Method and device for relaying user equipment to support connection with another remote user equipment

Abstract

The present invention discloses a method and apparatus for a relay user device to support connection with another user device. The method includes the relay user device establishing a first PC5 unicast link with a first user device and establishing a second PC5 unicast link with a second user device. The method also includes the relay user device forwarding data from the first user device to the second user device. The method also includes the relay user device receiving a link modification request message from the first user device, wherein the link modification request message includes third user information of a third user device. The method also includes the relay user device transmitting a direct communication request message to the third user device, wherein the direct communication request message includes third user information of the third user device. The method also includes the relay user device receiving a direct communication acceptance message from the third user device. The method further includes, in response to receiving the direct communication acceptance message, the relay user device transmitting a link modification acceptance message to the first user device.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communication networks, and more particularly, to methods and apparatus for connecting with another remote UE via a relay UE in a wireless communication system. Background Art

[0002] With the rapidly growing demand for transmitting large amounts of data to and from mobile communication devices, traditional mobile voice communication networks have evolved into networks that use Internet Protocol (IP) packet communications. This IP packet communication can provide IP-based voice, multimedia, multicast, and on-demand communication services to users of mobile communication devices.

[0003] 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 next-generation (e.g., 5G) new radio technologies. Consequently, changes to the current body of 3GPP standards are being submitted and considered to evolve and complete the 3GPP standards. Summary of the Invention

[0004] The present invention discloses a method and apparatus for a relay user equipment (UE) supporting a connection with another UE. In one embodiment, the method includes connecting a first UE to a second UE via the relay UE, wherein a first PC5 unicast link is established between the first UE and the relay UE. The method also includes the first UE transmitting a link modification request message to the relay UE, wherein the link modification request message includes third user information of a third UE. The method further includes the first UE receiving a link modification accept message from the relay UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 A diagram showing a wireless communication system according to an exemplary embodiment is shown.

[0006] 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;

[0007] Figure 3 is a functional block diagram of a communication system according to an exemplary embodiment;

[0008] Figure 4 According to an exemplary embodiment Figure 3 Functional block diagram of the program code;

[0009] Figure 5 It is 3GPP TR 23.752V17.0.0 Figure 6 .8.2.1-1 reappearance;

[0010] Figure 6 It is 3GPP TR 23.752V17.0.0 Figure 6 .8.2.2-1 reappearance;

[0011] Figure 7 It is 3GPP TS 23.287V16.2.0 Figure 5 .2.1.4-1 reappearance;

[0012] Figure 8 It is 3GPP TS 23.287V16.2.0 Figure 6 .3.3.1-1 reappearance;

[0013] Figure 9 It is 3GPP TS 23.287V16.2.0 Figure 6 .3.3.4-1 reappearance;

[0014] Figure 10 It is 3GPP TS 38.836V17.0.0 Figure 5 .1-1 reappearance;

[0015] Figure 11 It is 3GPP TS 38.836V17.0.0 Figure 5 .2-1 reappearance;

[0016] Figure 12 It is 3GPP TS 38.836V17.0.0 Figure 5 .5.1-1 reappearance;

[0017] Figure 13 It is 3GPP TS 38.836V17.0.0 Figure 5 .5.1-2 reappearance;

[0018] Figure 14 It is 3GPP TS 38.331V16.1.0 Figure 5 .8.9.1.1-1 reappearance;

[0019] Figure 15 It is 3GPP TS 38.331V16.1.0 Figure 5 .8.9.1.1-2 reappearance;

[0020] Figure 16 is a diagram according to an exemplary embodiment;

[0021] Figure 17 is an information transfer diagram according to an exemplary embodiment;

[0022] Figure 18 is an information transfer diagram according to an exemplary embodiment;

[0023] Figure 19 is an information transfer diagram according to an exemplary embodiment;

[0024] Figure 20 is a flow chart according to an exemplary embodiment. DETAILED DESCRIPTION

[0025] 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 communication, such as voice, data, and the like. These systems may 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), 3GPP2 Ultra Mobile Broadband (UMB), WiMax, 3GPP New Radio (NR), or some other modulation techniques.

[0026] Specifically, the exemplary wireless communication systems and devices described below may be designed to support one or more standards, such as those provided by a consortium named “3rd Generation Partnership Project”, referred to herein as 3GPP, including: TR 23.752 V17.0.0, “Study of system enhancements for Proximity-based Services (ProSe) in 5G System (5GS) (Release 17)”; TS 23.287 V16.2.0, “Architecture enhancements for 5G System (5GS) to support Vehicle-to-Everything (V2X) services (Release 16)”; TR 38.836 V17.0.0, “Study of NR sidelink relay (Release 17)”; and TS 38.331 V16.4.1, “NR; Radio Resource Control (RRC) Protocol Specification (Release 17)”. The standards and documents listed above are hereby expressly incorporated herein by reference in their entirety.

[0027] Figure 1 A multiple access wireless communication system according to an embodiment of the present invention is shown. An access network 100 (AN) includes multiple antenna groups, one of which includes antennas 104 and 106, another includes antennas 108 and 110, and another includes antennas 112 and 114. Figure 1 In FIG, only two antennas are shown for each antenna group, but each antenna group may utilize more or fewer antennas. Access terminal (AT) 116 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 on forward link 126 and receive information from access terminal (AT) 122 on 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 reverse link 118.

[0028] Each antenna group and / or the area in which it is 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.

[0029] In communications via 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 via a single antenna.

[0030] An access network (AN) may be a fixed station or base station used to communicate 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.

[0031] 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 several data streams is provided from a data source 212 to a transmit (TX) data processor 214.

[0032] 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.

[0033] 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 are then modulated (i.e., symbol mapped) based on the 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 for each data stream may be determined by instructions executed by processor 230.

[0034] 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). TX MIMO processor 220 then provides NT modulation symbol streams to NT transmitters (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.

[0035] Each transmitter 222 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. NT modulated signals from transmitters 222a through 222t are then transmitted from NT antennas 224a through 224t, respectively.

[0036] At receiver system 250, the transmitted modulated signals are received by NR antennas 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.

[0037] An RX data processor 260 then receives and processes the NR received symbol streams from NR receivers 254 based on a particular receiver processing technique to provide NT "detected" symbol streams. 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 RX data processor 260 is complementary to that performed by TX MIMO processor 220 and TX data processor 214 at transmitter system 210.

[0038] 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.

[0039] The reverse link message may include various types of information related to the communication link and / or the received data stream. The reverse link message is then processed by the TX data processor 238, which also receives traffic data for several data streams from the data source 236, modulated by the modulator 280, conditioned by the transmitters 254a through 254r, and transmitted back to the transmitter system 210.

[0040] 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.

[0041] 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, 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 (for example, a keyboard or a keypad), and can output images and sounds through the output device 304 (for example, a monitor or a speaker). The transceiver 314 is used to receive and transmit wireless signals, pass 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 AN100 in.

[0042] Figure 4 According to an embodiment of the present invention Figure 3 . 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 generally performs radio resource control. Layer 2 portion 404 generally performs link control. Layer 1 portion 406 generally performs physical connectivity.

[0043] 3GPP TR 23.752 proposes support for inter-UE relay and related solutions for subsequent releases (e.g., Release 17 / 18) as follows:

[0044] 5.4 Key Issue #4: Support for Inter-UE Relay

[0045] 5.4.1 General description

[0046] This key issue aims to support inter-UE relaying, including support for both in-coverage and out-of-coverage operations.

[0047] Among the possible solutions, at least the following aspects need to be considered:

[0048] - How to (re)select a nearby inter-UE relay UE?

[0049] - Whether and how the network can control inter-UE relay operations, including at least how to:

[0050] - Authorize inter-UE relay, for example, authorize the UE to be an inter-UE relay?

[0051] - Authorize remote UE to access inter-UE relay?

