Method and apparatus for relay reselection and data transmission procedures in UE-to-network relay scenarios - Patents.com

Abstract

[0003] Embodiments of the present application relate to a method and apparatus for relay reselection and data transmission procedures in a user equipment (UE)-network relay scenario under 3GPP 5G New Radio (NR). According to one embodiment of the present application, the method may include: establishing a Uu RRC connection for a link between a relay UE and a base station (BS); establishing a PC5 Radio Resource Control (RRC) connection for a link between the UE and the relay UE; and sending a notification to the UE, the notification being associated with at least one of a radio link failure (RLF) for the link between the relay UE and the BS, an RLF recovery failure for the link between the relay UE and the BS, and an RLF recovery success for the link between the relay UE and the BS. In response to receiving the notification, the UE may perform relay reselection and suspend data transmission to the BS.

Description

[Technical field]

[0001] FIELD Embodiments of the present application generally relate to wireless communication technologies, and more particularly, to a method and apparatus for relay reselection and data transmission procedures in a user equipment (UE)-network relay scenario. [Background technology]

[0002] Vehicle to Everything (V2X) has been introduced into 5G wireless communication technology. From the perspective of the channel structure of V2X communication, the direct link between two User Equipments (UEs) is called sidelink. Sidelink is a feature of Long Term Evolution (LTE) introduced in 3GPP Release 12 that enables direct communication between nearby UEs, and data does not need to go through a base station (BS) or core network.

[0003] The Third Generation Partnership Project (3GPP) promotes the deployment of relay nodes (RNs) in wireless communication systems. One purpose of deploying RNs is to enhance the coverage area of ​​a BS by improving the throughput of UEs located in the coverage or far from the BS, which may result in relatively low signal quality. The RN may also be named a relay UE in some cases. A 3GPP 5G sidelink system including a relay UE may be named a sidelink relay system.

[0004] Currently, in 3GPP 5G New Radio (NR) systems and the like, details on how to design relay reselection and data transmission processing procedures in a UE-network relay scenario have not yet been specifically discussed. The UE-network relay scenario may also be named a "U2N relay scenario," "U2N relay," and the like. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP TS 36.300 [Non-Patent Document 2] 3GPP TS 23.303 [Non-Patent Document 3] 3GPP TS 38.311 [Non-Patent Document 4] 3GPP TS 36.311 [Non-Patent Document 5] TS 38.331 Summary of the Invention [Means for solving the problem]

[0006] Some embodiments of the present application provide a method for wireless communication, which may be performed by a relay UE, including: establishing a Uu RRC connection of a link between the relay UE and a base station (BS), establishing a PC5 radio resource control (RRC) connection of a link between the UE and the relay UE, and sending a notification to the UE, the notification being associated with at least one of a radio link failure (RLF) of the link between the relay UE and the BS, an RLF recovery failure of the link between the relay UE and the BS, and an RLF recovery success of the link between the relay UE and the BS.

[0007] Some embodiments of the present application provide a method for wireless communication, which may be performed by a relay UE, including: establishing a PC5 RRC connection of a link between the UE and the relay UE; establishing a Uu RRC connection of a link between the relay UE and a BS; and transmitting failure information to the BS in response to detecting a PC5 signaling (PC5-S) link failure in the link between the UE and the relay UE.

[0008] Some embodiments of the present application also provide an apparatus for wireless communication that includes a non-transitory computer-readable medium having computer-executable instructions stored thereon, a receiving circuitry, a transmitting circuitry, and a processor coupled to the non-transitory computer-readable medium, the receiving circuitry, and the transmitting circuitry, the computer-executable instructions causing the processor to implement any of the above-mentioned methods performed by a relay UE.

[0009] Some embodiments of the present application provide a further method for wireless communication, which may be performed by a UE, including the steps of: establishing a PC5 RRC connection of a link between the UE and a relay UE, where a Uu RRC connection of a link between the relay UE and a BS is established; and receiving a notification from one of the relay UE and the BS, where the notification received from the BS is a request to perform a relay reselection procedure, and the notification received from the relay UE is associated with at least one of an RLF of the link between the relay UE and the BS, an RLF recovery failure of the link between the relay UE and the BS, and an RLF recovery success of the link between the relay UE and the BS.

[0010] Some embodiments of the present application provide a method for wireless communication, which may be performed by a UE, including the steps of: establishing a PC5 RRC connection of a link between the UE and a relay UE, where a Uu RRC connection of a link between the relay UE and a BS is established; establishing an RRC relay connection of the link between the UE and the BS; and performing a relay reselection procedure in response to expiration of a timer for RRC relay connection reconfiguration of the link between the UE and the BS and in response to receiving a relay reselection indication from the BS.

[0011] Some embodiments of the present application also provide an apparatus for wireless communication that includes a non-transitory computer-readable medium having computer-executable instructions stored thereon, a receiving circuitry, a transmitting circuitry, and a processor coupled to the non-transitory computer-readable medium, the receiving circuitry, and the transmitting circuitry, the computer-executable instructions causing the processor to implement any of the above-mentioned methods performed by a UE.

[0012] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

[0013] To describe the manner in which the advantages and features of the present application can be obtained, the present application will be described by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and are therefore not to be considered as limiting its scope. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of a wireless communication system in accordance with some embodiments of the present application. [Diagram 2] 1 is an illustrative V2X communication system in accordance with some embodiments of the present application. [Diagram 3] 1 is an example flowchart of a sidelink RRC reconfiguration procedure in accordance with some embodiments of the present application. [Figure 4] 1 is an example flowchart of a sidelink UE information procedure in accordance with some embodiments of the present application. [Diagram 5] 1 is an illustrative flowchart of a Layer 2 link maintenance procedure in accordance with some embodiments of the present application. [Figure 6] 4 is a flowchart of a method for sending a notification to a UE according to some embodiments of the present application. [Figure 7] 1 is a flowchart of a method for receiving a notification from one of a BS and a relay UE according to some embodiments of the present application. [Figure 8] 1 is a flowchart of a method for performing a relay reselection procedure according to some embodiments of the present application. [Figure 9] 4 is a flowchart of a method for sending fault information to a BS according to some embodiments of the present application. [Figure 10] FIG. 1 is a simplified block diagram of an apparatus for a fault handling procedure according to some embodiments of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The detailed description of the accompanying drawings is intended as an illustration of a preferred embodiment of the present application, and is not intended to represent the only form in which the present application may be practiced. It should be understood that the same or equivalent functions may be accomplished by various embodiments that are intended to be encompassed within the spirit and scope of the present application.

[0016] Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. For ease of understanding, the embodiments are provided under specific network architectures and new service scenarios, such as 3GPP 5G, 3GPP LTE Release 8, etc. With the development of network architectures and new service scenarios, it is contemplated that all the embodiments in the present application are also applicable to similar technical problems, and furthermore, the technical terms listed in the present application may change, but should not affect the principle of the present application.

