Method and apparatus for failure handling procedures in a sidelink relay system - Patents.com

Abstract

[0003] An embodiment of the present application relates to a method and apparatus for a failure handling procedure in a sidelink relay system under Third Generation Partnership Project (3GPP) 5G New Radio (NR). According to one embodiment of the present application, the method includes the steps of: establishing a PC5 Radio Resource Control (RRC) connection for a link between a user equipment (UE) and a relay UE, where the PC5 RRC connection for a link between the relay UE and another UE is established; receiving a failure notification from the relay UE, where the failure notification indicates the occurrence of a failure on the link between the relay UE and the other UE; monitoring a discovery resource pool in response to receiving the failure notification from the relay UE; and reporting failure information associated with the relay connection to a base station (BS).

Description

[Technical field]

[0001] FIELD Embodiments of the present application relate generally to wireless communication technologies, and more particularly to a method and apparatus for failure handling procedures in a sidelink relay system. [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 Long Term Evolution (LTE) feature 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 user equipment (UE) located in the coverage or far from the BS, which may lead to 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, the details of how to provide failure handling procedures in sidelink relay systems have not yet been specifically discussed. Summary of the Invention [Means for solving the problem]

[0005] Some embodiments of the present application provide a method for wireless communication, which may be performed by a UE, including: establishing a PC5 Radio Resource Control (RRC) connection of a link between the UE and a relay UE, where the PC5 RRC connection of a link between the relay UE and another UE is established; and receiving a failure notification from the relay UE, where the failure notification indicates an occurrence of a failure on a link between the relay UE and the other UE.

[0006] Some embodiments of the present application also provide an apparatus for wireless communications, the apparatus including a non-transitory computer-readable medium storing computer-executable instructions, 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 the above-mentioned method for receiving a failure notification made by a UE.

[0007] Some embodiments of the present application provide a further method for wireless communication, which may be performed by a relay UE, including the steps of: detecting whether a failure occurs on a link between the relay UE and another UE, where a PC5 RRC connection of the link between the UE and the relay UE is established and a PC5 RRC connection of the link between the relay UE and the other UE is established; and in response to detecting that a failure occurs on the link between the relay UE and the other UE, sending a failure notification to the UE, where the failure notification indicates the occurrence of a failure on the link between the relay UE and the other 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 the above-mentioned further method for transmitting a failure notification made 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: sending an RRC reconfiguration message for a relay side link to a relay UE, where an RRC relay connection of a link between the UE and another UE is established, starting a timer for controlling the reconfiguration procedure, and reporting failure information to a BS in response to expiration of the timer or in response to receiving an RRC reconfiguration failure message for the relay side link from the relay UE, where the failure information indicates a failure on the RRC relay connection of the link between the UE and the aforementioned another UE.

[0010] Some embodiments of the present application also provide an apparatus for wireless communications that includes a non-transitory computer-readable medium having computer-executable instructions stored thereon, receiving circuitry, 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 the above-mentioned further method for reporting fault information performed by a UE.

[0011] Some embodiments of the present application provide a further method for wireless communication, which may be performed by a relay UE, including receiving an RRC reconfiguration message for a relay sidelink from the UE, starting a timer for controlling the reconfiguration procedure, and sending an RRC reconfiguration failure message for the relay sidelink to the UE in response to receiving an RRC reconfiguration failure sidelink message from another UE.

[0012] Some embodiments of the present application also provide an apparatus for wireless communications that includes a non-transitory computer-readable medium having computer-executable instructions stored thereon, receiving circuitry, 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 the above-mentioned further method for transmitting an RRC reconfiguration failure message for a relay sidelink performed by a relay UE.

[0013] 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.

[0014] 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]

[0015] [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 example flowchart of a sidelink RRC reconfiguration procedure in accordance with some embodiments of the present application. [Diagram 3] 1 is an example flowchart of a sidelink UE information procedure in accordance with some embodiments of the present application. [Figure 4] 1 is a flowchart of a method for receiving a fault notification according to some embodiments of the present application. [Diagram 5] 1 is a flowchart of a method for sending a fault notification according to some embodiments of the present application. [Figure 6] 4 is a flowchart of a method for reporting fault information according to some embodiments of the present application. [Figure 7] 1 is a flowchart of a method for transmitting an RRC reconfiguration failure message for a relay sidelink according to some embodiments of the present application. [Figure 8] 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

[0016] 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.

[0017] 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.

[0018] FIG. 1 illustrates a schematic diagram of a wireless communication system in accordance with some embodiments of the present application.

[0019] 1, the wireless communication system 100 includes, for illustrative purposes, two UEs (i.e., UE 101a and UE 101b), a BS 102, and a relay UE 103. 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.

