Method and apparatus for relay selection and reselection in wireless communication system

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). The present disclosure provides a method performed by a first node in a communication system, the method comprising: determining cell related information of the first node, and transmitting, to a second node, the cell-related information and first information, wherein the first information includes at least one of: fifth information related to a number of nodes included in a communication path from a base station to the first node; sixth information related to whether the first node is a reference user equipment.

Description

METHOD AND APPARATUS FOR RELAY SELECTION AND RESELECTION IN WIRELESS COMMUNICATION SYSTEM

[0001] The present disclosure relates to a wireless communication system (or a mobile communication system). More specifically, the present disclosure relates to method and apparatus for selection and reselection of relay in a wireless communication system (or a mobile communication system).

[0002] Considering the development of wireless communication from generation to generation, the technologies have been developed mainly for services targeting humans, such as voice calls, multimedia services, and data services. Following the commercialization of 5G (5th generation) communication systems, it is expected that the number of connected devices will exponentially grow. Increasingly, these will be connected to communication networks. Examples of connected things may include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machines, and factory equipment. Mobile devices are expected to evolve in various form-factors, such as augmented reality glasses, virtual reality headsets, and hologram devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (6th generation) era, there have been ongoing efforts to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as beyond-5G systems.

[0003] 6G communication systems, which are expected to be commercialized around 2030, will have a peak data rate of tera (1,000 giga)-level bit per second (bps) and a radio latency less than 100μsec, and thus will be 50 times as fast as 5G communication systems and have the 1 / 10 radio latency thereof.

[0004] In order to accomplish such a high data rate and an ultra-low latency, it has been considered to implement 6G communication systems in a terahertz (THz) band (for example, 95 gigahertz (GHz) to 3THz bands). It is expected that, due to severer path loss and atmospheric absorption in the terahertz bands than those in mmWave bands introduced in 5G, technologies capable of securing the signal transmission distance (that is, coverage) will become more crucial. It is necessary to develop, as major technologies for securing the coverage, Radio Frequency (RF) elements, antennas, novel waveforms having a better coverage than Orthogonal Frequency Division Multiplexing (OFDM), beamforming and massive Multiple-input Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, and multiantenna transmission technologies such as large-scale antennas. In addition, there has been ongoing discussion on new technologies for improving the coverage of terahertz-band signals, such as metamaterial-based lenses and antennas, Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS).

[0005] Moreover, in order to improve the spectral efficiency and the overall network performances, the following technologies have been developed for 6G communication systems: a full-duplex technology for enabling an uplink transmission and a downlink transmission to simultaneously use the same frequency resource at the same time; a network technology for utilizing satellites, High-Altitude Platform Stations (HAPS), and the like in an integrated manner; an improved network structure for supporting mobile base stations and the like and enabling network operation optimization and automation and the like; a dynamic spectrum sharing technology via collision avoidance based on a prediction of spectrum usage; an use of Artificial Intelligence (AI) in wireless communication for improvement of overall network operation by utilizing AI from a designing phase for developing 6G and internalizing end-to-end AI support functions; and a next-generation distributed computing technology for overcoming the limit of UE computing ability through reachable super-high-performance communication and computing resources (such as Mobile Edge Computing (MEC), clouds, and the like) over the network. In addition, through designing new protocols to be used in 6G communication systems, developing mechanisms for implementing a hardware-based security environment and safe use of data, and developing technologies for maintaining privacy, attempts to strengthen the connectivity between devices, optimize the network, promote softwarization of network entities, and increase the openness of wireless communications are continuing.

[0006] It is expected that research and development of 6G communication systems in hyper-connectivity, including person to machine (P2M) as well as machine to machine (M2M), will allow the next hyper-connected experience. Particularly, it is expected that services such as truly immersive eXtended Reality (XR), high-fidelity mobile hologram, and digital replica could be provided through 6G communication systems. In addition, services such as remote surgery for security and reliability enhancement, industrial automation, and emergency response will be provided through the 6G communication system such that the technologies could be applied in various fields such as industry, medical care, automobiles, and home appliances.

[0007] There are needs to develop relay selection / reselection procedure for efficient communication between devices.

[0008] According to an embodiment of the disclosure, a method performed by a first user equipment (UE) is provided. The method comprises: identifying that a selection of a sidelink relay UE is triggered; selecting a second UE for the sidelink relay UE; and transmitting, to the second UE, a message associated with the selection of the second UE.

[0009] According to an embodiment of the disclosure, a first user equipment (UE) is provided. The first UE comprises: a transceiver; and a controller coupled with the transceiver and configured to: identify that a selection of a sidelink relay UE is triggered, select a second UE for the sidelink relay UE, and transmit, to the second UE, a message associated with the selection of the second UE.

[0010] According to an aspect of the present disclosure, there is provided a method performed by a first node in a communication system, the method comprising: determining cell related information of the first node, and transmitting, to a second node, the cell-related information and first information, wherein the first information includes at least one of: fifth information related to a number of nodes included in a communication path from a base station to the first node; sixth information related to whether the first node is a reference user equipment.

[0011] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the fifth information includes at least one of: a number of relay user equipment other than the base station and the first node in the communication path from the base station to the first node; the number of the relay user equipment other than the base station and the first node in the communication path from the base station to the first node plus one; the number of the relay user equipment other than the base station and the first node in the communication path from the base station to the first node plus two; a number of relay user equipment other than the base station in the communication path from the base station to the first node; a number of all nodes in the communication path from the base station to the first node.

[0012] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the first information further includes at least one of: user equipment identifier; seventh information related to mobility of the first node; eighth information related to a load of the first node.

[0013] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the user equipment identifier includes at least one of: a layer 2 identifier of the user equipment; a source layer 2 identifier of the user equipment; a destination layer 2 identifier of the user equipment; an application layer identifier of the user equipment; an identifier for selection and / or reselection of the user equipment.

[0014] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the seventh information includes at least one of: a moving speed of the first node; information related to whether the moving speed of the first node meets or does not meet a first threshold condition; information related to whether the first node is at least one of high-speed motion, low-speed motion or medium-speed motion.

[0015] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the eighth information includes at least one of: a percentage of a load; a percentage of available resources; information related to whether the load of the first node meets or does not meet a second threshold condition; information related to whether the load of the first node is at least one of a high load, a low load or a medium load.

[0016] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the reference user equipment includes at least one of: user equipment with a fixed position or a fixed relative position; user equipment whose location coordinates are determined and can be obtained by other nodes; user equipment moving at a low speed or a relatively low speed; user equipment with a fixed trajectory or a trackable or predictable trajectory; user equipment dedicated to a relay network; user equipment which can be deployed in advance for providing a relay function.

[0017] According to another aspect of the present disclosure, there is provided a method performed by a second node in a communication system, receiving cell-related information and first information from a first node, and based on the first information, determining a previous hop node of the second node on a communication path from a base station to the second node; wherein the first information includes at least one of: fifth information related to a number of nodes included in a communication path from the base station to the first node; sixth information related to whether the first node is a reference user equipment.

[0018] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the fifth information includes at least one of: a number of relay user equipment other than the base station and the first node in the communication path from the base station to the first node; the number of the relay user equipment other than the base station and the first node in the communication path from the base station to the first node plus one; the number of the relay user equipment other than the base station and the first node in the communication path from the base station to the first node plus two; a number of relay user equipment other than the base station in the communication path from the base station to the first node; a number of all nodes in the communication path from the base station to the first node.

[0019] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the first information further includes at least one of: user equipment identifier; seventh information related to mobility of the first node; eighth information related to a load of the first node.

[0020] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the user equipment identifier includes at least one of: a layer 2 identifier of the user equipment; a source layer 2 identifier of the user equipment; a destination layer 2 identifier of the user equipment; an application layer identifier of the user equipment; an identifier for selection and / or reselection of the user equipment.

[0021] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the seventh information includes at least one of: a moving speed of the first node; information related to whether the moving speed of the first node meets or does not meet a first threshold condition; information related to whether the first node is at least one of high-speed motion, low-speed motion or medium-speed motion.

[0022] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the eighth information includes at least one of: a percentage of a load; a percentage of available resources; information related to whether the load of the first node meets or does not meet a second threshold condition; information related to whether the load of the first node is at least one of a high load, a low load or a medium load.

[0023] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the receiving the first information from the first node comprises receiving multiple first information from multiple first nodes, the method further comprises: selecting one of the first nodes as the previous hop node based on at least one of the multiple first information and / or first channel quality related information, wherein the first channel quality related information is obtained by the second node based on a measurement of signals transmitted by the first node.

[0024] According to the method performed by the second node in the communication system provided by the present disclosure, wherein a first node among the multiple first nodes is the reference user equipment which is determined based on sixth information included in the first information received from the first node, and the first node is selected as the previous hop node.

[0025] According to the method performed by the second node in the communication system provided by the present disclosure, the method further comprises updating the fifth information.