[0017] FIG. 1 illustrates a schematic diagram of a wireless communication system in accordance with some embodiments of the present application.

[0018] 1, the wireless communication system 100 includes, for illustrative purposes, a UE 101, a BS 102, and a relay UE 103. The UE 101 may also be termed a "remote UE," etc. Although a particular number of UEs, relay UEs, and BSs are depicted in FIG. 1, it is contemplated that any number of UEs, relay UEs, and BSs may be included in the wireless communication system 100.

[0019] Due to the long distance between UE 101 and BS 102, they communicate with each other via relay UE 103. UE 101 may be connected to relay UE 103 via a network interface, for example, a PC5 interface as defined in 3GPP standard documents. Relay UE 103 may be connected to BS 102 via a network interface, for example, a Uu interface as defined in 3GPP standard documents. Referring to FIG. 1, UE 101 is connected to relay UE 103 via a PC5 link, and relay UE 103 is connected to BS 102 via a Uu link.

[0020] In some embodiments of the present application, the UE 101 or relay UE 103 may include a computing device such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart television (e.g., a television connected to the Internet), a set-top box, a game console, a security system (including security cameras), a vehicle-mounted computer, a network device (e.g., routers, switches, and modems), and the like.

[0021] In some further embodiments of the present application, the UE 101 or relay UE 103 may include a portable wireless communications device, a smartphone, a cellular phone, a flip phone, a device having a subscriber identity module, a personal computer, a selective call receiving network, or any other device capable of transmitting and receiving communication signals over a wireless network.

[0022] In some other embodiments of the present application, the UE 101 or relay UE 103 may include a wearable device, such as a smart watch, a fitness band, an optical head mounted display, etc. Additionally, the UE 101 or relay UE 103 may be referred to as a subscriber unit, a mobile, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal or device, or described using other technical terms used in the art.

[0023] The BSs 102 may be distributed throughout a geographic region. In some embodiments of the present application, each of the BSs 102 may be referred to as an access point, access terminal, base, base unit, macro cell, Node B, evolved Node B (eNB), gNB, Home Node B, relay node or device, or described using other terminology used in the art. The BSs 102 are generally part of a radio access network that may include one or more controllers communicatively coupled to one or more corresponding BSs 102.

[0024] The wireless communication system 100 may be compatible with any type of network capable of transmitting and receiving wireless communication signals. For example, the wireless communication system 100 may be compatible with a wireless communication network, a cellular telephone network, a time division multiple access (TDMA) based network, a code division multiple access (CDMA) based network, an orthogonal frequency division multiple access (OFDMA) based network, an LTE network, a 3GPP based network, a 3GPP 5G network, a satellite communication network, a high altitude platform network, and / or other communication networks.

[0025] In some embodiments of the present application, the wireless communication system 100 is compatible with the 3GPP protocol 5G NR, where the BS 102 transmits data on the downlink (DL) using an OFDM modulation scheme, and the UE 101 (e.g., the UE 101 or other similar UEs) transmits data on the uplink (UL) using a Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) or Cyclic Prefix OFDM (CP-OFDM) scheme. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocol, such as WiMAX, among other protocols.

[0026] In some embodiments of the present application, the BS 102 may communicate using other communication protocols, such as the IEEE 802.11 family of wireless communication protocols. Additionally, in some embodiments of the present application, the BS 102 may communicate over licensed spectrum, while in other embodiments, the BS 102 may communicate over unlicensed spectrum. This application is not intended to be limited to any particular wireless communication system architecture or protocol implementation. In further embodiments of the present application, the BS 102 may communicate with the UE 101 using 3GPP 5G protocols.

[0027] The UE 101 may access the BS 102 to receive data packets from the BS 102 via a downlink channel and / or transmit data packets to the BS 102 via an uplink channel. In normal operation, the UE 101 does not know when the BS 102 transmits data packets to the UE 101, so the UE 101 must be constantly awake and monitor a downlink channel (e.g., a physical downlink control channel (PDCCH)) to prepare to receive data packets from the BS 102. However, if the UE 101 keeps constantly monitoring the downlink channel even when there is no traffic between the BS 102 and the UE 101, it will lead to significant power waste, which is problematic for power-limited or power-sensitive UEs.

[0028] In general, sidelink communication supports UE-UE direct communication using two transmission modes. Two sidelink resource allocation modes are supported, namely, Mode 1 and Mode 2. In Mode 1, sidelink resources are scheduled by the BS. In Mode 2, the UE decides the sidelink transmission resources and timing in a resource pool based on measurement and sensing results. Sidelink communication includes NR sidelink communication and V2X sidelink communication. Figure 2 below shows NR sidelink communication. V2X sidelink communication is specified in 3GPP TS 36.300.

[0029] FIG. 2 illustrates an exemplary V2X communications system in accordance with some embodiments of the present application.

[0030] 2, the V2X communication system includes one gNB 202, one ng-eNB 203, and several V2X UEs, namely UE 201-A, UE 201-B, and UE 201-C, each of which may be referred to as UE 101a, UE 101b, or relay UE 103 as shown and illustrated in FIG.

[0031] In particular, UE 201-A is in the coverage of gNB 202, UE 201-B is in the coverage of ng-eNB 203, and UE 201-C is out of the coverage of gNB 202 and ng-eNB 203. Support for V2X services over the PC5 interface can be provided by NR sidelink communication and / or V2X sidelink communication. NR sidelink communication can support one of three transmission modes for a pair of source Layer 2 identity (ID) and destination Layer 2 ID: unicast transmission, groupcast transmission, and broadcast transmission. Sidelink transmission and reception over the PC5 interface is supported when the UE is inside or outside the NG-RAN coverage.

[0032] UE 201-A is within the coverage of gNB 202 and may perform sidelink unicast, groupcast or broadcast transmissions over the PC5 interface, and UE 201-C is out of coverage but may also perform sidelink transmissions and receptions over the PC5 interface.

[0033] In accordance with some other embodiments of the present application, it is contemplated that a V2X communication system may include more or fewer BSs and more or fewer V2X UEs. Moreover, it is contemplated that the names of the V2X UEs (representing Tx UE, Rx UE, etc.) as illustrated and depicted in FIG. 2 may be different, such as UE 201c, UE 204f, and UE 208g.

[0034] Additionally, although each V2X UE as depicted in FIG. 2 is illustrated in the form of a mobile phone, it is contemplated that a V2X communications system may include any type of UE (e.g., a road map device, a mobile phone, a computer, a laptop, an IoT (Internet of Things) device, or other type of device) in accordance with certain other embodiments of the present application.

