setup procedure for regular sidelink data transmission and reception instead of for relay transmission and maintain a PC5 direct link connection, the UE 1200 and the target sidelink relay 1220 may relay transmission using an existing PC5 direct link connection. In this case, the UE 1200 may set the PC5-S signaling protocol cause to "relay path switch" or "link establishment for indirect communication", and send a direct link modification request PC5-S signaling to the target sidelink relay 1220.

As another embodiment, in the case of relaying between the UE 1200 and the target sidelink relay 1220 using an already established PC5 direct link, the UE 1200 may send PC5 RRC signaling (e.g., rrcrecon configuration sidelink) indicating that a PC5 SLRB configuration for relaying is required to the target sidelink relay 1220. In addition, the ue 1200 and the target sidelink relay 1220 may also perform an SLRB configuration procedure using sidelink RRC signaling in step 1203.

As another embodiment, the ue 1200 and the target sidelink relay 1220 may not perform the sidelink SLRB configuration procedure in step 1203, but may perform the sidelink SLRB configuration procedure after acquiring sidelink SLRB configuration information for relay from the base station 1230.

Through the procedure of step 1203, the target sidelink relay 1220 may determine that data/signaling needs to be relayed between the UE 1200 and the base station 1230, and may acquire information of the UE 1200. In step 1205, the target sidelink relay 1220 may send a sidlinkiueinformation message to the base station 1230 reporting that relay transmissions to the UE 1200 are required.

The sidlinkueinformation message of step 1205 may include at least one of identification information of the UE 1200, information indicating that the SLRB configuration in the relay transmission of the UE 1200 is required, and side link transmission resource request information necessary for the relay transmission of the UE 1200, or a combination thereof. The identification information of the UE 1200 used in step 1205 may include a layer 2 ID of the UE 1200 or a unicast link ID of the UE 1200 and the target sidelink relay 1220, and the UE identification information may be used to distinguish the UE 1200 in a Relay Adaptation Protocol (RAP) sublayer of the base station 1230 and the target sidelink relay 1220. In the case of using the layer 2 ID as the identification information of the UE 1200, the layer 2 ID may be used for relay transmission with the previous service side link relay through the UE 1200. If it is determined that the 2 nd layer ID needs to be updated in case of connection with the target sidelink relay 1220, the UE 1200 may perform the 2 nd layer ID update procedure using the target sidelink relay 1220.

In step 1206, the base station 1230 may send relay configuration information required for data/signaling relay transmissions between the UE 1200 and the base station 1230 to the target sidelink relay 1220 and the RAP sublayer configuration information. When the base station 1230 transmits the relay configuration information or RAP sub-layer configuration information to the target sidelink relay 1220, the identification information of the UE 1200 reported in the SidelinkUEInformation message of step 1205 by the target sidelink relay 1220 may be included. In step 1208, the target sidelink relay 1220 may send an rrcr configuration complete message to the base station 1230 in response to the rrcr configuration message of step 1206. In addition, the base station 1230 may transmit side link SLRB configuration information for relay transmission to the target side link relay 1220 in step 1206, which may be the same as the side link SLRB configuration information used by the UE 1200 for relay transmission with the previous serving side link relay.

As another embodiment, in case the base station 1230 decides to change the sidelink SLRB configuration information for relay transmission between the target sidelink relay 1220 and the UE 1200, the base station 1230 may transmit the sidelink SLRB configuration information for sidelink relay transmission to the target sidelink relay 1220 and the UE 1200. In step 1207, the ue 1200 and the target sidelink relay 1220 may exchange PC5 RRC signaling to check or update sidelink SLRB configuration information for relay transmission. Checking the side link SLRB configuration information for relay transmission may correspond to: based on the side link SLRB configuration information that UE 1200 has configured with previously serving side link relay and in use for relay transmission, UE 1200 configures side link SLRB information for relay transmission with target side link relay 1220. Updating the sidelink SLRB configuration information for relay transmission between the UE 1200 and the target sidelink relay 1220 may correspond to the following operations: the side link SLRB information for relay transmission between the UE 1200 and the target side link relay 1220 is configured based on the side link SLRB configuration information newly obtained from the base station 1230. When the sidelink SLRB configuration for relay transmission between the UE 1200 and the target sidelink relay 1220 is completed, the UE 1200 may transmit an rrcr configuration complete message to the base station 1230 through the target sidelink relay 1220 in order to report that the sidelink relay change is completed in step 1209.

In case the UE 1200 performs a sidelink relay change procedure to the target sidelink relay 1220 while performing a direct connection with the base station 1230, the UE 1200 may release Uu L1 (PHY) entity configuration, uu MAC entity configuration, and Uu RLC entity configuration information of the Uu DRB/SRB, which are configured for a direct connection with the base station 1230, but are not necessary for relay transmission with the target sidelink relay 1220. The UE 1200 may use Uu PDCP entity configuration, uu SDAP entity configuration, and Uu RRC entity configuration information with the base station 1230 even when connected with the target sidelink relay 1220 unless the base station 1230 indicates a change. The UE 1200 may configure a PC 5L 1 (PHY) entity configuration, a PC5 MAC entity configuration, and PC5 RLC entity configuration information required for relay transmission with the target sidelink relay 1220.

In the case where the UE 1200 performs the sidelink relay change procedure to the target sidelink relay 1220 when performing a connection with the base station through the serving sidelink relay, the UE 1200 may perform operations of releasing the PC5 direct link and connection setup and the SLRB configuration, which are no longer required for relay transmission with the previous serving sidelink relay. PC5 direct link and connection setup and SLRB configuration, which should be used by UE 1200 and the previously serving sidelink relay for separate sidelink direct data transmission and reception instead of for relay transmission, can be continued to be used without being released. The operation procedure performed by the UE 1200 with the previous service side link relay for releasing PC5 direct link and connection establishment and SLRB configuration for relay transmission that are no longer needed is the same as the embodiment of fig. 9 or 10. The previous serving sidelink relay may release the RAP sublayer configuration information and the PC5SLRB configuration information configured for relay transmission of the UE 1200, and the operational procedures performed by the previous serving sidelink relay with the UE 1200 and the serving base station 1230 are shown in fig. 9 and 10 and fig. 11a and 11b, respectively.

The embodiment of fig. 12b shows a procedure in which the following is performed in case the UE 1250 performs a sidelink relay change to a sidelink relay in the same serving base station 1280: operation when UE 1250 receives a sidelink relay change instruction to target sidelink relay 1270 from base station 1280, and operation when target sidelink relay 1270 obtains configuration information necessary for PC5 direct link establishment for sidelink relay transmission with UE 1250 from base station 1280; the target sidelink relay 1270 performs sidelink SLRB configuration for PC5 direct link connection establishment connected with the UE 1250 and the base station 1280 and for relay, and the target sidelink relay 1270 obtains sidelink relay configuration information necessary for relay transmission of signaling/data between the UE 1250 and the base station 1280 from the base station 1280.

