Method and device for path switching

Abstract

The embodiment of the invention relates to a method and equipment for path switching in a communication system. In accordance with some embodiments of the present disclosure, a UE may: communicate with a BS via a relay node; receiving, from the BS via the relay node, an RRC reconfiguration message for DAPS path switching from a source connection to a target connection; and starting a timer for path switching in response to receiving the RRC reconfiguration message.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to communication techniques, and more particularly, to path switching in a communication system. Background Art

[0002] Wireless communication systems are widely deployed to provide various telecommunication services, such as telephony, video, data, messaging, broadcast, 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 wireless communication system described above, 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 communication, in which devices (e.g., UEs) that are relatively close to each other may communicate directly with each other via a sidelink, rather than being linked by a BS. A sidelink-based relay function may be supported in a communication network. For example, a UE that supports sidelink communication may be used as a relay node to extend the coverage of a BS. A UE outside or within the coverage may communicate with the BS via a relay node (e.g., a relay UE). In the context of the present disclosure, a UE that serves as a relay between another UE and a BS may be referred to as a UE-to-network (U2N) relay.

[0005] There is a need to efficiently perform communication in a communication system supporting U2N relay. Summary of the invention

[0006] Some embodiments of the present disclosure provide a user equipment (UE). The UE may include: a transceiver; and a processor coupled to the transceiver. The processor may be configured to: communicate with a base station (BS) via a relay node; receive a radio resource control (RRC) reconfiguration message for a dual active protocol stack (DAPS) path switch from a source connection to a target connection from the BS via the relay node; and start a timer for the path switch in response to receiving the RRC reconfiguration message.

[0007] Some embodiments of the present disclosure provide a relay node. The relay node may include: a transceiver; and a processor coupled to the transceiver. The processor may be configured to: establish a PC5 connection for a link between a user equipment (UE) and the relay node, wherein the UE communicates with a base station (BS) via the relay node; and receive information associated with a dual active protocol stack (DAPS) path switch for the UE from the BS or the UE.

[0008] In some embodiments of the present disclosure, the information may be received from the BS and indicate at least one of: whether bearers associated with the relay node and the UE should be suspended or continued; or a DAPS path switch is performed at the UE.

[0009] In some embodiments of the present disclosure, in order to indicate whether a bearer associated with the relay node and the UE should be suspended or continued, the information may include an indication indicating whether the bearer is associated with the DAPS path switch.

[0010] In some embodiments of the present disclosure, the processor may be further configured to perform at least one of the following in response to receiving the information: continuing communication associated with the bearer when the information indicates that the bearer is associated with the DAPS path switch; or releasing data associated with the bearer when the information indicates that the bearer is not associated with the DAPS path switch.

[0011] In some embodiments of the present disclosure, the processor may be further configured to transmit a PC5 unicast link release indication to the UE in response to one of the following conditions after receiving the information: RLF between the relay node and the BS; reception of an RRC reconfiguration message containing a synchronized configuration at the relay node; cell reselection at the relay node; RRC connection establishment failure or RRC recovery failure at the relay node; initiation of a reconstruction process at the relay node; a successful reconstruction process at the relay node; a failed reconstruction process at the relay node; and successful switching of the relay node.

[0012] In some embodiments of the present disclosure, the information may be received from the UE and indicate the fallback of the DAPS path switch. In some embodiments of the present disclosure, the information may be received from the BS and indicate the fallback of the DAPS path switch and the ID of the UE.

[0013] In some embodiments of the present disclosure, the information may be received from the UE via an RRC layer or a Sidelink Relay Adaptation Protocol (SRAP) layer. In some embodiments of the present disclosure, the information may be received from the BS via an RRC message.

[0014] In some embodiments of the present disclosure, the processor may be further configured to restore bearers not associated with the DAPS path switch back to a source configuration in response to receiving the information.

[0015] Some embodiments of the present disclosure provide a base station (BS). The BS may include: a transceiver; and a processor coupled to the transceiver. The processor may be configured to: transmit a radio resource control (RRC) reconfiguration message for a dual active protocol stack (DAPS) path switch to a user equipment (UE) via a relay node; and transmit information associated with the DAPS path switch to the relay node.

[0016] In some embodiments of the present disclosure, the information may indicate at least one of: whether a bearer associated with the relay node and the UE should be suspended or continued; or a DAPS path switch should be performed at the UE.

[0017] In some embodiments of the present disclosure, in order to indicate whether a bearer associated with the relay node and the UE should be suspended or continued, the information may include an indication indicating whether the bearer is associated with the DAPS path switch.

[0018] In some embodiments of the present disclosure, the processor may be configured to receive a failure indication of the DAPS path switch from the UE. The information may be transmitted in response to receiving the failure indication and indicate the fallback of the DAPS path switch and the ID of the UE. In some embodiments of the present disclosure, the information may be transmitted via an RRC message.

[0019] In some embodiments of the present disclosure, the processor may be further configured to receive capability information indicating whether the UE supports DAPS path switching.

[0020] The capability information may indicate at least one of: whether the UE supports a path switch from an indirect path to a direct path; or whether the UE supports a path switch from an indirect path to another indirect path.

[0021] Some embodiments of the present disclosure provide a method performed by a user equipment (UE). The method may include: communicating with a base station (BS) via a relay node; receiving a radio resource control (RRC) reconfiguration message for a dual active protocol stack (DAPS) path switch from a source connection to a target connection from the BS via the relay node; and starting a timer for the path switch in response to receiving the RRC reconfiguration message.

[0022] Some embodiments of the present disclosure provide a method performed by a relay node. The method may include: establishing a PC5 connection for a link between a user equipment (UE) and the relay node, wherein the UE communicates with a base station (BS) via the relay node; and receiving information associated with a dual active protocol stack (DAPS) path switch for the UE from the BS or the UE.

[0023] Some embodiments of the present disclosure provide a method performed by a relay node. The method may include: transmitting a radio resource control (RRC) reconfiguration message for a dual active protocol stack (DAPS) path switch to a user equipment (UE) via the relay node; and transmitting information associated with the DAPS path switch to the relay node.

[0024] Some embodiments of the present disclosure provide a device. According to some embodiments of the present disclosure, the device may include: 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 at least one non-transitory computer-readable medium and the computer-executable instructions may be configured to cause the device to perform the method according to some embodiments of the present disclosure with the at least one processor.

[0025] Embodiments of the present disclosure provide technical solutions for facilitating and improving implementation of various communication technologies (e.g., 5G NR). BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To describe the manner in which the advantages and features of the present disclosure can be obtained, the description of the present disclosure is presented by reference to specific embodiments of the present disclosure illustrated in the accompanying drawings. These drawings depict only exemplary embodiments of the present disclosure and therefore should not be considered limiting of its scope.

