Method and apparatus for multi-path conditions

Abstract

Methods and apparatus for multi-path conditions. A user equipment (UE) may include a processor configured to access a serving base station (BS) via a first path; and a transceiver coupled to the processor and configured to receive a reconfiguration message from the serving BS indicating that the UE adds a second path; the processor is further configured to, in response to receiving the reconfiguration message, execute a path addition program to add the second path and initiate a timer for the path addition program.

Description

Technical Field

[0001] Embodiments of the present application relate generally to wireless communication techniques, and more particularly to methods and apparatus for multipath situations. Background Art

[0002] Vehicle-to-everything (V2X) has been introduced into 5G wireless communication technology. In terms of the channel structure of V2X communication, the direct link between two user equipments (UEs) is called a side link. Side link is a long-term evolution (LTE) feature introduced in 3GPP Release 12, and enables direct communication between near-end UEs without the data passing through the BS or core network.

[0003] In the 3rd Generation Partnership Project (3GPP), the deployment of relay nodes (RN) in wireless communication systems is promoted. One purpose of deploying RN is to enhance the coverage area of ​​BS by improving the throughput of user equipment (UE) located within the coverage area or far away from the BS, which may result in relatively low signal quality. In some cases, RN can also be named as relay UE.

[0004] In a wireless communication system, a UE may operate in a multipath situation. The multipath may also be named as "multiple paths" or similar. In some examples, the multipath situation may include a direct path and an indirect path via a relay UE. However, details on how to add paths to support the multipath situation and how to perform a cell change in the multipath situation have not been specifically discussed. Summary of the invention

[0005] Some embodiments of the present application at least provide a technical solution for multipath situations.

[0006] According to some embodiments of the present application, a UE may include: a processor configured to access a serving base station (BS) via a first path; and a transceiver coupled to the processor and configured to receive a reconfiguration message from the serving BS instructing the UE to add a second path; the processor is further configured to execute a path addition procedure to add the second path and start a timer for the path addition procedure in response to receiving the reconfiguration message.

[0007] In some embodiments of the present application, the first path is an indirect path associated with a relay UE between the UE and the serving BS, and the second path is a direct path between the UE and the serving BS.

[0008] In some embodiments of the present application, the transceiver is further configured to receive a notification message or a PC5 signaling (PC5-S) release indication from the relay UE, or the processor is configured to detect a radio link failure (RLF) on the PC5 link between the UE and the relay UE when the UE is executing the path addition procedure.

[0009] In some embodiments of the present application, the processor is further configured to continue executing the path adding procedure in response to receiving the notification message or the PC5-S release indication or in response to detecting the RLF.

[0010] In some embodiments of the present application, in response to receiving the notification message from the relay UE, the transceiver is further configured to perform at least one of the following: suspend uplink (UL) transmission on the end-to-end link between the UE and the serving BS; or continue to receive downlink (DL) transmission from the relay UE.

[0011] In some embodiments of the present application, in response to receiving the PC5-S release indication from the relay UE, the processor is further configured to perform at least one of the following: releasing the end-to-end link between the UE and the serving BS; or releasing the PC5 link between the UE and the relay UE.

[0012] In some embodiments of the present application, in response to detecting the RLF on the PC5 link, the processor is further configured to perform at least one of the following: suspending the end-to-end link between the UE and the serving BS; or suspending the PC5 link between the UE and the relay UE.

[0013] In some embodiments of the present application, the processor is further configured to perform at least one of: releasing the end-to-end link between the UE and the serving BS; or releasing the PC5 link between the UE and the relay UE.

[0014] In some embodiments of the present application, in response to the UE successfully adding the direct path, the transceiver is further configured to transmit fault-related information to the serving BS via the direct path, and wherein the fault-related information indicates one of the following: receiving the notification message from the relay UE; receiving the PC5-S release indication from the relay UE; and detecting the RLF on the PC5 link.

[0015] In some embodiments of the present application, in response to the UE failing to add the direct path, the processor is further configured to initiate a recovery procedure.

[0016] In some embodiments of the present application, the processor is further configured to stop executing the path adding procedure and start a recovery procedure in response to receiving the notification message or the PC5-S release indication or in response to detecting the RLF.

[0017] In some embodiments of the present application, the first path is a direct path between the UE and the serving BS, and the second path is an indirect path associated with a relay UE between the UE and the serving BS.

[0018] In some embodiments of the present application, the processor is further configured to: detect a RLF on the direct path between the UE and the serving BS when the UE is performing the path adding procedure; and continue to perform the path adding procedure in response to detecting the RLF.

[0019] In some embodiments of the present application, the processor is further configured to: suspend the direct link between the UE and the serving BS; or release the direct link between the UE and the serving BS.

[0020] In some embodiments of the present application, in response to the UE successfully adding the direct path, the transceiver is further configured to transmit failure-related information to the serving BS via the direct path, and wherein the failure-related information indicates detection of the RLF on the direct path.

[0021] In some embodiments of the present application, in response to the UE failing to add the indirect path, the processor is further configured to initiate a recovery procedure.

[0022] In some embodiments of the present application, the processor is further configured to: detect a RLF on the direct path between the UE and the serving BS when the UE is executing the path adding procedure; and in response to detecting the RLF, stop executing the path adding procedure and start a recovery procedure.

[0023] In some embodiments of the present application, the processor is configured to: stop the timer in response to the UE successfully completing the path adding procedure; or declare failure of the path adding procedure once the timer for the path adding procedure expires.