Referring to fig. 12b, in step 1251, the ue 1250 may acquire an rrcrecon configuration message including a sidelink relay change indication or handover indication information from the serving base station 1280 when transmitting and receiving signaling/data with the serving base station 1280 through a connection with a serving sidelink relay or a direct connection with the serving base station. The rrcrecon configuration message of step 1251 may be transmitted to UE 1250 by a serving sidelink relay or sent directly from serving base station 1280. In step 1252, the ue 1250 may determine that a connection to a new sidelink relay 1270 is required based on the indication obtained in step 1251. In step 1253, the target sidelink relay 1270 may acquire at least one of information of the UE 1250 from the base station 1280, relay configuration information required for relay transmission between the base station 1280 and the UE 1250, and RAP sub-layer configuration information or a combination thereof, may determine that data/signaling needs to be relayed between the UE 1250 and the base station 1280, and may determine that PC5 direct link connection establishment for relay transmission between the UE 1250 and the base station 1280 is necessary. In step 1253, the identification information of the UE 1250, which the target sidelink relay 1270 obtains from the base station 1280, may include at least one of an RNTI of the UE 1250 and a 2 nd destination layer ID of the UE 1250 or a combination thereof. The layer 2 destination layer ID of UE 1250 may be used for relay transmissions via UE 1250 and the previous service sidelink relay. If it is determined that the 2 nd layer ID needs to be updated when connected to the target sidelink relay 1270, the UE 1250 may perform a 2 nd layer ID update procedure using the target sidelink relay 1270.

Further, in step 1253, the base station 1280 may send the target sidelink relay 1270 sidelink SLRB configuration information for relay transmissions, which may be the same as the sidelink SLRB configuration information used by the UE 1250 for relay transmissions with the previously served sidelink relay. As another embodiment, in the case where the base station 1280 decides to change the sidelink SLRB configuration information for relay transmission between the target sidelink relay 1720 and the UE 1250, the base station 1280 may transmit the sidelink SLRB configuration information for sidelink relay transmission to the target sidelink relay 1270 and the UE 1250.

As another embodiment, the operation of the base station 1280 transmitting the sidelink SLRB configuration information for sidelink relay transmission to the target sidelink relay 1270 and the UE 1250 may be performed after: direct link setup required for relay transmission is completed at UE 1250 and target sidelink relay 1270 and a sidlinkiueinformation message is received requesting base station 1280 to allocate PC5 SLRB configuration information for sidelink relay transmission.

In step 1254, target sidelink relay 1270 may send an rrcrecon configuration complete message to base station 1280 in response.

In step 1255, target sidelink relay 1270 may perform a PC5 direct link connection establishment procedure with UE 1250. By triggering the target sidelink relay 1270 that receives the rrcrecon configuration message in step 1253, the ue 1250 and the target sidelink relay 1270 may perform a PC5 direct link setup procedure using V2X layer PC5-S signaling. The target sidelink relay 1270 may set the PC5-S signaling protocol cause to "relay path switch" or "link setup for indirect communication" and send a direct link setup request PC5-S signaling to the UE 1250. If the UE 1250 and the target sidelink relay 1270 have performed a PC5 direct link setup procedure for regular sidelink data transmission and reception, not for relay transmission, and maintained a PC5 direct link connection, the UE 1250 and the target sidelink relay 1270 may relay transmission using an existing PC5 direct link connection. In this case, the target sidelink relay 1270 may set the PC5-S signaling protocol cause to "relay path switch" or "link establishment for indirect communication" and send a direct link modification request PC5-S signaling to the UE 1250.

As another embodiment, in the case of relaying between UE 1250 and target sidelink relay 1270 using an established PC5 direct link, target sidelink relay 1270 may send PC5 RRC signaling (e.g., rrcrecon configuration sidelink) to UE 1250 indicating that a PC5 SLRB configuration for relaying is required. In addition, the ue 1250 and the target sidelink relay 1270 may also perform an SLRB configuration procedure using sidelink RRC signaling in step 1255. As another embodiment, in step 1255, the ue 1250 and the target sidelink relay 1270 may not perform the sidelink SLRB configuration procedure, but may perform the sidelink SLRB configuration procedure after acquiring the sidelink SLRB configuration information for the relay from the base station 1280.

In step 1256, target sidelink relay 1270 may send a sidelink information message to base station 1280 including at least one of or a combination of the following: a notification of a PC5 direct link connection establishment for relay transmission with the UE 1250, a notification of a PC5 SLRB configuration required for relay transmission with the UE 1250, a notification of side link transmission resource request information required for relay transmission to the UE 1250, and UE 1250 identification information. The identification information of the UE 1250 used in step 1256 may include a layer 2 ID of the UE 1250, or a unicast link ID and a target sidelink relay 1270 of the UE 1250, and the UE identification information may be used to distinguish the UE 1250 in a Relay Adaptation Protocol (RAP) sub-layer of the base station 1280 and the target sidelink relay 1270. In the case of using the layer 2 ID as the identification information of the UE 1250, the layer 2 ID may be used for relay transmission through the UE 1250 and the previous service side link relay. If it is determined that the 2 nd destination layer ID needs to be updated in the case of connection with the target sidelink relay 1270, the UE 1250 may perform a 2 nd destination layer ID update procedure using the target sidelink relay 1270. In step 1256, upon receiving a sidelink relay connection establishment message from target sidelink relay 1270 including sidelink relay connection establishment report, information about UE 1250 connected to target sidelink relay 1270 for sidelink relay connection, and the like, base station 1280 may determine whether target sidelink relay 1270 and UE 1250 need PC5 SLRB configuration information for sidelink relay transmission. In step 1257, the base station 1280 may send relay configuration information required for data/signaling relay transmissions between the UE 1250 and the base station 1280 to the target sidelink relay 1270 and to the RAP sublayer configuration information. When the base station 1280 transmits the relay configuration information or RAP sub-layer configuration information to the target sidelink relay 1270, the identification information of the UE 1250 reported by the target sidelink relay 1270 in the sidelinkiueinformation message of step 1256 may be contained. In step 1258, target sidelink relay 1270 may send an rrcr configuration complete message to base station 1280 in response to the rrcr configuration message of step 1257. Further, in step 1257, the base station 1280 may send the target sidelink relay 1270 sidelink SLRB configuration information for relay transmissions, which may be the same as the sidelink SLRB configuration information used by the UE 1250 for relay transmissions with the previously served sidelink relay.