[0027] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present disclosure;

[0028] Figure 2 A schematic diagram illustrating a relay-based wireless communication system according to some embodiments of the present disclosure;

[0029] Figure 3 A flowchart illustrating an exemplary notification message process according to some embodiments of the present disclosure;

[0030] Figure 4 A schematic diagram illustrating a wireless communication system according to some embodiments of the present disclosure;

[0031] Figures 5 to 9 A flowchart illustrating an exemplary process of wireless communication according to some embodiments of the present disclosure; and

[0032] Fig.10 A block diagram illustrating an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0033] 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 implemented by different embodiments intended to be included in the spirit and scope of the present disclosure.

[0034] Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. For ease of 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 considered 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 cited in the present disclosure may be changed, which should not affect the principles of the present disclosure.

[0035] Figure 1 A schematic diagram illustrating a wireless communication system 100 according to some embodiments of the present disclosure.

[0036] like Figure 1 As shown in , the wireless communication system 100 can support sidelink communication. The sidelink communication supports UE-to-UE direct communication. In the context of the present disclosure, the sidelink communication can be classified according to the wireless communication technology adopted. For example, the sidelink communication can include NR sidelink communication and V2X sidelink communication.

[0037] NR sidelink communication (e.g., specified in 3GPP TS 38 series specifications) may refer to access stratum (AS) functions that implement at least vehicle-to-everything (V2X) communication between neighboring UEs using NR technology but without traversing any network nodes. V2X sidelink communication (e.g., specified in 3GPP TS 36 series specifications) may refer to AS functions that implement V2X communication between neighboring UEs using Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) (E-UTRA) technology but without traversing any network nodes. However, if not specified, "sidelink communication" may refer to NR sidelink communication, V2X sidelink communication, or any sidelink communication that employs other wireless communication technologies.

[0038] 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 .

[0039] UE and BS may support communication 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, a BS (e.g., BS102 or BS103) may be referred to as an access point, an access terminal, a base, a base unit, a macro cell, a node B, an evolved node B (eNB), a gNB, an ng-eNB, a home node B, a relay node, or a device, or described using other terms used in the art. A UE (e.g., UE 101A, UE 101B, or UE 101C) may include, for example (but not limited to), a computing device, a wearable device, a mobile device, an IoT device, a vehicle, etc. Those skilled in the art should understand that, as technology develops and advances, the terms described in the present disclosure may change, but should not affect or limit the principles and spirit of the present disclosure.

[0040] exist Figure 1 In the example of, BS102 and BS103 may be included in a next generation radio access network (NG-RAN). In some embodiments of the present disclosure, BS102 may be a gNB, and BS103 may be an ng-eNB.

[0041] UE 101A and UE 101B may be within coverage (e.g., within NG-RAN). Figure 1 As shown in FIG. 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 (e.g., out of the coverage of NG-RAN). Figure 1, UE 101C may be outside the coverage of any BS (e.g., both BS 102 and BS 103). UE 101A and UE 101B may be connected to BS 102 and BS 103, respectively, via a network interface (e.g., a Uu interface as 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. The link established between a UE (e.g., UE 101A) and a BS (e.g., BS 102) may be referred to as a Uu link. BS 102 and BS 103 may be connected to each other via a network interface (e.g., an Xn interface as specified in a 3GPP standard document). UE 101A, UE 101B, and UE 101C may be connected to each other via, for example, a PC5 interface 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 PC5RRC. A link established between two UEs (eg, UE 101A and UE 101B) may be referred to as a PC5 link.

[0042] Support for V2X services via the PC5 interface may be provided, for example, by NR sidelink communications and / or V2X sidelink communications. NR sidelink communications 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 on the PC5 interface are supported. For example, UE 101A within the coverage of BS 102 may perform sidelink transmission and reception (e.g., sidelink unicast transmission, sidelink multicast transmission, or sidelink broadcast transmission) on the PC5 interface. UE 101C outside the coverage of both BS 102 and BS 103 may also perform sidelink transmission and reception on the PC5 interface.

[0043] A UE supporting sidelink communication and / or V2X communication may be referred to as a V2X UE. According to some other embodiments of the present disclosure, 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.

[0044] As mentioned above, a sidelink-based relay function may be supported in a communication network. Sidelink relay may provide another UE (remote UE) with a connection to the network. In some embodiments of the present disclosure, UE-to-network relay is supported. For example, a UE within coverage that communicates with a remote UE (e.g., an out-of-coverage UE or an in-coverage UE) may be used as a relay UE between a serving BS of the UE within coverage and the remote UE. Therefore, the remote UE may communicate with the BS via this relay UE. Data between the remote UE and the BS may be transmitted via the relay UE. In this scenario, the relay UE may be referred to as a serving relay for the remote UE, and the serving BS or serving cell of the relay UE may be referred to as a serving BS or serving cell of the remote UE, respectively.

[0045] The remote UE may have an RRC state, such as an RRC_IDLE state, an RRC_INACTIVE state, and an RRC_CONNECTED state as defined in the 3GPP specification. The relay UE may be in the RRC_CONNECTED state to perform relaying of unicast data. In some embodiments, in the case of a path switch, a relay UE in the RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED state may be selected as a target relay UE.

[0046] In some embodiments, for Layer 2 (L2) U2N relay operation, the following RRC state combinations may be supported:

[0047] - Both the relay UE and the remote UE may be in the RRC_CONNECTED state to perform transmission or reception of relayed unicast data; and

[0048] - The relay UE may be in RRC_IDLE, RRC_INACTIVE or RRC_CONNECTED state as long as each remote UE connected to the relay UE is in RRC_INACTIVE state or in RRC_IDLE state.

[0049] A single unicast link may be established between one relay UE and one remote UE. Traffic for remote UEs and traffic for relay UEs via a given relay UE may be separated in different Uu relay radio link control (RLC) channels. In some embodiments, for L2 U2N relaying, the remote UE may be configured to use resource allocation mode 2 only for data to be relayed.

[0050] Figure 2 Schematic diagram of a relay-based wireless communication system 200 according to some embodiments of the present disclosure. Figure 2 The embodiments shown in .

[0051] like Figure 2 As shown in FIG. 1 , a wireless communication system 200 may include a BS (eg, BS 202) and some UEs (eg, UE 201A and UE 201B). Figure 2 Although a specific number of UEs and BSs are depicted in FIG. 2 , it is contemplated that any number of UEs and BSs may be included in the wireless communication system 200. In some examples, UE 201B may be used as Figure 1 1A or UE 101B shown in FIG. 1 , and UE 201A can be used as Figure 1 UE 101C shown in FIG.