[0020] Due to the long distance between UE 101a and UE 101b, these two UEs communicate with each other via relay UE 103. UE 101a and UE 101b may be connected to relay UE 103 via a network interface, e.g., a PC5 interface as defined in 3GPP standard documents. UE 101a may be connected to BS 102 via a network interface, e.g., a Uu interface as defined in 3GPP standard documents. Referring to FIG. 1, UE 101a is connected to relay UE 103 via PC5 link 1, UE 101b is connected to relay UE 103 via PC5 link 2, and UE 101a is connected to BS 102 via a Uu link.

[0021] In some embodiments of the present application, the UE 101a, UE 101b 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.

[0022] In some further embodiments of the present application, the UE 101a, UE 101b or relay UE 103 may include a portable wireless communication 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.

[0023] In some other embodiments of the present application, the UE 101a, UE 101b, 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 101a, UE 101b, or relay UE 103 may be referred to as a subscriber unit, mobile, mobile station, user, terminal, mobile terminal, wireless terminal, fixed terminal, subscriber station, user terminal or device, or described using other technical terms used in the art.

[0024] 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.

[0025] 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.

[0026] 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., UE 101a, UE 101b, or other similar UE) 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.

[0027] 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.

[0028] 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.

[0029] FIG. 2 illustrates an example flow chart of a sidelink RRC reconfiguration procedure in accordance with some embodiments of the present application.

[0030] As shown in FIG. 2, in step 201, UE(a) (e.g., UE 101a or UE 101b as illustrated and shown in FIG. 1) initiates a sidelink RRC reconfiguration procedure for UE(b) (e.g., UE 101b or UE 101a as illustrated and shown in FIG. 1) by sending an RRCReconfigurationSidelink message to UE(b).

[0031] If the sidelink RRC reconfiguration procedure is completed successfully, then UE(b) may send an "RRC reconfiguration complete sidelink message", e.g. an RRCReconfigurationCompleteSidelink message as defined in the 3GPP standard documents, to UE(a) in step 202. Alternatively, if the sidelink RRC reconfiguration procedure is not completed successfully, then UE(b) may send an "RRC reconfiguration failure sidelink message", e.g. an RRCReconfigurationFailureSidelink message as defined in the 3GPP standard documents, to UE(a) in step 202.

[0032] 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.

[0033] A UE (e.g., UE(a) as illustrated and depicted in FIG. 2) 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 (b) as illustrated and depicted in FIG. 2 ); - 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.

[0034] 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., timer T400 expiration) or a sidelink RRC reconfiguration failure has been declared.

[0035] The following table shows an implementation of timer T400 as specified in the 3GPP standard documents, including start conditions, stop conditions, action on expiration and possible common names for the timer.

[0036] [Table 1]

[0037] FIG. 3 illustrates an example flowchart of a sidelink UE information procedure in accordance with some embodiments of the present application.

[0038] As illustrated in Fig. 3, in step 301, a UE (e.g., UE 101a or UE 101b as illustrated and shown in Fig. 1 or UE(a) as illustrated and shown in Fig. 2) sends a "sidelink UE information NR message", e.g., a SidelinkUEinformationNR message as defined in a 3GPP standard document, to a BS (e.g., 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 identity (ID) and a sidelink failure cause.

[0039] At present, details on how to provide a failure handling procedure in a sidelink relay system under 3GPP 5G NR have not yet been specifically discussed. An embodiment of the present application provides a failure handling procedure in a sidelink relay system, for example, whether a relay UE reports a failure notification to a UE when an RLF of a link between the relay UE and another UE occurs or when the relay UE receives an RRCReconfigurationFailureSidelink message from another UE. Further details will be illustrated in the following text in combination with the accompanying drawings.

[0040] 4 illustrates a flowchart of a method for receiving a failure notification according to some embodiments of the present application. The method may be performed by a UE (e.g., a UE 101a or a UE 101b as illustrated and shown in FIG. 1, a UE (a) as illustrated and shown in FIG. 2, or a UE as illustrated and shown in FIG. 3). 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. 4.

[0041] In an exemplary method 400 as illustrated in Figure 4, a UE (e.g., UE 101a illustrated and shown in Figure 1) establishes a PC5 RRC connection for a link between the UE and a relay UE (e.g., relay UE 103 illustrated and shown in Figure 1) in operation 401. The embodiment of Figure 4 assumes that a PC5 RRC connection for a link between the relay UE and another UE (e.g., UE 101b illustrated and shown in Figure 1) has been established.

[0042] In one example, the UE further establishes an RRC relay connection of a link between the UE and the other UE. The RRC relay connection of a link is a logical link, and may also be named an "end-to-end link" between the UE and the other UE.

[0043] In operation 402, the UE receives a failure notification from a relay UE. The failure notification indicates the occurrence of a failure on a link between the relay UE and the other UE. The failure notification may be included in RRC signaling, a control packet data unit (PDU) at a Sidelink Adaptation Protocol (SLAP) layer, and a MAC Control Element (CE).

