Method and apparatus for wireless communication

Abstract

Embodiments of the present disclosure relate to methods and apparatus for wireless communications. According to some embodiments of the present disclosure, a method may include: at a first user equipment (UE), transmitting a radio resource control (RRC) reconfiguration sidelink via a relay message on a sidelink between the first UE and a second UE; and starting a timer associated with the RRC reconfiguration sidelink via a relay message. The second UE may act as a relay node and may transmit the received message to a destination UE or base station. The destination UE or base station may respond to the first UE before the timer expires.

Description

Technical Field

[0001] Embodiments of the present application generally relate to wireless communication technology, and more particularly to coverage extension based on sidelink communication in a wireless communication system. Background Art

[0002] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. Wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of wireless communication systems may include fourth generation (4G) systems such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems, which may also be referred to as new radio (NR) systems.

[0003] In the above wireless communication system, a user equipment (UE) can communicate with another UE via a data path supported by an operator network (eg, a cellular or Wi-Fi network infrastructure). The data path supported by the operator network may include a base station (BS) and multiple gateways.

[0004] Some wireless communication systems may support sidelink (SL) communications, where devices (e.g., UEs) that are relatively close to each other may communicate directly with each other via the SL, rather than being linked through a BS. The term "SL" may refer to a direct radio link established for communication among devices, rather than communicating via a cellular infrastructure (uplink and downlink) as discussed above. The term "SL" may also be referred to as a sidelink communication link.

[0005] Currently, the proximity reachability based on the sidelink communication is limited to a single hop. The relay function based on the sidelink is not supported. The industry expects a technology for supporting the relay function based on the sidelink. Summary of the invention

[0006] According to some embodiments of the present application, a method may include: at a first user equipment (UE), transmitting a radio resource control (RRC) reconfiguration sidelink via a relay message on a sidelink between the first UE and a second UE; and starting a timer associated with the RRC reconfiguration sidelink via the relay message.

[0007] According to some other embodiments of the present application, a method may include receiving, at a second user equipment (UE), a radio resource control (RRC) reconfiguration sidelink via a relay message on a sidelink between a first UE and the second UE, wherein the destination of the RRC reconfiguration sidelink via the relay message is a third UE.

[0008] According to some other embodiments of the present application, a method may include, at a third user equipment (UE), receiving a radio resource control (RRC) reconfiguration sidelink via a relay message on a sidelink between the third UE and a second UE, wherein the destination of the RRC reconfiguration sidelink via the relay message is the third UE.

[0009] According to some other embodiments of the present application, a method may include, at a first user equipment (UE), transmitting a radio resource control (RRC) setup request message on a sidelink, wherein the RRC setup request message includes an identification of the first UE.

[0010] According to some other embodiments of the present application, a method may include, at a second user equipment (UE), receiving a first radio resource control (RRC) setup request message on a sidelink, wherein the first RRC setup request message includes an identification of a first UE.

[0011] According to some other embodiments of the present application, a method may include receiving, at a base station (BS), from a second user equipment (UE), a radio resource control (RRC) setup request message including an identification of a first UE.

[0012] Some embodiments of the present application also provide an apparatus comprising: at least one non-transitory computer-readable medium having computer-executable instructions stored therein; 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. The computer-executable instructions are programmed to implement any method as stated above with the at least one receiving circuit system, the at least one transmitting circuit system, and the at least one processor.

[0013] The embodiments of the present application provide a technical solution for supporting a sidelink-based relay function and can facilitate and improve the implementation of 5G NR technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to describe the manner in which the advantages and features of the present application can be obtained, the description of the present application is presented by reference to specific embodiments of the present application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and therefore should not be considered to limit its scope.

[0015] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application;

[0016] Figure 2An exemplary flow chart illustrating a sidelink RRC reconfiguration procedure according to some embodiments of the present application;

[0017] Figure 3 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application;

[0018] Figure 4 Describes an exemplary procedure for establishing a connection via a UE-to-UE relay according to some embodiments of the present application;

[0019] Figure 5 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application;

[0020] Figure 6 An exemplary procedure for establishing a connection via a UE to a network relay according to some embodiments of the present application is described; and

[0021] Figure 7 A block diagram illustrating an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0022] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present disclosure, and is not intended to represent the only form in which the present disclosure can be practiced. It should be understood that the same or equivalent functions can be achieved by different embodiments that are intended to be included in the spirit and scope of the present disclosure.

[0023] Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architectures and new service scenarios (e.g., 3rd Generation Partnership Project (3GPP) 5G (NR), 3GPP Long Term Evolution (LTE) Release 8, etc.). It is contemplated that, with the development of network architectures and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical issues; and in addition, the terms listed in the present disclosure may be changed, which should not affect the principles of the present disclosure.

[0024] Figure 1 A schematic diagram illustrating a wireless communication system 100 according to some embodiments of the present disclosure.

[0025] As in Figure 1As shown in , the wireless communication system 100 may support sidelink communication. In the context of the present application, sidelink communication may be classified according to the wireless communication technology employed. For example, NR sidelink communication (specified in 3GPP specification TS 38.311) may refer to access layer (AS) functionality that uses NR technology to implement at least vehicle-to-everything (V2X) communication between neighboring UEs as defined in 3GPP specification TS 23.287 but does not traverse any network nodes. V2X sidelink communication (specified in 3GPP specification TS 36.311) may refer to AS functionality that uses Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) (E-UTRA) technology to implement V2X communication between neighboring UEs as defined in 3GPP specification TS 23.285 but does not traverse any network nodes. However, if not specified, "sidelink communication" may refer to NR sidelink communication, V2X sidelink communication, or any sidelink communication employing other wireless communication technologies.

