Method and apparatus for triggering sidelink relay radio link control channel release

Abstract

The invention discloses a method and a device for first-end user equipment. In one embodiment, a first end user equipment establishes a PC5 connection with a relay user equipment for supporting inter-user equipment relay communication between the first end user equipment and a second end user equipment via the relay user equipment. The first end user equipment serves a first end-to-end-side link data radio bearer using a first PC5 relay radio link control channel and a second end-to-end-side link data radio bearer using a second PC5 relay radio link control channel. In addition, the first end user equipment releases the first PC5 relay radio link control channel in response to determining to serve the first end-to-end-side link data radio bearer and the second end-to-end-side link data radio bearer using the second PC5 relay radio link control channel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 563,025, filed March 8, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] The present disclosure relates generally to wireless communication networks, and more particularly, to a method and apparatus for triggering a sidelink relay Radio Link Control (RLC) channel release in inter-UE relay communication in a wireless communication system. Background Art

[0003] With the rapidly growing demand for transferring large amounts of data to and from mobile communication devices, traditional mobile voice communication networks have evolved into networks that use Internet Protocol (IP) data packets. This IP packet communication can provide IP-based voice, multimedia, multicast, and on-demand communication services to users of mobile communication devices.

[0004] An exemplary network architecture is the Evolved Universal Terrestrial Radio Access Network (E-UTRAN). The E-UTRAN system can provide high data throughput to enable the aforementioned IP-based voice and multimedia services. Currently, the 3GPP standards organization is discussing new next-generation (e.g., 5G) new radio technologies. Consequently, changes to the current body of 3GPP standards are currently being submitted and considered to evolve and complete the 3GPP standards. Summary of the Invention

[0005] The present invention discloses a method and apparatus for a first-end user equipment (UE). In one embodiment, the first-end UE establishes a PC5 connection with a relay UE to support inter-UE relay communication between the first-end UE and the second-end UE via the relay UE. The first-end UE also establishes a first end-to-end sidelink (SL) data radio bearer (DRB), and associates the first end-to-end SL DRB with a first PC5 relay radio link control (RLC) channel to support inter-UE relay communication, wherein the first PC5 relay RLC channel is established between the first-end UE and the relay UE. The first-end UE further establishes a second end-to-end SL DRB, and associates the second end-to-end SL DRB with a second PC5 relay RLC channel to support inter-UE relay communication, wherein the second PC5 relay RLC channel is established between the first-end UE and the relay UE. In addition, the first-end UE determines to use the second PC5 relay RLC channel to provide services for the first end-to-end SL DRB and the second end-to-end SL DRB. In addition, in response to determining to use the second PC5 relay RLC channel to serve the first end-to-end SL DRB and the second end-to-end SL DRB, the first-end UE releases the first PC5 relay RLC channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 A diagram of a wireless communication system is shown according to an exemplary embodiment.

[0007] Figure 2 is a block diagram of a transmitter system (also referred to as an access network) and a receiver system (also referred to as a user equipment or UE) according to an exemplary embodiment.

[0008] Figure 3 is a functional block diagram of a communication system according to an exemplary embodiment.

[0009] Figure 4 According to an exemplary embodiment Figure 3 Functional block diagram of the program code.

[0010] Figure 5 It is 3GPP TS23.304V18.4.0 Figure 4 .Reproduction of 2.8-1.

[0011] Figure 6 It is 3GPP TS23.304V18.4.0 Figure 6 .Reproduction of 3.2.4.2-1.

[0012] Figure 7It is 3GPP TS23.304V18.4.0 Figure 6 .Reproduction of 3.2.4.3-1.

[0013] Figure 8 It is 3GPP TS23.304V18.4.0 Figure 6 .Reproduction of 4.3.1-1.

[0014] Figure 9 It is 3GPP TS23.304V18.4.0 Figure 6 .Reproduction of 4.3.2-1.

[0015] Figure 10 It is 3GPP TS23.304V18.4.0 Figure 6 .Reproduction of 4.3.4-1.

[0016] Figure 11 It is 3GPP TS23.304V18.4.0 Figure 6 .7.2-1 reappearance.

[0017] Figure 12 It is 3GPP TS23.304V18.4.0 Figure 6 .7.3.2-1 reappearance.

[0018] Figure 13 It is 3GPP TS23.304V18.4.0 Figure 6 .7.3.3-1 reappearance.

[0019] Figure 14 It is 3GPP TS 38.300V18.0.0 Figure 16 .Reproduction of 12.2.2-1.

[0020] Figure 15 It is 3GPP TS 38.300V18.0.0 Figure 16 .Reproduction of 12.2.2-2.

[0021] Figure 16 It is 3GPP TS 38.300V18.0.0 Figure 16 .Reappearance of 12.7-1.

[0022] Figure 17 It is 3GPP TS 38.331V18.0.0 Figure 5 .8.9.1.1-1 reappearance.

[0023] Figure 18 It is 3GPP TS 38.331V18.0.0 Figure 5.8.9.1.1-2 reappearance.

[0024] Figure 19 It is 3GPP TS 38.331V18.0.0 Figure 5 .8.9.11.1-1 reappearance.

[0025] Figure 20 is a flow chart according to an exemplary embodiment.

[0026] Figure 21 is a flow chart according to an exemplary embodiment.

[0027] Figure 22 is a flow chart according to an exemplary embodiment. DETAILED DESCRIPTION

[0028] The exemplary wireless communication systems and devices described below employ wireless communication systems that support broadcast services. Wireless communication systems are widely deployed to provide various types of communications, such as voice, data, etc. These systems can be based on code division multiple access (CDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), 3GPP Long Term Evolution (LTE) radio access, 3GPP Long Term Evolution Advanced (LTE-A or LTE-Advanced), 3GPP2 Ultra Mobile Broadband (UMB), WiMax, 3GPP New Radio (NR), or some other modulation technology.

[0029] Specifically, the exemplary wireless communication systems and devices described below may be designed to support one or more standards, such as those provided by an alliance named “3rd Generation Partnership Project” referred to herein as 3GPP, including: TS 23.304 V18.4.0, “Proximity based Service (ProSe) in 5G System (5GS) (Release 18)”; TS 38.300 V18.0.0, “NR; NR and NG-RAN Overall Description; Stage 2 (Release 18)”; TS 38.331 V18.0.0, “NR; Radio Resource Control (RRC) Protocol Specification (Release 18)”; and 3GPP email discussion [Post125]

[402] [Relay] 38.331 Rel-18 Relay CR (Huawei), “Draft_38.331_CR4549r1_(Rel-18)_RRC corrections_v2 Rapp.docx”. The standards and documents listed above are hereby expressly incorporated by reference in their entirety.

[0030] Figure 1 The multiple access wireless communication system according to one embodiment of the present invention is shown. An access network 100 (AN) includes multiple antenna groups, one including 104 and 106, another including 108 and 110, and another including 112 and 114. Figure 1 In the figure, only two antennas are shown for each antenna group; however, each antenna group may utilize more or fewer antennas. Access terminal 116 (AT) communicates with antennas 112 and 114, where antennas 112 and 114 transmit information to access terminal 116 via forward link 120 and receive information from access terminal 116 via reverse link 118. Access terminal (AT) 122 communicates with antennas 106 and 108, where antennas 106 and 108 transmit information to access terminal (AT) 122 via forward link 126 and receive information from access terminal (AT) 122 via reverse link 124. In an FDD system, communication links 118, 120, 124, and 126 may use different frequencies for communication. For example, forward link 120 may use a different frequency than that used by reverse link 118.

[0031] Each group of antennas and / or the area in which they are designed to communicate is often referred to as a sector of the access network. In an embodiment, the antenna groups are each designed to communicate with access terminals in a sector of the area covered by the access network 100.

[0032] In communications on forward links 120 and 126, the transmit antennas of access network 100 may utilize beamforming to improve the signal-to-noise ratio of the forward links for the different access terminals 116 and 122. Additionally, an access network that uses beamforming to transmit to access terminals randomly dispersed throughout its coverage area may cause less interference to access terminals in neighboring cells than an access network that transmits to all of its access terminals through a single antenna.

[0033] An access network (AN) may be a fixed station or base station for communicating with a terminal and may also be referred to as an access point, Node B, base station, enhanced base station, evolved Node B (eNB), network node, network, or some other terminology. An access terminal (AT) may also be referred to as user equipment (UE), a wireless communication device, terminal, access terminal, or some other terminology.

[0034] Figure 2 is a simplified block diagram of an embodiment of a transmitter system 210 (also referred to as an access network) and a receiver system 250 (also referred to as an access terminal (AT) or user equipment (UE)) in a MIMO system 200. At the transmitter system 210, traffic data for a number of data streams is provided from a data source 212 to a transmit (TX) data processor 214.

[0035] In one embodiment, each data stream is transmitted through a respective transmit antenna. TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

[0036] The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme selected for that data stream (e.g., BPSK, QPSK, M-PSK, or M-QAM) to provide modulation symbols. The data rate, coding, and modulation used for each data stream may be determined by instructions executed by processor 230.

[0037] The modulation symbols for all data streams are then provided to a TX MIMO processor 220, which may further process the modulation symbols (e.g., for OFDM). The TX MIMO processor 220 then converts the N T The modulation symbol streams are provided to N Ttransmitters (TMTR) 222a through 222t. In certain embodiments, TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

[0038] Each transmitter 222 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions the analog signals (e.g., amplifies, filters, and upconverts them) to provide a modulated signal suitable for transmission over the MIMO channel. T The antennas 224a to 224t transmit N signals from transmitters 222a to 222t. T a modulated signal.

[0039] At the receiver system 250, N R The transmitted modulated signals are received by each antenna 252a through 252r and the received signal from each antenna 252 is provided to a respective receiver (RCVR) 254a through 254r. Each receiver 254 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream.

[0040] RX data processor 260 then extracts the N R The receiver 254 receives and processes N R received symbol streams to provide N T The RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by the RX data processor 260 is complementary to that performed by the TX MIMO processor 220 and the TX data processor 214 at the transmitter system 210.

[0041] Processor 270 periodically determines which precoding matrix to use (discussed below). Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion.

[0042] The reverse link message may include various types of information about the communication link and / or the received data stream. The reverse link message is then processed by TX data processor 238, which also receives traffic data for several data streams from data source 236, modulated by modulator 280, conditioned by transmitters 254a through 254r, and transmitted back to transmitter system 210.

[0043] At transmitter system 210, the modulated signal from receiver system 250 is received by antenna 224, conditioned by receiver 222, demodulated by demodulator 240, and processed by RX data processor 242 to extract the reverse link message transmitted by receiver system 250. Processor 230 then determines which precoding matrix to use to determine the beamforming weights and then processes the extracted message.

[0044] Steering Figure 3 , this figure shows an alternative simplified functional block diagram of a communication device according to one embodiment of the present invention. Figure 3 As shown in FIG. 1 , the communication device 300 in the wireless communication system can be used to implement Figure 1 UE (or AT) 116 and 122 in or Figure 1 The base station (or AN) 100 in the wireless communication system is preferably an NR system. The communication device 300 may include an input device 302, an output device 304, a control circuit 306, a central processing unit (CPU) 308, a memory 310, a program code 312, and a transceiver 314. The control circuit 306 executes the program code 312 in the memory 310 through the CPU 308, thereby controlling the operation of the communication device 300. The communication device 300 can receive signals input by the user through the input device 302 (such as a keyboard or a keypad), and can output images and sounds through the output device 304 (such as a monitor or a speaker). The transceiver 314 is used to receive and transmit wireless signals, deliver the received signals to the control circuit 306, and wirelessly output the signals generated by the control circuit 306. The communication device 300 in the wireless communication system can also be used to implement Figure 1 AN 100 in.

[0045] Figure 4 According to one embodiment of the present invention Figure 3 3. A simplified block diagram of program code 312 is shown in FIG. In this embodiment, program code 312 includes an application layer 400, a layer 3 portion 402, and a layer 2 portion 404, and is coupled to a layer 1 portion 406. Layer 3 portion 402 typically performs radio resource control. Layer 2 portion 404 typically performs link control. Layer 1 portion 406 typically performs physical connectivity.

[0046] 3GPP TS23.304 introduces the following: 4.2.8 5G ProSe Inter-UE Relay Reference Architecture Figure 4 .2.8-1 shows the Layer 2 and Layer 3 5G ProSe inter-UE relay reference architecture. 5G ProSe UEs communicate with each other via the 5G ProSe inter-UE relay. [3GPP TS23.304V18.4.0 titled "Reference Architecture for 5G ProSe Inter-UE Relay" Figure 4 .2.8-1 reproduced as Figure 5 ] Each 5G ProSe end UE and 5G ProSe inter-UE relay can have a subscription from the same PLMN or different PLMNs. […] 5.8.4 Identifiers for 5G ProSe Inter-UE Relay Discovery 5.8.4.1 Overview The 5G ProSe inter-UE relay discovery message contains two identifier sets, namely the direct discovery set and the inter-UE relay discovery set. - The direct discovery identifier set is part of the content of the 5G ProSe direct discovery message, as defined in clause 5.8.1. -The Inter-UE Relay Discovery Identifier Set contains extended information supporting 5G ProSe Inter-UE Relay discovery and direct discovery. The 5G ProSe inter-UE relay shall modify the inter-UE relay discovery identifier set and forward the direct discovery identifier set and the inter-UE relay discovery identifier set during the discovery procedure. 5.8.4.2 Common Identifiers for 5G ProSe Inter-UE Relay Discovery The following parameters are used for the 5G ProSe Inter-UE Relay Discovery Notification message (Model A), where the source layer 2 ID and destination layer 2 ID are used to send and receive the message, and the user information ID and relay service code are included in the message: - Source Layer 2 ID: The 5G ProSe Inter-UE Relay selects the source Layer 2 ID for the 5G ProSe Inter-UE Relay Discovery Notification message. - Destination Layer 2 ID: The destination Layer 2 ID for the 5G ProSe Inter-UE Relay Discovery Notification message is selected based on the configuration as described in clause 5.1.5.1. -User Information ID of 5G ProSe Inter-UE Relay: Provides information about 5G ProSe Inter-UE Relay. -5G ProSe UE user information ID list: provides information about 5G ProSe UE. -Relay Service Code: Information used to indicate the connectivity service provided by the 5G ProSe inter-UE relay for the 5G ProSe end UE. The following parameters are used for the 5G ProSe Inter-UE Relay Discovery Solicitation message (Model B) between the discoverer 5G ProSe end UE and the 5G ProSe Inter-UE Relay, where the source Layer 2 ID and the destination Layer 2 ID are used to send and receive the message, and the user information ID and relay service code are included in the message: - Source Layer 2 ID: The discoverer 5G ProSe UE selects the source Layer 2 ID for relaying the discovery request message between 5G ProSe UEs. - Destination Layer 2 ID: The destination Layer 2 ID for the 5G ProSe Inter-UE Relay Discovery Solicitation message is selected based on the configuration as described in clause 5.1.5.1. -User information ID of the discoverer 5G ProSe UE: provides information about the discoverer 5G ProSe UE. -User information ID of the discovered 5G ProSe UE: provides information about the discovered 5G ProSe UE. -Relay Service Code: Information about the connectivity services that the discoverer 5G ProSe-side UE is interested in. The following parameters are used for the 5G ProSe Inter-UE Relay Discovery Response message (Model B) between the discoverer 5G ProSe-side UE and the 5G ProSe Inter-UE Relay, where the source Layer 2 ID and the destination Layer 2 ID are used to send and receive the message, and the user information ID and relay service code are included in the message: - Source Layer 2 ID: The 5G ProSe Inter-UE Relay selects the source Layer 2 ID for the 5G ProSe Inter-UE Relay Discovery Response message. - Destination Layer 2 ID: set to the source Layer 2 ID of the received 5G ProSe Inter-UE Relay Discovery Request message. -User information ID of the discovered 5G ProSe UE: provides information about the discovered 5G ProSe UE. -User Information ID of 5G ProSe Inter-UE Relay: Provides information about 5G ProSe Inter-UE Relay. -Relay Service Code: identifies the connectivity service provided by the 5G ProSe inter-UE relay to the 5G ProSe end UE. It matches the relay service code from the corresponding discovery request message. The following parameters are used for the 5G ProSe Inter-UE Relay Discovery Solicitation message (Model B) between the 5G ProSe Inter-UE Relay and the discoverer 5G ProSe end UE, where the source layer 2 ID and the destination layer 2 ID are used to send and receive the message, and the user information ID and relay service code are included in the message: - Source Layer 2 ID: The 5G ProSe Inter-UE Relay selects the source Layer 2 ID for the 5G ProSe Inter-UE Relay Discovery Request message. - Destination Layer 2 ID: The destination Layer 2 ID for the 5G ProSe Inter-UE Relay Discovery Solicitation message is selected based on the configuration as described in clause 5.1.5.1. -User information ID of the discoverer 5G ProSe UE: provides information about the discoverer 5G ProSe UE. -User information ID of the discovered 5G ProSe UE: provides information about the discovered 5G ProSe UE. -User Information ID of 5G ProSe Inter-UE Relay: Provides information about 5G ProSe Inter-UE Relay. -Relay Service Code: Identifies the connectivity service provided by the 5G ProSe inter-UE relay to the 5G ProSe end UE. The following parameters are used for the 5G ProSe Inter-UE Relay Discovery Response message (Model B) between the 5G ProSe Inter-UE Relay and the discoverer 5G ProSe side UE, where the source layer 2 ID and the destination layer 2 ID are used to send and receive the message, and the user information ID and relay service code are included in the message: - Source Layer 2 ID: The discoverer 5G ProSe UE selects the source Layer 2 ID for relaying the discovery response message between 5G ProSe UEs. - Destination Layer 2 ID: set to the source Layer 2 ID of the received 5G ProSe Inter-UE Relay Discovery Request message. -User information ID of the discovered 5G ProSe UE: provides information about the discovered 5G ProSe UE. -User information ID of the discoverer 5G ProSe UE: provides information about the discoverer 5G ProSe UE. -Relay Service Code: identifies the connectivity service provided by the 5G ProSe inter-UE relay to the 5G ProSe end UE. It matches the relay service code from the corresponding discovery request message. NOTE: UE implementations need to ensure that when the UE self-selects a source Layer-2 ID, the self-selected source Layer-2 ID is different between 5G ProSe direct discovery (including 5G ProSe UE to network relay discovery and 5G ProSe inter-UE relay discovery) in clause 6.3.2 and 5G ProSe direct communication (including 5G ProSe UE to network relay communication and 5G ProSe inter-UE relay communication) in clauses 6.4, 6.5 and 6.7, and different from any other supplied destination Layer-2 ID as described in clause 5.1 and any other self-selected source Layer-2 ID used for simultaneous 5G ProSe direct discovery (including 5G ProSe UE to network relay discovery and 5G ProSe inter-UE relay discovery) with different discovery models. 5.8.5 Identifier for 5G ProSe Inter-UE Relay Communication with Integrated Discovery For the broadcast direct communication request message over the first-hop PC5 reference point, the source Layer 2 ID is selected by the source 5G ProSe end UE itself, and the destination Layer 2 ID is selected based on the configuration as described in clause 5.1. For the Broadcast Direct Communication Request message over the second-hop PC5 reference point, the source Layer 2 ID is selected by the 5G ProSe Inter-UE Relay itself, and the destination Layer 2 ID is selected based on the configuration as described in clause 5.1. The 5G ProSe inter-UE relay may send a unicast direct communication request message to the target 5G ProSe end UE by setting the destination layer 2 ID with the received unicast destination layer 2 ID of the target 5G ProSe end UE as specified in clause 6.4.3.7. The source layer 2 ID is selected by the 5G ProSe inter-UE relay itself. For unicast direct communication accept messages, the source layer 2 ID is selected by the target 5G ProSe UE or the 5G ProSe inter-UE relay itself. […] 6.3.2.4 5G ProSe Inter-UE Relay Discovery 6.3.2.4.1 Overview 5G ProSe inter-UE relay discovery is applicable to both 5G ProSe layer 3 and layer 2 inter-UE relay discovery for public safety use and commercial services. To perform 5G ProSe inter-UE relay discovery, the 5G ProSe-side UE and the 5G ProSe inter-UE relay are pre-configured or provisioned with relevant information as described in clause 5.1. The Relay Service Code (RSC) is used for 5G ProSe inter-UE relay discovery to indicate the connectivity service provided by the 5G ProSe inter-UE relay to the 5G ProSe end UE. The RSC is pre-configured or provisioned on the 5G ProSe inter-UE relay and the 5G ProSe end UE as defined in clause 5.1. The 5G ProSe inter-UE relay and the 5G ProSe end UE know whether the RSC is providing 5G ProSe Layer 2 or Layer 3 inter-UE relay service based on the inter-UE relay layer indicator as specified in clause 5.1. A 5G ProSe inter-UE relay that supports multiple RSCs advertises the RSCs using multiple discovery messages with one RSC per discovery message. 6.3.2.4.2 Procedure for 5G ProSe Inter-UE Relay Discovery using Model A Figure 6 .3.2.4.2-1 describes the procedure for 5G ProSe inter-UE discovery using Model A. [Figure 2 of 3GPP TS 23.304 V18.4.0 titled “5G ProSe Inter-UE Relay Discovery using Model A” 6.3.2.4.2-1 is reproduced as Figure 6 ] 1. The 5G ProSe Inter-UE Relay has discovered other UEs nearby (eg, via a previous 5G ProSe Inter-UE Relay discovery or 5G ProSe Inter-UE Relay communication procedure). The 5G ProSe Inter-UE Relay obtains the user information IDs of other UEs nearby according to the RSC. 2. The 5G ProSe Inter-UE Relay sends an Inter-UE Relay Discovery Notification message. The Inter-UE Relay Discovery Notification message contains the discovery message type, the user information ID of the 5G ProSe Inter-UE Relay, the RSC, and a list of user information IDs of 5G ProSe UEs that support RSC. The Inter-UE Relay Discovery Notification message is sent using the source Layer 2 ID and the destination Layer 2 ID, as described in clause 5.8.4. 5G ProSe inter-UE relay should only notify the user information IDs of other nearby UEs that did not previously contain a notification prohibition indication when discovered. NOTE: The 5G ProSe Inter-UE Relay notifies the user information ID of other neighboring UEs only if the PC5 signal strength of the other neighboring UEs measured by the 5G ProSe Inter-UE Relay is higher than the configured signal strength threshold as specified in TS 38.331