[0052] UE 201B may be within the coverage of BS 202. For example, UE 201B and BS 202 may establish an RRC connection therebetween. UE 201A may be outside the coverage of BS 202. Wireless communication system 200 may support sidelink communication. For example, UE 201B may be in sidelink communication with UE 201A. A PC5 RRC connection may be established between UE 201A and UE 201B.

[0053] In some embodiments of the present disclosure, UE 201A may initiate a process for establishing a connection with BS 202 via UE 201B (i.e., UE to network relay). For example, UE 201A may transmit an RRC establishment request to BS 202 via UE 201B. BS 202 may transmit an RRC establishment message including a response to UE 201A via UE 201B. After such a process, UE 201A may access BS 202 (e.g., a cell of BS 202) via UE 201B. This cell may be referred to as a serving cell of UE 201A. UE 201A and BS 202 may establish an RRC connection therebetween. UE 201A may also be referred to as a remote UE, and UE 201B may also be referred to as a relay UE, a sidelink relay, or a serving relay of UE 201A.

[0054] It should be understood by those skilled in the art that although Figure 2 A single relay node (e.g., UE 201B) is depicted between UE 201A and BS 202, but it is contemplated that any number of relay nodes may be included. Figure 2 UE 201A is shown out of coverage of BS 202, but it is contemplated that in some other embodiments of the present disclosure, UE 201A may be within coverage of BS 202. In these embodiments, UE 201A may be directly connected to BS 202 and / or connected to BS 202 via UE 201B.

[0055] In some embodiments of the present disclosure, a relay node (e.g., a relay UE) may declare a Uu RLF (e.g., RLF between the relay node and the BS) based on at least one of the following criteria:

[0056] - expiry of a radio problem timer that was started following an indication of a radio problem from the physical layer (if the radio problem recovers before the timer expires, the relay node stops the timer); or

[0057] - expiry of a timer that was started when a measurement report for a measurement identity for which a timer has been configured is triggered while another radio problem timer is running; or

[0058] - Random access procedure fails; or

[0059] -RLC failed.

[0060] In some embodiments of the present disclosure, in response to the declaration of Uu RLF, the relay node may transmit a notification message to the remote UE to which it is connected, which may trigger the RRC connection reestablishment for the remote UE. In some embodiments of the present disclosure, the remote UE may trigger the RRC connection reestablishment in response to detecting PC5 RLF (e.g., RLF between the relay node and the remote UE).

[0061] Figure 3 A flowchart illustrating an exemplary notification message process 300 according to some embodiments of the present disclosure. The details described in all the above embodiments of the present disclosure apply to Figure 3 The embodiments shown in .

[0062] refer to Figure 3 In operation 311, the relay node 302 may transmit a notification message to the UE 301. In some examples, the relay node 302 may be a relay UE, such as a U2N relay UE. In this scenario, the notification message may also be referred to as a "notification message for a side link".

[0063] In some embodiments of the present disclosure, the relay node 302 may initiate the exemplary process 300 when, for example, one of the following conditions is met:

[0064] - in response to a Uu RLF as described above;

[0065] - in response to receipt of an RRC reconfiguration message, such as a handover command, containing a reconfigurationWithSync information element (IE);

[0066] - In response to a cell reselection at the relay node 302;

[0067] - In response to an RRC connection failure at the relay node 302, which may include, for example, an RRC connection reject, expiration of a timer for an RRC establishment request (eg, T300 as specified in 3GPP specifications), and an RRC recovery failure.

[0068] The notification message may include a type indication (eg, "indicationType"), which may indicate that the notification message is due to one of relay Uu RLF, relay handover, relay cell reselection, and / or relay connection failure.

[0069] In some embodiments of the present disclosure, the remote UE may be switched or handed over from an indirect path (e.g., the UE indirectly accesses the source BS (or source cell) via a source relay node) to a direct path (e.g., the UE directly accesses the target BS (or target cell) without any relay node) or to another indirect path (e.g., the UE indirectly accesses the target BS (or target cell) via a target relay node).

[0070] In some embodiments of the present disclosure, during a path switch (switch or handover), the UE may release the connection with the source cell (e.g., source BS) before establishing a connection with the target cell (e.g., target BS). This may also be referred to as a "hard handover". As a result, data transmission at the source cell stops before the UE starts communicating with the target cell. This will cause an interruption, which may be critical for services that are sensitive to latency or continuity. In order to overcome the above problems, a DAPS path switch (or DAPS handover) is introduced, in which the UE maintains the source cell connection after receiving the handover command and releases the source cell connection only after successfully accessing the target cell. This may also be referred to as a "soft handover". DAPS handover can be used to reduce or avoid service interruption and thus ensure service continuity during handover. This may require the UE to simultaneously receive and transmit data at both the source cell and the target cell in a short period of time during the handover process. In the context of the present disclosure, "handover" and "path switch" are used interchangeably.

[0071] Figure 4 Schematic diagram of a wireless communication system 400 according to some embodiments of the present disclosure. Figure 4 The embodiments shown in .

[0072] refer to Figure 4 , the wireless communication system 400 may include some base stations (eg, BS 402A and BS 402B) and some UEs (eg, UE 401A and UE 401B). Figure 4A specific number of UEs and BSs are depicted in FIG. 4 , but it is contemplated that any number of UEs and BSs may be included in the wireless communication system 400. In some examples, UE 401A may be used as Figure 2 UE 201A and UE 401B shown in FIG. 4 can be used as Figure 2 UE 201B shown in FIG. 1 , and BS 402A and BS 402B may be used as Figure 2 BS202 shown in the.

[0073] UE 401A may communicate with BS 402A via UE 401B. BS 402A may decide to handover UE 401A to BS 402B. Figure 4 As shown in , DAPS switching can be performed. During DAPS switching, UE 401A maintains both the source connection and the target connection for a period of time.

[0074] Despite Figure 4 4 shows that UE 401A switches from an indirect path to a direct path via DAPS, but it is contemplated that in some other embodiments of the present disclosure, UE 401A may switch to another indirect path via DAPS. For example, BS 402A may switch UE 401A to a target relay node (e.g., a relay UE), which may access BS 402B.

[0075] It should be understood by those skilled in the art that although some of the foregoing drawings (e.g. Figure 2 and 4 ) is described with respect to relay UE, but it is considered that other types of relay nodes may be used instead of relay UE.

[0076] During a DAPS handover of a remote UE, various issues need to be addressed. For example, a solution is needed for handling a source relay node during a DAPS handover of a remote UE. For example, during a DAPS handover, a remote UE may receive various messages from a relay node. A solution is needed for handling these messages. For example, a solution is needed for handling RLF between a remote UE and a source relay node during a DAPS handover. More details about embodiments of the present disclosure will be described below in conjunction with the accompanying drawings.