[0026] refer to Figure 1 , the wireless communication system 100 may include some base stations (eg, BS 102 and BS 103) and some UEs (eg, UE 101A, UE 101B, and UE 101C). Figure 1 A specific number of UEs and BSs are depicted in FIG. 1 , but it is contemplated that any number of UEs and BSs may be included in the wireless communication system 100 .

[0027] UE and BS may support communications based on, for example, 3G, Long Term Evolution (LTE), Advanced LTE (LTE-A), New Radio (NR), or other suitable protocols. In some embodiments of the present disclosure, BS may be referred to as an access point, access terminal, base station, base unit, macro cell, Node B, evolved Node B (eNB), gNB, ng-eNB, home Node B, relay node or device, or described using other terms used in the art. UE may include, for example, but not limited to, computing devices, wearable devices, mobile devices, IoT devices, vehicles, etc. Those skilled in the art should understand that with the development and advancement of technology, the terms described in the present disclosure may change, but should not affect or limit the principles and spirit of the present disclosure.

[0028] UE 101A and UE 101B may be within the coverage area. Figure 1 , UE 101A may be within the coverage of BS 102, and UE 101B may be within the coverage of BS 103. UE 101C may be out of coverage. Figure 1, UE 101C may be outside the coverage of any BS, such as BS 102 and BS 103. UE 101A and UE 101B may be connected to BS 102 and BS 103, respectively, via a network interface, such as a Uu interface specified in a 3GPP standard document. The control plane protocol stack in the Uu interface may include a radio resource control (RRC) layer, which may be referred to as Uu-RRC. BS 102 and BS 103 may be connected to each other via a network interface, such as an Xn interface specified in a 3GPP standard document. UE 101A, UE 101B, and UE 101C may be connected to each other via a PC5 interface, such as specified in a 3GPP standard document, respectively. The control plane protocol stack in the PC5 interface may include a radio resource control (RRC) layer, which may be referred to as PC5-RRC.

[0029] Support for V2X services via the PC5 interface may be provided, for example, by NR sidelink communication or V2X sidelink communication. NR sidelink communication may support one of the following three types of transmission modes for a pair of source layer 2 identifiers and destination layer 2 identifiers: unicast transmission, multicast transmission, and broadcast transmission. When the UE is within coverage or outside coverage, sidelink communication transmission and reception via the PC5 interface are supported. For example, UE101A within the coverage of BS 102 may perform sidelink transmission and reception (e.g., sidelink unicast transmission, sidelink multicast transmission, or sidelink broadcast transmission) via the PC5 interface. UE 101C outside the coverage of both BS 102 and BS 103 may also perform sidelink transmission and reception via the PC5 interface.

[0030] A UE supporting sidelink communication or V2X communication may be referred to as a V2X UE. According to some other embodiments of the present application, the V2X UE may be a mobile phone, a vehicle, a road map device, a computer, a laptop, an IoT (Internet of Things) device, or other types of devices.

[0031] The V2X UE may operate in different modes. At least two sidelink resource allocation modes are defined for sidelink communications. For example, mode 1 may refer to a case where the base station schedules the sidelink resources to be used by the UE for sidelink transmission, and mode 2 may refer to a case where the UE determines the sidelink transmission resources and timing within a resource pool. The resource pool may be configured by the base station or the network, or may be preconfigured according to a standard. In mode 2, the base station may not need to dynamically schedule the sidelink resources for the UE, and the UE may determine the sidelink transmission resources and timing within the resource pool based on, for example, measurement results and sensing results.

[0032] In Mode 1, the UE may need to be in the RRC_CONNECTED state in order to transmit data. The base station may dynamically schedule resources to the UE for NR sidelink communications via the Physical Downlink Control Channel (PDCCH). In addition, the base station may allocate sidelink resources to the UE using two types of configured sidelink grants (e.g., sidelink resources):

[0033] - Sidelink Configured Grant Type 1 (or Type 1): RRC directly provides only configured sidelink grants for NR sidelink communications; and

[0034] - Sidelink configured grant type 2 (or Type 2): RRC defines the periodicity of the configured sidelink grant, while PDCCH can signal and activate or deactivate the configured sidelink grant.

[0035] For a UE performing NR sidelink communication, more than one configured sidelink grant may be active at a time on a carrier configured for sidelink transmission.

[0036] In mode 2, the UE can transmit data when the UE is in coverage or out of coverage. The UE can autonomously select a sidelink grant from a resource pool provided by system information (e.g., system information block (SIB)) or dedicated signaling when the UE is in coverage of the BS, or autonomously select a sidelink grant from a pre-configured resource pool when the UE is out of coverage of any BS.

[0037] For NR sidelink communications, a resource pool may be provided for a given validity area, wherein the UE does not need to acquire a new resource pool when moving within the validity area, at least when this pool is provided by the SIB (e.g., reusing the validity area of ​​the NR SIB). The UE may be allowed to temporarily use a UE autonomous resource selection method with random selection for sidelink transmissions based on the configuration of an exceptional transmission resource pool as specified in 3GPP specification TS 38.331.