As another embodiment, in case the base station 1280 decides to change the side link SLRB configuration information for relay transmission between the target side link relay 1270 and the UE 1250, the base station 1280 may transmit the side link SLRB configuration information for side link relay transmission to the target side link relay 1270 and the UE 1250. In step 1259, the ue 1250 and the target sidelink relay 1270 may exchange PC5 RRC signaling to check or update sidelink SLRB configuration information for relay transmissions. Checking the side link SLRB configuration information for relay transmission may correspond to: based on the side link SLRB configuration information that UE 1250 has configured with previously serving side link relay and is in use for relay transmissions, UE 1250 configures side link SLRB information for relay transmissions with target side link relay 1270. Updating the sidelink SLRB configuration information for relay transmission between the UE 1250 and the target sidelink relay 1270 may correspond to the following operations: the side link SLRB information used for relay transmission between the UE 1250 and the target side link relay 1270 is configured based on the side link SLRB configuration information newly obtained from the base station 1280. When the sidelink SLRB configuration for relaying transmission between the UE 1250 and the target sidelink relay 1270 is completed, the UE 1250 may transmit an rrcrecon configuration complete message to the base station 1280 through the target sidelink relay 1270 in order to report that the sidelink relay change is completed in step 1260.

In the case where the UE 1250 performs a sidelink relay change procedure to the target sidelink relay 1270 when performing a direct connection with the base station 1280, the UE 1250 may release Uu L1 (PHY) entity configuration, uu MAC entity configuration, and Uu RLC entity configuration information of the Uu DRB/SRB, which are configured for a direct connection with the base station 1280, but are not necessary for relay transmission with the target sidelink relay 1270. The UE 1250 may use Uu PDCP entity configuration, uu SDAP entity configuration, and Uu RRC entity configuration information with the base station 1280 even when connected with the target sidelink relay 1270 unless the base station 1280 indicates a change. UE 1250 may configure the PC 5L 1 (PHY) entity configuration, PC5MAC entity configuration, and PC5 RLC entity configuration information required for relay transmissions with target sidelink relay 1270.

In case the UE 1250 performs a sidelink relay change procedure to the target sidelink relay 1270 when performing a connection with the base station through the serving sidelink relay, the UE 1250 may perform an operation of releasing the PC5 direct link and connection setup and the SLRB configuration for relay transmission with the previous serving sidelink relay, which are no longer needed. PC5 direct link and connection setup and SLRB configuration, which should be used by UE 1250 and the previous serving sidelink relay for separate sidelink direct data transmission and reception instead of for relay transmission, can be continued to be used without being released. The operation procedure performed by the UE 1250 with the previous service side link relay for releasing the PC5 direct link and connection setup and SLRB configuration for relay transmission that are no longer needed is the same as the embodiment of fig. 9 or 10. The previous serving sidelink relay may release the RAP sublayer configuration information and the PC5 SLRB configuration information configured for the relay transmission of the UE 1250, and the operation procedures performed by the previous serving sidelink relay with the UE 1250 and the serving base station 1280 are shown in fig. 9 and 10 and fig. 11a and 11b, respectively.

Fig. 13 shows a sidelink relay change procedure of a UE in a case where the UE transmits and receives data/signaling with a base station through a relay connection of a sidelink relay while the UE is directly connected to a serving base station.

Referring to fig. 13, in step 1301, ue 1300 may receive an rrcrecon configuration message from serving base station 1340 indicating that a sidelink relay is changed from a relay connection of the sidelink relay to a direct connection with serving base station 1340. In step 1302, the ue 1300 may determine a sidelink relay change based on the rrcrecon configuration message of step 1301 and determine to perform a direct connection procedure to the serving base station 1340. The UE may perform a synchronization acquisition and random access procedure with the serving base station 1340 and process Uu RRC configuration information, cell group configuration information, etc., necessary for a direct connection with the serving base station 1340 based on the configuration information of the rrcrecon configuration message of step 1301. For example, the UE may configure a Uu L1 entity, a Uu MAC entity, and a Uu L1 entity with the serving base station 1340 based on Uu L1 (PHY) entity configuration information, uu MAC entity configuration information, and Uu RLC entity configuration information for direct connection with the serving base station 1340. In case of performing the random access procedure for the serving base station 1340, the UE 1300 may perform at least one of a contention-free random access procedure, a contention-based random access procedure, a 2-step random access procedure, and a 4-step random access procedure, or a combination thereof. Even in the case of transmitting and receiving data/signaling with the serving base station 1340 through a relay connection with a sidelink relay, if the serving base station 1340 does not allocate Uu RRC entity configuration information, uu SDAP entity configuration information, and Uu PDCP entity configuration information changed through the rrcrecon configuration message of step 1301, since the UE 1300 has already configured Uu RRC entity, uu SDAP entity, and Uu PDCP service with the serving base station 1340, the UE 1300 can maintain the existing entity configuration information and use it for data/signaling transmission and reception through a direct connection with the base station 1340. In step 1303, ue 1300 may send an rrcrecon configuration complete message to serving base station 1340 using the direct connection configuration information. The UE 1300 may perform operations of releasing PC5 direct link and connection setup and SLRB configuration for relay transmission with the previous service side link relay that is no longer needed. PC5 direct link and connection setup and SLRB configuration, which should be used by UE 1300 and the previously serving sidelink relay for separate sidelink direct data transmission and reception instead of for relay transmission, can be continued to be used without being released. The operation procedure performed by the UE 1300 with the previous service side link relay for releasing PC5 direct link and connection establishment and SLRB configuration for relay transmission that are no longer needed is the same as the embodiment of fig. 9 or 10. The previous serving sidelink relay may release this RAP sublayer configuration information and PC5 SLRB configuration information configured for relay transmission to the UE 1300, and the operational procedures performed by the previous serving sidelink relay with the UE 1300 and the serving base station 1340 are shown in fig. 9 and 10 and fig. 11a and 11b, respectively.

Next, a case where the UE performs a sidelink relay change procedure to a neighboring base station other than the serving base station will be described with reference to fig. 14 and 15. The embodiment of fig. 14 corresponds to a case where the UE changes the sidelink relay connection with the serving base station to a direct connection with the target base station. The embodiment of fig. 15 corresponds to the case where the UE changes the sidelink relay connection with the serving base station to the connection with the sidelink relay of the target base station.