[0044] In one embodiment, the failure notification includes the ID of the other UE mentioned above, which may also be named a destination ID. For example, referring to FIG. 1, the failure notification may include: Once an end-to-end link between UE 101a and UE 101b is established, the destination ID associated with the end-to-end link, or Includes a destination ID associated with the link between the relay UE 103 and the UE 101b.

[0045] In a further embodiment, the failure notification includes a failure cause. The failure cause may be "sidelink radio link failure (RLF)" or "configuration failure". For example, RLF is included in the failure notification for a sidelink RLF and configuration failure is included in the failure notification for a sidelink RRC reconfiguration failure. The failure notification may include ● the maximum number of retransmissions of the RLC entity of the relay UE has been reached; expiry of a timer for transmission of an RRC reconfiguration for the sidelink (e.g. timer T400); The maximum number of consecutive Hybrid Automatic Repeat Request (HARQ) discontinuous transmissions (DTX) has been reached, and ● May further include at least one failure cause of the integrity check failure.

[0046] According to some embodiments, the UE further declares a sidelink RLF for a link between the UE and the relay UE. Once an RRC relay connection for a link between the UE and said other UE is established, the UE may further declare a sidelink RLF for a link between the UE and said other UE.

[0047] According to some embodiments, the UE further releases the DRB and the signaling radio bearer (SRB) of the link between the UE and the relay UE, and discards the sidelink communication configuration information of the link between the UE and the relay UE. Once the RRC relay connection of the link between the UE and the other UE is established, the UE may further release the DRB and the SRB of the link between the UE and the other UE, and the UE may further discard the sidelink communication configuration information of the link between the UE and the other UE.

[0048] According to some embodiments, the UE further comprises: resetting sidelink-specific Medium Access Control (MAC) configuration information for the link between the UE and the relay UE; setting the connection state of the link between the UE and the relay UE to a released state; and ●Indicate to the upper layers of the other UE mentioned above that the “link between the UE and the relay UE is in a released state”.

[0049] Once the RRC relay connection of the link between the UE and the another UE is established, the UE further comprises: resetting sidelink specific MAC configuration information of a link between the UE and said other UE; setting a connection state of a link between the UE and said other UE to a released state; and ● It may indicate to the upper layers of said other UE the release status of the link between the UE and said other UE.

[0050] According to some embodiments, the UE further determines whether the UE is within the coverage of a BS (e.g., BS 102 illustrated and shown in FIG. 1). If the UE determines that the UE is within the coverage of the BS, the UE may report failure information to the BS in response to receiving the failure notification. The failure information is associated with the received failure notification.

[0051] For example, the fault information may include a link status between the UE and the relay UE, and a link status between the relay UE and the other UE. The link status between the UE and the relay UE may indicate "RLF occurrence" or "link is available". Similarly, the link status between the relay UE and the other UE may indicate "RLF occurrence" or "link is available".

[0052] According to some embodiments, the UE further receives an RRC reconfiguration message from the BS and performs a relay reselection procedure. The RRC reconfiguration message instructs the UE to perform a relay reselection procedure. According to some other embodiments, the UE performs a relay reselection procedure in response to receiving the failure notification.

[0053] During the relay reselection procedure, the UE monitors the discovery resource pool to find one or more relay UEs, and selects one relay UE among the found one or more relay UEs. The UE may further establish a PC5 RRC connection for the link between the UE and the selected relay UE.

[0054] Details described in all other embodiments of the present application (e.g. details of how to handle failures on the link between the relay UE and the UE) are applicable to the embodiment of Fig. 4. Moreover, details described in the embodiment of Fig. 4 are applicable to all embodiments of Figs. 1-3 and 5-8.

[0055] 5 illustrates a flowchart of a method for sending a failure notification according to some embodiments of the present application. The method may be performed by a relay UE (e.g., the relay UE 103 illustrated and shown in FIG. 1). 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. 5.

[0056] In an exemplary method 500 as illustrated in FIG. 5, a PC5 RRC connection of a link between a UE (e.g., UE 101a illustrated and illustrated in FIG. 1) and a relay UE (e.g., relay UE 103 illustrated and illustrated in FIG. 1) is established, and a PC5 RRC connection of a link between the relay UE and another UE (e.g., UE 101b illustrated and illustrated in FIG. 1) is established. In operation 501, the relay UE detects whether a failure occurs on the link between the relay UE and the above-mentioned other UE. In operation 502, if the relay UE detects that a failure occurs on the link between the relay UE and the above-mentioned other UE, the relay UE sends a failure notification to the UE to indicate the occurrence of a failure on the link between the relay UE and the above-mentioned other UE.