[0024] In some embodiments of the present application, the UE is configured with the first path and the second path after stopping the timer, and the transceiver is further configured to receive an indication from the relay UE or from the BS, and wherein the indication indicates at least one of the following: the relay UE switches to a target cell within the serving BS; or the UE suspends the first path or the second path, and the second path is an indirect path between the serving BS and the UE.

[0025] In some embodiments of the present application, the processor is further configured to suspend the first path or the second path as an indirect path in response to receiving the indication from the relay UE or from the BS.

[0026] According to some other embodiments of the present application, a BS may include: a processor configured to communicate with a UE via a first path; a transceiver coupled to the processor and configured to: transmit a reconfiguration message to the UE indicating that the UE adds a second path; and receive failure-related information associated with the first path from the UE.

[0027] In some embodiments of the present application, the first path is an indirect path associated with a relay UE between the UE and the BS, and the second path is a direct path between the UE and the BS, and the fault-related information indicates one of the following: receiving a notification message from the relay UE; receiving a PC5-S release indication from the relay UE; and detecting an RLF on the PC5 link between the UE and the relay UE.

[0028] In some embodiments of the present application, the first path is a direct path between the UE and the BS, and the second path is an indirect path associated with a relay UE between the UE and the BS, and the fault-related information indicates that an RLF on the direct path between the UE and the BS is detected.

[0029] According to some embodiments of the present application, a method performed by a UE may include: accessing a serving BS via a first path; receiving a reconfiguration message from the serving BS instructing the UE to add a second path; and performing a path addition procedure to add the second path and starting a timer for the path addition procedure in response to receiving the reconfiguration message.

[0030] According to some embodiments of the present application, a method performed by a BS may include: communicating with a UE via a first path; transmitting a reconfiguration message to the UE instructing the UE to add a second path; and receiving failure-related information associated with the first path from the UE.

[0031] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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.

[0033] Figure 1 A schematic diagram illustrating a wireless communication system 100 according to some embodiments of the present application.

[0034] Figure 2 An exemplary flow chart illustrating a sidelink RRC reconfiguration procedure according to some embodiments of the present application.

[0035] Figure 3 A schematic diagram illustrating a wireless communication system 300 according to some embodiments of the present application.

[0036] Figure 4 A schematic diagram illustrating a wireless communication system 400 according to some embodiments of the present application.

[0037] Figures 5 to 9 An exemplary flow chart illustrating path addition according to some embodiments of the present application.

[0038] Fig.10 and 11 An exemplary flow chart illustrating a cell change according to some embodiments of the present application.

[0039] Fig.12 A flow chart illustrating an exemplary method for path addition according to some embodiments of the present application.

[0040] Fig.13 A flow chart illustrating another exemplary method for path addition according to some embodiments of the present application.

[0041] Fig.14 A simplified block diagram illustrating an apparatus 1400 for multipath situations according to some embodiments of the present application. DETAILED DESCRIPTION

[0042] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present application, and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions can be implemented by different embodiments intended to be included in the spirit and scope of the present application.

[0043] Reference will now be made in detail to some embodiments of the present application, 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 considered that, with the development of network architectures and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and in addition, the terms cited in the present application may be changed, which should not affect the principles of the present application.

[0044] Figure 1 A schematic diagram illustrating a wireless communication system 100 according to some embodiments of the present application.

[0045] As in 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 this application, 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.

[0046] NR sidelink communication may refer to AS functionality that enables at least V2X communication between neighboring UEs as defined in 3GPP specification TS23.287 using NR technology but without traversing any network nodes. V2X sidelink communication may refer to AS functionality that enables V2X communication between neighboring UEs as defined in 3GPP specification TS23.285 using 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 employing other wireless communication technologies.

[0047] 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 .

[0048] UE and BS may support communication based on, for example, 3G, long term evolution (LTE), LTE-Advanced (LTE-A), new radio (NR), or other suitable protocols. In some embodiments of the present application, 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. UE 101 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 application may change, but should not affect or limit the principles and spirit of the present application.

[0049] exist Figure 1 In the example of, BS102 and BS103 may be included in a next generation radio access network (NG-RAN). In an embodiment of the present application, BS102 may be a gNB, and BS103 may be an ng-eNB.

[0050] UE 101A and UE 101B may be within the NG-RAN 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 outside the NG-RAN coverage. 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. 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, e.g., via a PC5 interface as specified in a 3GPP standard document, respectively.

[0051] Support for V2X services via the PC5 interface may be provided, for example, through NR sidelink communication and / or V2X sidelink communication. NR sidelink communication may support one of the following three types of transmission models for a pair of source layer 2ID and destination layer 2ID: unicast transmission, multicast transmission, and broadcast transmission. When the UE is inside the NG-RAN coverage and when the UE is outside the NG-RAN coverage, sidelink communication transmission and reception through the PC5 interface are supported. For example, UE101A within the coverage of BS102 may perform sidelink transmission and reception (e.g., sidelink unicast transmission, sidelink multicast transmission, or sidelink broadcast transmission) through the PC5 interface. UE 101C outside the coverage of both BS102 and BS103 may also perform sidelink transmission and reception through the PC5 interface.

[0052] 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 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.

[0053] 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 pre-configured 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 in the resource pool based on, for example, measurement results and sensing results.

[0054] Figure 2 An exemplary flow chart illustrating a sidelink RRC reconfiguration procedure according to some embodiments of the present application. Figure 2 As shown in FIG. 2 , in operation 201, UE (a) (e.g., as in Figure 1 101C) sends a RRCReconfigurationSidelink message to UE(b) (e.g., as in Figure 1 UE 101A) described and shown in FIG. 1 initiates a sidelink RRC reconfiguration procedure.