[0038] In some embodiments of the present application, the wireless communication system 100 may support multi-radio dual connectivity (MR-DC) operation. For example, the UE 101A may be connected to the BS 102 serving as a master node (MN) and another BS (not in the UE 101A) serving as a secondary node (SN). Figure 1 ). A MN (e.g., BS 102) and a SN (e.g., another BS) may be connected to each other via a network interface (e.g., an Xn interface). A MN (e.g., BS 102) may be connected to a SN via a network interface (not shown in FIG. Figure 1101A is connected to the core network. In some embodiments of the present application, the SN (e.g., another BS) may also be connected to the core network. The UE 101A may be configured to utilize resources provided by the MN (e.g., BS 102) and the SN (e.g., another BS) to perform data transmission, signaling transmission, or both.

[0039] MN (e.g., BS 102) may refer to a radio access node that provides a control plane connection to a core network. In some embodiments of the present application, in an E-UTRA-NR DC (EN-DC) scenario, MN (e.g., BS 102) may be an eNB. In some other embodiments of the present application, in a next generation E-UTRA-NR DC (NGEN-DC) scenario, MN (e.g., BS 102) may be an ng-eNB. In other embodiments of the present application, in an NR-DC scenario or an NR-E-UTRA DC (NE-DC) scenario, MN (e.g., BS 102) may be a gNB.

[0040] A MN may be associated with a Master Cell Group (MCG). An MCG may refer to a set of serving cells associated with a MN and may include a primary cell (PCell) and optionally one or more secondary cells (SCells). A PCell may provide a control plane connection to a UE (eg, UE 101A).

[0041] SN (e.g., another BS) may refer to a radio access node that does not have a control plane connection to the core network but provides additional resources to UE 101A. In some embodiments of the present application, in an EN-DC scenario, SN may be an en-gNB. In some other embodiments of the present application, in a NE-DC scenario, SN may be an ng-eNB. In other embodiments of the present application, in an NR-DC scenario or a NGEN-DC scenario, SN may be a gNB.

[0042] A SN may be associated with a secondary cell group (SCG). An SCG may refer to a group of serving cells associated with a SN, and may include a primary secondary cell (PSCell) and optionally one or more secondary cells (SCells).

[0043] In some embodiments of the present application, UE 101A may be configured to monitor the MCG of the MN and may detect MCG failures. In some embodiments of the present disclosure, UE 101A may initiate an MCG recovery procedure (e.g., a fast MCG link recovery procedure) to notify the MN of the RLF on the MCG via an SCG link (e.g., SN), so that UE 101A in the RRC_CONNECTED state may initiate a fast MCG link recovery procedure to quickly continue the RRC connection without performing a re-establishment procedure. In some embodiments of the present application, UE 101A may be configured with a separate signaling radio bearer 3 (SRB3) to report MCG failure information when RLF occurs on the MCG.

[0044] Figure 2 An exemplary flow chart illustrating a sidelink RRC reconfiguration procedure 200 according to some embodiments of the present application.

[0045] The purpose of the Sidelink RRC Reconfiguration procedure is to modify the PC5-RRC connection. In some instances, the UE may perform this procedure to establish, modify, or release a sidelink data radio bearer (DRB). In some instances, the UE may perform this procedure to configure NR sidelink measurements and reporting. In some instances, the UE may perform this procedure to configure sidelink channel state information (CSI) reference signal resources.

[0046] refer to Figure 2 In step 211, UE 201A may initiate a sidelink RRC reconfiguration procedure and may transmit an RRC reconfiguration sidelink message to a peer UE (e.g., UE 201B). The peer UE of UE 201A refers to a UE that is or will be performing sidelink communication with UE 201A. For example, in one of the following situations, UE 201A may initiate a sidelink RRC reconfiguration procedure:

[0047] - Release the sidelink DRB associated with the peer UE;

[0048] - Establishing a sidelink DRB associated with a peer UE;

[0049] - modifying parameters in a sidelink radio bearer (SLRB) configuration of a sidelink DRB associated with a peer UE (e.g., SLRB-Config specified in a 3GPP standard document);

[0050] - Configuration of peer UEs to perform NR sidelink measurements and reporting; and

[0051] -Configuration of sidelink CSI reference signal resources.

[0052] After receiving the RRC reconfiguration sidelink message, UE 201B may perform a corresponding operation, for example, releasing or establishing a sidelink DRB between UE 201A and UE 201B. In the case that UE 201B has successfully performed the operation, UE 201B may transmit an RRC reconfiguration complete sidelink message to UE 201A in step 213. Otherwise, in the case that UE 201B fails to perform the operation, UE 201B may transmit an RRC reconfiguration failure sidelink message to UE 201A in step 213.

[0053] In some embodiments of the present disclosure, in response to transmitting an RRC reconfiguration side link message, UE 201A may start a timer (e.g., timer T400 specified in a 3GPP standard document) to control the side link RRC reconfiguration procedure. UE 201A may stop the timer in response to receiving a response to the RRC reconfiguration side link message from UE 201B. In response to the expiration of the timer or the reception of an RRC reconfiguration failure side link message, UE 201A may assume that a failure has occurred on the radio link.

[0054] Currently, the proximity reachability based on sidelink communication is limited to a single hop via, for example, an E-UTRA-based sidelink technology or an NR-based sidelink technology. The relay function based on the sidelink is not supported. For example, reachability to the BS is necessary for the UE to reach a server in a packet data network (PDN). In a communication system using, for example, 5G NR technology, although an out-of-coverage UE can establish a side link with an in-coverage UE, the out-of-coverage UE cannot access the serving BS of the in-coverage UE via the in-coverage UE, and therefore cannot reach the serving BS of the in-coverage UE.