[0077] Figure 5 Flowchart illustrating an exemplary process 500 for wireless communication according to some embodiments of the present disclosure. Figure 5 The embodiments shown in .

[0078] refer to Figure 5In operation 511, UE 501A may communicate with BS 502A via relay node 501B. In some embodiments, relay node 501B may be a UE (e.g., a L2 U2N relay UE). In some examples, UE 501A and relay node 501B may be used as Figure 4 UE 401A and UE 401B shown in FIG. 4 , and BS 502A and BS 502B may be used as Figure 4 BS 402A and BS 402B are shown in FIG. The remote UE may be in a connected state (eg, RRC_CONNECTED state).

[0079] In some embodiments, UE 501A may report measurement results to BS 502A based on the configuration from BS 502A. The measurement results may include measurement results for a cell or a candidate relay UE. For example, the measurement results may be transmitted from UE 501A to BS 502A via relay node 501B in operations 513 and 513'.

[0080] In some embodiments, UE 501A may report capability information to BS 502A. For example, the capability information may indicate whether UE 501A supports DAPS path switching. The path switching may be from an indirect path to a direct path or from an indirect path to another indirect path. For example, the capability information may indicate at least one of the following: whether UE 501A supports path switching from an indirect path to a direct path; or whether UE 501A supports path switching from an indirect path to another indirect path.

[0081] In operation 515, BS 502A (source BS) may determine to switch UE 501A to a target cell (e.g., to a direct path) or a target relay UE (e.g., to an indirect path) via DAPS path switching. In operation 517, BS 502A may transmit a handover request message to the target BS (e.g., BS 502B). In some embodiments, the handover request message may include information about UE 501A (e.g., UE context and UE ID).

[0082] In response to receiving the handover request message, BS 502B may permit the path switch and may transmit a handover request confirm message to BS 502A via, for example, an Xn interface in operation 519. The handover request confirm message may include an RRC reconfiguration message.

[0083] In response to receiving the handover request confirm message, BS 502A may transmit an RRC reconfiguration message including a configuration with synchronization to UE 501A via relay node 501B in operations 521 and 521'. In the case of DAPS path switching, the RRC reconfiguration message may also be referred to as "RRC reconfiguration message for DAPS path switching".

[0084] In some embodiments, according to the reconfiguration message, some bearers may be configured as DAPS bearers. These bearers may include end-to-end bearers or PC5 bearers. PC5 bearers may be associated with PC5 relay RLC channels.

[0085] In some embodiments, for non-DAPS bearers, UE 501A may perform a refresh of security and re-establishment of RLC and Packet Data Convergence Protocol (PDCP) triggered by an explicit L2 indicator.

[0086] In some embodiments, for the DAPS bearer, UE 501A may perform RLC establishment for the target cell (e.g., target primary cell (PCell)), security refresh, and PDCP reconfiguration to add encryption function, integrity protection function, and robust header compression (ROHC) function of the target cell (e.g., target PCell).

[0087] It would be advantageous if the relay node 501B was aware of the DAPS path switch.The relay node 501B may handle the buffered data for non-DAPS bearers and DAPS bearers differently.

[0088] In some embodiments of the present disclosure, BS 502A may transmit information associated with DAPS path switching to relay node 501B in operation 525 (indicated as an option by a dashed arrow). For example, the information may indicate whether a bearer associated with UE 501A and relay node 501B should be suspended or continued. In some embodiments, the information may include an indication indicating whether the bearer is associated with DAPS path switching. In some embodiments, a corresponding indication for each bearer associated with UE 501A and relay node 501B may be transmitted to relay node 501B. The bearer may be a DAPS bearer or a non-DAPS bearer, depending on whether it is indicated as being associated with a DAPS path switching. Such an indication may also be referred to as a DAPS indication.

[0089] In response to receiving the information, the relay node 501B may continue communications (eg, transmitting or receiving data) associated with the DAPS bearer. The relay node 501B may release data associated with the non-DAPS bearer.

[0090] In response to receiving the RRC reconfiguration message, UE 501A may perform a path switching procedure. For example, UE 501A may start a timer for path switching in response to receiving the RRC reconfiguration message. In the case of a handover to a target cell (e.g., a direct path), the timer may be T304 as specified in the 3GPP specification, or for a handover to a target relay node (e.g., an indirect path), the timer may be T420 as specified in the 3GPP specification.

[0091] In some embodiments of the present disclosure, when the timer for path switching is running, the notification message may be received from the relay node 501B. In some embodiments, the relay node 501B may transmit the notification message in response to one of the following conditions: RLF occurs between the relay node 501B and the BS 502A; the relay node 501B receives an RRC reconfiguration message (e.g., a handover command) including a reconfiguration with synchronization; the relay node 501B (re)selects a cell; an RRC connection establishment failure or an RRC recovery failure occurs at the relay node 501B; the relay node 501B initiates a reestablishment procedure; the relay node 501B performs a successful reestablishment procedure; the reestablishment procedure fails at the relay node 501B; and the relay node 501B successfully performs a handover procedure.

[0092] In some embodiments of the present disclosure, in response to receiving a notification message while the timer for path switching is running, UE 501A may release the source connection (e.g., the connection to BS 502A). That is, although UE 501A is performing DAPS switching, it may also release the source connection in this scenario.

[0093] In some embodiments of the present disclosure, when the timer for path switching is running, UE 501A may detect RLF of the side link between UE 501A and relay node 501B. In response to detecting RLF while the timer for path switching is running, UE 501A may release the source connection (e.g., the connection to BS 502A).

[0094] In some embodiments of the present disclosure, in response to receiving a notification message while a timer for path switching is running, UE 501A may suspend the source connection (e.g., the connection to BS 502A). In some embodiments, when the connection (e.g., Uu link) between relay node 501B and BS 502A is available or restored, UE 501A may restore the source connection.

[0095] In some embodiments of the present disclosure, BS 502A may notify relay node 501B that UE 501A performs DAPS path switching. In response to receiving such information, when the conditions for transmitting the notification message are met, relay node 501B may transmit a PC5 unicast link release indication (e.g., a PC5-S release message or a PC5-S message) instead of a notification message. In this way, UE 501A will not receive a notification message when the timer for path switching is running, and may instead receive a PC5 unicast link release indication when the timer for path switching is running.

[0096] For example, in some embodiments, in operation 525, BS 502A may transmit an indication to relay node 501B indicating that a DAPS path switch is to be performed at UE 501A. In some embodiments, BS 502A may not transmit such an explicit indication. For example, the information indicating whether a bearer is associated with a DAPS path switch as described above may implicitly indicate that a DAPS path switch is to be performed at UE 501A. In other words, the information associated with a DAPS path switch to relay node 501B may indicate at least one of: whether a bearer associated with UE 501A and relay node 501B should be suspended or continued; or that a DAPS path switch is to be performed at UE 501A.