Referring to fig. 14, in step 1402, the ue 1400 may acquire an rrcrecon configuration message including side link relay change configuration information indicating direct connection to the target base station 1430 from the serving base station 1420 when changing the side link relay connection with the serving base station to direct connection with the target base station. In step 1401, the serving base station 1420 and the target base station 1430 may perform a procedure for exchanging inter-node messages for a sidelink relay change, so that the UE 1400 acquires configuration information necessary for establishing a direct connection with the target base station 1430 in the rrcrecon configuration message in step 1402. The inter-node message of step 1401 may be used to exchange not only identification information and sidelink relay support capability information of the UE 1400 but also random access configuration information, uu RRC entity configuration information, uu SDAP entity information, uu PDCP entity information, uu RLC entity information, uu MAC entity information, uu L1 (PHY) entity information, etc. that the UE 1400 may use for direct connection with the target base station 1430. In step 1403, the ue 1400 may determine that connection to the target base station 1430 is required and perform an access procedure to the target base station 1430. For the target base station 1430, the ue 1400 may process a synchronization acquisition procedure, a random access procedure (based on at least one of contention, contention-free, 2-step RACH, and 4-step RACH, or a combination thereof), a Uu RRC entity configuration, a Uu SDAP entity configuration, a Uu PDCP entity configuration, a Uu RLC entity configuration, a Uu MAC entity configuration, a Uu L1 (PHY) entity configuration information, and perform a Uu RRC entity configuration, a Uu SDAP entity configuration, a Uu PDCP entity configuration, a Uu RLC entity configuration, a Uu MAC entity configuration, and a Uu L1 (PHY) entity configuration with the target base station 1430. In step 1404, the ue 1400 may send an rrcrecon configuration complete message to the target base station 1430. For signaling/data relay transmissions with the serving base station 1420, the UE 1400 may release the PC5 direct link setup with the sidelink relay 1410. The PC5 direct link setup release procedure for relay transmission performed by the UE 1400 and the sidelink relay 1410 is the same as the embodiment of fig. 9 (the PC5 direct link setup release procedure for relay transmission triggered based on the UE) or fig. 10 (the PC5 direct link setup release procedure for relay transmission triggered based on the sidelink relay). In the case of continuing the procedure of fig. 10, the serving base station 1420 may transmit an rrcrecon configuration message to the sidelink relay 1410 indicating that relay connection with the UE 1400 is not required, and instruct release of RAP configuration for relay transmission with the UE 1400, release of relay configuration for the UE 1400, and release of sidelink configuration for relay transmission with the UE 1400. An implementation in which serving base station 1420 sends an rrcrecon configuration message to sidelink relay 1410 may include the following: the serving base station 1420 transmits the rrcrecon configuration message to the UE 1400 in step 1402 and transmits the rrcrecon configuration message alone to the sidelink relay 1410 to notify the relay configuration release; or the UE 1400 transmits an rrcrecon configuration complete message to the target base station 1430 in step 1404, the target base station 1430 transmits an inter-node message to the serving base station 1420 to inform the UE 1400 of the completion of the handover and sidelink relay change procedure, and the serving base station 1420 transmits an rrcrecon configuration message to the serving sidelink relay 1410 to inform the relay configuration release.

Referring to fig. 15, in step 1502, the ue 1500 may acquire an rrcrecon configuration message from the serving base station 1530 in case of a direct connection configuration with the serving base station 1530 or acquire an rrcrecon configuration message from the serving sidelink relay including sidelink relay change configuration information indicating that the target base station 1540 is connected to the sidelink relay 1550 in case of performing data/signaling transmission and reception with the serving base station 1530 through the sidelink relay connected to the sidelink relay. For Uu configuration information with the target base station 1540 and sidelink relay connection configuration information with the target sidelink relay 1550 for data/signaling transmission and reception with the target base station 1540 in the rrcrecon configuration message delivered to the UE 1500 in step 1502, the serving base station 1530 and the target base station 1501 may perform a procedure for exchanging inter-node messages for sidelink relay change in step 1501. The inter-node message of step 1501 may be used to exchange not only identification information and side link relay support capability information of the UE 1500, but also Uu RRC entity configuration information, uu SDAP entity information, and Uu PDCP entity information between the UE 1500 and the target base station 1540, and PC 5L 1 (PHY) entity information, PC5MAC entity information, and PC5 RLC entity information between the UE and the target side link relay 1550. In step 1503, the ue 1500 may determine that connection to the target base station 1540 and the target sidelink relay 1550 is required and perform an access procedure with the target base station 1540 and the target sidelink relay 1550. The target base station 1540 may inform the target sidelink relay 1550 of the sidelink direct link setup required for relay with the UE 1500 through the rrcrecconfiguration message in step 1504 or the rrcrecfiguration complete message in step 1505. During steps 1504 and 1505, the target sidelink relay 1550 may obtain at least one of information of the UE 1500, relay configuration information necessary for relay transmission between the target base station 1540 and the UE 1500, and RAP sub-layer configuration information, or a combination thereof, from the target base station 1540.

For example, in step 1506, the ue 1500 may determine that a PC5 direct link establishment procedure with the target sidelink relay 1550 is necessary to establish a connection with the target base station 1540 for data/signaling transmission and reception, and perform a PC5 direct link connection establishment procedure with the target sidelink relay 1550. By triggering UE 1500, UE 1500 and target side link relay 1550 may perform a PC5 direct link setup procedure using V2X layer PC5-S signaling. UE 1500 may set the PC5-S signaling protocol cause to "relay path switch" or "link setup for indirect communication" and send a direct link setup request PC5-S signaling to target sidelink relay 1550. If the UE 1500 and the target sidelink relay 1550 have performed a PC5 direct link setup procedure for regular sidelink data transmission and reception instead of for relay transmission and maintained a PC5 direct link connection, the UE 1500 and the target sidelink relay 1550 may relay transmission using the existing PC5 direct link connection. In this case, the UE 1500 may set the PC5-S signaling protocol cause to "relay path switch" or "link establishment for indirect communication", and send a direct link modification request PC5-S signaling to the target sidelink relay 1550. As another embodiment, in the case of relaying between the UE 1500 and the target sidelink relay 1550 using an already established PC5 direct link, the UE 1500 may send a PC5 SLRB configuration PC5 RRC signaling (e.g., rrcrecon configuration sidelink) to the target sidelink relay 1550 indicating that a PC5 SLRB configuration for relaying is required. In addition, the ue 1500 and the target sidelink relay 1550 may also perform the SLRB configuration procedure using sidelink RRC signaling in step 15063. As another embodiment, in step 1506, the ue 1500 and the target sidelink relay 1550 may not perform the sidelink SLRB configuration procedure, but may perform the sidelink SLRB configuration procedure after acquiring sidelink SLRB configuration information for the relay from the target base station 1540.