[0026] According to another aspect of the present disclosure, there is provided a method performed by a first node in a communication system, the method comprising: transmitting second information to a second node, and receiving fourth information from the second node, wherein the second information includes at least one of: ninth information related to a number of nodes included in a communication path from a first remote user equipment to the first node; relay user equipment related identifier information, including a list of identifiers of relay user equipment included in the communication path from the first remote user equipment to the first node; wherein the fourth information includes at least one of: tenth information related to a number of nodes included in a communication path from a second remote user equipment to the second node; eleventh information related to the reference user equipment.

[0027] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the ninth information includes at least one of: a number of relay user equipment other than the first remote user equipment and the first node in the communication path from the first remote user equipment to the first node; the number of the relay user equipment other than the first remote user equipment and the first node in the communication path from the first remote user equipment to the first node plus one; the number of the relay user equipment other than the first remote user equipment and the first node in the communication path from the first remote user equipment to the first node plus two; a number of relay user equipment other than the first remote user equipment in the communication path from the first remote user equipment to the first node; a number of all nodes in the communication path from the first remote user equipment to the first node.

[0028] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the tenth information includes at least one of: a number of relay user equipment other than the second remote user equipment and the second node in the communication path from the second remote user equipment to the second node; the number of the relay user equipment other than the second remote user equipment and the second node in the communication path from the second remote user equipment to the second node plus one; the number of the relay user equipment other than the second remote user equipment and the second node in the communication path from the second remote user equipment to the second node plus two; a number of relay user equipment other than the second remote user equipment in the communication path from the second remote user equipment to the second node; a number of all nodes in the communication path from the second remote user equipment to the second node.

[0029] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the eleventh information includes at least one of: a number of the reference user equipment; twelfth information related to whether the second node is a reference user equipment.

[0030] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the second information further includes at least one of a first remote user equipment identifier and a second remote user equipment identifier.

[0031] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the fourth information further includes at least one of: at least one of a second remote user equipment identifier and a first remote user equipment identifier; thirteenth information related to mobility of the second node; fourteenth information related to a load of the second node.

[0032] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the first remote user equipment identifier, the second remote user equipment identifier, or the relay user equipment identifier includes at least one of: a layer 2 identifier of the remote user equipment or the relay user equipment; a source layer 2 identifier of the remote user equipment or the relay user equipment; a destination layer 2 identifier of the remote user equipment or the relay user equipment; an application layer identifier of the remote user equipment or the relay user equipment; an identifier for selection and / or reselection of the remote user equipment or the relay user equipment.

[0033] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the thirteenth information includes at least one of: a moving speed of the second node; information related to whether the moving speed of the second node meets or does not meet a third threshold condition; information related to whether the second node is at least one of high-speed motion, low-speed motion or medium-speed motion.

[0034] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the fourteenth information includes at least one of: a percentage of a load; a percentage of available resources; information related to whether the load of the second node meets or does not meet a fourth threshold condition; information related to whether the load of the second node is at least one of a high load, a low load or a medium load.

[0035] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the method further comprises: determining a next hop node of the first node on a communication path from the first node to the second remote user equipment, based on the fourth information.

[0036] According to the method performed by the first node in the communication system provided by the present disclosure, wherein the receiving the fourth information from the second node comprises receiving multiple fourth information from multiple second nodes, the method further comprises: selecting one of multiple second nodes as the next hop node based on at least one of multiple fourth information or second channel quality related information, wherein the second channel quality related information is obtained by the first node based on a measurement of signals transmitted by the second node.

[0037] According to the method performed by the first node in the communication system provided by the present disclosure, wherein a second node among multiple second nodes is the reference user equipment which is determined based on the eleventh information included in the fourth information received from the second node, and the second node is selected as the next hop node; or based on the number of the reference user equipment included in the fourth information received from a second node among multiple second nodes being largest, the second node is selected as the next hop node.

[0038] According to the method performed by the first node in the communication system provided by the present disclosure, the method further comprises updating the tenth information.

[0039] According to the method performed by the first node in the communication system provided by the present disclosure, the method further comprises updating the number of the reference user equipment and transmitting the updated number of the reference user equipment to the previous hop node of the first node or the first remote user equipment.

[0040] According to another aspect of the present disclosure, there is provided a method performed by a second node in a communication system, the method comprising: receiving second information from a first node, and transmitting fourth information to the first node, wherein the second information includes at least one of: ninth information related to a number of nodes included in a communication path from a first remote user equipment to the first node; relay user equipment related identifier information, including a list of identifiers of relay user equipment included in the communication path from the first remote user equipment to the first node; wherein the fourth information includes at least one of: tenth information related to a number of nodes included in a communication path from a second remote user equipment to the second node; eleventh information related to the reference user equipment.

[0041] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the ninth information includes at least one of: a number of relay user equipment other than the first remote user equipment and the first node in the communication path from the first remote user equipment to the first node; the number of the relay user equipment other than the first remote user equipment and the first node in the communication path from the first remote user equipment to the first node plus one; the number of the relay user equipment other than the first remote user equipment and the first node in the communication path from the first remote user equipment to the first node plus two; a number of relay user equipment other than the first remote user equipment in the communication path from the first remote user equipment to the first node; a number of all nodes in the communication path from the first remote user equipment to the first node.

[0042] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the tenth information includes at least one of: a number of relay user equipment other than the second remote user equipment and the second node in the communication path from the second remote user equipment to the second node; the number of the relay user equipment other than the second remote user equipment and the second node in the communication path from the second remote user equipment to the second node plus one; the number of the relay user equipment other than the second remote user equipment and the second node in the communication path from the second remote user equipment to the second node plus two; a number of relay user equipment other than the second remote user equipment in the communication path from the second remote user equipment to the second node; a number of all nodes in the communication path from the second remote user equipment to the second node.

[0043] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the eleventh information includes at least one of: a number of the reference user equipment; twelfth information related to whether the second node is a reference user equipment.

[0044] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the second information further includes at least one of a first remote user equipment identifier and a second remote user equipment identifier.

[0045] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the first remote user equipment identifier, the second remote user equipment identifier, or the relay user equipment identifier includes at least one of: a layer 2 identifier of the remote user equipment or the relay user equipment; a source layer 2 identifier of the remote user equipment or the relay user equipment; a destination layer 2 identifier of the remote user equipment or the relay user equipment; an application layer identifier of the remote user equipment or the relay user equipment; an identifier for selection and / or reselection of the remote user equipment or the relay user equipment.

[0046] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the fourth information further includes at least one of: at least one of a second remote user equipment identifier and a first remote user equipment identifier; thirteenth information related to mobility of the second node; fourteenth information related to a load of the second node.

[0047] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the thirteenth information includes at least one of: a moving speed of the second node; information related to whether the moving speed of the second node meets or does not meet a third threshold condition; information related to whether the second node is at least one of high-speed motion, low-speed motion or medium-speed motion.

[0048] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the fourteenth information includes at least one of: a percentage of a load; a percentage of available resources; information related to whether the load of the second node meets or does not meet a fourth threshold condition; information related to whether the load of the second node is at least one of a high load, a low load or a medium load.

[0049] According to the method performed by the second node in the communication system provided by the present disclosure, the method further comprises updating the ninth information.

[0050] According to the method performed by the second node in the communication system provided by the present disclosure, the method further comprises updating the relay user equipment related identifier information.

[0051] According to the method performed by the second node in the communication system provided by the present disclosure, the method further comprises transmitting third information to a relay user equipment not included in the list or a second remote user equipment, wherein the third information comprises at least one of: the first remote user equipment identifier; the updated ninth information; the updated relay user equipment related identifier information.

[0052] According to the method performed by the second node in the communication system provided by the present disclosure, wherein the receiving the second information from the first node comprises receiving multiple second information from multiple first nodes, the method further comprises: the second node only operating or processing first received second information; or the second node transmitting third information only once.

[0053] According to another aspect of the present disclosure, there is provided a first node including a transceiver configured to transmit and receive signals with the outside; and a controller configured to control the transceiver to perform the method performed by the first node.

[0054] According to another aspect of the present disclosure, there is provided a second node including a transceiver configured to transmit and receive signals with the outside; and a controller configured to control the transceiver to perform the method performed by the second node.

[0055] According to another aspect of the present disclosure, there is provided a non-transitory computer-readable recording medium having stored thereon a program which, when being executed by a computer, performs any of the above methods.

[0056] According to various embodiments of the disclosure, procedures of selection / reselection of relay can be efficiently enhanced in wireless communication system (or mobile communication system).

[0057] Fig. 1 illustrates an exemplary system architecture of System Architecture Evolution (SAE).

[0058] Fig. 2 illustrates an exemplary system architecture according to various embodiments of the present disclosure.

[0059] Fig. 3 illustrates an exemplary architecture of a base station according to various embodiments of the present disclosure.