[0097] In some embodiments of the present disclosure, when the timer for path switching is running, UE 501A may receive a PC5 unicast link release indication. In response to receiving a PC5 unicast link release indication while the timer for path switching is running, UE 501A may release a source connection (e.g., a connection to BS 502A). In some instances, the PC5 unicast link release indication may come from an upper layer (e.g., PC5-S layer) of UE 501A. In some instances, the PC5 unicast link release indication may be transmitted by relay node 501B. For example, as described above, in response to satisfying a condition for triggering a notification message, relay node 501B may transmit a PC5 unicast link release indication to UE 501A.

[0098] In operation 523, UE 501A may stop a timer for path switching. For example, when the target node of the handover is a cell, UE 501A may stop a timer for path switching (e.g., T304 as specified in the 3GPP specification) in response to successful completion of random access on the target cell. For example, when the target node of the handover is a relay node, UE 501A may stop a timer for path switching (e.g., T420 as specified in the 3GPP specification) in response to successful transmission of an RRC reconfiguration complete message to a target BS (e.g., BS 502B) via the target relay node.

[0099] In some embodiments of the present disclosure, after the timer for path switching stops (eg, before the source connection is released), a notification message may be received from the relay node 501B. The triggering conditions for the notification message as described above may also be applicable here.

[0100] In some embodiments of the present disclosure, in response to receiving a notification message after the timer for path switching stops, UE 501A may release the source connection (e.g., the connection to BS 502A). In some embodiments of the present disclosure, UE 501A may ignore the notification message received after the timer for path switching stops.

[0101] In some embodiments of the present disclosure, BS 502A may notify relay node 501B that UE 501A performs a DAPS path switch. For example, as described above with respect to operation 525, information associated with the DAPS path switch to relay node 501B may indicate at least one of the following: whether the bearer associated with UE 501A and relay node 501B should be suspended or continued; or the DAPS path switch is performed at UE 501A. In response to receiving such information, when the conditions for transmitting a notification message are met, relay node 501B may transmit a PC5 unicast link release indication (e.g., a PC5-S release message or a PC5-S message) instead of a notification message. In this way, UE 501A will not receive a notification message after the timer for path switching stops, and may instead receive a PC5 unicast link release indication after the timer for path switching stops.

[0102] In some embodiments of the present disclosure, UE 501A may receive a PC5 unicast link release indication after a timer for path switching stops. In some embodiments of the present disclosure, in response to receiving a PC5 unicast link release indication after a timer for path switching stops, UE 501A may release a source connection (e.g., a connection to BS 502A). In some embodiments of the present disclosure, UE 501A may ignore a PC5 unicast link release indication received after a timer for path switching stops. In some instances, the PC5 unicast link release indication may come from an upper layer (e.g., PC5-S layer) of UE 501A. In some instances, the PC5 unicast link release indication may be transmitted by relay node 501B. For example, as described above, in response to satisfying a condition for triggering a notification message, relay node 501B may transmit a PC5 unicast link release indication to UE 501A.

[0103] In some embodiments of the present disclosure, it may be allowed to detect whether RLF occurs between the UE 501A and the relay node 501B after the timer for path switching stops.

[0104] In some embodiments of the present disclosure, in response to UE 501A detecting RLF (or declaring RLF) of a side link between UE 501A and relay node 501B after a timer for path switching expires, UE 501A may release the source connection (e.g., the connection to BS 502A).

[0105] In some embodiments of the present disclosure, in response to UE 501A detecting RLF (or declaring RLF) of a side link between UE 501A and relay node 501B after a timer for path switching stops, UE 501A may not release the source connection (e.g., the connection to BS 502A). In other words, UE 501A may refrain from releasing the source connection in response to detecting RLF.

[0106] In some embodiments of the present disclosure, after the timer for path switching stops, UE 501A may not detect RLF on the side link between UE 501A and relay node 501B. In other words, UE 501A may prohibit detection of such RLF. In some embodiments of the present disclosure, prohibiting such RLF detection may include at least one of the following: prohibiting the performance of radio link monitoring (RLF); or prohibiting the declaration of RLF in response to the expiration of the timer (such as T400 specified in the 3GPP specification) of the side link RRC reconfiguration.

[0107] In operation 527, UE 501A may receive an RRC reconfiguration message from BS 502B. In some embodiments, an indication for releasing the source connection may be included in the RRC reconfiguration message.

[0108] In operation 529, in response to receiving the RRC reconfiguration message, UE 501A may release the source connection (e.g., if the source connection is not released). For example, UE 501A may release the PC5 RRC connection between UE 501A and relay node 501B and the Uu RRC configuration with the source cell (e.g., BS 502A).

[0109] Those skilled in the art will appreciate that the sequence of operations in exemplary process 500 may be changed, and some of the operations in exemplary process 500 may be eliminated or modified without departing from the spirit and scope of the present disclosure.

[0110] Figure 6 600 for wireless communication according to some embodiments of the present disclosure. Figure 6 The embodiments shown in .

[0111] refer to Figure 6In operation 611, UE 601A may communicate with BS 602A via relay node 601B. In some embodiments, relay node 601B may be a UE (e.g., a L2 U2N relay UE). In some examples, UE 601A and relay node 601B may be used as Figure 4 UE 401A and UE 401B shown in FIG. 4 , and BS 602A and BS 602B may be used as Figure 4 BS 402A and BS 402B are shown in FIG. The remote UE may be in a connected state (eg, RRC_CONNECTED state).

[0112] In some embodiments, UE 601A may report measurement results to BS 602A based on the configuration from BS 602A. The measurement results may include measurement results for a cell or a candidate relay UE. For example, the measurement results may be transmitted from UE 601A to BS 602A via relay node 601B in operations 613 and 613'.

[0113] In some embodiments, UE 601A may report capability information to BS 602A. For example, the capability information may indicate whether UE 601A supports DAPS path switching. The path switching may be from an indirect path to a direct path or from an indirect path to another indirect path. For example, the capability information may indicate at least one of the following: whether UE 601A supports path switching from an indirect path to a direct path; or whether UE 601A supports path switching from an indirect path to another indirect path.

[0114] In operation 615, BS 602A (source BS) may determine to switch UE 601A to a target cell (e.g., to a direct path) or a target relay UE (e.g., to an indirect path) via DAPS path switching. In operation 617, BS 602A may transmit a handover request message to the target BS (e.g., BS 602B). In some embodiments, the handover request message may include information about UE 601A (e.g., UE context and UE ID).

