METHOD AND APPARATUS FOR SIDELINK RELAY COMMUNICATIONS - Patent application

Abstract

Sidelink-based relay communication involves communication between a base station and a remote UE via a relay user equipment ("UE"). Relay communication can be improved by addressing incompatibilities between different devices supporting different functions / operations, such as layers of communication. Access control and establishment cause values ​​can also be addressed by relay communication. Paging identification and system information can be communicated by relay communication, such as via relay UE, to improve communication.

Description

[Technical Field]

[0001] This document relates generally to wireless communications, and more specifically to sidelink-based relay communications for device-to-device communications. [Background technology]

[0002] Wireless communication technology is moving the world toward an increasingly connected and networked society. Wireless communication relies on efficient network resource management and allocation between user mobile stations and radio access network nodes (including, but not limited to, radio base stations). New-generation networks are expected to provide high-speed, low-latency, and ultra-reliable communication capabilities and meet requirements from various industries and users. User mobile stations or user equipment ("UE") are becoming more complex, and the amount of data communicated is constantly increasing. With the development of wireless multimedia services, the demand for high-data-rate services and the system capacity and communication coverage requirements of traditional cellular networks are increasing. Furthermore, the use of cellular networks for public safety, social networking, short-range data sharing, local advertising, and other requirements for proximity services that allow people to communicate with nearby people or objects is also increasing. Device-to-device (D2D) communication technology can meet such demands. D2D communication improvements should be made to improve communication, meet the reliability requirements of vertical industries, and support new-generation network services. Summary of the Invention [Means for solving the problem]

[0003] This document relates to methods, systems, and devices for sidelink-based relay communication that extend communication coverage and improve network power consumption. Sidelink-based relay communication involves communication between a base station and a remote UE via a relay user equipment ("UE"). Relay communication, which may be referred to as UE-network relay operation, can be improved by addressing incompatibilities between different devices, which support different functions / operations, such as layers of communication. Access control and establishment cause values ​​can also be addressed by relay communication. Paging identification and system information can be communicated by relay communication, such as via a relay UE, to improve communication.

[0004] In one embodiment, a method for wireless communication includes receiving an indication of relay capabilities at Layer 2 or Layer 3 and acting as a relay based on the indication of relay capabilities. The indication is received by a relay user equipment ("UE") from a base station, and the relay UE acts as a relay between the relay UE and a remote UE. The relay capabilities include whether the base station can support only Layer 2 relay, only Layer 3, or both Layer 2 and Layer 3. The relay capabilities can support both Layer 2 and Layer 3, and the relay capabilities selected for the relay UE acting as a relay are based on a priority indication from the remote UE or from a higher layer in the relay UE. This operation as a relay includes sidelink discovery or sidelink communication. A system information block ("SIB") includes the indication.

[0005] In another embodiment, a method for wireless communication includes receiving an indication of relay capabilities at Layer 2 and Layer 3, checking authorization for UE-to-network relay discovery and communication based on the indication, and transmitting a sidelink relay configuration based on the relay capabilities and authorization. The indication is provided from a relay-enabled user equipment (“UE”) to a base station, and the base station checks the indication regarding the UE authorization status for UE-to-network relay discovery and communication.

[0006] In another embodiment, a method for wireless communication includes initiating a connection based on relay capabilities at Layer 2 or Layer 3, receiving an indication of a priority regarding relay capabilities between Layer 2 or Layer 3, and communicating based on the priority. The reception is from a relay user equipment (“UE”) acting as a relay between a base station and a remote UE. The indication is received from the remote UE, and communication is conducted to and from the remote UE.

[0007] In another embodiment, a method for wireless communication includes receiving an indication that a relay user equipment ("UE") is barred and, for UE-to-network relay operation, performing a reselection of the relay UE or suspending sidelink transmission with the relay UE. The indication that the relay UE is barred is based on a unified access control ("UAC").

[0008] In another embodiment, a method for wireless communication includes receiving information for paging monitoring of a remote user equipment ("UE"), monitoring paging occasions for the remote UE, and transmitting a paging indication to the remote UE based on the monitoring. The method further includes providing the information for paging monitoring to a relay UE in a PC5 message. The relay UE receives a paging message from a base station and receives a paging indication from the remote UE based on the monitoring from the remote UE. The monitoring and transmission are from the relay UE. The paging indication is delivered via a PC5 RRC message. The paging indication includes a radio access network ("RAN") paging or a core network ("CN") paging of the remote UE. The transmission includes forwarding the paging message to multiple remote UEs via groupcast.

[0009] In another embodiment, a method for wireless communication includes receiving a short message from a base station and forwarding information in the short message to a remote user equipment (“UE”). The forwarding occurs if systemInfoModification or etwsAndCmasIndication is set to 1. The reception is by a relay UE. The reception is from the base station.

[0010] In one embodiment, a wireless communications device comprises a processor and a memory, the processor configured to read code from the memory and to implement any of the above described embodiments.

[0011] In one embodiment, a computer program product includes a computer readable program medium code stored thereon, the code, when executed by a processor, causing the processor to implement any of the above-described embodiments.