[0055] If the sidelink RRC reconfiguration procedure is successfully completed, then in operation 202, UE (b) may transmit an "RRC reconfiguration complete sidelink message" to UE (a), such as an RRCReconfigurationCompleteSidelink message as specified in the 3GPP standard document. Alternatively, if the sidelink RRC reconfiguration procedure is not successfully completed, then in operation 202, UE (b) may transmit an "RRC reconfiguration failure sidelink message" to UE (a), such as an RRCReconfigurationFailureSidelink message as specified in the 3GPP standard document.

[0056] The purpose of the sidelink RRC reconfiguration procedure is to modify the PC5 RRC connection, for example, to establish, modify or release sidelink data radio bearers (DRBs), to configure NR sidelink measurements and reporting, and to configure sidelink channel state information (CSI) reference signal resources.

[0057] In the following cases, the UE (for example, Figure 2 The UE (a) described and shown in FIG. 1 may initiate a sidelink RRC reconfiguration procedure and perform operations on the corresponding PC5 RRC connection:

[0058] - Release the connection with the peer UE (e.g., as in Figure 2 A sidelink DRB associated with the UE (b)) described and shown in FIG.

[0059] - Establishing a sidelink DRB associated with a peer UE;

[0060] - Modify the parameters contained in the Sidelink Radio Bearer (SLRB)-Config of the sidelink DRB associated with the peer UE;

[0061] - Configuration information of peer UEs to perform NR sidelink measurements and reporting; and

[0062] - Configuration information of sidelink CSI reference signal resources.

[0063] In some cases, Uu coverage reachability is necessary for a UE to reach a server in a public data network (PDN) network or a corresponding UE outside a neighboring area. In order to achieve UE-to-network coverage extension, UE-to-network relay can be introduced in a wireless communication system. Examples of UE-to-network relay can be referenced in Figure 3 .

[0064] Figure 3 A schematic diagram illustrating a wireless communication system 300 according to some embodiments of the present application.

[0065] As in Figure 3As shown in FIG. 3 , a wireless communication system 300 may include one BS (e.g., BS 302) and some UEs (e.g., UE 301A and UE 301B). UE 301B may be within the coverage of BS 302, and UE 301A may be out of coverage. Figure 3 A specific number of UEs and BSs are depicted in FIG. 3 , but it is contemplated that any number of UEs may be included in the wireless communication system 300 .

[0066] The wireless communication system 300 may support sidelink communication. For example, UE 301B may be in sidelink communication with UE 301A. Although UE 301A is outside the coverage of BS 302, UE 301A may access BS 202 via UE 301B. UE 301A and BS 302 may therefore establish a radio resource control (RRC) connection therebetween, and UE 301A may have RRC states, such as RRC_IDLE state, RRC_INACTIVE state, and RRC_CONNECTED state. In the context of the present application, a UE (e.g., UE 301B) acting as a relay between a UE and a BS may be referred to as a UE-to-network relay. It should be appreciated by those skilled in the art that although in Figure 3 A single relay node between UE 301A and BS 302 is depicted in FIG, but it is contemplated that any number of relay nodes may be included.

[0067] Figure 4 Schematic diagram of a wireless communication system 400 according to some embodiments of the present application. Figure 4 As described and shown in FIG. 4 , for illustrative purposes, a wireless communication system 400 includes at least two UEs (ie, UE 401 and relay UE 402) and at least one BS (eg, BS 403). Figure 4 A 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. Figure 4 , UE 401 may operate in a multipath situation, for example, UE 401 may communicate with BS 403 via a direct path (also referred to as a direct link) between UE 401 and BS 403 or via an indirect path (also referred to as an indirect link) between UE 401 and BS 403 through relay UE 402. The indirect link between UE 401 and BS 403 may include a PC5 link between UE 401 and relay UE 402 and a link between relay UE 402 and BS 403.

[0068] Figure 5 An exemplary flow chart illustrating path addition according to some embodiments of the present application. Figure 5The method described in the above may be performed by a UE (also referred to as a remote UE, such as Figure 4 UE 401 in the relay UE (eg, Figure 4 UE 402 in the UE) and BS (also referred to as the serving BS of the remote UE, e.g. Figure 4 Although the method is described at the system level, those skilled in the art should understand that the method implemented in the two network nodes can be implemented separately and can be incorporated into other devices with similar functions.

[0069] exist Figure 5 In an embodiment of the present invention, the remote UE may access the serving BS via a Uu link (eg, a direct path).

[0070] In operation 501, the remote UE may report a measurement result to the serving BS based on a configuration from the serving BS.

[0071] In operation 502, the serving BS may decide to add another indirect path based on the measurement result from the remote UE.

[0072] In operation 503, the BS may transmit an RRC reconfiguration message for path addition to the remote UE.

[0073] In operation 504, the remote UE establishes a PC5 connection with the relay UE indicated by the RRC reconfiguration message.

[0074] In operation 505, the serving BS may transmit an RRC reconfiguration message associated with the remote UE to the relay UE.

[0075] Once another indirect path is successfully added, in operation 506, the remote UE may transmit an RRC reconfiguration complete message to the serving BS.

[0076] In operation 507, the remote UE may transmit data to the serving BS or receive data from the BS (eg, via at least one of a direct link or a newly added indirect link).