[0115] In response to receiving the handover request message, BS 602B may permit the path switch and may transmit a handover request confirm message to BS 602A via, for example, an Xn interface in operation 619. The handover request confirm message may include an RRC reconfiguration message.

[0116] In response to receiving the handover request confirm message, BS 602A may transmit an RRC reconfiguration message including a configuration with synchronization to UE 601A via relay node 601B in operations 621 and 621'. In the case of DAPS path switching, the RRC reconfiguration message may also be referred to as "RRC reconfiguration message for DAPS path switching".

[0117] In some embodiments, according to the reconfiguration message, some bearers may be configured as DAPS bearers. These bearers may include end-to-end bearers or PC6 bearers. PC6 bearers may be associated with PC6 relay RLC channels.

[0118] In some embodiments, for non-DAPS bearers, UE 601A may perform a refresh of security and re-establishment of RLC and Packet Data Convergence Protocol (PDCP) triggered by an explicit L2 indicator.

[0119] In some embodiments, for the DAPS bearer, UE 601A may perform RLC establishment for the target cell (e.g., target primary cell (PCell)), security refresh, and PDCP reconfiguration to add encryption function, integrity protection function, and robust header compression (ROHC) function of the target cell (e.g., target PCell).

[0120] It would be advantageous if the relay node 601B was aware of the DAPS path switch.The relay node 601B may handle the buffered data for non-DAPS bearers and DAPS bearers differently.

[0121] In some embodiments of the present disclosure, BS 602A may transmit information associated with DAPS path switching to relay node 601B in operation 625 (indicated as an option by a dotted arrow). Figure 5 The information described as being associated with a DAPS path switch may be applicable here. For example, the information may indicate whether a bearer associated with the UE 601A and the relay node 601B should be suspended or continued. In some embodiments, the information may include an indication indicating whether the bearer is associated with a DAPS path switch. In some embodiments, a corresponding indication for each bearer associated with the UE 601A and the relay node 601B may be transmitted to the relay node 601B. The bearer may be a DAPS bearer or a non-DAPS bearer, depending on whether it is indicated as being associated with a DAPS path switch. Such an indication may also be referred to as a DAPS indication.

[0122] In response to receiving the information, the relay node 601B may continue communications (eg, transmitting or receiving data) associated with the DAPS bearer. The relay node 601B may release data associated with the non-DAPS bearer.

[0123] In response to receiving the RRC reconfiguration message, UE 601A may perform a path switching procedure. For example, UE 601A may start a timer for path switching in response to receiving the RRC reconfiguration message. In the case of a handover to a target cell (e.g., a direct path), the timer may be T304 as specified in the 3GPP specification, or for a handover to a target relay node (e.g., an indirect path), the timer may be T420 as specified in the 3GPP specification.

[0124] In operation 623, the timer for path switching may expire. In some embodiments, UE 601A may fall back to the source connection in response to the expiration of the timer for path switching. In some embodiments, UE 601A may revert back to the UE configuration used in the source connection in response to the expiration of the timer for path switching. In some embodiments, UE 601A may perform data transmission or reception via the source connection after the fallback.

[0125] In some embodiments, the UE 601A may transmit a failure indication of the DAPS path switch to the BS 602A via the relay node 601B in operations 627 and 627'. For example, the failure indication may be transmitted via a failure information message.

[0126] It would be advantageous if the relay node 601B knew about the fallback of the UE 601A (e.g., failure of DAPS path switching or fallback of DAPS path switching) so that the relay node 601B can recover the configuration. In some embodiments of the present disclosure, the BS 602A or UE 601A may inform the relay node 601B of such information.

[0127] For example, in operation 631 (indicated as an option by a dashed arrow), UE 601A may transmit an indication to relay node 601B indicating a fallback of UE 601A. In some examples, the indication may be transmitted to relay node 601B via an RRC layer (e.g., an RRC layer for PC5). In some examples, the indication may be transmitted to relay node 601B via a sidelink relay adaptation protocol (SRAP) layer.

[0128] For example, in operation 633 (indicated as an option by a dashed arrow), BS 602A may transmit information associated with DAPS path switching to relay node 601B. The information may indicate the fallback of UE 601A and the ID of UE 601A. In some examples, the information may be transmitted to relay node 601B via an RRC message.

[0129] In response to receiving the indication or information indicating the fallback of UE 601A, the relay node 601B may restore the bearers not associated with the DAPS path switch (eg, non-DAPS bearers) back to the source configuration (eg, the configuration used in the source connection).

[0130] Those skilled in the art will appreciate that the sequence of operations in exemplary process 600 may be changed, and some of the operations in exemplary process 600 may be eliminated or modified without departing from the spirit and scope of the present disclosure. For example, although operation 631 is shown after operation 627, in some other embodiments, it may be before operation 627. For example, an indication indicating a fallback of UE 601A may be transmitted in response to expiration of a timer for a path switch.

[0131] Figure 7 Flowchart illustrating an exemplary process 700 for wireless communication according to some embodiments of the present disclosure. Figure 7 In some examples, the process may be performed by a UE (eg, a remote UE).

[0132] refer to Figure 7 In operation 711, the UE may communicate with the BS via the relay node. In operation 713, the UE may receive an RRC reconfiguration message for DAPS path switching from a source connection to a target connection from the BS via the relay node. In operation 715, the UE may start a timer for path switching (e.g., T304 or T420 as specified in the 3GPP specification) in response to receiving the RRC reconfiguration message.

[0133] In some embodiments of the present disclosure, the UE may perform at least one of the following: releasing the source connection in response to receiving a notification message from the relay node while the timer for path switching is running; releasing the source connection in response to detecting a radio link failure (RLF) of a side link between the UE and the relay node while the timer for path switching is running; releasing the source connection in response to receiving a PC5 unicast link release indication while the timer for path switching is running; suspending the source connection in response to receiving a notification message from the relay node while the timer for path switching is running; or resuming the suspended source connection in response to the connection between the relay node and the BS becoming available.

[0134] In some embodiments of the present disclosure, the UE may stop the timer for path switching in response to the successful completion of random access on the target cell of the DAPS path switching or the successful transmission of an RRC reconfiguration completion message. After stopping the timer for path switching, the UE may perform at least one of the following: releasing the source connection in response to receiving a notification message from the relay node; ignoring the notification message received from the relay node; releasing the source connection in response to receiving a PC5 unicast link release indication; ignoring the PC5 unicast link release indication; detecting whether a radio link failure (RLF) occurs between the UE and the relay node; releasing the source connection in response to detecting the RLF of the side link between the UE and the relay node; prohibiting the release of the source connection in response to detecting the RLF of the side link between the UE and the relay node; prohibiting the detection of the RLF of the side link between the UE and the relay node; or releasing the source connection in response to receiving an RRC reconfiguration message from the target cell.

