Methods and apparatus for designing an adaptation layer and handling failures in a side link relay system

Abstract

Embodiments of the present application relate to methods and apparatuses for designing an adaptation layer and handling failures in a side-link relay system under the Third Generation Partnership Project (3GPP) 5G New Radio (NR). According to embodiments of the present application, a method may include: receiving a radio resource control (RRC) setup request from a user equipment (UE), wherein a PC5 RRC connection of a link between the UE and a relay UE has been established; transmitting the RRC setup request to a base station (BS), wherein an RRC connection of a link between the relay UE and the BS has been established; receiving response information from the BS, wherein the response information includes at least one of a cell radio network temporary identifier (C-RNTI) and an identifier (ID) of the UE; and transmitting the response information to the UE. After a relay connection of a link between the UE and the BS is established, a failure may occur. When a radio link failure (RLF) occurs between the relay UE and the BS, the relay UE needs to transmit a notification to the UE. In addition, when an RLF occurs between the relay UE and the UE, the relay UE needs to transmit a notification to the BS.

Description

Technical Field

[0001] Embodiments of the present application generally relate to wireless communication technologies, and more particularly, to methods and devices for designing an adaptation layer and handling failures in a sidelink relay system. Background Art

[0002] Vehicle-to-Everything (V2X) has been introduced into 5G wireless communication technologies. In terms of the channel structure of V2X communication, the direct link between two User Equipments (UEs) is called a sidelink. The sidelink is a Long-Term Evolution (LTE) feature introduced in the 12th version of 3GPP, and it enables direct communication between proximal UEs, and data does not need to pass through a Base Station (BS) or a core network.

[0003] In the 3rd Generation Partnership Project (3GPP), promoting the deployment of Relay Nodes (RNs) in wireless communication systems. One purpose of deploying RNs is to enhance the coverage area of the BS by improving the throughput of User Equipments (UEs) located within the coverage or far from the BS, which may result in relatively low signal quality. In some cases, an RN can also be called a relay UE. The 3GPP 5G sidelink system including a relay UE can be called a sidelink relay system.

[0004] Currently, in 3GPP 5G New Radio (NR) systems and the like, the details on how to design an adaptation layer and handle failures in a sidelink relay system have not been specifically discussed. Summary of the Invention

[0005] Some embodiments of the present application provide a method for wireless communication. The method can be executed by a relay UE. The method includes: receiving a Radio Resource Control (RRC) setup request from a UE, where the PC5 RRC connection of the link between the UE and the relay UE has been established; transmitting an RRC setup request to a BS, where the RRC connection of the link between the relay UE and the BS has been established; receiving response information from the BS, where the response information includes at least one of a Cell Radio Network Temporary Identifier (C-RNTI) and an identifier (ID) of the UE; and transmitting the response information to the UE.

[0006] Some embodiments of the present application also provide a device for wireless communication. The device includes: a non-transitory computer-readable medium storing computer-executable instructions; receiving circuitry; transmitting circuitry; and a processor coupled to the non-transitory computer-readable medium, the receiving circuitry, and the transmitting circuitry, where the computer-executable instructions cause the processor to implement the above method for receiving response information executed by a relay UE.

[0007] Some embodiments of the present application provide another method for wireless communication. The method may be performed by a BS. The method includes: receiving an RRC setup request from a relay UE, where a PC5 RRC connection of a link between the UE and the relay UE has been established, and where an RRC connection of a link between the relay UE and the BS has been established; and transmitting response information to the relay UE, where the response information includes at least one of a C-RNTI and an ID of the UE.

[0008] Some embodiments of the present application further provide a device for wireless communication. The device 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, where the computer-executable instructions cause the processor to implement the above method for transmitting response information performed by a BS.

[0009] Some embodiments of the present application provide another method for wireless communication. The method may be performed by a relay UE. The method includes: establishing a PC5 RRC connection of a link between the UE and the relay UE; establishing an RRC connection of a link between the relay UE and the BS; establishing a relay connection of a link between the UE and the BS; detecting whether a failure occurs on the link between the UE and the relay UE; and in response to detecting the failure on the link between the relay UE and the UE, transmitting failure information to the BS.

[0010] Some embodiments of the present application further provide a device for wireless communication. The device 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, where the computer-executable instructions cause the processor to implement the above method for transmitting failure information performed by a relay UE.

[0011] Some embodiments of the present application provide another method for wireless communication. The method may be performed by a relay UE. The method includes: establishing a relay logical connection of a link between the UE and the BS; detecting whether a failure occurs on the link between the relay UE and the BS, where a PC5 RRC connection of a link between the UE and the relay UE has been established, and where an RRC connection of a link between the relay UE and the BS has been established; and in response to detecting the failure on the link between the relay UE and the BS, transmitting a failure notification to the UE.

[0012] Some embodiments of the present application also provide a device for wireless communication. The device includes: a non-transitory computer-readable medium storing computer-executable instructions; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement the above method for transmission failure notification performed by a relay UE.

[0013] Some embodiments of the present application provide another method for wireless communication. The method may be performed by a UE. The method includes: receiving, from a relay UE, a notification associated with a failure, wherein a PC5 RRC connection of a link between the UE and the relay UE has been established, wherein an RRC connection of a link between the relay UE and a BS has been established, and wherein the notification associated with the failure indicates a failure on a link between the relay UE and the BS; and initiating a relay reselection process.