[0077] According to some embodiments of the present application, a UE may access a BS via a first path (e.g., a direct path or an indirect path). The BS may configure the UE to add a second link (e.g., an indirect link or a direct link). In some cases, a first link failure may occur while the UE is performing a path addition procedure to add a second link. In such cases, it is necessary to address the behavior of the UE, such as how to handle the first link and how to handle the ongoing path addition procedure.

[0078] According to some embodiments of the present application, a UE may be configured with multiple paths (e.g., a direct path and an indirect path). In some cases, a relay UE in an indirect link may change its serving cell under the same BS. In such cases, the behavior of the BS, the behavior of the UE, and the behavior of the relay UE also need to be addressed.

[0079] In view of the above, the embodiments of the present application are intended to provide solutions for multipath situations. For example, the embodiments of the present application provide several solutions for adding paths and changing cells in multipath situations. Therefore, the embodiments of the present application can at least solve the above technical problems, thereby facilitating operations in multipath situations. More details about the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0080] Figure 6 Another exemplary flow chart illustrating path addition according to some embodiments of the present application. Figure 6 The method described in the above may be performed by a UE (also referred to as a remote UE, such as Figure 4 UE 401 in the relay UE (eg, Figure 4 UE 402 in the UE) and BS (also referred to as the serving BS of the remote UE, e.g. Figure 4 Although the method is described at the system level, those skilled in the art should understand that the method implemented in the two network nodes can be implemented separately and can be incorporated into other devices with similar functions.

[0081] refer to Figure 6 In operation 601, the UE may access the serving BS via a first path. Therefore, the BS may communicate with the UE via the first path. Figure 6 The first path in may be an indirect path associated with a relay UE between the UE and the serving BS. An indirect path may also be referred to as an indirect link, an end-to-end path, or an end-to-end link. An indirect link may include a PC5 link between the UE and the relay UE and a Uu link between the relay UE and the BS. The UE may remain in an RRC connected state.

[0082] In operation 602, the UE may transmit a measurement result to the serving BS based on a configuration from the serving BS.

[0083] In operation 603, based on the measurement result from the UE, the serving BS may determine to add a second path. The second path may be a direct path between the UE and the BS. The direct path may also be referred to as a direct link or a Uu link.

[0084] In operation 604, the serving BS may transmit a reconfiguration message instructing the UE to add the second path. For example, the reconfiguration message may be an RRC reconfiguration message as specified in the 3GPP standard document. In some embodiments, the reconfiguration message may include a target cell identification (ID).

[0085] In response to receiving the reconfiguration message, the UE may perform a path addition procedure to add a second path and start a timer for the path addition procedure in operation 605. For example, the timer may be T304 as specified in TS 38.331.

[0086] In operation 605, the UE may receive a notification message or a PC5-S release indication from the relay UE, or the UE may detect RLF on the PC5 link between the UE and the relay UE while the UE is performing a path addition procedure.

[0087] In operation 606, the UE may continue to perform the path addition procedure in response to receiving the notification message or the PC5-S release indication or in response to detecting the RLF.

[0088] In some embodiments, the UE may receive a notification message from the relay UE in operation 605. In an embodiment, the notification message may indicate at least one of the following:

[0089] (1) Relay Uu RLF between UE and network;

[0090] (2) Relay UE's cell reselection;

[0091] (3) Handover of relay UE;

[0092] (4) RRC connection failure of the relay UE;

[0093] (5) RRC connection rejection message received by the relay UE;

[0094] (6) Expiration of the timer for the RRC setup request at the relay UE;

[0095] (7) RRC recovery failure of the relay UE; or

[0096] (8) Any other information.

[0097] In such embodiments, in response to receiving the notification message from the relay UE, in operation 606 the UE may perform at least one of: suspending UL transmission on the end-to-end link between the UE and the serving BS; or continuing to receive DL transmission from the relay UE.

[0098] In some other embodiments of the present application, the UE may receive a PC5-S release indication from the relay UE in operation 605. For example, the UE may receive an indication indicating PC5-S release from an upper layer (eg, PC5-S layer).

[0099] In such embodiments, in response to receiving a PC5-S release indication from the relay UE, in operation 606, the UE may perform at least one of: releasing the end-to-end link between the UE and the serving BS; or releasing the PC5 link between the UE and the relay UE.

[0100] In some other embodiments of the present application, the UE may detect RLF on the PC5 link in operation 605. In such embodiments, in response to detecting the RLF on the PC5 link, the UE may perform at least one of the following in operation 606: suspending the end-to-end link between the UE and the serving BS; or suspending the PC5 link between the UE and the relay UE.

[0101] In some other embodiments of the present application, in response to receiving a notification message or a PC5-S release indication, or in response to detecting RLF in operation 605, in operation 606, the UE may perform at least one of the following: releasing the end-to-end link between the UE and the serving BS; or releasing the PC5 link between the UE and the relay UE.

[0102] In some cases, the UE may successfully add the direct path (e.g., the UE successfully completes the path addition procedure before the timer expires). Then, in operation 607', the UE may transmit the failure-related information to the serving BS via the direct path. In some embodiments, the failure-related information may be included in an RRC message (e.g., an RRC reconfiguration complete message as specified in a 3GPP standard document).

[0103] The failure-related information may include an indication indicating one of: receiving a notification message from the relay UE; receiving a PC5-S release indication from the relay UE; and detecting RLF on the PC5 link.

[0104] In an embodiment, in the case where the indication included in the fault related information indicates that a notification message is received from the relay UE, the fault related information may further include an indication type, for example, the indication type may indicate the content indicated by the notification message as stated above.