[0135] In some embodiments of the present disclosure, the PC5 unicast link release indication may be indicated by an upper layer of the UE or received from a relay node.

[0136] In some embodiments of the present disclosure, prohibiting detection of RLF may include at least one of: prohibiting performance of radio link monitoring; or prohibiting declaration of RLF in response to expiration of a timer for sidelink RRC reconfiguration (e.g., T400 as specified in the 3GPP specification).

[0137] In some embodiments of the present disclosure, the notification message may be received in response to one of the following conditions: RLF between the relay node and the BS; reception of an RRC reconfiguration message containing a configuration with synchronization at the relay node; cell reselection at the relay node; RRC connection establishment failure or RRC recovery failure at the relay node; initiation of a reconstruction process at the relay node; a successful reconstruction process at the relay node; a failed reconstruction process at the relay node; and successful switching of the relay node.

[0138] In some embodiments of the present disclosure, releasing the source connection may include releasing the PC5 RRC connection between the UE and the relay node.

[0139] In some embodiments of the present disclosure, the UE may perform at least one of the following: fall back to the source connection in response to the expiration of the timer for the path switch; restore the UE configuration used in the source connection; and transmit an indication to the relay node indicating the fallback of the UE. The indication may be transmitted to the relay node via the RRC layer or the SRAP layer.

[0140] In some embodiments of the present disclosure, the UE may transmit capability information indicating whether the UE supports DAPS path switching. The capability information may indicate at least one of the following: whether the UE supports path switching from an indirect path to a direct path; or whether the UE supports path switching from an indirect path to another indirect path.

[0141] Those skilled in the art will appreciate that the sequence of operations in exemplary process 700 may be changed, and some of the operations in exemplary process 700 may be eliminated or modified without departing from the spirit and scope of the present disclosure.

[0142] Figure 8 800 for wireless communication according to some embodiments of the present disclosure. Figure 8 In some examples, the process may be performed by a relay node (eg, a relay UE).

[0143] refer to Figure 8 In operation 811, the relay node may establish a PC5 connection for a link between the UE and the relay node, wherein the UE communicates with the BS via the relay node. In operation 813, the relay node may receive information associated with a DAPS path switch for the UE from the BS or the UE.

[0144] In some embodiments of the present disclosure, information may be received from a BS and may indicate at least one of: whether a bearer associated with a relay node and a UE should be suspended or continued; or a DAPS path switch is performed at the UE. In some embodiments, to indicate whether a bearer associated with a relay node and a UE should be suspended or continued, the information may include an indication indicating whether the bearer is associated with a DAPS path switch.

[0145] In some embodiments of the present disclosure, in response to receiving information, the relay node may perform at least one of the following: continuing communications associated with the bearer when the information indicates that the bearer is associated with a DAPS path switch; or releasing data associated with the bearer when the information indicates that the bearer is not associated with a DAPS path switch.

[0146] In some embodiments of the present disclosure, after receiving the information, the relay node may transmit a PC5 unicast link release indication (e.g., a PC5-S release message or a PC5-S message) to the UE in response to one of the following conditions: RLF between the relay node and the BS; reception of an RRC reconfiguration message containing a synchronization configuration at the relay node; cell reselection at the relay node; RRC connection establishment failure or RRC recovery failure at the relay node; initiation of a reconstruction process at the relay node; a successful reconstruction process at the relay node; a failed reconstruction process at the relay node; and successful switching of the relay node.

[0147] In some embodiments of the present disclosure, information may be received from a UE and may indicate a fallback of a DAPS path switch. The information may be received from the UE via an RRC layer or an SRAP layer.

[0148] In some embodiments of the present disclosure, the information may be received from the BS and may indicate the fallback of the DAPS path switch and the ID of the UE. The information may be received from the BS via an RRC message.

[0149] In some embodiments of the present disclosure, the relay node may restore the bearers not associated with the DAPS path switch back to the source configuration in response to receiving the information.

[0150] Those skilled in the art will appreciate that the sequence of operations in exemplary process 800 may be changed, and some of the operations in exemplary process 800 may be eliminated or modified without departing from the spirit and scope of the present disclosure.

[0151] Fig. 9 Flowchart illustrating an exemplary process 900 for wireless communication according to some embodiments of the present disclosure. Fig. 9 In some examples, the process may be performed by a BS.

[0152] refer to Fig. 9 In operation 911, the BS may transmit an RRC reconfiguration message for DAPS path switching to the UE via the relay node. In operation 913, the BS may transmit information associated with DAPS path switching to the relay node.

[0153] In some embodiments of the present disclosure, the BS may receive capability information indicating whether the UE supports DAPS path switching. The capability information may indicate at least one of the following: whether the UE supports path switching from an indirect path to a direct path; or whether the UE supports path switching from an indirect path to another indirect path.

[0154] In some embodiments of the present disclosure, the information may indicate at least one of: whether a bearer associated with the relay node and the UE should be suspended or continued; or a DAPS path switch is performed at the UE. In some embodiments, to indicate whether a bearer associated with the relay node and the UE should be suspended or continued, the information may include an indication indicating whether the bearer is associated with a DAPS path switch.

[0155] In some embodiments of the present disclosure, the BS may receive a failure indication of the DAPS path switch from the UE. Information may be transmitted in response to receiving the failure indication and may indicate the fallback of the DAPS path switch and the ID of the UE. The information may be transmitted via an RRC message.

[0156] Those skilled in the art will appreciate that the sequence of operations in exemplary process 900 may be changed, and some of the operations in exemplary process 900 may be eliminated or modified without departing from the spirit and scope of the present disclosure.

[0157] Fig.10 A block diagram illustrating an exemplary apparatus 1000 according to some embodiments of the present disclosure.

[0158] like Fig.10 , the apparatus 1000 may include at least one processor 1006 and at least one transceiver 1002 coupled to the processor 1006. The apparatus 1000 may be a BS, a relay node, or a UE.

[0159] Although in this figure, elements such as at least one transceiver 1002 and processor 1006 are described in singular form, plural form is contemplated unless limitation to the singular form is explicitly stated. In some embodiments of the present application, transceiver 1002 may be divided into two devices, such as a receiving circuit system and a transmitting circuit system. In some embodiments of the present application, device 1000 may further include an input device, a memory, and / or other components.

[0160] In some embodiments of the present application, the device 1000 may be a UE. The transceiver 1002 and the processor 1006 may interact with each other to perform Figures 1 to 9 In some embodiments of the present application, the device 1000 may be a relay node. The transceiver 1002 and the processor 1006 may interact with each other to perform Figures 1 to 9 In some embodiments of the present application, the device 1000 may be a BS. The transceiver 1002 and the processor 1006 may interact with each other to perform Figures 1 to 9 The operation of BS is described in .