[0060] Fig. 4A illustrates an exemplary scene in which there are at least two relay user equipment between a base station and a remote user equipment according to various embodiments of the present disclosure.

[0061] Fig. 4B illustrates an exemplary scene in which there are at least two relay user equipment between two remote user equipment according to various embodiments of the present disclosure.

[0062] Fig. 5A illustrates a schematic diagram of a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure.

[0063] Fig. 5B illustrates a schematic diagram of another method a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure.

[0064] Fig. 5C illustrates a schematic diagram of yet another method a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure.

[0065] Fig. 5D illustrates a schematic diagram of yet another method a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure.

[0066] Fig. 5E illustrates a schematic diagram of yet another method a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure.

[0067] Fig. 6 is a block diagram of a node device according to an embodiment of the present disclosure.

[0068] In order to make the objectives, technical solutions and advantages of the embodiments of the present disclosure, a clearly and complete description will be made with respect to the technical solutions of the embodiments of the present disclosure, in conjunction with the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are a part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary skilled in the art without creative labor belong to the protection scope of the present disclosure.

[0069] Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term "couple" and its derivatives refer to any direct or indirect communication between two or more elements, whether those elements are in physical contact with one another. The terms "transmit," "receive," and "communicate," as well as derivatives thereof, encompass both direct and indirect communication. The terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation. The term "or" is inclusive, meaning and / or. The phrase "associated with," as well as derivatives thereof, means to include, be included within, interconnect to or with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The term "controller" means any device, system or part thereof that controls at least one operation. Such a controller may be implemented in hardware or a combination of hardware and software and / or firmware. The function associated with any particular controller may be centralized or distributed, whether locally or remotely. The phrase "at least one of," when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, "at least one of: A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C. For example, "at least one of A, B, or C " includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0070] In addition, various functions described below can be implemented or supported by one or more computer programs, each of which is formed by computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, procedures, functions, objects, classes, instances, related data or parts thereof appropriate for implementation in suitable computer-readable program code. The phrase "computer readable program code" includes any type of computer code, including source code, objective code and executable code. The phrase "computer readable medium" includes any type of medium that can be accessed by a computer, such as Read-Only Memory (ROM), Random Access Memory (RAM), hard disk drive, compact disk (CD), digital video disk (DVD) or any other type of memory. A "non-transitory" computer-readable medium excludes wired, wireless, optical or other communication links that transfer transitory electrical or other signals. A non-transitory computer-readable medium includes a medium in which data can be stored permanently and a medium in which data can be stored and rewritten later, such as rewritable optical disks or erasable memory devices.

[0071] The terms used herein to describe the embodiments of the present application is not intended to limit and / or define the scope of the present application. For example, unless otherwise defined, the technical or scientific terms used in the present disclosure should have ordinary meanings as understood by ordinary skilled in the art to which the present application belongs.

[0072] It should be understood that "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Unless clearly indicated otherwise in the context, similar words such as "a", "an", "the" and the like in the singular form do not indicate a quantitative limitation, but indicate the existence of at least one.

[0073] As used herein, any reference to "one example" or "an example", "one embodiment" or "an embodiment" means that a particular element, feature, structure or characteristic described in conjunction with the embodiment is included in at least one embodiment. The appearances of the phrases "in one embodiment" or "in one example" in different places in the specification are not necessarily all referring to the same embodiment.

[0074] As used herein, "a part of" a certain thing means "at least some of" this thing, so it may mean being less than the entirety thereof or being the entirety thereof. Therefore, "a part of" the thing includes the whole thing as a special case, that is, an example in which the whole thing is a part of the thing.

[0075] It will be further understood that words such as "include", "contain" or the like means that the elements or objects appearing preceding the word encompass the elements or objects listed behind the word as well as their equivalents, without excluding other elements or objects. Words such as "connect", "interconnect" or the like are not limited to physical or mechanical connections, but may include electrical connection, whether direct or indirect. "Up", "Down", "Left" and "Right" are only used to indicate relative positional relationships. When the absolute position of the described object changes, accordingly, the relative positional relationship may change as well.

[0076] The various embodiments discussed below for describing the principle of the present disclosure in this patent document are for illustration only, and should not be construed as limiting the scope of the present disclosure in any way. Those skilled in the art will understand that the principle of the present disclosure may be implemented in any suitably arranged wireless communication system. For example, although the following detailed description of the embodiments of the present disclosure will focus on LTE and 5G communication systems, those skilled in the art can understand that the main points of the present disclosure can also be applied to other communication systems with similar technical backgrounds and channel formats, with slight modifications and basically without departing from the scope of the present disclosure. The schemes of the embodiments of the present application may be applied to various communication systems. For example, the communication systems may include a Global System for Mobile communications (GSM) system, a Code Division Multiple Access (CDMA) system, a Wideband Code Division Multiple Access (WCDMA) system, General Packet Radio Service (GPRS), Long Term Evolution (LTE) system, LTE Frequency Division Duplex (FDD) system, LTE Time Division Duplex (TDD), Universal Mobile Telecommunication System (UMTS), worldwide interoperability for microwave access (WiMAX) communication system, fifth generation (5th generation, 5G) system or New Radio (NR), etc. In addition, the schemes of the embodiments of the present application may be applied to future-oriented communication technologies. In addition, the schemes of the embodiments of the present application may be applied to future-oriented communication technologies.

[0077] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. The description includes various specific details to assist in that understanding but should be regarded as exemplary only. Accordingly, the ordinary skilled in the art will recognize that various changes and modifications to the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and structures may be omitted for clarity and conciseness.

[0078] The terms and wordings used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only, but not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0079] It should be understood that the singular forms "a," "an," and "the" include plural referents, unless clearly indicated otherwise in the context. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0080] The term "include" or "may include" refers to the existence of a corresponding disclosed function, operation or component which can be used in various embodiments of the present disclosure, and does not limit the existence of one or more additional functions, operations, or components. The terms "include" and / or "have" may be construed to represent certain characteristics, numbers, steps, operations, constituent elements, components or combinations thereof, but may not be construed to exclude the possibility of existence of one or more other characteristics, numbers, steps, operations, constituent elements, components or combinations thereof.

[0081] The term "or" used in various embodiments of the present disclosure includes any of the listed terms or all combinations thereof. For example, "A or B" may include A, may include B, or may include both A and B.

[0082] Unless defined differently, all terms used in the present disclosure, including technical or scientific terms, have the same meanings as those understood by the skilled in the art as described in the present disclosure. Common terms as defined in a dictionary are to be interpreted to have meanings consistent with the context in the relevant technical field o, and are not to be interpreted ideally or excessively, unless clearly defined as such in the present disclosure.

[0083] In order to meet an increasing demand for wireless data communication services since a deployment of 4G communication system, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called "beyond 4G network" or "post LTE system".

[0084] Wireless communication is one of the most successful innovations in modern history. Recently, a number of subscribers of wireless communication services has exceeded 5 billion, and it continues growing rapidly. With the increasing popularity of smart phones and other mobile data devices (such as tablet computers, notebook computers, netbooks, e-book readers and machine-type devices) in consumers and enterprises, a demand for wireless data services is growing rapidly. In order to meet rapid growth of mobile data services and support new applications and deployments, it is very important to improve efficiency and coverage of wireless interfaces.

[0085] Figs. 1 to 6 discussed below and various embodiments for describing the principle of the present disclosure in this patent document are only for illustration, and should not be interpreted as limiting the scope of the present disclosure in any way. Those skilled in the art will understand that the principle of the present disclosure may be implemented in any suitably arranged system or device.

[0086] Fig. 1 is an exemplary system architecture 100 of system architecture evolution (SAE). User equipment (UE) 101 is a terminal device for receiving data. An evolved universal terrestrial radio access network (E-UTRAN) 102 is a radio access network, which includes a macro base station (eNodeB / NodeB) that provides UE with interfaces to access the radio network. A mobility management entity (MME) 103 is responsible for managing mobility context, session context and security information of the UE. A serving gateway (SGW) 104 mainly provides functions of user plane, and the MME 103 and the SGW 104 may be in the same physical entity. A packet data network gateway (PGW) 105 is responsible for functions of charging, lawful interception, etc., and may be in the same physical entity as the SGW 104. A policy and charging rules function entity (PCRF) 106 provides quality of service (QoS) policies and charging criteria. A general packet radio service support node (SGSN) 108 is a network node device that provides routing for data transmission in a universal mobile telecommunications system (UMTS). A home subscriber server (HSS)109 is a home subsystem of the UE, and is responsible for protecting user information including a current location of the user equipment, an address of a serving node, user security information, and packet data context of the user equipment, etc.

[0087] Fig. 2 is an exemplary system architecture 200 according to various embodiments of the present disclosure. Other embodiments of the system architecture 200 can be used without departing from the scope of the present disclosure.