[0105] In an embodiment, the failure-related information may also include measurement results of candidate relays, so that the serving BS may reconfigure new candidate relays to the UE.

[0106] In some other cases, the UE may not be able to add the direct path (eg, a timer for the path addition procedure expires). Then, in operation 607 ″, the UE may initiate a recovery procedure, such as performing a reestablishment procedure.

[0107] Figure 7 Another exemplary flow chart illustrating path addition according to some embodiments of the present application. Figure 7 The method described in the above may be performed by a UE (also referred to as a remote UE, such as Figure 4 UE 401 in the relay UE (eg, Figure 4 UE 402 in the UE) and BS (also referred to as the serving BS of the remote UE, e.g. Figure 4 Although the method is described at the system level, those skilled in the art should understand that the method implemented in the two network nodes can be implemented separately and can be incorporated into other devices with similar functions.

[0108] refer to Figure 7 , operations 701 to 705 may be the same as operations 601 to 605, respectively. Figure 7 and Figure 6 The difference between them is operation 706 .

[0109] Specifically, in operation 706, the UE may stop performing the path adding procedure and start the recovery procedure (eg, perform the reestablishment procedure) in response to receiving the notification message or the PC5-S release indication or in response to detecting the RLF.

[0110] exist Figure 7 In an embodiment, the first path (eg, an indirect path) may be the primary path.

[0111] Figure 8 Yet another exemplary flow chart illustrating path addition according to some embodiments of the present application. Figure 8 The method described in the above may be performed by a UE (also referred to as a remote UE, such as Figure 4 UE 401 in the relay UE (eg, Figure 4 UE 402 in the UE) and BS (also referred to as the serving BS of the remote UE, e.g. Figure 4 Although the method is described at the system level, those skilled in the art should understand that the method implemented in the two network nodes can be implemented separately and can be incorporated into other devices with similar functions.

[0112] refer to Figure 8In operation 801, the UE may access the serving BS via a first path. Therefore, the BS may communicate with the UE via the first path. The first path may be a direct path between the UE and the BS. The direct path may also be referred to as a direct link or a Uu link. The UE may remain in an RRC connected state.

[0113] In operation 802, the UE may transmit a measurement result to the serving BS based on a configuration from the serving BS.

[0114] In operation 803, based on the measurement result from the UE, the serving BS may determine to add a second path. Figure 8 The second path in may be an indirect path associated with a relay UE between the UE and the serving BS. An indirect path may also be referred to as an indirect link, an end-to-end path, or an end-to-end link. An indirect link may include a PC5 link between the UE and the relay UE and a Uu link between the relay UE and the BS.

[0115] In operation 804, the serving BS may transmit a reconfiguration message instructing the UE to add the second path. For example, the reconfiguration message may be an RRC reconfiguration message as specified in the 3GPP standard document. In some embodiments, the reconfiguration message may include an ID of the relay UE.

[0116] In response to receiving the reconfiguration message, the UE may perform a path addition procedure to add a second path and start a timer for the path addition procedure in operation 805. For example, the timer may be T420 as specified in TS 38.331.

[0117] In operation 805, while the UE is performing a path adding procedure, the UE may detect a RLF on a direct path between the UE and a serving BS.

[0118] In operation 806, the UE may continue to perform the path addition procedure in response to detecting the RLF. In some embodiments of the present application, the UE may suspend the direct link between the UE and the serving BS in operation 806. Alternatively, in operation 806, the UE may release the direct link between the UE and the serving BS.

[0119] In some cases, the UE may successfully add the indirect path (e.g., the UE successfully completes the path addition procedure before the timer expires). Then, in operation 807', the UE may transmit the fault-related information to the serving BS via the indirect path. In some embodiments, the fault-related information may be included in an RRC message (e.g., an RRC reconfiguration complete message as specified in a 3GPP standard document). For example, the fault-related information may indicate that an RLF on the direct path is detected.

[0120] In some other cases, the UE may not be able to add the direct path (eg, a timer for the path addition procedure expires). Then, in operation 807 ″, the UE may initiate a recovery procedure, such as performing a reestablishment procedure.

[0121] Fig. 9 Yet another exemplary flow chart illustrating path addition according to some embodiments of the present application. Fig. 9 The method described in the above may be performed by a UE (also referred to as a remote UE, such as Figure 4 UE 401 in the relay UE (eg, Figure 4 UE 402 in the UE) and BS (also referred to as the serving BS of the remote UE, e.g. Figure 4 Although the method is described at the system level, those skilled in the art should understand that the method implemented in the two network nodes can be implemented separately and can be incorporated into other devices with similar functions.

[0122] refer to Fig. 9 , operations 901 to 905 may be the same as operations 801 to 805, respectively. Fig. 9 and Figure 8 The difference between them is operation 906.

[0123] Specifically, in operation 906, the UE may stop performing a path addition procedure and start a recovery procedure (eg, perform a reestablishment procedure) in response to detecting an RLF on a direct path between the UE and the serving BS.

[0124] exist Fig. 9 In an embodiment, the first path (eg, the direct path) may be the primary path.

[0125] Fig.10 An exemplary flow chart illustrating a cell change according to some embodiments of the present application. Fig.10 The method described in the above may be performed by a UE (also referred to as a remote UE, such as Figure 4 UE 401 in the relay UE (eg, Figure 4 UE 402 in the UE) and BS (also referred to as the serving BS of the remote UE, e.g. Figure 4 Although the method is described at the system level, those skilled in the art should understand that the method implemented in the two network nodes can be implemented separately and can be incorporated into other devices with similar functions.