[16] . The 5G ProSe UE listens to the notification message from the 5G ProSe inter-UE relay. The 5G ProSe UE determines the destination Layer 2 ID for signaling reception as specified in clause 5.1. 6.3.2.4.3 Procedure for 5G ProSe Inter-UE Relay Discovery using Model B Figure 6 .3.2.4.3-1 describes the procedure for 5G ProSe inter-UE relay discovery using Model B. [3GPP TS 23.304 V18.4.0 titled "5G ProSe Inter-UE Relay Discovery using Model B" 6.3.2.4.3-1 is reproduced as Figure 7 ] 1. The discoverer 5G ProSe UE (UE-1) sends a 5G ProSe Inter-UE Relay Discovery Solicitation message. The 5G ProSe Inter-UE Relay Discovery Solicitation message contains the discovery message type, its own user information ID, RSC, and the user information ID of the discoverer 5G ProSe UE (UE-2), and is sent using the source Layer 2 ID and the destination Layer 2 ID, as described in clause 5.8.4. The 5G ProSe inter-UE relay determines the destination Layer 2 ID for signaling reception as specified in clause 5.1. The discoverer 5G ProSe-side UE may include a Notification Disable indication in the Inter-UE Relay Discovery Solicitation message. If the 5G ProSe Inter-UE Relay receives a Relay Discovery Solicitation message with a Notification Disable indication, it does not consider the 5G ProSe-side UE to be discovered during this procedure for inclusion in the 5G ProSe Inter-UE Relay Discovery using Model A, see clause 6.3.2.4.2, step 1. 2. If the RSC contained in the solicitation message matches any of the (pre-)configured RSCs of the 5G ProSe Inter-UE Relay, as specified in clause 5.1.5.1, the 5G ProSe Inter-UE Relay sends a 5G ProSe Inter-UE Relay Discovery Solicitation message. The 5G ProSe Inter-UE Relay Discovery Solicitation message contains the type of discovery message, the user information ID of the discoverer 5G ProSe end UE (UE-1), the user information ID of the inter-UE relay, the RSC, and the user information ID of the discoverer 5G ProSe end UE (UE-2), and is sent using the source Layer 2 ID and the destination Layer 2 ID, as described in clause 5.8.4. The 5G ProSe-side UE determines the destination Layer 2 ID for signaling reception as specified in clause 5.1. 3. If the RSC contained in the solicitation message matches any of the (pre-)configured RSCs of the discoverer 5G ProSe side UE (UE-2), as specified in clause 5.1.5.1, and the discoverer 5G ProSe side UE (UE-2) matches the user information ID of the discoverer 5G ProSe side UE (UE-2) contained in the solicitation message, then the discoverer 5G ProSe side UE (UE-2) responds to the 5G ProSe inter-UE relay with a 5G ProSe inter-UE relay discovery response message. The 5G ProSe inter-UE relay discovery response message contains the type of discovery message, the RSC, the user information ID of the discoverer 5G ProSe side UE (UE-1), and the user information ID of the discoverer 5G ProSe side UE (UE-2), and is sent using the source layer 2 ID and the destination layer 2 ID, as described in clause 5.8.4. If the discoverer 5G ProSe end UE (UE-2) receives multiple inter-UE relay discovery solicitation messages with the same RSC and user information ID of the discoverer 5G ProSe end UE (UE-2) from different 5G ProSe inter-UE relays, it may choose to respond to or not respond to the 5G ProSe inter-UE relay (for example, based on the PC5 signal strength of each received message). The discovered 5G ProSe UE may include a Notification Disable indication in the Inter-UE Relay Discovery Response message. If the 5G ProSe Inter-UE Relay receives a Relay Discovery Response message with a Notification Disable indication, it does not consider the 5G ProSe UE to be discovered during this procedure for inclusion in the 5G ProSe Inter-UE Relay Discovery using Model A, see clause 6.3.2.4.2, step 1. 4. The 5G ProSe Inter-UE Relay sends a 5G ProSe Inter-UE Relay Discovery Response message. The 5G ProSe Inter-UE Relay Discovery Response message contains the discovery message type, the user information ID of the inter-UE relay, the RSC, the user information ID of the discoverer 5G ProSe side UE (UE-1), and the user information ID of the discoverer 5G ProSe side UE (UE-2), and is sent using the source layer 2 ID and the destination layer 2 ID, as described in clause 5.8.4. 6.3.2.4.4 Candidate 5G ProSe Inter-UE Relay Discovery This procedure for candidate 5G ProSe inter-UE relay discovery supports negotiated relay reselection when the discoverer-side UE discovers a candidate 5G ProSe inter-UE relay, as described in clause 6.7.4. The procedure for 5G ProSe inter-UE relay discovery with Model B is used (see clause 6.3.2.4.3), with the following differences: -Step 1: The 5G ProSe Inter-UE Relay Discovery Request message includes the RSC and the user information ID of the candidate 5G ProSe Inter-UE Relay, but does not include the user information ID of the discovered 5G ProSe UE. If the 5G ProSe UE receives the Layer 2 ID of the candidate 5G ProSe Inter-UE Relay in the Link Modification Request message, it may set the Layer 2 ID of the candidate 5G ProSe Inter-UE Relay as the destination Layer 2 ID. Note: The user information ID of the candidate 5G ProSe inter-UE relay and the user information ID of the discovered 5G ProSe UE can be distinguished as different IEs in the message through the 5G ProSe inter-UE relay. - Skip steps 2 and 3 because there is no 5G ProSe end UE user information ID to be discovered, and the user information ID of the candidate 5G ProSe inter-UE relay in the received 5G ProSe inter-UE relay discovery request message matches the user information ID of the 5G ProSe inter-UE relay. - Step 4: If the 5G ProSe Inter-UE Relay matches the User Information ID of the candidate 5G ProSe Inter-UE Relay received in the 5G ProSe Inter-UE Relay Discovery Request, it sends a 5G ProSe Inter-UE Relay Discovery Response (and the RSC received in step 1) without including the User Information ID of the discovered 5G ProSe UE. […] 6.4.3 5G ProSe Direct Communication in Unicast Mode 6.4.3.1 Layer 2 link establishment over PC5 reference point To perform unicast mode of ProSe direct communication over PC5 reference point, the UE is configured with relevant information as described in clause 5.1.3. Figure 6 .4.3.1-1 shows the Layer 2 link establishment procedure for unicast mode of ProSe direct communication over the PC5 reference point. [3GPP TS 23.304 V18.4.0 entitled "Layer 2 Link Establishment Procedure" Figure 6 .4.3.1-1 Reproduced as Figure 8 ] 1. As specified in clause 5.8.2.4, the UE determines the destination Layer 2 ID for signaling reception for PC5 unicast link establishment. 2. The ProSe application layer in UE-1 provides application information for PC5 unicast communication. The application information includes ProSe service information and the UE's application layer ID. The application information may also include the target UE's application layer ID. The ProSe application layer in UE-1 may provide ProSe application requirements for this unicast communication.As specified in clause 5.6.1, UE-1 determines PC5 QoS parameters and PFI. If UE-1 decides to reuse the existing PC5 unicast link as specified in clause 5.3.4, the UE triggers the Layer 2 Link Modification procedure as specified in clause 6.4.3.4. 3. UE-1 sends a direct communication request message to initiate the unicast layer 2 link establishment procedure. The direct communication request message contains: - Source user information: the application layer ID of the originating UE (ie, the application layer ID of UE-1). If the ProSe application layer provides the target UE's application layer ID in step 2, the following information is included: - Target user information: the application layer ID of the target UE (ie, the application layer ID of UE-2). -ProSe service information: information about the ProSe identifier requesting Layer 2 link establishment. - Security information: information used to establish security. NOTE 1: Security information and the necessary protection of source user information and destination user information are defined in TS 33.503

[29] . As specified in clauses 5.8.2.1 and 5.8.2.4, determine the source layer 2 ID and destination layer 2 ID used to send the direct communication request message. The destination layer 2 ID can be a broadcast or unicast layer 2 ID. When using a unicast layer 2 ID, the target user information should be included in the direct communication request message. UE- 1 transmits a direct communication request message via PC 5 by broadcast or unicast using the source layer 2 ID and the destination layer 2 ID. The default PC5 DRX configuration may be used to transmit and receive this message (see TS 38.300

[12] ). 4. Establish security for UE-1 as follows: 4a. If the target user information is included in the direct communication request message, the target UE (ie, UE-2) responds by establishing security with UE-1. 4b. If the target user information is not included in the direct communication request message, the UE interested in using the announced ProSe service over the PC5 unicast link with UE-1 responds by establishing security with UE-1. NOTE 2: Signalling for security procedures is defined in TS 33.503

[29] . When security protection is enabled, UE-1 sends the following information to the target UE: - If using IP communication, then: -IP Address Configuration: For IP communication, this link requires IP address configuration, and IP address configuration indicates one of the following values: - "DHCPv4 server", if only IPv4 address allocation mechanism is supported by the initiating UE, i.e. acting as a DHCPv4 server; or - "IPv6 router", if only the IPv6 address allocation mechanism is supported by the initiating UE, i.e. acting as an IPv6 router; or - "DHCPv4 server and IPv6 router", if both IPv4 and IPv6 address allocation mechanisms are supported by the initiating UE; or - "Address allocation not supported" if neither IPv4 nor IPv6 address allocation mechanisms are supported by the initiating UE. - Link-local IPv6 address: If UE-1 does not support the IPv6 IP address allocation mechanism, i.e., the IP address configuration indicates "address allocation not supported", a link-local IPv6 address is formed locally based on RFC 4862

[17] . - QoS information: Information about PC5 QoS flows. For each PC5 QoS flow, PFI and corresponding PC5 QoS parameters (ie, PQI and conditionally other parameters such as MFBR / GFBR, etc.) and optionally associated ProSe identifier. -Optional PC5 QoS rules. As specified in clauses 5.8.2.1 and 5.8.2.4, the source Layer 2 ID for the security establishment procedure is determined. The destination Layer 2 ID is set to the source Layer 2 ID of the received direct communication request message. After receiving the Security Setup Procedure message, UE-1 obtains the Layer 2 ID of the peer UE for future communications for signaling and data traffic for this unicast link. 5. The target UE, which has successfully established security with UE-1, sends a direct communication acceptance message to UE-1: 5a. (Layer 2 Link Establishment Towards UE) If the target user information is included in the Direct Communication Request message, the target UE (ie, UE-2) responds with a Direct Communication Accept message if the application layer ID for UE-2 matches. 5b. (Layer 2 Link Establishment for ProSe Services) If the direct communication request message does not contain target user information, the UE interested in using the notified ProSe service ( Figure 6 .UE-2 and UE-4 in 4.3.1-1) respond to the request by sending a direct communication accept message. The direct communication acceptance message includes: -Source user information: the application layer ID of the UE that sends the direct communication accept message. - QoS information: Information about PC5 QoS flows. For each PC5 QoS flow, PFI and corresponding PC5 QoS parameters requested by UE-1 (ie, PQI and conditionally other parameters such as MFBR / GFBR, etc.) and optionally an associated ProSe identifier. -Optional PC5 QoS rules. - If using IP communication, then: -IP Address Configuration: For IP communication, this link requires IP address configuration, and IP address configuration indicates one of the following values: - "DHCPv4 server", if only IPv4 address allocation mechanism is supported by the target UE, i.e. act as a DHCPv4 server; or - "IPv6 router", if only IPv6 address allocation mechanisms are supported by the target UE, i.e. acting as an IPv6 router; or - "DHCPv4 server and IPv6 router", if both IPv4 and IPv6 address allocation mechanisms are supported by the target UE; or - "Address allocation not supported" if neither IPv4 nor IPv6 address allocation mechanisms are supported by the target UE. - Link-local IPv6 address: If the target UE does not support the IPv6 IP address allocation mechanism, i.e., the IP address configuration indicates "address allocation not supported" and UE-1 contains a link-local IPv6 address for security establishment in step 4, a link-local IPv6 address is formed locally based on RFC4862

[17] . The target UE shall contain a non-conflicting link-local IPv6 address. If two UEs (ie, the initiating UE and the target UE) are selected to use link-local IPv6 addresses, then the two UEs shall disable dual address detection as defined in RFC 4862

[17] . NOTE 3: When the initiating UE or the target UE indicates support for IPv6 routing, the corresponding address configuration procedure shall be implemented after the Layer 2 link is established and the link-local IPv6 address shall be ignored. The ProSe layer of the UE that establishes a PC5 unicast link passes the PC5 link identifier and PC5 unicast link-related information allocated for the unicast link down to the AS layer. The PC5 unicast link-related information includes Layer 2 ID information (i.e., source Layer 2 ID and destination Layer 2 ID). This enables the AS layer to maintain the PC5 link identifier and PC5 unicast link-related information. Two UEs may negotiate the PC5 DRX configuration in the AS layer, and PC5 DRX parameter values ​​may be configured for each pair of source and destination Layer 2 IDs in the AS layer. 6. ProSe data is transmitted via the established unicast link as follows: The PC5 link identifier and PFI are provided to the AS layer together with the ProSe data. Additionally, layer 2 ID information (ie, source layer 2 ID and destination layer 2 ID) is optionally provided to the AS layer. NOTE 4: It is up to the UE implementation to provide the Layer 2 ID information to the AS layer. UE-1 sends ProSe data using a source Layer 2 ID (ie, the Layer 2 ID of UE-1 for this unicast link) and a destination Layer 2 ID (ie, the Layer 2 ID of the peer UE for this unicast link). NOTE 5: The PC5 unicast link is bidirectional, so UE-1's peer UE can send ProSe data to UE-1 through the unicast link with UE-1. […] 6.4.3.2 Link Identifier Update for Unicast Links Figure 6 4.3.2-1 shows the link identifier update procedure for unicast links. When privacy requirements are configured for ProSe identifiers associated with unicast links, the identifiers (e.g., application layer ID, source layer 2 ID, and IP address / prefix) used for unicast mode of 5G ProSe communication over the PC5 reference point should change over time, as specified in clauses 5.8.2.1 and 5.8.2.4. For other reasons, such as application layer requirements, the UE may decide to change the identifier. This procedure is used to update and exchange new identifiers between the source and peer UEs for unicast links before they are used, thereby preventing service interruption. This procedure is performed over security-protected unicast links when privacy requirements exist as indicated above. If a UE has multiple unicast links using the same application layer ID or layer 2 ID, the UE needs to perform a link identifier update procedure over each of the unicast links. [3GPP TS23.304 V18.4.0 entitled "Link Identifier Update Procedure" Figure 6 .4.3.2-1 Reproduced as Figure 9] 0. UE-1 and UE-2 have a unicast link established as described in clause 6.4.3.1. 1. UE-1 decides to change its identifier, for example due to an application layer ID change or when a timer expires. UE-1 generates its new layer 2 ID using the old identifier and sends a Link Identifier Update Request message to UE-2. The Link Identifier Update Request message contains the new identifier to be used (including the new Layer 2 ID, security information, optionally the new Application Layer ID, and, if IP communication is used, optionally the new IP address / prefix). If security is configured for the unicast link, the new identifier should be encrypted to protect privacy. After sending the Link Identifier Update Request message, if UE-1 has data to send, UE-1 continues to send data traffic to UE-2 using the old identifier until UE-1 sends a Link Identifier Update Confirm message to UE-2. NOTE 1: The timer runs for each source layer 2 ID. NOTE 2: When one of the two UEs acts as an IPv6 router (as described in clause 5.5.1.1) and the IP address / prefix also needs to be changed, the corresponding address configuration procedure shall be carried out after the link identifier update procedure. 2. After receiving the Link Identifier Update Request message, UE-2 changes its identifier. UE-2 responds with a Link Identifier Update Response message, which contains the new identifier to be used (including the new Layer 2 ID, security information, optionally the new Application Layer ID, and optionally the new IP address / prefix if IP communication is used). If security is configured for the unicast link, the new identifier should be encrypted to protect privacy. The Link Identifier Update Response message is sent using the old identifier. UE-2 continues to receive traffic from UE-1 using the old Layer 2 ID until UE-2 receives traffic from UE-1 using the new Layer 2 ID. After sending the Link Identifier Update Response message, if UE-2 has data to send, UE-2 continues to send data traffic to UE-1 using the old identifier until UE-2 receives a Link Identifier Update Confirm message from UE-1. 3. After receiving the Link Identifier Update Response message, UE-1 responds with a Link Identifier Update Confirm message. The Link Identifier Update Confirm message includes the new identifier received from UE-2 in the Link Identifier Update Response message. The Link Identifier Update Confirm message is sent using the old identifier. UE-1 continues to receive services from UE-2 using the old Layer 2 ID until UE-1 receives services from UE-2 using the new Layer 2 ID. 4. The ProSe layer of UE-1 passes the PC5 link identifier for the unicast link and the updated Layer 2 ID (i.e., the new Layer 2 ID for the source UE-1 and the new Layer 2 ID for the destination UE-2) down to the AS layer. This enables the AS layer to update the provided Layer 2 ID for the unicast link. For this unicast link, UE-1 starts using its new identifier and UE-2's new identifier. 5. After receiving the Link Identifier Update Confirm message, the ProSe layer of UE-2 passes the PC5 link identifier and the updated Layer 2 ID for the unicast link (i.e., the new Layer 2 ID for the source UE-2 and the new Layer 2 ID for the destination UE-1) down to the AS layer. This enables the AS layer to update the provided Layer 2 ID for the unicast link. UE-2 starts using its new identifier and UE-1's new identifier for this unicast link. NOTE 3: The security information in the above message also needs to be updated simultaneously with the Layer 2 ID. This is defined in TS 33.503