[0088] User equipment (UE) 201 is a terminal device for receiving data. A next generation radio access network (NG-RAN) 202 is a radio access network, which includes a base station (a gNB or an eNB connected to 5G core network 5GC, and the eNB connected to the 5GC is also called ng-gNB) that provides UE with interfaces to access the radio network. An access and mobility management function (AMF) entity 203 is responsible for managing mobility context and security information of the UE. A user plane function (UPF) entity 204 mainly provides functions of user plane. A session management function entity SMF 205 is responsible for session management. A data network (DN) 206 includes, for example, services of operators, access of Internet and service of third parties.

[0089] In NR system, in order to support network function virtualization, more efficient resource management and scheduling, a base station (gNB / ng-eNB) that provides a radio network interface for user equipment (UE) can be further divided into a centralized unit gNB-CU / ng-eNB-CU (gNB central unit / ng-eNB central unit) and a distributed unit gNB-DU / ng-eNB-DU (gNB distributed unit / ng-eNB distributed unit) (abbreviated as CU and DU in the present invention), as shown in Fig. 3(a). gNB-CU has radio resource control (RRC), service data adaptation protocol (SDAP) and packet data convergence protocol (PDCP) protocols, etc, while ng-eNB-CU has RRC and PDCP layers. gNB-DU / ng-eNB-DU has radio link control (RLC) protocol, medium access control (MAC) and physical layer, etc. There is a standardized public interface F1 between gNB-CU and gNB-DU, and a standardized public interface W1 between ng-eNB-CU and ng-eNB-DU. The F1 interface is divided into control plane F1-C and user plane F1-U. The transport network layer of F1-C is based on IP transport. In order to transmit signaling more reliably, SCTP (stream control transmission protocol) protocol is added to IP. The protocol of the application layer is F1AP (F1 Application Protocol, F1 Application Protocol / F1 Interface Application Protocol). SCTP can provide reliable application layer message transmission. The transport layer of F1-U (F1-User, user plane of F1) is UDP / IP, and GTP-U (GPRS tunneling protocol for the user plane) is used to carry user plane protocol data unit PDU above UDP / IP. Further, for gNB-CU, as shown in Fig. 3(b), gNB-CU can include gNB-CU-CP (the control plane part of the centralized unit of the base station) and gNB-CU-UP (the user plane part of the centralized unit of the base station). gNB-CU-CP includes the function of the control plane of the base station and has RRC and SDAP protocol layers, and gNB-CU-UP includes the function of the user plane of the base station and has SDAP and PDCP protocol layers. gNB-CU-CP and gNB-CU-UP are standardized public interfaces E1, and the protocol is E1AP. The interface between the control plane part of the centralized unit of the base station and the distributed unit of the base station is F1-C interface, that is, the control plane interface of F1, and the interface between the user plane part of the centralized unit of the base station and the distributed unit of the base station is F1-U interface, that is, the user plane interface of F1. In addition, in the NR system, the base station providing the E-UTRA user plane and control plane which accesses the 5G core network is called ng-eNB. In order to support virtualization, such a base station (ng-eNB) can also be further divided into a centralized unit ng-eNB-CU (gNB central unit / ng-eNB central unit) and a distributed unit ng-eNB-DU (gNB distributed unit / ng-eNB distributed unit) (abbreviated as CU and DU in the present invention), as shown in Fig. 3(c). ng-eNB-CU has RRC and PDCP layers. gNB-DU / ng-eNB-DU has radio link control protocol (RLC), medium access control (MAC) and physical layer, etc. There is a standardized public interface W1 between ng-eNB-CU and ng-eNB-DU. W1 interface is divided into control plane W1-C and user plane W1-U. The transport network layer of W1-C is based on IP transport. In order to transmit signaling more reliably, SCTP protocol is added to IP. The protocol of the application layer is W1AP. The transport layer of W1-U is UDP / IP, and GTP-U is used to carry user plane protocol data unit PDU above UDP / IP.

[0090] Exemplary embodiments of the present disclosure are further described below with reference to the accompanying drawings.

[0091] The text and drawings are provided as examples only to help understand the present disclosure. They should not be construed as limiting the scope of the present disclosure in any way. Although certain embodiments and examples have been provided, based on the disclosure herein, it is obvious to those skilled in the art that changes can be made to the illustrated embodiments and examples without departing from the scope of this disclosure.

[0092] Before introducing the specific content, some assumptions and some definitions of the present invention are given below.

[0093] * The message names in the present invention are only examples, and other message names can be used.

[0094] * The "first" and "second" included in the message name of the present invention are only examples of messages and do not represent the execution order.

[0095] * Detailed description of steps irrelevant to the present invention is omitted in the present invention.

[0096] * In the present invention, the steps in each procedure can be executed in combination with each other or independently. The execution steps of each process are only examples, and other possible execution orders are not excluded.

[0097] * In the present invention, the base station may be a 5G base station (such as gNB, ng-eNB), a 4G base station (such as eNB), a 6G base station or other types of access nodes.

[0098] * In the present invention, data transmission refers to the reception or transmission of data.

[0099] The nodes involved in the invention are:

[0100] * A first relay user equipment (Relay UE).

[0101] * A second relay user equipment.

[0102] * A first remote user equipment (Remote UE).

[0103] * A second remote user equipment.

[0104] * The base station, or the centralized unit of the base station, or the control plane part of the centralized unit of the base station.

[0105] At present, in sidelink relay, the selection and / or reselection of user equipment mainly focuses on the scenario where only a single relay user equipment is in the communication link, and the scenario where multiple relay user equipment are in the communication link has not been studied. That is, at present, the side link relay only studies the selection and / or reselection of relay user equipment in the scenario where there is only one relay user equipment in the communication link, but does not study the selection and / or reselection of relay user equipment in the scenario where there are at least two relay user equipment in the communication link. If there is only a single relay user equipment in the communication link, it is impossible to ensure the remote user equipment in the deep coverage blind area or the remote user equipment with a long communication distance to communicate.

[0106] Of course, it can be understood that the above technical problems are only taken as an example of the present disclosure and are not limited, and any technical problems that can be solved according to the technical solution of the present disclosure belong to the scope to be protected by the present invention.

[0107] Various embodiments of the present invention provide a method for selecting and / or reselecting relay user equipment, which can support the existence of at least two relay user equipment in a communication link (the corresponding network can be called a multi-hop relay network), thus ensuring the communication between remote user equipment.

[0108] As an embodiment, various embodiments of the present disclosure provide a method performed by a first node in a communication system, the method comprising: determining cell related information of the first node, and transmitting, to a second node, the cell-related information and first information, wherein the first information includes at least one of: fifth information related to a number of nodes included in a communication path from a base station to the first node; sixth information related to whether the first node is a reference user equipment.

[0109] As yet another embodiment, various embodiments of the present disclosure provide a method performed by a second node in a communication system, receiving cell-related information and first information from a first node, and based on the first information, determining a previous hop node of the second node on a communication path from a base station to the second node; wherein the first information includes at least one of: fifth information related to a number of nodes included in a communication path from the base station to the first node; sixth information related to whether the first node is a reference user equipment.

[0110] The method for selecting and / or reselecting relay user equipment provided by various embodiments of the present disclosure ensures that the remote user equipment with the communication requirement can discover counterpart remote user equipment or networks through at least two relay user equipment (for example, in the scenario of Fig. 4A, that is, the first node and the second node are located on the first communication link from the base station to the second remote user equipment, and the first communication link includes multiple relay user equipment); and ensures that the remote user equipment with the communication requirement can select and / or reselect to the appropriate relay user equipment, thereby ensuring the communication of the remote user equipment.

[0111] As another embodiment, various embodiments of the present disclosure provide a method performed by a first node in a communication system, the method comprising: transmitting second information to a second node, and receiving fourth information from the second node, wherein the second information includes at least one of: ninth information related to a number of nodes included in a communication path from a first remote user equipment to the first node; relay user equipment related identifier information, including a list of identifiers of relay user equipment included in the communication path from the first remote user equipment to the first node; wherein the fourth information includes at least one of: tenth information related to a number of nodes included in a communication path from a second remote user equipment to the second node; eleventh information related to the reference user equipment.

[0112] As yet another embodiment, various embodiments of the present disclosure provide a method performed by a second node in a communication system, the method comprising: receiving second information from a first node, and transmitting fourth information to the first node, wherein the second information includes at least one of: ninth information related to a number of nodes included in a communication path from a first remote user equipment to the first node; relay user equipment related identifier information, including a list of identifiers of relay user equipment included in the communication path from the first remote user equipment to the first node; wherein the fourth information includes at least one of: tenth information related to a number of nodes included in a communication path from a second remote user equipment to the second node; eleventh information related to the reference user equipment.

