Communication method and device and computer storage medium

Abstract

An example embodiment of the present disclosure relates to a method of communication. In one embodiment, a first network device receives a first message at the first network device, the first message explicitly or implicitly indicating a successful transmission of a path switching configuration to a first terminal device, a first terminal device is connected to a first network device via a relay path including a second terminal device and is switched to a target path between the first terminal device and the second network device. The first network device sends, to the second terminal device, one of a second message for reconfiguring the relay path or a third message for triggering the second terminal device to apply a previously received second message for reconfiguring the relay path.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to methods, devices, and computer storage media for path switching. Background Art

[0002] In a wireless communication network device, a terminal device can communicate with a network device via a direct path or an indirect path. Specifically, in the case of a direct path, the terminal device can communicate directly with the network device, and in the case of an indirect path, the terminal device can communicate with the network device via at least one relay terminal device. In addition, the location and communication conditions of the terminal device can change over time. In order to maintain continuous communication with the network, the terminal device can sometimes switch to a new path or connect to a new network device, that is, perform path switching.

[0003] Generally speaking, during path switching, in the case where the source path is an indirect path, the release of the source path should be performed after the successful transmission of the path switch command to the terminal device. However, in the case where the source network device and the target network device are deployed in different physical devices (also known as inter-gNB) and the source path is an indirect path, the source network device does not know whether the path switch command has been successfully sent, which may cause the source path to be released before the successful transmission of the path switch command, which is an undesirable result. Therefore, in the case of inter-gNB, further discussion is needed on how to control the release of the relay path during path switching. Summary of the invention

[0004] Generally speaking, embodiments of the present disclosure provide methods, devices, and computer storage media for path switching.

[0005] In a first aspect, a method performed by a first network device is provided. The method comprises: receiving a first message at the first network device, the first message explicitly or implicitly indicating successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to the first network device via a relay path including a second terminal device and being switched to a target path between the first terminal device and the second network device; and sending to the second terminal device one of the following: a second message for reconfiguring the relay path or a third message for triggering the second terminal device to apply a previously received second message for reconfiguring the relay path.

[0006] In a second aspect, a method performed by a second network device is provided. The method includes: receiving a fourth message at the second network device, the fourth message explicitly or implicitly indicating successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to the first network device via a relay path including the second terminal device and being switched to a target path between the first terminal device and the second network device; and sending a first message to the first network device, the first message explicitly or implicitly indicating successful transmission of the path switching configuration to the first terminal device.

[0007] In a third aspect, a method performed by a second terminal device is provided. The method includes: determining, at the second terminal device, a successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to a first network device via a relay path including the second terminal device and being switched to a target path between the first terminal device and the second network device; and performing one of the following: sending a first message to the first network device, the first message indicating the successful transmission of the path switching configuration to the first terminal device; or applying a previously received second message for reconfiguring the relay path.

[0008] In a fourth aspect, a method performed by a first terminal device is provided. The method comprises: detecting a failure of a PC5 path between the first terminal device and a second terminal device at the first terminal device and via a keep-alive process without receiving a path switching configuration from the second terminal device, the first terminal device being connected to a first network device via the second terminal device; and initiating a reconstruction process with the second terminal device.

[0009] In a fifth aspect, a method performed by a core network (CN) device is provided. The method includes: generating a first message at the CN device, the first message explicitly or implicitly indicating successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to a first network device via a relay path including a second terminal device and being switched to a target path between the first device and the second network device; and sending the first message to the first network device.

[0010] In a sixth aspect, a first network device is provided. The first network device comprises: a processing unit; and a memory, the memory being coupled to the processing unit and storing instructions thereon, the instructions causing the device to perform the method according to the first aspect when executed by the processing unit.

[0011] In a seventh aspect, a second network device is provided. The second network device comprises: a processing unit; and a memory, the memory being coupled to the processing unit and storing instructions thereon, the instructions causing the device to perform the method according to the second aspect when executed by the processing unit.

[0012] In an eighth aspect, a second terminal device is provided, comprising: a processing unit; and a memory, the memory being coupled to the processing unit and storing instructions thereon, the instructions causing the device to perform the method according to the third aspect when executed by the processing unit.

[0013] In a ninth aspect, a first terminal device is provided, comprising: a processing unit; and a memory, the memory being coupled to the processing unit and storing instructions thereon, the instructions causing the device to perform the method according to the fourth aspect when executed by the processing unit.

[0014] In a tenth aspect, a CN device is provided. The CN device comprises: a processing unit; and a memory, the memory being coupled to the processing unit and storing instructions thereon, the instructions causing the device to perform the method according to the fifth aspect when executed by the processing unit.

[0015] In an eleventh aspect, a computer readable medium is provided having instructions stored thereon, which when executed on at least one processor causes the at least one processor to perform the method according to any one of the first to fifth aspects.

[0016] Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent by describing some embodiments of the present disclosure in more detail in the accompanying drawings, in which:

[0018] Figure 1A A signaling diagram illustrating a procedure for intra-gNB path switching in some embodiments is shown;

[0019] Figure 1B A signaling diagram illustrating a procedure for inter-gNB path switching in some embodiments is shown;

[0020] Figure 1C Another signaling diagram illustrating a procedure for inter-gNB path switching in some embodiments is shown;

[0021] Figure 2A A block diagram illustrating a communication environment in which embodiments of the present disclosure may be implemented;

[0022] Figure 2B A signaling diagram illustrating a process for communication according to some embodiments of the present disclosure is shown;

[0023] Figure 2C Another block diagram illustrating a communication environment in which embodiments of the present disclosure may be implemented;

[0024] Figure 3A signaling diagram illustrating a process for communication according to some embodiments of the present disclosure is shown;

[0025] 4A to 4F A signaling diagram illustrating a process for communication according to some embodiments of the present disclosure is shown;

[0026] Figure 5A and Figure 5B A signaling diagram illustrating a process for communication according to some embodiments of the present disclosure is shown;

[0027] Figure 6 An example method of communication implemented at a first network device according to some embodiments of the present disclosure is shown;

[0028] Figure 7 An example method of communication implemented at a second network device according to some embodiments of the present disclosure is shown;

[0029] Figure 8 An example method of communication implemented at a second terminal device according to some embodiments of the present disclosure is shown;

[0030] Fig. 9 An example method of communication implemented at a first terminal device according to some embodiments of the present disclosure is shown;

[0031] Fig.10 An example method of communication implemented at a CN device according to some embodiments of the present disclosure is shown; and

[0032] Fig.11 is a simplified block diagram of a device suitable for implementing embodiments of the present disclosure.

[0033] Throughout the drawings, the same or similar reference numerals refer to the same or similar elements. DETAILED DESCRIPTION

[0034] The principle of the present disclosure will now be described with reference to some embodiments. It should be understood that these embodiments are described only for illustrative purposes, and help those skilled in the art to understand and implement the present disclosure, without implying any limitation to the scope of the present disclosure. The disclosure described herein can be implemented in various ways except the way described below.

[0035] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0036] As used herein, the term "terminal device" refers to any device with wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, user equipment (UE), personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs), portable computers, tablet computers, wearable devices, Internet of Things (IoT) devices, ultra-reliable and low-latency communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communications (MTC) devices, on-vehicle devices for V2X communications (where X represents pedestrians, vehicles, or infrastructure / network), devices for integrated access and backhaul (IAB), space-borne vehicles or air-borne vehicles in non-terrestrial networks (NTNs) including satellites and high-altitude platforms (HAPs) covering unmanned aerial vehicle systems (UAS), extended reality (XR) devices including different types of reality (such as augmented reality (AR), mixed reality (MR), and virtual reality (VR)), unmanned aerial vehicles (UAVs) commonly referred to as drones (which are aircraft without any human pilots), devices on high-speed trains (HSTs), or image capture devices (such as digital cameras), sensors, gaming devices, music storage and playback devices, or Internet devices that enable wireless or wired Internet access and browsing, etc. The "terminal device" may also have "multicast / broadcast" features to support public safety and mission-critical, V2X applications, transparent IPv4 / IPv6 multicast delivery, IPTV, Smart TV, radio services, software delivery over the air, group communications, and IoT applications. It may also incorporate one or more subscriber identity modules (SIMs), known as multi-SIMs. The term "terminal device" may be used interchangeably with UE, mobile station, user station, mobile terminal, user terminal, or wireless device.

[0037] The term "network equipment" refers to equipment that is capable of providing or hosting a cell or coverage area in which a terminal device can communicate. Examples of network equipment include, but are not limited to, Node B (NodeB or NB), evolved NodeB (eNode B or eNB), next generation NodeB (gNB), transmission reception point (TRP), remote radio unit (RRU), radio head (RH), remote radio head (RRH), IAB node, low power node (such as femto node, pico node), reconfigurable smart surface (RIS), etc.

[0038] The terminal device or network device may have artificial intelligence (AI) or machine learning capabilities. It usually includes a model that has been trained from a large amount of collected data for a specific function and can be used to predict some information.

[0039] The terminal device or network device can operate in several frequency ranges, such as FR1 (410MHz to 7125MHz), FR2 (24.25GHz to 71GHz), bands greater than 100GHz and terahertz (THz). It can also operate on licensed / unlicensed / shared spectrum. In the multi-radio dual connection (MR-DC) application scenario, the terminal device can have more than one connection with the network device. The terminal device or network device can operate in full-duplex, flexible duplex and cross-duplex modes.

[0040] The embodiments of the present disclosure may be executed in a test device (eg, a signal generator, a signal analyzer, a spectrum analyzer, a network analyzer, a test terminal device, a test network device, a channel emulator).