[0052] - Provide visibility of source / target UEs and inter-UE relays to the network for e.g. charging purposes?

[0053] -How to establish a connection between a source UE and a target UE via an inter-UE relay?

[0054] -How to provide an end-to-end QoS framework to meet QoS requirements (e.g., data rate, reliability, latency)?

[0055] -How can the system architecture be enhanced to provide security protection for relay connections?

[0056] - How to provide a mechanism for path change, for example in case of inter-UE relay change?

[0057] NOTE 1: In order to participate in NG-RAN, coordination with the RAN WG is required.

[0058] Note 2: For security aspects, coordination with SA WG3 is required.

[0059] […]

[0060] 6.8 Solution #8: Inter-UE Relay Selection without Relay Discovery

[0061] 6.8.1 Description

[0062] When a source UE wants to communicate with a target UE, it will first attempt to discover the target UE by sending a direct communication request or request message with the target UE information. If the source UE cannot reach the target UE directly, it will attempt to discover an inter-UE relay to reach the target UE, which may also trigger the relay to discover the target UE. To be more efficient, this solution attempts to integrate target UE discovery with inter-UE relay discovery and selection, including two alternatives:

[0063] - Alternative 1: Inter-UE relay discovery and selection may be integrated into the unicast link establishment procedure as described in section 6.3.3 of TS 23.287 [5].

[0064] -Alternative 2: Inter-UE relay discovery and selection are integrated into the Model B direct discovery procedure.

[0065] A new field is proposed to be added to direct communication request or request messages to indicate whether relays can be used for communication. This field may be called relay_indication. When a UE broadcasts a direct communication request or request message, it indicates in the message whether inter-UE relays can be used. For Release 17, the value of this indication is assumed to be limited to a single hop.

[0066] When an inter-UE relay receives a direct communication request or request message with relay_indication set, it should decide whether to forward the message (i.e., modify the message and broadcast it in its vicinity) based on, for example, the relay service code (if present), application ID, authorization policy (e.g., relay for a specific ProSe service), the current traffic load of the relay, the radio conditions between the source UE and the relay UE, etc.

[0067] It may be the case that multiple inter-UE relays can be used to reach the target UE, or the target UE may also receive a direct communication request or request message directly from the source UE. The target UE may select which one to reply to based on, for example, signal strength, local policy (e.g., traffic load on the inter-UE relays), relay service code (if any), or operator policy (e.g., always prefer direct communication or only use some specific inter-UE relays).

[0068] The source UE may receive responses from multiple inter-UE relays and may also receive responses directly from the target UE, with the source UE selecting the communication path based on, for example, signal strength or operator policy (e.g., always preferring direct communication or using only some specific inter-UE relays).

[0069] 6.8.2 Procedure

[0070] 6.8.2.1 Integrating Inter-UE Relay Discovery and Selection into Unicast Link Establishment Procedure (Alternative 1)

[0071] [3GPP TR 23.752 V17.0.0 is titled “5G ProSe Inter-UE Relay Selection (Alternative 1) (5G ProSe

[0072] UE-to-UE relay selection(Alternative 1))” Figure 6 .8.2.1-1 Reproduced as Figure 5]

[0073] Figure 6 .8.2.1-1Describe the procedures for the proposed method.

[0074] 0. Authorize the UE to use services provided by the inter-UE relay. The inter-UE relay is authorized to provide services that relay services between UEs. Authorization and parameter provisioning can use solutions in KI#8, such as Sol#36. Authorization can occur when the UE / relay registers with the network. Security-related parameters can be provisioned so that the UE and relay can verify authorization with each other, if necessary.

[0075] 1. UE-1 wishes to establish unicast communication with UE-2, either via a direct link with UE-2 or via an inter-UE relay. UE-1 then broadcasts a direct communication request with relay_indication enabled. The message will be received by both relay-1 and relay-2. If UE-2 is nearby, the message will also be received by UE-2. UE-1 includes source UE information, target UE information, application ID, and relay service code (if any). If UE-1 does not wish to involve a relay in the communication, it will disable relay_indication.

[0076] NOTE 1: The data type of relay_indication may be determined in Phase 3. The details of the direct communication request / accept message will be determined in Phase 3.

[0077] 2. Relay-1 and Relay-2 decide to participate in the procedure. They broadcast a new Direct Communication Request message in their vicinity without enabling relay_indication. If a relay receives this message, it simply discards it. When a relay broadcasts a Direct Communication Request message, it includes source UE information, target UE information, and relay UE information (e.g., relay UE ID) in the message, using the relay's L2 address as the source Layer 2 ID. The relay maintains the association between the source UE information (e.g., source UE L2 ID) and the new Direct Communication Request.

[0078] 3. UE-2 receives direct communication request messages from Relay-1 and Relay-2. If UE-2 is within the communication range of UE-1, UE-2 may also directly receive a direct communication request message from UE-1.

[0079] 4. UE-2 selects Relay-1 and responds with a Direct Communication Accept message. If UE-2 receives a Direct Communication Request directly from UE-1, it can choose to set up a direct communication link by sending a Direct Communication Accept message directly to UE-1. After receiving the Direct Communication Accept message, the Inter-UE Relay retrieves the source UE information stored in step 2 and sends a Direct Communication Accept message to the source UE with the relay UE information appended to the message.

[0080] After step 4, UE-1 and UE-2 respectively establish a PC5 link with the selected inter-UE relay.

[0081] NOTE 2: Security establishment between UE1 and Relay-1, and between Relay-1 and UE-2, is performed before Relay-1 and UE-2 send the Direct Communication Accept message. The details of the authentication / security establishment procedure are determined by SA WG3. If a PC5 link already exists between the source (or target) UE and a relay that can be used for relay services, the security establishment procedure can be skipped.

[0082] 5. UE-1 receives a Direct Communication Accept message from Relay-1. UE-1 selects a path based on, for example, policy (e.g., always select a direct path when possible), signal strength, etc. If UE-1 receives a Direct Communication Accept / Response message requesting acceptance directly from UE-2, it may choose to set up a direct PC5 L2 link with UE-2, as described in Section 6.3.3 of TS 23.287 [5], and skip step 6.

[0083] 6a. For the L3 inter-UE relay scenario, UE-1 and UE-2 complete the establishment of a communication link via the selected inter-UE relay. The link setup information may vary depending on the type of relay (e.g., L2 or L3 relay). UE-1 and UE-2 may then communicate via the relay. Regarding the IP address assignment of the source / remote UE, the address may be allocated by the relay or by the UE itself (e.g., a link-local IP address), as defined in Section 6.3.3 of TS 23.287 [5].

[0084] 6b. For the Layer 2 inter-UE relay scenario, the source UE and target UE can establish an end-to-end PC5 link via a relay. UE-1 sends a unicast E2E Direct Communication Request message to UE-2 via Relay-1, and UE-2 responds with a unicast E2E Direct Communication Request message to UE-1 via Relay-1. Relay-1 delivers the message based on the identity information of UE-1 / UE-2 in the adaptation layer.

[0085] NOTE 3: How Relay-1 can deliver messages based on the identity information of UE-1 / UE-2 in the Adaptation Layer requires collaboration with RAN2 during the normative phase.

[0086] Note 4: For relay or path selection, the source UE may set a timer after issuing a direct communication request to collect corresponding response messages before making a decision. Similarly, the target UE may also set a timer after receiving the first copy of the direct communication request / message to collect multiple copies of the message from different paths before making a decision.

[0087] Note 5: When a UE first receives a message from an inter-UE relay, it needs to verify that the relay is authorized to act as an inter-UE relay. Similarly, an inter-UE relay may also need to verify that the UE is authorized to use the relay service. The details of this verification and how to ensure communication between two UEs via an inter-UE relay will be defined by SA WG3.