[0057] In one example, the failure is a sidelink RLF of a link between the relay UE and said other UE. In a further example, the failure is a failure during an RRC reconfiguration procedure between the relay UE and said other UE, and the failure indication is an "RRC Reconfiguration Failure for Relay Sidelink message".

[0058] The fault notification in the embodiment of Figure 5 may be of similar format or content to those of the fault notification in the embodiment of Figure 4. For example, similar to the embodiment of Figure 4, in the embodiment of Figure 5 the fault notification includes the fault cause, e.g., sidelink RLF or configuration failure.

[0059] According to some embodiments, the failure notification in the embodiment of Figure 5 includes the ID of the other UE as mentioned above, which may also be named a destination ID. For example, referring to Figure 1, the failure notification includes a destination ID associated with the link between the relay UE 103 and the UE 101b, or, if an end-to-end link between the UE 101a and the UE 101b is established, a destination ID associated with the end-to-end link.

[0060] Details described in all other embodiments of the present application (e.g. details of how to handle failures on the link between the relay UE and the UE) are applicable to the embodiment of Fig. 5. Moreover, details described in the embodiment of Fig. 5 are applicable to all embodiments of Figs. 1-4 and 6-8.

[0061] The following text describes specific embodiments 1 and 2 of the method as depicted and illustrated in FIGS.

[0062] EMBODIMENT 1 According to embodiment 1, a UE (e.g., UE 101a as shown and illustrated in FIG. 1 ), a relay UE (e.g., relay UE 103 as shown and illustrated in FIG. 1 ), and another UE (e.g., UE 101b as shown and illustrated in FIG. 1 ) perform the following steps: (1) A PC5 RRC connection is established for PC5 link 1 between UE 101a and relay UE 103. Another PC5 RRC connection is established for PC5 link 2 between relay UE 103 and UE 101b. (2) Optionally, an RRC relay connection between UE 101a and UE 101b is established, where the expression “optionally” means that this step is optional and may not be performed in some embodiments. The UE 101a sends an “RRC reconfiguration message for relay sidelink” to the UE 101b, and the message is relayed by the relay UE 103. The “RRC reconfiguration message for relay sidelink” may also be named “RRC reconfiguration message for sidelink relay”, “RRC reconfiguration message for sidelink relay connection”, “RRC reconfiguration message for relay sidelink connection”, etc. The UE 101b sends an “RRC reconfiguration complete message for relay sidelink” to the UE 101a, and the message is relayed by the relay UE 103. The “RRC reconfiguration complete message for relay sidelink” may also be named “RRC reconfiguration complete message for sidelink relay”, etc. (3) There may be the following possible steps of the relay UE 103: Step (3a): The relay UE 103 declares a sidelink RLF for the link between the relay UE 103 and the UE 101b when the following condition occurs: ≫Trigger conditions for sending a fault notification with the fault cause "Sidelink RLF": a) upon an indication from the sidelink RLC entity of the relay UE 103 that the maximum number of retransmissions for a particular destination (i.e., the UE 101b) has been reached, or b) upon expiry of timer T400, or c) upon indication from the sidelink MAC entity of the relay UE 103 that a maximum number of consecutive HARQ DTXs for a particular destination has been reached, or d) In response to an integrity check failure indication from the sidelink PDCP entity of the relay UE 103. ● Step (3b): After the relay UE 103 sends an RRCReconfigurationSidelink message to the UE 101b, the relay UE 103 receives an RRCReconfigurationFailureSidelink message. ≫Trigger conditions for sending a notification with the cause of the problem being "Configuration Error": a) In response to receiving an RRCReconfigurationFailureSidelink message from the UE 101b. (4) When the relay UE 103 declares a sidelink RLF or when the relay UE 103 detects a configuration failure, the relay UE 103 sends a failure notification to the UE 101a. When an RLF occurs in the link between the relay UE 103 and the UE 101b or when the relay UE 103 receives an RRC reconfiguration failure message from the UE 101b, the relay UE 103 reports a failure notification to the UE 101a. The following information should be added to the problem notification: ≫A destination ID associated with the link between UE 101a and UE 101b, or a destination ID associated with the link between relay UE 103 and UE 101b. ≫Cause of fault: Sidelink RLF or configuration fault. >>Optionally, the following further information can be added to the failure notification: RLC max number of retransmissions, T400 expiry, max number of consecutive HARQ DTX, or integrity check failure. Here, the expression "optionally" means that this further information is optional and may not be included in some embodiments. (5) The UE 101a receives a failure notification from the relay UE 103. The failure information may indicate "Sidelink RLF" or "Configuration Failure". If the received failure notification indicates a sidelink RLF between the relay UE 103 and the UE 101b, the UE 101a may take the following actions: » UE 101a declares a sidelink RLF for the link between UE 101a and UE 101b; » The UE 101a declares a sidelink RLF for the link between the UE 101a and the relay UE 103; » UE 101a releases the DRB and SRB of the link between UE 101a and UE 101b; » The UE 101a releases the DRB and SRB of the link between the UE 101a and the relay UE 103; » The UE 101a discards configuration information for NR sidelink communication of the link between the UE 101a and the UE 101b; » The UE 101a discards configuration information for NR sidelink communication of the link between the UE 101a and the relay UE 103; » The UE 101a resets the sidelink specific MAC of the link between the UE 101a and the UE 101b; » The UE 101a resets the sidelink specific MAC of the link between the UE 101a and the relay UE 103; » UE 101a considers the PC5 RRC connection of the link between UE 101a and UE 101b to be released; » The UE 101a considers the PC5 RRC connection of the link between the UE 101a and the relay UE 103 to be released; >>UE 101a indicates the released state of the PC5 RRC connection (ie, that the PC5 RRC connection is unavailable) to higher layers for UE 101b. (6) When the UE 101a receives the failure notification from the relay UE 103, the UE 101a may be triggered to send a Sidelink UE information message to the serving BS of the UE 101a (e.g., BS 102 as shown and illustrated in FIG. 1 ). Meanwhile, the UE 101a is triggered to monitor the discovery resource pool for the relay reselection procedure. Regarding whether UE 101a reports end-to-end relay connection failure information to the BS: The UE 101a receives fault information from the relay UE 103. The fault information includes the destination ID of the UE 101b, the cause of the fault, and the ID of the relay UE 103. >>New failure causes for this case could be reception of a sidelink RLF or reception of a configuration failure. The failure information includes the true destination ID associated with the multiple hops, for example the ID of the UE 101b. After the BS receives the failure information, the BS may reconfigure the UE 101a to perform a relay reselection procedure.

