Method for device-to-device relay communication

Abstract

A wireless communication method for use in a third wireless terminal is disclosed. The method comprises: sending a first PC5 link establishment request to a fourth wireless terminal via a first relay terminal, the first PC5 link establishment request comprising first relay selection information; receiving a second PC5 link establishment request from a fourth wireless terminal via a second relay terminal, the second PC5 link establishment request including second relay selection information, selecting one of the first relay terminal or the second relay terminal based on the first relay selection message and the second relay selection information, and transmitting the selected one of the first relay terminal and the second relay terminal to the fourth wireless terminal. And establishing a PC5 link with the fourth wireless terminal via the selected relay terminal.

Description

Technical Field

[0001] The present application is directed generally to wireless communications, and in particular to fifth generation (5G) communications. Background Art

[0002] With the development of wireless multimedia services, the demand for high data rates and good user experience is increasing, resulting in higher requirements for the system compatibility and coverage of traditional cellular networks. On the other hand, due to application scenarios such as public safety, social networks, near-field data sharing, and local advertising, the demand for proximity services is also increasing. Traditionally, cellular networks using base stations as the center may have obvious limitations in supporting high data rates and proximity services. In order to meet such needs, device-to-device (D2D) communication technology is proposed. By applying D2D communication technology, the burden on cellular networks can be reduced, the power consumption of user equipment (UE) can be reduced, the data rate can be increased, and the robustness of the network infrastructure can be improved. Therefore, the demand for high data rates and proximity services is greatly met. In this context, D2D communication technology is also called proximity services (ProSe) or sidelink communication, where the interface between UEs is called PC5 interface.

[0003] To support a wider range of applications and services (e.g., indoor relay communication, smart agriculture, smart factories, public safety, etc.), sidelink-based relay communication can be used to extend coverage and improve power consumption. For example, sidelink-based communication can be applied to Figure 1 Two application scenarios are shown:

[0004] 1) UE to Network Relay (Mode 1): This type of relay is used for UEs in weak / no coverage areas. Figure 1 In the example, UE1 in a weak / no coverage area is allowed to communicate with the network (e.g., base station) through UE2 under network coverage. UE-to-network relay can help network operators extend coverage and increase network capacity. Figure 1 In the example, UE1 may be referred to as a remote UE, and UE2 may be referred to as a UE-to-network relay.

[0005] 2) UE-to-UE relay (Mode 2): For emergency situations where the network is not functioning properly (e.g., earthquake) or to extend the sidelink communication range, UEs may be allowed to communicate with each other via one or more relay UEs. For example, Figure 1 UE3 and UE4 in the example communicate with each other via UE5 or multiple relay UEs. UE5 can be called a UE-to-UE relay.

[0006] In Long Term Evolution (LTE), two UE-to-network relay technology solutions are provided, namely, an Internet Protocol (IP)-based layer (Layer 3 (L3)) relay technology solution and an access layer (Layer 2 (L2)) relay technology solution. Note that the layer 3 relay forwards data based on the target IP address / port number, and the layer 2 relay performs routing forwarding of control plane and user plane data to allow network operators (i.e., core network (CN) network elements and base stations) to effectively manage remote devices (i.e., remote UEs). Due to the significant differences between new radio (NR) side link communications and LTE side link communications (e.g., in terms of frame structure, quality of service (QoS) processing, bearer configuration and establishment, etc.), the LTE-based side link relay technology solution cannot be applied to 5G / NR systems. Therefore, it is necessary to provide new technical solutions for 5G / NR systems. Summary of the invention

[0007] The present application relates to a method, system and device for D2D communication, and in particular to discovery and selection / reselection of a relay for D2D communication.

[0008] The present disclosure relates to a wireless communication method for use in a first wireless terminal. The method comprises:

[0009] determining a relay terminal for communicating with the second wireless terminal, and

[0010] Relay information associated with the relay terminal is sent to the second wireless terminal.

[0011] Various embodiments may preferably implement the following features:

[0012] Preferably, the wireless communication method further comprises: determining that at least one relay selection trigger condition is satisfied.

[0013] Preferably, the relay information includes a layer 2 identifier of the relay terminal.

[0014] The present disclosure relates to a wireless communication method for use in a second wireless terminal. The method comprises:

[0015] receiving relay information associated with the relay terminal from the first wireless terminal, and

[0016] Based on the relay information, a PC5 link with the first wireless terminal is established via the relay terminal.

[0017] Various embodiments may preferably implement the following features:

[0018] Preferably, the relay information includes a layer 2 identifier of the relay terminal.