[0088] 6.8.2.2 Integration of Inter-UE Relay Discovery and Selection into Model B Direct Discovery Procedure (Alternative 2)

[0089] Figure 6 .8.2.2-1 describes the procedures for inter-UE relay discovery model B, and the discovery / selection procedures are separated from the hop-by-hop and end-to-end link establishment.

[0090] [3GPP TR 23.752 V17.0.0 is titled “5G ProSe Inter-UE Relay Selection (Alternative 2) (5G ProSe

[0091] UE-to-UE relay selection(Alternative 2))” Figure 6 .8.2.2-1 Reproduced as Figure 6 ]

[0092] 1. UE-1 broadcasts a discovery request message carrying UE-1 information, target UE information (UE-2), application ID, and relay service code (if any). UE-1 may also indicate that relay_indication is enabled.

[0093] 2. Upon receiving the discovery request, the candidate relay UE-R broadcasts a discovery request carrying UE-1 information, UE-R information, and target UE information. The relay UE-R uses the relay's L2 address as the source layer 2 ID.

[0094] 3. Target UE-2 responds to the discovery message. If UE-2 received a discovery request message in step 1, then in step 3b, UE-2 responds with a discovery response message using UE-1 information and UE-2 information. If UE-2 did not receive a discovery request message in step 2, then in step 3a, UE-2 responds with a discovery response message using UE-1 information, UE-R information, and UE-2 information.

[0095] 4. Upon receiving the discovery response in step 3a, UE-R sends a discovery response with UE-1 information, UE-R information, and UE-2 information. If more than one candidate relay UE responds to the discovery response message, UE-1 may select a relay UE based on, for example, implementation or link qualifications.

[0096] 5. The source UE and target UE may need to establish a PC5 link with the relay before communicating with each other. If a PC5 link already exists between UE-1 (which can be used for relay) and UE-R, step 5a can be skipped. If a PC5 link already exists between UE-2 (which can be used for relay) and UE-R, step 5b can be skipped.

[0097] 6a. Same as step 6a described in Section 6.8.2.1.

[0098] 6b. For Layer 2 inter-UE relay, an E2E unicast direct communication request message is sent from UE1 to the selected relay via the per-hop link (established in step 5a) and the adaptation layer information identifying the peer UE (UE3) as the destination. The inter-UE relay delivers the E2E message based on the peer UE's identity information in the adaptation layer. The initiator (UE1) knows the adaptation layer information identifying the peer UE (UE3) after the discovery procedure. UE3 responds in the same manner with an E2E unicast direct communication accept message.

[0099] NOTE 1: For the Layer 2 inter-UE relay case, whether step 5b is performed before step 6b or triggered during step 6b will be decided at the normative stage.

[0100] NOTE 2: How Relay-1 can deliver messages based on the identity information of UE-1 / UE-2 in the Adaptation Layer requires collaboration with RAN2 during the normative phase.

[0101] 6.8.3 Impact on Services, Entities, and Interfaces

[0102] Impact on UEs supporting new relay-related functions.

[0103] 3GPP TS 23.287 specifies unicast mode V2X communication over the PC5 reference point, Layer 2 link establishment, link identifier update, and Layer 2 link modification over the PC5 reference point as follows:

[0104] 5.2.1.4 Unicast mode communication over the PC5 reference point

[0105] The NR-based PC5 reference point only supports unicast communication mode. Figure 5 .2.1.4-1 shows an example of a PC5 unicast link.

[0106] [3GPP TS 23.287 V16.2.0 entitled "Example of PC5 Unicast Links" Figure 5 .2.1.4-1 Reproduced as Figure 7 ]

[0107] When V2X communication is conducted over a PC5 unicast link, the following principles apply:

[0108] A PC5 unicast link between two UEs allows V2X communication between one or more pairs of peer V2X services in these UEs. All V2X services in the UE using the same PC5 unicast link use the same application layer ID.

[0109] NOTE 1: Due to privacy reasons, the application layer ID may change over time, as described in clauses 5.6.1.1 and 6.3.3.2. This does not cause the re-establishment of the PC5 unicast link. The UE triggers the link identifier update procedure as specified in clause 6.3.3.2.

[0110] - A PC5 unicast link supports one or more V2X service types (e.g., PSID or ITS-AID) if these V2X service types are associated with at least one peer application layer ID pair for this PC5 unicast link. Figure 5 As shown in .2.1.4-1, UE A and UE B have two PC5 unicast links, one between peer application layer ID 1 / UE A and application layer ID 2 / UE B and one between peer application layer ID 3 / UE A and application layer ID 4 / UE B.

[0111] NOTE 2: The source UE is not required to know whether different target application layer IDs on different PC5 unicast links belong to the same target UE.

[0112] - PC5 unicast links use a single network layer protocol such as IP or non-IP to support V2X communications.

[0113] - PC5 unicast links support a per-flow QoS model as specified in Section 5.4.1.

[0114] When the application layer in the UE initiates data transfer for a V2X service that requires unicast communication mode over the PC5 reference point:

[0115] - If the pair of peer application layer IDs and network layer protocol of this PC5 unicast link are the same as those required by the application layer in the UE for this V2X service, then the UE shall reuse the existing PC5 unicast link and modify the existing PC5 unicast link as specified in Section 6.3.3.4 to add this V2X service; otherwise

[0116] - The UE shall trigger the establishment of a new PC5 unicast link as specified in Section 6.3.3.1.

[0117] After successfully establishing the PC5 unicast link, UE A and UE B use the same pair of Layer 2 IDs for subsequent PC5-S signaling message exchanges and V2X service data transmission, as specified in Section 5.6.1.4. The V2X layer of the transmitting UE indicates to the AS layer whether the transmission is for PC5-S signaling messages (i.e., direct communication request / accept, link identifier update request / response, disconnect request / response, link modification request / accept) or V2X service data.

[0118] For each PC5 unicast link, the UE assigns a different PC5 link identifier that uniquely identifies the PC5 unicast link in the UE during the lifetime of the PC5 unicast link. Each PC5 unicast link is associated with a unicast link profile, which includes:

[0119] - V2X service type (e.g., PSID or ITS-AID); and

[0120] - UE A's Application Layer ID and Layer 2 ID; and

[0121] - UE B's Application Layer ID and Layer 2 ID; and

[0122] - Network layer protocols used over PC5 unicast links; and

[0123] - For each V2X service type, a set of PC5 QoS Flow Identifiers (PFIs). Each PFI is associated with a QoS parameter (i.e., PQI).

[0124] For privacy reasons, the Application Layer ID and Layer 2 ID may change during the lifetime of a PC5 unicast link as described in Sections 5.6.1.1 and 6.3.3.2, and if so, the unicast link profile should be updated accordingly. The UE uses the PC5 link identifier to indicate the PC5 unicast link to the V2X application layer, so the V2X application layer identifies the corresponding PC5 unicast link even if there is more than one unicast link associated with one V2X service type (e.g., the UE establishes multiple unicast links with multiple UEs for the same V2X service type).

[0125] Following a Layer 2 link modification of an established PC5 unicast link as specified in clause 6.3.3.4 or a Layer 2 link identifier update as specified in clause 6.3.3.2, the unicast link configuration file shall be updated accordingly.

[0126] V2X service information and QoS information are carried in PC5-S signaling messages and exchanged between two UEs as specified in Section 6.3.3. Based on the replacement information, the PFI is used to identify the V2X service. When a receiving UE receives V2X service data over an established PC5 unicast link, it determines the appropriate V2X service based on the PFI and forwards the received V2X service data to higher layers.

[0127] After receiving an indication from the AS layer to release the PC5-RRC connection due to RLF, the V2X layer in the UE locally releases the PC5 unicast link associated with this PC5-RRC connection. The AS layer uses the PC5 link identifier to indicate the release of the PC5 unicast link of the PC5-RRC connection.