[0063] EMBODIMENT 2 Similar to embodiment 1, according to embodiment 2, a UE (e.g., UE 101a as shown and illustrated in FIG. 1), a relay UE (e.g., relay UE 103 as shown and illustrated in FIG. 1), and another UE (e.g., UE 101b as shown and illustrated in FIG. 1) perform the following steps. Steps (1) and (2) of embodiment 2 are the same as steps (1) and (2) of embodiment 1. (1) A PC5 RRC connection is established for PC5 link 1 between UE 101a and relay UE 103. Another PC5 RRC connection is established for PC5 link 2 between relay UE 103 and UE 101b. (2) Optionally, an RRC relay connection is established for the link between UE 101a and UE 101b, where the expression "optionally" means that this step is optional and may not be performed in some embodiments. (3) The UE 101a declares a sidelink RLF for the link between the UE 101a and the relay UE 103. Alternatively, the UE 101a sends an RRCReconfigurationSidelink message to the relay UE 103, and then the UE 101a receives an RRCReconfigurationFailureSidelink message from the relay UE 103. (4) The UE 101a is triggered to monitor the discovery resource pool for the relay reselection procedure.

[0064] 6 illustrates a flowchart of a method for reporting fault information according to some embodiments of the present application. The method may be performed by a UE (e.g., a UE 101a or a UE 101b as illustrated and shown in FIG. 1, a UE (a) as illustrated and shown in FIG. 2, or a UE as illustrated and shown in FIG. 3). 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. 6.

[0065] In an example method 600 as illustrated in Figure 6, an RRC relay connection for a link between a UE (e.g., UE 101a illustrated and illustrated in Figure 1) and another UE (e.g., UE 101b illustrated and illustrated in Figure 1) is established. In operation 601, the UE sends an "RRC Reconfiguration for Relay Sidelink Message" to a relay UE (e.g., relay UE 103 illustrated and illustrated in Figure 1).

[0066] In operation 602, the UE starts a timer for controlling the reconfiguration procedure. In operation 603, if the timer expires or the UE receives an RRC reconfiguration failure message for the relay side link from the relay UE, the UE reports failure information to a BS (e.g., BS 102 as illustrated and shown in FIG. 1). The failure information indicates a failure on the RRC relay connection of the link between the UE and the other UE mentioned above.

[0067] The fault information in the embodiment of Figure 6 is in the same format or content as those of the fault information in the embodiment of Figure 4. For example, similar to the embodiment of Figure 4, in the embodiment of Figure 6, the fault information may include the status of the link between the UE and the relay UE, and the status of the link between the relay UE and the other UE mentioned above. Each of the statuses may represent "RLF occurrence" or "link is available".

[0068] According to some embodiments, the UE receives an RRC reconfiguration message from the BS and performs a relay reselection procedure. The RRC reconfiguration message instructs the UE to perform a relay reselection procedure. According to some other embodiments, the UE performs the relay reselection procedure autonomously. For example, the UE performs the relay reselection procedure autonomously in response to reporting failure information to the BS. The relay reselection procedure in the embodiment of FIG. 6 is similar to that in the embodiment of FIG. 4.