[0041] In some embodiments, the terminal device may be connected to a first network device and a second network device. One of the first network device and the second network device may be a primary node, and the other may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs). In some embodiments, the first network device may be a first RAT device, and the second network device may be a second RAT device. In some embodiments, the first RAT device is an eNB, and the second RAT device is a gNB. Information related to different RATs may be sent to the terminal device from at least one of the first network device or the second network device. In some embodiments, the first information may be sent from the first network device to the terminal device, and the second information may be sent directly or via the first network device from the second network device to the terminal device. In some embodiments, information related to the configuration of the terminal device configured by the second network device may be sent from the second network device via the first network device. Information related to the reconfiguration of the terminal device configured by the second network device may be sent directly or via the first network device from the second network device to the terminal device.

[0042] As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "including" and its variations should be understood as open terms meaning "including but not limited to". The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other definitions, both explicit and implicit, may be included below.

[0043] In some examples, values, processes, or devices are referred to as "best," "lowest," "highest," "minimum," "maximum," etc. It will be understood that such descriptions are intended to indicate that a selection may be made among a number of functional alternatives used, and that such a selection is not necessarily better, lesser, higher, or otherwise preferred over other selections.

[0044] In a wireless communication network, a terminal device may communicate with the network via a direct network connection or an indirect network connection. In addition, in the case of a path switch, the communication path of the terminal device may be switched from a source network device to a target network device. In some embodiments, the source network device and the target network device are located in the same physical device (referred to as intra-gNB). Alternatively, in other embodiments, the source network device and the target network device are located in different physical devices (referred to as inter-gNB).

[0045] In view of this, path switching can be associated with any of the following: indirect to direct (I2D) path switching for intra-gNB, indirect to indirect (I2I) path switching for intra-gNB, direct to direct (D2D) path switching for intra-gNB, direct to indirect (D2I) path switching for intra-gNB, I2D for inter-gNB, I2I for inter-gNB, D2D for inter-gNB, and D2I for inter-gNB.

[0046] As described above, generally speaking, during path switching, in the case where the source path is an indirect path, the release of the source path should be performed after the successful transmission of the path switching command to the terminal device.

[0047] Figure 1A A signaling diagram illustrating a process 100 for intra-gNB path switching in some embodiments is shown. Figure 1A As shown, the remote UE initially performs 105 data transmission with the gNB via the relay UE. Then, a Uu measurement configuration and measurement reporting process 110 is performed 110 to evaluate both the relay link measurement and the Uu link measurement. Specifically, when the configured measurement reporting criteria are met, the measurement results from the layer 2 (L2) user to the network (U2N) remote UE are reported. In some embodiments, the sidelink relay measurement report may include at least one of the following: a source L2 identification (ID) of the L2U2N relay UE, a serving cell ID (i.e., an NR cell global identifier NCGI or an NR cell identifier NCI), and a sidelink measurement quantity result. The sidelink measurement quantity may be a sidelink (SL)-reference signal received power (RSRP) of the serving L2U2N relay UE, and if the SL-RSRP is not available, the sidelink discovery (SD)-RSRP is used. By using the measurement results, the gNB decides 115 to switch the L2U2N remote UE to a direct Uu path.

[0048] Next, the gNB sends 120 a radio resource control (RRC) reconfiguration message to the L2U2N remote UE. After receiving the RRC reconfiguration message with the path switch configuration from the gNB, the L2U2N remote UE stops uplink (UP) and control plane (CP) transmission via the L2U2N relay UE. In response to the RRC reconfiguration message, the L2U2N remote UE synchronizes with the gNB and performs 125 a random access (RA) with the gNB.

[0049] Thereafter, the UE (i.e., the L2U2N remote UE in the previous step) sends 130 an RRC reconfiguration complete message to the gNB via the established direct path using the configuration provided in the RRC reconfiguration message. From this step, the UE (i.e., the L2U2N remote UE in the previous step) uses an RRC connection via a direct path to the gNB. The gNB sends 135 an RRC reconfiguration message to the L2U2N relay UE to reconfigure the connection between the L2U2N relay UE and the gNB.

[0050] In a particular embodiment, based on the gNB implementation, the RRC reconfiguration message to the L2U2N relay UE may be sent at any time after sending the 120RRC reconfiguration message (e.g., to release the Uu and PC5 relay RLC channel configuration for the relay and the bearer mapping configuration associated with the L2U2N remote UE).

[0051] The AS layer of the L2U2N relay UE or L2U2N remote UE may release 140 the PC5-RRC connection and instruct the upper layers to release the PC5 unicast link after receiving an RRCReconfiguration message from the gNB. The timing of performing the link release depends on the UE implementation. Next, the data path is switched from an indirect path to a direct path between the UE (i.e., the previous L2U2N remote UE) and the gNB. If the gNB configures Packet Data Convergence Protocol (PDCP) re-establishment or PDCP data resumption in the UL, the PDCP re-establishment or PDCP data resumption in the UL is performed 145 by the UE (i.e., the previous L2U2N remote UE) for lossless delivery during the path switch.

[0052] exist Figure 1A In the specific embodiment of , since the source gNB also acts as the target gNB, the source gNB can reconfigure the relay UE to appropriately release the PC5 relay RLC channel after receiving the RRC reconfiguration complete message from the remote UE, which implies the successful transmission of the path switch command. In this way, it is ensured that after the successful transmission of the path switch command, the PC5 relay RLC channel is released (or the PC5 link is released, initiated by the relay UE).

[0053] For the inter-gNB case, the remote UE will access the target gNB instead of the source gNB, and the release of the relay RLC channel / reconfiguration of the relay UE is controlled by the source gNB. Therefore, in the inter-gNB case and the source path is a relay path, the source network device does not know whether the path switch command has been successfully sent. Now refer to Figure 1B and Figure 1 C, which shows a signaling diagram illustrating process 150 and process 160 for inter-gNB path switching in some embodiments.

[0054] like Figure 1B and Figure 1C As shown, in the case of a path switch command transmission failure, an incorrect PC5 connection may be triggered. In other words, the PC5 relay RLC channel / PC5 ​​link may be released (e.g., initiated by the relay UE) before the successful transmission of the path switch command, which is an undesirable result. For example, without the successful transmission of the path switch command, the remote UE cannot trigger the establishment of a new connection with the target network device, but the source connection has been released, which means that the communication of the remote UE will be interrupted. In addition, since the source connection has been released, the source network device cannot retransmit the path switch command to the remote UE again, which causes the connection status information at the remote UE to be inconsistent with the connection status information on the source network side. Therefore, in the case of inter-gNB, further discussion is needed on how to control the release of the relay path during path switching. In other words, the timing of the successful transmission of the path switch command and the release of the relay should be specified.

[0055] Embodiments of the present disclosure provide a solution for path switching. In the present disclosure, the successful transmission of the path switching configuration to the terminal device can be determined and / or notified to the source network device and / or the relay terminal device. For the source network device, the source network device can generate a second message for reconfiguring the relay path in response to the successful transmission of the path switching configuration. Alternatively or additionally, the relay terminal device can apply the path switching configuration until the successful transmission of the path switching configuration.

[0056] In this way, it is ensured that the relay path can be released after the transmission of the path switching configuration is successful. As a result, the communication continuity of the remote UE is ensured.

[0057] For ease of discussion, some terms used in the following description are listed below: Direct network connection: refers to a network connection mode in which there is no relay terminal device / relay UE between the terminal device and the network device; sometimes also called a direct path. Indirect network connection: refers to a network connection mode in which a relay terminal device / relay UE exists between the terminal device and the network device; sometimes also called a relay path or an indirect path. • First network device: refers to a network entity, which may be a source network device during a path switch. · Second network device: refers to a network entity, which may be a target network device during path switching. ·First terminal device, referring to the terminal entity to be switched. In some embodiments, the first terminal device is initially connected to the first network device via a relay path (also referred to as a source path). In addition, the first terminal device is to be switched to a target path so that the first terminal device can be connected to the second network device. In some embodiments, the target path is a direct path. Alternatively, in some other embodiments, the target path is an indirect path; the first terminal device is sometimes also referred to as a remote terminal device. The second terminal device refers to a terminal entity that is a relay terminal device in the source path; sometimes also referred to as a source relay terminal device. Another second terminal device refers to a terminal entity that is a relay terminal device in the target path; sometimes also referred to as a target relay terminal device. Relay path: refers to any of the following: a path between a network device and a remote terminal device via one or more relay terminal devices, a path between a remote terminal device and a relay terminal device (i.e., a PC5 connection / side link connection / D2D connection), or a path between a relay terminal device and a network device. ·Successful transmission of path switching configuration / command: refers to any of the following: the path switching configuration / command has been successfully received by the terminal device, the successful completion of the path switching to the second network device / target device, the successful access to the second network device / target device, or the success / completion of the path switching to the second network device / target device.

[0058] In the present disclosure, the terms "path switch configuration", "path switch command", "RRC reconfiguration with path switch command", and "RRC reconfiguration for path switching" can be used interchangeably; the terms "path switch" and "path switching" can be used interchangeably; the terms "relay path" and "relaying path" can be used interchangeably.

[0059] In some embodiments, the message / signaling "HO Command" is used for I2D scenario and the message / signaling "Path Switch" is used for I2I scenario.

[0060] The principles and implementations of the present disclosure will be described in detail below with reference to the accompanying drawings. Example of a communication network

[0061] Figure 2AAn example communication environment 200 is shown in which an example embodiment of the present disclosure may be implemented. The communication environment 200 includes a plurality of terminal devices and network devices. Figure 2A As shown, the communication environment 200 includes a network device 210-1 and a network device 210-2. For the purpose of discussion, the network device 210-1 and the network device 210-2 are collectively referred to as the network device 210, or are individually referred to as the first network device 210-1 (i.e., sometimes referred to as the source gNB) and the second network device 210-2 (i.e., sometimes referred to as the target gNB).

[0062] exist Figure 2A In the specific example embodiment, the first network device 210-1 and the second network device 220-2 are located in different physical devices, and thus the inter-gNB network structure is supported in the communication environment 200.