[0019] The present disclosure relates to a wireless communication method for use in a third wireless terminal. The method includes:

[0020] sending a first PC5 link establishment request to the fourth wireless terminal via the first relay terminal, wherein the first PC5 link establishment request includes first relay selection information,

[0021] receiving a second PC5 link establishment request from a fourth wireless terminal via a second relay terminal, wherein the second PC5 link establishment request includes second relay selection information,

[0022] selecting one of the first relay terminal or the second relay terminal based on the first relay selection information and the second relay selection information, and

[0023] A PC5 link with the fourth wireless terminal is established via the selected relay terminal.

[0024] Various embodiments may preferably implement the following features:

[0025] Preferably, the first relay selection information includes a first round-trip delay of a first PC5 link from the third wireless terminal via the first relay terminal to the fourth wireless terminal, and the second relay selection information includes a second round-trip delay of a second PC5 link from the fourth wireless terminal via the first relay terminal to the third wireless terminal.

[0026] Preferably, the first relay selection information includes a first timestamp associated with the first PC5 link establishment request, and the second relay selection information includes a second timestamp associated with the second PC5 link establishment request.

[0027] Preferably, the first relay selection information includes a first random number associated with the first PC5 link establishment request, and the second relay selection information includes a second random number associated with the second PC5 link establishment request.

[0028] Preferably, the first relay selection information includes a first layer 2 identifier of the third wireless terminal, and the second relay selection information includes a second layer 2 identifier of the fourth wireless terminal.

[0029] Preferably, selecting the second relay terminal based on the first relay selection information and the second relay selection information, and establishing a PC5 link with the fourth wireless terminal via the selected relay terminal includes:

[0030] A PC5 link establishment acceptance message is sent to the fourth wireless terminal via the second relay terminal.

[0031] Preferably, selecting the first relay terminal based on the first relay selection information and the second relay selection information, and establishing a PC5 link with the fourth wireless terminal via the selected relay terminal includes:

[0032] A PC5 link establishment accept message is received from the fourth wireless terminal via the first relay terminal.

[0033] The present disclosure relates to a wireless communication method for use in a fifth wireless terminal. The method includes:

[0034] Sending a first PC5 link establishment request to the sixth wireless terminal via the first relay terminal,

[0035] receiving a second PC5 link establishment request from a sixth wireless terminal via the second relay terminal, wherein the first link establishment request conflicts with the second link establishment request, and

[0036] After the predefined time, a seventh link establishment request for the sixth wireless terminal is initiated.

[0037] The present disclosure relates to a first wireless terminal. The first wireless terminal comprises:

[0038] a processor configured to determine a relay terminal for communicating with a second wireless terminal, and

[0039] A communication unit is configured to send relay information associated with the relay terminal to a second wireless terminal.

[0040] Various embodiments may preferably implement the following features:

[0041] Preferably, the processor is also configured to execute any one of the above-mentioned wireless communication methods.

[0042] The present disclosure relates to a second wireless terminal. The second wireless terminal includes:

[0043] a communication unit configured to receive relay information associated with a relay terminal from a first wireless terminal, and

[0044] A processor is configured to establish a PC5 link with the first wireless terminal via the relay terminal based on the relay information.

[0045] Various embodiments may preferably implement the following features:

[0046] Preferably, the processor is also configured to execute any one of the above-mentioned wireless communication methods.

[0047] The present disclosure relates to a third wireless terminal. The third wireless terminal includes:

[0048] a communication unit configured to: send a first PC5 link establishment request to a fourth wireless terminal via a first relay terminal, wherein the first PC5 link establishment request includes first relay selection information, and receive a second PC5 link establishment request from the fourth wireless terminal via a second relay terminal, wherein the second PC5 link establishment request includes second relay selection information, and

[0049] A processor configured to select one of the first relay terminal or the second relay terminal based on the first relay selection information and the second relay selection information, and establish a PC5 link with the fourth wireless terminal via the selected relay terminal.

[0050] Various embodiments may preferably implement the following features:

[0051] Preferably, the processor is also configured to execute any one of the above-mentioned wireless communication methods.

[0052] The present disclosure relates to a fifth wireless terminal. The fifth terminal includes:

[0053] a communication unit configured to: send a first PC5 link establishment request to a sixth wireless terminal via a first relay terminal, receive a second PC5 link establishment request from the sixth wireless terminal via a second relay terminal, wherein the first link establishment request conflicts with the second link establishment request, and

[0054] A processor is configured to initiate a seventh link establishment request for a sixth wireless terminal after a predefined time.

[0055] Various embodiments may preferably implement the following features:

[0056] Preferably, the processor is also configured to execute any one of the above-mentioned wireless communication methods.

[0057] The present disclosure relates to a computer program product, including a computer-readable program medium code stored thereon, and when the code is executed by a processor, the processor implements any one of the wireless communication methods described in the foregoing methods.