[0035] According to some embodiments of FIG. 2, UE 201-A functions as a Tx UE, and UE 201-B and UE 201-C function as Rx UEs. UE 201-A may exchange V2X messages with UE 201-B or UE 201-C through a sidelink, e.g., a PC5 interface as defined in 3GPP TS 23.303. UE 201-A may transmit information or data to other UEs in the V2X communication system through a sidelink unicast, a sidelink groupcast, or a sidelink broadcast. Sidelink communications include NR sidelink communications and V2X sidelink communications. For example, UE 201-A may transmit data to UE 201-C in an NR sidelink unicast session, and UE 201-B may transmit data to UE 201-C in a V2X sidelink unicast session. The UE 201-A may transmit data to the UEs 201-B and 201-C in the groupcast group via a sidelink groupcast transmission session.

[0036] Sidelink communication includes NR sidelink communication and V2X sidelink communication. Figure 2 shows NR sidelink communication as specified in 3GPP TS 38.311. V2X sidelink communication is specified in 3GPP TS 36.311.

[0037] FIG. 3 illustrates an example flow chart of a sidelink RRC reconfiguration procedure in accordance with some embodiments of the present application.

[0038] As shown in FIG. 3, in operation 301, a UE 310 (e.g., a UE 101a as illustrated and shown in FIG. 1) initiates a sidelink RRC reconfiguration procedure for a UE 320 (e.g., a relay UE 103 as illustrated and shown in FIG. 1) by sending an RRCReconfigurationSidelink message to the UE 320.

[0039] If the sidelink RRC reconfiguration procedure is completed successfully, then in operation 302 the UE 320 may send an "RRC reconfiguration complete sidelink message", e.g., an RRCReconfigurationCompleteSidelink message as defined in the 3GPP standard documents, to the UE 310. Alternatively, if the sidelink RRC reconfiguration procedure is not completed successfully, then in operation 302 the UE 320 may send an "RRC reconfiguration failure sidelink message", e.g., an RRCReconfigurationFailureSidelink message as defined in the 3GPP standard documents, to the UE 310.

[0040] The purpose of the sidelink RRC reconfiguration procedure is to modify the PC5 RRC connection, e.g. to establish, modify or release sidelink Data Radio Bearers (DRBs), to configure NR sidelink measurements and reporting, and to configure sidelink Channel State Information (CSI) reference signal resources.

[0041] A UE (e.g., UE 310 as illustrated and shown in FIG. 3) may initiate a sidelink RRC reconfiguration procedure and take action on the corresponding PC5 RRC connection if: - release of a sidelink DRB associated with a peer UE (e.g. UE 320 as illustrated and shown in FIG. 3 ); - Establishment of a sidelink DRB associated with the peer UE; - changes to parameters contained in the Sidelink Radio Bearer (SLRB)-Config of a Sidelink DRB associated with the peer UE; - configuration information of the peer UE for NR sidelink measurements and reporting; and - Configuration information for sidelink CSI reference signal resources.

[0042] A UE capable of NR sidelink communication may initiate a sidelink UE information procedure for NR to report to the network or BS that a sidelink Radio Link Failure (RLF) (e.g., expiration of timer T400) or a sidelink RRC reconfiguration failure has been declared.

[0043] The following table shows an introduction to some timers as specified in the 3GPP standard documents, including the start conditions, stop conditions, action on expiration and possible common names for each of these timers.

[0044] [Table 1]

[0045] FIG. 4 illustrates an example flowchart of a sidelink UE information procedure in accordance with some embodiments of the present application.

[0046] As illustrated in Fig. 4, in operation 401, a UE 410 (e.g., a UE 101a as illustrated and shown in Fig. 1 or a UE 310 as illustrated and shown in Fig. 3) sends a "sidelink UE information message", e.g., a SidelinkUEinformationNR message as defined in the 3GPP standard documents, to a BS 420 (e.g., a BS 102 as illustrated and shown in Fig. 1). Specifically, the sidelinkUEinformationNR message may include sidelink failure information. The sidelink failure information may include a sidelink destination information ID and a sidelink failure cause.

[0047] According to the 3GPP standard document, in the keep-alive procedure at the PC5-S layer, the PC5-S protocol shall support a keep-alive functionality used to detect whether a particular PC5 unicast link is still valid. The UE shall minimize the keep-alive signaling, e.g., cancel the procedure if data is successfully received over the PC5 unicast link.

[0048] FIG. 5 illustrates an exemplary flow chart of a layer 2 link maintenance procedure according to some embodiments of the present application.

[0049] As illustrated in FIG. 5, in step 0, UE-1 (e.g., UE 101a, UE 201-C, UE 310, or UE 410 as illustrated and shown in FIG. 1-4) and UE-2 (e.g., relay UE 103, UE 201-A, or UE 320 as illustrated and shown in FIG. 1-3) establish a unicast link. In step 1, UE-1 (e.g., UE 101a as illustrated and shown in FIG. 1) sends a keep-alive message to UE-2 (e.g., relay UE 103 as illustrated and shown in FIG. 1) to determine the state of the PC5 unicast link based on a trigger condition. In step 2, in response to receiving the keep-alive message, UE-2 responds with a keep-alive Ack message to UE-1. When UE-1 receives a response from UE-2, UE-1 stops the "timer for the keep-alive procedure". Otherwise, the "timer for the keep-alive procedure" expires.

[0050] According to 3GPP standard documents, an adaptation layer is supported across the PC5 link (i.e., the PC5 link between the relay UE and the remote UE) for Layer 2 (i.e., L2) UE-to-network relay scenarios. For L2 UE-to-network relay scenarios, the adaptation layer is placed above the RLC sublayer for both the control plane (CP) and the user plane (UP) across the PC5 link. The Sidelink Service Data Adaptation Protocol (SDAP) or Sidelink Packet Data Convergence Protocol (PDCP) and RRC are terminated between the two remote UEs, while the RLC, MAC and PHY are terminated at each PC5 link.

[0051] For a Layer 3 (i.e., L3) UE-to-network relay scenario, the relay UE has a complete protocol stack: the user plane (UP) protocol stack of the L3 relay UE includes PHY, MAC, RLC, PDCP and SDAP layers, and the control plane (CP) protocol stack of the L3 relay UE includes PHY, MAC, RLC, PDCP and RRC layers.

[0052] Currently, in the sidelink relay system under the 3GPP 5G NR network, the following problems need to be solved: what is the triggering condition for the remote UE to perform relay reselection in the UE-network relay scenario, what is the behavior of the remote UE in response to receiving the notification, and whether the relay UE needs to report to the BS when the relay UE fails to complete the keep-alive procedure in the UE-network relay scenario. Details on how to design the relay reselection procedure and connection processing procedure in the UE-network relay scenario have not yet been specifically discussed. The embodiments of the present application provide a relay reselection and connection processing procedure in the UE-network relay scenario in the 3GPP 5G NR system, etc., to solve the above problems. Further details will be illustrated in the following text in combination with the accompanying drawings.

[0053] FIG. 6 illustrates a flowchart of a method for sending a notification to a UE according to some embodiments of the present application.