[0113] The method for selecting and / or reselecting relay user equipment provided by various embodiments of the present disclosure ensures that remote user equipment with the communication requirement can discover counterpart remote user equipment or networks through at least two relay user equipment (for example, in the scenario of Fig. 4B, that is, the first node and the second node are located on the second communication link from the first remote user equipment to the second remote user equipment, and the second communication link includes multiple relay user equipment); and ensures that the remote user equipment with the communication requirement can select and / or reselect to the appropriate relay user equipment, thereby ensuring the communication of the remote user equipment.

[0114] Of course, it can be understood that the technical solution of the present invention is not limited to the multi-hop relay network, and the technical solution of the present invention can also be applied to the scene including only one relay user equipment.

[0115] Hereinafter, example scenarios of the communication link including multiple relay user equipment according to various embodiments of the present invention will be described with reference to Figs. 4A to 4B.

[0116] Fig. 4A is a scene in which there are at least two relay user equipment between a base station and a remote user equipment according to various embodiments of the present disclosure.

[0117] Fig. 4B is a scene in which there are at least two relay user equipment between two remote user equipment according to various embodiments of the present disclosure.

[0118] It should be noted that Figs. 4A to 4B only describe some example scenarios, and the scenarios that can be solved for the selection and / or reselection solution to be described below include but are not limited to the example scenarios shown in Figs. 4A to 4B.

[0119] First of all, it should be pointed out that the reasons that trigger the selection and / or reselection of user equipment include at least one of the following reasons:

[0120] - indicated by upper layer ;

[0121] - triggered by PC5 link signal quality;

[0122] - PC5 radio link failure;

[0123] - PC5 connection release.

[0124] For triggering the selection and / or reselection of the user equipment, one possible implementation is that if it is the PC5 link signal quality trigger or the PC5 radio link failure or the PC5 connection release between the remote user equipment and the relay user equipment, the selection and / or reselection of the relay user equipment is triggered by the remote user equipment.

[0125] If it is the PC5 link signal quality trigger or the PC5 radio link failure or the PC5 connection release between relay user equipment, in one embodiment, the selection and / or reselection of the relay user equipment is triggered by one of the relay user equipment negotiated in advance; or in another embodiment, the relay user equipment (for example, either relay user equipment or both) informs the remote user equipment to trigger the selection and / or reselection of the relay user equipment.

[0126] Hereinafter, the method for selecting and / or reselecting relay user equipment provided by various embodiments of the present disclosure will be described in detail with reference to Figs. 5A to 5E.

[0127] Fig. 5A is a schematic diagram of a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure. Referring to Figs. 4A and 5A, as an example, when the first node is the first relay user equipment, the second node may be the second relay user equipment; as another example, when the first node is a second relay user equipment, the second node may be a second remote user equipment, but the present disclosure is not limited thereto.

[0128] As shown in Fig. 5A, the method may include the following steps:

[0129] A first node transmits cell-related information and first information for selection and / or reselection of relay user equipment to a second node (wherein, before transmitting the cell-related information and the first information to the second node, the method may further include determining the cell-related information of the first node), and the first information may include at least one of the following information, for example:

[0130] - a user equipment identifier, that is, the information for identifying the first node;

[0131] - fifth information (also called hop count information) related to a number of nodes included in the communication path from the base station to the first node;

[0132] - seventh information related to the mobility of the first node (also referred to as mobility related information);

[0133] - eighth information (which may also be called load information) related to the load of the first node;

[0134] - sixth information related to whether the first node is a reference user equipment.

[0135] Herein, for example, the user equipment identifier may at least contain one of the following information:

[0136] - a layer 2 identifier of the user equipment;

[0137] - a source Layer 2 identifier of the user equipment;

[0138] - a destination layer 2 identifier of the user equipment;

[0139] - an application layer identifier of the user equipment;

[0140] - an identifier for selection and / or reselection of the user equipment.

[0141] Herein, the cell-related information may include at least one of the following information, for example:

[0142] - a physical cell identifier;

[0143] - a Cell Global identifier;

[0144] - Carrier frequency information.

[0145] Taking Fig. 4A as an example, the definition of the fifth information is based on different embodiments. In one embodiment, the hop count information is defined as a number of relay user equipment other than the base station and the first node in the link from the base station to the first node. In another embodiment, the hop count information is defined as the number of the relay user equipment other than the base station and the first node in the link from the base station to the first node plus one. In another embodiment, the hop count information is defined as the number of the relay user equipment other than the base station and the first node in the link from the base station to the first node plus two. In another embodiment, the hop count information is defined as a number of relay user equipment other than the base station (including the first node) in the link from the base station to the first node. In another embodiment, the hop count information is defined as a number of all nodes (that is, including the base station, the first node and other relay user equipment) in the link from the base station to the first node.

[0146] The seventh information related to the mobility of the first node may include at least one of the following information, for example:

[0147] - a moving speed of the first node.

[0148] - information related to whether the moving speed of the first node meets or does not meet a first threshold condition. When the moving speed of the first node exceeds or falls below the first threshold condition, the information is included in the seventh information. Herein the first threshold condition can be configured by network signaling, or can be determined by the network system information or can be a predetermined value.

[0149] - information related to whether the first node is at least one of high-speed motion, low-speed motion or medium-speed motion. Herein the definitions of high-speed, low-speed or medium-speed are preset according to requirements.

[0150] The eighth information related to the load of the first node may include at least one of the following information, for example:

[0151] - a percentage of a comprehensive load, where 0 means no load and 100 means a full load.

[0152] - a percentage of available resources, where 0 means no available resources.

[0153] - information related to whether the load of the first node meets or does not meet a second threshold condition. When the load of the first node exceeds or falls below the second threshold condition, the information is included in the eighth information. Herein the second threshold condition can be configured by network signaling, or can be determined by the network system information or can be a predetermined value.

[0154] - information related to whether the load of the first node is at least one of a high load, a low load or a medium load. Herein the definitions of high load, low load and medium load are set in advance according to requirements.

[0155] Herein, the reference user equipment is a kind of relay user equipment, and the reference user equipment may have at least one of the following characteristics:

[0156] - a fixed position or a fixed relative position;

[0157] - location coordinates are determined and can be obtained by other nodes;

[0158] - moving at a low speed or a relatively low speed;

[0159] - a fixed trajectory or a trackable or predictable trajectory;

[0160] - dedicated to a relay network;

[0161] - It can be deployed in advance and mainly provides a relay function.

[0162] One possible implementation is that the second node prioritizes to select and / or reselect the reference user equipment as the relay user equipment.

[0163] One possible implementation is that the base station prioritizes to select the reference user equipment as the target relay user equipment for handover or path switch.

[0164] The first information may be included in the PC5 message or the RRC information.

[0165] The first node may send the first information by broadcast, multicast or unicast.

[0166] After the second node receives the first information, the second node determines the cell of the first node according to the cell-related information contained in the first information.

[0167] If the second node receives multiple first messages from multiple first nodes, the second node may select and / or reselects one of the first nodes as the relay user equipment for the previous hop in the communication link with the base station, based on one or more information (such as the hop count information; the mobility related information; the load information; the sixth information, etc.), and / or based on the channel quality related information (such as reference signal received power, etc.) obtained by the measurement of signals transmitted by the first node.

[0168] In one embodiment, the second node may select and / or reselect the first node with reference to the hop count information. For example, the first node with fewer hops can be selected as the relay user equipment for the previous hop.

[0169] In another embodiment, the second node may select and / or reselect the first node with reference to the mobility related information. For example, a static or relatively static first node can be selected as the relay user equipment for the previous hop. For another example, the first node with a low moving speed or a relatively low moving speed can be selected as the relay user equipment for the previous hop.

[0170] In another embodiment, the second node may select and / or reselect the first node with reference to the load information. For example, the first node with a lower load can be selected as the relay user equipment for the previous hop.

[0171] In another embodiment, the second node may select and / or reselect the first node with reference to the sixth information. For example, the first node that is the reference user equipment can be selected as the relay user equipment for the previous hop.

[0172] In another embodiment, the second node may select and / or reselect the first node by comprehensively referring to multiple information included in the first information. For example, if the first nodes selected by referring to different information are different (for example, one first node has fewer hops but is not a reference user equipment, while another first node is a reference user equipment but has more hops), the first node that is a reference device is prioritized to be selected and / or reselected.

[0173] In another embodiment, the second node may select and / or reselect the first node by comprehensively referring to multiple information included in the first information. For example, if the first nodes selected by referring to different information are different (for example, one first node has fewer hops but is not a reference user equipment, while another first node is a reference user equipment but has more hops), the first node with fewer hops is prioritized to be selected and / or reselected.

[0174] In another embodiment, the second node may select and / or reselect the first node by comprehensively referring to one or more pieces of information included in the first information and channel quality related information. For example, if the first nodes selected by referring to different information are different (for example, one first node has fewer hops, while another first node has more hops but better channel quality), the first node with better channel quality is prioritized to be selected and / or reselected.