[0055] In addition, the UE (second UE) may establish a side link with two or more UEs (eg, first and third UEs), but the first UE and the third UE may not be able to communicate with each other via the second UE.

[0056] Therefore, the coverage of a single-hop sidelink may be limited.Embodiments of the present application provide a solution for extending the coverage of sidelink communications.

[0057] In some embodiments of the present application, UE-to-network relay is supported. For example, a UE in coverage that communicates with an out-of-coverage UE can be used as a relay UE between a serving BS of the UE in coverage and the out-of-coverage UE. In some embodiments of the present application, UE-to-UE relay is supported. For example, a UE that communicates with two or more UEs (e.g., a first and a third UE) can be used as a relay UE, so that the first UE can communicate with the third UE via the relay UE. More details about the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0058] Figure 3 A schematic diagram illustrating a wireless communication system 300 according to some embodiments of the present application.

[0059] like Figure 3 As shown in FIG. 3 , the wireless communication system 300 may include some UEs (eg, UE 301A, UE 301B, and UE 301C). The wireless communication system 300 may also include some base stations (not shown). Figure 3 ). Figure 3 A particular number of UEs are depicted in FIG. 3 , but it is contemplated that any number of UEs may be included in the wireless communication system 300 .

[0060] refer to Figure 3 , each of UE 301A, UE 301B, and UE 301C may be within coverage or out of coverage. In some examples, each of UE 301A, UE 301B, and UE 301C may be used as Figure 1 101A, UE 101B, or UE 101C).

[0061] The wireless communication system 300 may support sidelink communication. For example, UE 301B may perform sidelink communication with UE 301A and UE 301C respectively. In some embodiments of the present disclosure, UE 301A may initiate a procedure for establishing a connection with UE 301C via UE 301B (i.e., UE to UE relay). More details about this procedure will be described below. After this procedure, UE 301A may communicate with UE 301C via relay UE (i.e., UE 301B). In some embodiments of the present application, UE 301A may perform unicast transmission with UE 301C via UE 301B. In some embodiments of the present application, UE 301A may perform multicast transmission and broadcast transmission via UE 301B.

[0062] In the case of unicast transmission between a pair of UEs (e.g., UE 301A and UE 301C or UE 301A and UE 301B), for each PC5-RRC connection, one sidelink SRB may be used to transmit PC5 signaling (PC5-S) messages before PC5-S security has been established. In addition, one sidelink SRB may be used to transmit PC5-S messages to establish PC5-S security. Additionally, after PC5-S security has been established, one sidelink SRB may be used to transmit protected PC5-S messages; and one sidelink SRB may be used to transmit protected PC5-RRC signaling. Typically, PC5-RRC signaling is sent only after PC5-S security has been established.

[0063] For a pair of UEs performing unicast communication (e.g., UE 301A and UE 301C or UE 301A and UE 301B), the PC5-S connection of the UE-UE relay link and the PC5-RRC connection of the UE-UE relay link may be one-to-one mapping. In other words, each PC5-S connection for the relay link may be associated with a corresponding PC5-RRC connection for the relay link. The PC5-RRC signaling exchange may be initiated after the PC5-S initial connection is established. The RRC layer may be informed of the release of the PC5-S connection, and may release the associated PC5-RRC connection and the corresponding sidelink SRB and sidelink DRB.

[0064] Figure 4 An exemplary procedure 400 for establishing a connection via a UE-to-UE relay according to some embodiments of the present application is described. The details described in all the above embodiments of the present disclosure are applicable to Figure 4 The embodiments shown in .

[0065] refer to Figure 4 In step 411, UE 401A performs sidelink communication with UE 401B. In other words, a PC5-RRC connection has been established between UE 401A and UE 401B. In step 413, UE 401B performs sidelink communication with UE 401C. In other words, a PC5-RRC connection has been established between UE 401B and UE 401C. Any of UE 401A, UE 401B, and UE 401C may be within coverage or out of coverage.

[0066] An upper layer of UE 401A (i.e., a layer higher than the RRC layer in the protocol stack, such as an application layer) may request to establish a connection with another UE (e.g., UE 401C). However, UE 401C may not be in the vicinity of UE 401A, and therefore a direct side link between UE 401A and UE 401C cannot be established. In this case, UE 401A (i.e., the source UE) may initiate a procedure for establishing a connection with UE 401C (i.e., the destination UE) via a UE-to-UE relay (e.g., UE 401B). Although in Figure 4 A single relay node between the source UE and the destination UE is depicted in , but it is contemplated that any number of relay nodes may be included.

[0067] In some embodiments of the present disclosure, the RRC establishment request establishment procedure may not be required to establish this connection, and a relatively simple procedure may be used. For example, a procedure similar to the sidelink RRC reconfiguration procedure 200 mentioned above may be used to establish a relay connection. In this scenario, a new message may be required to distinguish whether the UE intends to establish a PC5-RRC connection or intends to establish a relay connection. For example, an RRC reconfiguration sidelink via a relay message may be used to establish a relay connection.

[0068] In some embodiments of the present disclosure, the UE may use separate messages (e.g., an RRC reconfiguration sidelink message and an RRC reconfiguration sidelink via relay message) to establish a PC5-RRC connection and a relay connection, respectively.