[0126] refer to Fig.10In operation 1001, a UE may access a serving BS. The UE may remain in an RRC connected state. In operation 1001, the BS may transmit a reconfiguration message including a multipath configuration (e.g., a configuration of multiple paths) to the UE. For example, the multiple paths may include a direct path between the UE and the serving BS and an indirect path associated with a relay UE between the UE and the serving BS.

[0127] The direct path may also be referred to as a direct link or a Uu link.

[0128] The indirect path may also be referred to as an indirect link, an end-to-end path, or an end-to-end link. The indirect link may include a PC5 link between a UE and a relay UE and a Uu link between a relay UE and a BS.

[0129] In operation 1002, the UE may transmit a measurement result to the serving BS based on a configuration from the serving BS.

[0130] In operation 1003, based on the measurement result from the UE, the serving BS may determine to change the serving cell of the relay UE.

[0131] In operation 1004, the BS may transmit a reconfiguration message to the relay UE indicating a cell change (also referred to as a cell handover or handover) of the relay UE. For example, the reconfiguration message may be an RRC reconfiguration message as specified in a 3GPP standard document. In some embodiments, the reconfiguration message may include an ID of a target cell to which the relay UE may change (or handover). Alternatively or in addition, the reconfiguration message may also instruct the relay UE to transmit an indication to the UE, instructing the UE to suspend an indirect path between the serving BS and the UE (or instructing the UE to maintain multiple paths configured by the BS).

[0132] In response to receiving the reconfiguration message, the relay UE may perform a cell change procedure and transmit an indication to the UE in operation 1005, instructing the UE to suspend the indirect path between the serving BS and the UE (or instructing the UE to maintain multiple paths configured by the BS). In some embodiments, the indication may be transmitted in a notification message for the side link.

[0133] In response to receiving the indication, in operation 1006, the UE may perform at least one of: suspending the indirect path; or maintaining the multiple paths configured by the BS.

[0134] In case that the cell change procedure is successfully performed by the relay UE, in operation 1007 , the relay UE may transmit an indication to the UE instructing the UE to resume the suspended indirect path.

[0135] In operation 1008 , the UE may resume the suspended indirect path in response to receiving an indication instructing the UE to resume the suspended indirect path.

[0136] Fig.11 Another exemplary flow chart illustrating a cell change according to some embodiments of the present application. Fig.11 The method described in the above may be performed by a UE (also referred to as a remote UE, such as Figure 4 UE 401 in the relay UE (eg, Figure 4 UE 402 in the UE) and BS (also referred to as the serving BS of the remote UE, e.g. Figure 4 Although the method is described at the system level, those skilled in the art should understand that the method implemented in the two network nodes can be implemented separately and can be incorporated into other devices with similar functions.

[0137] refer to Fig.11 , operations 1101 to 1103 may be the same as operations 1001 to 1003, respectively.

[0138] In operation 1104, the BS may transmit a reconfiguration message indicating a cell change of the relay UE to the relay UE. For example, the reconfiguration message may be an RRC reconfiguration message as specified in the 3GPP standard document. In some embodiments, the reconfiguration message may include an ID of a target cell to which the relay UE may change (or switch).

[0139] In operation 1105, the BS may transmit an indication to the UE. The indication may indicate at least one of the following: the relay UE switches to a target cell within the serving BS (or the UE is about to perform a cell change to the target cell, or the UE is performing a cell change to the target cell); or the UE is about to suspend an indirect path between the serving BS and the UE (or the UE maintains multiple paths configured by the BS). In some embodiments, the indication may be transmitted to the UE in a reconfiguration message (e.g., an RRC reconfiguration message as specified in a 3GPP standard document).

[0140] In response to receiving the reconfiguration message, at operation 1106 , the relay UE may perform a cell change procedure.

[0141] In response to receiving the indication, in operation 1107, the UE may perform at least one of: suspending the indirect path; or maintaining the multiple paths configured by the BS.

[0142] In the case where the cell change procedure is successfully performed by the relay UE (i.e., a successful cell change), in operation 1108', the relay UE may transmit an indication to the UE indicating that the UE resumes the suspended indirect path (or indicating a successful cell change of the relay UE). Alternatively, in operation 1108", the BS may transmit an indication to the UE indicating that the UE resumes the suspended indirect path (or indicating a successful cell change of the relay UE).

[0143] In operation 1109 , the UE may resume the suspended indirect path in response to receiving an indication instructing the UE to resume the suspended indirect path from the relay UE or the BS.

[0144] Fig.12 A flow chart illustrating an exemplary method for path addition according to some embodiments of the present application. Fig.12 The method in may be performed by a UE (e.g., as in Figure 4 Implementation of the remote UE 401 shown in FIG.

[0145] exist Fig.12 In the exemplary method shown in , in operation 1201, the UE may access the serving BS via the first path. In operation 1203, the UE may receive a reconfiguration message from the serving BS instructing the UE to add a second path. In operation 1205, the UE may perform a path adding procedure to add the second path and start a timer for the path adding procedure in response to receiving the reconfiguration message.

[0146] According to some embodiments of the present application, the first path may be an indirect path associated with a relay UE between the UE and the serving BS, and the second path may be a direct path between the UE and the serving BS. Figure 6 and 7 .

[0147] In such embodiments, the UE may receive a notification message or a PC5-S release indication from the relay UE, or the UE may detect the RLF on the PC5 link between the UE and the relay UE while the UE is performing a path addition procedure.