[0063] The communication environment 200 also includes a terminal device 220-1, a terminal device 220-2, and a terminal device 220-3. At time point T0, the terminal device 220-1 communicates with the first network device 210-1 via the terminal device 220-2 (i.e., via an indirect path / relay path). In the following, the terminal device 220-1 may move over time, or the channel condition of the terminal device 220-1 may deteriorate, which causes the connection between the terminal device 220-1 and the network device 210-1 to need to be changed, for example, the terminal device 220-1 may be switched to another path (also referred to as a target path).

[0064] exist Figure 2A In a specific example embodiment, at time point T1, terminal device 220-1 may be switched to a target path with second network device 210-2. In some embodiments, the target path is a direct path, i.e., terminal device 210-1 communicates directly with second network device 210-2. Alternatively, in some other embodiments, the target path is an indirect path, i.e., terminal device 210-1 communicates with network device 210-2 via terminal device 220-3.

[0065] Figure 2B A signaling diagram illustrating a process 240 for communications according to some embodiments of the present disclosure is shown.

[0066] like Figure 2BAs shown, the source gNB issues a handover request message to the target gNB, thereby delivering a transparent RRC container with the necessary information to prepare the handover on the target side. The information includes at least the target cell ID, KgNB*, the cell radio network temporary identity (C-RNTI) of the UE in the source gNB, the radio resource management (RRM) configuration including the UE inactive time, the basic AS configuration including antenna information and downlink (DL) carrier frequency, the current quality of service (QoS) flow to DRB mapping rules applied to the UE, the signaling radio bearer 1 (SRB1) from the source gNB, the UE capabilities for different RATs, the protocol data unit (PDU) session related information, and may include the measurement information reported by the UE, which includes beam related information (if available). The PDU session related information includes slice information and (multiple) QoS flow level QoS profiles. The source gNB may also request a dual active protocol stack (DAPS) handover for one or more data radio bearers (DRBs).

[0067] In some embodiments, admission control may be performed by the target gNB. If slice information is sent to the target gNB, slice-aware admission control shall be performed. If a PDU session is associated with an unsupported slice, the target gNB shall reject such a PDU session.

[0068] In some embodiments, the target gNB prepares the handover using Layer 1 (L1) / L2 and sends a handover request confirmation to the source gNB, which includes a transparent container to be sent as an RRC message to the UE to perform the handover. The target gNB also indicates whether the DAPS handover is accepted.

[0069] In some embodiments, the source gNB triggers Uu handover by sending an RRCReconfiguration message to the UE, which contains the information required to access the target cell: at least the target cell ID, the new C-RNTI, the target gNB security algorithm identifier for the selected security algorithm. It may also include a set of dedicated RACH resources, the association between random access channel (RACH) resources and (multiple) synchronization signals and PBCH blocks SSB, the association between RACH resources and (multiple) UE-specific channel state information (CSI)-reference signal (RS) configurations, common RACH resources and system information of the target cell, etc.

[0070] In some embodiments, the UE synchronizes to the target cell and completes the RRC handover procedure by sending an RRCReconfigurationComplete message to the target gNB. In case of DAPS handover, the UE does not detach from the source cell upon receiving the RRCReconfiguration message. The UE releases the source resources and configuration and stops DL / UL reception / transmission with the source upon receiving an explicit release from the target node.

[0071] In some embodiments, in case of DAPS handover, the target gNB sends a handover success message to the source gNB to inform the UE that it has successfully accessed the target cell. In return, the source gNB sends an SN status transfer message for the DRB configured with DAPS.

[0072] In some embodiments, the 5GC (such as the Access and Mobility Management Function AMF or the User Plane Function UPF) switches the DL data path to the target gNB. The UPF sends one or more "end marker" packets to the source gNB on the old path for each PDU session / channel, and may then release any U-plane / TNL resources to the source gNB.

[0073] In some embodiments, upon receiving the Path Switch Request Ack message from the AMF, the target gNB sends a UE Context Release to inform the source gNB that the handover is successful. The source gNB may then release the radio and C-plane related resources associated with the UE context. Any ongoing data forwarding may continue.

[0074] Reference now Figure 2C , which shows another example communication environment 260. Figure 2C As shown, path switching can be performed between a direct path and an indirect path (ie, I2D and D2I), and can also be performed between an indirect path and an indirect path (ie, I2I).

[0075] It should be understood that FIG. 2A to FIG. 2C The number of devices and cells in the communication network is given for the purpose of illustration and does not imply any limitation to the present disclosure. The communication network may include any suitable number of network devices and / or terminal devices suitable for implementing the implementation of the present disclosure.

[0076] In some embodiments, the terminal device 220 and the network device 210 can communicate with each other via a channel such as a wireless communication channel on an air interface (e.g., a Uu interface). The wireless communication channel may include a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), a physical random access channel (PRACH), a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), and a physical broadcast channel (PBCH). Of course, any other suitable channel is also feasible.

[0077] The communications in the communication network 100 may conform to any suitable standard, including but not limited to Global System for Mobile Communications (GSM), Long Term Evolution (LTE), LTE Evolution, Advanced LTE (LTE-A), New Radio (NR), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), Machine Type Communications (MTC), etc. The embodiments of the present disclosure may be performed according to any generation of communication protocols currently known or developed in the future. Examples of communication protocols include but are not limited to first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, 5.5G, advanced 5G networks, or sixth generation (6G) networks. Example for path switching processing

[0078] It should be understood that, although feature(s) / operations(s) are discussed separately in particular example embodiments, these feature(s) / operations(s) described in different example embodiments may be used in any suitable combination unless clearly indicated to the contrary.

[0079] In addition, in the following description, some interactions (e.g., exchanging (multiple) configurations, etc.) are performed between the terminal device 220 and the network device 210. It should be understood that the interaction can be implemented in a single signaling / message or multiple signaling / messages, including system information, radio resource control (RRC) messages, downlink control information (DCI) messages, uplink control information (UCI) messages, medium access control (MAC) control elements (CE), sidelink relay adaptation protocol (SRAP), etc. The present disclosure is not limited in this regard.

[0080] In the following, some example embodiments will be discussed for the I2D scenario. It should be understood that the I2D scenario is only for illustrative purposes and does not imply any limitation. That is, the example embodiments discussed for I2D are also applicable to the I2I scenario. For the sake of brevity, the same or similar content is omitted.

[0081] The following will refer to Figure 3 Describe the principles and implementations of the present disclosure in detail. Figure 3 A signaling diagram illustrating a communication process 300 according to some example embodiments of the present disclosure is shown. For discussion purposes, reference will be made to FIG. 2A to FIG. 2C Process 300 is described.

[0082] Process 300 may involve a first network device 210-1 (i.e., a source network device), a second network device 210-2 (i.e., a target network device), a first terminal device 220-1 (i.e., a remote terminal device), a second terminal device 220-2 (i.e., a source relay terminal device), and a CN device. In addition, process 300 may optionally involve another second terminal device 220-3 (i.e., a target relay terminal device).

[0083] exist Figure 3 In the specific embodiment of FIG. 1 , the first terminal device 220 - 1 is initially connected to the first network device 210 - 1 via the second terminal device 220 - 2 .

[0084] In operation, the first terminal device 220-1 may optionally be configured 301 to measure and report measurement results. Based on the measurement results, the first network device 210-1 may determine 302 to perform a path switch. In the following, the first network device 210-1 sends 303 a handover (HO) request to the second network device 210-2, and receives 304 a HO confirmation (ACK) from the second network device 210-2.

[0085] In some embodiments, the target path during path switching is a direct path or an indirect path.

[0086] In some embodiments, the first network device 210-1 sends 305 a path switching configuration (e.g., an RRC reconfiguration for path switching) to the first terminal device. However, the transmission of the path switching configuration may sometimes fail. If the transmission of the path switching configuration fails, a retransmission of the path switching configuration 305-1 is required, and the retransmission of the path switching configuration requires a PC5 connection between the first terminal device 220-1 and the second terminal device 220-2.

[0087] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0088] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0089] According to some embodiments of the present disclosure, the release of the relay path (including any of the connection between the first terminal device 220-1 and the second terminal device 220-2, the connection between the first terminal device 220-1 and the first network device 210-1, and the connection between the second terminal device 220-2 and the first network device 210-1) can be controlled. In particular, the release of the relay path can be performed after the successful transmission of the path switching configuration.

[0090] In some embodiments, the first network device 210-1 may send a second message for reconfiguring the relay path to the second terminal device 220-2, wherein the second message may trigger the release of the relay path at the second terminal device 220-2. In view of this, the transmission timing of the second message may be controlled. As a general rule, the first network device 210-1 controls the transmission of the second message to be performed after the successful transmission of the path switching configuration to the first terminal device 220-1. In other words, the first network device 210-1 controls the transmission of the second message to be performed after the first terminal device 220-1 successfully completes the path switching or successfully accesses the second network device 210-2. Some example processes are discussed below.

[0091] In some embodiments, the first network device 210-1 receives a first message indicating successful transmission of the path switching configuration to the first terminal device 220-1, and then sends 335 a second message to the second terminal device 220-2 for reconfiguring the relay path. As a result, the PC5 connection between the first terminal device 220-1 and the second terminal device 220-2 can be released 350.

[0092] In some embodiments, the first message may indicate the successful transmission of the path switching configuration in an explicit manner. Specifically, the first message includes an indication indicating the successful transmission of the path switching configuration to the first terminal device.

[0093] Alternatively, in some other embodiments, the first message may indicate the successful transmission of the path switching configuration in an implicit manner. Specifically, some existing signaling may be reused to indicate the successful transmission. In addition, when reusing existing signaling, the existing signaling may also include an explicit indication indicating the successful transmission of the path switching configuration.