[0128] When the PC5 unicast link is released as specified in Section 6.3.3.3, the V2X layer of each UE for the PC5 unicast link notifies the AS layer that the PC5 unicast link has been released. The V2X layer uses the PC5 link identifier to indicate the released unicast link.

[0129] […]

[0130] 5.6.1.4 Identifier for unicast mode V2X communication over the PC5 reference point

[0131] For unicast mode V2X communications over the PC5 reference point, the destination Layer 2 ID used depends on the communicating peer. The Layer 2 ID of the communicating peer, identified by the Application Layer ID, may be discovered during establishment of the PC5 unicast link, or known to the UE via previous V2X communications (e.g., an existing or previous unicast link to the same Application Layer ID), or obtained from an Application Layer Service Notification. The initial signaling for establishing the PC5 unicast link may use a preset destination Layer 2 ID associated with the V2X service type (e.g., PSID / ITS-AID) configured for the PC5 unicast link establishment, as specified in Section 5.1.2.1. During the PC5 unicast link establishment procedure, the Layer 2 IDs will be exchanged and shall be used for future communications between the two UEs, as specified in Section 6.3.3.1.

[0132] An application layer ID is associated with one or more V2X applications within a UE. If a UE has more than one application layer ID, each application layer ID of the same UE may be considered an application layer ID of a different UE from the perspective of a peer UE.

[0133] Since the V2X application layer does not use Layer 2 IDs, the UE maintains a mapping between the application layer ID and the source Layer 2 ID used for the PC5 unicast link. This allows the source Layer 2 ID to be changed without disrupting the V2X application.

[0134] When the application layer ID changes, the source layer 2 ID of the PC5 unicast link should change if the link is used for V2X communication with the changed application layer ID.

[0135] Based on the privacy configuration as specified in section 5.1.2.1, updating the new identifier of the source UE to the peer UE for the established unicast link may result in the peer UE changing its Layer 2 ID and optionally IP address / prefix (if IP communication is used as defined in section 6.3.3.2).

[0136] A UE may establish multiple PC5 unicast links with a peer UE and use the same or different source layer 2 IDs for these PC5 unicast links.

[0137] […]

[0138] 6.3.3.1 Establishing a Layer 2 link via the PC5 reference point

[0139] To perform unicast mode V2X communication over the PC5 reference point, the UE is configured with relevant information as described in Section 5.1.2.1.

[0140] Figure 6 .3.3.1-1 shows the Layer 2 link establishment procedure for unicast mode V2X communication over the PC5 reference point.

[0141] [3GPP TS 23.287 V16.2.0 entitled "Layer-2 link establishment procedure" Figure 6 .3.3.1-1 Reproduced as Figure 8 ]

[0142] 1. The UE determines the destination Layer 2 ID for signaling reception for PC5 unicast link establishment as specified in Section 5.6.1.4. The destination Layer 2 ID is configured with the UE as specified in Section 5.1.2.1.

[0143] 2. The V2X application layer in UE-1 provides application information for PC5 unicast communication. The application information includes the V2X service type of the V2X application (e.g., PSID or ITS-AID) and the application layer ID of the initiating UE. The application information may also include the application layer ID of the target UE.

[0144] The V2X application layer in UE-1 may provide the V2X application requirements for this unicast communication. As specified in Section 5.4.1.4, UE-1 determines the PC5 QoS parameters and PFI.

[0145] If UE-1 decides to reuse the existing PC5 unicast link as specified in section 5.2.1.4, the UE triggers the Layer 2 Link Modification procedure as specified in section 6.3.3.4.

[0146] 3. UE-1 sends a direct communication request message to initiate the unicast layer 2 link establishment process. The direct communication request message contains:

[0147] - Source user information: the application layer ID of the originating UE (ie, the application layer ID of UE-1).

[0148] - If the V2X application layer provides the target UE’s application layer ID in step 2, the following information is included:

[0149] - Target user information: the application layer ID of the target UE (ie, the application layer ID of UE-2).

[0150] - V2X service information: Information about the V2X service requesting Layer 2 link establishment (e.g., PSID or ITS-AID).

[0151] - Security information: information used to establish security.

[0152] NOTE 1 Security information and the necessary protection of source and destination user information are defined by SA WG3.

[0153] As specified in Sections 5.6.1.1 and 5.6.1.4, the source Layer 2 ID and destination Layer 2 ID used to send the Direct Communication Request message are determined. 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.

[0154] 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.

[0155] 4. Establish security for UE-1 as follows:

[0156] 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.

[0157] 4b. If the target user information is not included in the direct communication request message, the UE interested in using the announced V2X service via the PC5 unicast link with UE-1 responds by establishing security with UE-1.

[0158] NOTE 2: The signalling used for security procedures is defined by SA WG3.

[0159] When security protection is enabled, UE-1 sends the following information to the target UE:

[0160] - If using IP communication:

[0161] -IP Address Configuration: For IP communication, this link requires IP address configuration, and IP address configuration indicates one of the following values:

[0162] - "IPv6 router", if only the IPv6 address allocation mechanism is supported by the originating UE, i.e. acting as an IPv6 router; or

[0163] - "IPv6 address allocation not supported" if the IPv6 address allocation mechanism is not supported by the originating UE.

[0164] - Link-local IPv6 address: A link-local IPv6 address formed locally based on RFC 4862

[21] if UE-1 does not support the IPv6 IP address allocation mechanism, i.e., the IP address configuration indicates "IPv6 address allocation is not supported".

[0165] -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.).

[0166] As specified in Sections 5.6.1.1 and 5.6.1.4, 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.

[0167] 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.

[0168] 5. The target UE, which has successfully established security with UE-1, sends a direct communication acceptance message to UE-1:

[0169] 5a. (Layer 2 Link Establishment towards UE) If the Direct Communication Request message contains target user information, and if the application layer ID for UE-2 matches, the target UE, ie, UE-2, responds with a Direct Communication Accept message.

[0170] 5b. (Layer 2 Link Establishment for V2X Services) If the Direct Communication Request message does not contain target user information, the UE interested in using the notified V2X service responds to the request by sending a Direct Communication Accept message (in the Figure 6 .UE-2 and UE-4 in 3.3.1-1).

[0171] The direct communication acceptance message includes:

[0172] -Source user information: the application layer ID of the UE that sends the direct communication accept message.

[0173] - QoS information: Information about PC5 QoS flows. For each PC5 QoS flow, the PFI requested by UE-1 and the corresponding PC5 QoS parameters (ie, PQI and conditionally other parameters, such as MFBR / GFBR, etc.).

[0174] - If using IP communication:

[0175] -IP Address Configuration: For IP communication, this link requires IP address configuration, and IP address configuration indicates one of the following values:

[0176] - "IPv6 router", if the IPv6 address allocation mechanism is supported by the target UE, i.e. act as an IPv6 router; or

[0177] - "IPv6 address allocation not supported" if the IPv6 address allocation mechanism is not supported by the target UE.

[0178] - Link-local IPv6 address: A link-local IPv6 address formed locally based on RFC 4862

[21] . If the target UE does not support the IPv6 IP address allocation mechanism, i.e., the IP address configuration indicates "IPv6 address allocation is not supported", and UE-1 includes a link-local IPv6 address in the Direct Communication Request message, the target UE shall include a non-conflicting link-local IPv6 address.

[0179] If both UEs (ie, the initiating UE and the target UE) are selected to use link-local IPv6 addresses, they shall disable dual address detection as defined in RFC 4862

[21] .

[0180] NOTE 3: When the initiating UE or target UE indicates support for IPv6 routers, the corresponding address configuration procedure shall be implemented after the Layer 2 link is established and the link-local IPv6 address shall be ignored.

[0181] The V2X 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.

[0182] 6. Transmit V2X service data via the established unicast link as follows:

[0183] Provide the PC5 link identifier and PFI as well as V2X service data to the AS layer.