[29] . […] 6.4.3.4 Layer 2 Link Modification for Unicast Links Figure 6 .4.3.4-1 shows the Layer 2 link modification procedure for unicast links. This procedure is used to: -Add new PC5 QoS flow in existing PC5 unicast link. - This covers the case for adding a new PC5 QoS flow to an existing ProSe service as well as the case for adding a new PC5 QoS flow to a new ProSe service. - Modify an existing PC5 QoS flow in an existing PC5 unicast link. - This covers the case for modifying PC5 QoS parameters for an existing PC5 QoS flow. - This also covers the case for removing an associated ProSe service from an existing PC5 QoS flow and the case for associating a new ProSe service with an existing PC5 QoS flow. - Remove existing PC5 QoS flows in existing PC5 unicast links. [3GPP TS 23.304 V18.4.0 entitled "Layer 2 Link Modification Procedure" Figure 6 .4.3.4-1 is reproduced as Figure 10 ] 0. UE-1 and UE-2 have a unicast link established as described in clause 6.4.3.1. 1. The ProSe application layer in UE-1 provides application information for PC5 unicast communication. The application information includes ProSe service information and the application layer ID of the initiating UE. The application information may also include the application layer ID of the target UE. If UE-1 decides to reuse the existing PC5 unicast link as specified in clause 5.3.4 and therefore decides to modify the unicast link established with UE-2, UE-1 sends a link modification request to UE-2. The link modification request message contains: a) To add a new PC5 QoS flow to an existing PC5 unicast link: - QoS information: Information about the PC5 QoS flow to be added. For each PC5 QoS flow, PFI, corresponding PC5 QoS parameters (ie, PQI and conditionally other parameters such as MFBR / GFBR), and optionally an associated ProSe identifier. -Optional PC5 QoS rules. b) To modify a PC5 QoS flow in an existing PC5 unicast link: - QoS information: Information about the PC5 QoS flow to be modified. For each PC5 QoS flow, PFI, corresponding PC5 QoS parameters (ie, PQI and conditionally other parameters such as MFBR / GFBR), and optionally an associated ProSe identifier. -Optional PC5 QoS rules. c) To remove the PC5 QoS flow from an existing PC5 unicast link: -PFI. 2. UE-2 responds with a Link Modification Accept message. The link modification acceptance message contains: - For case a) and case b) described in step 1: -QoS information: Information about the PC5 QoS flow requested by UE-1. QoS flow, PFI, corresponding PC5 QoS parameters (ie PQI and conditionally other parameters such as MFBR / GFBR) and optionally associated ProSe identifier. -Optional PC5 QoS rules. The ProSe layer of each UE provides information about the unicast link modification to the AS layer, which enables the AS layer to update the context related to the modified unicast link. […] 6.4.3.7.1 Common part of Layer 2 link management over the PC5 reference point for 5G ProSe inter-UE relay For 5G ProSe communication via 5G ProSe inter-UE relay as described in clauses 6.7.1 and 6.7.2: -The direct communication request message on the first hop PC5 reference point contains: -User information ID of the source 5G ProSe UE: the identifier of the source 5G ProSe UE requesting the relay operation. - User information ID of 5G ProSe inter-UE relay: The identifier of the inter-UE relay provided to the source 5G ProSe end UE during the 5G ProSe inter-UE relay discovery procedure. - User information ID of target 5G ProSe UE: the identifier of the target 5G ProSe UE provided to the source 5G ProSe UE during the inter-UE relay discovery procedure. - (Optional) Destination Layer 2 ID of the target 5G ProSe end UE: the unicast destination Layer 2 ID of the target 5G ProSe end UE determined by the source 5G ProSe end UE, as specified in clause 5.8.2.4. -ProSe service information: information about the ProSe identifier requesting Layer 2 link establishment. -RSC: Connectivity service requested by the source 5G ProSe UE and provided by the 5G ProSe inter-UE relay. - Security information: information used to establish security for first-hop PC5 link establishment. NOTE 1 Security information is defined by SA WG3. The direct communication request message on the second hop PC5 reference point contains: -User information ID of the source 5G ProSe UE. -User information ID of the target 5G ProSe UE. -User information ID relayed between 5G ProSe UEs. -ProSe service information: information about the ProSe identifier. -RSC: Connectivity service requested by the source 5G ProSe UE and provided by the 5G ProSe inter-UE relay. - Security information: information used to establish security for establishing a second-hop PC5 link. NOTE 2 Security information is defined by SA WG3. The direct communication acceptance message on the second hop PC5 reference point contains: -User information ID of the target 5G ProSe UE. The direct communication acceptance message on the first hop PC5 reference point contains: -User information ID of the target 5G ProSe UE. -User information ID relayed between 5G ProSe UEs. The link modification request message on the first-hop PC5 reference point contains: - User information ID of target 5G ProSe UE: the identifier of the target 5G ProSe UE provided to the source 5G ProSe UE during the inter-UE relay discovery procedure. - (Optional) Destination Layer 2 ID of the target 5G ProSe end UE: the unicast destination Layer 2 ID of the target 5G ProSe end UE determined by the source 5G ProSe end UE, as specified in clause 5.8.2.4. The link modification request message on the second-hop PC5 reference point contains: -User information ID of the source 5G ProSe UE. -User information ID of the target 5G ProSe UE. The link modification accept message on the second-hop PC5 reference point contains: -User information ID of the target 5G ProSe UE. The Link Modification Accept message on the first-hop PC5 reference point contains: -User information ID of the target 5G ProSe UE. 6.4.3.7.2 Layer 2 Link Management over PC5 Reference Point for 5G ProSe Layer 2 Inter-UE Relay For 5G ProSe communication via 5G ProSe layer 2 inter-UE relay as described in clause 6.7.2, the description in clause 6.4.3.7.1 applies. The message contents over the PC5 reference point for unicast mode 5G ProSe direct communication described in clauses 6.4.3.1 to 6.4.3.5 are the same for end-to-end connections between peer 5G ProSe end UEs. Editor's note: Whether LIU between peer-to-peer UEs has the same message content as direct PC5 LIU messages is for further study. […] 6.4.3.7.4 Layer 2 Link Management over PC5 Reference Point for 5G ProSe Inter-UE Relay Communication with Integrated Discovery This clause is for 5G ProSe inter-UE relay communication integrated with the discovery procedure, as described in clause 6.7.3. The direct communication request message on the first hop PC5 reference point contains: -User information ID of the source 5G ProSe UE. - (Optional) User Information ID of the target 5G ProSe UE: the identifier of the target 5G ProSe UE (if provided by the ProSe application layer). - (Optional) Destination Layer 2 ID of the target 5G ProSe end UE: the unicast destination Layer 2 ID of the target 5G ProSe end UE determined by the source 5G ProSe end UE, as specified in clause 5.8.2.4. -ProSe service information: information about the ProSe identifier requesting Layer 2 link establishment. -RSC: Connectivity service requested by the source 5G ProSe UE and provided by the 5G ProSe inter-UE relay. -Relay_indication: indicates whether the direct communication request message can be forwarded by the 5G ProSe inter-UE relay. - Security information: information used to establish security for first-hop PC5 link establishment. NOTE 1 Security information is defined by SA WG3. The direct communication request message on the second hop PC5 reference point contains: -User information ID of the source 5G ProSe UE. -User information ID relayed between 5G ProSe UEs. -(Optional) User information ID of the target 5G ProSe UE. -ProSe service information: information about the ProSe identifier. -RSC: Connectivity service requested by the source 5G ProSe UE and provided by the 5G ProSe inter-UE relay. - Security information: information used to establish security for establishing a second-hop PC5 link. NOTE 2 Security information is defined by SA WG3. The direct communication acceptance message on the second hop PC5 reference point contains: -User information ID of the target 5G ProSe UE. The direct communication acceptance message on the first hop PC5 reference point contains: -User information ID of the target 5G ProSe UE. -User information ID relayed between 5G ProSe UEs. For 5G ProSe communication via 5G ProSe layer 3 inter-UE relay, additional explanations are as follows: -In the security procedure of the second-hop PC5 reference point, the 5G ProSe layer 3 inter-UE relay provides the IP address configuration or link-local IPv6 address to the target 5G ProSe end UE. - The Direct Communication Accept message over the second-hop PC5 reference point additionally includes the IP address configuration or link-local IPv6 address (if IP communication is used) and the Ethernet MAC address of the target 5G ProSe UE (if Ethernet communication is used). QoS information is not included in the security procedures or Direct Communication Accept message over the second-hop PC5 reference point. -In the security procedure of the first-hop PC5 reference point, the source 5G ProSe end UE provides the IP address configuration, link-local IPv6 address and QoS information of end-to-end QoS to the 5G ProSe layer 3 inter-UE relay. -5G ProSe Layer 3 Inter-UE Relay uses Layer 2 Link Modification to provide QoS information of the second-hop QoS to the target 5G ProSe end UE, as described in clause 6.4.3.4. - Taking into account the second-hop QoS received from the target 5G ProSe side UE, the 5G ProSe layer 3 inter-UE relay determines the QoS information of the first-hop QoS, and the direct communication accept message on the first-hop PC5 reference point additionally contains the IP address configuration or link-local IPv6 address, the QoS information of the first-hop QoS, and may include the IP address of the target 5G ProSe side UE (if IP communication is used) or the Ethernet MAC address of the target 5G ProSe side UE (if Ethernet communication is used). For 5G ProSe communication via 5G ProSe layer 2 inter-UE relay, the message contents over the PC5 reference point for unicast mode 5G ProSe direct communication described in clauses 6.4.3.1 to 6.4.3.5 are the same for end-to-end connections between peer 5G ProSe end UEs. […] 6.7.2 5G ProSe Communication via 5G ProSe Layer 2 Inter-UE Relay This app is applicable to 5G ProSe layer 2 inter-UE relay. [3GPP TS 23.304 V18.4.0 entitled "5G ProSe communication via 5G ProSe layer 2 inter-UE relay" Figure 6 .7.2-1 is reproduced as Figure 11 ] This procedure has been preceded by service authorization and provisioning for the 5G ProSe layer 2 inter-UE relay and the 5G ProSe end UE, as described in clause 6.2. 1. Model A or Model B 5G ProSe inter-UE relay discovery as described in clause 6.3.2.4 is performed, and the source 5G ProSe end UE selects an appropriate 5G ProSe layer 2 inter-UE relay for communicating with the target 5G ProSe end UE. 2. The source 5G ProSe UE decides whether to use the existing PC5 link with the 5G ProSe Inter-UE Relay to obtain the required service. If the existing PC5 link is used, the Layer 2 link modification procedure as specified in clause 6.4.3.7 is used towards the 5G ProSe Inter-UE Relay. Otherwise, the Layer 2 link establishment procedure is used towards the 5G ProSe Inter-UE Relay. This procedure is towards the selected 5G ProSe Inter-UE Relay and for Layer 2 link establishment, security establishment is performed before initiating step 3. 3. The 5G ProSe Layer 2 Inter-UE Relay decides whether to use the existing PC5 link between the 5G ProSe Inter-UE Relay and the target 5G ProSe end UE to obtain the required service, and initiates the Layer 2 link establishment procedure or Layer 2 link modification procedure as specified in clause 6.4.3.7 with the target 5G ProSe end UE. This procedure is performed using a unicast Layer 2 ID towards the target 5G ProSe UE. After step 3 is completed, the 5G ProSe layer 2 inter-UE relay sends a direct communication accept message or a link modification accept message to the source 5G ProSe end UE. 4. The source 5G ProSe UE establishes an end-to-end connection for unicast mode communication with the target 5G ProSe UE, as described in clause 6.4.3.7. Data and end-to-end PC5-S signaling are transferred between the source 5G ProSe UE and the target 5G ProSe UE via the 5G ProSe layer 2 inter-UE relay. The 5G ProSe layer 2 inter-UE relay forwards all data traffic and end-to-end PC5-S signaling between the source 5G ProSe UE and the target 5G ProSe UE as specified in TS 38.300

[12] . 6.7.3 5G ProSe Inter-UE Relay Communication with Integrated Discovery 6.7.3.1 Overview Supports 5G ProSe communication via 5G ProSe inter-UE relay with integrated discovery. For 5G ProSe inter-UE relay communication integrated with discovery, when a UE allows direct communication requests to other UEs involving inter-UE relay, the UE indicates this by including relay_indication in the broadcast direct communication request message. When the inter-UE relay receives a direct communication request containing relay_indication, it decides whether to forward the message based on, for example, the relay service code (if present), application ID, operator policy for each relay service code, signal strength, and local policy. 6.7.3.2 Procedures for communication via Layer 3 Inter-UE Relay [3GPP TS 23.304 V18.4.0 entitled “5G ProSe Inter-UE Relay Communication with Integrated Discovery via Layer 3 Inter-UE Relay” Figure 6 .7.3.2-1 is reproduced as Figure 12 ] 0.5G ProSe end UEs are authorized and equipped with parameters to use services provided by 5G ProSe inter-UE relays. 5G ProSe inter-UE relays are authorized and equipped with parameters to provide services of relaying traffic among 5G ProSe end UEs. 1. The source 5G ProSe UE (ie, UE-1) wants to establish unicast communication with the target 5G ProSe UE (ie, UE-2) and broadcasts a direct communication request. The parameters included in the direct communication request message are described in clause 6.4.3.7. The relay_indication in the direct communication request is used to indicate whether the 5G ProSe inter-UE relay can forward the direct communication request message. It is also used to limit the number of hops of the 5G ProSe inter-UE relay by removing the relay_indication in the direct communication request message from the 5G ProSe inter-UE relay. The source layer 2ID and destination layer 2ID for the direct communication request message are defined in clause 5.8.5. The source 5G ProSe UE obtains application information and optional ProSe application requirements from the ProSe application layer, and determines end-to-end QoS parameters as described in clause 5.6.3.1. NOTE 1: The data type of relay_indication can be determined in phase 3. 2. Upon receiving a direct communication request with relay_indication from UE-1, the 5G ProSe inter-UE relays (i.e., Relay-1 and Relay-2) may decide to participate in the procedure and broadcast a direct communication request message in their vicinity without relay_indication. The parameters included in the direct communication request message are described in clause 6.4.3.7. The source layer 2ID and destination layer 2ID for the direct communication request message are defined in clause 5.8.5. 3. When UE-2 receives a direct communication request from one or more 5G ProSe inter-UE relays, UE-2 selects a 5G ProSe inter-UE relay to which UE-2 will respond. UE-2 may select a 5G ProSe inter-UE relay based on, for example, signal strength, local policy, and operator policy for each relay service code (if any). 4. If required, security establishment occurs between UE-2 and the selected 5G ProSe Inter-UE Relay (here Relay-1). If an existing PC5 link can be reused, the Link Modify Request and Link Modify Accept messages are used. NOTE 2: Conflicts between link modification requests and direct communication requests may be determined in Phase 3. 5. UE-2 replies with a direct communication accept message to relay-1. The parameters included in the direct communication accept message are described in clause 6.4.3.7. 6. For IP services, allocate an IPv6 prefix or IPv4 address to the target 5G ProSe Layer 3 UE, as defined in clause 5.5.1.4. 7. If required, security establishment occurs between UE-1 and Relay-1. 8. For 5G ProSe inter-UE relay communication with integrated discovery, after receiving the QoS information of end-to-end QoS from UE-1, Relay-1 uses the Link Modification Request message to provide QoS information of second-hop QoS to UE-2. 9. For 5G ProSe inter-UE relay communication with integrated discovery, UE-2 responds with a Link Modification Accept message. 10. Relay-1 responds to UE-1 with a Direct Communication Accept message. The parameters included in the Direct Communication Accept message are described in clause 6.4.3.7. 11. For IP services, an IPv6 prefix or IPv4 address is allocated to the source 5G ProSe layer 3 UE as defined in clause 5.5.1.4. 12. For IP communication, the 5G ProSe layer 3 inter-UE relay may store the association between the user information ID and the IP address of the target 5G ProSe layer 3 end UE in its DNS entry, and the 5G ProSe layer 3 inter-UE relay may act as a DNS server for other UEs. If the IP address of the target 5G ProSe layer 3 end UE is not received in step 10, the source 5G ProSe layer 3 end UE may send a DNS query to the 5G ProSe layer 3 inter-UE relay after step 11 to request the IP address of the target 5G ProSe layer 3 end UE, and the 5G ProSe layer 3 inter-UE relay may transmit the IP address of the target 5G ProSe layer 3 end UE back to the source 5G ProSe layer 3 end UE. For Ethernet communication, the 5G ProSe Layer 3 inter-UE relay acts as an Ethernet switch by maintaining the association between the PC5 link and the Ethernet MAC address received from the 5G ProSe Layer 3 end UE. For unstructured traffic communications, for each pair of source and target 5G ProSe layer 3 UEs, the 5G ProSe layer 3 inter-UE relay maintains a 1:1 mapping between the PC5 link and the source 5G ProSe layer 3 UE and between the PC5 link and the target 5G ProSe layer 3 UE. The source 5G ProSe layer 3 end UE communicates with the target 5G ProSe layer 3 end UE via a 5G ProSe layer 3 inter-UE relay. 6.7.3.3 Procedures for communication via Layer 2 Inter-UE Relay [3GPP TS 23.304 V18.4.0 entitled “5G ProSe Inter-UE Relay Communication with Integrated Discovery via Layer 2 Inter-UE Relay” Figure 6 .7.3.3-1 is reproduced as Figure 13 ] 0-5. Figure 6 .7.3.2-1 steps 0 to 5 are the same. 6. Its Figure 6 Same as step 7 of .7.3.2-1. 7. Its Figure 6 Same as step 10 of 7.3.2-1. The parameters contained in the above messages are described in clause 6.4.3.7.4. 8. For 5G ProSe inter-UE relay communication via Layer 2 inter-UE relay, UE-1 establishes an end-to-end connection for unicast mode communication with UE-2. Editor's Note: Any additional updates to procedures via Layer 2 Inter-UE Relay, such as those based on RAN decisions, will be included here.