[0014] Some embodiments of the present application also provide a device for wireless communication. The device includes: a non-transitory computer-readable medium storing computer-executable instructions; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement the above method for initiating a relay reselection process performed by a UE.

[0015] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To describe the manner in which the advantages and features of the present application can be obtained, a description of the present application is presented by reference to specific embodiments of the application illustrated in the accompanying drawings. These drawings only depict example embodiments of the present application and should not be considered as limiting its scope.

[0017] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application;

[0018] Figure 2 A exemplary flowchart illustrating a sidelink RRC reconfiguration process according to some embodiments of the present application;

[0019] Figure 3 A exemplary flowchart illustrating a sidelink UE information process according to some embodiments of the present application;

[0020] Figure 4Illustrate an exemplary protocol stack with a sidelink adaptation protocol (SLAP) layer according to some embodiments of the present application;

[0021] Figure 5 Illustrate a flowchart of a method for receiving response information according to some embodiments of the present application;

[0022] Figure 6 Illustrate a flowchart of a method for transmitting response information according to some embodiments of the present application;

[0023] Figure 7 Illustrate a flowchart of a method for transmitting failure information according to some embodiments of the present application;

[0024] Figure 8 Illustrate a flowchart of a method for transmitting a failure notification according to some embodiments of the present application;

[0025] Figure 9 Illustrate a flowchart of a method for initiating a relay reselection process according to some embodiments of the present application; and

[0026] Figure 10 Illustrate a simplified block diagram of a device for a failure handling process according to some embodiments of the present application. Detailed Description of the Embodiments

[0027] The detailed description of the drawings is intended as a description of the preferred embodiments of the present application and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions can be implemented by different embodiments intended to be covered within the spirit and scope of the present application.

[0028] Now, reference will be made in detail to some embodiments of the present application, examples of which are illustrated in the drawings. For ease of understanding, the embodiments are provided in a specific network architecture and new service scenario, such as 3GPP 5G, 3GPP LTE Release 8, etc. It is contemplated that with the development of the network architecture and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and furthermore, the terms stated in the present application may change, which should not affect the principles of the present application.

[0029] Figure 1 Illustrate a schematic diagram of a wireless communication system according to some embodiments of the present application.

[0030] As Figure 1 shown, for illustrative purposes, the wireless communication system 100 includes a UE 101, a BS 102, and a relay UE 103. Although a specific number of UEs, relay UEs, and BSs are depicted in Figure 1 it is contemplated that any number of UEs, relay UEs, and BSs may be included in the wireless communication system 100.

[0031] Due to the long distance between UE 101 and BS 102, they communicate with each other via relay UE 103. UE 101 can be connected to relay UE 103 via a network interface (e.g., the PC5 interface as specified in 3GPP standard documents). Relay UE 103 can be connected to BS 102 via a network interface (e.g., the Uu interface as specified in 3GPP standard documents). Refer to Figure 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.

[0032] In some embodiments of the present application, UE 101 or relay UE 103 may include a computing device, such as a desktop computer, laptop computer, personal digital assistant (PDA), tablet computer, smart TV (e.g., a TV connected to the Internet), set-top box, game console, security system (including security cameras), in-vehicle computer, network device (e.g., router, switch, and modem), etc.

[0033] In some other embodiments of the present application, UE 101 or relay UE 103 may include a portable wireless communication device, smartphone, cellular phone, flip phone, device with a subscriber identity module, personal computer, selective call receiving circuitry, or any other device capable of transmitting and receiving communication signals over a wireless network.

[0034] In some other embodiments of the present application, UE 101 or relay UE 103 may include a wearable device, such as a smartwatch, fitness bracelet, optical head-mounted display, etc. Additionally, UE 101 or relay UE 103 may be referred to as a subscriber unit, mobile station, mobile terminal, user, terminal, wireless terminal, fixed terminal, subscriber station, user terminal, or device, or described using other terms used in the art.

[0035] BS 102 may be distributed throughout a geographical area. In certain embodiments of the present application, each of BS 102 may also be referred to as an access point, access terminal, base station, base station unit, macrocell, Node B, evolved Node B (eNB), gNB, home Node B, relay node, or device, or described using other terms used in the art. BS 102 is typically part of a radio access network, which may include one or more controllers communicatively coupled to one or more corresponding BS 102.

[0036] The wireless communication system 100 can be compatible with any type of network capable of transmitting and receiving wireless communication signals. For example, the wireless communication system 100 is compatible with wireless communication networks, cellular phone networks, time division multiple access (TDMA)-based networks, code division multiple access (CDMA)-based networks, orthogonal frequency division multiple access (OFDMA)-based networks, LTE networks, 3GPP-based networks, 3GPP 5G networks, satellite communication networks, high altitude platform networks, and / or other communication networks.

[0037] In some embodiments of the present application, the wireless communication system 100 is compatible with 5G NR of the 3GPP protocol, where the BS 102 transmits data using an OFDM modulation scheme on the downlink (DL), and the UE 101 (e.g., UE 101 or other similar UEs) transmits data using a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) or cyclic prefix OFDM (CP-OFDM) scheme on the uplink (UL). However, more generally, the wireless communication system 100 can implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0038] In some embodiments of the present application, the BS 102 can communicate using other communication protocols, such as the IEEE 802.11 series of wireless communication protocols. In addition, in some embodiments of the present application, the BS 102 can communicate on licensed spectrum, while in other embodiments, the BS 102 can communicate on unlicensed spectrum. The present application is not intended to be limited to the implementation of any specific wireless communication system architecture or protocol. In still other embodiments of the present application, the BS 102 can communicate with the UE 101 using the 3GPP 5G protocol.