[0094] Furthermore, in some embodiments, the first message may be received from any of the second network device 210-2, the second terminal device 220-2, or a CN device. A detailed description will be discussed below.

[0095] like Figure 3 As shown, in some embodiments, the first message is received 320-3 from the second network device 210-2. For better understanding, now refer to Figure 4A, which shows a signaling diagram illustrating a communication process 400 according to some example embodiments of the present disclosure. For the purpose of discussion, reference will be made to Figure 3 Describe process 400. That is, Figure 3 and Figure 4A The same reference numerals in the figures refer to the same physical meanings.

[0096] In some embodiments, after receiving a fourth message regarding a successful transmission (or successful switching) of the path switching configuration, the second network device 220-2 sends 410 a first message to the first network device 210-1, wherein the first message may indicate a success of the (side link relay) path switching (i.e., a successful transmission of the path switching configuration).

[0097] In addition, in some embodiments, the second message is sent only in the case of an I2D / I2I path switching scenario.

[0098] like Figure 4A As shown, upon receiving the first message, the first network device 210-1 can determine the successful access to the target cell of the first terminal device 210 or the success of the path switching, and then the first network device 210-1 can send 335 a second message (such as, an RRCReconfiguration message) to the second terminal device 220-2 to reconfigure the relay path (such as, the connection between the second terminal device 220-2 and the first network device 210-1 and / or the connection between the second terminal device 220-2 and the first terminal device 220-1, for example, to release the PC5 relay RLC channel).

[0099] Additionally, in some embodiments, the second network device 210 - 2 may be notified by the first network device 210 - 1 that the first terminal device 220 - 1 is connected to the first network device 210 - 1 via an indirect path before the path switching.

[0100] In addition, from the perspective of the second network device 210-2, the successful transmission of the path switching configuration can be implied / determined after receiving the fourth message from another device. For example, the second network device 210-2 receives 322 an RRC reconfiguration completion message from the first terminal device 220-1, wherein the RRC reconfiguration completion message is sent in response to a random access (RA) 321 process of the second network device 210-2. For another example, the second network device 210-2 receives a path switching request confirmation from a CN device (such as an AMF).

[0101] In some embodiments, the target path is a direct path or an indirect path. Figure 3As shown, in the case where the target path is an indirect path, the PC5 connection is established 323 between the first terminal device 220-1 and another second terminal device 220-3 (i.e., the target relay terminal device). Thereafter, the first terminal device 220-1 sends 324-1 an RRC reconfiguration completion message to another second terminal device 220-3, and then the RRC reconfiguration completion message can be forwarded 324-2 to the second network device 210-2. As discussed above, the forwarded RRC reconfiguration completion message can be used as a fourth message.

[0102] In addition, when the other second terminal device 220-3 is in an idle state or an inactive state, after receiving the RRC reconfiguration completion message from the first terminal device 220-1, the other second terminal device 220-3 sends 325 an RRC establishment / recovery request to the second network device 210-2. Then, the other second terminal device 220-3 receives 326 an RRC establishment / recovery message from the second network device 210-1, and then the RRC establishment / recovery completion can be sent 327 to the second network device 210-2. In view of this, when the other second terminal device 220-3 is in an idle state or an inactive state, the fourth message can be one of the following: an RRC establishment request received from another second terminal device, an RRC resume request received from another second terminal device, An RRC Setup Complete is received from another second terminal device, or An RRC recovery completion is received from another second terminal device.

[0103] In this case, if Figure 3 As shown, the second network device 210-2 can send 320-2 a first message to the first network device to indicate the successful transmission of the path switching configuration. That is, the second network device 210-2 uses the access of the target relay UE (i.e., another second terminal device 220-3) as a trigger for sending the first message. In this case, the first message can be sent via a newly defined Xn message. In addition, in the case of I2D path switching and / or I2I path switching, the first message can be sent.

[0104] For a better understanding, now refer to Figure 4F , which shows a signaling diagram illustrating a process 495 of communication according to some example embodiments of the present disclosure, wherein a target path is an indirect path and a target relay terminal device (ie, another second terminal device 220-3) is in an idle state or an inactive state.

[0105] In addition, as discussed above, some existing signaling can be reused to indicate successful transmission. In some embodiments, after receiving the RRC reconfiguration completion message from the first terminal device 220-1, the second network device 210-2 can send a HANDOVER SUCCESS message to the first network device 210-1. In view of this, the HANDOVER SUCCESS message can be reused as the first message because the HANDOVER SUCCESS message can imply the successful transmission of the path switching configuration. In addition, in the case of I2D / I2I path switching, the first network device 210-1 can then send 335 a second message to the first terminal device 220-1.

[0106] In some embodiments, the handover success message itself implies the successful transmission of the path switch configuration. Alternatively, in some other embodiments, the handover success message includes an explicit indication indicating the successful transmission of the path switch configuration.

[0107] For a better understanding, now refer to Figure 4B , which shows a signaling diagram illustrating a communication process 420 according to some example embodiments of the present disclosure. Figure 4B As shown, the second network device 210 - 2 sends a switch success message to the first network device 210 - 1 to indicate the successful transmission of the path switch configuration.

[0108] In summary, the remote UE (i.e., the first terminal device 220-1) synchronizes to the target cell and completes the RRC handover process by sending an RRCReconfigurationComplete message to the target gNB (i.e., the second network device 210-2). In the case of DAPS handover, the target gNB sends a handover success message to the source gNB (i.e., the first network device 210-1) to notify the UE (i.e., the first terminal device 220-1) that it has successfully accessed the target cell. In return, the source μNB sends an SN status transfer message for the DRB configured with DAPS. In the case of I2D path handover or I2I path handover, the target gNB sends a handover success message to the source gNB to notify the UE that it has successfully accessed the target cell. At the time of the handover success message, the source gNB sends an RRCReconfiguration message (i.e., the second message) to the relay UE (i.e., the second terminal device 220-2), for example, to release the PC5 relay RLC channel.

[0109] In this way, the PC5 relay RLC channel or PC5 connection can be released at an appropriate time, and thus the resources of the relay UE can be released in time. In addition, the signaling interaction is performed with low complexity.

[0110] Alternatively, Figure 2BAs shown, in some embodiments, upon receiving the SN status transfer message from the first network device 210-1, the second network device 210-2 may send a path switch request to a CN device (such as an AMF). At the time of the path switch request, the CN device may send a path switch request confirmation to the second network device 210-2. Then, the second network device 210-2 may send a UE context release message to the first network device 210-1. In view of this, the UE context release message (UECONTEXTRELEASE) may be reused as the first message because the UE context release message may also imply the successful transmission of the path switch configuration. In addition, in the case of I2D / I2I path switching, the first network device 210-1 may then send 335 a second message to the first terminal device 220-1.

[0111] In some embodiments, the UE context release message itself implies the successful transmission of the path switch configuration.Alternatively, in some other embodiments, the UE context release message includes an explicit indication indicating the successful transmission of the path switch configuration.

[0112] For a better understanding, now refer to Figure 4C , which shows a signaling diagram illustrating a communication process 440 according to some example embodiments of the present disclosure. Figure 4C As shown, the second network device 210-2 sends a UE context release to the first network device 210-1 to indicate the successful transmission of the path switching configuration.

[0113] In summary, upon receiving a path switch request confirmation message from a CN device (such as an AMF), the target gNB (i.e., the second network device 210-2) sends a UE context release to notify the source gNB (i.e., the first terminal device 220-1) that the switch is successful. The source gNB can then release the radio and C-plane related resources associated with the UE context. In the case of an I2D / I2I path switch, the source gNB can then send an RRCReconfiguration message (i.e., a second message) to the relay UE (i.e., the second terminal device 220-2), for example, to release the PC5 relay RLC channel. Any ongoing data forwarding can continue.

[0114] In this way, the PC5 relay RLC channel can be released at an appropriate time and the signaling interaction is performed with low complexity.

[0115] In some embodiments, the timing of the configuration of the second terminal device 220-2 for the inter-gNB D2I / I2I path switch is specified as follows: The configuration of the second terminal device 220-2 for the inter-gNB path switch can be sent at any time after the source gNB (i.e., the first network device 210-1) receives the first message (e.g., UE context release) or the first message including an explicit indication indicating the successful transmission of the path switch configuration to the first network device 210-1 (e.g., UE context release includes an explicit indication). In other words, the first message itself implies the successful transmission of the path switch configuration, or the first message includes an explicit indication indicating the successful transmission of the path switch configuration.

[0116] Alternatively, in some other embodiments, the timing of configuring the second terminal device 220-2 for inter-gNB D2I / I2I path switching is specified as follows: the configuration of the second terminal device 220-2 for inter-gNB path switching can be sent at any time after the UE (i.e., the first terminal device 210-1) sends an RRCReconfigurationComplete message to the target gNB (i.e., the second network device 210-2).

[0117] Alternatively, in addition to receiving the first message from the second network device 210 - 2 , the first network device 210 - 1 may also receive 320 - 4 the first message from the CN device.

[0118] In some specific embodiments, the CN device may send a first message or a first message including an explicit indication indicating successful transmission of the path switching configuration to the first network device 210-1. In other words, the first message itself implies successful transmission of the path switching configuration, or the first message includes an explicit indication indicating successful transmission of the path switching configuration.

[0119] In addition, similar to the second network device 210 - 2 , the CN device may also reuse some existing signaling as the first message.

[0120] like Figure 2B As shown, in some embodiments, upon receiving a path switch request from the second terminal device, the AMF and (multiple) UPFs may perform path switching in the UPF. As a result, the (multiple) UPFs will send (multiple) end marker packets to the first network device 210-1. In view of this, the (multiple) end marker packets may be reused as the first message because the (multiple) end marker packets may imply the successful transmission of the path switch configuration.