[0184] Optionally additionally, layer 2 ID information (ie, source layer 2 ID and destination layer 2 ID) is provided to the AS layer.

[0185] NOTE 4: It is up to the UE implementation to provide the Layer 2 ID information to the AS layer.

[0186] UE-1 sends V2X service data using a source layer 2 ID (i.e., the layer 2 ID of UE-1 for this unicast link) and a destination layer 2 ID (i.e., the layer 2 ID of the peer UE for this unicast link).

[0187] NOTE 5: The PC5 unicast link is bidirectional, so UE-1’s peer UE can send V2X service data to UE-1 via the unicast link with UE-1.

[0188] […]

[0189] 6.3.3.4 Layer 2 Link Modification for Unicast Links

[0190] Figure 6 .3.3.4-1 shows the Layer 2 link modification procedure for unicast links. This procedure is used to:

[0191] -Add new V2X services to existing PC5 unicast links.

[0192] -Remove V2X services from existing PC5 unicast links.

[0193] -Add new PC5 QoS flow in existing PC5 unicast link.

[0194] - Modify an existing PC5 QoS flow in an existing PC5 unicast link.

[0195] - Remove existing PC5 QoS flows in existing PC5 unicast links.

[0196] [3GPP TS 23.287 V16.2.0 entitled "Layer-2 link modification procedure" Figure 6 .3.3.4-1 Reproduced as Figure 9 ]

[0197] 0. UE-1 and UE-2 have a unicast link established as described in Section 6.3.3.1.

[0198] 1. The V2X application layer in UE-1 provides application information for PC5 unicast communication. The application information includes the V2X service type of the V2X application (e.g., PSID or ITS-AID) 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 Section 5.2.1.4 and therefore decides to modify the unicast link established with UE-2, UE-1 sends a link modification request to UE-2.

[0199] The link modification request message contains:

[0200] a) To add new V2X services to an existing PC5 unicast link:

[0201] - V2X service information: Information about the V2X service to be added (eg, PSID or ITS-AID).

[0202] -QoS information: Information about the PC5 QoS flow for each V2X service to be added. For each PC5 QoS flow, PFI and corresponding PC5 QoS parameters (i.e., PQI and conditionally other parameters such as MFBR / GFBR, etc.)

[0203] b) Remove V2X services from the existing PC5 unicast link:

[0204] - V2X service information: Information about the V2X service to be removed (eg, PSID or ITS-AID).

[0205] c) Add a new PC5 QoS flow to an existing PC5 unicast link:

[0206] - V2X service information: Information about the V2X service that requires adding a new QoS flow (e.g., PSID or ITS-AID).

[0207] - QoS information: Information about the PC5 QoS flow to be modified. For each PC5 QoS flow, PFI and corresponding PC5 QoS parameters (ie, PQI and conditionally other parameters, such as MFBR / GFBR, etc.).

[0208] d) To modify a PC5 QoS flow in an existing PC5 unicast link:

[0209] - QoS information: Information about the PC5 QoS flow to be modified. For each PC5 QoS flow, PFI and corresponding PC5 QoS parameters (ie, PQI and conditionally other parameters, such as MFBR / GFBR, etc.).

[0210] e) To remove the PC5 QoS flow from an existing PC5 unicast link:

[0211] -PFI.

[0212] 2. UE-2 responds with a Link Modification Accept message.

[0213] The link modification acceptance message contains:

[0214] - For cases a), c) and d) described in step 1:

[0215] -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.).

[0216] The V2X 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.

[0217] 3GPP TS 38.836 specifies the following for sidelink-based UE relay:

[0218] 5. Inter-UE Relay Based on Sidelink

[0219] 5.1 Scenarios, Assumptions, and Requirements

[0220] Inter-UE relaying enables coverage extension and power savings for sidelink transmissions between two sidelink UEs. The coverage scenarios considered in this study are as follows:

[0221] 1) All UEs (source UE, relay UE, destination UE) are within coverage.

[0222] 2) All UEs (source UE, relay UE, destination UE) are out of coverage.

[0223] 3) Partial coverage, where at least one of the UEs involved in the relay (source UE, relay UE, destination UE) is within the coverage, and at least one of the UEs involved in the relay is out of coverage.

[0224] RAN2 strives to find a common solution for both in- and out-of-coverage situations. For inter-UE relay, the scenario where the UE can be in the coverage of different cells is supported.

[0225] Figure 5 .1-1 shows the scenario considered for inter-UE relay. Figure 5 In .1-1, coverage means that the source / destination UE and / or inter-UE relay UE are within the coverage and can access the network on Uu.

[0226] [3GPP TS 38.836 V17.0.0 entitled "Scenarios for UE-to-UE Relay (where the coverage status is not shown)" Figure 5 .1-1 reproduced as Figure 10 ]

[0227] PC5 assumes NR side link between remote UE and inter-UE relay.

[0228] Cross-RAT configuration / control of source UE, inter-UE relay, and destination UE is not considered, i.e., the eNB / ng-eNB does not control / configure the NR source UE, target UE, or inter-UE relay UE. For inter-UE relay, this study focuses on unicast data traffic between the source UE and the destination UE.

[0229] Configuring / scheduling a UE (source UE, destination UE, or inter-UE relay UE) by an SN to perform NR sidelink communication is out of the scope of this study.

[0230] For inter-UE relaying, it is assumed that a remote UE has an active end-to-end connection via only a single relay UE at a given time.

[0231] Once the PC5 link is established between the source UE, the inter-UE relay, and the destination UE, data relay between the source UE and the destination UE may occur.

[0232] No restrictions are assumed regarding the RRC state of any UE involved in inter-UE relay.

[0233] During this release of mobility, the requirement for service continuity is only for UE-to-network relaying, not for inter-UE relaying.

[0234] 5.2 Discovery

[0235] Model A and Model B discovery models as defined in Section 5.3.1.2 of TS 23.303 [3] are supported for inter-UE relay and integrated PC5 unicast link establishment procedures may be supported based on SA2 conclusions. Figure 5 The protocol stack for discovery messages is described in .2-1. [3GPP TS 38.836 V17.0.0, titled "Protocol Stack of Discovery Message for UE-to-UE Relay" Figure 5 .2-1 reappears as Figure 11 ]

[0236] When triggered by upper layers, a relay UE or a remote UE is allowed to transmit a discovery message.

[0237] Both remote UE and relay UE may rely on pre-configuration unless the relevant radio configuration is provided by the network via system information or dedicated signaling.

[0238] The resource pool for transmitting discovery messages may be shared with or separate from the resource pool for data transmission.

[0239] - For shared resource pools and separate resource pools, new LCIDs are introduced for discovery messages, ie, discovery messages are carried by new SL SRBs.

[0240] - Within separate resource pools, discovery messages are processed equally to each other during the LCP procedure.

[0241] 5.3 Relay Selection (Reselection) Criteria and Procedures

[0242] The baseline solution for relay selection (reselection) is as follows:

[0243] Radio measurements at the PC5 interface are considered as part of the (re)selection criteria for the relay.

[0244] - The remote UE uses at least the radio signal strength measurements of the sidelink discovery messages to assess whether the PC5 link quality of the relay UE meets the relay selection and reselection criteria.

[0245] - When a remote UE is connected to a relay UE, it may use SL-RSRP measurements on the sidelink unicast link to assess whether the PC5 link quality of the relay UE meets the relay reselection criteria.

[0246] Further details regarding PC5 radio measurement criteria, such as when there is no transmission on the sidelink unicast link, may be discussed in the WI phase. If the remote UE has a PC5-RRC connection with the relay UE, how to perform RSRP measurements based on RSRP from discovery messages and / or SL-RSRP may be determined in the WI phase.

[0247] For relay selection (or reselection), the remote UE compares the relay UE's PC5 radio measurements against thresholds configured or pre-configured by the gNB. The remote UE also needs to consider higher-layer criteria for relay selection (or reselection), but the details are left to SA2. Relay selection (or reselection) can be triggered by upper layers of the remote UE.