Through the process of step 1506, the target sidelink relay 1550 may determine that it is required to relay data/signaling between the UE 1500 and the target base station 1540, and may obtain information of the UE 1500. In step 1508, target sidelink relay 1550 may send a sidlinkueinformation message to target base station 1540 reporting that relay transmissions to UE 1500 are required. The sidlinkueinformation message of step 1508 may include at least one of identification information of the UE 1500, information indicating that SLRB configuration in relay transmission of the UE 1500 is required, and side link transmission resource request information necessary for relay transmission of the UE 1500, or a combination thereof. The identification information of the UE 1500 used in step 1508 may include a layer 2 layer ID of the UE 1500, or a unicast link ID of the UE 1500 and the target sidelink relay 1550, and the UE identification information may be used to distinguish the UE 1500 in a Relay Adaptation Protocol (RAP) sublayer of the target base station 1540 and the target sidelink relay 1550. In the case of using the layer 2 ID as the identification information of the UE 1500, the layer 2 ID may be used for relay transmission with the previous service side link relay through the UE 1500. If it is determined that the 2 nd layer ID needs to be updated in the case of connection with the target side link relay 1550, the UE 1500 may perform a 2 nd layer ID update procedure using the target side link relay 1550. In step 1509, the target base station 1540 may send relay configuration information required for data/signaling relay transmission between the UE 1500 and the target base station 1540 to the target sidelink relay 1550 and send RAP sub-layer configuration information. When the target base station 1540 transmits the relay configuration information or RAP sub-layer configuration information to the target sidelink relay 1550, the identification information of the UE 1500 reported by the target sidelink relay 1550 in the sidlinkiueinformation message of step 1508 may be included. In step 1510, the target sidelink relay 1550 may send a rrcr configuration complete message to the target base station 1540 in response to the rrcr configuration message of step 1509. Further, the target base station 1540 may transmit the sidelink SLRB configuration information for relay transmission to the target sidelink relay 1550 in step 1509. In step 1511, the ue 1500 and the target sidelink relay 1550 may exchange PC5 RRC signaling of sidelink SLRB configuration information for relay transmission. The side link SLRB configuration information for relay transmission may include at least one of PC 5L 1 (PHY) entity configuration information, PC5MAC entity configuration information, and PC5 RLC entity configuration information, or a combination thereof.

As another example, in step 1506, the target sidelink relay 1550 may determine that a PC5 direct link establishment procedure with the UE 1500 is necessary to establish a connection for data/signaling transmission and reception between the target base station 1540 and the UE 1500, and perform the PC5 direct link connection establishment procedure with the UE 1500. By triggering the target sidelink relay 1550, the target sidelink relay 1550 may perform a PC5 direct link connection establishment procedure with the UE 1500 in step 1506. By triggering the target sidelink relay 1550 that receives the rrcrecon configuration message at step 1504, the ue 1500 and the target sidelink relay 1550 may perform a PC5 direct link setup procedure using V2X layer PC5-S signaling. The target sidelink relay 1550 may set the PC5-S signaling protocol cause to "relay path switch" or "link establishment for indirect communication" and send a direct link establishment request PC5-S signaling to the UE 1500. If the UE 1500 and the target sidelink relay 1550 have performed a PC5 direct link setup procedure for regular sidelink data transmission and reception, not for relay transmission, and maintain a PC5 direct link connection, the UE 1500 and the target sidelink relay 1550 may relay transmission using the existing PC5 direct link connection. In this case, the target sidelink relay 1550 may set the PC5-S signaling protocol cause to "relay path switch" or "link establishment for indirect communication", and send a direct link modification request PC5-S signaling to the UE 1500. As another embodiment, in the case of relaying between the UE 1500 and the target sidelink relay 1550 using an already established PC5 direct link, the target sidelink relay 1550 may send PC5 RRC signaling (e.g., rrcrecon configuration sidelink) to the UE 1500 indicating that a PC5 SLRB configuration for relaying is required. In addition, the ue 1500 and the target sidelink relay 1550 may also perform the SLRB configuration procedure using sidelink RRC signaling in step 1506. As another embodiment, in step 1506, the ue 1500 and the target sidelink relay 1550 may not perform the sidelink SLRB configuration procedure, but may perform the sidelink SLRB configuration procedure after acquiring sidelink SLRB configuration information for the relay from the target base station 1540.

In step 1507, the target sidelink relay 1550 may determine sidelink SLRB configuration information needed for relay transmission with the UE 1500, and in step 1508, may send a sidelink ueinformation message to the target base station 1540, the message including at least one of a notification of PC5 direct link connection establishment for relay transmission with the UE 1500, a notification of PC5 SLRB configuration needed for relay transmission with the UE 1500, sidelink transmission resource request information needed for relay transmission to the UE 1500, and a notification of identification information of the UE 1500, or a combination thereof. The identification information of the UE 1500 used in step 1508 may include a layer 2 layer ID of the UE 1500, or unicast link IDs of the UE 1500 and the target side link relay 1550, and the UE identification information may be used to distinguish the UE 1500 in a Relay Adaptation Protocol (RAP) sublayer of the target base station 1540 and the target side link relay 1550. In the case of using the layer 2 ID as the identification information of the UE 1500, the layer 2 ID may be used for relay transmission with the previous service side link relay through the UE 1500. If it is determined that the 2 nd layer ID needs to be updated in the case of connection with the target side link relay 1550, the UE 1500 may perform a 2 nd layer ID update procedure using the target side link relay 1550. Upon receiving the sidelink relay connection establishment report, information about the UE 1500 connected to the target sidelink relay 1550 for sidelink relay connection, and the like sidelink ueinformation message from the target sidelink relay 1550 in step 1508, the target base station 1540 may determine whether the target sidelink relay 1550 and the UE 1500 need PC5 SLRB configuration information for sidelink relay transmission. In step 1509, the target base station 1540 may send relay configuration information required for data/signaling relay transmission between the UE 1500 and the target base station 1540 to the target sidelink relay 1550 and send RAP sub-layer configuration information. When the target base station 1540 transmits the relay configuration information or RAP sub-layer configuration information to the target sidelink relay 1550, the identification information of the UE 1500 reported by the target sidelink relay 1550 in the sidlinkiueinformation message of step 1508 may be included. In step 1510, the target sidelink relay 1550 may send a rrcr configuration complete message to the target base station 1540 in response to the rrcr configuration message of step 1509. Further, the target base station 1540 may transmit the sidelink SLRB configuration information for relay transmission to the target sidelink relay 1550 in step 1509. In step 1511, the ue 1500 and the target sidelink relay 1550 may exchange PC5RRC signaling of sidelink SLRB configuration information for relay transmission. The side link SLRB configuration information for relay transmission may include at least one of PC 5L 1 (PHY) entity configuration information, PC5MAC entity configuration information, and PC5 RLC entity configuration information, or a combination thereof.

Further, the UE 1500 may process the Uu RRC entity configuration, the Uu SDAP entity configuration, and the Uu PDCP entity configuration information with the target base station 1540, and perform the Uu RRC entity configuration, the Uu SDAP entity configuration, and the Uu PDCP entity configuration with the target base station 1540. When the configuration of the PC 5L 1 (PHY) entity, the PC5 MAC entity, and the PC5 RLC entity is completed through the sidelink SLRB configuration for relay transmission between the UE 1500 and the target sidelink relay 1550, and the configuration of the Uu RRC entity, the Uu SDAP entity, and the Uu PDCP entity with the target base station 1540 is completed, the UE 1500 may transmit an rrcrecon configuration complete message to the target base station 1540 through the target end in step 1512 to report completion of handover and sidelink relay change.