[0069] For example, refer to Figure 4 In step 415, UE 401A may transmit an RRC reconfiguration sidelink via relay message to a relay UE (e.g., UE 401B). The RRC reconfiguration sidelink via relay message may include an identification of a destination UE (e.g., UE 401C) with which UE 401A (i.e., the source UE) intends to establish a connection. The RRC reconfiguration sidelink via relay message may be delivered to a lower layer (e.g., a media access control (MAC) layer and a physical layer) of UE 401A, where the identification of UE 401A (i.e., the source UE) may be added. The RRC reconfiguration sidelink via relay message may be transmitted on a signaling radio bearer (SRB) on which the RRC reconfiguration sidelink information message is transmitted.

[0070] UE 401B (i.e., relay UE) may recognize that, unlike an RRC reconfiguration sidelink message used to establish a PC5-RRC connection, for example, between UE 401A and UE 401B, an RRC reconfiguration sidelink via a relay message is used to establish a relay connection. For example, UE 401B may recognize that the target or destination of the RRC reconfiguration sidelink via a relay message is not UE 401B, and may find itself acting as a relay node. In step 417, UE 401B may transmit the RRC reconfiguration sidelink to the destination UE (e.g., UE 401C) via a relay message. The RRC reconfiguration sidelink via a relay message may include one or both of an identification of the destination UE (UE 401C) and an identification of the source UE (UE 401A).

[0071] In step 421, in response to the RRC reconfiguration sidelink via relay message, UE 401C may transmit an RRC response to UE 401B. The RRC response may include an identification of the source UE of the RRC reconfiguration sidelink via relay message as an identification of the destination UE of the RRC response. In step 423, UE 401B may transmit an RRC response to UE 401A. The RRC response may include RRC reconfiguration via relay message complete in the case of successful establishment of the relay connection. In the case of a relay connection failure, the RRC response may include RRC reconfiguration via relay message failure.

[0072] In some embodiments of the present disclosure, the UE may use the same message to establish a PC5-RRC connection and a relay connection, rather than transmitting separate messages (e.g., RRC reconfiguration sidelink via relay message and RRC reconfiguration sidelink message). For example, the UE may transmit an RRC reconfiguration sidelink message to establish a PC5-RRC connection or a relay connection. In the case of a relay connection, the RRC reconfiguration sidelink via relay message may be included in the RRC reconfiguration sidelink message.

[0073] For example, still refer to Figure 4 In step 415, UE 401A may transmit an RRC reconfiguration side link message to a relay UE (e.g., UE 401B). The RRC reconfiguration side link via the relay message and the identity of the source UE (e.g., UE 401A) of the RRC reconfiguration side link via the relay message may be encapsulated in the RRC reconfiguration side link message. In some embodiments of the present disclosure, the RRC reconfiguration side link message may include a container, which includes the RRC reconfiguration side link via the relay message and the identity of the source UE. In some embodiments of the present disclosure, the RRC reconfiguration side link message may include the identity of the destination UE (e.g., UE 401C), and UE 401A (i.e., the source UE) intends to establish a connection with the destination UE.

[0074] UE 401B may recognize that the target or destination of the RRC reconfiguration side link via the relay message is not UE 401B, and there is no need to decode the RRC reconfiguration side link message via the relay message. In step 417, UE 401B may transmit the RRC reconfiguration side link via the relay message to the destination UE (e.g., UE 401C). For example, the RRC reconfiguration side link via the relay message may be encapsulated in another RRC reconfiguration side link message, which may include a container in the RRC reconfiguration side link message received from UE 401A. In some embodiments of the present disclosure, the other RRC reconfiguration side link message may include an identifier of the destination UE (e.g., UE 401C), and UE 401A (i.e., the source UE) intends to establish a connection with the destination UE.

[0075] In step 421, in response to the RRC reconfiguration sidelink via relay message, UE 401C may transmit an RRC response to UE 401B. The RRC response may include an identifier of the source UE (e.g., UE 401A) of the RRC reconfiguration sidelink via relay message as an identifier of the destination UE of the RRC response. In step 423, UE 401B may transmit an RRC response to the corresponding UE (e.g., UE 401A). The RRC response may include RRC reconfiguration via relay message completion or RRC reconfiguration via relay message failure, depending on whether the relay connection is successfully established.

[0076] For example, in step 421, UE 401C may transmit an RRC reconfiguration complete side link message #1 (or an RRC reconfiguration failure side link message #1) to UE 401B, which may encapsulate an RRC reconfiguration complete via a relay message (or an RRC reconfiguration failure via a relay message). The identifier of UE 401C may also be encapsulated in the RRC reconfiguration complete side link message #1 (or the RRC reconfiguration failure side link message #1). The RRC reconfiguration complete side link message #1 (or the RRC reconfiguration failure side link message #1) may include the identifier of UE 401A.

[0077] In step 423, UE 401B may transmit an RRC reconfiguration complete side link message #2 (or RRC reconfiguration failure side link message #2) to UE 401A, which may encapsulate the RRC reconfiguration completion via a relay message (or the RRC reconfiguration failure via a relay message). UE 401C may encapsulate the RRC reconfiguration complete side link message #2 (or the RRC reconfiguration failure side link message #2). The RRC reconfiguration complete side link message #2 (or the RRC reconfiguration failure side link message #2) may include the identifier of UE 401A.