[0047] 3GPP TS 38.300 introduces U2U relay as follows: 16.12.2.2 L2 Inter-UE Relay The protocol stack for user plane and control plane of L2 U2U relay architecture is Figure 16 .12.2.2-1 and Figure 16 As shown in .12.2.2-2. The SRAP sublayer is located above the RLC sublayer for CP and UP at both PC5 interfaces. Sidelink SDAP, PDCP, and RRC terminate between the two L2 U2U remote UEs (i.e., end-to-end), while SRAP, RLC, MAC, and PHY terminate at each hop of the PC5 link. [Figure 3GPP TS 38.300 V18.0.0 entitled "User plane protocol stack for L2 inter-UE relay" 16.12.2.2-1 is reproduced as Figure 14 ] [Figure 3GPP TS 38.300 V18.0.0, titled "Control plane protocol stack for L2 inter-UE relay" 16.12.2.2-2 is reproduced as Figure 15 ] For L2 inter-UE relay, the SRAP sublayer at the L2 U2U remote UE: - The SRAP sublayer at the L2 U2U remote UE performs bearer mapping between end-to-end PC5 radio bearers (SL-SRB or SL-DRB) of the L2 U2U remote UE at each hop of the PC5 relay RLC channel between the L2 U2U remote UE and the L2 U2U relay UE. - For traffic transferred from L2 U2U Remote UE to L2 U2U Relay UE, different end-to-end PC5 radio bearers (SL- SRBs or SL-DRBs) may be multiplexed to the same PC5 relay RLC channel between the L2U2U remote UE and the L2 U2U relay UE. - For traffic received at an L2 U2U remote UE, the same PC5 relay RLC channel from one L2 U2U relay UE may be demultiplexed to different end-to-end PC5 radio bearers (SL-SRB or SL-DRB) of the same peer L2 U2U remote UE and / or different peer L2 U2U remote UEs. - The SRAP sublayer at the L2 U2U remote UE supports identification of the peer L2 U2U remote UE and itself. The L2 U2U relay UE assigns local IDs to two L2 U2U remote UEs for identification. One of the two local IDs identifies the L2 U2U remote UE, and the other identifies the peer L2 U2U remote UE. The L2 U2U relay UE delivers the local ID of the peer L2 U2U remote UE and the local ID of the L2 U2U remote UE, along with the corresponding L2 ID of the peer L2 U2U remote UE, to the L2 U2U remote UE. The identification information of the end-to-end PC5 radio bearer and the two local IDs are included in the SRAP header, allowing the peer L2 U2U remote UE to associate received packets for a specific PDCP entity with the correct end-to-end PC5 radio bearer of the L2 U2U remote UE. For L2 inter-UE relay, the SRAP sublayer at the L2 U2U relay UE: - The SRAP sublayer at the L2 U2U Relay UE determines the egress PC5 Relay RLC channel based on a mapping of end-to-end PC5 radio bearers and egress PC5 Relay RLC channels for a specific pair between the L2 U2U Remote UE and the peer L2 U2U Remote UE. -For ingress traffic received from one / multiple L2 U2U remote UEs at an L2 U2U relay UE, different end-to-end PC5 radio bearers (SL-SRB or SL-DRB) of the same L2 U2U remote UE and / or the same / different end-to-end PC5 radio bearers (SL-SRB or SL-DRB) of the L2 U2U remote UE may be multiplexed into the same egress PC5 relay RLC channel between the L2 U2U relay UE and the peer L2 U2U remote UE. […] 16.12.7 Control Plane Procedures for L2 U2U Relay The L2 U2U remote UE needs to establish an end-to-end SL-SRB / DRB with the peer L2 U2U remote UE before user plane data transmission. Figure 16 The following high-level connection establishment procedures in .12.7-1 apply to L2 U2U relay UE and L2 U2U remote UE: [Figure 3GPP TS 38.300 V18.0.0 entitled "Procedure for L2 U2U Remote UE Connection Establishment" 16.12.7-1 is reproduced as Figure 16 ] 1. The L2 U2U remote UE, the L2 U2U relay UE and the peer L2 U2U remote UE perform a discovery procedure or an integrated discovery procedure. 2a. The L2 U2U remote UE establishes / modifies a PC5-RRC connection with the selected L2 U2U relay UE (ie as specified in TS 23.304

[48] ). 2b. The L2 U2U Relay UE establishes / modifies a PC5-RRC connection with the peer L2 U2U Remote UE (ie as specified in TS 23.304

[48] ). 3. The L2 U2U relay UE allocates two local IDs, which are delivered to each L2 U2U remote UE via an RRCReconfigurationSidelink message: one local ID for identifying the L2 U2U remote UE, and the other local ID for identifying the peer L2 U2U remote UE. When the local IDs are delivered, the L2 ID of the peer L2 U2U remote UE is also delivered to the U2U remote UE for association between the local ID and the L2 ID of the peer U2U remote UE. 4. An L2 U2U remote UE establishes an end-to-end PC5-RRC connection with a peer L2 U2U remote UE via an L2 U2U relay UE. For end-to-end connection establishment, fixed indices (i.e., 0 / 1 / 2 / 3) are defined for end-to-end SL-SRB 0 / 1 / 2 / 3, respectively, and a specific PC5 relay RLC channel configuration is used on each hop. Sidelink UE capabilities are exchanged between L2 U2U remote UEs via PC5-RRC (e.g., SL-SRB3) messages. 5. The L2 U2U remote UE sends all QoS attribute sets for the end-to-end QoS flow to the L2 U2U relay UE via PC5-RRC. 6. The L2 U2U relay UE performs QoS splitting only for PDBs. Note: It is up to the L2 U2U relay UE implementation to decide how to split the PDB. 7. The L2 U2U relay UE sends the split QoS value (ie, PDB) to the L2 U2U remote UE via PC5-RRC message. 8. The L2 U2U Remote UE or the L2 U2U Remote UE's serving gNB derives the PDCP and SDAP configuration for the end-to-end SL-DRB and provides the peer L2 U2U Remote UE with a portion of the reception-related configuration using an End-to-End RRCReconfigurationSidelink message. The end-to-end bearer ID for the SL-SRB and SL-DRB is used as input for L2 U2U Relay encryption and decryption at PDCP. 9a. The L2 U2U remote UE or the serving gNB of the L2 U2U remote UE derives the first-hop configuration for the SL-DRB (e.g., PC5 relay RLC channel configuration) and provides the configuration related to reception on the first hop (i.e., Rx by the relay UE) to the L2 U2U relay UE using a per-hop RRCReconfigurationSidelink message. 9b. The L2 U2U relay UE or the L2 U2U relay UE's serving gNB derives the second-hop configuration (e.g., PC5 relay RLC channel configuration) for each SL-DRB and provides the configuration related to receiving packets on the second hop (i.e., RX by the peer remote UE) to the peer L2 U2U remote UE using a per-hop RRCReconfigurationSidelink message. 10. The L2 U2U remote UE and the peer L2 U2U remote UE transmit or receive data via the L2 U2U relay UE.

[0048] 3GPP TS 38.331 introduces U2U relay as follows: 5.8.9.1 Sidelink RRC Reconfiguration 5.8.9.1.1 Overview [3GPP TS 38.331 V18.0.0 entitled "Sidelink RRC reconfiguration, success" Figure 5 .8.9.1.1-1 is reproduced as Figure 17 ] [3GPP TS 38.331 V18.0.0 entitled "Sidelink RRC reconfiguration, failure" Figure 5 .8.9.1.1-2 is reproduced as Figure 18 ] The purpose of this procedure is to modify the PC5-RRC connection, such as establishing / modifying / releasing sidelink DRB or additional sidelink RLC bearer or PC5 relay RLC channel, adding / modifying / releasing sidelink carrier, (re)configuring NR sidelink measurement and reporting, (re)configuring sidelink CSI reference signal resources, (re)configuring CSI reporting delay bound, (re)configuring sidelink DRX, (re)configuring delay bound for SL inter-UE coordinated reporting and indicating SFN-DFN offset. In the following cases, the UE may initiate the sidelink RRC reconfiguration procedure and perform the operations in clause 5.8.9.1.2 on the corresponding PC5-RRC connection: - in case of L2 U2U relay operation, release of sidelink DRBs associated with a peer UE or L2 U2U relay UE and peer L2U2U remote UE, as specified in clause 5.8.9.1a.1; - in case of L2 U2U relay operation, establishment of sidelink DRBs associated with a peer UE or L2 U2U relay UE and a peer L2U2U remote UE, as specified in clause 5.8.9.1a.2; - modification of parameters contained in the SLRB-Config for the sidelink DRB associated with the peer UE, as specified in clause 5.8.9.1a.2; - Release of additional sidelink RLC bearers associated with the peer UE, as specified in clause 5.8.9.1a.5; - establishment of additional sidelink RLC bearers associated with the peer UE, as specified in clause 5.8.9.1a.6; -SL-RLC for inclusion in additional sidelink RLC bearers associated with a peer UE- Modification of parameters in BearerConfig, as specified in clause 5.8.9.1a.6; - Release of the PC5 relay RLC channel for L2 U2N / U2U relay UE and remote UE as specified in clause 5.8.9.7.1; - Establishment of PC5 relay RLC channels for L2 U2N / U2U relay UE and remote UE as specified in clause 5.8.9.7.2; - modification of the parameters contained in SL-RLC-ChannelConfigPC5 for the PC5 relay RLC channel for L2 U2N / U2U relay UEs and remote UEs, as specified in clause 5.8.9.7.2; - Release of a sidelink carrier associated with a peer UE, as specified in clause 5.8.9.1b.1; - the addition of a sidelink carrier associated with a peer UE, as specified in clause 5.8.9.1b.2; - modification of the sidelink carrier associated with the peer UE, as specified in clause 5.8.9.1b.2; - (Re)configure the peer UE to perform NR sidelink measurements and reporting. - (Re)configuration of sidelink CSI reference signal resources and CSI reporting delay bounds; - (re)configure the peer UE to perform sidelink DRX; - (Re)configuration of delay bounds for coordinated reporting between SL UEs; - (Re)configuration of the Local UE ID of an L2 U2U Remote UE by an L2 U2U Relay UE. - A response to a request for SFN-DFN offset from an L2 U2N remote UE in a RemoteUEInformationSidelink message; - Change in the value of SFN-DFN offset at the L2 U2N relay UE. NOTE: It is up to the L2 U2N Relay UE implementation to determine when the value of the SFN-DFN offset has changed to such an extent that an update needs to be sent to the L2 U2N Remote UE. In RRC_CONNECTED, the UE applies the NR sidelink communication parameters provided in RRCReconfiguration (if present). In RRC_IDLE or RRC_INACTIVE, the UE applies the NR sidelink communication parameters provided in system information (if present). For other cases, the UE applies the NR sidelink communication parameters provided in SidelinkPreconfigNR (if present). When the UE performs a state transition between the above three cases, after obtaining the new configuration, the UE applies the NR sidelink communication parameters provided in the new state. Before obtaining the new configuration, the UE continues to apply the NR sidelink communication parameters provided in the old state. 5.8.9.1.2 Actions Related to the Transmission of the RRCReconfigurationSidelink Message The UE shall set the content of the RRCReconfigurationSidelink message as follows: 1> For each side link DRB to be released, according to clause 5.8.9.1a.1.1, due to sl- ConfigDedicatedNR, SIB12, SidelinkPreconfigNR, or upper-layer configuration: 2> Set the entry contained in slrb-ConfigToReleaseList corresponding to the sidelink DRB; 1> For each side link DRB to be established or modified, according to clause 5.8.9.1a.2.1, due to receiving sl- ConfigDedicatedNR, SIB12 or SidelinkPreconfigNR: 2> If the sidelink DRB is a per-hop sidelink DRB (i.e., the UE does not act as an L2 U2U remote UE): 3> If a sidelink DRB is to be established: 4> Assign a new logical channel identifier for the logical channel to be associated with the sidelink DRB and set sl-MAC-LogicalChannelConfigPC5 in SLRB-Config to include the new logical channel identifier; 3>According to the received sl-RadioBearerConfig and sl-RLC- BearerConfig, sets the SLRB-Config contained in slrb-ConfigToAddModList; 2> Otherwise, if the sidelink DRB is an end-to-end sidelink DRB (i.e., the UE acts as an L2 U2U remote UE and the peer L2 U2U remote UE is configured with end-to-end SDAP and PDCP, or a QoS flow to end-to-end DRB mapping is provided to an L2 relay UE): 3> If the UE is in RRC_CONNECTED: 4> Set the SLRB-Config contained in slrb-ConfigToAddModList according to the received sl-RadioBearerConfig in sl-ConfigDedicatedNR; 3> Otherwise, if the UE is in RRC_IDLE / RRC_INACTIVE: 4> According to the sl-RadioBearerConfig in SIB12, set the SLRB-Config in ConfigToAddModList, which is derived from the end-to-end QoS attribute set; 3> If the UE is out of coverage: 4> According to the sl-RadioBearerConfig in SidelinkPreconfigNR, set the SLRB-Config contained in slrb-ConfigToAddModList, which is derived through the end-to-end QoS attribute set; 1> For each additional sidelink RLC bearer to be released, due to sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR or upper layer configuration according to clause 5.8.9.1a.5.1: 2> Set the entry contained in sl-RLC-BearerToReleaseList corresponding to the additional sidelink RLC bearer; 1> for each additional sidelink RLC bearer to be established or modified, according to clause 5.8.9.1a.6.1, due to reception of sl-ConfigDedicatedNR, SIB12, or SidelinkPreconfigNR: 2> If additional sidelink RLC bearers are to be established: 3> Assign a new logical channel identifier for the logical channel to be associated with the sidelink DRB and set sl-MAC-LogicalChannelConfigPC5 in SL-RLC-BearerConfig to include the new logical channel identifier; 2>According to the received sl-RadioBearerConfig and the sl- RLC-BearerConfig, set the SL-RLC- BearerConfig; 1> setting the entry contained in the sl-CarrierToReleaseList corresponding to the sidelink carrier in which the MAC entity indicates that the maximum number of consecutive HARQ DTXs for a particular destination has been reached; 1> Consider at least the carriers mapped to the sidelink QoS flow configured by upper layers, the carriers configured in sl-ConfigDedicatedNR, SIB12 or SidelinkPreconfigNR and the carriers supported by both UEs, and set the entries contained in sl-CarrierToAddModList corresponding to the sidelink carriers; 1>Set sl-MeasConfig as follows: 2> If the frequency used for NR sidelink communication is contained in sl-FreqInfoToAddModList / sl-FreqInfoToAddModListExt in sl-ConfigDedicatedNR in RRCReconfiguration message or in sl-ConfigCommonNR in SIB12: 3> If the UE is in RRC_CONNECTED: 4> Set sl- according to the NR sidelink measurement configuration information stored for this destination MeasConfig; 3> If the UE is in RRC_IDLE or RRC_INACTIVE: 4> Set sl- according to the stored NR side link measurement configuration received from SIB12 MeasConfig; 2> Otherwise: 3>Set sl- according to sl-MeasPreconfig in SidelinkPreconfigNR MeasConfig; 1>Set sl-LatencyBoundIUC-Report; 1>Start timer T400 for the destination; 1>Set sl-CSI-RS-Config; 1>Set sl-LatencyBoundCSI-Report; 1>Set sl-ResetConfig; NOTE 1: Whether / how to set the parameters included in sl-LatencyBoundIUC-Report, sl-CSI-RS-Config, sl-LatencyBoundCSI-Report and sl-ResetConfig depends on the UE implementation. 1> Set sl-DRX-ConfigUC-PC5 as follows: 2> If the frequency used for NR sidelink communication is contained in sl-FreqInfoToAddModList / sl-FreqInfoToAddModListExt in sl-ConfigDedicatedNR in RRCReconfiguration message or in sl-ConfigCommonNR in SIB12: 3> If the UE is in RRC_CONNECTED and if the sl-ScheduledConfig is contained in the sl-ConfigDedicatedNR within the RRCReconfiguration: 4> Set sl-DRX- according to the NR sidelink DRX configuration information stored for this destination ConfigUC-PC5; NOTE 2: If the UE is in RRC_IDLE or in RRC_INACTIVE or out of coverage or in RRC_CONNECTED and sl-UE-SelectedConfig is included in sl-ConfigDedicatedNR in RRCReconfiguration, sl-DRX-ConfigUC-PC5 is set depending on the UE implementation. 1> For each PC5 relay RLC channel to be released due to the configuration of sl-ConfigDedicatedNR: 2> Set the SL-RLC-ChannelID corresponding to the PC5 relay RLC channel in sl-RLC-ChannelToReleaseListPC5; 1> For each PC5 relay RLC channel to be established or modified due to receipt of sl-ConfigDedicatedNR: 2> To establish a PC5 relay RLC channel: 3> Assign a new logical channel identifier for the logical channel to be associated with the PC5 relay RLC channel and set sl-MAC-LogicalChannelConfigPC5 in SL-RLC-ChannelConfigPC5 to include the new logical channel identifier; 2> Set the SL-RLC-ChannelConfigPC5 contained in sl-RLC-ChannelToAddModListPC5 according to the received SL-RLC-ChannelConfig corresponding to the PC5 relay RLC channel, including setting sl-RLC-ChannelID-PC5 to the sl-RLC- The same value of ChannelID; 1> If the UE acts as an L2 U2N relay UE: 2> If the destination UE is an L2 U2N remote UE that requested SFN-DFN offset in a previous RemoteUEInformationSidelink message: 3> If the SFN-DFN offset has changed since the previous transmission of the RRCReconfigurationSidelink message, or no previous transmission of the RRCReconfigurationSidelink message has occurred since the RemoteUEInformationSidelink message was received: 4> Set sl-SFN- according to the relationship between the SFN timeline and DFN timeline of PCell DFN-Offset; 1> If the UE acts as a L2 U2U relay UE and if the procedure is initiated to configure the local ID as a connected L2 U2U remote UE: 2> If a local ID pair is to be allocated or modified for end-to-end PC5 connection, and if a PC5-RRC connection with the L2U2U remote UE and a PC5-RRC connection with the peer L2 U2U remote UE are successfully established: Include the entry in sl-LocalID-PairToAddModList and set the fields as follows: 4> If necessary, set sl-RemoteUE-LocalIdentity to contain the new local UE ID, and set sl- RemoteUE-L2Identity is set to include the source L2 ID of the L2 U2U remote UE in the SL- SRAP-ConfigPC5; 4> set sl-PeerRemoteUE-LocalIdentity to contain the new local UE ID and sl-PeerRemoteUE-L2Identity to contain the destination L2 ID of the peer L2 U2U remote UE contained in SL-SRAP-ConfigPC5, as needed, based on the association between user information and L2 IDs as specified in TS 23.304