In the case of performing a sidelink relay change procedure from connecting to the serving sidelink relay to connecting to the target sidelink relay 1550, the UE 1500 may release the PC5 direct link established with the sidelink relay for signaling/data relay transmission with the serving base station 1530. The PC5 direct link setup release procedure for relay transmission performed by the UE 1500 and the sidelink relay is the same as the embodiment of fig. 9 (the PC5 direct link setup release procedure for relay transmission triggered based on the UE) or fig. 10 (the PC5 direct link setup release procedure for relay transmission triggered based on the sidelink relay). In the case of performing the procedure of fig. 10, the serving base station 1530 may transmit an rrcrecon configuration message indicating that relay connection with the UE 1500 is not required to the sidelink relay, and instruct release of a RAP configuration for relay transmission with the UE 1500, release of a relay configuration for the UE 1500, and release of a sidelink configuration for relay transmission with the UE 1500. An implementation of serving base station 1530 sending rrcrecon configuration message to a sidelink relay may include the following cases: the serving base station 1530 transmits the rrcrecon configuration message to the UE 1500 in step 1502 to relay the rrcrecon configuration message alone to the sidelink to notify the relay configuration release; or the UE 1500 transmits an rrcrecon configuration complete message to the target base station 1540 in step 1512, the target base station 1540 transmits an inter-node message to the serving base station 1530 to inform the UE 1500 of the completion of the handover and the side link relay change procedure, and the serving base station 1530 transmits an rrcrecon configuration message to the serving side link relay to inform the relay configuration release.

In case of performing handover to change a serving cell (e.g., change connection to a target cell according to RRC reconfiguration with synchronization), the UE may perform PDCP entity re-establishment and RLC entity re-establishment with the target cell. According to embodiments of the present disclosure, the following will be described: the UE processes the PDCP entity and the RLC entity with the target base station or target sidelink relay when the UE changes from a direct connection with the base station to a direct connection with the sidelink relay, or when the UE changes from a direct connection with the sidelink relay to a direct connection with the base station.

In case that the UE is directly connected to the base station, the UE may configure a Uu SDAP entity and a Uu PDCP entity with the base station, and may configure a Uu RLC entity and a Uu MAC entity with the base station. In case that the UE is connected to the base station through the side link relay, the UE may configure the Uu SDAP entity and the Uu PDCP entity with the base station, and may configure the PC5 RLC entity and the PC5 MAC entity with the side link relay. For example, when the UE changes the path from the direct connection with the base station to the connection with the sidelink relay, the UE may maintain the Uu SDAP entity and the Uu PDCP entity with the base station, but the PC5 RLC entity and the PC5 MAC entity may be configured by the sidelink relay instead of the Uu RLC entity and the Uu MAC entity with the base station. For example, when the UE changes from being connected with the base station through the sidelink relay to being directly connected with the base station, the UE may maintain the Uu SDAP entity and the Uu PDCP entity with the base station, but may configure the Uu RLC entity and the Uu MAC entity with the base station instead of configuring the PC5 RLC and PC5 MAC entities with the sidelink relay. For example, when the UE changes the path from the connection directly with the base station a or connected to the base station a through the sidelink relay to the connection directly with the base station B or connected to the base station B through the sidelink relay, the UE may configure (1) the Uu SDAP entity and the Uu PDCP entity for the base station B and the Uu RLC entity and the Uu MAC entity for the base station B or (2) the Uu SDAP entity and the Uu PDCP entity for the base station B and the Uu RLC entity and the Uu MAC entity connected to the base station B and the sidelink relay.

A scheme in which the UE processes the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity according to the path change configuration message will be described.

In one embodiment, in case the UE acquires a path change configuration message indicating to connect directly from the base station to the connection with the sidelink relay or the UE acquires a path change configuration message indicating to connect directly from the sidelink relay to the base station, the path change configuration message may include configuration information for the UE to process at least one of the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity, or a combination thereof, as follows.

(A) In case the UE performs path change within the same base station

When the UE performs relay connection from the sidelink to the direct connection with the base station, random access processing with the PCell/PSCell, uu MAC reset configuration or Uu MAC configuration, uu RLC setup (including PC5 logical channels and Uu logical channels mapped thereto) configuration, and PDCP data recovery (RLC AM mode only DRB) configuration may be indicated by the layer 2 indicator. When the UE performs relay connection from the side link to the direct connection with the base station, the PC5 MAC reset configuration and the PC5 RLC entity release configuration (including the PC5 logical channels and Uu logical channels mapped thereto) may be indicated by a layer 2 indicator. The UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity based on the indication of the configuration information when changing from the relay connection with the side link to the direct connection with the base station.

The Uu MAC reset configuration, uu RLC release configuration (including PC5 logical channels and Uu logical channels mapped thereto), and PDCP data recovery (RLC AM mode only DRB) configuration may be indicated by layer 2 indicators when the UE performs a direct connection from the base station to the sidelink relay connection. The PC5 MAC reset configuration and the PC5 RLC setup configuration (including the PC5 logical channels and Uu logical channels mapped thereto) may be indicated by a layer 2 indicator when the UE performs a direct connection from the base station to the sidelink relay connection. The UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity based on the indication of the configuration information when changing from the relay connection with the side link to the direct connection with the base station.

In another embodiment, in case the UE acquires a path change configuration message indicating direct connection from the base station to the side link relay connection or acquires a path change configuration message indicating direct connection from the side link relay connection to the base station, the path change configuration message may include configuration information for the UE to process at least one of Uu PDCP entity, uu RLC entity, uu MAC entity, PC5 RLC entity, and PC5 MAC entity, or a combination thereof, as follows.

The random access process with PCell/PSCell, uu MAC reset configuration or Uu MAC configuration, uu RLC setup (including PC5 logical channels and Uu logical channels mapped thereto) configuration, and Uu PDCP reestablishment with key refreshing (when the base station determines that the security keys used in Uu PDCP need to be changed) configuration are indicated by layer 2 indicators when the UE performs relay connection from the sidelink to the direct connection with the base station. When the UE performs relay connection from the sidelink to the direct connection with the base station, the layer 2 indicator may indicate a PC5MAC reset configuration and a PC5 RLC entity release configuration (including a PC5 logical channel and Uu logical channels mapped thereto). The UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5MAC entity based on the indication of the configuration information while changing from the connection with the sidelink relay to the direct connection with the base station.

The Uu MAC reset configuration, uu RLC release configuration (including PC5 logical channels and Uu logical channels mapped thereto), and Uu PDCP re-establishment with key flushing (when the base station determines that the security key used in Uu PDCP needs to be changed) may be indicated by a layer 2 indicator when the UE performs a relay connection from a direct connection with the base station to a side link. The PC5MAC reset configuration and the PC5 RLC setup configuration (including the PC5 logical channels and Uu logical channels mapped thereto)) may be indicated by a layer 2 indicator when the UE performs a direct connection from the base station to the sidelink relay connection. The UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5MAC entity based on the indication of the configuration information when changing from the direct connection with the base station to the relay connection with the side link.