[0069] In one example, the failure information includes the ID of the other UE mentioned above, which may also be named destination ID. For example, referring to FIG. 1, the failure information is: Once an end-to-end link between UE 101a and UE 101b is established, the destination ID associated with the end-to-end link, or Includes a destination ID associated with the link between the relay UE 103 and the UE 101b.

[0070] In one example, the failure information includes a failure cause. For example, the failure cause may be a sidelink RLF of an RRC relay connection of a link between the UE 101a and the UE 101b. The failure cause may be a configuration failure of an RRC relay connection of a link between the UE 101a and the UE 101b.

[0071] In one embodiment, a UE declares a sidelink RLF for a link between the UE and another UE as described above, for example, UE 101a declares a sidelink RLF for a link between UE 101a and UE 101b.

[0072] In a further embodiment, the UE further performs the following operations: Releasing the DRBs and SRBs of a link between the UE and said other UE; discarding sidelink communication configuration information of a link between the UE and said other UE; resetting sidelink specific MAC configuration information of a link between the UE and said other UE; Setting the "connection state" of the link between the UE and said other UE to a "released state"; and ●Indicating to the upper layer of the other UE mentioned above "the release state of the link between the UE and the other UE mentioned above."

[0073] Details described in all other embodiments of the present application (e.g. details of how to handle failures on the link between the relay UE and the 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, 7 and 8.

[0074] 7 illustrates a flowchart of a method for transmitting an RRC reconfiguration failure message for a relay sidelink according to some embodiments of the present application. The method may be performed by a relay UE (e.g., the relay UE 103 illustrated and shown in FIG. 1). 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. 7.

[0075] In an exemplary method 700 as illustrated in FIG. 7, in operation 701, a relay UE (e.g., relay UE 103 illustrated and shown in FIG. 1) receives an “RRC reconfiguration for relay sidelink message” from a UE (e.g., UE 101a illustrated and shown in FIG. 1). In operation 702, the relay UE starts a timer for controlling the reconfiguration procedure. In operation 703, if the relay UE receives an RRC reconfiguration failure sidelink message from another UE (e.g., UE 101b illustrated and shown in FIG. 1), the relay UE sends an “RRC reconfiguration failure for relay sidelink message” to the UE.

[0076] In one embodiment, the relay UE further sends an "RRC reconfiguration message for relay side link" to the other UE. For example, the "RRC reconfiguration failure message for relay side link" includes an ID of the other UE, which may also be named a destination ID. With reference to FIG. 1, the "RRC reconfiguration failure message for relay side link" may include a destination ID associated with the link between the relay UE 103 and the UE 101b, or a destination ID associated with the end-to-end link between the UE 101a and the UE 101b if an end-to-end link between them is established.

[0077] In one example, the “RRC Reconfiguration Failure Message for Relay Sidelink” includes a failure cause. Similar to the failure cause in the failure notification of the embodiments of Figures 4-6, the failure cause in the “RRC Reconfiguration Failure Message for Relay Sidelink” includes a sidelink RLF or configuration failure.

[0078] Details described in all other embodiments of the present application (e.g. details of how to handle failures on the link between the relay UE and the 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.

[0079] The following text describes a specific embodiment 3 of the method as depicted and illustrated in FIGS.

[0080] EMBODIMENT 3 According to embodiment 3, a UE (e.g., a UE 101a as shown and illustrated in FIG. 1 ), a relay UE (e.g., a relay UE 103 as shown and illustrated in FIG. 1 ), and another UE (e.g., a UE 101b as shown and illustrated in FIG. 1 ) perform the following steps: (1) A PC5 RRC connection is established for PC5 link 1 between UE 101a and relay UE 103. Another PC5 RRC connection is established for PC5 link 2 between relay UE 103 and UE 101b. (2) Optionally, the UE 101a sends an “RRC Reconfiguration for Relay Sidelink Message” to the UE 101b via the relay UE 103. Here, the expression “optionally” means that this step is optional and may not be performed in some embodiments. a) In case 1-1: i. When the UE 101a sends the "RRC Reconfiguration for Relay Sidelink Message", the UE 101a starts a timer. The timer is used to control the RRC reconfiguration procedure. ii. The UE 101a reports failure information to the network or a BS (eg, the BS 102 as illustrated and shown in FIG. 1) upon expiration of this timer. b) In case 1-2: i. After the UE 101a sends an "RRC Reconfiguration for Relay Side Link message" to the UE 101b, the UE 101a receives an "RRC Reconfiguration Failure for Relay Side Link message". (3) The UE 101a may receive an “RRC Reconfiguration Failure for Relay Sidelink Message” from the UE 101b, and the message is relayed by the relay UE. Otherwise, a timer for controlling the RRC reconfiguration procedure may expire. (4) The UE 101a reports the fault information to the BS. a) The failure information may be included in the SidelinkUEInformation message. b) The fault information includes a destination ID (eg, the ID of the UE 101b), a fault cause, and an ID of the relay UE 103. i. New fault cause for case 1-1: Sidelink RLF on relay connection. ii. New cause of failure for Case 1-2: Relay connection configuration failure. c) The status of the link between the UE 101a and the relay UE 103 may also be included in the failure information and may be useful for the BS's decision. d) The status of the link between the relay UE 103 and the UE 101b may be included in the failure information. i. The UE 101a may report failure information to the relay UE 103. The relay UE 103 may respond to the UE 101a whether the link between the relay UE 103 and the UE 101b is available or not. e) The failure information includes the true destination associated with the multiple hops, for example the ID of the UE 101b. f) After the BS receives the failure information from the UE 101a, the BS may reconfigure the UE to perform a relay reselection procedure.