[0148] In some embodiments of the present application, the UE continues to perform the path addition procedure in response to receiving a notification message or a PC5-S release indication or in response to detecting an RLF. Figure 6 .

[0149] In an embodiment, in response to receiving the notification message from the relay UE, the UE may perform at least one of: suspending UL transmission on the end-to-end link between the UE and the serving BS; or continuing to receive DL transmission from the relay UE.

[0150] In another embodiment, in response to receiving a PC5-S release indication from the relay UE, the UE may perform at least one of the following: releasing the end-to-end link between the UE and the serving BS; or releasing the PC5 link between the UE and the relay UE.

[0151] In yet another embodiment, in response to detecting the RLF on the PC5 link, the UE may perform at least one of: suspending the end-to-end link between the UE and the serving BS; or suspending the PC5 link between the UE and the relay UE.

[0152] In yet another embodiment, in response to receiving a notification message or a PC5-S release indication, or in response to detecting an RLF, the UE may perform at least one of the following: releasing the end-to-end link between the UE and the serving BS; or releasing the PC5 link between the UE and the relay UE.

[0153] In some cases, in response to the UE successfully adding the direct path, the UE may transmit failure-related information to the serving BS via the direct path. The failure-related information may indicate one of the following: receiving a notification message from the relay UE; receiving a PC5-S release indication from the relay UE; and detecting RLF on the PC5 link.

[0154] In some other cases, in response to the UE failing to add the direct path, the UE may initiate a recovery procedure.

[0155] In some other embodiments of the present application, the UE may stop executing the path addition procedure and start the recovery procedure in response to receiving a notification message or a PC5-S release indication or in response to detecting RLF. Figure 7 .

[0156] According to some embodiments of the present application, the first path is a direct path between the UE and the serving BS, and the second path is an indirect path associated with a relay UE between the UE and the serving BS. Figure 8 and 9 .

[0157] In some embodiments, while the UE is performing a path addition procedure, the UE may detect an RLF on a direct path between the UE and the serving BS. The UE may then continue to perform the path addition procedure in response to detecting the RLF. Figure 8 .

[0158] In an embodiment, in response to detecting the RLF, the UE may suspend the direct link between the UE and the serving BS; or release the direct link between the UE and the serving BS.

[0159] In some cases, in response to the UE successfully adding the indirect path, the UE may transmit failure-related information to the serving BS via the indirect path. The failure-related information may indicate that an RLF on the direct path is detected.

[0160] In some other cases, in response to the UE failing to add the indirect path, the UE may initiate a recovery procedure.

[0161] In some other embodiments, when the UE is performing a path addition procedure, the UE may detect an RLF on the direct path between the UE and the serving BS. Then, in response to detecting the RLF, the UE may stop performing the path addition procedure and initiate a recovery procedure. Fig. 9 .

[0162] In the above-mentioned embodiments, the UE may stop the timer in response to the UE successfully completing the path adding procedure; or declare the failure of the path adding procedure once the timer for the path adding procedure expires.

[0163] After stopping the timer, the UE is configured with the first path and the second path. In some cases, the UE may be connected to the relay UE (see Fig.10 ) or from BS (see Fig.11 ) receives an indication. The indication may indicate at least one of the following: the relay UE switches to a target cell within the serving BS; or the UE suspends the first path or the second path, where the second path is an indirect path between the serving BS and the UE.

[0164] Then, the UE may suspend the first path or the second path as an indirect path in response to receiving an indication from the relay UE or from the BS.

[0165] Fig.13 A flow chart illustrating another exemplary method for path addition according to some embodiments of the present application. Fig.13 The method in can be implemented by BS (e.g., Figure 4 The service shown in BS 403) is implemented.

[0166] exist Fig.13 In the exemplary method shown in , in operation 1301, the BS may communicate with a UE (e.g., a remote UE 401) via a first path. In operation 1303, the BS may transmit a reconfiguration message to the UE instructing the UE to add a second path. In operation 1305, the BS may receive failure-related information associated with the first path from the UE.

[0167] In some embodiments, the first path is an indirect path associated with a relay UE between the UE and the BS, and the second path is a direct path between the UE and B. In such embodiments, the failure-related information indicates one of: receiving a notification message from the relay UE; receiving a PC5-S release indication from the relay UE; and detecting RLF on the PC5 link between the UE and the relay UE. Examples may refer to Figure 6 .

[0168] In some other embodiments, the first path is a direct path between the UE and the BS, and the second path is an indirect path associated with a relay UE between the UE and the BS. In such embodiments, the fault-related information may indicate that an RLF is detected on the direct path between the UE and the BS. For example, see Figure 8 .

[0169] Fig.14A simplified block diagram illustrating an exemplary apparatus for multipath situations according to some embodiments of the present disclosure. Fig.14 , the apparatus 1400 may include at least one processor 1406 and at least one transceiver 1402 coupled to the processor 1406. The apparatus 1400 may be a UE or device having the same functionality, a relay UE or device having the same functionality, or a BS or device having the same functionality.

[0170] Although in this figure, elements such as at least one transceiver 1402 and processor 1406 are described in the singular, the plural is contemplated unless explicitly limited to the singular. In some embodiments of the present disclosure, the transceiver 1402 may be divided into two devices, such as a receive circuit system and a transmit circuit system. In some embodiments of the present disclosure, the device 1400 may further include an input device, a memory, and / or other components.