[0175] When the second node selects the first node, the second node sets the cell-related information as the cell-related information of the selected first node.

[0176] When the second node re-selects the first node, the second node sets or updates the cell-related information as the cell-related information of the re-selected first node.

[0177] When the second node selects and / or reselects the first node, the second node adds one to the hop count and stores it.

[0178] If the first node is the first relay user equipment and the second node is the second relay user equipment, after the second relay user equipment reselects the first relay user equipment, the second relay user equipment can send the updated cell-related information to other relay user equipment or remote user equipment. The second relay user equipment may send the updated cell-related information by broadcasting, multicast or unicast.

[0179] It is also worth mentioning that the first node can update the first information.

[0180] The first node may send the updated first information to the second node in the form of broadcast, multicast or unicast. The second node can reselect the first node according to the latest first information received.

[0181] Through the above method, it is ensured that the second node can select or reselect to the appropriate previous hop node (i.e., the first node) under the scenario that there are multiple relay user equipment in the communication link, and the second node can update and store the camped cell information, thus ensuring that subsequently the second node can quickly connect to the base station to which the cell belongs. At the same time, by the way that the relay user equipment of each hop selects and / or reselects the previous hop only according to the information received from the previous hop, the complexity of the function of selecting and / or reselecting each hop is ensured to be controlled at a reasonable level.

[0182] Fig. 5B is a schematic diagram of another method a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure. Referring to Figs. 4B and 5B, as an example, when the first node is the first relay user equipment, the second node may be the second relay user equipment; as another example, when the first node is a second relay user equipment, the second node may be a second remote user equipment; as yet another example, when the first node is a first remote user equipment, the second node is a first relay user equipment.

[0183] As shown in Fig. 5B, the method may include the following steps:

[0184] A first node transmits second information to a second node for requesting selection and / or reselection of relay user equipment, and the second information may include at least one of the following information, for example:

[0185] - a remote user equipment identifier (e.g. at least one of a first remote user equipment identifier and a second remote user equipment identifier);

[0186] - ninth information (also called hop count information) related to a number of nodes included in a communication path from a first remote user equipment to the first node;

[0187] - relay user equipment related identifier information.

[0188] Herein, the remote user equipment identifier may, for example, at least include one of the following information:

[0189] - a layer 2 identifier of the remote user equipment;

[0190] - a source Layer 2 identifier of the remote user equipment;

[0191] - a destination layer 2 identifier of the remote user equipment;

[0192] - an application layer identifier of the remote user equipment;

[0193] - an identifier for selection and / or reselection of the remote user equipment.

[0194] Herein, the source layer 2 identifier of the remote user equipment may be the identifier of the first remote user equipment, which is used to identify the first remote user equipment that needs to find the second remote user equipment.

[0195] Herein, the destination layer 2 identifier of the remote user equipment can be the identifier of the second remote user equipment, which is used to identify the second remote user equipment that the first remote user equipment needs to find.

[0196] Herein, the identifier for selection and / or reselection of the remote user equipment can be an access layer identifier or an application layer identifier. The identifier for selection and / or reselection of the remote user equipment can be configured to the remote user equipment in advance by the network side.

[0197] Taking Fig. 4B as an example, the definition of the ninth information (also called hop count information) related to a number of nodes included in a communication path from a first remote user equipment to the first node is based on different embodiments. In one embodiment, the hop count information is defined as a number of relay user equipment other than the first remote user equipment and the first node in the link from the first remote user equipment to the first node. In another embodiment, the hop count information is defined as the number of the relay user equipment other than the first remote user equipment and the first node in the link from the first remote user equipment to the first node plus one. In another embodiment, the hop count information is defined as the number of the relay user equipment other than the first remote user equipment and the first node in the link from the first remote user equipment to the first node plus two. In another embodiment, the hop count information is defined as a number of relay user equipment other than the first remote user equipment (including the first node) in the link from the first remote user equipment to the first node. In another embodiment, the hop count information is defined as a number of all nodes (that is, including the first remote user equipment, the first node and other relay user equipment) in the link from the first remote user equipment to the first node.

[0198] Herein, the relay user equipment related identifier information, for example, can at least include a list of relay user equipment identifiers, which is used to record relay user equipment that has passed in the path. Herein, the list of relay user equipment identifiers may contain at least one relay user equipment identifier. Herein, the relay user equipment identifier may include at least one of the following information, for example:

[0199] - a layer 2 identifier of the relay user equipment;

[0200] - a Source Layer 2 identifier of the relay user equipment;

[0201] - a destination layer 2 identifier of the relay user equipment;

[0202] - an application layer identifier of relay user equipment;

[0203] - an identifier for selection and / or reselection of the relay user equipment.

[0204] The second information may be included in a PC5 message, such as a Discovery message used by PC5 for discovery. It can also be included in RRC information.

[0205] The first node may send the second information by broadcast, multicast or unicast.

[0206] After the second node receives the second information, the second node confirms the first remote user equipment (i.e. the source remote user equipment) and the second remote user equipment (i.e. the destination remote user equipment) according to the remote user equipment identifier contained in the received second information, wherein the first remote user equipment and the second remote user equipment form a remote user equipment pair.

[0207] After the second node receives the hop count information contained in the second information, the second node adds one to the hop count information and stores it.

[0208] After the second node receives the list of relay user equipment identifiers contained in the relay user equipment identifier information contained in the second information, the second node stores the list of relay user equipment identifiers. If the second node is a relay user equipment, the second node sequentially adds the relay user equipment identifier of the second node to the list of relay user equipment identifiers.

[0209] If the destination layer 2 identifier of the remote user equipment is the identifier of the second remote user equipment, after receiving the identifier, the second node inquires / finds / looks up whether the path to the second remote user equipment identified by the destination layer 2 identifier is stored; if so, this path is selected as the path from the second node to the second remote user equipment; if it does not exist, the third information is sent to other relay user equipment or the second remote user equipment, and the third information may include at least one of the following information, for example:

[0210] - the received remote user equipment identifier;

[0211] - updated hop count information;

[0212] - updated relay user equipment related identifier information.

[0213] The second node may send the third information by broadcast, multicast or unicast.

[0214] It should be noted that there is a corresponding relationship between that the second node transmits the third information to other relay user equipment or second remote user equipment and that the first node transmits the second information to the second node: the second node that transmits the third information is the first node for the next hop that transmits the second information, and the third information sent is the second information transmitted by the next hop.

[0215] In one embodiment, the second node only transmits the third information to the relay user equipment that is not in the list of relay user equipment identifiers or the second remote user equipment.

[0216] In an embodiment, the second node judges whether the user equipment identifier of the second node already exists in the list of relay user equipment identifiers, and if so, the second node does not send the third information.

[0217] The second node may receive multiple second information from multiple first nodes.

[0218] In one embodiment, the second node only operates or processes the first received second information from the first node: the second node stores the first received second information, and the second node determines the related information of the first node according to the stored second information.

[0219] In one embodiment, the second node does not operate or process other second information received from other first nodes later.

[0220] In an embodiment, after the second node has sent the third information, the second node does not send other or new third information for the same remote user equipment pair.

[0221] Through the above method, it is ensured that the second node receiving the second information does not need to repeatedly operate multiple pieces of second information aiming at the same remote user equipment pair, thus saving the processing overhead of the second node, reducing the transmitting of the third information and alleviating the potential signaling storm problem during the discovery stage in the user equipment. In addition, by the way that the second node only operates or processes the first received second information, the time delay during the discovery stage in the user equipment is reduced.

[0222] Fig. 5C is a schematic diagram of yet another method a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure. Referring to Figs. 4B and 5C, as an example, when the first node is the first relay user equipment, the second node may be the second relay user equipment; as another example, when the first node is a second relay user equipment, the second node is a second remote user equipment; as yet another example, when the first node is a first remote user equipment, the second node is a first relay user equipment.

[0223] As shown in Fig. 5C, in this method, the following steps may be included:

[0224] The second node transmits fourth information to the first node for responding to the selection and / or reselection of the relay user equipment, and the fourth information may include at least one of the following information, for example:

[0225] - a remote user equipment identifier (e.g., at least one of a second remote user equipment identifier and a first remote user equipment identifier);

[0226] - tenth information (also called hop count information) related to a number of nodes included in a communication path from a second remote user equipment to the second node;

[0227] - thirteenth information related to the mobility of the second node;

[0228] - fourteenth information related to the load of the second node;

[0229] - eleventh information related to the reference user equipment.

[0230] Wherein, for example, the remote user equipment identifier may at least contain one of the following information:

[0231] - a layer 2 identifier of the remote user equipment;

[0232] - a source Layer 2 identifier of the remote user equipment;

[0233] - a destination layer 2 identifier of the remote user equipment;

[0234] - an application layer identifier of the remote user equipment;

[0235] - an identifier for selection and / or reselection of the remote user equipment.