[0054] The method may be performed by a relay UE (e.g., relay UE 103 as illustrated and shown in FIG. 1, UE 201-A or UE 201-B as illustrated and shown in FIG. 2, or UE 320 as illustrated and shown in FIG. 3). Although described with respect to a relay UE, it should be understood that other devices may be configured to perform a method similar to that of FIG.

[0055] In an exemplary method 600 as illustrated in Figure 6, a Uu RRC connection of a link between a relay UE (e.g., relay UE 103 illustrated and shown in Figure 1) and a BS (e.g., BS 102 illustrated and shown in Figure 1) is established in operation 601. A PC5 RRC connection of a link between a UE (e.g., UE 101a illustrated and shown in Figure 1) and a relay UE is established in operation 602.

[0056] In operation 603, the relay UE sends a notification to the UE. For example, the failure notification sent from the relay UE may be associated with at least one of an RLF of a link between the relay UE and the BS, an RLF recovery failure of a link between the relay UE and the BS, and an RLF recovery success of a link between the relay UE and the BS.

[0057] In some embodiments, the notification sent by the relay UE is an RLF notification. (1) A relay UE detects an RLF on the link between the relay UE and the BS; (2) the relay UE performs a fast master cell group (MCG) link recovery procedure on the link between the relay UE and the BS; and (3) The relay UE performs an RRC re-establishment procedure on the link between the relay UE and the BS. To some extent, the RRC re-establishment procedure is a means of recovery.

[0058] In some other embodiments, the notification is a recovery success notification. In one example, the relay UE sends the recovery success notification in response to successfully completing a fast MCG link recovery procedure on the link between the relay UE and the BS. In another example, the relay UE sends the recovery success notification in response to successfully completing an RRC re-establishment procedure on the link between the relay UE and the BS.

[0059] In some further embodiments, the notification is a recovery failure notification. For example, the relay UE sends the recovery failure notification in response to a failure to complete an RRC re-establishment procedure on a link between the relay UE and the BS. Alternatively, the relay UE sends the recovery failure notification in response to expiration of a timer for transmission of an RRC re-establishment request message. For example, the relay UE sends the recovery failure notification if timer T301 expires.

[0060] In some embodiments, the notification comprises: (1) A Medium Access Control (MAC) Control Element (CE) of a Relay UE; (2) RRC signaling for the relay UE; and (3) Transmitted by at least one of a control packet data unit (PDU) in an adaptation layer of the relay UE.

[0061] Details described in all other embodiments of the present application (e.g. details regarding notification sent from the relay UE) are applicable to the embodiment of Fig. 6. Moreover, details described in the embodiment of Fig. 6 are applicable to all embodiments of Figs. 1-5 and 7-10.

[0062] FIG. 7 illustrates a flowchart of a method for receiving a notification from one of a BS and a relay UE according to some embodiments of the present application.

[0063] The method may be performed by a UE (e.g., UE 101a as illustrated and shown in FIG. 1, UE 201-C as illustrated and shown in FIG. 2, UE 310 as illustrated and shown in FIG. 3, or UE 410 as illustrated and shown in FIG. 4). Although described with respect to a UE, it should be understood that other devices may be configured to perform a method similar to that of FIG.

[0064] In an exemplary method 700 as illustrated in Figure 7, a PC5 RRC connection of a link between a UE (e.g., UE 101a as illustrated and shown in Figure 1) and a relay UE (e.g., relay UE 103 as illustrated and shown in Figure 1) is established in operation 701. The embodiment of Figure 7 assumes that a Uu RRC connection of a link between a relay UE and a BS (e.g., BS 102 as illustrated and shown in Figure 1) has been established.

[0065] In operation 702, the UE receives a notification from one of the BS and the relay UE. The notification received from the BS is a request to perform a relay reselection procedure. The notification received from the relay UE is (1) Radio Link Failure (RLF) of the link between the relay UE and the BS; (2) RLF recovery failure of the link between the relay UE and the BS; (3) Associated with at least one of the RLF recovery success of the link between the relay UE and the BS.

[0066] In some embodiments, the notification is an RLF notification sent from a relay UE. The relay UE may send the RLF notification after the relay UE detects an RLF on a link between the relay UE and a BS. The relay UE may send the RLF notification after the relay UE performs a fast MCG link recovery procedure on a link between the relay UE and a BS. Alternatively, the relay UE may send the RLF notification after the relay UE performs an RRC re-establishment procedure on a link between the relay UE and a BS.

[0067] In some other embodiments, the notification is a recovery success notification. In one example, the relay UE sends the recovery success notification if the relay UE successfully completes a fast MCG link recovery procedure for the link between the relay UE and the BS. In another example, the relay UE sends the recovery success notification if the relay UE successfully completes an RRC re-establishment procedure for the link between the relay UE and the BS.

[0068] In some further embodiments, the notification is a recovery failure notification. For example, if the relay UE fails to complete an RRC re-establishment procedure on a link between the relay UE and the BS, the relay UE sends the recovery failure notification. Alternatively, the relay UE sends the recovery failure notification in response to expiration of a timer for transmitting an RRC re-establishment request message. For example, if timer T301 expires, the relay UE sends the recovery failure notification.

[0069] In some embodiments, the notification is sent by at least one of the MAC CE of the relay UE, the RRC signaling of the relay UE, and a control PDU in the adaptation layer of the relay UE.

[0070] In some embodiments, in the illustrative method 700, the UE further performs a relay reselection procedure after receiving a notification associated with at least one of "RLF of a link between the relay UE and the BS" and "RLF recovery failure of a link between the relay UE and the BS."

[0071] In one embodiment, when the UE receives a notification associated with the RLF of the link between the relay UE and the BS, the UE: - a Data Radio Bearer (DRB) addressed to the BS; - transmitting data addressed to the BS; and - It may interrupt at least one of the transmissions of signaling addressed to the BS.

[0072] In some other embodiments, if the UE receives a notification associated with the RLF of the link between the relay UE and the BS, the UE may continue to send data addressed to the relay UE and receive data from the relay UE.

[0073] In some embodiments, if the UE receives an end mark indication from the relay UE, the UE stops receiving data from the relay UE. In some further embodiments, if the UE receives an RRC message and the RRC message includes an indication that transmission of data destined for the UE has been completed, the UE stops receiving data from the relay UE.

[0074] In one embodiment, the AS layer of the UE may send an indication to the PC5-S layer of the UE to indicate that the UE has stopped receiving data from the relay UE.

[0075] In a further embodiment, the AS layer of the UE may send an indication to the PC5-S layer of the UE to indicate the occurrence of a failure in the link between the relay UE and the BS, and the PC5-S layer of the UE then sends a discovery message to the AS layer of the UE.

[0076] In some embodiments, the UE initiates a relay discovery procedure or initiates a relay reselection procedure if the UE receives a notification associated with an RLF recovery failure of the link between the relay UE and the BS. In some other embodiments, the UE initiates a relay discovery procedure or initiates a relay reselection procedure if the UE receives a notification associated with an RLF recovery failure of the link between the relay UE and the BS.