[0039] The UE 101 can 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, since the UE 101 does not know when the BS 102 will transmit a data packet to it, the UE 101 must always be in a wake-up state to monitor the downlink channel (e.g., the physical downlink control channel (PDCCH)) in order to be ready to receive data packets from the BS 102. However, if the UE 101 always keeps monitoring the downlink channel even when there is no traffic between the BS 102 and the UE 101, it will result in significant power waste, which is a problem for power-constrained UEs or power-sensitive UEs.

[0040] Figure 2 Exemplary flowchart illustrating a sidelink RRC reconfiguration process according to some embodiments of the present application.

[0041] AsFigure 2 As shown in Figure 2 , in step 201, UE (a) (e.g., UE 101 as described and shown in Figure 1 Figure 1 ) initiates a sidelink RRC reconfiguration process to UE (b) (e.g., relay UE 103 as described and shown in Figure 1 Figure 1 ) by transmitting an RRCReconfigurationSidelink message to UE (b).

[0042] If the sidelink RRC reconfiguration process is successfully completed, then in step 202, UE (b) may transmit an "RRC reconfiguration complete sidelink message" to UE (a), e.g., an RRCReconfigurationCompleteSidelink message as specified in the 3GPP standard document. Alternatively, if the sidelink RRC reconfiguration process is not successfully completed, then in step 202, UE (b) may transmit an "RRC reconfiguration failure sidelink message" to UE (a), e.g., an RRCReconfigurationFailureSidelink message as specified in the 3GPP standard document.

[0043] The purpose of the sidelink RRC reconfiguration process is to modify the PC5 RRC connection, e.g., to establish, modify, or release a sidelink data radio bearer (DRB), configure NR sidelink measurements and reporting, and configure sidelink channel state information (CSI) reference signal resources.

[0044] UE (e.g., UE (a) as described and shown in Figure 2 Figure 2 ) may initiate a sidelink RRC reconfiguration process and perform operations on the corresponding PC5 RRC connection under the following circumstances:

[0045] - Release of a sidelink DRB associated with a peer UE (e.g., UE (b) as described and shown in Figure 2 Figure 2 );

[0046] - Establishment of a sidelink DRB associated with a peer UE;

[0047] - Modification of parameters (SLRB-Config) included in the sidelink radio bearer of a sidelink DRB associated with a peer UE;

[0048] - Configuration information of a peer UE for performing NR sidelink measurements and reporting; and

[0049] - Configuration information of sidelink CSI reference signal resources.

[0050] A UE capable of performing NR sidelink communication may initiate a process for sidelink UE information for NR to report to the network or BS that a declared sidelink radio link failure (RLF) (e.g., expiration of timer T400) or sidelink RRC reconfiguration failure has occurred.

[0051] The following table shows the introduction of timer T400 as specified in 3GPP standard documents, including start conditions, stop conditions, actions upon expiration, and possible common names of the timer.

[0052]

[0053] Figure 3 Exemplary flowchart illustrating a sidelink UE information process according to some embodiments of the present application.

[0054] As Figure 3 shown, in step 301, the UE (e.g., UE 101 as illustrated and described in Figure 1 , or UE (a) as illustrated and described in Figure 2 ) transmits a "Sidelink UE Information NR message" to the BS (e.g., BS 102 as illustrated and described in Figure 1 ), such as a SidelinkUEinformationNR message as specified in 3GPP standard documents. Specifically, the SidelinkUEinformationNR message may include sidelink failure information. The sidelink failure information may include a sidelink destination ID and a sidelink failure reason.

[0055] Currently, in a sidelink relay system under 3GPP 5G NR, details on how to design the adaptation layer and handle failures have not been specifically discussed. Embodiments of the present application provide a failure handling process in a sidelink relay system. For example, when an RLF occurs in the link between a relay UE and another UE, or when the relay UE receives an RRCReconfigurationFailureSidelink message from another UE, whether the relay UE reports a failure notification to the UE. More details will be described below with reference to the accompanying drawings.

[0056] Figure 4 Exemplary protocol stack with a sidelink adaptation protocol (SLAP) layer according to some embodiments of the present application.

[0057] Figure 4 's embodiments show UE1 (e.g., UE 101 as illustrated and described in Figure 1 , UE (a) as illustrated and described in Figure 2 , or UE as illustrated and described in Figure 3 ), a relay UE (e.g., asFigure 1 The relay UE 103 described and shown in Figure 2 or the UE (b) as described and shown in Figure 1 and the protocol stacks at each side of the BS (e.g., the BS 102 as described and shown in Figure 3 or the BS as described and shown in

[0058] Specifically, as shown in Figure 4 the UE1 side includes protocol layers of PC5-PHY, PC5-MAC, PC5-RLC, Uu-PDCP, and Uu-SDAP. The relay UE side includes protocol layers of PC5-PHY, PC5-MAC, PC5-RLC, Uu-PHY, Uu-MAC, and Uu-RLC. The BS side includes protocol layers of Uu-PHY, Uu-MAC, Uu-RLC, Uu-PDCP, and Uu-SDAP. According to some embodiments of the present application, the relay UE side and the BS side further include an SLAP layer, as shown in Figure 4 Specific examples of using the SLAP layer are described in the following embodiments, such as Figure 5 and 6 .