[0161] In some embodiments of the present application, the apparatus 1000 may further include at least one non-transitory computer-readable medium.

[0162] For example, in some embodiments of the present disclosure, the non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 1006 to implement the method for the UE as described above. For example, when executed, the computer-executable instructions cause the processor 1006 to interact with the transceiver 1002 to perform Figures 1 to 9 The operations of the UE are described in .

[0163] In some embodiments of the present disclosure, the non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 1006 to implement the method for the relay node as described above. For example, when executed, the computer-executable instructions cause the processor 1006 to interact with the transceiver 1002 to perform Figures 1 to 9 The operations of relay nodes are described in .

[0164] In some embodiments of the present disclosure, the non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause the processor 1006 to implement the method for the BS as described above. For example, when executed, the computer-executable instructions cause the processor 1006 to interact with the transceiver 1002 to perform Figures 1 to 9 The operation of BS is described in .

[0165] Those of ordinary skill in the art will appreciate that the operations or 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. In addition, in some aspects, the operations or 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.

[0166] Although the present disclosure has been described with its specific embodiments, it is apparent that many alternatives, modifications and variations may be apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added or replaced in other embodiments. In addition, all elements of each figure are not necessarily required for the operation of the disclosed embodiments. For example, it will enable a person of ordinary skill in the art of the disclosed embodiments 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 as described herein are intended to be illustrative, not restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0167] In this document, the term "switching" and "path switching" are used interchangeably. The term "includes, including" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment containing a series of elements not only includes those elements, but also may include other elements that are not explicitly listed or inherent to such processes, methods, articles or equipment. In the absence of more constraints, the element starting with "a, an" or the like does not exclude the presence of additional identical elements in the process, method, article or equipment containing the element. In addition, the term "another" is defined as at least the second or more. The term "having" and the like as used herein are defined as "including". For example, the expression of "A and / or B" or "at least one of A and B" may include any and all combinations of words listed together with the expression. For example, the expression "A and / or B" or "at least one of A and B" may include A, B or both A and B. The wording "first", "second" or the like is only used to clearly illustrate the embodiments of the present application, and is not used to limit the substantive content of the present application.

Claims

1. A user equipment UE, comprising: Transceiver; and a processor coupled to the transceiver, wherein the processor is configured to: communicating with a base station BS via a relay node; receiving, from the BS via the relay node, a radio resource control (RRC) reconfiguration message for a dual active protocol stack (DAPS) path switch from a source connection to a target connection; and A timer for path switching is started in response to receiving the RRC reconfiguration message.

2. The UE of claim 1, wherein the processor is further configured to perform at least one of the following: releasing the source connection in response to receiving a notification message from the relay node while the timer for path switching is running; releasing the source connection in response to detecting a radio link failure RLF of a side link between the UE and the relay node while the timer for path switching is running; releasing the source connection in response to receiving a PC5 unicast link release indication while the timer for path switching is running; suspending the source connection in response to receiving a notification message from the relay node while the timer for path switching is running; or In response to a connection between the relay node and the BS becoming available, the suspended source connection is resumed.

3. The UE of claim 1, wherein the processor is further configured to: stopping the timer for path switching in response to successful completion of random access on the target cell of the DAPS path switching or successful transmission of an RRC reconfiguration complete message; and After stopping the timer for path switching, performing at least one of the following: releasing the source connection in response to receiving a notification message from the relay node; Ignore a notification message received from the relay node; Releasing the source connection in response to receiving a PC5 unicast link release indication; Ignore PC5 unicast link release indication; Detecting whether a radio link failure RLF occurs between the UE and the relay node; releasing the source connection in response to detecting a RLF of a side link between the UE and the relay node; prohibiting releasing the source connection in response to detecting RLF of a side link between the UE and the relay node; prohibiting detection of RLF of a side link between the UE and the relay node; or The source connection is released in response to receiving an RRC reconfiguration message from the target cell.

4. The UE according to claim 2 or claim 3, wherein the PC5 unicast link release indication is indicated by an upper layer of the UE or received from the relay node.

5. The UE of claim 3, wherein inhibiting the detection of the RLF comprises at least one of: prohibiting the performance of radio link monitoring; or Declaring RLF in response to expiration of a timer for sidelink RRC reconfiguration is prohibited.

6. The UE according to claim 2 or 3, wherein the notification message is received in response to one of the following conditions: RLF between the relay node and the BS; reception at the relay node of an RRC reconfiguration message including a configuration with synchronization; cell reselection at the relay node; RRC connection establishment failure or RRC recovery failure at the relay node; initiation of a reestablishment process at the relay node; A successful reestablishment process at the relay node; A failure re-establishment process at the relay node; and Successful handover of the relay node.

7. The UE according to claim 2 or 3, wherein releasing the source connection comprises releasing a PC5 RRC connection between the UE and the relay node.

8. The UE of claim 1, wherein the processor is configured to perform at least one of the following: falling back to the source connection in response to expiration of the timer for path switching; reverting back to the UE configuration used in the source connection; and An indication is transmitted to the relay node indicating the backoff for the UE.

9. The UE according to claim 8, wherein the indication is transmitted to the relay node via an RRC layer or a Sidelink Relay Adaptation Protocol (SRAP) layer.

10. The UE of claim 1, wherein the processor is further configured to transmit capability information indicating whether the UE supports DAPS path switching.

11. The UE according to claim 10, wherein the capability information indicates at least one of the following: whether the UE supports path switching from an indirect path to a direct path; or Whether the UE supports path switching from an indirect path to another indirect path.

12. A relay node, comprising: Transceiver; and a processor coupled to the transceiver, wherein the processor is configured to: establishing a PC5 connection for a link between a user equipment UE and the relay node, wherein the UE communicates with a base station BS via the relay node; and Information associated with a dual active protocol stack (DAPS) path switch for the UE is received from the BS or the UE.

13. The relay node of claim 12, wherein the information is received from the BS and indicates at least one of: whether bearers associated with the relay node and the UE should be suspended or continued; or A DAPS path switch is performed at the UE.

14. A base station BS, comprising: Transceiver; and a processor coupled to the transceiver, wherein the processor is configured to: transmitting a radio resource control (RRC) reconfiguration message for dual active protocol stack (DAPS) path switching to a user equipment (UE) via a relay node; and Information associated with the DAPS path switch is transmitted to the relay node.

15. The BS of claim 20, wherein the information indicates at least one of: whether bearers associated with the relay node and the UE should be suspended or continued; or A DAPS path switch is performed at the UE.

Images