[0121] For a better understanding, now refer to Figure 4D , which shows a signaling diagram illustrating a communication process 460 according to some example embodiments of the present disclosure. Figure 4DAs shown, the CN device sends an end marker packet to the first network device 210-1 to indicate the successful transmission of the path switching configuration.

[0122] Additionally, in some embodiments, the source gNB determines the success of the path switch if at least one “end marker” packet for each PDU session / tunnel has been received from the UPF(s), meaning that all relevant PDU sessions / tunnels have been switched at the CN.

[0123] Alternatively, in some embodiments, the source gNB determines the success of the path switch if at least one "end marker" packet for at least one PDU session / tunnel has been received from (multiple) UPFs, which means that at least part of the PDU session / tunnel has been switched at the CN.

[0124] In summary, in some embodiments, the core network (including the AMF and UPF) switches the DL data path to the target gNB (i.e., the second network device 210-2). The UPF sends one or more "end marker" packets to the source gNB (i.e., the first network device 210-1) on the old path of each PDU session / channel, and may then release any U-plane / TNL resources to the source gNB. If at least one "end marker" packet for each PDU session / channel has been received by the source gNB, the source gNB determines the success of the path switch and then sends an RRCReconfiguration message to the relay UE (i.e., the second terminal device 220-2), for example to release the PC5 relay RLC channel. In this way, the PC5 relay RLC channel may be released at an appropriate time.

[0125] Alternatively, the first network device 210-1 may also receive 320-1 a first message from the second terminal device 220-2. For example, the second terminal device 220-2 may send a first message or a first message including an explicit indication indicating successful transmission of the path switching configuration to trigger the first network device 210-1 to send a second message (i.e., an RRC reconfiguration message). In other words, the first message itself implies successful transmission of the path switching configuration, or the first message includes an explicit indication indicating successful transmission of the path switching configuration.

[0126] For a better understanding, now refer to Figure 4E , which shows a signaling diagram illustrating a communication process 480 according to some example embodiments of the present disclosure. Figure 4E As shown, in case of successful transmission of the path switching configuration, the second terminal device 220-2 sends 490 a first message to the first network device 210-1 to indicate the successful transmission of the path switching configuration.

[0127] In addition, in some embodiments, the second terminal device 220-2 sends the first message via MAC CE or RRC signaling (such as sidelink UE information, sidelink UE information NR message or UE assistance information).

[0128] From the perspective of the second terminal device 220, multiple factors may be used to determine the successful transmission of the path switching configuration. Example factors include, but are not limited to: Factor #1: The last packet data unit (PDU) of the PC5 radio link control (RLC) channel corresponding to the SRB associated with the first terminal device (including at least one of SIB1, SIB2, SIB3 or control signaling) is successfully sent to the first terminal device 220-1. That is, the last RLC PDU for the PC5 relay RLC channel corresponding to Uu RRC signaling / SRB1 is successfully transmitted. Factor #2: An acknowledgement of the last RLC PDU of a PC5 radio link control (RLC) channel corresponding to an SRB (including at least one of SIB1, SIB2, SIB3 or control signaling) associated with the first terminal device is received from the first terminal device. In other words, a PC5 RLC acknowledgement is received from the remote UE (i.e., the first terminal device 220-1) for the last RLC PDU of a PC5 relay RLC channel for Uu RRC signaling / SRB1. Factor #3: There are no packets buffered for the PC5 RLC channel corresponding to the SRB associated with the first terminal device 220-1 (including at least one of SIB1, SIB2, SIB3 or control signaling). In other words, the buffer for the PC5 relay RLC channel of Uu RRC signaling / SRB1 is empty. Factor #4: The length of time for which a packet of a PC5 radio link control (RLC) channel corresponding to an SRB (including at least one of SIB1, SIB2, SIB3, and control signaling) associated with the first terminal device is not received reaches a preconfigured length of time. In other words, no data / packet arrives during a predefined period of the PC5 relay RLC channel of Uu RRC signaling / SRB1. In addition, the preconfigured length of time or the predefined period is configured as a default value or is configured by one of the following: system information, RRC signaling, MAC CE, or downlink control information (DCI). Factor #5: The second terminal device is instructed by an upper layer to release the PC5 connection to the first terminal device, where the release of the PC5 connection may mean that the PC5 connection has been released or is about to be released. Factor #6: Receiving a third message from the first network device for triggering the second terminal device to apply the second message previously received.

[0129] Additionally, factor #1 and factor #3 may be used together when determining successful transmission of a path switching configuration. Alternatively, factor #1 and factor #4 may be used together when determining successful transmission of a path switching configuration. Alternatively, factor #2 and factor #3 may be used together when determining successful transmission of a path switching configuration. Alternatively, factor #2 and factor #4 may be used together when determining successful transmission of a path switching configuration.

[0130] It should be understood that the above exemplary factors and their combinations are given for illustrative purposes and do not imply any limitation. In addition, the above factors and other suitable factors may be used alone or in combination.

[0131] In order to ensure that the relay path is released reasonably, in addition to controlling the sending timing of the second message, the application timing of the second message can also achieve the same technical effect.

[0132] like Figure 3 As shown, after sending 305 a path switching configuration (such as, RRC reconfiguration) to the first terminal device 220-1, the first network device 210-1 sends 310-1 to the second terminal device 220-2 a second message for reconfiguring the relay path (such as, the connection between the second terminal device 220-2 and the first network device 210-1 and / or the connection between the second terminal device 220-2 and the first terminal device 220-1, for example, to release the PC5 relay RLC channel). For the second terminal device 220-2, the second terminal device 220-2 stores the second message without applying the second message, or stores a portion of the second message (for example, a portion related to the relay path or a portion related to releasing the PC5 relay RLC channel) without applying the portion. Next, if the second terminal device 220-2 determines that the path switching configuration has been successfully sent to the first terminal device 220-1, the second terminal device 220-2 can apply 340 the second message previously received. Since how the second terminal device 220 - 2 determines whether the path switching configuration has been successfully sent to the first terminal device 220 - 1 has been fully discussed in the previous part of this disclosure, the same content is omitted here only for the sake of brevity.

[0133] For a better understanding, now refer to Figure 5A , which shows a signaling diagram illustrating a communication process 500 according to some example embodiments of the present disclosure, wherein the second terminal device 220-2 determines that the path switching configuration has been successfully sent to the first terminal device 220-1 and applies 340 the second message previously received.

[0134] In addition, the application of the second message previously received may be triggered by a third message from the first network device 210-1. Figure 3 As shown, the first network device 210-1 determines 330 that the path switching configuration has been successfully sent to the first terminal device 220-1, and then sends 310-2 a third message for triggering the second terminal device 220-2 to apply the previously received second message or a portion of the second message. Upon receiving the third message, the second terminal device 220-2 applies 340 the previously received second message or a portion of the second message. Since how the first network device 210-1 determines whether the path switching configuration has been successfully sent to the first terminal device 220-1 has been fully discussed in the previous part of this disclosure, the same content is omitted here only for the sake of brevity.

[0135] For a better understanding, now refer to Figure 5B , which shows a signaling diagram illustrating a communication process 500 according to some example embodiments of the present disclosure, wherein upon receiving the third message, the second terminal device 220-2 determines that the path switching configuration has been successfully sent to the first terminal device 220-1, and applies 340 the second message previously received.

[0136] In some embodiments, the second terminal device 220-2 applies the previously received second message by at least one of the following: Release the relay path, Release the connection between the second terminal device 220-2 and the first network device 210-1, Release the connection between the second terminal device 220-2 and the first terminal device 220-1, releasing at least one of the PC5 relay RLC channel, the Uu relay RLC channel and the bearer mapping information, Release the PC5 channel, or Release the PC5-RRC connection.

[0137] In this way, the PC5 relay RLC channel can be released at an appropriate time without introducing excessive signaling overhead.

[0138] The above exemplary embodiments are mainly about how to avoid improper release of relay paths. In the following, exemplary embodiments about how to handle improper release of relay paths will be discussed.

[0139] In some embodiments, the first terminal device 220-1 may detect the relay connection failure caused by the second terminal device 220-2 locally releasing the PC5 relay RLC channel or releasing the PC5-RRC connection based on at least one of the following: Sidelink RLF, which will initiate an RRC reestablishment procedure for the second terminal device 220-2 in the RRC_CONNECTED state, such as, upon an indication from the sidelink RLC entity that the maximum number of retransmissions for a particular destination has been reached; or upon an indication from the MAC entity that the maximum number of consecutive Hybrid Automatic Repeat Request (HARQ) Discontinuous Transmission (DTX) for a particular destination has been reached; or The keep-alive process determines the local release of the PC5-RRC connection, such as, The expiration of timer T5080, or The maximum number of allowed retransmissions of the PROSE DIRECT LINK KEEPALIVEREQUEST message has been reached.

[0140] In some embodiments, if the first terminal device 220 - 1 detects a failure of the PC5 path between the first terminal device 220 - 1 and the second terminal device 220 - 2 via the keep-alive process, the first terminal device 220 - 1 initiates a reestablishment process with the second terminal device 220 - 2 .

[0141] In this way, improper release of relay paths can be handled gracefully. Method Example

[0142] Figure 6 600 according to some embodiments of the present disclosure. For example, the method 600 may be performed as follows: Figure 2A The first network device 210 - 1 is shown as being implemented.

[0143] At box 610, the first network device 210-1 receives a first message that explicitly or implicitly indicates a successful transmission of a path switching configuration to the first terminal device 220-1, and the first terminal device 220-1 is connected to the first network device 210-1 via a relay path including the second terminal device 220-2 and is switched to a target path between the first terminal device 220-1 and the second network device 210-2.

[0144] At block 610 , the first network device 210 - 1 sends to the second terminal device 220 - 2 one of: a second message for reconfiguring the relay path or a third message for triggering the second terminal device 220 - 2 to apply the previously received second message for reconfiguring the relay path.