[0012] In some embodiments, there is a wireless communication device comprising a processor and a memory, the processor configured to read code from the memory and perform any method described in any of the embodiments. In some embodiments, a computer program product includes computer readable program medium code stored thereon, the code, when executed by a processor, causing the processor to perform any method described in any of the embodiments. These and other aspects and implementations thereof are described in more detail in the drawings, specification, and claims. The present invention provides, for example, the following. (Item 1) 1. A method for wireless communication, the method comprising: receiving an indication of relay capability; acting as a relay based on said indication of said relay capability; and A method comprising: (Item 2) Item 1. The method of item 1, wherein the instruction is received from a base station by a relay user equipment (“UE”), the relay UE acting as the relay between the base station and a remote UE. (Item 3) Item 3. The method according to item 2, wherein the relay capability includes that the base station can support only Layer 2 relay, can support only Layer 3 relay, can support both Layer 2 relay and Layer 3 relay, or is not allowed to relay. (Item 4) Item 3. The method of item 3, wherein if the relay capability can support both Layer 2 and Layer 3, the relay capability selected for the relay UE acting as the relay is based on a priority indication from the remote UE or from a higher layer of the relay UE. (Item 5) Item 1. The method of item 1, wherein the functioning as a relay includes sidelink discovery or sidelink communication for relay operation. (Item 6) Item 10. The method of item 1, wherein a system information block ("SIB") includes the instruction. (Item 7) 1. A method for wireless communication, the method comprising: receiving an indication of relay capability; checking authorization for UE-network relay discovery and communication based on the instruction; and transmitting a sidelink relay configuration based on the relay capability and the authorization; and A method comprising: (Item 8) Item 8. The method of item 7, wherein the relay capability can be Layer 2 relay only, Layer 3 relay only, or both Layer 2 relay and Layer 3 relay, and the indication is provided from a relay-enabled user equipment ("UE") to a base station, and the base station checks the indication regarding UE authorization status for the UE-to-network relay. (Item 9) 1. A method for wireless communication, the method comprising: sending a relay instruction to a relay user equipment (“UE”) or base station; Acting as a remote UE based on the instruction; A method comprising: (Item 10) 10. The method of claim 9, wherein the transmitting is from the remote UE. (Item 11) 10. The method of claim 9, wherein the indication includes that the remote UE supports only L2, only L3, or both L2 and L3. (Item 12) 10. The method of claim 9, further comprising receiving a relay selection policy from an upper layer or 5GC or RAN, the relay selection policy indicating a preference for an L2 relay or an L3 relay. (Item 13) 10. The method of claim 9, wherein the acting as the remote UE based on the instruction of the relay includes sidelink discovery or sidelink communication for relay operation. (Item 14) 1. A method for wireless communication, the method comprising: receiving an indication that a relay user equipment ("UE") is barred; For UE-network relay operation, reselecting the relay UE or suspending sidelink transmission with the relay UE. A method comprising: (Item 15) Item 15. The method of item 14, wherein the indication that the relay UE is barred is based on unified access control ("UAC"). (Item 16) 1. A method for wireless communication, the method comprising: monitoring paging occasions for a remote UE; sending a paging indication to the remote UE based on the monitoring; and A method comprising: (Item 17) Item 17. The method of item 16, further comprising receiving information for paging monitoring of a remote user equipment (“UE”) in a PC5 message. (Item 18) Item 17. The method of item 16, wherein the relay UE receives a paging message from a base station when monitoring paging occasions for the remote UE. (Item 19) Item 17. The method of item 16, wherein the monitoring and the transmitting are from a relay UE. (Item 20) Item 17. The method of item 16, wherein the paging indication is delivered via a PC5 RRC message. (Item 21) Item 17. The method of item 16, wherein the paging indication includes a radio access network ("RAN") paging or a core network ("CN") paging of the remote UE. (Item 22) Item 17. The method of item 16, wherein the transmitting includes forwarding the paging message to multiple remote UEs via groupcast. (Item 23) 1. A method for wireless communication, the method comprising: receiving a short message from a base station; forwarding the information in the short message to a remote user equipment ("UE"); A method comprising: (Item 24) Item 24. The method of item 23, wherein the forwarding occurs if systemInfoModification or etwsAndCmasIndication is set to 1. (Item 25) 24. The method of claim 23, wherein the receiving is by a relay UE. (Item 26) 24. The method of claim 23, wherein the receiving is from a base station. (Item 27) 27. A wireless communication device comprising a processor and a memory, the processor configured to read a code from the memory and to perform a method according to any one of items 1 to 26. (Item 28) 27. A computer program product comprising a computer-readable program medium code stored thereon, the code causing the processor to perform a method according to any one of items 1 to 26 when executed by a processor. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 shows an exemplary base station. [Figure 2] FIG. 2 illustrates an exemplary random access (RA) messaging environment. [Figure 3] FIG. 3 illustrates an exemplary device-to-device messaging environment. [Figure 4] Figure 4 shows the user plane protocol stack for Layer 2 relay communication. [Figure 5] Figure 5 shows the user plane protocol stack for Layer 3 relay communication. [Figure 6A] FIG. 6a shows relay communication for a base station supporting Layer 2. [Figure 6B] FIG. 6b shows relay communication for a base station supporting Layer 3. [Figure 6C] FIG. 6c illustrates relay communication for a base station that supports both Layer 2 and Layer 3. [Figure 6D] FIG. 6d illustrates relay communication for a base station that does not support layer 2 or layer 3. [Figure 7] FIG. 7 shows relay communication for sending relay instructions to the base station. [Figure 8] FIG. 8 shows relay communication for transmitting destination identification information to a base station. [Figure 9A] FIG. 9a illustrates relay communication for sending a relay instruction to a base station that supports Layer 2. [Figure 9B] FIG. 9b shows relay communication for sending a relay instruction to a base station that supports Layer 3. [Figure 9C] FIG. 9c illustrates relay communication for sending relay instructions to a base station that supports both layer 2 and layer 3. [Figure 10] FIG. 10 shows relay communication with establishment threshold setting. [Figure 11] FIG. 11 shows relay communication including access restrictions. [Figure 12] FIG. 12 shows relay communication with paging indication. [Figure 13] FIG. 13 shows relay communication with paging for system information. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present disclosure will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific embodiments. It should be noted, however, that the present disclosure may be embodied in a variety of different forms, and therefore, the subject matter embraced or claimed should not be construed as limited to any of the embodiments set forth below.

[0015] Throughout this specification and claims, terms may have nuanced meanings suggested or implied in context beyond their explicitly stated meaning. Similarly, the phrases "in one embodiment" or "in some embodiments" used herein do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" used herein do not necessarily refer to different embodiments. The phrases "in one embodiment" or "in some embodiments" used herein do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" used herein do not necessarily refer to different embodiments. For example, the claimed subject matter is intended to include, in whole or in part, example embodiments or combinations of embodiments.

[0016] Generally, terms may be understood, at least in part, from their use in context. For example, terms such as "and," "or," or "and / or" as used herein may include a variety of meanings that may depend, at least in part, on the context in which such terms are used. Typically, "or," when used to relate a list such as A, B, or C, is intended to mean A, B, and C, which are used here in an inclusive sense, and A, B, or C, which are used here in an exclusive sense. Furthermore, the terms "one or more" or "at least one" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending, at least in part, on the context. Similarly, terms such as "a," "an," or "the" may be understood to convey singular usage or to convey plural usage, depending, at least in part, on the context. Furthermore, the terms "based on" or "determined by" may be understood not to necessarily convey an exclusive set of factors, but instead may allow for the existence of additional factors not necessarily explicitly described, depending, at least in part, on the context.

[0017] Radio Resource Control ("RRC") is a protocol layer at the IP level between a UE and a base station (network layer). Various Radio Resource Control (RRC) states may exist, such as an RRC connected (RRC_CONNECTED) state, an RRC inactive (RRC_INACTIVE) state, and an RRC idle (RRC_IDLE) state. RRC messages are transmitted via the Packet Data Convergence Protocol ("PDCP"). A UE can transmit infrequent (periodic and / or aperiodic) data in the RRC_INACTIVE state without moving to the RRC_CONNECTED state. This can save UE power consumption and signaling overhead. This can be through a random access channel ("RACH") protocol scheme or a configuration grant ("CG") scheme. The communication described herein may be specific to relay communication, which may also be referred to as device-to-device communication ("D2D") or sidelink communication.

[0018] D2D or relay communication can reduce the burden on cellular networks, reduce user equipment ("UE") power consumption, increase data rates, and improve network infrastructure robustness, all of which can meet the demands of high-data-rate and proximity services. Relay communication or D2D technology may also be referred to as proximity services ("ProSe") or sidelink communication. The interface between devices is known as or may be referred to as a PC5 interface. PC5 is when a UE communicates directly with another UE over a direct channel without a base station. In some embodiments, sidelink-based relay communication may be applied to indoor relay communication, smart farming, smart factories, and public safety services. Figure 3 illustrates an exemplary embodiment for sidelink communication. Figures 1-2 illustrate an exemplary base station, user equipment, and messaging environment that may be applicable to sidelink communication.

[0019] 1 illustrates an exemplary base station 102. A base station may also be referred to as a radio network node. The base station 102 may be further identified as a nodeB (NB, e.g., eNB or gNB) in the context of mobile communications. The exemplary base station may include radio Tx / Rx circuitry 113 for transmitting to and receiving from user equipment (UE) 104. The base station may also include network interface circuitry 116 (e.g., optical or wired interconnect, Ethernet, and / or other data transmission medium / protocol) for coupling the base station to a core network 110.

[0020] The base station may also include system circuitry 122. The system circuitry 122 may include a processor 124 and / or a memory 126. The memory 126 may include operations 128 and control parameters 130. The operations 128 may include instructions for execution by one or more of the processors 124 to support the functionality of the base station. For example, these operations may process random access transmission requests from multiple UEs. The control parameters 130 may include parameters that support the execution of the operations 128. For example, the control parameters may include network protocol settings, random access message formatting rules, bandwidth parameters, radio frequency mapping assignments, and / or other parameters.

[0021] 2 illustrates an exemplary random access messaging environment 200. In the random access messaging environment, a UE 104 may communicate with a base station 102 over a random access channel 252. In this example, the UE 104 supports one or more subscriber identity modules (SIMs), such as SIM1 202. An electrical and physical interface 206 connects SIM1 202 to the rest of the user equipment hardware, for example, via a system bus 210.