[65] ; 2> Otherwise, if the local ID pair is to be released for use in an end-to-end PC5 connection: 3> Include the entry in sl-LocalID-PairToReleaseList, where SL- The value of DestinationIdentity is set to the destination L2 ID of the peer L2 U2U remote UE; 1> if the UE acts as an L2 U2U remote UE (i.e., Tx UE), and if the procedure is initiated to configure the first-hop PC5 relay RLC channel of the end-to-end sidelink DRB as a connected L2 U2N relay UE (i.e., Rx UE) based on the configuration in SIB12 or SidelinkPreconfigNR; or 1> If the UE acts as an L2 U2U relay UE (i.e., Tx UE) and is in RRC_IDLE or in RRC_INACTIVE or OoC, and if the initiator configures the second-hop PC5 relay RLC channel as a connected L2 U2N remote UE (i.e., Rx UE) based on the configuration in SIB12 or SidelinkPreconfigNR: 2> To establish a PC5 relay RLC channel: 3> Allocate a new RLC channel ID and replace the sl-RLC- ChannelID-PC5 is set to contain the new RLC channel ID; 3> Assign a new logical channel identifier for the logical channel to be associated with the PC5 relay RLC channel and set sl-MAC-LogicalChannelConfigPC5 in SL-RLC-ChannelConfigPC5 to include the new logical channel identifier; 3> If the UE is in RRC_IDLE or RRC_INACTIVE: 4>SL-RLC derived from per-hop QoS based on end-to-end SLRB according to SIB12 BearerConfig to set the SL- RLC-ChannelConfigPC5; 3> Otherwise, if the UE is out of coverage: 4> Set the SL-RLC-ChannelConfigPC5 contained in sl-RLC-ChannelToAddModListPC5 according to the SL-RLC-BearerConfig derived based on the per-hop QoS of the SLRB according to SidelinkPreconfigNR; NOTE 3: If the UE is in RRC_IDLE or in RRC_INACTIVE or out of coverage, how to merge the split per-flow QoS on the first / second hop into the per-SLRB level QoS derived for RLC channel configuration depends on the UE implementation. The UE shall submit an RRCReconfigurationSidelink message to lower layers for transmission. 5.8.9.1.3 UE Reception of RRCReconfigurationSidelink The UE shall perform the following actions after receiving RRCReconfigurationSidelink: 1> If RRCReconfigurationSidelink includes sl-ResetConfig: 2> Perform the sidelink reset configuration procedure as specified in 5.8.9.1.10; 1> If RRCReconfigurationSidelink contains slrb-ConfigToReleaseList: 2> For each entry value contained in slrb-ConfigToReleaseList that is part of the current UE side link configuration; 3> Perform the sidelink DRB release procedure according to clause 5.8.9.1a.1; 1> If RRCReconfigurationSidelink contains slrb-ConfigToAddModList: 2> For each slrb-PC5-ConfigIndex value included in slrb-ConfigToAddModList that is not part of the current UE side link configuration: 3> If sl-MappedQoS-FlowsToAddList is included: 4> Apply the SL-PQFI contained in sl-MappedQoS-FlowsToAddList; 3> Perform the sidelink DRB addition procedure according to clause 5.8.9.1a.2; 2> For each slrb-PC5-ConfigIndex value contained in slrb-ConfigToAddModList that is part of the current UE side link configuration: 3> If sl-MappedQoS-FlowsToAddList is included: 4> Add the SL-PQFI contained in sl-MappedQoS-FlowsToAddList to the corresponding sidelink DRB; 3> If sl-MappedQoS-FlowsToReleaseList is included: 4> Remove the data contained in sl-MappedQoS- SL-PQFI in FlowsToReleaseList; 3> If the sidelink DRB release conditions described in clause 5.8.9.1a.1.1 are met: 4> Perform the sidelink DRB release procedure according to clause 5.8.9.1a.1.2; 3> Otherwise, if the sidelink DRB modification conditions described in clause 5.8.9.1a.2.1 are met: 4> Perform the sidelink DRB modification procedure according to clause 5.8.9.1a.2.2; 1> If RRCReconfigurationSidelink contains sl-RLC-BearerToReleaseList: 2> for each entry value contained in the sl-RLC-BearerToReleaseList that is part of the current UE-side link configuration; 3> Perform additional sidelink RLC bearer release procedures according to clause 5.8.9.1a.5; 1> If RRCReconfigurationSidelink contains sl-RLC-BearerToAddModList: 2> For each SL-RLC-BearerConfigIndex value contained in sl-RLC-BearerToAddModList that is not part of the current UE-side link configuration: 3> Perform the additional sidelink RLC bearer addition procedure according to clause 5.8.9.1a.6; 2> For each SL-RLC-BearerConfigIndex value included in the sl-RLC-BearerToAddModList that is part of the current UE-side link configuration: 3> Perform the additional sidelink RLC bearer modification procedure according to clause 5.8.9.1a.6; 1> If RRCReconfigurationSidelink contains sl-CarrierToReleaseList: 2> For each entry value contained in the sl-CarrierToReleaseList that is part of the current UE side link configuration; 3> Perform the sidelink carrier release procedure according to clause 5.8.9.1b.1; 1> If RRCReconfigurationSidelink contains sl-CarrierToAddModList: 2> For each sl-Carrier-Id value included in the sl-CarrierToAddModList that is not part of the current UE-side link configuration: 3> Perform the sidelink carrier addition procedure according to clause 5.8.9.1b.2; 2> For each sl-Carrier-Id value included in the sl-CarrierToAddModList as part of the current UE side link configuration: 3> Perform carrier modification procedures according to clause 5.8.9.1b.2; 1> If the RRCReconfigurationSidelink message contains sl-MeasConfig: 2> Perform the sidelink measurement configuration procedure as specified in 5.8.10; 1> If the RRCReconfigurationSidelink message contains sl-CSI-RS-Config: 2> Application side link CSI-RS configuration; 1> If the RRCReconfigurationSidelink message includes sl-LatencyBoundCSI-Report: 2> Apply the configured sidelink CSI reporting delay bound; 1> If RRCReconfigurationSidelink contains sl-RLC-ChannelToReleaseListPC5: 2> for each SL-RLC-ChannelID value contained in sl-RLC-ChannelToReleaseListPC5 as part of the current UE-side link configuration; 3> According to clause 5.8.9.7.1, execute the PC5 relay RLC channel release procedure; 1> If RRCReconfigurationSidelink contains sl-RLC-ChannelToAddModListPC5: 2> For each sl-RLC-ChannelID-PC5 value contained in sl-RLC-ChannelToAddModListPC5 that is not part of the current UE-side link configuration: 3> Perform the PC5 relay RLC channel addition procedure according to clause 5.8.9.7.2; 2> For each sl-RLC-ChannelID-PC5 value contained in sl-RLC-ChannelToAddModListPC5 as part of the current UE side link configuration: 3> Execute the PC5 relay RLC channel modification procedure according to clause 5.8.9.7.2; 1> If the RRCReconfigurationSidelink message contains sl-DRX-ConfigUC-PC5; and 1> If the UE accepts sl-DRX-ConfigUC-PC5: 2> Configure the lower layers to follow the sl- DRX-ConfigUC-PC5 to perform sidelink DRX operation; 1> If the RRCReconfigurationSidelink message includes sl-LatencyBoundIUC-Report: 2> Apply the configured side link IUC reporting delay bound; 1> If the RRCReconfigurationSidelink message contains sl-LocalID-PairToReleaseList or sl-LocalID-PairToAddModList: 2>Configure the SRAP entity to perform NR sidelink L2 U2U relay operations accordingly, for end-to-end PC5 connectivity to peer L2 U2U remote UEs as defined in TS 38.351

[65] ; 1> If the RRCReconfigurationSidelink message contains sl-MappingToAddModListPC5 or sl-MappingToReleaseListPC5: 2> configure the lower layers to perform NR sidelink L2U2U relay operation according to the mapping between the end-to-end sidelink bearers of the L2 U2U remote UE and the egress PC5 relay RLC channels as defined in TS 38.351

[65] ; 1> If the UE is unable to comply with the (partial) configuration contained in RRCReconfigurationSidelink (i.e., sidelink RRC reconfiguration failure): 2> Continue to use the configuration used before receiving the RRCReconfigurationSidelink message; 2>Set the content of the RRCReconfigurationFailureSidelink message; 3> Submit the RRCReconfigurationFailureSidelink message to the lower layer for transmission; 1> If the RRCReconfigurationSidelink message contains sl-SFN-DFN-Offset: 2> If sl-SFN-DFN-Offset is set to setup: 3> Apply the configured SFN-DFN time offset; 2> If sl-SFN-DFN-Offset is set to release: 3> Release the received sl-SFN-DFN-Offset; 1> Otherwise: 2>Set the content of the RRCReconfigurationCompleteSidelink message; 3> If the UE rejects the sidelink DRX configuration sl-DRX-ConfigUC- received from the peer UE PC5: 4> Include sl-DRX-ConfigReject in In the RRCReconfigurationCompleteSidelink message; 4> not considering the sidelink DRX to be applied to the corresponding sidelink unicast communication; 3> Submit the RRCReconfigurationCompleteSidelink message to the lower layer for transmission; NOTE 1: When the same logical channel is configured with a different RLC mode by another UE, the UE treats the situation as a sidelink RRC reconfiguration failure. NOTE 2: It is up to the UE implementation to decide whether to indicate a rejection of the received sidelink DRX configuration to the peer UE. […] 5.8.9.1a Sidelink Radio Bearer Management 5.8.9.1a.1 Sidelink DRB Release 5.8.9.1a.1.1 Sidelink DRB Release Conditions For NR sidelink communications, a sidelink DRB release is initiated in the following situations: 1> For multicast, broadcast, and unicast, if the slrb-Uu-ConfigIndex (if present) of the sidelink DRB is included in the sl-RadioBearerToReleaseList in the sl-ConfigDedicatedNR; or 1> For multicast and broadcast, if no sidelink QoS flow with data indicated by upper layers is mapped to a sidelink DRB for transmission, the sidelink QoS flow is (re)configured by receiving SIB12 or SidelinkPreconfigNR; or 1> for multicast, broadcast, and unicast, if the SL-RLC-BearerConfigIndex (if present) of the associated RLC entity for the sidelink DRB (i.e., including the additional sidelink RLC bearers, if applicable) is contained in the sl-RLC-BearerToReleaseList / sl-RLC-BearerToReleaseListSizeExt in the sl-ConfigDedicatedNR; or 1> for unicast, if no sidelink QoS flow with data indicated by upper layers is mapped to the sidelink DRB for transmission, the sidelink QoS flow is (re)configured by receiving SIB12 or SidelinkPreconfigNR, and if no sidelink QoS flow mapped to the sidelink DRB has data, the sidelink QoS flow is (re)configured by receiving RRCReconfigurationSidelink; or 1> for unicast, if the SLRB-PC5-ConfigIndex (if present) of the sidelink DRB is included in slrb-ConfigToReleaseList in RRCReconfigurationSidelink or if sl-ResetConfig is included in RRCReconfigurationSidelink; or 1> for unicast, when the corresponding PC5-RRC connection is released due to detection of sidelink RLF according to clause 5.8.9.3; or 1> For unicast, when the corresponding PC5-RRC connection is released due to a request from upper layers according to clause 5.8.9.5. 5.8.9.1a.1.2 Sidelink DRB Release Operation For each sidelink DRB for which the sidelink DRB release conditions are met as in clause 5.8.9.1a.1.1, an NR sidelink capable UE configured by upper layers to perform NR sidelink communication shall: 1> for multicast and broadcast; or 1> For unicast, if the sidelink DRB release is triggered after receiving the RRCReconfigurationSidelink message; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB release is triggered due to the configuration received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR or indicated by upper layers: 2> Release the PDCP entity associated with the sidelink DRB for NR sidelink communication; 2> If the SDAP entity for NR sidelink communication associated with this sidelink DRB is configured as: 3> Indicate the release of the side link DRB to the SDAP entity associated with this side link DRB (TS 37.324

[24] , clause 5.3.3); 2> Release the SDAP entity (if any) that does not have an associated sidelink DRB as specified in TS 37.324

[24] clause 5.1.2 for NR sidelink communication; 1> for multicast and broadcast; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB release is triggered due to the configuration received in sl-ConfigDedicatedNR: 2> For sl-RLC- received as part of the current UE side link configuration Each sl-RLC- BearerConfigIndex: 3> Release the RLC entity and corresponding logical channel used for NR sidelink communication, where the NR sidelink communication is associated with sl-RLC-BearerConfigIndex. 1> For unicast, if the sidelink DRB release is triggered by receiving an RRCReconfigurationSidelink message; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB release is triggered due to the configuration received in SIB12, SidelinkPreconfigNR or indicated by upper layers: 2> Release the RLC entity and corresponding logical channel associated with the sidelink DRB for NR sidelink communication; 2> Perform the sidelink UE information procedure for unicast in clause 5.8.3 when necessary. 1> If a sidelink radio link failure is detected for a particular destination: 2> Release the PDCP entity, RLC entity and logical channel used for the sidelink DRB of a specific destination. Editor's Note: Further research is needed to release SL DRBs on E2E and hop configuration for U2U relay. 5.8.9.1a.2 Sidelink DRB Addition / Modification 5.8.9.1a.2.1 Sidelink DRB Addition / Modification Conditions For NR sidelink communication, sidelink DRB addition is initiated only in the following cases: 1> If any sidelink QoS flow is configured by sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR (re)configure and map to a sidelink DRB that is not established; or 1> If any sidelink QoS flow is (re)configured by RRCReconfigurationSidelink and will be mapped to an unestablished sidelink DRB; For NR sidelink communications, sidelink DRB modification is initiated only in the following cases: 1> If, for an established sidelink DRB, any of the sidelink DRB-related parameters are changed via sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR, or RRCReconfigurationSidelink; 5.8.9.1a.2.2 Sidelink DRB Add / Modify Operation For a sidelink DRB for which the sidelink DRB addition conditions are met as in clause 5.8.9.1a.2.1, an NR sidelink capable UE configured by upper layers to perform NR sidelink communication shall: 1> for multicast and broadcast; or 1> For unicast, if the sidelink DRB addition is triggered due to the reception of an RRCReconfigurationSidelink message; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB addition is triggered due to the configuration received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR or indicated by upper layers: 2> If there is no SDAP entity for NR sidelink communication associated with the destination and broadcast type of the sidelink DRB: 3> establish the SDAP entity for NR sidelink communication as specified in TS 37.324

[24] clause 5.1.1; 2> (Re)configure the SDAP entity according to the sl-SDAP-ConfigPC5 received in RRCReconfigurationSidelink or the sl-SDAP-Config received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR associated with the sidelink DRB; 2> establish a PDCP entity for NR sidelink communication and configure it according to the sl-PDCP-ConfigPC5 received in RRCReconfigurationSidelink or the sl-PDCP-Config received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR associated with the sidelink DRB; 2> For each hop sidelink DRB (i.e., UE does not act as L2 U2U remote UE): 3> Establish an RLC entity for NR sidelink communication and configure the NR sidelink communication according to the sl-RLC-ConfigPC5 received in RRCReconfigurationSidelink or the sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR received in association with the sidelink DRB. RLC-Config configures the RLC entity; 3> If this procedure is due to receiving an RRCReconfigurationSidelink message: 4> configure the MAC entity with the logical channel according to the sl-MAC-LogicalChannelConfigPC5 received in RRCReconfigurationSidelink associated with the sidelink DRB and perform the Sidelink UE Information procedure in clause 5.8.3 for unicast if required; 3> Otherwise, if this procedure is due to receipt of an RRCReconfigurationCompleteSidelink message: 4> Configure the MAC entity with the logical channel associated with the sidelink DRB according to the sl-MAC-LogicalChannelConfig received in sl-ConfigDedicatedNR, SIB12, and SidelinkPreconfigNR; 3> Otherwise (i.e., for multicast / broadcast): 4> Configure the MAC entity with the logical channel associated with the sidelink DRB according to the sl-MAC-LogicalChannelConfig received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR, and allocate a new LCID to this logical channel. 2> For end-to-end side link DRB (i.e., UE acts as L2 U2U remote UE): 3> If the UE is in RRC_CONNECTED: 4> Associate this end-to-end side link DRB with the PC5 RLC channel indicated by sl-EgressRLC-ChannelPC5 contained in sl-ConfigDedicatedNR received from RRCReconfiguration; 3> Otherwise, if the UE is in RRC IDLE or RRC INACTIVE: 4> Based on the configuration in SIB12, associate this end-to-end side link DRB with the PC5 RLC channel derived through the per-SLRB QoS attribute set of this end-to-end side link DRB; 3> Otherwise, if the UE is out of coverage: 4> Based on the configuration in SidelinkPreconfigNR, associate this end-to-end side link DRB with the PC5 RLC channel derived through the per-SLRB QoS attribute set of this end-to-end side link DRB; NOTE 1: When the sidelink DRB addition is due to the configuration of RRCReconfigurationSidelink, it is up to the UE implementation to select the sidelink DRB configuration that transmits the parameters of the sidelink DRB as needed from the received sl-ConfigDedicatedNR (if in RRC_CONNECTED), SIB12 (if in RRC_IDLE / INACTIVE), SidelinkPreconfigNR (if out of coverage) with the same RLC mode as configured in RRCReconfigurationSidelink. For a sidelink DRB for which the sidelink DRB modification conditions in clause 5.8.9.1a.2.1 are met, a UE capable of NR sidelink communication that is configured by upper layers to perform NR sidelink communication shall: 1> for multicast and broadcast; or 1> For unicast, if the sidelink DRB modification is triggered by receiving an RRCReconfigurationSidelink message; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB modification is triggered due to the configuration received in sl-ConfigDedicatedNR, SIB12 or SidelinkPreconfigNR: 2>According to the sl-SDAP-ConfigPC5 received in RRCReconfigurationSidelink or the sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR (if included) received in SDAP-Config reconfigures the SDAP entity of the side link DRB; 2> According to the sl-PDCP-ConfigPC5 received in RRCReconfigurationSidelink or the sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR (if included) received PDCP-Config reconfigures the PDCP entity of the sidelink DRB; 2> According to the sl-RLC-ConfigPC5 received in RRCReconfigurationSidelink or the sl-RLC- Config reconfigures the RLC entity of the sidelink DRB; 2>According to the sl-MAC- received in RRCReconfigurationSidelink LogicalChannelConfigPC5 or in sl-ConfigDedicatedNR, SIB12, The sl-MAC-LogicalChannelConfig received in SidelinkPreconfigNR (if included) reconfigures the logical channel of the sidelink DRB. […] 5.8.9.7.1 PC5 Relay RLC Channel Release The UE shall: 1> If the PC5 relay RLC channel release is triggered after receiving the RRCReconfigurationSidelink message; or 1> After receiving the RRCReconfigurationCompleteSidelink message, if due to the sl- The configuration received in ConfigDedicatedNR triggers the release of the PC5 relay RLC channel; or 1> For unicast in L2 U2U relay operation, if there is no end-to-end side link DRB associated with this RLC channel: 2> For sl-RLC- received in sl-ConfigDedicatedNR within RRCReconfiguration For each SL-RLC-ChannelID in ChannelToReleaseList or for each SL-RLC- ChannelID, or for the RLC channel to be released: 3> Release the RLC entity and the corresponding logical channel associated with SL-RLC-ChannelID; 1> If the PC5 relay RLC channel release is triggered by upper layers as specified in 5.8.9.5 for a specific destination, or by upper layers as specified in 5.8.9.10.4 for a specific destination corresponding to the received sl-DestinationIdentityRemoteUE, or is triggered due to sidelink RLF as specified in 5.8.9.3: 2> Release the RLC entity and the corresponding logical channel associated with the SL-RLC-ChannelID of the specific destination; […] 5.8.9.11 Sidelink UE Information 5.8.9.11.1 Overview [3GPP TS 38.331 V18.0.0 entitled "Sidelink UE Information Procedure" Figure 5 .8.9.11.1-1 is reproduced as Figure 19 ] The purpose of this procedure is to transmit UE information in the sidelink. The L2 U2U remote UE informs its connected L2 U2U relay UE of its end-to-end QoS information in the UEInformationRequestSidelink message, and the L2 U2U relay UE delivers the first-hop split QoS information to the remote UE in the UEInformationResponseSidelink message. Editor's Note: Whether this message configuration is optimal can be discussed during maintenance. Whether it covers the case where the relay UE updates the QoS split can be discussed during maintenance. 5.8.9.11.2 Actions related to the transmission of UEInformationRequestSidelink by the UE For the initial information transfer (e.g. for QoS splitting) or after any of the information in the UEInformationRequestSidelink has changed, the UE shall set the content of the UEInformationRequestSidelink message as follows: 1> If the UE acts as an L2 U2U remote UE: 2> If configured by upper layers, set sl-E2E-QoS-ConnectionListPC5 to the end-to-end QoS attribute set containing the sidelink QoS flows of the peer L2 U2U remote UE, and for each entry: 3> If configured by upper layers, sl-DestinationIdentityRemoteUE is set to contain the associated destination identity for the peer L2 U2U remote UE; 2> Submit the UEInformationRequestSidelink message to the lower layer for transmission; 5.8.9.11.3 Actions related to the reception of UEInformationRequestSidelink by the UE The UE shall perform the following actions after receiving the UEInformationRequestSidelink: 1> If the UE acts as an L2 U2U relay UE: 2> If UEInformationRequestSidelink contains sl-E2E-QoS-ConnectionListPC5: 3> Perform QoS splitting based on the sl-QoS-InfoList for each QoS flow to determine the split PDB value for each PC5 hop; 3> Set the content of the UEInformationResponseSidelink message as follows: 4> Set sl-SplitQoS-InfoListPC5 to contain the split PDB values ​​for each QoS flow on the first PC5 hop between the L2 U2U relay UE and the L2 U2U remote UE; 4> If configured by upper layers, sl-DestinationIdentityRemoteUE is set to contain the associated destination identity for the peer L2 U2U remote UE; 3> Submit the UEInformationResponseSidelink message to the lower layer for transmission; Note: How to split the PDB depends on the relay UE implementation. […] -RRCReconfiguration The RRCReconfiguration message is a command to modify the RRC connection. It can convey information for measurement configuration, mobility control, radio resource configuration (including RB, MAC primary configuration and physical channel configuration), and AS security configuration. Signaling radio bearer: SRB1 or SRB3 RLC-SAP:AM Logical channel: DCCH Direction: Network to UE RRCReconfiguration message … -SL-L2RelayUE-Config The IE SL-L2RelayUE-Config is used to configure L2 U2N relay operation-related configurations used by an L2 U2N relay UE, or L2 U2U relay operation-related configurations used by an L2 U2U relay UE. SL-L2RelayUE-Config information element -SL-L2RemoteUE-Config The IE SL-L2RemoteUE-Config is used to configure configurations related to L2 U2N relay operations used by L2 U2N remote UEs, or configurations related to L2 U2U relay operations used by L2 U2U remote UEs. SL-L2RemoteUE-Config information element […] -SL-SRAP-ConfigU2U The IE SL-SRAP-ConfigU2U is used to set the configurable SRAP parameters used by the L2 U2U Relay UE and the L2 U2U Remote UE as specified in TS 38.351