[0248] If the NR sidelink signal strength of the current sidelink relay falls below a (pre-)configured threshold, relay reselection should be triggered. Also, if the remote UE detects RLF of the PC5 link with the current relay UE, relay reselection may be triggered.

[0249] The above baseline for relay selection (reselection) is applicable to both L2 and L3 relay solutions.Additional AS layer criteria may be considered in the WI phase for both L2 and L3 inter-UE relay solutions.

[0250] For relay selection (reselection), when the remote UE has multiple suitable relay UE candidates that meet all AS layer and higher layer criteria and the remote UE needs to select a relay UE by itself, it is up to the UE implementation to decide which relay UE to select.

[0251] As captured in TR 23.752, Solution #8 and Solution #50 in TR 23.752 are considered as baseline solutions for L2 and L3 inter-UE relay reselection, and Solution #8 and Solution #11 in TR 23.752 are considered as baseline solutions for L3 inter-UE relay selection.

[0252] 5.4 Relay / Remote UE Authorization

[0253] RAN2 concludes that the authorization of both the relay UE and the remote UE has no RAN2 impact.

[0254] 5.5 Layer 2 Relay

[0255] 5.5.1 Architecture and Protocol Stack

[0256] For L2 inter-UE relay architecture, the protocol stack is similar to L2UE to network relay except for the fact that the termination points are two remote UEs. The protocol stacks for user plane and control plane for L2 inter-UE relay architecture are described in Figure 5 .5.1-1 and Figure 5 .Described in 5.1-2.

[0257] An adaptation layer is supported on the second PC5 link (i.e., the PC5 link between the relay UE and the destination UE) for L2 inter-UE relaying. For L2 inter-UE relaying, the adaptation layer is placed above the RLC sublayer for CP and UP on the second PC5 link. Sidelink SDAP / PDCP and RRC terminate between the two remote UEs, while RLC, MAC, and PHY terminate within each PC5 link.

[0258] [3GPP TS 38.836 V17.0.0, entitled "User plane protocol stack for L2 inter-UE relay"

[0259] protocol stack for L2 UE-to-UE Relay)" Figure 5 .5.1-1 reproduced as Figure 12 ]

[0260] [3GPP TS 38.836 V17.0.0, titled "Control plane protocol stack for L2 UE-to-UE Relay" Figure 5 .5.1-2 reproduced as Figure 13 ]

[0261] For the first hop of L2 inter-UE relay:

[0262] - The first hop PC5 adaptation layer supports N:1 mapping between the remote UE SL radio bearer and the first hop PC5 RLC channel for relaying.

[0263] - The adaptation layer on the first PC5 hop between the source remote UE and the relay UE supports identifying traffic destined for different destination remote UEs.

[0264] For the second hop of L2 inter-UE relay:

[0265] - The second hop PC5 adaptation layer may be used to support bearer mapping between the incoming RLC channel on the first PC5 hop and the outgoing RLC channel on the second PC5 hop at the relay UE.

[0266] - The PC5 adaptation layer supports N:1 bearer mapping between multiple incoming PC5 RLC channels on the first PC5 hop and one outgoing PC5 RLC channel on the second PC5 hop, and supports remote UE identification functionality.

[0267] For L2 inter-UE relay:

[0268] - Identity information of the remote UE end-to-end radio bearers is contained in the adaptation layer in the first and second PC5 hops.

[0269] - In addition, the identity information of the source remote UE and / or the identity information of the destination remote UE are candidate information to be included in the adaptation layer, which will be decided in the WI stage.

[0270] 5.5.2QoS

[0271] The QoS handling for L2 inter-UE relay is influenced by upper layers, such as solution #31 in TR 23.752 studied by SA2.

[0272] 5.5.3 Security

[0273] As described in Section 6.9.1.2 (Solution #9) of TR 23.752, in the case of L2 inter-UE relay, security is established at the PDCP layer in an end-to-end manner between UE1 and UE2. The security aspect requires confirmation by SA3.

[0274] 5.5.4 Control Plane Programs

[0275] RAN2 considers the SA2 solution in TR 23.752 [6] as the baseline. Other RAN2 impacts (if any) can be discussed in the WI phase.

[0276] 3GPP TS 38.331 specifies the sidelink RRC reconfiguration for NR sidelink communications as follows:

[0277] 5.8.9.1 Sidelink RRC Reconfiguration

[0278] 5.8.9.1.1 Overview [3GPP TS 38.331 V16.1.0, entitled "Sidelink RRC reconfiguration successful (Sidelink RRC reconfiguration,

[0279] successful) Figure 5 .8.9.1.1-1 reproduced as Figure 14 ]

[0280] [3GPP TS 38.331 V16.1.0, entitled "Sidelink RRC reconfiguration failure (Sidelink RRCreconfiguration,

[0281] failure) Figure 5 .8.9.1.1-2 reproduced as Figure 15 ]

[0282] The purpose of this procedure is to modify the PC5-RRC connection, such as establishing / modifying / releasing sidelink DRBs, configuring NR sidelink measurements and reporting, configuring sidelink CSI reference signal resources and CSI reporting latency bounds.

[0283] In the following cases, the UE may initiate the sidelink RRC reconfiguration procedure and perform the operations in subclause 5.8.9.1.2 on the corresponding PC5-RRC connection:

[0284] - Release the sidelink DRB associated with the peer UE as specified in subclause 5.8.9.1a.1;

[0285] - Establishing a sidelink DRB associated with the peer UE as specified in subclause 5.8.9.1a.2;

[0286] - Modify the parameters contained in the SLRB-Config of the sidelink DRB associated with the peer UE, as specified in section 5.8.9.1.5a.2;

[0287] - Configuration of peer UE to perform NR sidelink measurements and reporting.

[0288] -Configuration of sidelink CSI reference signal resources and CSI reporting delay bound.

[0289] 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.

[0290] Key issue #4 in 3GPP TR 23.752 describes support for inter-UE relay in the next release (i.e., Release 17 / 18), which means that relay can be used to support communication between two UEs in the case where the two UEs cannot communicate with each other directly. Presumably, the inter-UE relay needs to establish a PC5 unicast link with each of the source UE (i.e., the first PC5 hop) and the target UE (i.e., the second PC5 hop), so that the integrated PC5 unicast link between the source UE and the target UE can support related ProSe services, such as Figure 16 As shown in .

[0291] 3GPP TS 38.836 Figure 5 .5.1-1 (reproduced as Figure 12 )and Figure 5 .5.1-2 (reproduced as Figure 13) describes the user plane and control plane protocol stacks of the L2 inter-UE relay architecture, including an adaptation layer to support multiple source UEs communicating with a single target UE via an inter-UE relay, and a single source UE communicating with multiple target UEs via an inter-UE relay. 3GPP TS 38.836 further specifies that the header of the adaptation layer protocol data unit (PDU) for the first and second PC5 hops includes the identity information of the (remote UE) end-to-end radio bearer. Additionally, the identity information of the source remote UE and / or the identity information of the destination remote UE are candidates for inclusion in the header of the adaptation layer PDU, which will be determined during the subsequent WI phase.

[0292] Presumably, when transmitting an adaptation layer PDU, the source UE may need to include information (e.g., the target UE's local identity / identifier (ID)) in the PDU's header to identify the target UE, so that the inter-UE relay can forward the service data unit (SDU) contained in the PDU to the target UE on the right-link Radio Link Control (RLC) bearer (or logical channel) in the second PC5 hop, because separate sidelink RLC bearers can be established between the inter-UE relay and different target UEs for communication. In addition to the target UE's identity information, the end-to-end radio bearer ID included in the header by the source UE can also be used by the inter-UE relay to determine the sidelink RLC bearer. The header may not need to include information identifying the source UE. On the other hand, the inter-UE relay may need to include information (e.g., the local ID of the source UE) to identify the source UE in the header of the adaptation layer PDU sent to the target UE, so that the target UE can deliver the PDU contained in the PDU to the right link PDCP entity, because separate sidelink PDCP entities are established in the target UE for different source UEs. The end-to-end radio bearer ID can also be included in the header of the adaptation layer PDU through the inter-UE relay. The header may not need to include information identifying the target UE. Figure 17 Examples illustrating the above concepts.