(B) In case the UE performs a path change from base station a to base station B

When the UE performs relay connection from the sidelink in the base station a to the direct connection with the base station B, random access processing with the PCell/PSCell, uu MAC reset configuration or Uu MAC configuration, uu RLC setup (including PC5 logical channels and Uu logical channels mapped thereto) configuration, and Uu PDCP reestablishment with a key refresh configuration may be indicated by a layer 2 indicator. The PC5 MAC reset configuration or PC5 MAC release configuration, and the PC5 RLC entity release configuration (including the PC5 logical channels and Uu logical channels mapped thereto) may be indicated by a layer 2 indicator when the UE performs a relay connection from a sidelink in base station a to a direct connection with base station B. When changing from the sidelink relay connection with the base station a to the direct connection with the base station B, the UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity based on the indication of the configuration information.

The Uu MAC reset configuration, uu RLC release configuration (including PC5 logical channels and Uu logical channels mapped thereto)), and Uu PDCP re-establishment with key refresh configuration may be indicated by a layer 2 indicator when the UE performs a relay connection from a direct connection with base station a to a sidelink in base station B. The PC5 MAC reset configuration or PC5 MAC release configuration, and the PC5 RLC setup configuration (including the PC5 logical channels and Uu logical channels mapped thereto) may be indicated by a layer 2 indicator when the UE performs a relay connection from directly connecting with base station a to a sidelink in base station B. The UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity based on the indication of the configuration information when changing from the direct connection with the base station a to the sidelink relay connection in the base station B.

In another embodiment, in case the UE acquires a path change configuration message indicating to connect directly from the side link relay connected to the base station B to the base station a or acquires a path change configuration message indicating to connect directly from the side link relay connected to the base station B to the base station a, the path change configuration message may include configuration information for the UE to process at least one of Uu PDCP entity, uu RLC entity, uu MAC entity, PC5 RLC entity, and PC5 MAC entity or a combination thereof, as shown below.

When the UE performs relay connection from the sidelink in the base station a to the direct connection with the base station B, random access processing with PCell/PSCell, uu MAC reset configuration or Uu MAC configuration, uu RLC setup (including PC5 logical channels and Uu logical channels mapped thereto) configuration, and Uu PDCP reestablishment with key refreshing configuration may be indicated by a layer 2 indicator. The PC5 MAC reset configuration or PC5 MAC release configuration, and the PC5 RLC entity release configuration (including the PC5 logical channels and Uu logical channels mapped thereto) may be indicated by a layer 2 indicator when the UE performs a relay connection from a sidelink in base station a to a direct connection with base station B. When changing from the sidelink relay connection with the base station a to the direct connection with the base station B, the UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity based on the indication of the configuration information.

The Uu MAC reset configuration, uu RLC release configuration (including PC5 logical channels and Uu logical channels mapped thereto)), and Uu PDCP re-establishment with key refresh configuration may be indicated by a layer 2 indicator when the UE performs a relay connection from a direct connection with base station a to a sidelink in base station B. When the UE performs a relay connection from directly connecting with base station a to a sidelink in base station B, the PC5 MAC reset configuration and the PC5 RLC setup configuration (including the PC5 logical channels and Uu logical channels mapped thereto) may be indicated by a layer 2 indicator. The UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity based on the indication of the configuration information when changing from the direct connection with the base station a to the sidelink relay connection in the base station B.

In one embodiment, a Uu MAC reset configuration, a Uu RLC re-establishment (including Uu logical channels and PC5 logical channels mapped thereto) configuration, and a Uu PDCP re-establishment with a key refresh configuration may be indicated by a layer 2 indicator when the UE performs a relay connection from a sidelink in base station a to a sidelink relay connection in base station B. When the UE performs a relay connection from a sidelink with base station a to a sidelink with base station B, the PC5 MAC reset configuration and the PC5 RLC re-establishment configuration (including Uu logical channels and PC5 logical channels mapped thereto) may be indicated by a layer 2 indicator. The UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity based on the indication of the configuration information when changing from the sidelink relay connection with the base station a to the sidelink relay connection with the base station B.

In another embodiment, uu PDCP re-establishment with a key refresh configuration may be indicated by a layer 2 indicator when the UE performs a relay connection from a side link with base station a to a side link with base station B. When the UE performs a relay connection from a sidelink with base station a to a sidelink with base station B, the PC5 MAC reset configuration and the PC5 RLC re-establishment configuration (including Uu logical channels and PC5 logical channels mapped thereto) may be indicated by a layer 2 indicator. The UE may process the Uu PDCP entity, the Uu RLC entity, the Uu MAC entity, the PC5 RLC entity, and the PC5 MAC entity based on the indication of the configuration information when changing from the sidelink relay connection with the base station a to the sidelink relay connection with the base station B.

When the UE changes the path from the direct connection with the base station to the sidelink relay or from the direct connection with the sidelink relay to the direct connection with the base station, the Uu PDCP entity with the base station configured by the UE may not need to update the security key used in the PDCP layer and perform a security key refresh operation, and the Uu PDCP entity may perform an operation of restoring the PDCP data, thereby restoring the PDCP PDU loss that may occur during the path change. In this case, when the UE obtains a path change indication message indicating to connect directly from the base station to connect directly to the sidelink relay, or when the UE obtains a path change indication message indicating to connect directly from the sidelink relay to the base station, and when PDCP data recovery of the PDCP entity is configured in the path change indication message, an operation for the UE to process PDCP data PDU retransmission is as follows.

If it is determined that status reporting is enabled in an RRC configuration message including a Data Radio Bearer (DRB) configuration, the UE may send a PDCP status report message to the base station in case of a path change from a direct connection with the base station to a sidelink relay connection or in case of a path change from a direct connection with the sidelink relay connection to a direct connection with the base station for an RLC AM mode DRB in which status reporting is enabled. The PDCP status report message may include information regarding downlink PDCP data PDUs received by the UE from the base station. Further, for RLC AM mode DRBs in which status reporting requirement is enabled in an RRC configuration message including a DRB configuration, the UE may receive a PDCP status report message from the base station, and the PDCP status report message may contain information about uplink PDCP data PDUs transmitted by the UE to the base station. The UE may delete PDCP data PDUs indicated to be transmitted without error according to the information of the received PDCP status report message, and may retransmit PDCP data PDUs indicated to have not been transmitted correctly. That is, when the UE changes from the relay connection with the sidelink to the direct connection with the base station, the UE may retransmit the unsuccessfully transferred PDCP data PDU by referring to a COUNT value of PDCP data PDUs indicated as unsuccessfully transferred in a PDCP status report message among PDCP data PDUs transmitted by the PC5 RLC entity in the released AM mode. Alternatively, when the UE changes from direct connection with the base station to relay connection with the sidelink, the UE may retransmit the unsuccessfully delivered PDCP data PDU by referring to a COUNT value of PDCP data PDUs indicated as unsuccessfully delivered in a PDCP status report message among PDCP data PDUs transmitted by the Uu RLC entity in the released AM mode.