[66] . SL-SRAP-ConfigU2U information element […] -SidelinkUEInformationNR The SidelinkUEinformationNR message is used to indicate the NR sidelink UE information to the network. Signaling Radio Bearer: SRB1 RLC-SAP:AM Logical channel: DCCH Direction: UE to network SidelinkUEInformationNR message Editor's Note: Whether each SLRB QoS is reported in a list of E2E connections or all in one big list can be further checked during maintenance. Editor's note: Whether to distinguish between U2U discovery and U2N discovery can be checked during maintenance. […] […] -RRCReconfigurationSidelink The RRCReconfigurationSidelink message is a command for AS configuration of the PC5 RRC connection. It applies only to unicast NR sidelink communications. Signaling radio bearer: SL-SRB3 RLC-SAP:AM Logical channel: SCCH Direction: UE to UE RRCReconfigurationSidelink message Editor's Note: The field sl-AbsoluteFrequencyPointA together with sl-OffsetToCarrier is sufficient for the Rx UE to understand which carrier is to be added / modified / released from the Rx UE perspective. […] -UEInformationRequestSidelink The UEInformationRequestSidelink message is used to transmit UE information in the sidelink, such as end-to-end QoS information for L2U2U relay operation. Signaling radio bearer: SL-SRB3 RLC-SAP:AM Logical channel: SCCH Direction: L2 U2U remote UE to L2 U2U relay UE UEInformationRequestSidelink message -UEInformationResponseSidelink The UEInformationResponseSidelink message is used to deliver UE information in the sidelink, such as split QoS information for L2U2U relay operation. Signaling radio bearer: SL-SRB3 RLC-SAP:AM Logical channel: SCCH Direction: L2 U2U relay UE to L2 U2U remote UE UEInformationResponseSidelink message […] -SL-PreconfigurationNR The IE SL-PreconfigurationNR contains the sidelink preconfigured parameters for NR sidelink communication. The requirement codes or conditions specified for the subfields in SL-PreconfigurationNR do not apply. SL-PreconfigurationNR information element

[0049] 3GPP Email Discussion [Post125]

[402] [Relay]38.331Rel-18 Relay CR [4] describes the following: 5.8.9.1.2 Actions Related to the Transmission of the RRCReconfigurationSidelink Message The UE shall set the content of the RRCReconfigurationSidelink message as follows: 1> For each sidelink DRB to be released, according to clause 5.8.9.1a.1.1, due to sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR or upper layer configuration: 2> Set the entry contained in slrb-ConfigToReleaseList corresponding to the sidelink DRB; 1> For each sidelink DRB to be established or modified, according to clause 5.8.9.1a.2.1, due to the reception of sl-ConfigDedicatedNR, SIB12 or SidelinkPreconfigNR: 2> If the sidelink DRB is a per-hop sidelink DRB (i.e., the UE performs non-relay NR sidelink communication with a peer UE): 3> If a sidelink DRB is to be established: 4> Assign a new logical channel identifier for the logical channel to be associated with the sidelink DRB and set sl-MAC-LogicalChannelConfigPC5 in SLRB-Config to include the new logical channel identifier; 3> Set the SLRB-Config contained in slrb-ConfigToAddModList according to the received sl-RadioBearerConfig and sl-RLC-BearerConfig corresponding to the sidelink DRB; 2> Otherwise, if the sidelink DRB is an end-to-end sidelink DRB (i.e., the UE acts as an L2 U2U remote UE and the peer L2 U2U remote UE is configured with end-to-end SDAP and PDCP, or a QoS flow to end-to-end DRB mapping is provided to an L2 relay UE): 3> If the UE is in RRC_CONNECTED: 4> Set the SLRB-Config contained in slrb-ConfigToAddModList according to the received sl-RadioBearerConfig in sl-ConfigDedicatedNR; 3> Otherwise, if the UE is in RRC_IDLE / RRC_INACTIVE: 4> According to the sl-RadioBearerConfig in SIB12, set the SLRB-Config contained in slrb-ConfigToAddModList, which is derived through the end-to-end QoS attribute set; 3> If the UE is out of coverage: 4> According to the sl-RadioBearerConfig in SidelinkPreconfigNR, set the SLRB-Config contained in slrb-ConfigToAddModList, which is derived through the end-to-end QoS attribute set; 1> For each additional sidelink RLC bearer to be released, due to sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR or upper layer configuration according to clause 5.8.9.1a.5.1: 2> Set the entry contained in sl-RLC-BearerToReleaseList corresponding to the additional sidelink RLC bearer; 1> for each additional sidelink RLC bearer to be established or modified, according to clause 5.8.9.1a.6.1, due to reception of sl-ConfigDedicatedNR, SIB12, or SidelinkPreconfigNR: 2> If additional sidelink RLC bearers are to be established: 3> Assign a new logical channel identifier for the logical channel to be associated with the sidelink DRB and set sl-MAC-LogicalChannelConfigPC5 in SL-RLC-BearerConfig to include the new logical channel identifier; 2> Set the SL-RLC-BearerConfig contained in sl-RLC-BearerToAddModList according to the received sl-RadioBearerConfig and the sl-RLC-BearerConfig corresponding to the additional sidelink RLC bearer; 1> setting the entry contained in the sl-CarrierToReleaseList corresponding to the sidelink carrier in which the MAC entity indicates that the maximum number of consecutive HARQ DTXs for a particular destination has been reached; 1> Consider at least the carriers mapped to the sidelink QoS flow configured by upper layers, the carriers configured in sl-ConfigDedicatedNR, SIB12 or SidelinkPreconfigNR and the carriers supported by both UEs, and set the entries contained in sl-CarrierToAddModList corresponding to the sidelink carriers; 1>Set sl-MeasConfig as follows: 2> If the frequency used for NR sidelink communication is contained in sl-FreqInfoToAddModList / sl-FreqInfoToAddModListExt in sl-ConfigDedicatedNR in RRCReconfiguration message or in sl-ConfigCommonNR in SIB12: 3> If the UE is in RRC_CONNECTED: 4> Set sl-MeasConfig according to the NR sidelink measurement configuration information stored for this destination; 3> If the UE is in RRC_IDLE or RRC_INACTIVE: 4> Set sl-MeasConfig according to the stored NR sidelink measurement configuration received from SIB12; 2> Otherwise: 3> Set sl-MeasConfig according to sl-MeasPreconfig in SidelinkPreconfigNR; 1>Set sl-LatencyBoundIUC-Report; 1>Start timer T400 for the destination; 1>Set sl-CSI-RS-Config; 1>Set sl-LatencyBoundCSI-Report; 1>Set sl-ResetConfig; NOTE 1: Whether / how to set the parameters included in sl-LatencyBoundIUC-Report, sl-CSI-RS-Config, sl-LatencyBoundCSI-Report and sl-ResetConfig depends on the UE implementation. 1> Set sl-DRX-ConfigUC-PC5 as follows: 2> If the frequency used for NR sidelink communication is contained in sl-FreqInfoToAddModList / sl-FreqInfoToAddModListExt in sl-ConfigDedicatedNR in RRCReconfiguration message or in sl-ConfigCommonNR in SIB12: 3> If the UE is in RRC_CONNECTED and if the sl-ScheduledConfig is contained in the sl-ConfigDedicatedNR within the RRCReconfiguration: 4> Set sl-DRX-ConfigUC-PC5 according to the NR sidelink DRX configuration information stored for this destination; NOTE 2: If the UE is in RRC_IDLE or in RRC_INACTIVE or out of coverage or in RRC_CONNECTED and sl-UE-SelectedConfig is included in sl-ConfigDedicatedNR in RRCReconfiguration, sl-DRX-ConfigUC-PC5 is set depending on the UE implementation. 1> For each PC5 relay RLC channel to be released due to the configuration of sl-ConfigDedicatedNR: 2> Set the SL-RLC-ChannelID corresponding to the PC5 relay RLC channel in sl-RLC-ChannelToReleaseListPC5; 1> For each PC5 relay RLC channel to be established or modified due to receipt of sl-ConfigDedicatedNR: 2> To establish a PC5 relay RLC channel: 3> Assign a new logical channel identifier for the logical channel to be associated with the PC5 relay RLC channel and set sl-MAC-LogicalChannelConfigPC5 in SL-RLC-ChannelConfigPC5 to include the new logical channel identifier; 2> Set the SL-RLC-ChannelConfigPC5 contained in sl-RLC-ChannelToAddModListPC5 according to the received SL-RLC-ChannelConfig corresponding to the relay RLC channel PC5, including setting sl-RLC-ChannelID-PC5 to the same value of sl-RLC-ChannelID received in SL-RLC-ChannelConfig; 1> If the UE acts as an L2 U2N relay UE: 2> If the destination UE is an L2 U2N remote UE that requested SFN-DFN offset in a previous RemoteUEInformationSidelink message: 3> If the SFN-DFN offset has changed since the previous transmission of the RRCReconfigurationSidelink message, or no previous transmission of the RRCReconfigurationSidelink message has occurred since the RemoteUEInformationSidelink message was received: 4> Set sl-SFN-DFN-Offset according to the relationship between the SFN timeline and DFN timeline of PCell; 1> If the UE acts as an L2 U2U relay UE and if a procedure is initiated to configure a local ID pair to a connected L2 U2U remote UE: 2> If a local ID pair is to be allocated or modified for end-to-end PC5 connection, and if a per-hop PC5-RRC connection with this L2U2U remote UE and a per-hop PC5-RRC connection with its peer L2 U2U remote UE are successfully established: Include the entry in sl-LocalID-PairToAddModList and set the fields as follows: 4> set sl-RemoteUE-L2Identity to the source L2 ID of this L2 U2U remote UE according to the association between user information and L2 ID as specified in TS 23.304

[65] , and set sl-RemoteUE-LocalIdentity to include the new local UE ID assigned to this L2U2U remote UE in SL-SRAP-ConfigPC5 (if needed); 4> set sl-PeerRemoteUE-L2Identity to the destination L2ID of the peer L2 U2U remote UE according to the association between user information and L2 ID as specified in TS 23.304

[65] , and set sl-PeerRemoteUE-LocalIdentity to include the new local UE ID assigned to the peer L2 U2U remote UE in SL-SRAP-ConfigPC5 (if needed); 2> Otherwise, if the local ID pair is to be released for use in an end-to-end PC5 connection: 3> include an entry in sl-LocalID-PairToReleaseList with the value of SL-DestinationIdentity set to the destination L2 ID of the peer L2 U2U remote UE; 1> if the UE acts as an L2 U2U remote UE (i.e., Tx UE and is in RRC_IDLE or RRC_INACTIVE or out of coverage), and if a procedure is initiated to add / modify the first-hop PC5 relay RLC channel of the end-to-end sidelink DRB to a connected L2 U2N relay UE (i.e., Rx UE) based on the configuration in SIB12 or SidelinkPreconfigNR; or 1> If the UE acts as an L2 U2U relay UE (i.e., Tx UE) and is in RRC_IDLE or RRC_INACTIVE or out of coverage, and if a procedure is initiated to add / modify a second-hop PC5 relay RLC channel to a connected L2 U2N remote UE (i.e., Rx UE) based on the configuration in SIB12 or SidelinkPreconfigNR: 2> To establish a PC5 relay RLC channel: 3> Allocate a new RLC channel ID and set sl-RLC-ChannelID-PC5 in SL-RLC-ChannelConfigPC5 to include the new RLC channel ID; 3> Assign a new logical channel identifier for the logical channel to be associated with the PC5 relay RLC channel and set sl-MAC-LogicalChannelConfigPC5 in SL-RLC-ChannelConfigPC5 to include the new logical channel identifier; 2> If the UE is in RRC_IDLE or RRC_INACTIVE: 3> Set the SL-RLC-ChannelConfigPC5 contained in sl-RLC-ChannelToAddModListPC5 according to the SL-RLC-BearerConfig derived based on the per-hop QoS of the end-to-end SLRB according to SIB12; 2> Otherwise, if the UE is out of coverage: 3> Set the SL-RLC-ChannelConfigPC5 contained in sl-RLC-ChannelToAddModListPC5 according to the SL-RLC-BearerConfig derived based on the per-hop QoS of the SLRB according to SidelinkPreconfigNR; 1> if the UE acts as an L2 U2U remote UE (i.e., Tx UE) and is in RRC_IDLE or RRC_INACTIVE or out of coverage, and initiates a procedure according to clause 5.8.9.7.1 to release the first-hop PC5 relay RLC channel of the end-to-end side link DRB to a connected L2 U2N relay UE (i.e., Rx UE); or 1> If the UE acts as an L2 U2U relay UE (i.e., Tx UE) and is in RRC_IDLE or RRC_INACTIVE or out of coverage, and initiates a procedure according to clause 5.8.9.7.1 to release the second-hop PC5 relay RLC channel of the end-to-end side link DRB to the connected L2 U2N remote UE (i.e., Rx UE): 2> Set the SL-RLC-ChannelID corresponding to the PC5 relay RLC channel in sl-RLC-ChannelToReleaseListPC5; NOTE 3: If the UE is in RRC_IDLE or in RRC_INACTIVE or out of coverage, how to merge the split per-flow QoS on the first / second hop into the per-SLRB level QoS derived for RLC channel configuration depends on the UE implementation. The UE shall submit an RRCReconfigurationSidelink message to lower layers for transmission. […] 5.8.9.1a Sidelink Radio Bearer Management 5.8.9.1a.1 Sidelink DRB Release 5.8.9.1a.1.1 Sidelink DRB Release Conditions For NR sidelink communications, a sidelink DRB release is initiated in the following situations: 1> For multicast, broadcast, and unicast, if the slrb-Uu-ConfigIndex (if present) of the sidelink DRB is included in the sl-RadioBearerToReleaseList in the sl-ConfigDedicatedNR; or 1> For multicast and broadcast, if no sidelink QoS flow with data indicated by upper layers is mapped to a sidelink DRB for transmission, the sidelink QoS flow is (re)configured by receiving SIB12 or SidelinkPreconfigNR; or 1> for multicast, broadcast, and unicast, if the SL-RLC-BearerConfigIndex (if present) of the associated RLC entity for the sidelink DRB (i.e., including the additional sidelink RLC bearers, if applicable) is contained in the sl-RLC-BearerToReleaseList / sl-RLC-BearerToReleaseListSizeExt in the sl-ConfigDedicatedNR; or 1> for unicast, if no sidelink QoS flow with data indicated by upper layers is mapped to the sidelink DRB for transmission, the sidelink QoS flow is (re)configured by receiving SIB12 or SidelinkPreconfigNR, and if no sidelink QoS flow mapped to the sidelink DRB has data, the sidelink QoS flow is (re)configured by receiving RRCReconfigurationSidelink; or 1> for unicast, if the SLRB-PC5-ConfigIndex (if present) of the sidelink DRB is included in slrb-ConfigToReleaseList in RRCReconfigurationSidelink or if sl-ResetConfig is included in RRCReconfigurationSidelink; or 1> for unicast, when the corresponding PC5-RRC connection is released due to detection of sidelink RLF according to clause 5.8.9.3; or 1> for unicast, when the corresponding PC5-RRC connection is released due to a request from upper layers in accordance with clause 5.8.9.5; or 1> For L2 U2U relay operation, when according to the conditions 5.8.9.3a or 5.8.9.3b When the corresponding end-to-end PC5 connection failure / release is detected; or 1> For L2 U2U relay operation, if no sidelink QoS flow indicated by the source L2U2U remote UE is mapped to an end-to-end sidelink DRB for transmission when the UE acts as a L2 U2N relay UE. 5.8.9.1a.1.2 Sidelink DRB Release Operation For each sidelink DRB for which the sidelink DRB release conditions are met as in clause 5.8.9.1a.1.1, an NR sidelink capable UE configured by upper layers to perform NR sidelink communication shall: 1> for multicast and broadcast; or 1> For unicast, if the sidelink DRB release is triggered after receiving the RRCReconfigurationSidelink message; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB release is triggered due to the configuration received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR or indicated by upper layers: 2> Release the PDCP entity associated with the sidelink DRB for NR sidelink communication; 2> If the SDAP entity for NR sidelink communication associated with this sidelink DRB is configured as: 3> Indicate the release of the sidelink DRB to the SDAP entity associated with this sidelink DRB (TS 37.324