[0078] In some embodiments of the present disclosure, in response to transmitting the RRC reconfiguration side link via relay message, UE401A may start a timer (timer A) to control the establishment procedure of the relay connection. Timer A is different from the timer (e.g., T400) used to control the side link RRC reconfiguration procedure. UE 401A may stop timer A in response to receiving a response to the RRC reconfiguration side link via relay message (e.g., RRC reconfiguration via relay message complete or RRC reconfiguration via relay message failed). In response to the expiration of timer A or the reception of the RRC reconfiguration failure side link via relay message, UE 401A may consider that a failure has occurred on the radio link.

[0079] In some embodiments of the present disclosure, in response to the expiration of timer A or the reception of an RRC reconfiguration failure sidelink via a relay message, UE 401A may perform a sidelink reconfiguration via an original relay UE (e.g., UE 401B) or a different UE (not in Figure 4 ) waits for a certain period of time before transmitting another RRC reconfiguration sidelink via relay message.

[0080] Those skilled in the art will appreciate that the sequence of operations in the exemplary process 400 may be changed, and some operations in the exemplary process 400 may be eliminated or modified without departing from the spirit and scope of the present disclosure.

[0081] Figure 5 A schematic diagram illustrating a wireless communication system 500 according to some embodiments of the present application.

[0082] As in Figure 5 As shown in FIG. 5 , the wireless communication system 500 may include one BS (eg, BS 502) and some UEs (eg, UE 501A and UE 301B). Figure 5 A specific number of UEs and BSs are depicted in FIG. 5 , but it is contemplated that any number of UEs may be included in the wireless communication system 500 .

[0083] Reference Figure 5 , UE 501B may be within the coverage of BS 502, and UE 501A may be outside the coverage. In some examples, UE 501B may be used as Figure 1 1A or UE 101B shown in FIG. 1 , and UE 501A can be used as Figure 1 UE 101C shown in FIG.

[0084] The wireless communication system 500 may support sidelink communication. For example, UE 501B may be in sidelink communication with UE 501A. In some embodiments of the present disclosure, UE 501A may initiate a procedure for establishing a connection with BS 502 via UE 501B (i.e., UE to network relay). More details about this procedure will be described below. After this procedure, UE 501A may access BS 502 via UE 501B. UE 501A and BS 502 may establish an RRC connection between them, and UE 501A may have an RRC state, such as RRC_IDLE, RRC_INACTIVE state, and RRC_CONNECTED state.

[0085] Figure 6 An exemplary procedure 600 for establishing a connection via a UE to a network relay according to some embodiments of the present application is described. The details described in all the above embodiments of the present disclosure are applicable to Figure 6The procedure 600 may also be applied to a UE-to-UE relay scenario. For example, a UE may use the procedure 600 to establish a connection with another UE via a UE-to-UE relay.

[0086] refer to Figure 6 In step 611, UE 601A performs sidelink communication with UE 601B. In other words, a PC5-RRC connection has been established between UE 601A and UE 601B. In step 613, UE 601B is accessing BS 602. In other words, a Uu-RRC connection has been established between UE 601B and BS 602.

[0087] UE 601A may want to access a BS in order to, for example, reach a server in a PDN network. However, UE 601A is outside the coverage of any BS. In this case, UE 601A (i.e., source UE or remote UE) may initiate a procedure for establishing a connection with a BS (e.g., BS 602) via a UE-to-network relay (e.g., UE 601B). Figure 6 A single relay node between the source UE and the BS is depicted in FIG. 1 , but it is contemplated that any number of relay nodes may be included.

[0088] For example, refer to Figure 6 In step 615, UE 601A may transmit an RRC establishment request message to UE 601B. In some embodiments of the present disclosure, the RRC establishment request message may include an initial UE identifier (e.g., ng-5G-S-TMSI-Part1) and an establishment reason (e.g., "emergency", "high priority access", "mt-access", "mo-signaling", "mo-data", "mo-voice call", "mo-video call", "mo-SMS", "mps-priority access", "mcs-priority access"). In some embodiments of the present disclosure, the RRC establishment request message may include an identifier of UE 601A, which may be a 5G S-temporary mobile subscription identifier (5G-S-TMSI), a layer 2 identifier, or a simplified layer 2 identifier. The upper layer of the UE (i.e., a layer higher than the RRC layer) may specify a layer 2 identifier of the UE, which may include 24 bits. As mentioned above, the identifier of UE 601A in the RRC establishment request message may include a simplified layer 2 identifier, which may include a portion of the 24-bit layer 2 UE ID (e.g., 10 bits).

[0089] In some embodiments of the present disclosure, the RRC setup request message may indicate its target or destination. In some instances, the RRC setup request message may indicate whether it is used to establish a relay connection via a UE-to-network relay or a UE-to-UE relay. For example, the RRC setup request message may include an indicator indicating that the destination of the RRC setup request message is a UE or a BS. In some examples, the indicator may indicate an identifier of the destination UE, an identifier of the BS (e.g., a cell ID of the BS), or a predefined value indicating that the destination of the RRC setup request message is a UE or a BS. In some instances, the RRC setup request message may not include an explicit indicator for indicating its destination, which may indicate that the destination of the RRC setup request message is a BS.