[0077] In some embodiments, the UE may receive a recovery success notification from the relay UE, and the UE resumes at least one of transmitting a DRB addressed to the BS, data addressed to the BS, and signaling addressed to the BS.

[0078] Details described in all other embodiments of the present application (e.g. details regarding notifications received from the BS or relay UE) are applicable to the embodiment of Fig. 7. Moreover, details described in the embodiment of Fig. 7 are applicable to all embodiments of Figs. 1-6 and 8-10.

[0079] FIG. 8 illustrates a flowchart of a method for performing a relay reselection procedure according to some embodiments of the present application.

[0080] The method may be performed by a UE (e.g., UE 101a as illustrated and shown in FIG. 1, UE 201-C as illustrated and shown in FIG. 2, UE 310 as illustrated and shown in FIG. 3, or UE 410 as illustrated and shown in FIG. 4). Although described with respect to a UE, it should be understood that other devices may be configured to perform a method similar to that of FIG.

[0081] In an exemplary method 800 as illustrated in Figure 8, a PC5 RRC connection of a link between a UE (e.g., UE 101a as illustrated and shown in Figure 1) and a relay UE (e.g., relay UE 103 as illustrated and shown in Figure 1) is established in operation 801. The embodiment of Figure 8 assumes that a Uu RRC connection of a link between a relay UE and a BS (e.g., BS 102 as illustrated and shown in Figure 1) has been established.

[0082] In operation 802, an RRC relay connection of a link between the UE and the BS is established. In operation 803, the UE performs a relay reselection procedure in response to "expiration of a timer for RRC relay connection reconfiguration of a link between the UE and the BS" or "receiving a relay reselection indication from the BS."

[0083] The RRC relay connection of the link between the UE and the BS may also be termed an "end-to-end RRC connection of the relay link", an "end-to-end RRC connection", an "end-to-end relay connection", an "relay RRC connection", etc.

[0084] In some embodiments, the UE may further send an RRC message to the BS. The RRC message may be relayed to the BS by the relay UE. In response to sending the RRC message, the UE may start a timer for RRC relay connection reconfiguration.

[0085] In some embodiments, the UE receives measurement configuration information including identification information of candidate relay UEs from the BS. The UE then performs measurements on the candidate relay UEs and transmits the measurement results of the measurements to the BS. For example, based on a condition that the channel quality of the link between the UE and the relay UE is below a threshold, the UE may perform measurements on the candidate relay UEs and the UE's neighboring cells in addition to the UE's serving cell (if any). If the UE is within the coverage of the BS, the UE has a serving cell and may perform measurements on the serving cell. Otherwise, the UE cannot find a serving cell and only needs to perform measurements on the candidate relay UEs and the UE's neighboring cells. The UE then transmits the measurement results of the performed measurements to the BS. Based on the received measurement results, the BS may send a relay reselection indication to the UE. In response to receiving the relay reselection indication, the UE may perform a relay reselection procedure.

[0086] In some embodiments, the UE receives an RRC message from the BS. The RRC message includes a relay reselection indication. In one embodiment, the relay reselection indication is associated with measurement results of measurements made by the UE. For example, measurements are made on candidate relay UEs, the UE's serving cell (if any), and the UE's neighbor cells.

[0087] Details described in all other embodiments of the present application (e.g. details regarding trigger conditions for a relay reselection procedure) are applicable to the embodiment of Fig. 8. Moreover, details described in the embodiment of Fig. 8 are applicable to all embodiments of Figs. 1-7, 9 and 10.

[0088] The following text describes specific embodiments 1-4 of the method as shown and exemplified in any of FIGS.

[0089] EMBODIMENT 1 The first embodiment is for an L3 UE-network relay scenario. There is no end-to-end RRC connection between the remote UE and the BS in the first embodiment. According to the first embodiment, the UE1 (e.g., the UE101 as shown and illustrated in FIG. 1, which serves as a remote UE), the relay UE (e.g., the relay UE103 as shown and illustrated in FIG. 1), and the BS (e.g., the BS102 as shown and illustrated in FIG. 1) perform the following steps: (1) Step 1: A PC5 RRC connection between UE1 and the relay UE is established. A Uu RRC connection between the relay UE and the BS is established. (2) Step 2: The relay UE sends a notification to UE1 based on at least one of the following conditions: ● When an RLF occurs on the Uu interface between the relay UE and the BS, the relay UE sends a notification associated with the RLF to UE1. For example, the notification associated with the RLF is an RLF notification. The relay UE may send the RLF notification in response to detecting the RLF. The RLF notification may be carried on the MCG link via the MAC CE of the relay UE. The RLF notification may be carried on an RRC message of the relay UE. Alternatively, the RLF notification may be carried on an adaptation layer control PDU of the relay UE. ● If the RLF recovery procedure fails on the Uu interface between the relay UE and the BS, the relay UE sends a notification associated with the RLF recovery failure to UE1. (3) Step 3: After receiving the notification from the relay UE, UE1 performs a relay reselection procedure.

[0090] EMBODIMENT 2 The second embodiment is for an L2 UE-network relay scenario. In the second embodiment, there is an end-to-end RRC connection between a remote UE and a BS. According to the second embodiment, a UE1 (e.g., a UE101 as shown and illustrated in FIG. 1, which serves as a remote UE), a relay UE (e.g., a relay UE103 as shown and illustrated in FIG. 1), and a BS (e.g., a BS102 as shown and illustrated in FIG. 1) perform the following steps: (1) Step 1: A PC5 RRC connection between UE1 and the relay UE is established. A Uu RRC connection between the relay UE and the BS is established. (2) Step 2: An end-to-end RRC connection between UE1 and the BS is established. UE1 sends an RRC setup request to the BS via the relay UE. The BS sends an RRC setup message to UE1 via the relay UE. The RRC setup message includes a response to UE1. (3) Step 3: The relay UE sends a notification to UE1 based on at least one of the following conditions: A timer for an end-to-end RRC message expires - UE1 sends an RRC message to the BS, which is relayed to the BS by the relay UE. One timer is used to control the RRC procedure. This timer may also be named "timer for end-to-end RRC message" etc. When UE1 sends an RRC message, UE1 starts this timer. If the UE receives a response or feedback from the BS, the UE stops this timer. Otherwise, once this timer expires, UE1 is triggered to perform a relay reselection procedure. ●UE1 receives an RRC message from the BS, and the RRC message contains a relay reselection indication. The RRC message received from the BS may further include the identity of the candidate relay UE. The BS may configure the UE to perform measurements on the candidate relay UE, UE1's serving cell and UE1's neighboring cells. UE1 may report the measurement results of the measurements to the BS, for example in a measurement report. Based on the measurement report from UE1, the BS may configure UE1 to perform a relay reselection procedure. (4) Step 4: UE1 performs relay reselection procedure.