[24] , clause 5.3.3); 2> Release the SDAP entity (if any) that does not have an associated sidelink DRB as specified in TS 37.324

[24] clause 5.1.2 for NR sidelink communication; 1> for multicast and broadcast; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB release is triggered due to the configuration received in sl-ConfigDedicatedNR: 2> For each sl-RLC-BearerConfigIndex included in the received sl-RLC-BearerToReleaseList / sl-RLC-BearerToReleaseListSizeExt as part of the current UE-side link configuration: 3> Release the RLC entity and corresponding logical channel used for NR sidelink communication, where the NR sidelink communication is associated with sl-RLC-BearerConfigIndex. 1> For unicast, if the sidelink DRB release is triggered by receiving an RRCReconfigurationSidelink message; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB release is triggered due to the configuration received in SIB12, SidelinkPreconfigNR or indicated by upper layers: 2> Release the RLC entity and corresponding logical channel associated with the sidelink DRB for NR sidelink communication; 2> Perform the sidelink UE information procedure for unicast in clause 5.8.3 when necessary. 1> If a sidelink radio link failure is detected for a particular destination: 2> Release the PDCP entity, RLC entity and logical channel used for the sidelink DRB of a specific destination. 1> If the sidelink DRB is an end-to-end sidelink DRB in L2 U2U relay operation: 2> If there are no other end-to-end side link DRBs associated with this RLC channel, perform PC5 relay RLC channel release according to 5.8.9.7.1; 2> If the UE acts as a source L2 U2U remote / relay UE and is in RRC_CONNECTED: 3> reconfigure the SRAP entity for the sidelink DRB according to the sl-SRAP-ConfigU2U received in the sl-ConfigDedicatedNR (if included); 2> Otherwise, if the UE acts as a source L2 U2U remote UE / relay and is in RRC_IDLE or RRC_INACTIVE: 3> Reconfigure the SRAP entity for the sidelink DRB derived based on the configuration received in SIB12; 2> Otherwise, if the UE acts as a source L2 U2U remote / relay UE and is out of coverage: 3> Reconfigure the SRAP entity for the sidelink DRB derived based on the configuration received in SidelinkPreconfigNR; 5.8.9.1a.2 Sidelink DRB Addition / Modification 5.8.9.1a.2.1 Sidelink DRB Addition / Modification Conditions For NR sidelink communication, sidelink DRB addition is initiated only in the following cases: 1> if any sidelink QoS flow is (re)configured by sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR and will be mapped to a sidelink DRB that is not established; or 1> If any sidelink QoS flow is (re)configured by RRCReconfigurationSidelink and will be mapped to an unestablished sidelink DRB; 1> if any sidelink QoS flow is (re)configured by the source L2 U2U remote UE and mapped to an end-to-end sidelink DRB for transmission when the UE acts as an L2 U2N relay UE; For NR sidelink communications, sidelink DRB modification is initiated only in the following cases: 1> If, for an established sidelink DRB, any of the sidelink DRB-related parameters are changed via sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR, or RRCReconfigurationSidelink; 5.8.9.1a.2.2 Sidelink DRB Add / Modify Operation For a sidelink DRB for which the sidelink DRB addition conditions are met as in clause 5.8.9.1a.2.1, an NR sidelink capable UE configured by upper layers to perform NR sidelink communication shall: 1> for multicast and broadcast; or 1> For unicast, if the sidelink DRB addition is triggered due to the reception of an RRCReconfigurationSidelink message; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB addition is triggered due to the configuration received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR or indicated by upper layers: 2> If there is no SDAP entity for NR sidelink communication associated with the destination and broadcast type of the sidelink DRB: 3> establish the SDAP entity for NR sidelink communication as specified in TS 37.324

[24] clause 5.1.1; 2> (Re)configure the SDAP entity according to the sl-SDAP-ConfigPC5 received in RRCReconfigurationSidelink or the sl-SDAP-Config received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR associated with the sidelink DRB; 2> establish a PDCP entity for NR sidelink communication and configure it according to the sl-PDCP-ConfigPC5 received in RRCReconfigurationSidelink or the sl-PDCP-Config received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR associated with the sidelink DRB; 2> For per-hop sidelink DRB (i.e., UE performs NR sidelink communication with peer UE): 3> Establish an RLC entity for NR sidelink communication and configure it according to the sl-RLC-ConfigPC5 received in RRCReconfigurationSidelink or the sl-RLC-Config received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR associated with the sidelink DRB; 3> If this procedure is due to receiving an RRCReconfigurationSidelink message: 4> configure the MAC entity with the logical channel according to the sl-MAC-LogicalChannelConfigPC5 received in RRCReconfigurationSidelink associated with the sidelink DRB and perform the Sidelink UE Information procedure in clause 5.8.3 for unicast if required; 3> Otherwise, if this procedure is due to receipt of an RRCReconfigurationCompleteSidelink message: 4> Configure the MAC entity with the logical channel associated with the sidelink DRB according to the sl-MAC-LogicalChannelConfig received in sl-ConfigDedicatedNR, SIB12, and SidelinkPreconfigNR; 3> Otherwise (i.e., for multicast / broadcast): 4> Configure the MAC entity with the logical channel associated with the sidelink DRB according to the sl-MAC-LogicalChannelConfig received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR, and allocate a new LCID to this logical channel. 2> For end-to-end side link DRB (i.e., UE acts as L2 U2U remote UE): 3> If the UE is in RRC_CONNECTED: 4> Associate this end-to-end side link DRB with the PC5 RLC channel indicated by sl-EgressRLC-ChannelPC5 contained in sl-ConfigDedicatedNR received from RRCReconfiguration; 3> Otherwise, if the UE is in RRC_IDLE or RRC_INACTIVE: 4> Based on the configuration in SIB12, the PC5 RLC channel derived through the per-SLRB QoS attribute set of this end-to-end side link DRB is regarded as an egress PC5 relay RLC channel; 4> Associate this end-to-end side link DRB with the PC5 RLC channel and configure the mapping to the SRAP; 3> Otherwise, if the UE is out of coverage: 4> Based on the configuration in SidelinkPreconfigNR, the PC5 RLC channel derived through the per-SLRB QoS attribute set of this end-to-end side link DRB is considered as an egress PC5 relay RLC channel; 4> Associate this end-to-end side link DRB with the PC5 RLC channel and configure the mapping to the SRAP; NOTE 1: When the sidelink DRB addition is due to the configuration of RRCReconfigurationSidelink, it is up to the UE implementation to select the sidelink DRB configuration that transmits the parameters of the sidelink DRB as needed from the received sl-ConfigDedicatedNR (if in RRC_CONNECTED), SIB12 (if in RRC_IDLE / INACTIVE), SidelinkPreconfigNR (if out of coverage) with the same RLC mode as configured in RRCReconfigurationSidelink. For a sidelink DRB for which the sidelink DRB modification conditions in clause 5.8.9.1a.2.1 are met, a UE capable of NR sidelink communication that is configured by upper layers to perform NR sidelink communication shall: 1> for multicast and broadcast; or 1> For unicast, if the sidelink DRB modification is triggered by receiving an RRCReconfigurationSidelink message; or 1> For unicast, after receiving the RRCReconfigurationCompleteSidelink message, if the sidelink DRB modification is triggered due to the configuration received in sl-ConfigDedicatedNR, SIB12 or SidelinkPreconfigNR: 2> Reconfigure the SDAP entity of the sidelink DRB according to the sl-SDAP-ConfigPC5 received in RRCReconfigurationSidelink or the sl-SDAP-Config received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR (if included); 2> reconfigure the PDCP entity for the sidelink DRB according to the sl-PDCP-ConfigPC5 received in RRCReconfigurationSidelink or the sl-PDCP-Config received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR (if included); 2> Reconfigure the RLC entity of the sidelink DRB according to the sl-RLC-ConfigPC5 received in RRCReconfigurationSidelink or the sl-RLC-Config received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR (if included); 2> Reconfigure the logical channels of the sidelink DRB according to the sl-MAC-LogicalChannelConfigPC5 received in RRCReconfigurationSidelink or the sl-MAC-LogicalChannelConfig received in sl-ConfigDedicatedNR, SIB12, SidelinkPreconfigNR (if included). 2> If the UE is in RRC_CONNECTED: 3> reconfigure the SRAP entity for the sidelink DRB according to the sl-SRAP-ConfigU2U received in the sl-ConfigDedicatedNR (if included); 2> Otherwise, if the UE is in RRC_IDLE or RRC_INACTIVE: 3> Reconfigure the SRAP entity for the sidelink DRB derived based on the configuration received in SIB12; 2> Otherwise, if the UE is out of coverage: 3> Reconfigure the SRAP entity for the sidelink DRB derived based on the configuration received in SidelinkPreconfigNR. […] 5.8.9.7 PC5 Relay RLC Channel Management for L2 U2N or U2U Relay 5.8.9.7.1 PC5 Relay RLC Channel Release The UE shall: 1> If the PC5 relay RLC channel release is triggered after receiving the RRCReconfigurationSidelink message; or 1> After receiving the RRCReconfigurationCompleteSidelink message, if the PC5 relay RLC channel release is triggered due to the configuration received in sl-ConfigDedicatedNR: 2> For each SL-RLC-ChannelID in the sl-RLC-ChannelToReleaseList received in the sl-ConfigDedicatedNR within the RRCReconfiguration, or for each SL-RLC-ChannelID included in the received sl-RLC-ChannelToReleaseListPC5 as part of the current UE-side link configuration: 3> Release the RLC entity and the corresponding logical channel associated with SL-RLC-ChannelID; 1> If the PC5 relay RLC channel release is triggered by an end-to-end DRB release as specified in 5.8.9.1a.1.2: 2> Release the RLC entity and the corresponding logical channel; 1> If PC5 relay RLC channel release is triggered by upper layers for a specific destination as specified in 5.8.9.5 or due to sidelink RLF as specified in 5.8.9.3: 2> Release the RLC entity and the corresponding logical channel associated with the SL-RLC-ChannelID of the specific destination; 5.8.9.7.2 PC5 Relay RLC Channel Addition / Modification After establishing a PC5-RRC connection between the L2 U2N relay UE and the L2 U2N remote UE, the L2 U2N relay UE shall: 1> If the SRAP entity has not yet been established, establish the SRAP entity as specified in TS 38.351

[66] ; 1> Apply the RLC-specific configuration of SL-RLC0 as specified in clause 9.1.1.4: 1> If the L2 U2N relay UE is in RRC_IDLE / INACTIVE state, the RLC preset configuration of SL-RLC1 as defined in clause 9.2.4 applies; After a PC5-RRC connection is established between two UEs for L2 U2U relay operation, the UEs shall: 1> If the SRAP entity has not yet been established, establish the SRAP entity as specified in TS 38.351

[66] ; 1> Apply the RLC-specific configuration of SL-U2U-RLC as specified in clause 9.1.1.4; For L2 U2U relay operation in RRC_IDLE / RRC_INACTVE or out of coverage, PC5 relay RLC channel addition / modification may be triggered due to the addition / modification / release of end-to-end SL DRBs. The source L2 U2U remote UE and L2 U2N relay UE derive the corresponding PC5 relay RLC channel based on SIB12 / pre-configuration as follows: -The source L2 U2U remote UE derives the configuration of the PC5 relay RLC channel (i.e., the first-hop PC5 relay RLC channel) between the L2 U2U source remote UE and the L2U2U relay UE by aggregating the split QoS attribute sets of the first hop into a per-SLRB level QoS attribute set for each end-to-end SL DRB, and considering the SL-RLC-Config (linked to the SL-RadioBearerConfig matching the per-SLRB level QoS attribute set) as the first-hop RLC channel configuration. -The L2 U2U relay UE derives the configuration of the PC5 relay RLC channel (i.e., the second-hop PC5 relay RLC channel) between the L2U2U relay UE and the target L2U2U source remote UE by aggregating the split QoS attribute sets of the second hop into a per-SLRB-level QoS attribute set for each end-to-end SL DRB, and considering the SL-RLC-Config (linked to the SL-RadioBearerConfig matching the per-SLRB-level QoS attribute set) as the second-hop RLC channel configuration. The UE shall: 1> If the PC5 relay RLC channel addition / modification is triggered by receiving an RRCReconfigurationSidelink message; or 1> After receiving the RRCReconfigurationCompleteSidelink message, if PC5 relay RLC channel addition / modification is triggered due to the configuration received in sl-ConfigDedicatedNR; or 1> After receiving the RRCReconfigurationCompleteSidelink message, if PC5 relay RLC channel addition / modification is triggered for the end-to-end sidelink DRB based on the configuration in SIB12 or SidelinkPreconfigNR: 2> if the current configuration contains a PC5 relay RLC channel with the received sl-RLC-ChannelID or sl-RLC-ChannelID-PC5; or 2> If the configuration in SIB12 or SidelinkPreconfigNR has been updated, derive the PC5 relay RLC channel based on the configuration: 3> Reconfigure the sidelink RLC entity according to the received sl-RLC-Config or sl-RLC-ConfigPC5; 3> Reconfigure the sidelink MAC entity with the logical channel according to the received sl-MAC-LogicalChannelConfig or sl-MAC-LogicalChannelConfigPC5; 2> Otherwise (PC5 relay RLC channel with received sl-RLC-ChannelID or sl-RLC-ChannelID-PC5 has not been configured before): 3> Establish a sidelink RLC entity according to the received sl-RLC-Config (in sl-ConfigDedicatedNR or SIB12 or SidelinkPreconfigNR) or sl-RLC-ConfigPC5; 3> Configure the sidelink MAC entity with the logical channel according to the received sl-MAC-LogicalChannelConfig or sl-MAC-LogicalChannelConfigPC5. […] -SIB12 SIB12 contains the NR sidelink communication / discovery configuration. SIB12 Information Elements Editor's Note: Whether new L3 U2U trunk-specific indications are needed is for further study. Editor's Note: Mapping configuration (from e2e SLRB to RLC channels) is required during pre-configuration. The existing table format is used as a baseline and will be discussed during maintenance. […] -SL-RLC-ChannelConfig The IE SL-RLC-ChannelConfig specifies configuration information for a PC5 relay RLC channel between an L2 U2N relay UE and an L2 U2N remote UE or between an L2 U2U remote UE and an L2 U2U relay UE. SL-RLC-ChannelConfig information element

[0050] 3GPP TS 23.304 describes support for Rel-18 single-hop inter-UE relay. Specifically, a relay user equipment (UE) can be used to support communication between two (Layer 2 or Layer 3) Proximity-Based Service (ProSe) end UEs that are unable to communicate directly with each other. The inter-UE relay UE establishes a PC5 link with each of two ProSe end UEs, including a source ProSe end UE (e.g., on the first PC5 hop) and a target ProSe end UE (e.g., on the second PC5 hop), to forward traffic for the ProSe service of interest between the two ProSe end UEs.

[0051] To establish a PC5 link, the Layer 2 link establishment procedure without integrated discovery as specified in 3GPP TS 23.304, as specified in clause 6.7.1, or the Layer 2 link establishment procedure with integrated discovery as specified in 3GPP TS 23.304, as specified in clause 6.7.3, may be used. A PC5 link may be associated with a relay service code and may support one or more services / applications identified by one or more ProSe identifiers.

[0052] According to 3GPP TS 38.300, after establishing inter-UE (UE-to-UE, U2U) relay communication, the relay UE can allocate / assign a local UE identity / identifier (ID) to each end UE (i.e., source UE or target UE). According to 3GPP TS 38.331, the local UE ID and layer 2 ID of the end UE are sent to the peer UE together with the local UE ID and layer 2 ID of the peer UE using a PC5 RRC message (i.e., RRCReconfigurationSidelink). It should be noted that the source UE can establish one or more end-to-end (end-to-end, E2E) sidelink (SL) data radio bearers (DRBs) with the target UE to support U2U relay communication via the relay UE.

[0053] If this UE is in RRC_IDLE or RRC_INACTIVE, the configuration for establishing one or more end-to-end SL DRBs can be derived from SIB12. In addition, each of the one or more end-to-end SL DRBs can be mapped to a PC5 relay radio link control (RLC) channel. Therefore, the source UE and the relay UE can establish one or more PC5 relay RLC channels on the first hop to support transmission from the source UE to the relay UE. The configuration for establishing one or more PC5 relay RLC channels can be derived from SIB12. It should be noted that the source UE can send end-to-end QoS information for each PC5 QoS flow to the relay UE for PC5 QoS splitting (by using, for example, UEInformationRequestSidelink), and then the relay UE can respond to the split QoS information to the source UE (by using, for example, UEInformationResponseSidelink). Based on the split QoS information, the source UE can then establish a PC5 relay RLC channel derived from the split QoS information of the end-to-end SL DRB based on the configuration in SIB12 (for example, the source UE can select a PC5 relay RLC channel configuration of the split PDB in the split QoS information in which the side link packet delay budget can meet the split QoS information), and then associate this end-to-end SL DRB with this PC5 relay RLC channel.

[0054] It is possible that the SIB12 in the serving cell may be updated, the UE may move to another cell (and thus apply the SIB12 of this cell), the UE may move out of cell coverage (and thus apply SidelinkPreconfigNR instead of SIB12), or the UE may return to cell coverage (and thus apply SIB12 instead of SidelinkPreconfigNR). In such scenarios, an end-to-end (E2E) SL DRB may be mapped from a PC5 relay RLC channel to another PC5 relay RLC channel, and thus there may not be an E2E SL DRB mapped to a PC5 relay RLC channel. For example, the source UE may initially establish a first E2E SL DRB, a second E2E SL DRB, a first PC5 relay RLC channel (on the first hop), and a second PC5 relay RLC channel (on the first hop). When one of the above scenarios occurs, the source UE may need to apply a new PC5 relay RLC channel configuration that can meet the QoS requirements of the first E2E SL DRB and the second E2E SL DRB. In this case, the source UE may only need one PC5 relay RLC channel. Therefore, the source UE can reconfigure one PC5 relay RLC channel (e.g., the second PC5 relay RLC channel) to serve the first E2E SL DRB and the second E2E SL DRB, and therefore, the unused PC5 relay RLC channel (e.g., the first PC5 relay RLC channel) should be released. However, this scenario is not covered in 3GPP Email Discussion [Post125]

[402] [Relay] 38.331 Rel-18 Relay CR (Huawei) because there is no condition for triggering the release of the PC5 relay RLC channel in the case of sidelink DRB modification. If the source UE is implemented based on 3GPP Email Discussion [Post125]

[402] [Relay] 38.331 Rel-18 Relay CR (Huawei), it will not release the unused PC5 relay RLC channel, and thus will cause UE memory consumption.

[0055] To address the issue, an example of a text proposal of a source UE in addition to 3GPP Email Discussion [Post125]

[402] [Relay] 38.331Rel-18 Relay CR (Huawei) is described below. Specifically, in response to an end-to-end DRB modification (e.g., for remapping a first E2E SL DRB from a first PC5 relay RLC channel to a second PC5 relay RLC channel), if no other end-to-end sidelink DRB associated with the first PC5 relay RLC channel exists, the source UE may perform a PC5 relay RLC channel release to release the first PC5 relay RLC channel.