[0059] Figure 5 The flowchart illustrates a method for receiving response information according to some embodiments of the present application. The method may be performed by a relay UE (e.g., Figure 1 the relay UE 103 described and shown in Figure 2 or the UE (b) as described and shown in Figure 5 Although described with respect to the UE, it should be understood that other devices may be configured to perform a method similar to

[0060] In the exemplary method 500 shown in Figure 5 in operation 501, the relay UE receives an RRC setup request from the UE (e.g., Figure 1 the UE 101 described and shown in Figure 1 In operation 502, the relay UE transmits an RRC setup request to the BS (e.g., the BS 102 as described and shown in Figure 3 or the BS as described and shown in Figure 5 The embodiments of

[0061] In operation 503, the relay UE receives response information from the BS. The response information includes at least one of a C-RNTI and the ID of the UE. In an example, at least one of the C-RNTI and the ID of the UE is used in the header of the SLAP layer of the relay UE.

[0062] In operation 504, the relay UE transmits the response information to the UE. In an example, the response information includes a mapping association between the C-RNTI and the ID of the UE. The response information may further include configuration information of the SLAP layer of the relay UE. In other examples, the response information includes the ID of the logical channel between the UE and the BS. Specifically, the relay UE or the BS may configure the UEID with a reduced size to be included in the header in the packet data unit (PDU) format. Therefore, the mapping between the C-RNTI and the UE ID with a reduced size should be configured.

[0063] In another example, the response information includes a mapping association between the "ID of the logical channel between the UE and the relay UE" and the "ID of the logical channel between the relay UE and the BS". In other words, in this example, the ID of the logical channel between the first UE and the relay UE is included in the header in the PDU format. After the relay UE receives a packet from the UE in one logical channel ID, the relay UE will deliver this PDU containing this packet to the corresponding ID of the logical channel between the relay UE and the BS based on the mapping association.

[0064] In an additional example, the response information includes a mapping association between the "ID of the logical channel between the UE and the relay UE" and the "ID of the logical channel between the UE and the BS". In other words, in this example, the ID of the logical channel between the first UE and the BS is included in the header in the PDU format. After the relay UE receives a packet from the UE in one logical channel ID, the relay UE will add this ID of the logical channel between the UE and the BS based on the mapping association in the header in the PDU format, and deliver this PDU containing this packet to one of the logical channels between the relay UE and the BS based on the mapping association.

[0065] In an embodiment, the relay UE further receives an RRC setup complete message from the UE and transmits an RRC setup complete message to the BS.

[0066] In other embodiments, the relay UE receives one or more packets associated with different UE bearers from a UE. The relay UE then transmits an SLAP PDU containing the received one or more packets to the BS. The header of the SLAP PDU may include one or more logical channel IDs associated with the one or more packets. The one or more logical channel IDs may be the "ID of the logical channel between the UE and the relay UE" or the "ID of the logical channel between the UE and the BS". That is, multiple packets associated with different UE bearers may be multiplexed into one PDU format. Multiple logical channel IDs should be added in the header.

[0067] The details described in all other embodiments of this application (e.g., details about the response information received from the BS) apply to Figure 5 the embodiments of. In addition, Figure 5 the details described in the embodiments of apply to Figures 1 to 4 all embodiments from to 6 to 10.

[0068] Figure 6 A flowchart illustrating a method for transmitting response information according to some embodiments of this application. The method may be performed by a BS (e.g., the BS 102 illustrated and shown in Figure 1 , or the BS illustrated and shown in Figure 3 . Although described with respect to a BS, it should be understood that other devices may be configured to perform a method similar to Figure 6 's method.

[0069] In the exemplary method 600 shown in Figure 6 , in operation 601, the BS receives an RRC setup request from a relay UE (e.g., the relay UE 103 illustrated and shown in Figure 1 , or the UE (b) illustrated and shown in Figure 2 ). Figure 6 The embodiments of assume that a PC5 RRC connection of the link between a UE (e.g., the UE 101 illustrated and shown in Figure 1 ) and the relay UE has been established, and an RRC connection of the link between the relay UE and the BS has been established. In operation 602, the BS transmits response information to the relay UE. The response information includes at least one of a C-RNTI and the ID of the UE.

[0070] Figure 6 The response information in the embodiments of has a format or content similar to that of the response information in Figure 5 's embodiments. For example, similar to the embodiments of Figure 5 , in Figure 6In an embodiment, the response information may include a mapping association between the C-RNTI and the ID of the UE. The response information may further include the ID of the logical channel between the UE and the BS.

[0071] In an example, the BS receives an RRC setup complete message from the relay UE. For example, the UE transmits an RRC setup complete message to the relay UE, and then the relay UE transmits the RRC setup complete message to the BS.