[0090] exist Figure 6 In the exemplary procedure shown in , the destination of the RRC setup request message is a BS (e.g., BS 602). The RRC setup request message transmitted by UE 601A may include an explicit indicator as described above to indicate that the destination of the RRC setup request message is a BS or may not include an explicit indicator. After receiving the RRC setup request message from UE 601A, UE 601B may recognize that the RRC setup request message is for the BS. Figure 6 In the exemplary procedure shown in FIG, UE 601B is in coverage, so UE 601B may transmit an RRC setup request message to its serving BS (e.g., BS 602) in step 617. In some other examples, UE 601B may be out of coverage, and the RRC setup request message may skip more than one relay node before it reaches the BS.

[0091] Still reference Figure 6 In some instances, UE 601B may forward the RRC setup request message from UE 601A to BS 602. In some other instances, UE 601B may transmit another RRC setup request message based on the RRC setup request message from UE 601A to BS 602. The another RRC setup request message may include an identification of the remote UE (UE 601A), as indicated in the RRC setup request message from UE 601A.

[0092] In some embodiments of the present disclosure, UE 601B may forward or transmit the RRC setup request message to BS 602 on signaling radio bearer 1 (SRB1) or signaling radio bearer 2 (SRB2). In some embodiments of the present disclosure, UE 601B may be connected to a MN (e.g., BS 602) and a SN (not in Figure 6). In the event of an MCG failure at UE 601B, UE 601B may forward or transmit an RRC setup request message on signaling radio bearer 3 (SRB3). That is, the RRC setup request message may be transmitted to the SN on SRB3, and the SN may forward it to the MN (e.g., BS 602) via an Xn interface.

[0093] After receiving the RRC setup request message, BS 602 may respond to the message and may also need to configure the bearer mapping to the relay UE (i.e., UE 601B). In step 619, in response to the RRC setup request message, BS 602 may transmit an RRC reconfiguration message to UE 601B. The RRC reconfiguration message may include bearer mapping information for the relay UE (i.e., UE 601B) and a response message to the source UE (i.e., UE 601A) of the RRC setup request message. The RRC reconfiguration message may also include an identifier of UE 601A, because the bearer mapping information and the response message are UE-specific. In some embodiments of the present disclosure, the response message may be encapsulated in the RRC reconfiguration message. For example, the RRC reconfiguration message may contain a container containing the response message.

[0094] In some embodiments of the present disclosure, BS 602 may receive more than one RRC setup request message via relay UE 601B. In these embodiments, the RRC reconfiguration message transmitted from BS 602 to UE 601B may include more than one response message. For example, in addition to UE 601A, UE#4 (not in Figure 6 601B) may also transmit an RRC setup request message to BS 602 via UE 601B. The RRC reconfiguration message transmitted from BS 602 to UE 601B may include a response message to UE 601A and a response message to UE#4. The RRC reconfiguration message may also include mapping information associated with UE 601A and UE#4 of UE 601B and the identities of UE 601A and UE#4.

[0095] UE 601B may configure the bearer between UE 601B and BS 602 and the bearer between UE 601B and UE 601A according to the mapping information in the RRC reconfiguration message. In step 621, UE 601B may transmit a response message included (e.g., encapsulated) in the RRC reconfiguration message to the corresponding UE (e.g., UE 601A). In some embodiments of the present disclosure, the response message may be an RRC setup response message. In these embodiments, in response to the response message, UE 601A may transmit an RRC setup complete message to BS 602 via relay UE 601B. The RRC setup complete message may include an identifier of UE 601A (i.e., the source UE of the RRC setup complete message). For example, in step 623 (indicated as an option by a dotted arrow), UE 601A may transmit the RRC setup complete message to UE 601B. At step 625 (indicated as an option by the dashed arrow), UE 601B may forward the RRC Setup Complete message to BS 602 .

[0096] In some embodiments of the present disclosure, the response message may be a rejection message. The rejection message may indicate a time period. The UE 601A may wait for the time period before transmitting another RRC setup request message to the BS via the new relay UE.

[0097] Those skilled in the art will appreciate that the sequence of operations in the exemplary procedure 600 may be changed, and some operations in the exemplary procedure 600 may be eliminated or modified without departing from the spirit and scope of the present disclosure. For example, in the case where a UE establishes a connection with another UE via a UE-to-UE relay using the procedure 600, an RRC setup complete message transmitted from the UE to the other UE may include an identification of the other UE.

[0098] Figure 7 An example block diagram illustrating an apparatus 700 according to some embodiments of the present disclosure. The apparatus 700 may be a BS or a UE.

[0099] refer to Figure 7 , the apparatus 700 may include at least one non-transitory computer-readable medium 702, at least one receiving circuit system 704, at least one transmitting circuit system 706, and at least one processor 708. In some embodiments of the present application, the at least one receiving circuit system 704 and the at least one transmitting circuit system 706 may be integrated into at least one transceiver. At least one processor 708 may be coupled to the at least one non-transitory computer-readable medium 702, the at least one receiving circuit system 704, and the at least one transmitting circuit system 706. In some embodiments of the present disclosure, the apparatus 700 may further include an input device, a memory, and / or other components.

[0100] In some embodiments of the present disclosure, at least one non-transitory computer-readable medium 702 may store computer-executable instructions thereon to cause at least one processor 708 to implement operations, steps, or methods as described above with respect to the UE.

[0101] For example, the computer executable instructions, when executed, cause at least one processor 708 to interact with at least one receiving circuit system 704 and at least one transmitting circuit system 706 to perform Figures 1 to 6 The steps regarding the UE are described in .