[0022] The mobile device 200 includes a communications interface 212, a system logic 214, and a user interface 218. The system logic 214 may include any combination of hardware, software, firmware, or other logic. The system logic 214 may be implemented, for example, by one or more systems on a chip (SoC), application-specific integrated circuits (ASICs), discrete analog and digital circuits, and other circuits. The system logic 214 is part of the implementation of any desired functionality in the UE 104. In that regard, the system logic 214 may include, for example, logic to facilitate: decoding and playing music and video, such as MP3, MP4, MPEG, AVI, FLAC, AC3, or WAV decoding and playback; running applications; accepting user input; storing and retrieving application data; establishing, maintaining, and terminating data connections, such as for cellular phone calls or Internet connections; establishing, maintaining, and terminating wireless network connections, Bluetooth connections, or other connections; and displaying related information on the user interface 218. The user interface 218 and input 228 may include a graphical user interface, a touch-sensitive display, haptic feedback or other tactile output, voice or facial recognition input, buttons, switches, speakers, and other user interface elements. Further examples of input 228 may include microphones, video and still image cameras, temperature sensors, vibration sensors, rotation and orientation sensors, headset and microphone input / output jacks, universal serial bus (USB) connectors, memory card slots, radiation sensors (e.g., IR sensors), and other types of inputs.

[0023] The system logic 214 may include one or more processors 216 and a memory 220. The memory 220 stores, for example, control instructions 222 that the processor 216 executes to perform desired functions for the UE 104. Control parameters 224 provide and specify configuration and operation options for the control instructions 222. The memory 220 may also store any BT, WiFi, 3G, 4G, 5G, or other data 226 that the UE 104 transmits (or receives) via the communication interface 212. In various embodiments, system power may be provided by a power storage device, such as a battery 282.

[0024] In the communications interface 212, radio frequency (RF) transmit (Tx) and receive (Rx) circuitry 230 handles the transmission and reception of signals via one or more antennas 232. The communications interface 212 may include one or more transceivers. The transceiver may be a wireless transceiver that includes modulation / demodulation circuitry, digital-to-analog converters (DACs), shaping tables, analog-to-digital converters (ADCs), filters, waveform shapers, filters, preamplifiers, power amplifiers, and / or other logic for transmitting and receiving via one or more antennas or (for some devices) over a physical (e.g., wired) medium.

[0025] The transmitted and received signals may conform to any of a diverse array of formats, protocols, modulations (e.g., QPSK, 16-QAM, 64-QAM, or 256-QAM), frequency channels, bit rates, and coding. As one specific example, communication interface 212 may include a transceiver supporting transmission and reception under 2G, 3G, BT, WiFi, Universal Mobile Telecommunications System (UMTS), High Speed ​​Packet Access (HSPA)+, and 4G / Long Term Evolution (LTE) standards. However, the techniques described below are applicable to other wireless communication technologies, whether arising from the 3rd Generation Partnership Project (3GPP), GSM Association, 3GPP2, IEEE, or other partnerships or standards bodies.

[0026] FIG. 3 illustrates an exemplary device-to-device messaging environment. Device-to-device ("D2D") messaging may also be referred to as sidelink messaging, sidelink communication, sidelink relay, or relay communication. FIG. 3 illustrates a base station ("BS") having a communication range 304. A second user equipment ("UE2") is within the communication range 304 of the BS, and a first user equipment ("UE1") is outside the communication range 304. UE1 and UE2 establish relay communication 302, in which UE2 is the relay UE and UE1 is the remote UE. In relay communication, the remote UE (UE1) communicates with the network through the relay UE (UE2). The relay UE (UE2) relays communication between the base station (BS) and the remote UE (UE1). In some embodiments, relay communication may be designed for UE1 in an area with weak or no communication coverage. UE1 is enabled to communicate with the base station BS through the relay UE (UE2). This extends the coverage area of ​​network 304 to include relay coverage area 302 (including UE1), increasing the capacity of the network.

[0027] In some embodiments, such as during an emergency (e.g., an earthquake), a cellular network may operate abnormally or the sidelink communication range of the network may need to be extended. Therefore, relay communication may be designed to allow multiple UEs to communicate with each other through a relay UE. Although not shown, there may be multiple UEs in a relay communication chain, or a relay UE may have multiple remote UEs. The interface in FIG. 3 between the UE and the BS during relay communication is referred to as the Uu interface.

[0028] There are at least two technology schemes for relay communication, involving the Internet Protocol ("IP") layer (Layer 3 or "L3") and the access layer (Layer 2 or "L2"). Layer 3-based relays forward data according to the UE's IP information (e.g., IP address or IP port number). Layer 2-based relays route and forward user plane and control plane data at the access layer, allowing network operators (i.e., core networks and / or BSs) to more effectively manage remote UEs. The mechanisms for New Radio ("NR") sidelink communication differ from those of previous versions of sidelink communication (e.g., in frame structure, quality of service handling, bearer configuration, bearer establishment, etc.). Figures 4 through 9c relate to handling L2 and L3 coexistence and control plane procedures for supporting L2 and L3 relay.

[0029] Figure 4 shows the user plane protocol stack for Layer 2 ("L2") relay communication. L2 is also referred to as the access layer. For L2 UE-to-network relay, an adaptation layer ("ADAPT" in Figure 4) may be located above the radio link control ("RLC") sublayer in the Uu interface between the relay UE and the base station (labeled nNB). The Uu Service Data Adaptation Protocol ("SDAP") / Packet Data Convergence Protocol ("PDCP") and Radio Resource Control ("RRC") terminate between the remote UE and the base station, and the radio link control ("RLC"), MAC, and PHY terminate at each link, e.g., between the remote UE and the relay UE and between the relay UE and the base station.

[0030] Figure 5 shows the user plane protocol stack for Layer 3 ("L3") relay communication. L3 is also known as the Internet Protocol ("IP") layer. The L3 relay provides a generic L3 forwarding function that can relay any type of IP traffic between the remote UE and the network. The base station may not be aware of the presence of the remote UE at L3. The remote UE's traffic may be treated as relay UE's traffic. (Base station layer support)

[0031] Both L2 and L3 relay communication are supported in 5G NR. However, different base stations, relay UEs, and remote UEs may support different types of relay operation, which may affect cell selection and relay selection. Specifically, the base station, relay UE, and remote UE may support only L2 or only L3, may support both L2 and L3, or may support neither L2 nor L3. Based on the compatibility of this support, relay communication may be changed. This may be referred to as relay compatibility or layer compatibility. Figures 6a to 8 relate to changing a base station's support (for L2 and / or L3).

[0032] FIG. 6a illustrates relay communication for a base station that supports Layer 2. If the base station supports L2 relay, the base station may be able to support L3 relay, since in some embodiments, L3 relay only requires the base station to configure some thresholds for relay discovery and selection. However, network operators may establish different policies for UE-to-network relay support. Some operators may prefer stricter network control, which may result in support for L2 relay but not L3 relay. In this example, the base station may indicate that L3 relay is not allowed. Additionally, the base station may explicitly indicate that it allows L2 relay, as shown in FIG. 6a. The base station provides a relay indication indicating support for L2 user-to-network ("U2N") relay. The relay indication may also indicate that L3 U2N relay is not supported. The relay indication can be used to enable L2-capable relay UEs to initiate discovery transmission / reception. To enable RRC_IDLE / RRC_INACTIVE relay UEs to detect the relay type supported by the base station, the base station may broadcast a relay indication via the system information block ("SIB").

[0033] Figure 6b illustrates relay communication for a base station that supports Layer 3. If a network operator prefers less network control for UE-to-network relay, the base station may be implemented to support only L3 relay. In this example, as shown in Figure 6b, the base station may indicate that L2 relay is not allowed, and the base station may explicitly indicate that L3 relay is allowed. The base station may broadcast an L3 relay indication via a system information block ("SIB"). An L3 relay-enabled UE may initiate a relay discovery procedure and act as a relay when necessary.