[0091] EMBODIMENT 3 According to embodiment 3, a UE1 (e.g., a UE101 as illustrated and illustrated in FIG. 1, serving as a remote UE), a relay UE (e.g., a relay UE103 as illustrated and illustrated in FIG. 1), and a BS (e.g., a BS102 as illustrated and illustrated in FIG. 1) perform the following steps: (1) Step 1: A PC5 RRC connection between UE1 and the relay UE is established. A Uu RRC connection between the relay UE and the BS is established. (2) Step 2 (optional): If the UE-network relay is an L2 relay scenario, an end-to-end RRC connection between UE1 and the BS is established. UE1 sends an RRC setup request to the BS via the relay UE. The BS sends an RRC setup message to UE1 via the relay UE. The RRC setup message includes a response to UE1. (3) Step 3: The relay UE sends a notification to UE1 based on at least one of the following conditions: ●Relay UE is, - RLF between the relay UE and the BS occurs, or - the relay UE is triggered to perform a fast MCG link recovery procedure, or - When the relay UE is triggered to perform an RRC re-establishment procedure, it sends an RLF notification to UE1. The RLF notification can be sent by the MAC CE of the relay UE, by RRC signaling of the relay UE, or by a control PDU in the adaptation layer of the relay UE. Step 4: UE1 receives an RLF notification from the relay UE. - After UE1 receives the RLF notification from the relay UE, UE1 suspends DRB or data and signaling transmissions addressed to the BS. - UE1 may continue to send data transmissions addressed to the relay UE to the relay UE. - UE1 may continue to receive data from the relay UE, the data in the buffer of the relay UE may have been sent from the BS. After the relay UE completes data transmission, the relay UE may send end mark information to UE1. Optionally, the relay UE may send an RRC message to UE1 to indicate the completion of data transmission. Then, UE1 will perform a relay reselection procedure. - UE1 is triggered to start a discovery procedure or a relay reselection procedure. - The AS layer of UE1 notifies the upper layer of UE1 (e.g., the V2X layer or the PC5-S layer) that the Uu interface has failed. The upper layer of UE1 then provides a discovery message to the AS layer of UE1 for transmission. - Step 5: The relay UE sends a recovery success notification in response to "Fast MCG link recovery procedure successful" or "Re-establishment recovery procedure successful". - After receiving a successful recovery notification from the relay UE, UE1 may resume data transmission with the BS. - The recovery success notification can be sent by the MAC CE of the relay UE, by RRC signaling of the relay UE, or by a control PDU in the adaptation layer of the relay UE.

[0092] EMBODIMENT 4 According to embodiment 4, a UE1 (e.g., a UE101 as illustrated and illustrated in FIG. 1, serving as a remote UE), a relay UE (e.g., a relay UE103 as illustrated and illustrated in FIG. 1), and a BS (e.g., a BS102 as illustrated and illustrated in FIG. 1) perform the following steps: (1) A PC5 RRC connection between UE1 and the relay UE is established. A Uu RRC connection between the relay UE and the BS is established. (2) Step 2 (optional): If the UE-network relay is an L2 relay scenario, an end-to-end RRC connection between UE1 and the BS is established. UE1 sends an RRC setup request to the BS via the relay UE. The BS sends an RRC setup message to UE1 via the relay UE. The RRC setup message includes a response to UE1. (3) Step 3: The relay UE sends a recovery failure notification to UE1 based on at least one of the following conditions: ● The relay UE sends a recovery failure notification to UE1 in response to a recovery failure, such as expiration of timer T304 or expiration of timer T301. - When UE1 receives the recovery failure notification, UE1 is triggered to perform a relay reselection procedure. The recovery failure notification can be sent by the MAC CE of the relay UE, by RRC signaling of the relay UE, or by a control PDU in the adaptation layer of the relay UE.

[0093] FIG. 9 illustrates a flowchart of a method for sending fault information to a BS according to some embodiments of the present application.

[0094] The method may be performed by a relay UE (e.g., relay UE 103 as illustrated and shown in FIG. 1, UE 201-A or UE 201-B as illustrated and shown in FIG. 2, or UE 320 as illustrated and shown in FIG. 3). Although described with respect to a relay UE, it should be understood that other devices may be configured to perform a method similar to that of FIG.

[0095] In an example method 900 as illustrated in FIG 9, a PC5 RRC connection is established for a link between a UE (e.g., UE 101a as illustrated and shown in FIG 1) and a relay UE (e.g., relay UE 103 as illustrated and shown in FIG 1) at operation 901. A Uu RRC connection is established for a link between the relay UE and a BS (e.g., BS 102 as illustrated and shown in FIG 1).

[0096] At operation 903, in response to detecting a PC5-S link failure in a link between the UE and the relay UE, the relay UE transmits failure information to the UE.

[0097] In some embodiments, the relay UE: - expiry of a timer for a keep-alive procedure, the timer for the keep-alive procedure being associated with a link between the UE and the relay UE; - the AS layer of the relay UE receives, from the PC5-S layer of the relay UE, an indication of a PC5-S link failure; and - the relay UE sends the failure information in response to at least one of the following: - the relay UE declares a sidelink RLF in response to detecting a PC5-S link failure.

[0098] In some embodiments, the failure information is a sidelink failure notification, and the sidelink failure notification includes a cause. The cause may be: 1) expiration of a timer for a keep-alive procedure, the timer for the keep-alive procedure being associated with a link between the UE and the relay UE; and 2) Occurrence of a PC5-S link failure.

[0099] Details described in all other embodiments of the present application (e.g. details regarding fault information transmitted to the BS) are applicable to the embodiment of Fig. 9. Moreover, details described in the embodiment of Fig. 9 are applicable to all embodiments of Figs. 1-8 and 10.

[0100] The following text describes a specific embodiment 5 of the method as depicted and illustrated in FIG.

[0101] EMBODIMENT 5 According to embodiment 5, a UE1 (e.g., a UE101 as illustrated and illustrated in FIG. 1, serving as a remote UE), a relay UE (e.g., a relay UE103 as illustrated and illustrated in FIG. 1), and a BS (e.g., a BS102 as illustrated and illustrated in FIG. 1) perform the following steps: (1) A PC5 RRC connection between UE1 and the relay UE is established. A Uu RRC connection between the relay UE and the BS is established. (2) Step 2 (optional): If the UE-network relay is an L2 relay scenario, an end-to-end RRC connection between UE1 and the BS is established. UE1 sends an RRC setup request to the BS via the relay UE. The BS sends an RRC setup message to UE1 via the relay UE. The RRC setup message includes a response to UE1. (3) Step 3: The relay UE sends a keep-alive message to UE1 to determine the status of the PC5 unicast link based on the trigger condition. ● The relay UE starts one timer for the keep-alive procedure. (4) Step 4: The timer for the keep-alive procedure expires. The relay UE is triggered to report an indication to the BS, for example via a SidelinkUEInformation message. ● The timer for the keep-alive procedure expires. The relay UE may be triggered to report failure information to the BS after the timer for the keep-alive procedure expires. Then, the BS may stop transmitting data to UE1. - The relay UE may be triggered to report failure information to the BS based on one of the following conditions: 1. Expiration of a timer for the keep-alive procedure, 2. The AS layer of the relay UE receives a PC5-S link failure from the PC5-S layer of the relay UE, and 3. The relay UE declares sidelink RLF due to detecting PC5-S link failure. The reported failure information may be a sidelink failure notification, which may include a cause, e.g. "PC5 link failure" or "expiration of timer for keep-alive procedures".