[0102] In some examples, at least one transmission circuit system 706 may transmit an RRC reconfiguration side link via a relay message on the side link. At least one processor 708 may start a timer in response to the transmission of the RRC reconfiguration side link via a relay message. At least one receiving circuit system 704 may receive an RRC reconfiguration completion side link via a relay message or an RRC reconfiguration failure side link via a relay message in response to the RRC reconfiguration side link via a relay message. At least one processor 708 may stop a timer in response to the reception of the RRC reconfiguration completion side link via a relay message or the RRC reconfiguration failure side link via a relay message.

[0103] In some embodiments of the present disclosure, at least one non-transitory computer-readable medium 702 may store computer-executable instructions thereon to cause at least one processor 708 to implement operations, steps, or methods related to the BS as described above. For example, when the computer-executable instructions are executed, the at least one processor 708 interacts with at least one receiving circuit system 704 and at least one transmitting circuit system 706 to perform Figure 1 and 4 Go to the steps described in 6 regarding BS.

[0104] Those of ordinary skill in the art will appreciate that the steps of the methods described in conjunction with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module 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 steps of the methods may reside as one or any combination or set of codes and / or instructions on a non-transitory computer-readable medium that may be incorporated into a computer program product.

[0105] Although the present disclosure has been described with specific embodiments of the present disclosure, it is apparent that many alternatives, modifications and variations may be apparent to those skilled in the art. For example, in other embodiments, the various components of the embodiments may be interchangeable, added or replaced. In addition, all elements of each figure are not necessary for the operation of the disclosed embodiments. For example, a person of ordinary skill in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure set forth herein are intended to be illustrative, rather than restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0106] In this document, the term "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements not only comprises the elements, but also may comprise other elements not explicitly listed or inherent to the process, method, article or equipment. In the absence of more constraints, the elements beginning with "one" or the like do not exclude the presence of additional equivalent elements in the process, method, article or equipment comprising the elements. In addition, the term "another" is defined as at least the second or more. As used herein, the term "having" and the like are defined as "comprising".

Claims

1. A method for wireless communication, comprising: At a first user equipment UE, transmitting a radio resource control RRC establishment request message on a side link between the first UE and the second UE, wherein the RRC establishment request message includes an identifier of the first UE and the destination of the RRC establishment request message is a base station BS; receiving an RRC setup response message in response to the RRC setup request message; and transmitting an RRC setup complete message, wherein the RRC setup complete message includes the identifier of the first UE, The bearer between the first UE and the second UE is configured based on an RRC reconfiguration message from the BS to the second UE. 2 . The method according to claim 1 , wherein, in a case where the RRC setup request message does not indicate the destination of the RRC setup request message, the destination of the RRC setup request message is the BS. 3 . The method according to claim 1 , wherein the RRC setup request message further comprises an indicator indicating that the destination of the RRC setup request message is the base station BS.

4. The method according to claim 1, wherein the identifier of the first UE is a 5G S-Temporary Mobile Subscription Identifier 5G-S-TMSI, a layer 2 identifier or a simplified layer 2 identifier.

5. A method for wireless communication, comprising: At the second user equipment UE, receiving a first radio resource control RRC establishment request message on a side link, wherein the first RRC establishment request message includes an identifier of the first UE and the destination of the first RRC establishment request message is a base station BS; In response to the first RRC establishment request message, transmitting an RRC establishment response message to the first UE; receiving an RRC setup complete message from the first UE, wherein the RRC setup complete message includes the identifier of the first UE; and An RRC reconfiguration message is received from the BS in response to the first RRC establishment request message, wherein the RRC reconfiguration message includes the identifier of the first UE and bearer mapping information of the second UE.

6. The method according to claim 5, wherein the identifier of the first UE is a 5G S-Temporary Mobile Subscription Identifier 5G-S-TMSI, a layer 2 identifier or a simplified layer 2 identifier. 7 . The method according to claim 5 , wherein, in a case where the first RRC setup request message does not indicate the destination of the first RRC setup request message, the destination of the first RRC setup request message is the BS. 8 . The method according to claim 5 , wherein the first RRC setup request message further includes an indicator indicating that the destination of the first RRC setup request message is the BS.

9. The method according to claim 7, further comprising: A second RRC establishment request message is transmitted to the BS, wherein the second RRC establishment request message includes the identifier of the first UE.

10. The method according to claim 8, further comprising: A second RRC establishment request message is transmitted to the BS, wherein the second RRC establishment request message includes the identifier of the first UE.

11. A method for wireless communication, comprising: receiving, at a base station BS, from a second user equipment UE, a radio resource control RRC setup request message including an identification of the first UE; In response to the RRC establishment request message, transmitting an RRC establishment response message to the first UE; receiving an RRC setup complete message from the first UE, wherein the RRC setup complete message includes the identifier of the first UE; and In response to the RRC establishment request message, an RRC reconfiguration message is transmitted to the second UE, wherein the RRC reconfiguration message includes the identifier of the first UE and the bearer mapping information of the second UE.

12. The method according to claim 11, wherein the identifier of the first UE is a 5G S-Temporary Mobile Subscription Identifier 5G-S-TMSI, a layer 2 identifier or a simplified layer 2 identifier.

13. The method according to claim 11, wherein the RRC setup request message is received on signaling radio bearer 1 SRB1 or signaling radio bearer 2 SRB2, or When a master cell group (MCG) failure occurs on a link between the second UE and another BS, the RRC establishment request message is received via another BS serving the second UE.

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