[0034] Figure 6c illustrates relay communication for a base station that supports both Layer 2 and Layer 3. The relay indication indicates that the base station supports both L2 relay and L3 relay. The base station may broadcast the L2 relay indication and the L3 relay indication. For a relay UE, the relay UE may send its L2 and / or L3 relay indication to the base station. For example, for an L2 relay-capable relay UE, when it sends an L2 relay indication to the base station, the base station may configure a Uu RLC channel for the relay UE. Alternatively, if the UE is capable of both L2 relay and L3 relay and the UE wants to function as both an L2 relay and an L3 relay, the UE may send both an L2 relay and an L3 relay indication to the base station, as in Figures 6c and 7.

[0035] FIG. 7 illustrates relay communication for sending a relay indication to a base station. A relay indication 702 is sent from the relay UE to the base station for L2 and L3 indication. The base station then checks UE authorization 704 to determine whether the relay UE is authorized for L2 or L3 relay communication. The UE authorization status may include ProSe direct discovery and ProSe direct communication (i.e., as a 5G ProSe UE for ProSe direct discovery, as a 5G ProSe UE for ProSe direct communication), UE-network relay discovery and communication (i.e., as a 5G ProSe Layer 2 remote UE, as a 5G ProSe Layer 2 UE-network relay, or as a Layer 3 UE-network relay). If the relay UE is capable of L3 relay, the base station may send a sidelink Tx resource configuration 706 to the UE. If the UE is capable of L2 relay, the gNB may send a sidelink Tx resource configuration 706 and a Uu RLC channel configuration 706 to the relay UE. The Uu RLC channel can be used by the relay UE to forward the SRB0 / 1 / 2 / 3 signaling of the remote UE to the base station.

[0036] FIG. 8 illustrates relay communication for transmitting destination identification information to a base station. When the relay UE reports the remote UE's destination L2 ID 802 to the base station via a SidelinkUEInformation message, the relay UE may indicate which destination L2 ID is for the L2 remote UE. Based on this information, the base station may assign a local ID 804 for the L2 remote UE for subsequent remote UE traffic forwarding, as shown in FIG. 8. In another embodiment, the relay UE may report the remote UE's destination L2 ID together with the local L2 ID assigned by the relay UE to the base station via the SidelinkUEInformation message. Based on this information, the base station may associate the L2 local ID with the remote UE's destination L2 ID.

[0037] If the remote UE is capable of both L2 and L3 relay communication, the remote UE may send an indication of layer priority. The remote UE may prioritize L2 or L3 remote UE. The priority may be communicated to the base station. The base station may know the priority based on the UE authorization (704 in FIG. 7). However, the base station may not know the L3 capabilities of the remote UE. In an example, if the remote UE prefers L3 and indicates this preference to the base station, the base station may not consider a potential path switch for the remote UE. Service continuity may depend on the implementation of the remote UE.

[0038] Figure 6d illustrates relay communication for a base station that does not support Layer 2 or Layer 3. The relay indication indicates that the base station does not support either L2 or L3 relay. In one embodiment, this lack of support may not be broadcast by the base station. Rather, support is explicitly broadcast, with the absence of a broadcast indicating a lack of support. In some embodiments, the base station may prohibit autonomous L3 relaying based on pre-configuration. To do so, the base station may indicate that UE-to-network relaying is not permitted. This relay indication can be used to prohibit an L3 relay-capable UE from acting as a UE-to-network relay if the L3 relay-capable UE is served by a base station (i.e., a base station that is pre-configured not to support that relaying).

[0039] If L3 UE-to-Network Relay is not prohibited, the L3 relay-enabled UE may initiate a relay discovery procedure via a pre-configured sidelink ("SL") configuration. In this embodiment, a non-access layer ("NAS") authorization for L3 relay may be used. The base station may not receive UE authorization status such as 5G ProSe Layer 2 Remote UE, 5G ProSe Layer 2 UE-to-Network Relay, or Layer 3 UE-to-Network Relay. The base station may not actually recognize the L3 relay. (User Device Layer Support)

[0040] 9a-9c illustrate relay communication related to UE relay capabilities. Specifically, some UEs may support only L2, only L3, both L2 and L3, or neither. UE relay layer capabilities vary for individual UEs, resulting in different capabilities for remote and relay UEs. The relay service code included in the relay discovery message may indicate whether the UE-to-network relay is an L3 relay or an L2 relay. In some embodiments, an L2 remote UE may select a relay UE when the relay service code indicates L2 relay support. Similarly, an L3 remote UE may select a relay UE when the relay service code indicates L3 relay support. For a relay UE capable of both L2 and L3 relay, it may broadcast separate relay discovery messages, which include different relay service codes for L2 relay indication and L3 relay indication, respectively. If the remote UE is capable of both L2 and L3, the remote UE may select either an L2 relay UE or an L3 relay UE. When both an L2 relay UE and an L3 relay UE are available, whether the L2 relay or the L3 relay should be selected may be determined by the implementation of the remote UE. Alternatively, the remote UE may receive a relay selection policy from the upper layer / 5GC / RAN that may indicate an L2 relay priority or an L3 relay priority. When an L2 relay indication is received, the remote UE may prioritize the L2 relay selection.

[0041] FIG. 9a illustrates relay communication for sending a relay instruction to a base station that supports Layer 2. Specifically, the relay UE supports only L2 relay. In this embodiment, the relay UE transmits a discovery message 902 including a relay service code indicating that it is an L2 relay. When a remote UE accesses this relay UE and indicates that it is an L2 U2N relay in an L2 link establishment message (e.g., a PC5 RRC message), the relay UE knows that it is for relay purposes and can then initiate an RRC connection with the base station. This connection can be initiated using a new establishment cause value. The relay UE can indicate to the base station that the remote UE is an L2 remote UE and that a local remote UE ID should be assigned by the base station. In other embodiments, the relay UE notifies the remote UE about the local remote UE ID assigned by the relay UE. In some embodiments, the local remote UE ID can be configured in the remote UE via a Uu RRC or PC5 RRC message.

[0042] 9b shows relay communication for sending a relay indication to a base station that supports Layer 3. The relay UE supports only L3 relay. In this embodiment, the relay UE transmits a discovery message 904 including a relay service code indicating that it is an L3 relay. When a remote UE accesses this relay UE and indicates that it is an L3 U2N remote UE in an L2 link establishment message / PC5 RRC message, the relay UE knows that it is for relay purposes and can initiate an RRC connection with the base station (e.g., using a new establishment cause value).

[0043] FIG. 9c illustrates relay communication for transmitting a relay indication to a base station that supports both Layer 2 and Layer 3. The relay UE supports both L2 and L3 relays, as evidenced by the relay service code transmitted with the relay indication. In an alternative embodiment, the same relay UE may transmit a separate discovery message (not shown) to indicate its support for L2 or L3 relays. For nearby remote UEs, they may access the relay UE for L2 or L3 relays, respectively. The remote UE may send its L2 remote UE and / or L3 remote UE capability indication 906 to the relay UE for the relay UE to determine the remote UE's supported relay type. In some embodiments, the remote UE may select whether to access an L2 or L3 relay. The remote UE transmits a relay service code in an L2 link establishment message, which can be used by the relay UE to identify the L2 or L3 remote UE's access. Alternatively, if the L2 relay UE ID is different for the L2 or L3 relay, the L2 relay UE ID may be used to identify whether the L2 or L3 remote UE accesses the relay. (Probability Cause Value)

[0044] During RRC establishment or resumption (at L2), the relay UE may indicate an establishment cause value for the base station to decide whether to accept or reject the request. Upon receiving the first RRC message from the remote UE, the relay UE may perform its own connection establishment / resumption process if it did not start in RRC_CONNECTED. The relay UE can indicate to the base station that its establishment / resumption cause is to relay traffic of the remote UE. The establishment / resumption cause value of the relay UE can be set differently in different embodiments described below.