[0072] In other examples, the BS receives a SLAP PDU from the relay UE. The SLAP PDU includes one or more packets associated with different UE bearers. One or more packets are transmitted from the UE. Figure 6 The SLAP PDU in the embodiment of Figure 5 may have a format or content similar to the format or content of the SLAP PDU in the embodiment of

[0073] The details described in all other embodiments of this application (for example, details about the response information transmitted to the relay UE) apply to Figure 6 the embodiment of Figure 6 The details described in the embodiment of Figures 1 to 5 apply to all embodiments of

[0074] The following text describes a specific embodiment 1 of the method as shown and illustrated in Figure 5 and 6 Specific embodiment 1 of the method shown and illustrated in

[0075] Embodiment 1

[0076] According to Embodiment 1, a UE (for example, UE 101 as shown and illustrated in Figure 1 ), a relay UE (for example Figure 1 the relay UE 103 as illustrated and shown in Figure 1 ) and a BS (for example, BS 102 as illustrated and shown in

[0077] (1) The RRC connection of the PC5 link between UE 101 and the relay UE 103 is established. The RRC connection of the Uu link between the relay UE and BS 102 is established.

[0078] (2) UE 101 transmits an RRC setup request to the relay UE 103.

[0079] (3) The relay UE 103 forwards the RRC setup request to the BS 102.

[0080] ·The RRC setup request may be included in another RRC message, such as the RRCReconfigurationSidelink message. That is, the relay UE 103 may transmit an RRCReconfigurationSidelink message containing the RRC setup request to the BS 102.

[0081] (4) The BS 102 transmits an RRC reconfiguration message containing the response to the relay UE 103. The response is relayed by the relay UE 103 and transmitted to the UE 101.

[0082] ·The RRC reconfiguration message relayed by the relay UE 103 may contain the C-RNTI of the UE 101. The RRC reconfiguration message may further contain the mapping association between the C-RNTI and the ID of the UE 101. At least one of the C-RNTI and the ID of the UE 101 is to be included in the header of the SLAP layer of the relay UE 103.

[0083] (5) The relay UE 103 transmits the response to the UE 101.

[0084] ·After receiving the RRC setup request, the BS 102 may transmit an RRC setup message to the UE 101 via the relay UE 103. The RRC setup message may be included in the response transmitted by the relay UE 103.

[0085] (6) The UE 101 transmits an RRC setup completion message to the BS 102 via the relay UE 103.

[0086] ·The ID of the UE 101 (e.g., C-RNTI) should be added to the RRC setup completion message.

[0087] (7) The UE 101 will transmit data packets associated with different logical channel IDs to the relay UE 103.

[0088] (8) After the relay UE 103 receives multiple data packets associated with different logical channel IDs, the relay UE 103 may transmit a PDU format to the BS 102.

[0089] ·Multiple data packets associated with different UE bearers may be multiplexed into one PDU format.

[0090] ·Multiple logical channel IDs should be added to the header of the PDU format.

[0091] (9) The BS 102 receives the PDU format containing multiple data packets associated with different UE bearers.

[0092] · BS 102 can distinguish different UE bearers based on the logical channel ID in the header of the PDU format.

[0093] Figure 7 A flowchart illustrating a method for transmitting failure information according to some embodiments of the present application. The method may be performed by a relay UE (e.g., Figure 1 the relay UE 103 as illustrated and shown in Figure 2 or the UE (b) as illustrated and shown in Figure 7 . Although described with respect to a UE, it should be understood that other devices may be configured to perform a method similar to

[0094] In the exemplary method 700 as shown in Figure 7 , in operation 701, a relay UE (e.g., Figure 1 the relay UE 103 as illustrated and shown in Figure 1 ) establishes a PC5 RRC connection for the link between the UE (e.g.,

[0095] In operation 702, the relay UE establishes an RRC connection for the link between the relay UE and the BS (e.g., BS102 as illustrated and shown in Figure 1 or the BS as illustrated and shown in Figure 3 ). In operation 703, the relay UE establishes a relay connection for the link between the UE and the BS.

[0096] In operation 704, the relay UE detects whether a failure occurs on the link between the UE and the relay UE. In operation 705, if the relay UE detects a failure on the link between the UE and the relay UE, then the relay UE transmits failure information to the BS. For example, the failure information may be included in one of the following:

[0097] · A sidelink UE information message, e.g., a SidelinkUEinformation message as specified in the 3GPP standard document;

[0098] · A control PDU in the SLAP layer of the relay UE; and

[0099] · A media access control (MAC) control element (CE).

[0100] In some embodiments, the failure information includes a UE ID configured by the BS. The UE ID may be a C-RNTI or the ID of the UE. The UE ID may be used in the header of the SLAP layer of the relay UE.

[0101] In some other embodiments, the failure information includes at least one of the following: cause of failure; ID of the UE; and ID of the relay UE. The cause of failure may be a Listen-Before-Talk (LBT) failure or a beam failure recovery failure.

[0102] In some embodiments, based on at least one of the following conditions, the relay UE detects a failure occurring on the link between the UE and the relay UE:

[0103] · The maximum number of retransmissions of the radio link control (RLC) entity of the relay UE is reached;

[0104] · The timer for the transmission of the RRC reconfiguration for the sidelink expires;

[0105] · The maximum number of consecutive Hybrid Automatic Repeat reQuest (HARQ) Discontinuous Transmission (DTX) is reached;

[0106] · Integrity check fails;

[0107] · LBT fails; and

[0108] · Beam failure recovery fails.

[0109] In some embodiments, the relay UE transmits an RRC reconfiguration sidelink message to the UE. In some cases, the relay UE further receives an RRC reconfiguration failure sidelink message from the UE. When receiving the RRC reconfiguration failure sidelink message, the relay UE detects a failure occurring on the link between the UE and the relay UE.