[0058] The exemplary embodiments disclosed herein are intended to provide features that will become apparent by reference to the following description in conjunction with the accompanying drawings. According to various embodiments, exemplary systems, methods, devices, and computer program products are disclosed herein. However, it should be understood that these embodiments are presented by way of example and not limitation, and it will be apparent to those of ordinary skill in the art who read this disclosure that various modifications may be made to the disclosed embodiments while remaining within the scope of this disclosure.

[0059] Therefore, the present disclosure is not limited to the exemplary embodiments and applications described and illustrated herein. In addition, the specific order and / or hierarchy of steps in the methods disclosed herein are merely exemplary methods. Based on design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be rearranged while remaining within the scope of the present disclosure. Therefore, it should be understood by those of ordinary skill in the art that the methods and techniques disclosed herein present various steps or actions in an example order, and unless otherwise expressly stated, the present disclosure is not limited to the specific order or hierarchy presented.

[0060] The present invention is described in detail by the independent claims. Preferred embodiments are defined in the dependent claims. In the following description, although many features may be designated as optional, it should be recognized that all features included in the independent claims should not be construed as optional.

[0061] The above aspects and other aspects and embodiments thereof are described in more detail in the drawings, the description and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A schematic diagram of the network is shown.

[0063] Figure 2 A schematic diagram showing a process according to an embodiment of the present disclosure is shown.

[0064] Figure 3 A schematic diagram showing a process according to an embodiment of the present disclosure is shown.

[0065] Figure 4 A schematic diagram showing a process according to an embodiment of the present disclosure is shown.

[0066] Figure 5 A schematic diagram showing a process according to an embodiment of the present disclosure is shown.

[0067] Figure 6 A schematic diagram showing a process according to an embodiment of the present disclosure is shown.

[0068] Figure 7 A schematic diagram showing a process according to an embodiment of the present disclosure is shown.

[0069] Figure 8 An example of a schematic diagram of a wireless terminal according to an embodiment of the present disclosure is shown.

[0070] Fig. 9 An example of a schematic diagram of a wireless network node according to an embodiment of the present disclosure is shown.

[0071] Fig.10 A flow chart of a method according to an embodiment of the present disclosure is shown.

[0072] Fig.11A flow chart of a method according to an embodiment of the present disclosure is shown.

[0073] Fig.12 A flow chart of a method according to an embodiment of the present disclosure is shown.

[0074] Fig.13 A flow chart of a method according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0075] Figure 2 A schematic diagram of a process according to an embodiment of the present disclosure is shown. Figure 2 In the embodiment, the second communication device may communicate with the first communication device, for example, via a direct link or an indirect link. Figure 2 The process shown includes the following steps:

[0076] Step 201: The second communication device detects that one or more relay selection / reselection triggering conditions are met.

[0077] Step 202: The second communication device selects a UE as a relay.

[0078] Step 203: The second communication device notifies / sends the first communication device the relay information. In one embodiment, the relay information includes the L2 ID of the relay UE.

[0079] Step 204: Upon / after receiving the relay information, the first communication device establishes a new (end-to-end) PC5 link with the second communication device via the relay.

[0080] Figure 3 A schematic diagram of a process according to an embodiment of the present disclosure is shown. Figure 3 In the present invention, the first communication device and the second communication device may need to establish a direct link with each other. Figure 3 The process shown includes the following steps:

[0081] Step 301: The first communication device sends an end-to-end DCR (Direct Communication Request) message to the second communication device via Relay 1, wherein the round trip delay RTD1 is included in the DCR message. For example, the round trip delay RTD1 may be associated with a relay link via Relay 1.

[0082] In one embodiment, the end-to-end DCR message in step 301 may be replaced by a PC5-S message (eg, PC5 Link Modification Request).

[0083] Step 302: The second communication device further sends an end-to-end DCR message to the first communication device via relay 2, wherein the round trip delay RTD2 is included in the DCR message. The round trip delay RTD2 may be associated with a relay link via relay 2.

[0084] In one embodiment, the end-to-end DCR message in step 302 may be replaced by a PC5-S message (eg, PC5 Link Modification Request).

[0085] Step 303: The first communication device compares RTD1 via relay 1 and RTD2 via relay 2. In this embodiment, RTD1 is higher than RTD2, and the first communication device sends a DCA (Directed Communication Acceptance) message to the second communication device via relay 2.

[0086] In an embodiment where RTD1 is higher than RTD2 , the second communication device sends a DCA (Directed Communication Acceptance) message to the first communication device via Relay 1 .

[0087] Figure 4 A schematic diagram of a process according to an embodiment of the present disclosure is shown. Figure 4 In the present invention, the first communication device and the second communication device may need to establish a direct link with each other. Figure 4 The process shown includes the following steps:

[0088] Step 401: The first communication device sends an end-to-end DCR message to the second communication device via relay 1, wherein the timestamp TS1 is included in the DCR message. For example, the timestamp TS1 may be associated with the transmission of the DCR message.