[0045] In one embodiment, an existing establishment / restart cause value can be reused. In one example, the relay UE may set the establishment / restart value at the AS layer based on the cause value provided by the upper layer.

[0046] Figure 10 illustrates another example of relay communication with the setting of an establishment default value. The relay UE may set the establishment / resume cause in the AS layer with the same value as in the RRCsetuprequest / RRCresumeRequest message 1002 received from the remote UE. The RRCsetuprequest / RRCresumeRequest message may be part of the signaling radio bearer SRB0 message, which may be unencrypted. The relay UE may detect the establishment / resume cause value 1004 from the first RRC message delivered over the PC5 RLC channel using the fixed specification. The relay UE may perform its own connection establishment / resume 1006 and set the establishment / resume cause with the detected value 1008.

[0047] The relay UE may obtain the establishment / resumption value via PC5 signaling with the remote UE. In one example, the remote UE may send the establishment / resumption cause value to the relay UE via an RRCConfigurationSidelink message before the remote UE sends the first RRC message to the relay UE. Once the relay UE acquires the establishment / resumption cause of the remote UE, the relay UE may initiate its own RRC connection setup / resumption using the corresponding establishment / resumption cause.

[0048] In another embodiment, there may be a new establishment / restart cause value for the relay UE. In one example, a new AS layer establishment / restart cause value such as "relay" or "remote UE establishment via relay" or "remote UE resume via relay" may be designed. Upon receiving the "relay" establishment / restart cause, the base station may prioritize the connection setup for the relay UE. This establishment / restart cause value may be set at the AS layer without the involvement of higher layers.

[0049] In another example, if a remote UE detects a Uu / PC5 radio link failure ("RLF"), the remote UE may reselect a relay UE and send an RRCReestablishment request to the base station for Uu recovery. When a relay UE is in an RRC IDLE / INACTIVE state, it may need to establish / restart its own RRC connection. Potential cause values ​​in the RRCReestablishment request include reconfigurationFailure, handoverFailure, and otherFailure, although the establishment / restart cause values ​​may be extended to include reconfigurationFailure, handoverFailure, and / or otherFailure. Alternatively, the indication may be "remote UE reestablishment by relay" as one establishment / restart cause value.

[0050] In another example, another way of designing the establishment / restart cause values ​​includes remote-UE-emergency, remote-UE-highPriorityAccess, remote-UE-mt-Access, remote-UE-mo-Signalling, remote-UE-mo-Data, remote-UE-mo-VoiceCall, remote-UE-mo-VideoCall, remote-UE-mo-SMS, remote-UE-mps-PriorityAccess, remote-UE-mcs-PriorityAccess, remote-UE-rna-Update, remote-UE-reconfigurationFailure, remote-UE-handoverFailure, and / or remote-UE-otherFailure. While exemplary, there may be limitations on the reserve values ​​for the establishment definition that limit the potential exemplary values. For example, there may be only six reserve values ​​for the establishment cause and five reserve values ​​for the restart cause, which would limit new establishment / restart cause values. Another example embodiment is to add a new IE to the RRCSetupRequest and RRCResumeRequest messages, which may indicate a relay and a legacy cause to set the establishment / resumption cause value for the remote UE. (relay access)

[0051] For L2 UE-to-network relay, the relay UE may provide unified access control ("UAC") parameters to the remote UE. Access control checks are performed at the remote UE using the parameters of the cell the remote UE is attempting to access. The relay UE may not perform access control checks for the remote UE's data. There may be access attempts that prohibit checks associated with a given access category ("AC") and one or more access identifiers ("AIs"). Given that the relay UE may include communications from other remote UEs, there must be a process for configuring an AC for the relay UE when the relay UE is attempting to access the network solely for relaying purposes and not for its own services.

[0052] In one embodiment, there may be a new access category ("AC") for relay UEs. There may be a higher priority for the AC of a relay UE that is specifically used for relay communication. For example, the prohibition factors associated with this new AC may be configured to always allow relay access.

[0053] In another embodiment, there may be an existing AC that is reused, for example, an existing AC 8 (e.g., MO signaling at the RRC level that originates from other than paging). The prioritization for the existing AC may need to be changed so that access is granted for relay UEs attempting access only for relay communication.

[0054] In another embodiment, the relay UE may receive an AC from the remote UE over the PC5 interface. This AC may be used for the relay UE's UAC. This alternative embodiment may rely on PC5 signaling extensions. In some examples, even if the same AC is used for the relay UE and the remote UE, the relay UE and the remote UE may have different UAC barring results due to the generated random number.

[0055] In some embodiments, a remote UE may not be barred while an associated relay UE is barred. In this example, the remote UE may essentially be barred. If an access attempt is barred for the relay UE, the T390 timer ((0.7+0.6*rand)*uac-BarringTime) may be started. The relay UE may not attempt access until the T390 time expires and the barring is removed. Alternatively, when the remote UE sends an RRCSetupRequest / RRCResumeRequest message, the remote UE may start the T300 / T319 timers. If the T300 / T319 timers expire, the remote UE may notify upper layers regarding a failure to establish an RRC connection, at which point the procedure ends. The T300 / T319 timers may expire during the relay UE's barring time, and therefore the relay UE may send a PC5 indication to the remote UE regarding the UAC barring and / or barring timers.

[0056] FIG. 11 illustrates relay communication including access restrictions. Barring parameters (for access restrictions such as AC) are transmitted to the remote UE for the base station 1102. In the example of FIG. 11, the remote UE is not barred 1104, and the relay UE is barred 1106. The relay UE provides an indication of being barred 1108. Upon receiving such an indication, the remote UE may reselect another relay UE 1110. Alternatively, the remote UE may pause the T300 / T319 timers, which can be restarted when another PC5 indication is received from the relay UE indicating the lifting of the relay UE's UAC barring.

[0057] In an alternative embodiment, a new AC and / or AI may be defined for dedicated UAC control of the relay UE. In this example, a mapping table may be specified between the AI / AC and the established values. The RAN may configure a separate set of AC parameters for the new AC or AI. (Relay Paging)

[0058] Paging operations in the network may operate differently for relay communications. A paging occasion (“PO”) message source must be determined. For example, to monitor the PO of a remote UE on behalf of the remote UE, a relay UE may obtain the PO information of the remote UE. The frame in which the UE wakes up may be called a paging frame (“PF”). Within a radio frame, there may be subframes, and the UE does not stay awake in all 10 subframes. The UE may wake up in a specific subframe within the paging frame, called a paging occasion (“PO”).

[0059] In one embodiment, PO may be calculated as follows: [Table 1]

[0060] The UE may use discontinuous reception ("DRX") in the RRC_IDLE and RRC_INACTIVE states to reduce power consumption. The UE may monitor one paging occasion ("PO") per DRX cycle. A PO may be a set of PDCCH monitoring opportunities having multiple subframes. The PF and PO may be determined by a UE-specific DRX cycle T and UE_ID value and a cell-specific Ns, N, and PF_offset value. To monitor the PO of the remote UE, the relay UE may obtain at least the DRX cycle T and UE_ID information of the remote UE. Regarding the UE_ID, there are several alternative embodiments for obtaining the remote UE's identification information: UE_ID. Options include transmitting the 5G-S-TMSI of the remote UE, utilizing a pseudo UE ID (e.g., 5G-S-TMSI mod 1024) of the remote UE, or calculating the PO of the remote UE.

[0061] In one embodiment, the 5G-S-TMSI is also used to page the remote UE in the paging message, so the relay UE can accurately determine whether the remote UE is being paged. Otherwise, the relay may not be able to determine the specific remote UE indicated in the received paging message. In this embodiment, the relay UE sends the received paging message within the PO to the remote UE. However, disclosing the 5G-S-TMSI may present a potential security risk because the remote UE's 5G-S-TMSI may be revealed to the relay UE over the PC5 interface. Furthermore, an RRC_INACTIVE remote UE may send an I-RNTI (Radio Network Temporary Identifier) ​​to the relay UE, allowing the relay UE to determine the RAN-based Notification Area ("RNA") paging of the remote UE.