[0102] FIG. 10 illustrates a simplified block diagram of an apparatus for fault handling procedures according to some embodiments of the present application.

[0103] In some embodiments of the present application, the apparatus 1000 may be a UE (e.g., a UE 101 as illustrated and shown in FIG. 1, a UE 201-C as illustrated and shown in FIG. 2, a UE 310 as illustrated and shown in FIG. 3, or a UE 410 as illustrated and shown in FIG. 4) and may be capable of at least performing the method illustrated in FIG. 7 or FIG. 8.

[0104] In some other embodiments of the present application, the apparatus 1000 may be a relay UE (e.g., relay UE 103 as illustrated and shown in FIG. 1, UE 201-A or UE 201-B as illustrated and shown in FIG. 2, or UE 320 as illustrated and shown in FIG. 3) and may perform at least the method illustrated in FIG. 6 or 9. In some additional embodiments of the present application, the apparatus 1000 may be a BS (e.g., BS 102 as illustrated and shown in FIG. 1 or BS 420 as illustrated and shown in FIG. 4).

[0105] As shown in FIG. 10, the apparatus 1000 may include at least one receiver 1002, at least one transmitter 1004, at least one non-transitory computer-readable medium 1006, and at least one processor 1008 coupled to the at least one receiver 1002, the at least one transmitter 1004, and the at least one non-transitory computer-readable medium 1006.

[0106] 10, elements such as at least one receiver 1002, at least one transmitter 1004, at least one non-transitory computer-readable medium 1006, and at least one processor 1008 are described in the singular, but the plural is contemplated unless limitation to the singular is expressly stated. In some embodiments of the present application, the at least one receiver 1002 and the at least one transmitter 1004 are combined into a single device, such as a transceiver. In some embodiments of the present application, the apparatus 1000 may further include an input device, a memory, and / or other components.

[0107] In some embodiments of the present application, at least one non-transitory computer-readable medium 1006 may store computer-executable instructions programmed to implement operations of a method, such as those described with reference to any one of Figures 6-9, by at least one receiver 1002, at least one transmitter 1004, and at least one processor 1008.

[0108] Those skilled in the art will understand that the operations of the methods described in connection with the embodiments disclosed herein may be embodied directly in hardware, in software modules executed by a processor, or in a combination of the two. The software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of known storage medium. Additionally, in some embodiments, the operations of the methods may reside as one or any combination or set of codes and / or instructions on a non-transitory computer-readable medium and may be incorporated into a computer program product.

[0109] Although the present disclosure has been described with its specific embodiments, it is apparent that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be exchanged, added, or substituted in other embodiments. Also, not all elements in each figure are necessary for the operation of the disclosed embodiments. For example, a person skilled in the art will be enabled to make and use the teachings of the present disclosure by simply utilizing the elements of the independent claims. Thus, the embodiments of the present disclosure described herein are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0110] In this document, the terms "comprise", "comprising" or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a set of elements does not include only those elements, but may include other elements not specified or inherent to such process, method, article, or apparatus. An element preceded by "a", "an", etc., does not, without further constraints, preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element. Also, the term "another" is defined as at least a second or more. The terms "having" and the like, as used herein, are defined as "comprising". [Explanation of symbols]

[0111] 100 Wireless communication system 101UE 101a UE 101b UE 102 BS 103 Relay UE 201-A UE 201-B UE 201-C UE 202 gNB 203 ng-eNB 310UE 320UE 410UE 420BS 1000 devices 1002 Receiver 1004 Transmitter 1006 Non-transitory computer readable medium 1008 Processor T301 Timer T304 Timer T316 Timer T400 Timer

Claims

1. Memory, a processor coupled to the memory, the processor comprising: Establishing a Uu Radio Resource Control (RRC) connection of a link between the device and a base station (BS); establishing a PC5 RRC connection of a link between a first user equipment (UE) and the device; sending a notification to the first UE, the notification comprising: Radio Link Failure (RLF) of the link between the device and the BS; RLF recovery failure of the link between the device and the BS; or Associating the RLF recovery success of the link between the device and the BS with at least the RLF of the link between the device and the BS. and causing the device to: The sending of the notification associated with the RLF of the link between the device and the BS is a transmission for suspending a Data Radio Bearer (DRB) destined for at least the BS to the first UE. Device.

2. A memory; a processor coupled to the memory, the processor comprising: Establishing a Uu Radio Resource Control (RRC) connection of a link between the device and a base station (BS); Establishing a PC5 RRC connection of a link between a first user equipment (UE) and the device; sending a notification to the first UE, the notification comprising: Radio Link Failure (RLF) of the link between the device and the BS; RLF recovery failure of the link between the device and the BS; or Associating the RLF recovery success of the link between the device and the BS with at least the RLF of the link between the device and the BS. and causing the device to: The sending of the notification associated with the RLF of the link between at least the device and the BS is a transmission to cause the first UE to initiate a relay discovery procedure. Device.

3. The notification includes an RLF notification, the RLF notification comprising: detecting an RLF on the link between the device and the BS; the device has performed a fast master cell group (MCG) link recovery procedure on the link between the device and the BS; or The apparatus of claim 1 or 2, wherein the notification is sent from the apparatus in response to at least one of the apparatus performing an RRC re-establishment procedure on the link between the apparatus and the BS.

4. The notification includes a recovery success notification, the recovery success notification comprising: Successfully completing a fast master cell group (MCG) link recovery procedure on the link between the device and the BS; or 3. The apparatus of claim 1 or 2, transmitted from the apparatus in response to at least one of successfully completing an RRC re-establishment procedure on the link between the apparatus and the BS.

5. The notification includes a recovery failure notification, the recovery failure notification comprising: failure to complete an RRC re-establishment procedure on the link between the device and the BS; or The apparatus according to claim 1 or 2, wherein the RRC re-establishment request message is transmitted from the apparatus in response to at least one of the expiration of a timer for transmitting the RRC re-establishment request message.

6. The notification: Medium Access Control Control Element (MAC CE), RRC signaling, or The device according to claim 1 or 2, wherein the control packet data unit (PDU) is transmitted by at least one of the control packet data units (PDUs) in an adaptation layer of the device.

7. The method of claim 6, wherein the sending of the notification associated with the RLF of the link between the device and the BS comprises: continuing to transmit data to the device that is terminated at the device; and continuing to receive data from the device; and is a transmission for causing the first UE to 3. Apparatus according to claim 1 or 2.