[0089] In one embodiment, the end-to-end DCR message in step 401 may be replaced by a PC5-S message (eg, PC5 Link Modification Request).

[0090] Step 402: The second communication device further sends an end-to-end DCR message to the first communication device via relay 2, wherein the timestamp TS2 is included in the DCR message. The timestamp TS2 may be associated with the transmission of the DCR message.

[0091] In one embodiment, the end-to-end DCR message in step 402 may be replaced by a PC5-S message (eg, PC5 Link Modification Request).

[0092] Step 403: The first communication device compares the timestamp TS1 with the timestamp TS2. If the timestamp TS1 is later than the timestamp TS2, the first communication device sends a DCA message to the second communication device via the relay 2.

[0093] If the timestamp TS1 is before the timestamp TS2 , the second communication device sends a DCA message to the first communication device via relay 1 .

[0094] Figure 5 A schematic diagram of a process according to an embodiment of the present disclosure is shown. Figure 5In the present embodiment, the first communication device and the second communication device may need to establish a PC5 link with each other. Figure 5 The process shown includes the following steps:

[0095] Step 501: The first / second communication device adds a random number (eg, 2 bits or 3 bits) to a direct link request message (per hop or end-to-end).

[0096] Step 502: If the first / second communication device has sent a direct link request message (per hop or end-to-end) to the second / first communication device before receiving a direct link request message (per hop or end-to-end) from each other, the first / second communication device determines / knows that a conflict has occurred.

[0097] Step 503: If a conflict occurs, the first / second communication device compares the random number in the sent direct link request message with the random number in the received direct link request message. The link retains a smaller (or larger) random number. In this embodiment, the direct link request message sent from the second communication device to the first communication device has a smaller random number. Therefore, the first communication device sends a direct link acceptance message to the second communication device via relay 2.

[0098] Figure 6 A schematic diagram of a process according to an embodiment of the present disclosure is shown. Figure 6 In the present embodiment, the first communication device and the second communication device may need to establish a PC5 link with each other. Figure 6 The process shown includes the following steps:

[0099] Step 601: A first communication device and a second communication device send a direct link request message to each other (per hop or end-to-end), wherein the direct link request message includes the L2 ID of the initial communication device. For example, a direct link request sent from a first communication device to a second communication device may include the L2 ID of the first communication device or another device that initiates the direct link request message.

[0100] Step 602: If the first / second communication device has sent a direct link request message (per hop or end-to-end) to the second / first communication device before receiving a direct link request message (per hop or end-to-end) from each other, the first / second communication device determines / knows that a conflict has occurred.

[0101] Step 603: If a conflict occurs, the first / second communication device compares the L2 ID in the sent direct link request message with the L2 ID in the received direct link request message. The link reserves a larger (or smaller) L2 ID. In this embodiment, the direct link request message sent from the second communication device to the first communication device has a larger (or smaller) random number. Therefore, the first communication device sends a direct link acceptance message to the second communication device via relay 2.

[0102] Figure 7 A schematic diagram of a process according to an embodiment of the present disclosure is shown. Figure 7 In the present embodiment, the first communication device and the second communication device may need to establish a PC5 link with each other. Figure 7 The process shown includes the following steps:

[0103] Step 701: A first communication device and a second communication device send direct link request messages to each other (per hop or end-to-end).

[0104] Step 702: If the first / second communication device has sent a direct link request message (per hop or end-to-end) to the second / first communication device before receiving a direct link request message (per hop or end-to-end) from each other, the first / second communication device determines / knows that a conflict has occurred.

[0105] Step 703: The first communication device and the second communication device stop one or more corresponding timers and wait for a specific time to initiate a new direct link request message (per hop or end-to-end). Please note that the specific time can be determined based on the implementation method. For example, the specific time can be defined as random (0~timer), that is, a random time from 0 to the timer value. In one embodiment, the timer value can be (set to) a 5G ProSe direct link management timer or a PC5 unicast link management timer. That is, the first communication device and the second communication device can wait for different times.

[0106] Figure 8A schematic diagram of a wireless terminal 80 according to an embodiment of the present disclosure is provided. The wireless terminal 80 may be a user equipment (UE), a mobile phone, a laptop computer, a tablet computer, an e-book, or a portable computer system, and is not limited thereto. The wireless terminal 80 may include a processor 800 such as a microprocessor or an application-specific integrated circuit (ASIC), a storage unit 810, and a communication unit 820. The storage unit 810 may be any data storage device that stores program code 812 accessed and executed by the processor 800. Embodiments of the storage unit 810 include, but are not limited to, a subscriber identity module (SIM), a read-only memory (ROM), a flash memory, a random access memory (RAM), a hard disk, and an optical data storage device. The communication unit 820 may be a transceiver, and is used to send and receive signals (e.g., messages or data packets) according to the processing results of the processor 800. In one embodiment, the communication unit 820 communicates with the computer via Figure 8 At least one antenna 822 is shown for transmitting and receiving signals.