[0062] Figure 12 shows relay communication with paging indication. If there are no security concerns, the 5G-S-TMSI / I-RNTI of the remote UE can be provided directly to the relay UE. In this example, the relay UE can accurately determine whether the associated remote UE is being paged by monitoring the remote UE's PO 1204 and, if a page is available, receiving a paging message 1202. If a page is available, the relay UE can send a paging indication 1206 (CN paging, RAN paging) to the specific remote UE. The paging indication can be delivered via a PC5 RRC message or MAC CE.

[0063] If there is a security concern about exposing the 5G-S-TMSI / I-RNTI of the remote UE to the relay UE, the relay UE will only recognize the 5G-S-TMSI mod 1024 and will not recognize the I-RNTI. In this example, the relay UE may receive a paging message in the associated PO, but the relay UE may not determine whether the associated relay UE is being paged or not.

[0064] The relay UE can forward the entire paging message received in the PO to the associated remote UE. For example, the PO message can be delivered to the remote UE via an RRC container in a PC5 message. Alternatively, if the relay UE knows the RRC state of the remote UE, the relay UE can only send RAN paging to RRC_INACTIVE remote UEs and CN paging to RRC_IDLE remote UEs. Considering that multiple remote UEs may need to receive the same paging message (e.g., mapped to the same PO), the relay UE may design a new destination L2 ID to be used for groupcasting paging messages over the PC5 interface. The relay UE may inform the remote UE of this destination L2 ID for paging when the remote UE establishes a connection with the relay UE or when the remote UE requests the relay UE to forward paging for the remote UE. (Short message in relay communication)

[0065] The short message may be transmitted on the Physical Downlink Control Channel ("PDCCH") using the Short Message field of Downlink Control Information ("DCI") format 1_0, with or without an associated paging message, using the P-RNTI (Radio Network Temporary Identifier). The following table identifies example short messages: [Table 2]

[0066] Any RRC_CONNECTED UE, not just RRC_IDLE / INACTIVE UEs, can monitor short messages to detect System Information ("IS") change indications and Earthquake and Tsunami Warning System (ETWS) and Commercial Mobile Alert System (CMAS) notifications. Regarding the stopPagingMonitoring short message, it can be used by a relay UE to stop paging monitoring in this PO. This short message can apply to all UEs interested in this PO. In some embodiments of paging messages, an RRC_IDLE / INACTIVE UE can be the only UE that monitors and receives.

[0067] For remote UEs, the remote UE may not directly monitor short messages over the Uu interface. However, the relay UE may be notified of potential changes via systemInfoModification and / or etwsAndCmasIndication and receive updated SIB or SI messages. For RRC_CONNECTED remote UEs that support on-demand SI acquisition, they may obtain updated SIBs from the base station because the base station knows which SIBs are of interest to or requested by the remote UE.

[0068] Figure 13 illustrates relay communication with paging for system information. When the SIB is updated, the base station may push updates 1302, 1304 to the remote UE. If the base station does not support pushing SI updates, the relay UE may forward systemInfoModification and etwsAndCmasIndication (1302, 1304) over the PC5 interface as shown in Figure 13. Based on these indications, the remote UE may receive the updated SIB via on-demand SI acquisition.

[0069] For an RRC_IDLE / INACTIVE remote UE, the remote UE may inform the relay UE that it is ETWS-capable, CMAS-capable, or may directly inform the relay UE about SIBs that it is interested in. When a relay UE detects an SI change that an associated remote UE is interested in, the relay UE forwards the corresponding SIB to the remote UE.

[0070] For an RRC_Connected remote UE, the base station may transmit the updated SI or SIB6 / 7 / 8 directly to the remote UE via dedicated Uu RLC signaling if the base station is aware of the remote UE's ETWS / CMAS capability or SIBs of interest. In this example, the relay UE does not need to monitor the PO of the RRC_Connected remote UE. Alternatively, if the SI change instruction and ETWS / CMAS notification are sent in the remote UE's PO, it may be that the same instruction is also sent in the relay UE's PO. In this embodiment, the relay UE may monitor the PO of only RRC_IDLE / INACTIVE remote UEs.

[0071] An RRC_Connected UE may request an SIB when an SI message with onDemandSIB-Request set and containing the required SIB and si-BroadcastStatus set to notbroadcasting is sent. The UE may send a DedicatedSIBRequest message to the base station. When it becomes an RRC_Connected remote UE, it may be interested in SIBs set to notbroadcasting. In this example, the RRC_Connected remote UE also sends a SIB request to the relay UE, which monitors the SIBs and sends the obtained SIBs to the remote UE via a PC5 message. (PC5 RLF / UU RLF / Relay UE HO / Impact of Relay UE restarting relay reselection)

[0072] For PC5 Radio Link Failure ("RLF"), if a remote UE detects an RLF on the PC5 link with the current relay UE, a relay reselection may be triggered. For L3 relay, another relay UE may be directly reselected and a PC5 connection may be established. There may be no service continuity extension at the AS layer.

[0073] For L2 relays, once the cell ID is broadcast in the discovery message, the L2 remote UE can reselect a new relay UE served by the same cell as the old relay UE. In this example, the L2 remote UE may perform an RRC re-establishment procedure to restore the Uu RRC connection with the base station ("gNB"). To support this example, when the base station receives a PC5 RLF report from the old relay UE, the base station should not immediately release the remote UE's context. Instead, the base station may retain the remote UE's context for potential re-establishment.

[0074] When a remote UE performs RRC Reestablishment, it may send an RRCReestablishmentRequest message. The remote UE fills in the C-RNTI, PCI, and short MAC-I. When the remote UE initially connects to a base station via a relay UE, the base station can assign a cell-specific remote UE Id (e.g., C-RNTI 16 bits) to the remote UE via a Uu RRC Reconfiguration / RRCSetup message. In another example, the PCI can be sent to the remote UE via a PC5 RRC message from the original relay UE or via a Uu RRC message from the old base station. In this way, the remote UE can recover at the new base station.

[0075] The base station may assign a C-RNTI to the remote UE via a Uu RRC reconfiguration message. Furthermore, the C-RNTI of the remote UE can be transmitted to the relay UE via PC5 (remote UE transmitted to relay UE) or Uu (base station transmitted to remote UE). The C-RNTI of the remote UE can be used in the adaptation layer of PC5 and Uu.

[0076] Regarding Uu Radio Link Failure ("RLF") handover ("HO"), when a Uu RLF is detected by a relay UE, the relay UE may send a PC5-S message to its connected remote UE, which may trigger a relay reselection. In another example, considering that the relay UE may recover the Uu link with the base station, it may not be necessary for the remote UE to reselect another relay UE or to immediately switch to the Uu link (especially for RRC_IDLE / INACTIVE remote UEs that have no ongoing data transmission). The potential handling of a remote UE during a Uu RLF can be divided into the following two examples:

[0077] 1) RRC_CONNECTED remote UE: During this period, the relay UE may send a Uu RLF notification to the RRC_CONNECTED remote UE, which may trigger relay reselection. Alternatively, the remote UE may initiate a relay discovery procedure to find a suitable nearby relay UE. After a period of time, if the relay UE recovers its Uu link at the original base station, the relay UE may send an RLF recovery notification to the remote UE, which continues PC5 transmission with this relay UE. In another example, if the relay UE recovers its Uu link at a new base station or if the relay UE's Uu RLF recovery fails, the relay UE may send a Uu recovery in a new base station notification to its connected remote UE, which may trigger the RRC_CONNECTED remote UE to switch to a direct Uu link or reselect another relay UE.