[0110] Details described in all other embodiments of the present application (e.g., details of how to handle a failure on the link between the UE and the relay UE) apply to Figure 7 the embodiments. In addition, Figure 7 details described in the embodiments of Figures 1 to 6 apply to all embodiments of

[0111] The following text describes specific Embodiment 2 of the method as shown and illustrated in Figure 7 .

[0112] Embodiment 2

[0113] According to Embodiment 2, a UE (e.g., UE 101 as shown and illustrated in Figure 1 ), a relay UE (e.g., relay UE 103 as illustrated and shown in Figure 1 ), and a BS (e.g., BS 102 as illustrated and shown in Figure 1 ) perform the following steps:

[0114] (1) The RRC connection of the PC5 link between the UE 101 and the relay UE 103 has been established. The RRC connection of the Uu link between the relay UE and the BS 102 has been established.

[0115] (2) Establish the relay RRC connection of the link between the UE 101 and the BS 102. The RRC relay connection of the link is a logical link and can also be referred to as the "end-to-end link" between the UE 101 and the BS 102.

[0116] (3) The following possible steps of the relay UE 103 may exist:

[0117] · Step (3a): When at least one of the following conditions occurs, the relay UE 103 detects the sidelink RLF between the UE 101 and the relay UE 103:

[0118] When the sidelink RLC entity of the relay UE 103 indicates that the maximum number of retransmissions for a specific destination (i.e., the UE 101)

[0119] has been reached; or

[0120] When the timer T400 expires; or

[0121] When the sidelink MAC entity of the relay UE 103 indicates that the maximum number of consecutive HARQ DTX for a specific destination has been reached; or

[0122] When the integrity check failure indication of the SL-SRB2 (sidelink signaling radio bearer 2) or SL-SRB3 from the sidelink PDCP entity of the relay UE 103 occurs:

[0123] a) LBT failure; or

[0124] b) Beam failure recovery failure.

[0125] · Step (3b): After the relay UE 103 transmits the RRCReconfigurationSidelink message to the UE 101, the relay UE 103 receives the RRCRecononfigurationFailureSidelink message from the UE 101.

[0126] (4) The relay UE 103 reports the failure information to the BS 102. According to the following different cases 1-1 to 1-4, the failure information can be different.

[0127] · Case 1-1: A sidelink Radio Link Failure (RLF) occurs between UE 101 and relay UE 103. The relay UE will declare the sidelink RLF.

[0128] · Case 1-2: The relay UE 103 receives an RRCReconfigurationFailureSidelink message from UE 101.

[0129] - For Case 1-1 and Case 1-2:

[0130] The relay UE 103 reports failure information including the UE ID configured for BS 102. The UE ID configured by BS 102 can be the C-RNTI or UE ID used in the SLAP layer of the relay UE 103.

[0131] The SidelinkUEinformation message or control PDU in the SLAP layer can be used to transmit the failure information.

[0132] · Case 1-3: Unlicensed spectrum is used for the PC5 link between UE 101 and relay UE 103. It may be necessary to indicate the LBT failure to BS 102.

[0133] - For Case 1-3:

[0134] A new cause (e.g., LBT failure) should be added in the SidelinkUEinformation message; and

[0135] The corresponding UE ID is also required. For example, at least one of the IDs of UE 101 and relay UE 103 is included in the SidelinkUEinformation message.

[0136] Case 1-4: FR2 is used for the link between UE 101 and relay UE 103. Beam failure related information can be indicated to BS 102.

[0137] - For Case 1-4:

[0138] In FR2, BS 102 or the relay UE 103 will configure a set of available beams. Once all beams fail, the relay UE 103 reports beam failure recovery failure and the corresponding UE ID (e.g., at least one of the IDs of UE 101 and relay UE 103) to the serving cell of BS 102.

[0139] Figure 8Flowchart showing a method for transmitting a failure notification according to some embodiments of the present application. The method may be performed by a relay UE (e.g., Figure 1 the relay UE 103 as illustrated and shown in Figure 2 or a UE (b) as illustrated and shown in Figure 8 ). Although described with respect to a UE, it should be understood that other devices may be configured to perform a method similar to

[0140] In the exemplary method 800 as shown in Figure 8 at operation 801, a relay UE (e.g., Figure 1 the relay UE 103 as illustrated and shown in Figure 1 establishes a relay logical connection for a link between a UE (e.g., Figure 1 the UE 101 as illustrated and shown in Figure 3 and a BS (e.g., the BS 102 as illustrated and shown in

[0141] At operation 802, the relay UE detects whether a failure has occurred on the link between the relay UE and the BS. Figure 8 Embodiments of

[0142] assume that a PC5 RRC connection for the link between the UE and the relay UE has been established, and an RRC connection for the link between the relay UE and the BS has been established.

[0143] In an embodiment, if the relay UE completes a successful RRC reestablishment process, the relay UE transmits a successful recovery notification.

[0144] In other embodiments, if the relay UE detects an RRC reestablishment failure on the link between the relay UE and the BS, the relay UE transmits a recovery failure notification.

[0145] In an example, the failure notification, the successful recovery notification, or the recovery failure notification may be included in one of the following:

[0146] · RRC signaling;

[0147] · Control PDU in the SLAP layer; and

[0148] · MAC CE.