[0107] In one embodiment, the storage unit 810 and the program code 812 may be omitted, and the processor 800 may include the storage unit with the stored program code.

[0108] The processor 800 may implement any one of the steps of the exemplary embodiments on the wireless terminal 80 , for example, by executing the program code 812 .

[0109] The communication unit 820 may be a transceiver. As an alternative or in addition, the communication unit 820 may combine a transmitting unit and a receiving unit configured to transmit and receive signals to and from a wireless network node (eg, a base station), respectively.

[0110] Fig. 9A schematic diagram of a radio network node 90 according to an embodiment of the present disclosure is provided. The radio network node 90 may be a satellite, a base station (BS), a network entity, a mobility management entity (MME), a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), a radio access network (RAN) node, a next generation RAN (NG-RAN) node, a gNB, an eNB, a gNB central unit (gNB CU), a gNB distributed unit (gNB-DU), a data network, a core network, or a radio network controller (RNC), and is not limited thereto. In addition, the radio network node 90 may include (execute) at least one network function such as an access and mobility management function (AMF), a session management function (SMF), a user location function (UPF), a policy control function (PCF), an application function (AF), etc. The radio network node 90 may include a processor 900 such as a microprocessor or an ASIC, a storage unit 910, and a communication unit 920. The storage unit 910 may be any data storage device that stores a program code 912 accessed and executed by the processor 900. Examples of the storage unit 910 include, but are not limited to, a SIM, a ROM, a flash memory, a RAM, a hard disk, and an optical data storage device. The communication unit 920 may be a transceiver and is used to send and receive signals (eg, messages or data packets) according to the processing results of the processor 900. In one example, the communication unit 920 transmits and receives the data packets via Fig. 9 At least one antenna 922 is shown in the figure for transmitting and receiving signals.

[0111] In one embodiment, the storage unit 910 and the program code 912 may be omitted. The processor 900 may include a storage unit with stored program code.

[0112] The processor 900 may implement any of the steps described in the exemplary embodiments on the radio network node 90 , for example by executing the program code 912 .

[0113] The communication unit 920 may be a transceiver. As an alternative or in addition, the communication unit 920 may combine a transmitting unit and a receiving unit configured to transmit and receive signals to and from a wireless terminal (eg, a user equipment or another wireless network node), respectively.

[0114] Fig.10 A flow chart of a method according to an embodiment of the present disclosure is shown. Fig.10 The method shown may be used in a first wireless terminal (e.g., UE or communication device) and comprises the following steps:

[0115] Step 1001: Determine a relay terminal that communicates with a second wireless terminal.

[0116] Step 1002: Send relay information associated with the relay terminal to the second wireless terminal.

[0117] exist Fig.10 In the present invention, the first wireless terminal determines / selects a relay terminal (eg, UE) for communicating with a second wireless terminal (eg, UE), and sends relay information associated with the relay terminal to the second wireless terminal to establish a PC5 link with the second wireless terminal.

[0118] In one embodiment, the relay information may include an L2 ID of the relay terminal.

[0119] In one embodiment, if it is determined that at least one relay selection trigger condition or at least one relay reselection trigger condition is satisfied / completed, the first wireless terminal determines / selects a relay terminal.

[0120] Fig.11 A flow chart of a method according to an embodiment of the present disclosure is shown. Fig.11 The method shown may be used for a second wireless terminal (e.g., UE or communication device) and includes the following steps:

[0121] Step 1101: Receive relay information associated with a relay terminal from a first wireless terminal.

[0122] Step 1102: Based on the relay information, establish a PC5 link with the first wireless terminal via the relay terminal.

[0123] exist Fig.11 In the present invention, the second wireless terminal receives relay information associated with the relay terminal (eg, UE) from the first wireless terminal (eg, UE). Based on the relay information, the second wireless terminal establishes an independent PC5 (eg, end-to-end) link with the first wireless terminal.

[0124] In one embodiment, the relay information may include an L2 ID of the relay terminal.

[0125] Fig.12 A flow chart of a method according to an embodiment of the present disclosure is shown. Fig.12 The method shown in can be used for a third wireless terminal (e.g., UE or communication device), and includes the following steps:

[0126] Step 1201: Send a first PC5 link establishment request to a fourth wireless terminal via a first relay terminal, wherein the first PC5 link establishment request includes first relay selection information.

[0127] exist Fig.12In the embodiment, the third wireless terminal sends a first PC5 link establishment request to the fourth wireless terminal (e.g., UE) via the first relay terminal (e.g., UE). In this embodiment, the first PC5 link establishment request includes first relay selection information, which is used for relay selection if a conflict of PC5 link establishment requests occurs.