[0145] In some embodiments, the first message includes an indication of successful transmission of the path switching configuration to the first terminal device 220-1, and the first network device 210-1 receiving the first message includes: receiving the first message from the second network device 210-2, the second terminal device 220-2 or one of the CN devices.

[0146] In some embodiments, the first message is a handover success message or a UE context release message received from the second network device 210 - 2 .

[0147] In some embodiments, the first message is at least one end marker packet corresponding to at least one corresponding PDU session of the first terminal device 220-1, and the first message is received from a CN device.

[0148] In some embodiments, the first message is received from the second terminal device 220-2 via one of MAC CE or RRC signaling.

[0149] In some embodiments, the target path is a direct path or an indirect path.

[0150] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0151] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0152] Figure 7 FIG. 7 is a flowchart of an example method 700 according to some embodiments of the present disclosure. For example, the method 700 may be performed as follows: Figure 2A The second network device 210 - 2 is shown to be implemented.

[0153] At box 710, the second network device 210-2 receives a fourth message that explicitly or implicitly indicates a successful transmission of the path switching configuration to the first terminal device 220-1, and the first terminal device 220-1 is connected to the first network device 210-1 via a relay path including the second terminal device 220-2 and is switched to a target path between the first terminal device 220-1 and the second network device 210-2.

[0154] At block 710 , the second network device 210 - 2 sends a first message to the first network device 210 - 1 , the first message explicitly or implicitly indicating successful transmission of the path switch configuration to the first terminal device 220 - 1 .

[0155] In some embodiments, the fourth message is a configuration completion message corresponding to the path switching configuration and received from one of: the first terminal device 220 - 1 or another second terminal device 220 - 3 included in the target path and serving as a relay device.

[0156] In some embodiments, the target path is an indirect path including another second terminal device 220-3, and the other second terminal device 220-3 is in an idle state or an inactive state, and the fourth message is one of the following: an RRC establishment request received from another second terminal device 220-3, an RRC recovery request received from another second terminal device 220-3, an RRC establishment completion received from another second terminal device 220-3, or an RRC recovery completion received from another second terminal device 220-3.

[0157] In some embodiments, the fourth message is a path switch confirmation message received from the CN device, and the path switch confirmation message corresponds to the path switch request sent by the second network device 210 - 2 to the CN device.

[0158] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device 220 - 1 .

[0159] In some embodiments, the first message is a handover success message or a UE context release message.

[0160] In some embodiments, the target path is a direct path or an indirect path.

[0161] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0162] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0163] Figure 8 800 according to some embodiments of the present disclosure. For example, the method 800 may be implemented in Figure 2A The implementation is shown at the second terminal device 220 - 2 .

[0164] At box 810, the second terminal device 220-2 determines the successful transmission of the path switching configuration to the first terminal device 220-1, the first terminal device 220-1 is connected to the first network device 210-1 via the relay path including the second terminal device 220-2 and is switched to the target path between the first terminal device 220-1 and the second network device 210-2.

[0165] At block 820 , the second terminal device 220 - 2 performs one of the following: sending a first message to the first network device 210 - 1 indicating successful transmission of the path switching configuration to the first terminal device 220 - 1 ; or applying a previously received second message for reconfiguring the relay path.

[0166] In some embodiments, the second message previously received by the application includes at least one of: releasing the relay path; releasing the connection between the second terminal device 220-2 and the first network device 210-1; or releasing the connection between the second terminal device 220-2 and the first terminal device 220-1.

[0167] In some embodiments, determining the successful transmission of the path switching configuration includes: determining the successful transmission of the path switching configuration based on at least one of the following: the last PDU of the PC5RLC channel corresponding to the SRB associated with the first terminal device 220-1 is successfully sent to the first terminal device 220-1; a confirmation of the last RLC PDU of the PC5RLC channel corresponding to the SRB associated with the first terminal device 220-1 is received from the first terminal device 220-1; there are no packets buffered for the PC5RLC channel corresponding to the SRB associated with the first terminal device 220-1; the time length for which packets for the PC5RLC channel corresponding to the SRB associated with the first terminal device 220-1 are not received reaches a preconfigured time length; the second terminal device 220-2 is instructed by the upper layer about the release of the PC5 connection for the first terminal device 220-1; or a third message is received from the first network device 210-1 to trigger the second terminal device 220-2 to apply the previously received second message.

[0168] In some embodiments, the preconfigured time length is configured as a default value or configured by one of the following: system information, RRC signaling, MAC CE, downlink control information.

[0169] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device 220 - 1 .

[0170] In some embodiments, the target path is a direct path or an indirect path.

[0171] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0172] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0173] Fig. 9 900 according to some embodiments of the present disclosure. For example, the method 900 may be implemented in Figure 2A It is implemented at the first terminal device 220 - 1 shown.

[0174] At box 910, the first terminal device 220-1 detects a failure of the PC5 path between the first terminal device 220-1 and the second terminal device 220-2 via a keep-alive process without receiving a path switching configuration from the second terminal device 220-2, and the first terminal device 220-1 is connected to the first network device 210-1 via the second terminal device 220-2.

[0175] At block 920 , the first terminal device 220 - 1 initiates a reestablishment process with the second terminal device 220 - 2 .

[0176] In some embodiments, detecting the failure of the PC5 path includes: detecting the failure of the PC5 path in response to at least one of the following: expiration of timer T5080 or the number of retransmissions of the PROSE DIRECT LINKKEEPALIVE REQUEST message reaching a third threshold number.

[0177] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0178] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0179] At box 1010, the CN device generates a first message that explicitly or implicitly indicates the successful transmission of the path switching configuration to the first terminal device 220-1, which is connected to the first network device 210-1 via a relay path including the second terminal device 220-2 and is switched to a target path between the first device and the second network device 210-2.

[0180] At block 1020, the CN device sends a first message to the first network device 210-1.

[0181] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device 220 - 1 .

[0182] In some embodiments, the first message is at least one end marker packet corresponding to at least one corresponding PDU session of the first terminal device 220-1.

[0183] In some embodiments, the target path is a direct path or an indirect path.

[0184] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0185] In some embodiments, the path switching configuration is associated with inter-gNB path switching. Examples of devices and equipment

[0186] Fig.11 1 is a simplified block diagram of a device 1100 suitable for implementing embodiments of the present disclosure. The device 1100 may be considered as Figure 2A Another example implementation of the first terminal device 220-1, the second terminal device 220-2, another second terminal device 220-3, the first network device 210-1 and the second network device 220-2 is shown. Therefore, the device 1100 can be implemented at the first terminal device 220-1, the second terminal device 220-2, another second terminal device 220-3, the first network device 210-1 and the second network device 220-2 or implemented as at least a part of the first terminal device 220-1, the second terminal device 220-2, another second terminal device 220-3, the first network device 210-1 and the second network device 220-2.

[0187] As shown, the device 1100 includes a processor 1110, a memory 1120 coupled to the processor 1110, a suitable transmitter (TX) / receiver (RX) 1140 coupled to the processor 1110, and a communication interface coupled to the TX / RX 1140. The memory 1110 stores at least a portion of the program 1130. The TX / RX 1140 is used for bidirectional communication. The TX / RX 1140 has at least one antenna to facilitate communication, although in fact the access node mentioned in this application may have several antennas. The communication interface may represent any interface required for communication with other network elements, such as an X2 / Xn interface for bidirectional communication between eNB / gNB, an S1 / NG interface for communication between a mobility management entity (MME) / access and mobility management function (AMF) / SGW / UPF and an eNB / gNB, a Un interface for communication between an eNB / gNB and a relay node (RN), or a Uu interface for communication between an eNB / gNB and a terminal device.

[0188] Assume that program 1130 includes program instructions that, when executed by associated processor 1110, enable device 1100 to operate in accordance with embodiments of the present disclosure, as described herein with reference to Figures 2A to 10 The embodiments herein may be implemented by computer software executable by a processor 1110 of the device 1100, or by hardware, or by a combination of software and hardware. The processor 1110 may be configured to implement various embodiments of the present disclosure. In addition, the combination of the processor 1110 and the memory 1120 may form a processing component 1150 suitable for implementing various embodiments of the present disclosure.

[0189] The memory 1120 may be of any type suitable for a local technology network and may be implemented using any suitable data storage technology, such as non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory, as non-limiting examples. Although only one memory 1120 is shown in the device 1100, there may be several physically different memory modules in the device 1100. As non-limiting examples, the processor 1110 may be of any type suitable for a local technology network and may include one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device 1100 may have multiple processors, such as a dedicated integrated circuit chip that is time-slave to a clock synchronized with a main processor.

[0190] In some embodiments, the first network device 210-1 includes a circuit system configured to: receive a first message that explicitly or implicitly indicates a successful transmission of a path switching configuration to the first terminal device 220-1, the first terminal device 220-1 being connected to the first network device 210-1 via a relay path including the second terminal device 220-2 and being switched to a target path between the first terminal device 220-1 and the second network device 210-2; and send to the second terminal device 220-2 one of: a second message for reconfiguring the relay path, or a third message for triggering the second terminal device 220-2 to apply the previously received second message for reconfiguring the relay path.

[0191] In some embodiments, the first message includes an indication of successful transmission of the path switching configuration to the first terminal device 220-1, and the first network device 210-1 receiving the first message includes: receiving the first message from one of the second network device 210-2, the second terminal device 220-2 or the CN device.

[0192] In some embodiments, the first message is a handover success message or a UE context release message received from the second network device 210 - 2 .

[0193] In some embodiments, the first message is at least one end marker packet corresponding to at least one corresponding PDU session of the first terminal device 220-1, and the first message is received from a CN device.

[0194] In some embodiments, the first message is received from the second terminal device 220-2 via one of MAC CE or RRC signaling.