[0078] 2) RRC_IDLE / INACTIVE Remote UE: An RRC_IDLE / INACTIVE remote UE may maintain a PC5 connection with the relay UE if the relay UE detects a Uu RLF and performs Uu RRC recovery. Assuming the relay UE recovers its Uu link at a new base station, the relay UE can still serve the RRC_IDLE / INACTIVE remote UE to forward CN / RAN paging. In another example, if the relay UE's Uu link recovery fails, the relay UE enters RRC_IDLE. The relay UE can still forward CN / RAN paging for the RRC_IDLE / INACTIVE remote UE.

[0079] Therefore, an RRC_Connected remote UE can reselect another relay as soon as possible if a Uu RLF is detected by a connected relay UE. For an RRC_IDLE / INACTIVE remote UE, the remote UE may maintain a PC5 connection with the relay UE even if the relay UE detects an RLF and enters the RRC_IDLE state. The relay UE may only need to send a Uu RLF notification / PC5-Smessage to an RRC_CONNECTED remote UE.

[0080] Considering that the relay UE may recover the Uu link with the base station, the relay UE may send Uu RLF notifications such as detected Uu RLF, recovered Uu RLF, Uu recovery failed, Uu recovery at new base station, etc., which can be used by the remote UE to determine whether and when relay / cell reselection should be performed.

[0081] If the relay UE detects a Uu RLF, it may only need to send an RLF notification / PC5-Smessage to an RRC_CONNECTED remote UE. For RRC_IDLE / INACTIVE remote UEs, even if the relay UE enters RRC_IDLE state, it may still keep the PC5 connection and receive paging forwarding from the relay UE.

[0082] For RRC resumption at a new base station, when the UE moves from RRC_INACTIVE to RRC_INACTIVE, the current K gNB and K. RRCint It may be necessary to store inactive AS context such as the key, robust header compression ("ROHC") state, stored quality of service ("QoS") to data radio bearer (DRB) mapping rules, C-RNTI used in the source PCell, cellIdentity and physical cell identity of the source PCell, spCellConfigCommon (if configured) in the PSCell's ReconfigurationWithSync, and all other parameters configured except those in the PCell's ReconfigurationWithSync and servingCellConfigCommonSIB. In another example, the UE resets the MAC, releases the default MAC cell group configuration if present, re-establishes the RLC entity for SRB1, suspends all SRBs and DRBs except SRB0, and indicates Packet Data Convergence Protocol (PDCP) suspension to lower layers for all DRBs. When the UE enters RRC_INACTIVE, PDCP entities are retained and RLC entities are released. However, RLC-related configurations may be retained. The base station may only provide the delta configuration when the UE moves from RRC_INACTIVE to RRC_CONNECTED.

[0083] In another example, if the UE plans to resume the RRC connection with Uu and before transmitting the RRCResumeRequest, it may check the RRC configuration, RoHC state, stored QoS flow to DRB mapping rules, and K from the stored UE inactive AS context. gNB and K. RRCint Restore the key and gNB and K. RRCint Upon receiving the RRCResume message from the base station, the UE may update the MCGCellGroup configuration, radio bearer configuration, resume SRB2 / SRB3 / DRB, and enter the RRC_CONNECTED state.

[0084] With respect to the relay UE, the adaptation layer configuration at the relay UE may include bearer mapping configuration, local ID of the associated RRC_Connected remote UE, PO / 5G-S-TMSI / I-RNTI of the associated remote UE, etc.

[0085] Regarding the base station, the base station may store the SRB / DRB configuration of the relay UE and the local ID of the associated RRC_Connected remote UE as the context of the relay UE. For RRC_IDLE / INACTIVE remote UEs, the base station may not store the associated NG / Uu context of these remote UEs. However, if an RRC_IDLE remote UE maintains a PC5 connection with an RRC_Connected remote UE, the base station may still maintain the destination L2 ID of such remote UE. Furthermore, the base station may also know that this destination L2 ID is associated with the remote UE. The base station may assign a local remote UE ID before this remote UE, potentially for subsequent Uu RRC signaling transfers.

[0086] From the base station's perspective, for an RRC_INACTIVE remote UE, the base station may at least store the SRB / DRB configuration of the remote UE. Furthermore, if a PC5 connection is maintained between an RRC_Connected relay UE and an RRC_INACTIVE remote UE, the base station may store an association between the RRC_Connected relay UE and the remote UE. When an RRC_INACTIVE remote UE reselects another RRC_Connected relay UE, the serving base station of the other relay UE may store the association between the RRC_Connected relay UE and the remote UE as one of the contents of the relay UE's context. In another example, when an RRC_INACTIVE remote UE reselects another RRC_INACTIVE relay UE and establishes a PC5 connection, the base station may not store the association between the RRC_INACTIVE relay UE and the RRC_INACTIVE remote UE.

[0087] An RRC_INACTIVE relay UE may perform RRC resumption upon receiving the first RRC signaling of a remote UE. Whether the relay UE performs its RRC resumption at the original base station or a new base station, the relay UE may first resume its RRC connection and then forward the first RRC signaling of the remote UE to the base station. Because the base station does not store the context of the RRC_INACTIVE relay UE and its associated remote UE, there is no need to consider the context acquisition issue of both the remote UE and the relay when the relay UE performs RRC resumption at the new base station.

[0088] A remote UE connected to an RRC_INACTIVE relay UE can be in RRC_IDLE or RRC_INACTIVE state. For an RRC_IDLE / INACTIVE remote UE, it can keep the PC5 connection and receive paging forwarding from the relay UE, regardless of whether the relay UE resumes the RRC connection in a new base station. It may not be necessary to trigger relay (re)selection for the connected remote UE.

[0089] When an RRC_INACTIVE relay UE resumes an RRC connection at a new base station, the connected RRC_IDLE / INACTIVE remote UEs may maintain a PC5 connection and receive paging forwarding from the relay UE.

[0090] The RRC resumption of the remote UE and the relay UE can be performed independently. When the relay UE performs RRC resumption in a new base station, it may not be necessary to consider the context acquisition issue of both the remote UE and the relay UE. (Resource Discovery used by remote UE)

[0091] Relay UEs and Remote UEs (ICs) in RRC CONNECTED may use discovery configuration provided via dedicated signaling if available. Relay UEs and Remote UEs (ICs) in RRC IDLE or RRC INACTIVE shall use discovery configuration provided by SIB if available.

[0092] A relay UE supporting L3 UE-Network Relay is enabled to transmit discovery messages based at least on preconfiguration when connected to a base station that is not capable of sidelink relay operation if its serving carrier is not shared with the carrier for sidelink operation. A sidelink-capable base station may broadcast at least a sidelink SIB. The sidelink SIB should include the sidelink Rx resource pool and, optionally, the sidelink Tx resource pool. If the sidelink SIB is not available, the relay / remote UE may consider the base station as a non-sidelink-capable base station and then use preconfiguration for discovery if the base station's serving carrier is not shared with the carrier for sidelink operation.

[0093] If a sidelink SIB is not provided by the base station, the relay / remote UE may consider the base station as a non-sidelink capable base station and use preconfiguration for discovery when the base station's serving carrier is not shared with a carrier for sidelink operation.

[0094] For sidelink-capable base stations, the UE shall not perform new radio ("NR") sidelink communication according to SL-V2X-Preconfiguration if it detects a cell that provides an NR sidelink configuration or an inter-carrier NR sidelink configuration for the frequencies on which the UE is interested in performing NR sidelink communication. For UE-network relays, if the discovery pre-configured sidelink carrier is neither the serving carrier of the sidelink-capable base station nor included in the NR sidelink configuration in SIB12, the relay / remote UE may use the pre-configuration for discovery. If the discovery pre-configured sidelink carrier is neither the serving carrier of the sidelink-capable base station nor included in the NR sidelink configuration in SIB12, the relay / remote UE may use the pre-configuration for discovery.