[0128] In one embodiment, the third wireless terminal may receive a second PC5 link establishment request via the second relay terminal, wherein the second PC5 link establishment request includes second relay selection information. In this embodiment, the third wireless terminal may determine that a conflict has occurred. For example, in the following case, the third wireless terminal determines that a conflict has occurred:

[0129] - before receiving the second PC5 link establishment request, sending the first PC5 link establishment request, or

[0130] - receiving a second PC5 link establishment request within a period of time after sending the first PC5 link establishment request, or

[0131] - before receiving a response to the first PC5 link establishment request, receiving a second PC5 link establishment request.

[0132] In one embodiment, the third wireless terminal selects one of the first relay terminal or the second relay terminal based on the first relay selection information and the second relay selection information, and establishes a PC5 link with the fourth wireless terminal via the selected relay terminal.

[0133] In one embodiment, the relay selection information includes a round trip delay. For example, the first relay selection information includes a first round trip delay of a first PC5 link from the third wireless terminal via the first relay terminal to the fourth wireless terminal, and wherein the second relay selection information includes a second round trip delay of a second PC5 link from the fourth wireless terminal via the first relay terminal to the third wireless terminal.

[0134] In one embodiment, a relay corresponding to a smaller round trip delay may be selected. As an alternative, a relay corresponding to a larger round trip delay may be selected.

[0135] In one embodiment, the relay selection information includes, for example, a timestamp associated with the transmission of a PC5 link establishment request. For example, the first relay selection information includes a first timestamp associated with the first PC5 link establishment request, and the second relay selection information includes a second timestamp associated with the second PC5 link establishment request.

[0136] In one embodiment, the relay terminal corresponding to (the PC5 link establishment request) with an earlier timestamp is selected. As an alternative, the relay terminal corresponding to (the PC5 link establishment request) with a later timestamp is selected.

[0137] In one embodiment, the relay selection information includes a random number. For example, the first relay selection information includes a first random number associated with the first PC5 link establishment request, and the second relay selection information includes a second random number associated with the second PC5 link establishment request.

[0138] In one embodiment, a relay terminal corresponding to (a PC5 link establishment request) with a larger random number is selected. As an alternative, a relay terminal corresponding to (a PC5 link establishment request) with a smaller random number is selected.

[0139] In one embodiment, the relay selection information includes the L2 ID of the initial terminal. For example, the first relay selection information includes the first layer 2 identifier of the third wireless terminal, and the second relay selection information includes the second layer 2 identifier of the fourth wireless terminal.

[0140] In one embodiment, a relay terminal corresponding to (a PC5 link establishment request) with a larger L2 ID is selected. As an alternative, a relay terminal corresponding to (a PC5 link establishment request) with a smaller L2 ID is selected.

[0141] In one embodiment, the first relay terminal is selected based on the first relay selection information and the second relay selection information. In this embodiment, the third wireless terminal receives the PC5 link establishment accept message from the fourth wireless terminal via the first relay terminal.

[0142] In one embodiment, the second relay terminal is selected based on the first relay selection information and the second relay selection information. In this embodiment, the third wireless terminal sends a PC5 link establishment accept message to the fourth wireless terminal via the second relay terminal.

[0143] Fig.13 A flow chart of a method according to an embodiment of the present disclosure is shown. Fig.13 The method shown may be used for a fifth wireless terminal (eg, UE or communication device), and includes the following steps:

[0144] Step 1301: Send a first PC5 link establishment request to a sixth wireless terminal via a first relay terminal.

[0145] Step 1302: Receive a second PC5 link establishment request from a sixth wireless terminal via a second relay terminal, wherein the first link establishment request conflicts with the second link establishment request.

[0146] Step 1303: After a predefined time, initiate a seventh link establishment request to the sixth wireless terminal.

[0147] exist Fig.13 In the example, the fifth wireless terminal sends a first PC5 link establishment request to the sixth wireless terminal via the first relay terminal (for example, see Fig.10 ). In this embodiment, the fifth wireless terminal receives the second PC5 link establishment request from the sixth wireless terminal via the second relay terminal. In this embodiment, the first link establishment request conflicts with the second link establishment request. For example, the first link establishment request conflicts with the second link establishment request because:

[0148] - before receiving the second PC5 link establishment request, sending the first PC5 link establishment request, or

[0149] - receiving a second PC5 link establishment request within a period of time after sending the first PC5 link establishment request, or

[0150] - before receiving a response to the first PC5 link establishment request, receiving a second PC5 link establishment request.

[0151] In the present disclosure, the PC5 link establishment request may be replaced by a PC5-S message (eg, a PC5 link modification request). That is, the first / second PC5 link establishment request may be a PC5-S message (eg, a PC5 link modification request).