8. Memory, a processor coupled to the memory, the processor comprising: establishing a PC5 radio resource control (RRC) connection for a link between the device and a relay user equipment (UE), where a Uu RRC connection for a link between the relay UE and a base station (BS) is established; receiving a notification from one of the BS or the relay UE; and causing the device to: the notification received from the BS includes a request to perform a relay reselection procedure; The notification received from the relay UE, a Radio Link Failure (RLF) of the link between the relay UE and the BS; RLF recovery failure of the link between the relay UE and the BS; or The RLF recovery success of the link between the relay UE and the BS is associated with at least the RLF of the link between the device and the BS; In response to receiving the notification associated with the RLF, the processor is configured to suspend a data radio bearer (DRB) destined for at least the BS for the device. Device.

9. A memory; a processor coupled to the memory, the processor comprising: Establishing a PC5 Radio Resource Control (RRC) connection of a link between the device and a relay UE, where a Uu RRC connection of a link between the relay UE and a base station (BS) is established; receiving a notification from one of the BS or the relay UE; and causing the device to: the notification received from the BS includes a request to perform a relay reselection procedure; The notification received from the relay UE, a Radio Link Failure (RLF) of the link between the relay UE and the BS; RLF recovery failure of the link between the relay UE and the BS; or Associated with at least the RLF of the RLF recovery success of the link between the relay UE and the BS; In response to receiving the notification associated with the RLF of the link between the relay UE and the BS, the processor is configured to cause the device to initiate a relay discovery procedure. Device.

10. The notification includes an RLF notification sent from the relay UE, and the RLF notification comprises: the relay UE detects an RLF on the link between the relay UE and the BS; the relay UE has performed a fast master cell group (MCG) link recovery procedure on the link between the relay UE and the BS; or The apparatus of claim 8 or 9, wherein the relay UE is sent in response to at least one of the relay UE performing an RRC re-establishment procedure on the link between the relay UE and the BS.

11. The notification includes a recovery success notification, the recovery success notification comprising: the relay UE has successfully completed a fast MCG link recovery procedure on the link between the relay UE and the BS; or The apparatus of claim 8 or 9, wherein the relay UE is sent in response to at least one of the relay UE successfully completing an RRC re-establishment procedure on the link between the relay UE and the BS.

12. The notification includes a recovery failure notification, the recovery failure notification comprising: the relay UE fails to complete an RRC re-establishment procedure on the link between the relay UE and the BS; or The apparatus according to claim 8 or 9, wherein the RRC re-establishment request message is transmitted from the relay UE in response to at least one of expiry of a timer for transmission of the RRC re-establishment request message.

13. The notification: Medium Access Control Control Element (MAC CE), RRC signaling, or The apparatus according to claim 8 or 9, wherein the control packet data unit (PDU) is transmitted by at least one of the control packet data units (PDUs) in an adaptation layer of the relay UE.

14. The processor further comprises: A Radio Link Failure (RLF) of the link between the relay UE and the BS; or after receiving a notification associated with at least one of an RLF recovery failure of the link between the relay UE and the BS; 10. Apparatus according to claim 8 or 9, configured to cause the apparatus to

15. In response to receiving the notification associated with the RLF of the link between the relay UE and the BS, the processor: transmitting data addressed to said BS; or transmitting signaling addressed to said BS; 10. The apparatus according to claim 8 or 9, configured to interrupt at least one of the following for the apparatus:

16. In response to receiving the notification associated with at least the RLF of the link between the relay UE and the BS of the RLF of the link between the relay UE and the BS or the RLF recovery failure of the link between the relay UE and the BS, the processor:

10. The apparatus of claim 8 or 9, configured to cause the apparatus to initiate a relay reselection procedure.

17. The processor, sending an indication by an access stratum (AS) layer of the device to a PC5-S layer of the device, the indication indicating an occurrence of a failure in the link between the relay UE and the BS; sending a discovery message by the PC5-S layer of the device to the AS layer of the device; 10. The apparatus of claim 8 or 9, configured to cause the apparatus to:

18. In response to receiving the notification associated with the RLF of the link between the relay UE and the BS, the processor: continuing to transmit data terminated at the relay UE to the relay UE; and continuing to receive data from the relay UE; 10. The apparatus of claim 8 or 9, configured to cause the apparatus to:

19. A method performed by an apparatus, comprising: establishing a Uu Radio Resource Control (RRC) connection for a link between the device and a base station (BS); establishing a PC5 radio resource control (RRC) connection of a link between a first user equipment (UE) and the device; sending a notification to the first UE, the notification comprising: Radio Link Failure (RLF) of the link between the device and the BS; RLF recovery failure of the link between the device and the BS; or Successful RLF recovery of the link between the device and the BS and a step of: The step of sending the notification associated with the RLF of the link between the device and the BS is a step for causing the first UE to suspend at least a Data Radio Bearer (DRB) destined for the BS. method.

20. A method performed by an apparatus, comprising: establishing a Uu Radio Resource Control (RRC) connection for a link between the device and a base station (BS); establishing a PC5 radio resource control (RRC) connection for a link between a first user equipment (UE) and the device; sending a notification to the first UE, the notification comprising: Radio Link Failure (RLF) of the link between the device and the BS; RLF recovery failure of the link between the device and the BS; or Successful RLF recovery of the link between the device and the BS and a step of: The step of transmitting the notification associated with the RLF of the link between the device and the BS is for causing the first UE to initiate a relay discovery procedure. method.

21. the notification includes an RLF notification; detecting an RLF on the link between the device and the BS; the device has performed a fast master cell group (MCG) link recovery procedure on the link between the device and the BS; or the device has performed an RRC re-establishment procedure on the link between the device and the BS; 21. The method of claim 19 or 20, wherein the RLF notification is sent from the device in response to at least one of:

22. the notification includes a successful recovery notification; Successfully completing a high-speed master cell group (MCG) link recovery procedure on the link between the device and the BS; or Successfully completing an RRC re-establishment procedure on the link between the device and the BS.

21. The method of claim 19 or 20, wherein the successful recovery notification is sent from the device in response to at least one of the following:

23. the notification includes a recovery failure notification; failure of the device to complete an RRC re-establishment procedure on the link between the device and the BS; or Expiration of the timer for sending the RRC re-establishment request message 21. The method of claim 19 or 20, wherein the recovery failure notification is sent from the device in response to at least one of the following:

24. The notification: Medium Access Control Control Element (MAC CE), RRC signaling, or A control packet data unit (PDU) in an adaptation layer of the device The method according to claim 19 or 20, wherein the method is transmitted by at least one of the following:

25. The step of transmitting the notification associated with the RLF of the link between the device and the BS, comprising: continuing to transmit data terminated at the device to the device; continuing to receive data from the device; is a transmission for causing the first UE to 21. The method according to claim 19 or 20.

Images