[0195] In some embodiments, the target path is a direct path or an indirect path.

[0196] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0197] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0198] In some embodiments, the second network device 210-2 includes a circuit system configured to: receive a fourth message explicitly or implicitly indicating a successful transmission of a path switching configuration to the first terminal device 220-1, the first terminal device 220-1 being connected to the first network device 210-1 via a relay path including the second terminal device 220-2 and being switched to a target path between the first terminal device 220-1 and the second network device 210-2; and send a first message to the first network device 210-1 explicitly or implicitly indicating a successful transmission of the path switching configuration to the first terminal device 220-1.

[0199] In some embodiments, the fourth message is a configuration completion message corresponding to the path switching configuration and received from one of: the first terminal device 220 - 1 or another second terminal device 220 - 3 included in the target path and serving as a relay device.

[0200] In some embodiments, the target path is an indirect path including another second terminal device 220-3, and the other second terminal device 220-3 is in an idle state or an inactive state, and the fourth message is one of the following: an RRC establishment request received from another second terminal device 220-3, an RRC recovery request received from another second terminal device 220-3, an RRC establishment completion received from another second terminal device 220-3, or an RRC recovery completion received from another second terminal device 220-3.

[0201] In some embodiments, the fourth message is a path switch confirmation message received from the CN device, and the path switch confirmation message corresponds to the path switch request sent by the second network device 210 - 2 to the CN device.

[0202] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device 220 - 1 .

[0203] In some embodiments, the first message is a handover success message or a UE context release message.

[0204] In some embodiments, the target path is a direct path or an indirect path.

[0205] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0206] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0207] In some embodiments, the second terminal device 220-2 includes a circuit system configured to: determine a successful transmission of a path switching configuration to the first terminal device 220-1, the first terminal device 220-1 being connected to the first network device 210-1 via a relay path including the second terminal device 220-2 and being switched to a target path between the first terminal device 220-1 and the second network device 210-2; and perform one of the following: sending a first message to the first network device 210-1 indicating the successful transmission of the path switching configuration to the first terminal device 220-1; or applying a previously received second message for reconfiguring the relay path.

[0208] In some embodiments, the second message previously received by the application includes at least one of: releasing the relay path; releasing the connection between the second terminal device 220-2 and the first network device 210-1; or releasing the connection between the second terminal device 220-2 and the first terminal device 220-1.

[0209] In some embodiments, determining the successful transmission of the path switching configuration includes: determining the successful transmission of the path switching configuration based on at least one of the following: the last PDU of the PC5RLC channel corresponding to the SRB associated with the first terminal device 220-1 is successfully sent to the first terminal device 220-1; a confirmation of the last RLC PDU of the PC5RLC channel corresponding to the SRB associated with the first terminal device 220-1 is received from the first terminal device 220-1; there are no packets buffered for the PC5RLC channel corresponding to the SRB associated with the first terminal device 220-1; the time length for which packets for the PC5RLC channel corresponding to the SRB associated with the first terminal device 220-1 are not received reaches a preconfigured time length; the second terminal device 220-2 is instructed by the upper layer about the release of the PC5 connection for the first terminal device 220-1; or a third message is received from the first network device 210-1 to trigger the second terminal device 220-2 to apply the previously received second message.

[0210] In some embodiments, the preconfigured time length is configured as a default value or configured by one of the following: system information, RRC signaling, MAC CE, downlink control information.

[0211] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device 220 - 1 .

[0212] In some embodiments, the target path is a direct path or an indirect path.

[0213] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0214] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0215] In some embodiments, the first terminal device 220-1 includes a circuit system configured to: detect a failure of a PC5 path between the first terminal device 220-1 and the second terminal device 220-2 via a keep-alive process without receiving a path switching configuration from the second terminal device 220-2, the first terminal device 220-1 being connected to the first network device 210-1 via the second terminal device 220-2; and initiate a reconstruction process with the second terminal device 220-2.

[0216] In some embodiments, detecting the failure of the PC5 path includes: detecting the failure of the PC5 path in response to at least one of the following: expiration of timer T5080 or the number of retransmissions of the PROSE DIRECT LINKKEEPALIVE REQUEST message reaching a third threshold number.

[0217] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0218] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0219] In some embodiments, the CN device includes a circuit system configured to: generate a first message that explicitly or implicitly indicates a successful transmission of a path switching configuration to a first terminal device 220-1, the first terminal device 220-1 being connected to the first network device 210-1 via a relay path including the second terminal device 220-2 and being switched to a target path between the first device and the second network device 210-2; and send the first message to the first network device 210-1.

[0220] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device 220 - 1 .

[0221] In some embodiments, the first message is at least one end marker packet corresponding to at least one corresponding PDU session of the first terminal device 220-1.

[0222] In some embodiments, the target path is a direct path or an indirect path.

[0223] In some embodiments, the path switching configuration is associated with I2D path switching or I2I path switching.

[0224] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0225] The term "circuitry" used herein may refer to a combination of hardware circuits and / or hardware circuits and software. For example, a circuit system may be a combination of analog and / or digital hardware circuits and software / firmware. As another example, a circuit system may be any part of a hardware processor with software, including (multiple) digital signal processors, software, and (multiple) memories, which work together to enable devices such as terminal devices or network devices to perform various functions. In yet another example, a circuit system may be a hardware circuit and / or processor, such as a microprocessor or a part of a microprocessor, that requires software / firmware for operation, but when not required for operation, the software may not exist. As used herein, the term circuit system also encompasses only a hardware circuit or (multiple) processor or a part of a hardware circuit or (multiple) processor and its (or their) accompanying software and / or firmware implementation.

[0226] In summary, the embodiments of the present disclosure provide the following solutions.

[0227] In one solution, a communication method includes: receiving a first message at a first network device, the first message explicitly or implicitly indicating a successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to the first network device via a relay path including a second terminal device and being switched to a target path between the first terminal device and the second network device; and sending to the second terminal device one of: a second message for reconfiguring the relay path or a third message for triggering the second terminal device to apply a previously received second message for reconfiguring the relay path.

[0228] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device, and wherein receiving the first message includes: receiving the first message from one of the second network device, the second terminal device, or a core network (CN) device.

[0229] In some embodiments, the first message is a handover success message or a user equipment (UE) context release message received from the second network device.

[0230] In some embodiments, the first message is at least one end marker packet corresponding to at least one corresponding packet data unit (PDU) session of the first terminal device, and the first message is received from a core network (CN) device.

[0231] In some embodiments, the first message is received from the second terminal device via one of a Medium Access Control (MAC) Control Element (CE) or a Radio Resource Control (RRC) signaling.

[0232] In some embodiments, the target path is a direct path or an indirect path.

[0233] In some embodiments, the path switching configuration is associated with an indirect-to-direct (I2D) path switching or an indirect-to-indirect (I2I) path switching.

[0234] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0235] In one solution, a communication device includes: a processor; and a memory coupled to the processor and storing thereon instructions that, when executed by the processor, cause the communication device to perform any of the above methods.

[0236] In one solution, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causes the at least one processor to perform any of the above methods.

[0237] In another solution, a communication device includes: a processor configured to cause the device to execute any of the above methods.

[0238] In one solution, a method of communication includes: receiving a fourth message at a second network device, the fourth message explicitly or implicitly indicating a successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to the first network device via a relay path including the second terminal device and being switched to a target path between the first terminal device and the second network device; and sending a first message to the first network device, the first message explicitly or implicitly indicating a successful transmission of the path switching configuration to the first terminal device.

[0239] In some embodiments, the fourth message is a configuration completion message corresponding to the path switching configuration and received from one of: the first terminal device or another second terminal device included in the target path and serving as a relay device.

[0240] In some embodiments, the target path is an indirect path including another second terminal device, and the other second terminal device is in an idle state or an inactive state, and wherein the fourth message is one of: a radio resource control (RRC) establishment request received from another second terminal device, an RRC recovery request received from another second terminal device, an RRC establishment completion received from another second terminal device, or an RRC recovery completion received from another second terminal device.

[0241] In some embodiments, the fourth message is a path switch confirmation message received from a core network (CN) device, and the path switch confirmation message corresponds to a path switch request sent by the second network device to the CN device.

[0242] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device.

[0243] In some embodiments, the first message is a handover success message or a user equipment (UE) context release message.

[0244] In some embodiments, the target path is a direct path or an indirect path.

[0245] In some embodiments, the path switching configuration is associated with an indirect-to-direct (I2D) path switching or an indirect-to-indirect (I2I) path switching.

[0246] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0247] In one solution, a communication device includes: a processor; and a memory coupled to the processor and storing thereon instructions that, when executed by the processor, cause the communication device to perform any of the above methods.

[0248] In one solution, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causes the at least one processor to perform any of the above methods.

[0249] In another solution, a communication device includes: a processor configured to cause the device to perform any of the above methods.

[0250] In one solution, a method of communication includes: determining, at a second terminal device, successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to a first network device via a relay path including the second terminal device and being switched to a target path between the first terminal device and the second network device; and performing one of the following: sending a first message to the first network device, the first message indicating the successful transmission of the path switching configuration to the first terminal device; or applying a previously received second message for reconfiguring the relay path.

[0251] In some embodiments, the second message previously received by the application includes at least one of the following: releasing the relay path; releasing the connection between the second terminal device and the first network device; or releasing the connection between the second terminal device and the first terminal device.

[0252] In some embodiments, determining the successful transmission of the path switching configuration includes: determining the successful transmission of the path switching configuration based on at least one of the following: the last packet data unit (PDU) for the PC5 radio link control (RLC) channel corresponding to the signaling radio bearer (SRB) associated with the first terminal device is successfully sent to the first terminal device; an acknowledgment of the last RLC PDU for the PC5 radio link control (RLC) channel corresponding to the signaling radio bearer (SRB) associated with the first terminal device is received from the first terminal device; there are no packets buffered for the PC5RLC channel corresponding to the signaling radio bearer (SRB) associated with the first terminal device; the time length for which packets for the PC5 radio link control (RLC) channel corresponding to the signaling radio bearer (SRB) associated with the first terminal device are not received reaches a preconfigured time length; the second terminal device is instructed by the upper layer about the release of the PC5 connection for the first terminal device; or a third message is received from the first network device to trigger the second terminal device to apply the previously received second message.