[0293] To satisfy the above concepts, a remote UE needs to know the local ID of the other remote UE for the adaptation layer when communicating with the other remote UE via the inter-UE relay, and the inter-UE relay needs to know the local IDs of both remote UEs. It seems that the remote UE does not need to know its own local ID. In addition, each local ID of the other remote UEs associated with the relevant remote UE can be unique within the scope of the relevant remote UE. It is also possible that each local ID of the remote UE can be unique within the scope of the inter-UE relay. Since the inter-UE relay needs to know the local IDs of the two paired remote UEs, a possible solution is for the inter-UE relay to assign or allocate a local ID to each remote UE and then provide the local ID of one remote UE to the other remote UE. Alternatively, one remote UE can assign or allocate a local ID to the other remote UE and then provide it to the inter-UE relay. In this case, the inter-UE relay needs to maintain the associated local ID of each remote UE.

[0294] Essentially, each remote UE can maintain a UE context for another remote UE communicating with it via an inter-UE relay to support relay operations. The UE context can include an upper-layer ID (e.g., the UE's application layer ID), a local ID, and an application / service ID. In other words, an association between an upper-layer ID and a local ID is maintained in each remote UE to support relay operations. The inter-UE relay can also maintain a UE context for each remote UE. In addition to an upper-layer ID (e.g., the UE's application layer ID), a local ID, and an application / service ID, the UE context in the inter-UE relay can also include a Layer 2 ID for the associated remote UE. The UE's upper-layer ID can be the UE's application layer ID, not a Layer 2 ID.

[0295] For a possible solution, the inter-UE relay may assign or allocate a local ID for each remote UE, and then provide the local ID of one remote UE to the other remote UE during an integrated unicast link establishment procedure with two paired remote UEs. In one embodiment, the inter-UE relay may transmit the local ID to the remote UE in a direct communication request message or a direct communication accept message. More specifically, after receiving a direct communication request message from a source remote UE, the inter-UE relay includes the local ID of the source remote UE in another direct communication request message and transmits it to the target remote UE. Both direct communication request messages may also include the upper layer ID of the source remote UE (e.g., the application layer ID of the UE) and the upper layer ID of the target remote UE (e.g., the application layer ID of the UE). And after receiving a direct communication accept message from a target remote UE, the inter-UE relay includes the local ID of the target remote UE in another direct communication accept message and transmits it to the source remote UE. Both direct communication accept messages may also include the upper layer ID of the target remote UE (e.g., the application layer ID of the UE). Considering that there may be multiple source remote UEs, the direct communication accept message or both the direct communication accept message from the target remote UE may also include the upper layer ID of the source remote UE. After the two remote UEs obtain the local ID of the other remote UE, data exchange on the user plane and message exchange on the control plane via the inter-UE relay can be initiated. Figure 18 Explain the above solution.

[0296] After the unicast link between the inter-UE relay and the remote UE has been established, the inter-UE relay may also provide the local ID of the other remote UE to the remote UE. The local ID may be transmitted in a PC5-S message (e.g., a Link Identifier Update Request message, a Link Modify Request message), a sidelink RRC message (e.g., an RRC Reconfiguration Sidelink message), or a sidelink MAC control element (to be specified). In addition to the local ID, the PC5-S message, the sidelink RRC message, or the sidelink MAC control element may also include the upper layer ID of the other remote UE (e.g., the UE's application layer ID) for associating the local ID with the upper layer ID of the other remote UE.

[0297] After a remote UE (UE1) connects with another remote UE (UE2) via an inter-UE relay, data (or traffic) from one remote UE can be forwarded to the other remote UE by the inter-UE relay. It is possible that the remote UE may want to further connect with another remote UE (UE3) via the same inter-UE relay. It is not clear how this is done.

[0298] Since a PC5 unicast link has already been established between the remote UE and the inter-UE relay to support data communication between the two remote UEs, a possible solution to the above problem is for the remote UE to initiate a Layer 2 link modification procedure with the inter-UE relay, allowing the inter-UE relay to further establish another PC5 unicast link with another remote UE. The inter-UE relay may directly initiate the PC5 unicast link establishment procedure with the other remote UE, or may first initiate a discovery procedure to discover the other remote UE before initiating the PC5 unicast link establishment procedure. A security establishment procedure may be performed between the inter-UE relay and the other remote UE during the PC5 unicast link establishment procedure. After completing the above procedure, the remote UE may further initiate an end-to-end link establishment procedure with the other remote UE via the inter-UE relay to establish end-to-end security between the remote UE and the other remote UE. However, end-to-end link establishment may be optional.

[0299] In one embodiment, a link modification request message transmitted by a remote UE to an inter-UE relay to initiate a Layer 2 link modification procedure may include user information of the other remote UE (target user information). The link modification request message may also include user information of the remote UE (source user information), a relay service code (RSC), and / or quality of service (QoS) information 1. In response to receiving the link modification request message, the inter-UE relay may initiate a discovery procedure for the other remote UE or directly initiate a PC5 unicast link establishment procedure with the other remote UE.

[0300] The discovery request message transmitted by the inter-UE relay to another remote UE to initiate a discovery procedure may include the user information of the other remote UE (target user information). The discovery request message may also include the user information of the remote UE (source user information), user information of the inter-UE relay, and / or a relay service code (RSC). In response, the other remote UE may reply with a discovery response message.

[0301] The direct communication request message for initiating the PC5 unicast link establishment procedure transmitted by the inter-UE relay to another remote UE may include the user information of the remote UE (source user information) and the user information of the other remote UE (target user information). The direct communication request message may also include the user information of the inter-UE relay, a relay service code (RSC), security information 1, and / or QoS information 1. In response, the other remote UE may reply with a direct communication accept message. Upon receiving the direct communication accept message from the other remote UE, the inter-UE relay may transmit a link modification accept message to the remote UE. The link modification accept message may include the user information of the remote UE (source user information), the user information of the other remote UE (target user information), a relay service code (RSC), and / or QoS information 2.

[0302] The Relay Service Code (RSC) is a parameter that identifies the service requested by the source remote UE when initiating a connection with the target remote UE. QoS information 2 may be different from QoS information 1 and may be generated by another remote UE based on at least QoS information 1 from the source remote UE. Figure 19 Explain the above solution.

[0303] Figure 20 Flowchart 2000 is provided to illustrate a method for a relay user equipment (UE) to support a connection with another UE. In step 2005, the relay UE establishes a first PC5 unicast link with a first UE and a second PC5 unicast link with a second UE. In step 2010, the relay UE forwards data from the first UE to the second UE. In step 2015, the relay UE receives a link modification request message from the first UE, wherein the link modification request message includes third user information of a third UE. In step 2020, the relay UE transmits a direct communication request message to the third UE, wherein the direct communication request message includes third user information of the third UE. In step 2025, the relay UE receives a direct communication accept message from the third UE. In step 2030, in response to receiving the direct communication accept message, the relay UE transmits a link modification accept message to the first UE.

[0304] In one embodiment, the link modification request message may include first user information of the first UE, a relay service code (RSC), and / or first quality of service (QoS) information. The link modification accept message may include first user information of the first UE, third user information of the third UE, RSC, and / or second quality of service (QoS) information.