[0149] Details described in all other embodiments of this application (e.g., details on how to handle failures on the link between the UE and the relay UE) apply to Figure 8 the embodiments. In addition, details described in the embodiments of Figure 8 apply to all embodiments of Figures 1 to 7 , 9, and 10.

[0150] Figure 9 A flowchart illustrating a method for initiating a relay reselection process according to some embodiments of this application. The method may be performed by a UE (e.g., UE 101 as illustrated and shown in Figure 1 , UE (a) as illustrated and shown in Figure 2 , or UE as illustrated and shown in Figure 3 ). Although described with respect to a UE, it should be understood that other devices may be configured to perform a method similar to the method of Figure 9 .

[0151] Figure 9 The embodiments of Figure 1 assume that a PC5 RRC connection for the link between a UE (e.g., UE 101 as illustrated and shown in Figure 1 ) and a relay UE (e.g., relay UE 103 as illustrated and shown in Figure 2 or UE (b) as illustrated and shown in Figure 1 ), an RRC connection for the link between the relay UE and a BS (e.g., BS 102 as illustrated and shown in Figure 3 or BS as illustrated and shown in ), and an RRC relay connection for the link between the UE and the BS have been established.

[0152] Figure 9 In an exemplary method 900 as shown in

[0153] , in operation 901, the UE receives a failure-associated notification from the relay UE. The failure-associated notification indicates a failure on the link between the relay UE and the BS. In an embodiment, the access stratum (AS) layer of the UE transmits the failure-associated notification to the non-access stratum (NAS) layer of the UE.

[0154] In operation 902, the UE initiates a relay reselection process. The relay reselection process may be initiated in response to a notification associated with a failure indicating a radio link failure (RLF) on the link between the relay UE and the BS. In an instance, when initiating the relay reselection process, the UE monitors a discovery resource pool.

[0155] In other embodiments, the UE receives a recovery failure notification from a relay UE. When receiving a recovery failure notification from the relay UE, a relay reselection process is initiated. For example, during the initiation of the relay reselection process, the UE monitors a discovery resource pool in response to receiving a recovery failure notification from the relay UE. Then, the UE may further select a second relay UE and establish a PC5 RRC connection for the link between the UE and the second relay UE.

[0156] In an example, each of the notification associated with failure, successful recovery notification, and recovery failure notification may be included in RRC signaling, a control PDU in the SLAP layer, or a MAC CE.

[0157] The details described in all other embodiments of this application (e.g., details on how to handle failures on the link between the UE and the relay UE) apply to Figure 9 the embodiments of. Additionally, the details described in Figure 9 the embodiments of apply to Figures 1 to 8 all embodiments of and 10.

[0158] The following text describes specific embodiment 3 of the method as shown and illustrated in Figure 8 and 9 .

[0159] Embodiment 3

[0160] According to Embodiment 3, a UE (e.g., UE 101 as shown and illustrated in Figure 1 ), a relay UE (e.g., relay UE 103 as illustrated and shown in Figure 1 ), and a BS (e.g., BS 102 as illustrated and shown in Figure 1 ) perform the following steps:

[0161] (1) An RRC connection for the PC5 link between UE 101 and relay UE 103 is established. An RRC connection for the Uu link between the relay UE and BS 102 is established.

[0162] (2) A relay RRC connection for the link between UE 101 and BS 102 is established. The RRC relay connection for the link is a logical link and may also be referred to as the "end - to - end link" between UE 101 and BS 102.

[0163] (3) When the following conditions are met, the relay UE 103 transmits an RLF notification to UE 101:

[0164] · Case 2 - 1: An RLF occurs between the relay UE 103 and BS 102;

[0165] When the UE 101 receives an RLF notification from the relay UE 103:

[0166] · The UE 101 is triggered to monitor the discovery resource pool; and

[0167] · The AS layer of the UE 101 delivers the information of the RLF to the NAS layer of the UE 101.

[0168] (5) When the relay UE 103 completes the recovery process, it transmits a successful recovery notification.

[0169] · After receiving the successful recovery notification, the UE 101 stops the relay reselection process; or

[0170] · After receiving the successful recovery notification, the UE 101 stops monitoring the discovery resource pool.

[0171] (6) When the recovery in the recovery process fails, the relay UE 103 transmits a recovery failure notification to the UE 101.

[0172] · When the UE 101 receives the recovery failure notification, the UE 101 is triggered to initiate the relay reselection process.

[0173] Figure 10 A simplified block diagram of a device for a failure handling process according to some embodiments of the present application is illustrated.

[0174] In some embodiments of the present application, the device 1000 may be a UE (e.g., the UE 101 as illustrated and shown in Figure 1 ), the UE (a) as illustrated and shown in Figure 2 ), or the UE as illustrated and shown in Figure 3 ), which may at least execute the method described in Figure 9 .

[0175] In some other embodiments of the present application, the device 1000 may be a relay UE (e.g., the relay UE 103 as illustrated and shown in Figure 1 or the UE (b) as illustrated and shown in Figure 2 ), which may at least execute the method described in Figure 5 Figure 7 or Figure 8 .

[0176] In some additional embodiments of the present application, the device 1000 may be a BS (e.g., the BS 102 as illustrated and shown in Figure 1 or the BS as illustrated and shown in Figure 3 ), which may at least execute the method described in Figure 6 .

[0177] As Figure 10 shown in, device 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, the at least one processor 1008 being 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.