[0253] In some embodiments, the preconfigured time length is configured as a default value or configured by one of: system information, radio resource control (RRC) signaling, medium access control (MAC) control element (CE), or downlink control information.

[0254] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device.

[0255] In some embodiments, the target path is a direct path or an indirect path.

[0256] In some embodiments, the path switching configuration is associated with an indirect-to-direct (I2D) path switching or an indirect-to-indirect (I2I) path switching.

[0257] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0258] In one solution, a communication device includes: a processor; and a memory coupled to the processor and having stored thereon instructions that, when executed by the processor, cause the communication device to perform any of the above methods.

[0259] In one solution, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causes the at least one processor to perform any of the above methods.

[0260] In another solution, a communication device includes: a processor configured to cause the device to execute any of the above methods.

[0261] In one solution, a method of communication includes: detecting, at a first terminal device and via a keep-alive process, a failure of a PC5 path between the first terminal device and a second terminal device without receiving a path switching configuration from the second terminal device, the first terminal device being connected to a first network device via the second terminal device; and initiating a reconstruction process with the second terminal device.

[0262] In some embodiments, detecting the failure of the PC5 path includes: detecting the failure of the PC5 path in response to at least one of the following: expiration of timer T5080 or the number of retransmissions of the PROSE DIRECT LINKKEEPALIVE REQUEST message reaching a third threshold number.

[0263] In some embodiments, the path switching configuration is associated with an indirect-to-direct (I2D) path switching or an indirect-to-indirect (I2I) path switching.

[0264] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0265] In one solution, a communication device includes: a processor; and a memory coupled to the processor and having stored thereon instructions that, when executed by the processor, cause the communication device to perform any of the above methods.

[0266] In one solution, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causes the at least one processor to perform any of the above methods.

[0267] In another solution, a communication device includes: a processor configured to cause the device to execute any of the above methods.

[0268] In one solution, a method of communication includes: generating a first message at a core network (CN) device, the first message explicitly or implicitly indicating successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to the first network device via a relay path including a second terminal device and being switched to a target path between the first device and the second network device; and sending the first message to the first network device.

[0269] In some embodiments, the first message includes an indication of successful transmission of the path switch configuration to the first terminal device.

[0270] In some embodiments, the first message is at least one end marker packet corresponding to at least one corresponding packet data unit (PDU) session of the first terminal device.

[0271] In some embodiments, the target path is a direct path or an indirect path.

[0272] In some embodiments, the path switching configuration is associated with an indirect-to-direct (I2D) path switching or an indirect-to-indirect (I2I) path switching.

[0273] In some embodiments, the path switching configuration is associated with inter-gNB path switching.

[0274] In one solution, a communication device includes: a processor; and a memory coupled to the processor and having stored thereon instructions that, when executed by the processor, cause the communication device to perform any of the above methods.

[0275] In one solution, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causes the at least one processor to perform any of the above methods.

[0276] In another solution, a communication device includes: a processor configured to cause the device to execute any of the above methods.

[0277] In general, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are shown and described as block diagrams, flow charts, or using some other graphical representations, it will be understood that, as non-limiting examples, the boxes, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or controllers, or other computing devices, or some combination thereof.

[0278] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer executable instructions, such as computer executable instructions included in a program module, which are executed in a device on a target real or virtual processor to perform the above-referenced Figures 2A to 10 The process or method described. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The functions of the program modules can be combined or split between program modules as needed in various embodiments. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in both local and remote storage media.

[0279] The program code for executing the method of the present disclosure can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device so that the program code enables the functions / operations specified in the flow chart and / or block diagram to be implemented when executed by the processor or controller. The program code can be executed completely on the machine, partially on the machine, as an independent software package, partially on the machine and partially on a remote machine, or completely on a remote machine or server.

[0280] The above program code may be embodied on a machine-readable medium, which may be any tangible medium that may contain or store a program used by or in conjunction with an instruction execution system, device, or apparatus. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. More specific examples of machine-readable storage media will include an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0281] In addition, although operations are depicted in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown or in a continuous order, or performing all of the operations shown to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of the present disclosure, but should be interpreted as descriptions of features that may be specific to a specific embodiment. Certain features described in the context of a separate embodiment may also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments or in any suitable sub-combination, respectively.

[0282] Although the disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Instead, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method of communication, comprising: receiving, at a first network device, a first message, the first message explicitly or implicitly indicating successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to the first network device via a relay path including a second terminal device and being switched to a target path between the first terminal device and the second network device; as well as Send one of the following to the second terminal device: a second message, used to reconfigure the relay path, or The third message is used to trigger the second terminal device to apply the second message previously received for reconfiguring the relay path.

2. The method of claim 1 , wherein the first message includes an indication of the successful transmission of the path switching configuration to the first terminal device; and Wherein receiving the first message comprises: The first message is received from one of the second network device, the second terminal device, or a core network (CN) device. 3 . The method of claim 1 , wherein the first message is a handover success message or a user equipment (UE) context release message received from the second network device.

4. The method of claim 1, wherein the first message is at least one end marker packet corresponding to at least one corresponding packet data unit (PDU) session of the first terminal device, and the first message is received from a core network (CN) device. 5 . The method of claim 1 , wherein the path switching configuration is associated with an indirect-to-direct (I2D) path switching or an indirect-to-indirect (I2I) path switching.

6. A method of communication, comprising: receiving, at the second network device, a fourth message, the fourth message explicitly or implicitly indicating successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to the first network device via a relay path including the second terminal device and being switched to a target path between the first terminal device and the second network device; as well as A first message is sent to the first network device, wherein the first message explicitly or implicitly indicates the successful transmission of the path switching configuration to the first terminal device.

7. The method according to claim 6, wherein the fourth message is a configuration completion message corresponding to the path switching configuration and received from one of: The first terminal device, or Another second terminal device is included in the target path and serves as a relay device.

8. The method according to claim 6, wherein the target path is an indirect path including another second terminal device, and the another second terminal device is in an idle state or an inactive state, and The fourth message is one of the following: a radio resource control (RRC) establishment request received from said another second terminal device, an RRC resume request received from said another second terminal device, an RRC Setup Complete received from the other second terminal device, or An RRC recovery completion is received from the another second terminal device.

9. The method of claim 6, wherein the fourth message is a path switch confirmation message received from a core network (CN) device, the path switch confirmation message corresponding to a path switch request sent by the second network device to the CN device.

10. The method of claim 6, wherein the first message includes an indication indicating the successful transmission of the path switch configuration to the first terminal device.

11. The method of claim 6, wherein the first message is a handover success message or a user equipment (UE) context release message.

12. A method of communication, comprising: determining, at a second terminal device, successful transmission of a path switching configuration to a first terminal device, the first terminal device being connected to a first network device via a relay path including the second terminal device and being switched to a target path between the first terminal device and the second network device; as well as Do one of the following: sending a first message to the first network device, the first message indicating the successful transmission of the path switching configuration to the first terminal device; or A previously received second message for reconfiguring the relay path is applied.

13. The method according to claim 12, wherein the second message previously received by the application comprises at least one of the following: releasing the relay path; releasing the connection between the second terminal device and the first network device; or, Release the connection between the second terminal device and the first terminal device.

14. The method of claim 12, wherein determining the successful transmission of the path switching configuration comprises: The successful transmission of the path switching configuration is determined based on at least one of: a last packet data unit (PDU) for a PC5 radio link control (RLC) channel corresponding to a signalling radio bearer (SRB) associated with the first terminal device is successfully sent to the first terminal device; an acknowledgement of a last Radio Link Control (RLC) PDU for a PC5 Radio Link Control (RLC) channel corresponding to a Signalling Radio Bearer (SRB) associated with the first terminal device is received from the first terminal device; there are no packets buffered for a PC5 RLC channel corresponding to a signalling radio bearer (SRB) associated with the first terminal device; a length of time during which a packet for a PC5 radio link control (RLC) channel corresponding to an SRB associated with the first terminal device is not received reaches a preconfigured length of time; The second terminal device is instructed by an upper layer to release the PC5 connection to the first terminal device; or, A third message is received from the first network device for triggering the second terminal device to apply a previously received second message.

15. The method of claim 12, wherein the first message includes an indication indicating the successful transmission of the path switch configuration to the first terminal device.

16. A method of communication, comprising: detecting, at a first terminal device and via a keep-alive procedure, a failure of a PC5 path between the first terminal device and a second terminal device, without receiving a path switching configuration from the second terminal device, the first terminal device being connected to a first network device via the second terminal device; as well as Initiate a reestablishment process with the second terminal device.

17. The method of claim 16, wherein detecting the failure of the PC5 path comprises: The failure of the PC5 path is detected in response to at least one of: The expiration of timer T5080, or The number of retransmissions of the PROSE DIRECT LINK KEEPALIVE REQUEST message reaches a third threshold number.

18. A method of communication, comprising: generating a first message at a core network (CN) device, the first message explicitly or implicitly indicating successful transmission of a path switch configuration to a first terminal device, the first terminal device being connected to a first network device via a relay path including a second terminal device and being switched to a target path between the first device and the second network device; as well as The first message is sent to the first network device.

19. The method of claim 18, wherein the first message includes an indication indicating the successful transmission of the path switch configuration to the first terminal device.

20. The method of claim 18, wherein the first message is at least one end marker packet corresponding to at least one corresponding packet data unit (PDU) session of the first terminal device.

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