[0081] FIG. 8 illustrates a simplified block diagram of an apparatus for fault handling procedures according to some embodiments of the present application.

[0082] In some embodiments of the present application, the apparatus 800 may be a UE (e.g., UE 101a or UE 101b as illustrated and shown in FIG. 1, UE(a) as illustrated and shown in FIG. 2, or a UE as illustrated and shown in FIG. 3) and may be capable of at least performing the method illustrated in FIG. 4 or FIG. 6.

[0083] In some other embodiments of the present application, the apparatus 800 may be a relay UE (e.g., a relay UE 103 as illustrated and shown in FIG. 1 or a UE (b) as illustrated and shown in FIG. 2) and may perform at least the method illustrated in FIG. 5 or FIG. 7.

[0084] In some additional embodiments of the present application, the apparatus 800 may be a BS (e.g., the BS 102 as illustrated and shown in FIG. 1 or the BS as illustrated and shown in FIG. 3) and may perform at least some of the method steps as illustrated in any one of FIGS. 4-7.

[0085] As shown in FIG. 8, the apparatus 800 may include at least one receiver 802, at least one transmitter 804, at least one non-transitory computer-readable medium 806, and at least one processor 808 coupled to the at least one receiver 802, the at least one transmitter 804, and the at least one non-transitory computer-readable medium 806.

[0086] 8, elements such as at least one receiver 802, at least one transmitter 804, at least one non-transitory computer-readable medium 806, and at least one processor 808 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 802 and the at least one transmitter 804 are combined into a single device, such as a transceiver. In some embodiments of the present application, the apparatus 800 may further include an input device, a memory, and / or other components.

[0087] In some embodiments of the present application, at least one non-transitory computer-readable medium 806 may store computer-executable instructions programmed to implement operations of a method, such as those described with reference to any one of Figures 4-7, by at least one receiver 802, at least one transmitter 804, and at least one processor 808.

[0088] 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.

[0089] 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.

[0090] 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]

[0091] 100 Wireless communication system 101a UE 101b UE 102 BS 103 Relay UE 800 equipment 802 Receiver 804 Transmitter 806 Non-transitory computer-readable medium 808 Processor T400 Timer

Claims

1. 1. A method performed by a first user equipment (UE), comprising: establishing a first PC5 Radio Resource Control (RRC) connection of a link between the first UE and a relay UE, wherein a second PC5 RRC connection of a link between the relay UE and a second UE is established; receiving a failure notification from the relay UE, the failure notification indicating an occurrence of a failure on the link between the relay UE and the second UE; Including, The fault notification, In response to an RRC relay connection of a link between the first UE and the second UE being established, the RRC relay connection includes at least an identifier (ID) of the second UE associated with the RRC relay connection of the link between the first UE and the second UE. method.

2. establishing an RRC relay connection for a link between the first UE and the second UE; The method of claim 1, further comprising:

3. The fault notification, The method of claim 1 , further comprising: an ID of the second UE associated with the link between the relay UE and the second UE.

4. The fault notification includes a fault cause, and the fault cause is Sidelink Radio Link Failure (RLF); The method of claim 1 , further comprising one of a configuration failure and

5. The fault notification, a maximum number of retransmissions of the RLC entity of the relay UE has been reached; and expiry of a timer for transmission of an RRC reconfiguration for the sidelink; and The maximum number of consecutive Hybrid Automatic Repeat Request (HARQ) discontinuous transmissions (DTX) has been reached, The method of claim 4 , further comprising at least one failure cause associated with an integrity check failure.