[0152] In this case, the fifth wireless terminal may wait for a predefined time before initiating another link establishment request to the sixth wireless terminal. The predefined time may be based on the implementation method. For example, the specific time may be defined as random (0~timer), that is, a random time from 0 to the timer value. In one embodiment, the timer value may be (set to) a 5G ProSe direct link management timer or a PC5 unicast link management timer. That is, the first communication device and the second communication device may wait for different times.

[0153] Although various embodiments of the present disclosure have been described above, it should be understood that they are presented only by way of example, and not by way of limitation. Similarly, various figures may depict example architectures or configurations, which are provided to enable those of ordinary skill in the art to understand the exemplary features and functions of the present disclosure. However, it should be understood by these persons that the present disclosure is not limited to the example architectures or configurations shown, but may be implemented using various alternative architectures and configurations. In addition, as will be appreciated by those of ordinary skill in the art, one or more features of an embodiment may be combined with one or more features of another embodiment described herein. Therefore, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments.

[0154] It should also be understood that any reference to an element using names such as "first," "second," etc., herein does not generally limit the number or order of those elements. Instead, these names may be used herein as a convenient means of distinguishing two or more elements or instances of an element. Thus, reference to a first element and a second element does not mean that only two elements may be employed, or that the first element must precede the second element in some manner.

[0155] In addition, it should be understood by those skilled in the art that any of a variety of different technologies and techniques may be used to represent information and signals. For example, data, instructions, commands, information, signals, bits, and symbols such as may be mentioned in the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0156] Those skilled in the art should also understand that any of the various illustrative logical blocks, units, processors, devices, circuits, methods, and functions described in conjunction with the aspects disclosed herein may be implemented by electronic hardware (e.g., digital implementations, analog implementations, or a combination of both), firmware, various forms of programs or design codes containing instructions (for convenience, may be referred to herein as "software" or "software units"), or any combination of these technologies.

[0157] In order to clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, units, circuits and steps have been generally described above with respect to their functions. Whether such functions are implemented as hardware, firmware, or as software, or as a combination of these technologies, depends on the specific application and the design constraints imposed on the entire system. Those skilled in the art can implement the described functions in various ways for each specific application, but the decision of such implementation will not lead to deviation from the scope of the present disclosure. According to various embodiments, processors, devices, components, circuits, structures, machines, units, etc. can be configured to perform one or more functions described herein. The terms "configured to" or "configured for" used herein with respect to a specified operation or function refer to a processor, device, component, circuit, structure, machine, unit, etc., which is physically constructed, programmed and / or arranged to perform a specified operation or function.

[0158] In addition, it should be understood by those skilled in the art that the various illustrative logic blocks, units, devices, components and circuits described herein may be implemented in or performed by an integrated circuit (IC), which may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device or any combination thereof. The logic blocks, units and circuits may also include antennas and / or transceivers to communicate with various components within a network or within a device. The general-purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other suitable configuration for performing the functions described herein. If implemented in software, the functions may be stored as one or more instructions or codes on a computer-readable medium. Therefore, the steps of the method or algorithm disclosed herein may be implemented as software stored on a computer-readable medium.

[0159] Computer-readable media include computer storage media and communication media, including any medium capable of transferring a computer program or code from one place to another. The storage medium can be any available medium that a computer can access. As an example and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to store desired program code in the form of instructions or data structures and can be accessed by a computer.

[0160] In this application, the term "unit" used herein refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. In addition, for the purpose of discussion, various units are described as discrete units; however, it is obvious to those of ordinary skill in the art that two or more units can be combined to form a single unit that performs the associated functions according to the embodiments of the present disclosure.

[0161] In addition, memory or other memory and communication components may be used in embodiments of the present disclosure. It should be understood that, for the sake of clarity, the above description has described embodiments of the present disclosure with reference to different functional units and processors. However, it is apparent that any suitable functional distribution between different functional units, processing logic elements or domains may be used without departing from the present disclosure. For example, functions illustrated as being performed by separate processing logic elements or controllers may be performed by the same processing logic elements or controllers. Therefore, reference to a specific functional unit is only a reference to a suitable means for providing the described functions, rather than an indication of a strict logical or physical structure or organization.

[0162] Various modifications to the embodiments described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the scope of the claims. Therefore, the present disclosure is not intended to be limited to the embodiments shown herein, but should be consistent with the broadest scope consistent with the novel features and principles disclosed herein, as described in the following claims.

Claims

1. A wireless communication method for use in a third wireless terminal, the method comprising: sending a first PC5 link establishment request to the fourth wireless terminal via the first relay terminal, wherein the first PC5 link establishment request includes first relay selection information, receiving a second PC5 link establishment request from the fourth wireless terminal via the second relay terminal, wherein the second PC5 link establishment request includes second relay selection information, selecting one of the first relay terminal or the second relay terminal based on the first relay selection information and the second relay selection information, and A PC5 link is established with the fourth wireless terminal via the selected relay terminal.