The methods according to the embodiments set forth in the claims or specification of the present disclosure may be implemented in hardware, software, or a combination thereof.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in the electronic device. The one or more programs include instructions for causing the electronic device to perform the methods according to the embodiments described in the claims or specification of the present disclosure.

Such programs (software modules, software) may be stored in random access memory, non-volatile memory, including flash memory, read-only memory (ROM), electrically Erasable Programmable ROM (EEPROM), magnetic disk storage, compact disk ROM (CD-ROM), digital Versatile Disks (DVD), other types of optical storage, or magnetic cassettes. Alternatively, such a program may be stored in a memory configured with a combination of some or all of the memory. Furthermore, each configuration memory may be included in a complex manner.

Further, the program may be stored in a connectable storage device that can be accessed through a communication network configured by a communication network such as the internet, an intranet, a Local Area Network (LAN), a Wide Area Network (WAN), or a Storage Area Network (SAN), or a combination thereof. Such a storage device may access devices implementing embodiments of the present disclosure through an external port. Further, a separate storage device on the communication network may access the device implementing embodiments of the present disclosure.

In the specific embodiments of the disclosure above, the components included in the disclosure are represented in the singular or the plural depending on the specific embodiment presented. However, for convenience of description, a singular or plural expression is appropriately selected for the presented case, and the present disclosure is not limited to a singular or plural component, and the component may be configured in the singular even if the component is expressed in the plural, or the component may be configured in the plural even if the component is expressed in the singular.

Although specific embodiments have been described in the detailed description of the disclosure, various modifications are possible without departing from the scope of the disclosure. Thus, the scope of the disclosure should not be limited to the described embodiments, but should be defined by the claims set forth below and the equivalents of the claims.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising:

receiving measurement configuration information for changing a path from a base station, the measurement configuration information including at least one of frequency information of at least one neighbor cell to be measured or resource information of at least one candidate sidelink relay terminal to be measured;

Performing measurements on the at least one neighboring cell or the at least one candidate sidelink relay terminal based on the measurement configuration information; and

and sending the measurement result to the base station.

2. The method of claim 1, wherein the resource information of the at least one candidate sidelink relay terminal comprises a physical cell identifier, PCI, of a serving cell of the at least one candidate sidelink relay terminal.

3. The method of claim 1, wherein, in the case where the measurement result includes a measurement result of the at least one candidate sidelink relay terminal, the measurement result includes at least one of: the identification information of the at least one candidate sidelink relay terminal, the identification information of the serving cell of the at least one candidate sidelink relay terminal, or the measurement result value of the at least one candidate sidelink relay terminal.

4. The method of claim 1, further comprising:

receiving a message indicating handover or change of a sidelink relay terminal from the base station;

releasing a PC5 radio resource control, RRC, connection with the service sidelink relay terminal in case the terminal is connected to the service sidelink relay terminal; and

In case that the terminal is connected to the serving base station, a PC5 RRC connection with the target sidelink relay terminal is configured.

5. A method performed by a base station in a wireless communication system, the method comprising:

transmitting measurement configuration information for changing a path to a terminal, the measurement configuration information including at least one of frequency information of at least one neighbor cell to be measured or resource information of at least one candidate sidelink relay terminal to be measured;

receiving from the terminal a measurement result of the at least one neighboring cell or the at least one candidate sidelink relay terminal based on the measurement configuration information; and

based on the measurement results, it is determined to switch the terminal or connect the terminal to a target sidelink relay terminal.

6. The method of claim 5, wherein the resource information of the at least one candidate sidelink relay terminal comprises a physical cell identifier, PCI, of a serving cell of the at least one candidate sidelink relay terminal.

7. The method of claim 5, wherein, in the case where the measurement result includes a measurement result of the at least one candidate sidelink relay terminal, the measurement result includes at least one of: the identification information of the at least one candidate sidelink relay terminal, the identification information of the serving cell of the at least one candidate sidelink relay terminal, or the measurement result value of the at least one candidate sidelink relay terminal.

8. The method of claim 5, further comprising:

upon determining to connect the terminal to the target sidelink relay terminal based on the received measurement result, a message including configuration information for sidelink relay is transmitted to the target sidelink relay terminal, the message including at least one of identification information of the terminal, sidelink relay Uu configuration information, or sidelink relay radio link control RLC configuration information.

9. A terminal in a wireless communication system, the terminal comprising:

a transceiver; and

a controller coupled with the transceiver and configured to: receiving measurement configuration information for changing a path from a base station, the measurement configuration information including at least one of frequency information of at least one neighbor cell to be measured or resource information of at least one candidate sidelink relay terminal to be measured; performing measurements on the at least one neighboring cell or the at least one candidate sidelink relay terminal based on the measurement configuration information; and transmitting the measurement result to the base station.

10. The terminal of claim 9, wherein the resource information of the at least one candidate sidelink relay terminal comprises a physical cell identifier, PCI, of a serving cell of the at least one candidate sidelink relay terminal.

11. The terminal of claim 9, wherein, in the case where the measurement result includes a measurement result of the at least one candidate sidelink relay terminal, the measurement result includes at least one of: the identification information of the at least one candidate sidelink relay terminal, the identification information of the serving cell of the at least one candidate sidelink relay terminal, or the measurement result value of the at least one candidate sidelink relay terminal.

12. The terminal of claim 9, wherein the controller is further configured to: receiving a message indicating handover or change of a sidelink relay terminal from the base station; releasing a PC5 radio resource control, RRC, connection with the service sidelink relay terminal in case the terminal is connected to the service sidelink relay terminal; and configuring a PC5 RRC connection with the target sidelink relay terminal in a case that the terminal is connected to the serving base station.

13. A base station in a wireless communication system, the base station comprising:

a transceiver; and

a controller coupled with the transceiver and configured to: transmitting measurement configuration information for changing a path to a terminal, the measurement configuration information including at least one of frequency information of at least one neighbor cell to be measured or resource information of at least one candidate sidelink relay terminal to be measured; receiving from the terminal a measurement result of the at least one neighboring cell or the at least one candidate sidelink relay terminal based on the measurement configuration information; and determining to switch the terminal or connect the terminal to a target sidelink relay terminal based on the measurement result.

14. The base station of claim 13, wherein the resource information of the at least one candidate sidelink relay terminal comprises a physical cell identifier, PCI, of a serving cell of the at least one candidate sidelink relay terminal, and

in the case that the measurement result includes a measurement result of the at least one candidate sidelink relay terminal, the measurement result includes at least one of: the identification information of the at least one candidate sidelink relay terminal, the identification information of the serving cell of the at least one candidate sidelink relay terminal, or the measurement result value of the at least one candidate sidelink relay terminal.

15. The base station of claim 13, wherein the controller is further configured to: upon determining to connect the terminal to the target sidelink relay terminal based on the received measurement result, a message including configuration information for sidelink relay is transmitted to the target sidelink relay terminal, the message including at least one of identification information of the terminal, sidelink relay Uu configuration information, or sidelink relay radio link control RLC configuration information.