[0305] In one embodiment, the direct communication request message may include first user information of the first UE, user information of the relay UE, a relay service code (RSC), first security information, and / or first quality of service (QoS) information. The direct communication acceptance message may include first user information of the first UE, third user information of the third UE, user information of the relay UE, RSC, second security information, and / or second QoS information.

[0306] In one embodiment, after receiving the link modification request message and before transmitting the direct communication request message, the relay UE may transmit a discovery request message to the third UE, wherein the discovery request message includes third user information of the third UE. After transmitting the discovery request message, the relay UE may receive a discovery response message from the third UE.

[0307] In one embodiment, the discovery request message may include the first user information of the first UE, the user information of the relay UE, and / or a relay service code (RSC). The discovery response message may include the first user information of the first UE, the third user information of the third UE, the user information of the relay UE, and / or the RSC.

[0308] In one embodiment, an end-to-end unicast link establishment procedure is performed between a first UE and a third UE via a relay UE. A link modification request message may be received using the first UE's layer 2 ID and the relay UE's layer 2 ID. A link modification accept message may be transmitted using the first UE's layer 2 ID and the relay UE's layer 2 ID.

[0309] Return to view Figure 3 and Figure 4In an exemplary embodiment of a relay UE, the relay UE 300 includes program code 312 stored in a memory 310. The CPU 308 can execute the program code 312 to enable the relay UE to perform the following operations: (i) establish a first PC5 unicast link with a first UE and a second PC5 unicast link with a second UE; (ii) forward data from the first UE to the second UE; (iii) receive a link modification request message from the first UE, wherein the link modification request message includes third user information of a third UE; (iv) transmit a direct communication request message to the third UE, wherein the direct communication request message includes third user information of the third UE; (v) receive a direct communication accept message from the third UE; and (vi) in response to receiving the direct communication accept message, transmit a link modification accept message to the first UE. In addition, the CPU 308 can execute the program code 312 to perform all of the actions and steps described above or other actions and steps described herein.

[0310] 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 that two or more of these aspects can be combined in various ways. For example, a device or method can be implemented using any number of the aspects described herein. In addition, the device or method can be implemented using other structures, functions, or both in addition to or different from one or more of the aspects described herein. As an example 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.

[0311] 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.

[0312] 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., digital implementations, analog implementations, or a combination of both, which may be designed using source decoding or some other technique), various forms of program or design code incorporating instructions (which may be referred to herein for convenience as "software" or "software modules"), or a combination of both. 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.

[0313] 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 combination of multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0314] 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 can 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.

[0315] The steps of the methods or algorithms described in conjunction with the various aspects disclosed herein may be implemented directly in hardware, in software modules executed by a processor, or in a combination of the two. Software modules (e.g., containing executable instructions and associated data) and other data may reside in a data memory, such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of computer-readable storage medium known in the art. An example storage medium may be coupled to a machine such as a computer / processor (for convenience, the machine may be referred to herein as a "processor") so that the processor can read information (e.g., code) from the storage medium and write information to the storage medium. An example storage medium may be integrated with the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user device. In an alternative, the processor and storage medium may reside in a user device as discrete components. In addition, in some aspects, any suitable computer program product may include a computer-readable medium comprising code related to one or more aspects of the present disclosure. In some aspects, a computer program product may include packaging materials.

[0316] 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 relay user equipment to support a connection with another user equipment, characterized in that: include: The relay user equipment establishes a first PC5 unicast link with the first user equipment, and establishes a second PC5 unicast link with the second user equipment; The relay user equipment forwards the data from the first user equipment to the second user equipment; The relay user equipment receives a link modification request message from the first user equipment, wherein the link modification request message includes third user information of a third user equipment; The relay user equipment transmits a direct communication request message to the third user equipment to establish a third PC5 unicast link with the third user equipment, wherein the direct communication request message includes the third user information of the third user equipment; The relay user equipment receives a direct communication acceptance message from the third user equipment; and In response to receiving the direct communication accept message, the relay user equipment transmits a link modification accept message to the first user equipment.

2. The method according to claim 1, characterized in that The link modification request message includes first user information of the first user equipment, a relay service code, or first quality of service information.

3. The method according to claim 2, characterized in that The link modification accept message includes the first user information of the first user equipment, the third user information of the third user equipment, the relay service code or the second quality of service information.

4. The method according to claim 1, wherein The direct communication request message includes first user information of the first user equipment, user information of the relay user equipment, a relay service code, first security information, or first quality of service information.

5. The method according to claim 4, characterized in that The direct communication acceptance message includes the first user information of the first user equipment, the third user information of the third user equipment, the user information of the relay user equipment, the relay service code, second security information, or second quality of service information.

6. The method according to claim 1, characterized in that Further including: After receiving the link modification request message and before transmitting the direct communication request message, the relay user equipment transmits a discovery request message to the third user equipment, wherein the discovery request message includes the third user information of the third user equipment; and After transmitting the discovery request message, the relay user equipment receives a discovery response message from the third user equipment.

7. The method according to claim 6, characterized in that The discovery request message includes the first user information of the first user equipment, the user information of the relay user equipment or the relay service code.

8. The method according to claim 7, characterized in that The discovery response message includes the first user information of the first user equipment, the third user information of the third user equipment, the user information of the relay user equipment, or the relay service code.

9. The method according to claim 1, characterized in that The link modification request message is received using a layer 2 identifier of the first user equipment and a layer 2 identifier of the relay user equipment.

10. The method according to claim 9, characterized in that The link modification accept message is transmitted using the layer 2 identifier of the first user equipment and the layer 2 identifier of the relay user equipment.

11. A relay user equipment, characterized in that: include: control circuit; a processor installed in the control circuit; and 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 first PC5 unicast link with the first user equipment and establishing a second PC5 unicast link with the second user equipment; forwarding data from the first user equipment to the second user equipment; receiving a link modification request message from the first user equipment, wherein the link modification request message includes third user information of a third user equipment; transmitting a direct communication request message to the third user equipment to establish a third PC5 unicast link with the third user equipment, wherein the direct communication request message includes the third user information of the third user equipment; receiving a direct communication acceptance message from the third user equipment; and In response to receiving the direct communication accept message, a link modification accept message is transmitted to the first user equipment.

12. The relay user equipment according to claim 11, characterized in that The link modification request message includes first user information of the first user equipment, a relay service code, or first quality of service information.

13. The relay user equipment according to claim 12, characterized in that: The link modification accept message includes the first user information of the first user equipment, the third user information of the third user equipment, the relay service code or the second quality of service information.

14. The relay user equipment according to claim 11, characterized in that The direct communication request message includes first user information of the first user equipment, user information of the relay user equipment, a relay service code, first security information, or first quality of service information.

15. The relay user equipment according to claim 14, characterized in that: The direct communication acceptance message includes the first user information of the first user equipment, the third user information of the third user equipment, the user information of the relay user equipment, the relay service code, second security information, or second quality of service information.

16. The relay user equipment according to claim 11, characterized in that The processor is further configured to execute program code stored in the memory to: After receiving the link modification request message and before transmitting the direct communication request message, transmitting a discovery request message to the third user equipment, wherein the discovery request message includes the third user information of the third user equipment; and After transmitting the discovery request message, a discovery response message is received from the third user equipment.

17. The relay user equipment according to claim 16, characterized in that: The discovery request message includes the first user information of the first user equipment, the user information of the relay user equipment or the relay service code.

18. The relay user equipment according to claim 17, characterized in that: The discovery response message includes the first user information of the first user equipment, the third user information of the third user equipment, the user information of the relay user equipment, or the relay service code.

19. The relay user equipment according to claim 11, characterized in that The link modification request message is received using a layer 2 identifier of the first user equipment and a layer 2 identifier of the relay user equipment.

20. The relay user equipment according to claim 19, characterized in that The link modification accept message is transmitted using the layer 2 identifier of the first user equipment and the layer 2 identifier of the relay user equipment.

Images