2. The wireless communication method according to claim 1, wherein: The first relay selection information includes a first round trip delay of the first PC5 link from the third wireless terminal to the fourth wireless terminal via the first relay terminal, and The second relay selection information includes a second round-trip delay of a second PC5 link from the fourth wireless terminal to the third wireless terminal via the first relay terminal.

3. The wireless communication method according to claim 1 or 2, wherein: The first relay selection information includes a first timestamp associated with the first PC5 link establishment request, and The second relay selection information includes a second timestamp associated with the second PC5 link establishment request.

4. The wireless communication method according to any one of claims 1 to 3, wherein: The first relay selection information includes a first random number associated with the first PC5 link establishment request, and The second relay selection information includes a second random number associated with the second PC5 link establishment request.

5. The wireless communication method according to any one of claims 1 to 4, wherein: The first relay selection information includes a first layer 2 identifier of the third wireless terminal, and The second relay selection information includes the second layer 2 identifier of the fourth wireless terminal.

6. The wireless communication method according to any one of claims 1 to 5, wherein: selecting the second relay terminal based on the first relay selection information and the second relay selection information, and Wherein, establishing a PC5 link with the fourth wireless terminal via the selected relay terminal includes: Send a PC5 link establishment acceptance message to the fourth wireless terminal via the second relay terminal.

7. The wireless communication method according to any one of claims 1 to 6, wherein: selecting the first relay terminal based on the first relay selection information and the second relay selection information, and Wherein, establishing a PC5 link with the fourth wireless terminal via the selected relay terminal includes: A PC5 link establishment accept message is received from the fourth wireless terminal via the first relay terminal.

8. A wireless communication method for use in a fifth wireless terminal, the method comprising: Sending a first PC5 link establishment request to the sixth wireless terminal via the first relay terminal, receiving a second PC5 link establishment request from the sixth wireless terminal via a second relay terminal, wherein the first link establishment request conflicts with the second link establishment request, and After a predefined time, a seventh link establishment request for the sixth wireless terminal is initiated.

9. A wireless communication method for use in a first wireless terminal, the method comprising: determining a relay terminal for communicating with the second wireless terminal, and Relay information associated with the relay terminal is sent to the second wireless terminal.

10. The wireless communication method according to claim 9, further comprising: It is determined that at least one relay selection trigger condition is satisfied.

11. The wireless communication method according to claim 9 or 10, wherein: The relay information includes a layer 2 identifier of the relay terminal.

12. A wireless communication method for use in a second wireless terminal, the method comprising: receiving relay information associated with the relay terminal from the first wireless terminal, and Based on the relay information, a PC5 link with the first wireless terminal is established via the relay terminal.

13. The wireless communication method according to claim 12, wherein: The relay information includes a layer 2 identifier of the relay terminal.

14. A first wireless terminal, comprising: a processor configured to determine a relay terminal for communicating with a second wireless terminal, and A communication unit is configured to send relay information associated with the relay terminal to the second wireless terminal.

15. The first wireless terminal according to claim 14, wherein: The processor is further configured to execute the wireless communication method according to claim 10 or 11.

16. A second wireless terminal, comprising: a communication unit configured to receive relay information associated with a relay terminal from a first wireless terminal, and A processor is configured to establish a PC5 link with the first wireless terminal via the relay terminal based on the relay information.

17. The second wireless terminal according to claim 16, wherein: The processor is further configured to execute the wireless communication method according to claim 13.

18. A third wireless terminal, comprising: A communication unit, wherein the communication unit is configured to: sending a first PC5 link establishment request to a fourth wireless terminal via the first relay terminal, wherein the first PC5 link establishment request includes first relay selection information, and receiving a second PC5 link establishment request from the fourth wireless terminal via the second relay terminal, wherein the second PC5 link establishment request includes second relay selection information, and A processor, the processor being configured to: selecting one of the first relay terminal or the second relay terminal based on the first relay selection information and the second relay selection information, and A PC5 link is established with the fourth wireless terminal via the selected relay terminal.

19. The third wireless terminal according to claim 18, wherein: The processor is further configured to execute the wireless communication method according to any one of claims 2 to 7.

20. A fifth wireless terminal, comprising: A communication unit, wherein the communication unit is configured to: Sending a first PC5 link establishment request to the sixth wireless terminal via the first relay terminal, receiving a second PC5 link establishment request from the sixth wireless terminal via a second relay terminal, wherein the first link establishment request conflicts with the second link establishment request, and A processor is configured to initiate a seventh link establishment request for the sixth wireless terminal after a predefined time.

21. A computer program product comprising computer-readable program medium code stored thereon, which, when executed by a processor, causes the processor to implement the wireless communication method according to any one of claims 1 to 13.

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