[0236] Herein, the source layer 2 identifier of the remote user equipment may be the identifier of the second remote user equipment, which is used to identify the second remote user equipment that needs to respond to the first remote user equipment.

[0237] Herein, the destination layer 2 identifier of the remote user equipment may be the identifier of the first remote user equipment, which is used to identify the first remote user equipment to which the second remote user equipment needs to respond.

[0238] It is worth mentioning that, in one embodiment, when the second node generates the fourth information, the source layer 2 identifier of the remote user equipment in the fourth information may be set as the destination layer 2 identifier of the remote user equipment in the second information received by the second node; and / or the destination layer 2 identifier of the remote user equipment in the fourth information can be set as the source layer 2 identifier of the remote user equipment in the second information received by the second node.

[0239] Herein, the identifier for selection and / or reselection of the remote user equipment can be an access layer identifier or an application layer identifier. The identifier for selection and / or reselection of the remote user equipment can be configured to the remote user equipment in advance by the network side.

[0240] Taking Fig. 4B as an example, the definition of tenth information (also called hop count information) related to a number of nodes included in a communication path from a second remote user equipment to the second node is based on different embodiments. In one embodiment, the hop count information is defined as a number of relay user equipment other than the second remote user equipment and the second node in the link from the second remote user equipment to the second node. In another embodiment, the hop count information is defined as the number of the relay user equipment other than the second remote user equipment and the second node in the link from the second remote user equipment to the second node plus one. In another embodiment, the hop count information is defined as the number of the relay user equipment other than the second remote user equipment and the second node in the link from the second remote user equipment to the second node plus two. In another embodiment, the hop count information is defined as a number of relay user equipment other than the second remote user equipment (including the second node) in the link from the second remote user equipment to the second node. In another embodiment, the hop count information is defined as a number of all nodes (that is, including the second remote user equipment, the second node and other relay user equipment) in the link from the second remote user equipment to the second node.

[0241] The thirteenth information related to the mobility of the second node may include at least one of the following information, for example:

[0242] - a moving speed of the second node.

[0243] - information related to whether the moving speed of the second node meets or does not meet a third threshold condition, When the moving speed of the second node exceeds or falls below the third threshold condition, the information is included in the thirteenth information. Herein the third threshold condition can be configured by network signaling, or can be determined by the network system information or can be a predetermined value.

[0244] - information related to whether the second node is at least one of high-speed motion, low-speed motion or medium-speed motion. Herein the definitions of high-speed, low-speed or medium-speed are preset according to requirements.

[0245] The fourteenth information related to the load of the second node may include at least one of the following information, for example:

[0246] - a percentage of a comprehensive load, where 0 means no load and 100 means a full load.

[0247] - a percentage of available resources, where 0 means no available resources.

[0248] - information related to whether the load of the second node meets or does not meet a fourth threshold condition. When the load of the second node exceeds or falls below the fourth threshold condition, the information is included in the fourteenth information. Herein the fourth threshold condition can be configured by network signaling, or can be determined by the network system information or can be a predetermined value.

[0249] - information related to whether the load of the second node is at least one of a high load, a low load or a medium load. Herein the definitions of high load, low load and medium load are set in advance according to requirements.

[0250] The eleventh information related to the reference user equipment may include at least one of the following information, for example:

[0251] - a number of the reference user equipment;

[0252] - twelfth information related to whether the second node is a reference user equipment.

[0253] It is worth mentioning that the reference user equipment is a kind of relay user equipment, and the reference user equipment may have at least one of the following characteristics:

[0254] - a fixed position or a fixed relative position;

[0255] - location coordinates are determined and can be obtained by other nodes;

[0256] - moving at a low speed or a relatively low speed;

[0257] - a fixed trajectory or a trackable or predictable trajectory;

[0258] - dedicated to a relay network;

[0259] - It can be deployed in advance and mainly provides a relay function.

[0260] One possible implementation is that the first node prioritizes to select and / or reselect the reference user equipment as the relay user equipment.

[0261] Herein, the number of reference user equipment can be the number of reference user equipment included in the path from the second node to the second remote user equipment; If the second node is a reference user equipment, the number may or may not include the second node.

[0262] The fourth information may be included in a PC5 message, such as a Response message for Discovery in the PC5. It can also be included in RRC information.

[0263] The second node may send the fourth information by unicast. The second node determines the first node that needs to send the fourth information according to the list of the relay user equipment identifiers contained in the stored second information.

[0264] If the first node receives multiple fourth messages from multiple second nodes, the first node may select and / or reselects one of the second nodes as the relay user equipment for the next hop in the communication link with the second remote user equipment, based on one or more information (such as the hop count information; the mobility related information; the load information; the eleventh information, etc.), and / or based on the channel quality related information (such as reference signal received power, etc.) obtained by the measurement of signals transmitted by the second nodes.

[0265] In one embodiment, the first node may select and / or reselect the second node with reference to the hop count information. For example, a second node with fewer hops to the second remote user equipment can be selected as the relay user equipment for the next hop.

[0266] In another embodiment, the first node may select and / or reselect the second node with reference to the mobility related information. For example, a static or relatively static second node can be selected as the relay user equipment for the next hop. For another example, the second node with a low moving speed or a relatively low moving speed can be selected as the relay user equipment for the next hop.

[0267] In another embodiment, the first node may select and / or reselect the second node with reference to the load information. For example, the second node with a lower load can be selected as the relay user equipment for the next hop.

[0268] In another embodiment, the first node may select and / or reselect a second node with reference to the eleventh information. For example, the second node that is the reference user equipment can be selected as the relay user equipment for the next hop. For another example, the second node with a lager number of reference user equipment included in the eleventh information can be selected as the relay user equipment for the next hop.

[0269] In another embodiment, the first node may select and / or reselect the second node by comprehensively referring to multiple information included in the fourth information. For example, if the second nodes selected by referring to different information are different (for example, one second node has fewer hops but is not a reference user equipment, while another second node is a reference user equipment but has more hops), the second node that is a reference device is prioritized to be selected and / or reselected. For another example, if the second nodes selected by referring to different information are different (for example, one second node has better channel quality, but the number of reference user equipment on the path from the second remote user equipment to the second node is less, while another second node with a larger number of reference user equipment on the path), the second node with a larger number of reference user equipment on the path is prioritized to be selected and / or reselected.

[0270] In another embodiment, the first node may select and / or reselect the second node by comprehensively referring to multiple information included in the fourth information. For example, if the second nodes selected by referring to different information are different (for example, one second node has fewer hops but is not a reference user equipment, while another second node is a reference user equipment but has more hops), the second node with fewer hops is prioritized to be selected and / or reselected.

[0271] In another embodiment, the first node may select and / or reselect the second node by comprehensively referring to one or more pieces of information included in the fourth information and channel quality related information. For example, if the second nodes selected by referring to different information are different (for example, one second node has fewer hops and another second node has more hops but better channel quality), the second node with better channel quality is prioritized to be selected and / or reselected.

[0272] When the first node selects and / or reselects the second node, the first node adds one to the hop count and stores it.

[0273] When the first node selects and / or reselects a second node, for the number of reference user equipment contained in the fourth information received by the first node from the selected and / or reselected second node, if the second node is the reference user equipment, the first node can perform different operations based on different situations: in one embodiment, if the number of reference user equipment does not include the second node, the first node adds one to the number of the reference user equipment and sends the updated number of the reference user equipment to the relay user equipment for the previous hop or the first remote user equipment; in another embodiment, if the second node is included in the number of reference user equipment, the first node judges whether it is a reference user equipment, and if so, the first node adds one to the number of the reference user equipment and sends the updated number of the reference user equipment to the relay user equipment for the previous hop or the first remote user equipment.

[0274] It should be noted that there is a corresponding relationship between that the first node transmits the response information to the relay user equipment for the previous hop or the first remote user equipment and that the second node transmits the fourth information to the first node: the first node that transmits the response information is the second node for the next hop that transmits the fourth information, and the response information sent is the fourth information transmitted by the previous hop.

[0275] It is also worth mentioning that the second node can update the fourth information.

[0276] The second node may send the updated fourth information to the first node by unicast. The first node can reselect the second node according to the latest fourth information received.

[0277] Through the above method, it is ensured that the first node can select or reselect to the appropriate second node under the scenario that there are multiple relay user equipment in the communication link, and the path between the first remote user equipment and the second remote user equipment is ensured to be smooth by selecting and / or reselecting the next hop by each hop relay user equipment, thus ensuring that subsequently the first remote user equipment can be quickly connected to the second remote user equipment.

[0278] Fig. 5D is a schematic diagram of yet another method a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure. As shown in Fig. 5D, in this method, one or more of the following steps 0 to 7 may be included.

[0279] Step 0, the first relay user equipment camps on or is connected to the first cell.