6. declaring a sidelink RLF for the link between the first UE and the relay UE; or In response to an RRC relay connection being established for a link between the first UE and the second UE, declaring a sidelink RLF for the link between the first UE and the second UE. The method of claim 1, further comprising:

7. Releasing a Data Radio Bearer (DRB) and a Signaling Radio Bearer (SRB) of the link between the first UE and the relay UE; discarding sidelink communication configuration information of the link between the first UE and the relay UE; In response to an RRC relay connection being established for a link between the first UE and the second UE, Releasing a DRB and an SRB of the link between the first UE and the second UE; discarding sidelink communication configuration information of the link between the first UE and the second UE; The method of claim 1, further comprising:

8. resetting sidelink-specific Medium Access Control (MAC) configuration information of the link between the first UE and the relay UE; setting a connection state of the link between the first UE and the relay UE to a released state; indicating the release status of the link between the first UE and the relay UE to an upper layer of the second UE; In response to an RRC relay connection being established for a link between the first UE and the second UE, resetting sidelink-specific MAC configuration information of the link between the first UE and the second UE; setting a connection state of the link between the first UE and the second UE to a released state; indicating the release status of the link between the first UE and the second UE to the higher layer of the second UE; The method of claim 1, further comprising:

9. The fault notification, RRC signaling; A control packet data unit (PDU) at a Sidelink Adaptation Protocol (SLAP) layer; The method of claim 1 , which is included in one of a MAC Control Element (CE).

10. determining whether the first UE is within coverage of a base station (BS); in response to the first UE determining that it is within the coverage of the BS, reporting fault information to the BS in response to receiving the fault notification, the fault information being associated with the fault notification; The method of claim 1, further comprising:

11. The fault information is a state of the link between the first UE and the relay UE; and and a state of the link between the relay UE and the second UE.

12. The state of the link between the first UE and the relay UE or the state of the link between the relay UE and the second UE, The occurrence of RLF and The method of claim 11 , further comprising indicating one of that the link is available and that the link is not available.

13. receiving an RRC reconfiguration message from a BS, the RRC reconfiguration message instructing the first UE to perform a relay reselection procedure; performing the relay reselection procedure; The method of claim 1, further comprising:

14. performing a relay reselection procedure in response to receiving the failure notification. The method of claim 1, further comprising:

15. performing the relay reselection procedure, monitoring a discovery resource pool to discover one or more relay UEs; and selecting a relay UE from the one or more relay UEs.

16. establishing a PC5 RRC connection for a link between the first UE and the selected one relay UE; 16. The method of claim 15, further comprising:

17. A method performed by a relay user equipment (UE), comprising: detecting whether a failure occurs on a link between the relay UE and a second UE, where a first PC5 Radio Resource Control (RRC) connection of the link between a first UE and the relay UE is established, and a second PC5 RRC connection of the link between the relay UE and the second UE is established; in response to detecting that the failure occurs on the link between the relay UE and the second UE, sending a failure notification to the first UE, the failure notification indicating the occurrence of the failure on the link between the relay UE and the second UE; The fault notification, In response to an RRC relay connection of a link between the first UE and the second UE being established, the RRC relay connection includes at least an identifier (ID) of the second UE associated with the RRC relay connection of the link between the first UE and the second UE. method.

18. the failure on the link between the relay UE and the second UE, a sidelink Radio Link Failure (RLF) of the link between the relay UE and the second UE; and 18. The method of claim 17, wherein the failure is one of a failure during an RRC reconfiguration procedure between the relay UE and the second UE, and the failure notification is an RRC reconfiguration failure message for a relay sidelink.

19. The fault notification, The method of claim 17, further comprising: an ID of the second UE associated with the link between the relay UE and the second UE.

20. The fault notification includes a fault cause, and the fault cause is Side link RLF and 20. The method of claim 17, further comprising one of a configuration failure and

21. The fault notification, a maximum number of retransmissions of a radio link control (RLC) entity of the relay UE has been reached; and expiry of a timer for transmission of an RRC reconfiguration for the sidelink; and The maximum number of consecutive Hybrid Automatic Repeat Request (HARQ) discontinuous transmissions (DTX) has been reached, 21. The method of claim 20, further comprising at least one failure cause associated with an integrity check failure.

22. The fault notification, RRC signaling; A control packet data unit (PDU) at a Sidelink Adaptation Protocol (SLAP) layer; The method of claim 17, which is included in one with a MAC Control Element (CE).

23. at least one non-transitory computer-readable medium storing computer-executable instructions; at least one receiving circuitry; at least one transmission circuitry; at least one processor coupled to the at least one non-transitory computer readable medium, the at least one receiving circuitry, and the at least one transmitting circuitry; The computer executable instructions cause the at least one processor to implement a method according to any one of claims 1 to 16. Device.

24. at least one non-transitory computer-readable medium storing computer-executable instructions; at least one receiving circuitry; at least one transmission circuitry; at least one processor coupled to the at least one non-transitory computer readable medium, the at least one receiving circuitry, and the at least one transmitting circuitry; The computer executable instructions cause the at least one processor to implement a method according to any one of claims 17 to 22. Device.

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