[0171] In some embodiments of the present disclosure, the device 1400 may be a UE (eg, a remote UE 401). The transceiver 1402 and the processor 1406 may interact with each other to perform Figures 1 to 13 In some embodiments of the present disclosure, the device 1400 may be a relay UE. The transceiver 1402 and the processor 1406 may interact with each other to perform Figures 1 to 13 In some embodiments of the present disclosure, the device 1400 may be a BS. The transceiver 1402 and the processor 1406 may interact with each other to perform Figures 1 to 13 The operations of BS are described in .

[0172] In some embodiments of the present disclosure, the device 1400 may further include at least one non-transitory computer-readable medium.

[0173] For example, in some embodiments of the present disclosure, the non-transitory computer-readable medium may store thereon computer-executable instructions to cause the processor 1406 to implement the method for the UE as described above. For example, when the computer-executable instructions are executed, the processor 1406 interacts with the transceiver 1402 to perform Figures 1 to 13 The operations of the UE are described in .

[0174] For example, in some embodiments of the present disclosure, a non-transitory computer-readable medium may store thereon computer-executable instructions to cause the processor 1406 to implement the method for relaying UE as described above. For example, when the computer-executable instructions are executed, the processor 1406 interacts with the transceiver 1402 to perform Figures 1 to 13 The operations of the relay UE are described in .

[0175] In some embodiments of the present disclosure, a non-transitory computer-readable medium may store thereon computer-executable instructions to cause the processor 1406 to implement the method for the BS as described above. For example, when the computer-executable instructions are executed, the processor 1406 interacts with the transceiver 1402 to perform Figures 1 to 13 The operation of BS is described in .

[0176] It will be understood by those skilled in the art that the operations or steps of the methods described in conjunction with the aspects disclosed herein may be directly embodied in hardware, a software module executed by a processor, or a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of 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 group of codes and / or instructions on a non-transitory computer-readable medium that can be incorporated into a computer program product.

[0177] 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, 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 set forth herein are intended to be illustrative, not restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0178] In this document, 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 contains the elements, but also may contain other elements that are not explicitly listed or inherent to the process, method, article or equipment. In the absence of more constraints, an 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 elements. 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 enumerated 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 disclosure, but is not used to limit the substantive content of the present disclosure.

Claims

1. A user equipment UE, comprising: A processor configured to access a serving base station BS via a first path; and a transceiver coupled to the processor and configured to receive a reconfiguration message from the serving BS instructing the UE to add a second path; Wherein the processor is further configured to, in response to receiving the reconfiguration message, execute a path adding procedure to add the second path and start a timer for the path adding procedure.

2. The UE of claim 1, wherein the first path is an indirect path associated with a relay UE between the UE and the serving BS, and the second path is a direct path between the UE and the serving BS.

3. The UE according to claim 2, wherein the transceiver is further configured to receive a notification message or a PC5 signaling PC5-S release indication from the relay UE, or the processor is configured to detect a radio link failure RLF on the PC5 link between the UE and the relay UE when the UE is executing the path addition procedure.

4. The UE of claim 3, wherein the processor is further configured to continue executing the path adding procedure in response to receiving the notification message or the PC5-S release indication or in response to detecting the RLF.

5. The UE of claim 4, wherein in response to receiving the notification message from the relay UE, the transceiver is further configured to perform at least one of the following: suspending uplink (UL) transmission on an end-to-end link between the UE and the serving BS; or Continue to receive downlink (DL) transmissions from the relay UE.

6. The UE of claim 4, wherein in response to receiving the PC5-S release indication from the relay UE, the processor is further configured to perform at least one of the following: releasing the end-to-end link between the UE and the serving BS; or The PC5 link between the UE and the relay UE is released.

7. The UE of claim 4, wherein in response to detecting the RLF on the PC5 link, the processor is further configured to perform at least one of the following: suspending the end-to-end link between the UE and the serving BS; or The PC5 link between the UE and the relay UE is suspended.

8. The UE of claim 4, wherein the processor is further configured to perform at least one of the following: releasing the end-to-end link between the UE and the serving BS; or The PC5 link between the UE and the relay UE is released.

9. The UE of claim 4, wherein in response to the UE successfully adding the direct path, the transceiver is further configured to transmit failure-related information to the serving BS via the direct path, and wherein the failure-related information indicates one of the following: receiving the notification message from the relay UE; Receive the PC5-S release indication from the relay UE; and The RLF on the PC5 link is detected.

10. The UE of claim 4, wherein in response to the UE failing to add the direct path, the processor is further configured to initiate a recovery procedure.

11. The UE of claim 4, the processor being further configured to stop executing the path adding procedure and start a recovery procedure in response to receiving the notification message or the PC5-S release indication or in response to detecting the RLF.

12. The UE of claim 1, wherein the first path is a direct path between the UE and the serving BS, and the second path is an indirect path associated with a relay UE between the UE and the serving BS.

13. The UE of claim 12, wherein the processor is further configured to: When the UE is performing the path adding procedure, detecting a radio link failure (RLF) on the direct path between the UE and the serving BS; and The path addition procedure is continued in response to detecting the RLF.

14. A base station BS, comprising: a processor configured to communicate with a user equipment UE via a first path; a transceiver coupled to the processor and configured to: transmitting a reconfiguration message to the UE instructing the UE to add a second path; and Failure-related information associated with the first path is received from the UE.

15. A method performed by a user equipment UE, comprising: Accessing a serving base station BS via a first path; receiving, from the serving BS, a reconfiguration message instructing the UE to add a second path; and In response to receiving the reconfiguration message, a path adding procedure is performed to add the second path and a timer for the path adding procedure is started.

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