[0280] Step 1: a first relay user equipment transmits a PC5 and / or RRC message to a second relay user equipment, wherein the PC5 and / or RRC message contains first information of the first relay user equipment.

[0281] Step 2, after receiving the first information from the first relay user equipment, the second relay user equipment selects and / or reselects to the first relay user equipment.

[0282] Step 3, the second relay user equipment stores the cell of the first relay user equipment, that is, the first cell, as the camped cell.

[0283] Step 4, the second relay user equipment adds one to the hop count contained in the received first information of the first relay user equipment and includes it in the first information of the second relay user equipment.

[0284] Step 5, the second relay user equipment transmits a PC5 and / or RRC message to the second remote user equipment, wherein the PC5 and / or RRC message contains the first information of the second relay user equipment.

[0285] Step 6, after receiving the first information from the second relay user equipment, the second remote user equipment selects and / or reselects to the second relay user equipment.

[0286] Step 7, the second remote user equipment stores the cell of the second relay user equipment, that is, the first cell, as the camped cell.

[0287] Through the above method, it is ensured that the second node can update and store the information of the camped cell, thus ensuring that subsequently the second node can quickly connect to the base station to which the cell belongs.

[0288] Fig. 5E is a schematic diagram of yet another method a method of selection and / or reselection of a relay user equipment according to various embodiments of the present disclosure. As shown in Fig. 5E, in this method, one or more of the following steps 0 to 12 may be included.

[0289] Step 1, a first remote user equipment transmits a PC5 and / or RRC message to a first relay user equipment, wherein the PC5 and / or RRC message contains second information of the first remote user equipment.

[0290] Step 2, the first relay user equipment adds one to the hop count information contained in the received second information of the first remote user equipment, and / or adds the first relay user equipment identifier to the list of relay user equipment identifiers.

[0291] Step 3: The first relay user equipment transmits a PC5 and / or RRC message to the second relay user equipment, wherein the PC5 and / or RRC message contains the second information of the first relay user equipment.

[0292] Step 4, the second relay user equipment adds one to the hop count information contained in the received second information of the first relay user equipment, and / or adds the second relay user equipment identifier to the list of relay user equipment identifiers.

[0293] Step 5, the second relay user equipment transmits a PC5 and / or RRC message to the second remote user equipment, wherein the PC5 and / or RRC message contains the second information of the second relay user equipment.

[0294] Step 6, after receiving the second information of the second relay user equipment, the second remote user equipment transmits a PC5 and / or RRC message to the second relay user equipment, wherein the PC5 and / or RRC message contains the fourth information of the second remote user equipment.

[0295] Step 7, the second relay user equipment updates the hop count information after receiving the second information of the second remote user equipment; and / or if the second relay user equipment is a reference user equipment, the eleventh information is updated.

[0296] Step 8: the second relay user equipment transmits a PC5 and / or RRC message to the first relay user equipment, wherein the PC5 and / or RRC message contains the fourth information of the second relay user equipment.

[0297] Step 9: after receiving the fourth information from the second relay user equipment, the first relay user equipment selects and / or reselects to the second relay user equipment.

[0298] Step 10, the first relay user equipment updates the hop count information; and / or if the second relay user equipment is a reference user equipment, the eleventh information is updated.

[0299] Step 11: the first relay user equipment transmits a PC5 and / or RRC message to the first remote user equipment, and the PC5 and / or RRC message contains the fourth information of the first relay user equipment.

[0300] Step 12: after receiving the fourth information of the first relay user equipment, the first remote user equipment selects and / or reselects to the first relay user equipment.

[0301] Through the above method, the smooth / clear path between the first remote user equipment and the second remote user equipment is ensured by the way that each hop relay user equipment selects and / or reselects the next hop, thus ensuring that subsequently the first remote user equipment can be quickly connected to the second remote user equipment.

[0302] Fig. 6 is a block diagram of a node device according to an embodiment of the present disclosure.

[0303] A network node in the network can be used to implement the first node to the second node in the present invention. According to an embodiment, the node device illustrated in Fig. 6 ma comprises a remote UE, a relay UE, a peer remote UE, or a base station. Referring to Fig. 6, the node device according to the present invention includes a transceiver 510, a controller 520 and a memory 530. The transceiver 510, the controller 520 and the memory 530 are configured to perform the operations of the methods and / or embodiments of the present invention. Although the transceiver 510, the controller 520 and the memory 530 are shown as separate entities, they may be implemented as a single entity, such as a single chip. The transceiver 510, the controller 520 and the memory 530 may be electrically connected or coupled to each other. The transceiver 510 may transmit and receive signals to and from other network nodes. The controller 520 may include one or more processing units, and may control the network device to perform the operations and / or functions according to one of the above embodiments. The memory 530 may store instructions for implementing the operations and / or functions of one of the above embodiments described.

[0304] Those skilled in the art will understand that the illustrative embodiments described above are described herein and are not intended to be limiting. It should be understood that any two or more of the embodiments disclosed herein can be combined in any combination. In addition, other embodiments can be utilized and other changes can be made without departing from the spirit and scope of the subject matter presented herein. It will be readily understood that aspects of the present invention of the present disclosure, as generally described herein and shown in the accompanying drawings, can be arranged, substituted, combined, separated and designed in various different configurations, all of which are contemplated herein.

[0305] Those skilled in the art will understand that the various illustrative logical blocks, modules, circuits, and steps described in the present application can be implemented as hardware, software, or a combination of both. In order to clearly illustrate this interchangeability between hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in the form of their function set. Whether such a function set is implemented as hardware or software depends on the specific application and the design constraints imposed on the total / overall system. Skilled people can implement the described function set in different ways for each specific application, but such design decisions should not be interpreted as causing a departure from the scope of the present application.

[0306] The various illustrative logic blocks, modules, and circuits described in the present application can be implemented in a general-purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic devices, discrete gate or transistor logic, discrete hardware component, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0307] The steps of the method or technique described in the present application can be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. Software modules may camp in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, register, hard disk, removable disk, or any other form of storage media known in the art. An exemplary storage medium is coupled to a processor to enable the processor to read and write information from / to the storage medium. In the alternative, the storage medium may be integrated into the processor. The processor and storage medium may camp in an ASIC. The ASIC may camp in the UE. In the alternative, the processor and the storage medium may camp in the UE as discrete components.

[0308] In one or more exemplary designs, the described functions can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, each function can be stored on or transferred by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, which includes any media that facilitates the transfer of computer programs from one place to another. The storage medium may be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0309] What has been described above is only an exemplary embodiment of the present disclosure, and is not used to limit the protection scope of the present disclosure, which is determined by the appended claims.

Claims

1.A method performed by a first user equipment (UE) in a wireless communication system, the method comprising:identifying that a selection of a sidelink relay UE is triggered;selecting a second UE for the sidelink relay UE; andtransmitting, to the second UE, a message associated with the selection of the second UE.2.The method of claim 1, wherein the first UE is a first sidelink relay UE between a remote UE and a base station and the second UE is a second sidelink relay UE between the remote UE and the base station.3.The method of claim 1, wherein the second UE is selected among one or more UEs via a sidelink discovery procedure.4.The method of claim 1, wherein the selection is triggered based on at least one of an indication from an upper layer, a PC5 link signal quality, a PC5 radio link failure, or a PC5 connection release.5.The method of claim 1, wherein the message includes relay information of the first UE and cell information of the first UE.6.The method of claim 5, wherein the relay information comprises at least one of a UE identity of the first UE, hop count information, mobility related information, load information, or reference UE related information, andwherein the hop count information indicates a number of relay UEs between a remote UE and a base station.7.The method of claim 5, wherein the cell information comprises at least one of a physical cell identity, a cell global identity, or carrier frequency information.8.A first user equipment (UE) in a wireless communication system, the first UE comprising:a transceiver; anda controller coupled with the transceiver and configured to:identify that a selection of a sidelink relay UE is triggered,select a second UE for the sidelink relay UE, andtransmit, to the second UE, a message associated with the selection of the second UE.9.The first UE of claim 8, wherein the first UE is a first sidelink relay UE between a remote UE and a base station and the second UE is a second sidelink relay UE between the remote UE and the base station.10.The first UE of claim 8, wherein the second UE is selected among one or more UEs via a sidelink discovery procedure.11.The first UE of claim 8, wherein the selection is triggered based on at least one of an indication from an upper layer, a PC5 link signal quality, a PC5 radio link failure, or a PC5 connection release.12.The first UE of claim 8, wherein the message includes relay information of the first UE and cell information of the first UE.13.The first UE of claim 12, wherein the relay information comprises at least one of a UE identity of the first UE, hop count information, mobility related information, load information, or reference UE related information.14.The first UE of claim 13, wherein the hop count information indicates a number of relay UEs between a remote UE and a base station.15.The first UE of claim 8, wherein the cell information comprises at least one of a physical cell identity, a cell global identity, or carrier frequency information.

Images