[0095] Furthermore, if a UE detects at least one cell on a frequency for which it is configured to perform NR sidelink communication when the UE satisfies the S criterion, the UE shall consider itself within coverage for NR sidelink communication on that frequency. Otherwise, it shall consider itself out of coverage for NR sidelink communication on that frequency. For an out-of-coverage L3 remote UE, it may only use a preconfigured sidelink discovery configuration. However, for an L2 OOC remote UE, it may use a network-configured sidelink discovery configuration if it is connected to a sidelink-capable base station. A sidelink-capable base station may provide better network control for the remote UE. Otherwise, it may use a preconfigured sidelink discovery configuration.

[0096] The sidelink discovery Tx resource configuration in the SIB may only be used by RRC_IDLE / INACTIVE UEs, while the discovery Tx resource configuration via dedicated signaling may only be used by RRC_CONNECTED UEs. If an RRC_CONNECTED relay / remote UE is unable to obtain the sidelink discovery Tx resource configuration from the sidelink-capable base station via dedicated signaling, it may be due to a relay / remote UE authentication failure or sidelink resource congestion. In this example, the RRC_CONNECTED relay / remote UE may not use the discovery Tx resource configuration from the SIB. The RRC_CONNECTED relay / remote UE may use the sidelink discovery Tx resource configuration provided by dedicated signaling.

[0097] The systems and processes described above may be encoded on a computer-readable medium, such as a signal-carrying medium or memory, programmed into one or more integrated circuits, one or more processors, or processed by a controller or computer. The data may be analyzed in a computer system and used to generate a spectrum. If the method is implemented by software, the software may reside in non-volatile or volatile memory in communication with or interfaced to a storage device, synchronizer, communication interface, or transmitter. The circuit or electronic device is designed to transmit data to another location. The memory may contain an ordered list of executable instructions for performing a logic function. The described logic function or any system element may be implemented via optical circuits, digital circuits, source code, analog circuits, analog sources such as analog electrical signals, audio signals, video signals, or any combination thereof. The software may be embodied in any computer-readable or signal-carrying medium for use by or in connection with an instruction-executable system, apparatus, or device. Such a system may include a computer-based system, a system including a processor, or another system that may selectively fetch instructions from an instruction-executable system, apparatus, or device that may also execute instructions.

[0098] "Computer-readable medium," "machine-readable medium," "propagating signal" medium, and / or "signal-bearing medium" may include any device that stores, communicates, propagates, or transports software for use by or in connection with an instruction-executable system, apparatus, or device. The machine-readable medium may be, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. A non-exhaustive list of examples of machine-readable media includes an electrical connection "electronic" having one or more wires, a portable magnetic or optical disk, random access memory "RAM," read-only memory "ROM," volatile memory such as erasable programmable read-only memory (EPROM or flash memory), or optical fiber. Machine-readable media may also include tangible media on which software is printed, as the software may be stored electronically as an image or in another format (e.g., via optical scanning) and then compiled and / or interpreted, or otherwise processed. The processed medium may then be stored in computer and / or machine memory.

[0099] The illustrations of the embodiments described herein are intended to provide a general understanding of the structures of various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments will be apparent to those skilled in the art upon reviewing this disclosure. Other embodiments may be utilized and derived from this disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Furthermore, the figures are merely representative and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Therefore, the disclosure and the figures should be considered illustrative and not limiting.

[0100] One or more embodiments of the present disclosure may be individually and / or collectively referred to herein by the term "invention" merely for convenience, and without any intention to intentionally limit the scope of the present application to any particular invention or inventive concept. Furthermore, while specific embodiments have been illustrated and described herein, it should be understood that any subsequent configurations designed to achieve the same or similar purpose may be substituted for the specific embodiment shown. The present disclosure is intended to cover any and all subsequent adaptations or modifications of the various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those skilled in the art upon review of the description.

[0101] The term "coupled" is defined to mean directly connected to, or indirectly connected through, one or more intermediate components. Such intermediate components may include both hardware-based and software-based components. Changes in the arrangement and type of components may be made without departing from the spirit or scope of the claims set forth herein. Additional, different, or fewer components may be provided.

[0102] The subject matter disclosed above should be considered illustrative rather than limiting, and the appended claims are intended to cover all such modifications, extensions, and other embodiments that fall within the true spirit and scope of the invention. Accordingly, to the maximum extent permitted by law, the scope of the invention should be determined by the broadest permissible interpretation of the following claims and their equivalents, and should not be restricted or limited by the foregoing detailed description. While various embodiments of the invention have been described, it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention should not be limited in light of the appended claims and their equivalents.

Claims

Claim 1: A method for wireless communication implemented by a relay user equipment (UE), the method comprising: receiving, from a base station, a first indication of relay capabilities indicating which of Layer 2 relay and / or Layer 3 relay are supported by the base station; transmitting, from the relay UE to the base station, a second indication of relay capabilities indicating which of the Layer 2 relay and / or Layer 3 relay are supported by the relay UE; acting as a relay based on the first instruction; A method comprising:

2. The method described in claim 1, wherein the relay UE acts as the relay between the base station and the remote UE.

3. The method described in claim 2, wherein the relay capability of the base station includes the base station being capable of supporting only Layer 2 relay, being capable of supporting only Layer 3 relay, being capable of supporting both Layer 2 relay and Layer 3 relay, or not being allowed to relay.

4. The method described in claim 3, wherein, if the relay capabilities of the relay UE and the base station can support both Layer 2 and Layer 3, the network layer selected for the relay UE to function as the relay is based on a third indication of priority from the remote UE or from a higher layer of the relay UE.

5. 2. The method of claim 1, wherein the acting as a relay comprises sidelink discovery or sidelink communication for relay operation.

6. The method of claim 1, wherein the first instruction is included in a system information block (SIB).

7. checking authorization for UE-network relay discovery and communication based on the first indication; sending a sidelink relay configuration based on the relay capability and the authorization of the relay UE to a remote UE; The method of claim 1 further comprising:

8. The method described in claim 7, wherein the relay capability of the relay UE can be Layer 2 relay only, Layer 3 relay only, or both Layer 2 relay and Layer 3 relay, and the second instruction is provided to the base station, and the base station checks the UE authorization status for the UE-network relay.

9. A user equipment (UE) for wireless communication, the UE comprising: a memory for storing instructions; and at least one processor, the at least one processor: receiving, from a base station, a first indication of relay capabilities indicating which of Layer 2 relay and / or Layer 3 relay are supported by the base station; transmitting, from the relay UE to the base station, a second indication of relay capabilities indicating which of the Layer 2 relay and / or Layer 3 relay are supported by the relay UE; acting as a relay based on the first instruction; The UE is configured to execute instructions for:

10. The UE described in Claim 9, wherein the relay UE functions as the relay between the base station and a remote UE.

11. The UE of claim 10, wherein the relay capabilities of the base station include the base station being capable of supporting only Layer 2 relay, being capable of supporting only Layer 3 relay, being capable of supporting both Layer 2 relay and Layer 3 relay, or not being allowed to relay.

12. A UE as described in claim 11, wherein, when the relay capabilities of the relay UE and the base station can support both Layer 2 and Layer 3, the network layer selected for the relay UE to function as the relay is based on a third indication of priority from the remote UE or from a higher layer of the relay UE.

13. The UE of claim 9, wherein the at least one processor is configured to execute instructions to function as the relay by performing sidelink discovery or sidelink communication for relay operation.

14. The UE of claim 9, wherein the first instruction is included in a system information block (SIB).

15. The at least one processor: checking authorization for UE-network relay discovery and communication based on the first indication; sending a sidelink relay configuration based on the relay capability and the authorization of the relay UE to a remote UE; The UE of claim 9 , further configured to execute instructions to:

16. The UE described in claim 15, wherein the relay capability of the relay UE can be Layer 2 relay only, Layer 3 relay only, or both Layer 2 relay and Layer 3 relay, and the second instruction is provided to the base station, and the base station checks the UE authorization status for the UE-network relay.

Images