[0178] Although in Figure 10 the 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, plural may be contemplated unless explicitly stated to be limited to the singular. 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 certain embodiments of the present application, device 1000 may further include an input device, a memory, and / or other components.

[0179] In some embodiments of the present application, the at least one non-transitory computer-readable medium 1006 may have computer-executable instructions stored thereon, the computer-executable instructions being programmed to perform operations of a method such as any of those described in view of Figures 5 to 9 any of the above.

[0180] Those of ordinary skill in the art will understand that the steps of the methods described in connection with the aspects disclosed herein may be embodied directly in hardware, in software modules executed by a processor, or in a combination of both. The software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. Additionally, in some aspects, the operations of the methods may reside as one or any combination or collection of code and / or instructions on a non-transitory computer-readable medium that can be incorporated into a computer program product.

[0181] While the present disclosure has been described in terms of its specific embodiments, it will be apparent that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added, or replaced in other embodiments. Additionally, all elements of each figure are not necessary for the operation of the disclosed embodiments. For example, it will enable those of ordinary skill in the art to make and use the teachings of the present disclosure by simply employing the elements of the independent claims. Accordingly, the embodiments of the present disclosure as described herein are intended to be illustrative and not restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0182] In this document, the term "includes", "including", or any other variant thereof is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "a", "an", or the like does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element. Further, the term "another" is defined as at least a second or more. As used herein, the terms "has", "have", and the like are defined as "includes".

Claims

1. A device for wireless communication, comprising: At least one non-transitory computer-readable medium having computer-executable instructions stored thereon; At least one receiving circuit system; At least one transmitting circuit system; And At least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuit system, and the at least one transmitting circuit system, Wherein the computer-executable instructions cause the at least one processor to: Establish a relay logical connection for a link between a user equipment UE and a base station BS; Detect whether a radio link failure RLF occurs on a link between a relay UE and the BS, wherein a PC5 radio resource control RRC connection for a link between the UE and the relay UE has been established, and wherein an RRC connection for a link between the relay UE and the BS has been established; And In response to detecting that the RLF occurs on the link between the relay UE and the BS, generate an RLF notification and transmit the RLF notification to the UE.

2. The device according to claim 1, wherein the RLF notification is included in one of the following: RRC signaling; A control packet data unit PDU in a sidelink adaptation protocol SLAP layer; or A media access control MAC control element CE.

3. The device according to claim 1, wherein the computer-executable instructions cause the at least one processor to: In response to completing a successful RRC reconstruction process, transmit a successful recovery notification.

4. The device according to claim 3, wherein the successful recovery notification is included in one of the following: RRC signaling; A control packet data unit PDU in a sidelink adaptation protocol SLAP layer; or A media access control MAC control element CE.

5. The device according to claim 1, wherein the computer-executable instructions cause the at least one processor to: In response to detecting an RRC reconstruction failure on the link between the relay UE and the BS, transmit a recovery failure notification.

6. The device according to claim 5, wherein the recovery failure notification is included in one of the following: RRC signaling; A control packet data unit PDU in a sidelink adaptation protocol SLAP layer; or A media access control MAC control element CE.

7. A device for wireless communication, comprising: At least one non-transitory computer-readable medium having computer-executable instructions stored thereon; At least one receiving circuit system; At least one transmitting circuit system; And At least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuit system, and the at least one transmitting circuit system, Wherein the computer-executable instructions cause the at least one processor to: Receiving a radio link failure (RLF) notification from a relay user equipment (UE), wherein a PC5 radio resource control (RRC) connection of a link between the UE and the relay UE has been established, wherein an RRC connection of a link between the relay UE and a base station (BS) has been established, and wherein an RRC relay connection of a link between the UE and the BS has been established; and In response to the RLF notification indicating detection of an RLF on the link between the relay UE and the BS, initiating a relay reselection process.

8. The apparatus according to claim 7, wherein the RLF notification is included in one of the following: RRC signaling; A control packet data unit (PDU) in a side link adaptation protocol (SLAP) layer; or A media access control (MAC) control element (CE).

9. The apparatus according to claim 7, wherein the computer-executable instructions cause the at least one processor to: Receive a successful recovery notification from the relay UE.

10. The apparatus according to claim 9, wherein the successful recovery notification is included in one of the following: RRC signaling; A control packet data unit (PDU) in a side link adaptation protocol (SLAP) layer; or A media access control (MAC) control element (CE).

11. The apparatus according to claim 9, wherein the computer-executable instructions cause the at least one processor to perform one of the following: Stop the relay reselection process; or Stop monitoring the discovery resource pool.

12. The apparatus according to claim 7, wherein the computer-executable instructions cause the at least one processor to: Receive a recovery failure notification from the relay UE.

13. The apparatus according to claim 12, wherein the at least one processor initiates the relay reselection process in response to receiving the recovery failure notification from the relay UE.

14. The apparatus according to claim 7, wherein to initiate the relay reselection process, the at least one processor: Monitors the discovery resource pool in response to receiving a recovery failure notification from the relay UE.

15. The apparatus according to any one of claims 12-14, wherein the recovery failure notification is included in one of the following: RRC signaling; A control packet data unit (PDU) in a side link adaptation protocol (SLAP) layer; or A media access control (MAC) control element (CE).

16. The apparatus according to claim 7, wherein to initiate the relay reselection process, the at least one processor: Select a second relay UE; and Establish a PC5 RRC connection of a link between the UE and the second relay UE.

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