[0056] Figure 20 2000 is a flowchart for a first-end user equipment (UE). In step 2005, the first-end UE establishes a PC5 connection with a relay UE to support inter-UE relay communication between the first-end UE and the second-end UE via the relay UE. In step 2010, the first-end UE establishes an end-to-end SL DRB and associates the end-to-end SL DRB with a first PC5 relay RLC channel to support inter-UE relay communication. In step 2015, the first-end UE modifies the end-to-end SL DRB to associate it with a second PC5 relay RLC channel. In step 2020, if there is no end-to-end SL DRB mapped to the first PC5 relay RLC channel, the first-end UE releases the first PC5 relay RLC channel in response to the modification of the end-to-end SL DRB.

[0057] In one embodiment, a first-end UE may receive first system information in a first cell, wherein the first system information includes information for deriving the configuration of a first PC5 relay RLC channel. The first-end UE may receive second system information in the first cell or a second cell, wherein the second system information includes information for deriving the configuration of a second PC5 relay RLC channel. In response to receiving the first system information, the first-end UE may send a first PC5-RRC message to the relay UE to establish the first PC5 relay RLC channel. In response to receiving the second system information, the first-end UE may send a second PC5-RRC message to the relay UE to modify the first PC5 relay RLC channel.

[0058] In one embodiment, the first / second system information may be SIB12. The first end UE may be in RRC_IDLE or RRC_INACTIVE. The first / second PC5-RRC message may be an RRCReconfigurationSidelink message.

[0059] Return Reference Figure 3 and 4, in an exemplary embodiment, from the perspective of the first-end UE. The first-end UE 300 includes program code 312 stored in the memory 310. The CPU 308 can execute the program code 312 to enable the first-end UE to: (i) establish a PC5 connection with the relay UE to support inter-UE relay communication between the first-end UE and the second-end UE via the relay UE, (ii) establish an end-to-end SL DRB and associate the end-to-end SL DRB with a first PC5 relay RLC channel to support inter-UE relay communication, (iii) modify the end-to-end SL DRB to associate it with the second PC5 relay RLC channel, and (iv) if there is no end-to-end SL DRB mapped to the first PC5 relay RLC channel, release the first PC5 relay RLC channel in response to the modification of the end-to-end SL DRB. In addition, the CPU 308 can execute the program code 312 to perform all of the above actions and steps or other actions and steps described herein.

[0060] On the other hand, the relay UE may establish a third PC5 relay RLC channel (on the second hop) for serving the first E2E SL DRB, and establish a fourth PC5 relay RLC channel (on the second hop) for serving the second E2E SL DRB for transmission from the relay UE to the target UE. If one of the above scenarios occurs, the relay UE may reconfigure a PC5 relay RLC channel (e.g., the fourth PC5 relay RLC channel) for serving the first E2E SL DRB and the second E2E SL DRB, and therefore, the unused PC5 relay RLC channel (e.g., the third PC5 relay RLC channel) should be released. This scenario is not covered in 3GPP Email Discussion [Post125]

[402] [Relay] 38.331 Rel-18 Relay CR (Huawei) because there is no condition for triggering the release of the PC5 relay RLC channel when SIB12 changes. Similarly, if the relay UE is implemented based on 3GPP Email Discussion [Post125]

[402] [Relay] 38.331 Rel-18 Relay CR (Huawei), it will not release the unused PC5 relay RLC channels and thus will cause UE memory consumption.

[0061] To address the issue, an example of a text proposal for an L2 U2U relay UE in addition to 3GPP Email Discussion [Post125]

[402] [Relay] 38.331Rel-18 Relay CR (Huawei) may be described below. Specifically, if no other end-to-end sidelink DRBs are associated with the third PC5 relay RLC channel, then in response to remapping the first E2E SL DRB from the third PC5 relay RLC channel to the fourth PC5 relay RLC channel (due to, for example, SIB12 or SidelinkPreconfigNR), the relay UE may perform a PC5 relay RLC channel release to release the third PC5 relay RLC channel.

[0062] Figure 21 21 is a flowchart for a first-end user equipment (UE). In step 2105, the first-end UE establishes a PC5 connection with a relay UE to support inter-UE relay communication between the first-end UE and the second-end UE via the relay UE. In step 2110, the first-end UE establishes a first end-to-end side link (SL) data radio bearer (DRB) and associates the first end-to-end SL DRB with a first PC5 relay radio link control (RLC) channel to support inter-UE relay communication, wherein the first PC5 relay RLC channel is established between the first-end UE and the relay UE. In step 2115, the first-end UE establishes a second end-to-end SL DRB and associates the second end-to-end SL DRB with a second PC5 relay RLC channel to support inter-UE relay communication, wherein the second PC5 relay RLC channel is established between the first-end UE and the relay UE. In step 2120, the first-end UE determines to use the second PC5 relay RLC channel to provide services for the first end-to-end SL DRB and the second end-to-end SL DRB. In step 2125 , in response to determining to use the second PC5 relay RLC channel to serve the first end-to-end SL DRB and the second end-to-end SLDRB, the first-end UE releases the first PC5 relay RLC channel.

[0063] In one embodiment, a first end-to-end SL DRB and a second end-to-end SL DRB may be established between a first-end UE and a second-end UE. After determining to use a second PC5 relay RLC channel to serve the first end-to-end SL DRB and the second end-to-end SL DRB and releasing the first PC5 relay RLC channel, the second PC5 relay RLC channel may still be associated with the second end-to-end SL DRB.

[0064] In one embodiment, a second PC5 relay RLC channel may be established based on the first system information to serve the second end-to-end SL DRB, and may be determined based on the second system information or pre-configuration to serve the first end-to-end SL DRB and the second end-to-end SL DRB, or may be derived from the second system information or pre-configuration to serve the first end-to-end SL DRB and the second end-to-end SL DRB. A second PC5 relay RLC channel may be established based on the pre-configuration to serve the second end-to-end SL DRB, and may be determined based on the system information to serve the first end-to-end SL DRB and the second end-to-end SL DRB, or may be derived from the system information to serve the first end-to-end SL DRB and the second end-to-end SL DRB.

[0065] In one embodiment, the PC5 connection may be a layer 2 link, a unicast link, or a PC5 radio resource control (RRC) connection. The (first / second) system information may be SIB12.

[0066] Return Reference Figure 3 and 4 In an exemplary embodiment, from the perspective of a first-end UE, the first-end UE 300 includes program code 312 stored in a memory 310 . The CPU 308 can execute the program code 312 to enable the first-end UE to: (i) establish a PC5 connection with the relay UE to support inter-UE relay communication between the first-end UE and the second-end UE via the relay UE, (ii) establish a first end-to-end SL DRB and associate the first end-to-end SL DRB with a first PC5 relay RLC channel to support inter-UE relay communication, wherein the first PC5 relay RLC channel is established between the first-end UE and the relay UE, (iii) establish a second end-to-end SL DRB and associate the second end-to-end SL DRB with a second PC5 relay RLC channel to support inter-UE relay communication, wherein the second PC5 relay RLC channel is established between the first-end UE and the relay UE, (iv) determine to use the second PC5 relay RLC channel to serve the first end-to-end SL DRB and the second end-to-end SL DRB, and (v) release the first PC5 relay RLC channel in response to determining to use the second PC5 relay RLC channel to serve the first end-to-end SL DRB and the second end-to-end SL DRB. Furthermore, CPU 308 may execute program code 312 to perform all of the above-described actions and steps or other actions and steps described herein.

[0067] Figure 222200 is a flowchart for a relay user equipment (UE). In step 2205, the relay UE establishes a PC5 connection with the second-end UE to support inter-UE relay communication between the first-end UE and the second-end UE via the relay UE. In step 2210, the relay UE associates a first PC5 relay radio link control (RLC) channel with a first end-to-end side link (SL) data radio bearer (DRB) to support inter-UE relay communication, wherein the first PC5 relay RLC channel is established between the relay UE and the second-end UE. In step 2215, the relay UE associates a second PC5 relay RLC channel with a second end-to-end SL DRB to support inter-UE relay communication, wherein the second PC5 relay RLC channel is established between the relay UE and the second-end UE. In step 2220, the relay UE determines to use the second PC5 relay RLC channel to provide service for the first end-to-end SL DRB and the second end-to-end SL DRB. In step 2225, the relay UE releases the first PC5 relay RLC channel in response to determining to use the second PC5 relay RLC channel to serve the first end-to-end SL DRB and the second end-to-end SL DRB.

[0068] In one embodiment, the second PC5 relay RLC channel may still be associated with the second end-to-end SL DRB after modification. The second PC5 relay RLC channel may be established based on the first system information to serve the second end-to-end SL DRB, and may be determined or modified based on the second system information or preconfiguration to serve the first end-to-end SL DRB and the second end-to-end SL DRB, or may be derived from the second system information or preconfiguration to serve the first end-to-end SL DRB and the second end-to-end SL DRB. The second PC5 relay RLC channel may be established based on preconfiguration to serve the second end-to-end SL DRB, and may be determined or modified based on the system information to serve the first end-to-end SL DRB and the second end-to-end SL DRB, or may be derived from the system information to serve the first end-to-end SL DRB and the second end-to-end SL DRB.

[0069] In one embodiment, the PC5 connection may be a layer 2 link, a unicast link, or a PC5 radio resource control (RRC) connection. The (first / second) system information may be SIB12.

[0070] Return Reference Figure 3 and 4In an exemplary embodiment, from the perspective of a first-end UE, the first-end UE 300 includes program code 312 stored in a memory 310 . The CPU 308 can execute the program code 312 to enable the first-end UE to: (i) establish a PC5 connection with the second-end UE to support inter-UE relay communication between the first-end UE and the second-end UE via the relay UE, (ii) associate a first PC5 RLC channel with a first end-to-end SL DRB to support inter-UE relay communication, wherein the first PC5 relay RLC channel is established between the relay UE and the second-end UE, (iii) associate a second PC5 relay RLC channel with a second end-to-end SL DRB to support inter-UE relay communication, wherein the second PC5 relay RLC channel is established between the relay UE and the second-end UE, (iv) determine to use the second PC5 relay RLC channel to serve the first end-to-end SL DRB and the second end-to-end SL DRB, and (v) in response to determining to use the second PC5 relay RLC channel to serve the first end-to-end SL DRB and the second end-to-end SL DRB, release the first PC5 relay RLC channel. Furthermore, CPU 308 may execute program code 312 to perform all of the above-described actions and steps or other actions and steps described herein.

[0071] Various aspects of the present disclosure have been described above. It should be understood that the teachings herein can be implemented in a wide variety of forms, and any specific structure, function, or both disclosed herein are merely representative. Based on the teachings herein, those skilled in the art will appreciate that the aspects disclosed herein can be implemented independently of any other aspects, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement a device or practice a method. In addition, other structures, functionalities, or structures and functionalities other than or different from the one or more aspects described herein can be used to implement such a device or practice such a method. As examples of some of the above concepts, in some aspects, parallel channels can be established based on pulse repetition frequency. In some aspects, parallel channels can be established based on pulse position or offset. In some aspects, parallel channels can be established based on time hopping sequences. In some aspects, parallel channels can be established based on pulse repetition frequency, pulse position or offset, and time hopping sequences.

[0072] Those skilled in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0073] Those skilled in the art will further appreciate that the various illustrative logical blocks, modules, processors, components, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two, which may be designed using source coding or some other technique), and various forms of programs or design code with instructions (which, for convenience, may be referred to herein as "software" or "software modules"), or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in varying ways for each specific application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

[0074] In addition, the various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within or performed by an integrated circuit ("IC"), an access terminal, or an access point. An IC may include 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 device, discrete gate or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or any combination thereof designed to perform the functions described herein, and may execute code or instructions residing within the IC, external to the IC, or both. 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, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0075] It should be understood that any specific order or hierarchy of steps in any disclosed process is an example of an exemplary method. It should be understood that the specific order or hierarchy of steps in a process may be rearranged based on design preferences while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy presented.

[0076] The steps of the methods or algorithms described in conjunction with the various aspects disclosed herein can be implemented directly in hardware, in software modules executed by a processor, or in a combination of the two. The software modules (e.g., containing executable instructions and associated data) and other data can reside in a data storage device, such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of computer-readable storage media known in the art. An example storage medium can be coupled to a machine, such as a computer / processor (for convenience, the machine may be referred to herein as a "processor"), such that the processor can read information (e.g., code) from the storage medium and write information to the storage medium. An example storage medium can be integrated with the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user device. In an alternative, the processor and storage medium can reside in the user device as discrete components. In addition, in some aspects, any suitable computer program product can include a computer-readable medium that includes code related to one or more of the various aspects of the present disclosure. In some aspects, the computer program product can include packaging materials.

[0077] Although the present invention has been described in conjunction with various aspects, it will be understood that the invention is capable of further modification. This application is intended to cover any variations, uses, or adaptations of the invention that generally follow the principles of the invention and include such departures from the present disclosure as come within the scope of known and customary practice in the art to which the invention pertains.

Claims

1. A method for a first end user device, characterized in that: include: The first-end user equipment establishes a PC5 connection with the relay user equipment to support inter-user equipment relay communication between the first-end user equipment and the second-end user equipment via the relay user equipment; The first end user equipment establishes a first end-to-end sidelink data radio bearer and associates the first end-to-end sidelink data radio bearer with a first PC5 relay radio link control channel for supporting the inter-user equipment relay communication, wherein the first PC5 relay radio link control channel is established between the first end user equipment and the relay user equipment; The first end user equipment establishes a second end-to-end sidelink data radio bearer and associates the second end-to-end sidelink data radio bearer with a second PC5 relay radio link control channel for supporting the inter-user equipment relay communication, wherein the second PC5 relay radio link control channel is established between the first end user equipment and the relay user equipment; The first end user equipment determines to use the second PC5 relay radio link control channel to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer; and In response to determining to use the second PC5 relay radio link control channel to serve the first end-to-end sidelink data radio bearer and the second end-to-end sidelink data radio bearer, the first end user equipment releases the first PC5 relay radio link control channel.

2. The method according to claim 1, characterized in that The first end-to-end sidelink data radio bearer and the second end-to-end sidelink data radio bearer are established between the first end user equipment and the second end user equipment.

3. The method according to claim 1, characterized in that After determining to use the second PC5 relay radio link control channel to serve the first end-to-end sidelink data radio bearer and the second end-to-end sidelink data radio bearer, the second PC5 relay radio link control channel is still associated with the second end-to-end sidelink data radio bearer.

4. The method according to claim 1, wherein The second PC5 relay radio link control channel is established based on the first system information to serve the second end-to-end side link data radio bearer, and is determined based on the second system information or preconfiguration to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer, or is derived from the second system information or preconfiguration to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer, and / or wherein the first / second system information is SIB12.

5. The method according to claim 1, wherein The second PC5 relay radio link control channel is established based on pre-configuration to serve the second end-to-end side link data radio bearer, and is determined and modified based on system information to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer, or is derived according to the system information to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer.

6. The method according to claim 1, characterized in that The PC5 connection is a layer 2 link, a unicast link or a PC5 radio resource control connection.

7. The method according to claim 5, characterized in that The system information is SIB12.

8. A first end user equipment, characterized in that: include: control circuit; a processor installed in the control circuit; as well as a memory installed in the control circuit and operatively coupled to the processor; wherein the processor is configured to execute program code stored in the memory to: Establishing a PC5 connection with a relay user device to support inter-user device relay communication between the first-end user device and the second-end user device via the relay user device; establishing a first end-to-end sidelink data radio bearer and associating the first end-to-end sidelink data radio bearer with a first PC5 relay radio link control channel for supporting the inter-UE relay communication, wherein the first PC5 relay radio link control channel is established between the first end UE and the relay UE; establishing a second end-to-end sidelink data radio bearer and associating the second end-to-end sidelink data radio bearer with a second PC5 relay radio link control channel for supporting the inter-UE relay communication, wherein the second PC5 relay radio link control channel is established between the first end UE and the relay UE; determining to use the second PC5 relay radio link control channel to serve the first end-to-end sidelink data radio bearer and the second end-to-end sidelink data radio bearer; as well as In response to determining to use the second PC5 relay radio link control channel to serve the first end-to-end sidelink data radio bearer and the second end-to-end sidelink data radio bearer, releasing the first PC5 relay sidelink data radio bearer channel.

9. The first end user equipment according to claim 8, characterized in that The first end-to-end sidelink data radio bearer and the second end-to-end sidelink data radio bearer are established between the first end user equipment and the second end user equipment.

10. The first end user equipment according to claim 8, characterized in that After determining to use the second PC5 relay radio link control channel to serve the first end-to-end sidelink data radio bearer and the second end-to-end sidelink data radio bearer, the second PC5 relay radio link control channel remains associated with the second end-to-end sidelink data radio bearer.

11. The first end user equipment according to claim 8, characterized in that The second PC5 relay radio link control channel is established based on the first system information to serve the second end-to-end side link data radio bearer, and is determined based on the second system information or preconfiguration to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer, or is derived from the second system information or the preconfiguration to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer, and / or wherein the first / second system information is SIB12.

12. The first end user equipment according to claim 8, characterized in that The second PC5 relay radio link control channel is established based on pre-configuration to serve the second end-to-end side link data radio bearer, and is determined to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer based on system information, or is derived from the system information to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer.

13. The first end user equipment according to claim 8, characterized in that The PC5 connection is a layer 2 link, a unicast link or a PC5 radio resource control connection.

14. The first end user equipment according to claim 12, characterized in that The system information is SIB12.

15. A method for relaying user equipment, characterized in that: include: The relay user equipment establishes a PC5 connection with the second end user equipment to support inter-user equipment relay communication between the first end user equipment and the second end user equipment via the relay user equipment; The relay user equipment associates a first PC5 relay radio link control channel with a first end-to-end sidelink data radio bearer to support the inter-user equipment relay communication, wherein the first PC5 relay radio link control channel is established between the relay user equipment and the second end user equipment; The relay user equipment associates a second PC5 relay radio link control channel with a second end-to-end sidelink data radio bearer to support the inter-user equipment relay communication, wherein the second PC5 relay radio link control channel is established between the relay user equipment and the second end user equipment; The relay UE determines to use a second PC5 relay radio link control channel to serve the first end-to-end sidelink data radio bearer and the second end-to-end sidelink data radio bearer; and The relay UE releases the first PC5 relay side link data radio bearer channel in response to determining to use the second PC5 relay radio link control channel to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer.

16. The method according to claim 15, characterized in that After said modification of said second PC5 relay radio link control channel, said second PC5 relay radio link control channel is still associated with said second end-to-end sidelink data radio bearer.

17. The method according to claim 15, characterized in that The second PC5 relay radio link control channel is established based on the first system information to serve the second end-to-end side link data radio bearer, and is determined based on the second system information or preconfiguration to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer, or is derived from the second system information or the preconfiguration to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer, and / or wherein the first / second system information is SIB12.

18. The method according to claim 15, characterized in that The second PC5 relay radio link control channel is established based on pre-configuration to serve the second end-to-end side link data radio bearer, and is determined to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer based on system information, or is derived from the system information to serve the first end-to-end side link data radio bearer and the second end-to-end side link data radio bearer.

19. The method according to claim 15, characterized in that The PC5 connection is a layer 2 link, a unicast link or a PC5 radio resource control connection.

20. The method according to claim 18, wherein The system information is SIB12.

Images