Communication method and device

Abstract

The present application relates to the field of communication technology and discloses a communication method and apparatus. The method includes: a first terminal device determines a candidate relay device, wherein the candidate relay device includes at least one relay device; and a first message is sent to the second terminal device, wherein the first message is used to request a replacement of the relay device, and the first message includes an identifier of the candidate relay device. Using the above method, the first terminal device can determine the candidate relay device and send the first message to the second terminal device, so that the second terminal device can determine the second relay device from the candidate relay devices according to the first message, thereby achieving the replacement of the relay device between the first terminal device and the second terminal device from the first relay device to the second relay device.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to a communication method and device. Background Art

[0002] With the development of communication technology, since the 3rd Generation Partnership Project (3 rd Generation Partnership Project, 3GPP) version (release) 12, the fourth generation (4 th 4G (4th generation) communication systems can support device-to-device communication, a type of communication known as device-to-device (D2D). Unlike traditional cellular communication technologies, D2D allows direct communication between devices.

[0003] D2D communication includes one-to-many communication and one-to-one communication. One-to-many communication corresponds to multicast and broadcast communication, while one-to-one communication corresponds to unicast communication. In one-to-one communication, if the sending and receiving terminal devices are within close range, they can communicate directly after discovering each other. If the sending and receiving terminal devices are farther apart, they can communicate through a relay device, thereby extending the communication distance between the terminal devices.

[0004] However, after the sending terminal device and the receiving terminal device select a relay device (eg, a first relay device) for communication, how to change the relay device (eg, from the first relay device to the second relay device) still requires further study. Summary of the Invention

[0005] The present application provides a communication method and apparatus for replacing a relay device between a first device and a second device.

[0006] In a first aspect, an embodiment of the present application provides a communication method, which can be applied to a first terminal device or a chip in the first terminal device, wherein relay communication is performed between the first terminal device and the second terminal device through a first relay device; taking the application of this method to the first terminal device as an example, in this method, the first terminal device determines a candidate relay device, and the candidate relay device includes at least one relay device; and sends a first message to the second terminal device, wherein the first message is used to request replacement of the relay device, and the first message includes an identifier of the candidate relay device.

[0007] Using the above method, the first terminal device can determine the candidate relay device and send a first message to the second terminal device, so that the second terminal device can determine the second relay device from the candidate relay devices based on the first message, thereby realizing the replacement of the relay device between the first terminal device and the second terminal device from the first relay device to the second relay device.

[0008] In one possible design, sending the first message to the second terminal device includes: sending the first message to the second terminal device through the first relay device.

[0009] In one possible design, the first message also includes: the signal status between the candidate relay device and the first terminal device, and / or the address of the candidate relay device.

[0010] In one possible design, determining the candidate relay device includes: determining that the candidate relay device includes the third terminal device based on a signal status between the third terminal device and the first terminal device; wherein the signal status includes signal quality and / or signal strength.

[0011] In one possible design, determining that the candidate relay devices include the third terminal device based on the signal status between the third terminal device and the first terminal device includes: determining that the candidate relay devices include the third terminal device based on the signal status between the third terminal device and the first terminal device, and the signal status between the first relay device and the first terminal device; or determining that the candidate relay devices include the third terminal device based on the signal status between the third terminal device and the first terminal device, the signal status between the first relay device and the first terminal device, and the communication link status between the third terminal device and the second terminal device; wherein the communication link status includes the existence of a communication link or the absence of a communication link.

[0012] In one possible design, the method further includes: obtaining a signal status between the third terminal device and the first terminal device.

[0013] In one possible design, obtaining the signal status between the third terminal device and the first terminal device includes: sending a third message, where the third message is used to discover a relay device; receiving a fourth message from the third terminal device, where the fourth message is used to respond to the third message; and determining the signal status between the third terminal device and the first terminal device based on the fourth message.

[0014] In one possible design, obtaining the signal status between the third terminal device and the first terminal device includes: receiving a fifth message from the third terminal device, the fifth message being used to indicate that the third terminal device supports relay communication; and determining the signal status between the third terminal device and the first terminal device based on the fifth message.

[0015] In one possible design, the method further includes: obtaining a communication link status between the third terminal device and the second terminal device.

[0016] In one possible design, obtaining the communication link status between the third terminal device and the second terminal device includes: receiving a fifth message from the third terminal device, the fifth message including an identifier of the second terminal device, the fifth message being used to indicate that the third terminal device supports relay communication and that a communication link exists between the third terminal device and the second terminal device; and, based on the fifth message, determining the communication link status between the third terminal device and the second terminal device.

[0017] In the second aspect, an embodiment of the present application provides a communication method, which can be applied to a third terminal device or a chip in a third terminal device. Taking the application of this method to a third terminal device as an example, in this method, the third terminal device obtains the identification of at least one terminal device that has a communication link with the third terminal device, and sends a fifth message, wherein the fifth message includes the identification of the at least one terminal device, and the fifth message is used to indicate that the third terminal device supports relay communication and that there is a communication link between the third terminal device and the at least one terminal device.

[0018] In a third aspect, an embodiment of the present application provides a communication method, which can be applied to a second terminal device or a chip in the second terminal device, wherein relay communication is performed between the second terminal device and the first terminal device through a first relay device; taking the application of this method to the second terminal device as an example, in this method, the second terminal device receives a first message from the first terminal device, the first message is used to request replacement of the relay device, the first message includes an identification of a candidate relay device, and the candidate relay device includes at least one relay device; and, according to the first message, an indication information is sent to the first terminal device, the indication information is used to indicate that the relay device between the second terminal device and the first terminal device is replaced with the second relay device, and the candidate relay device includes the second relay device.

[0019] Using the above method, the second terminal device receives the first message from the first terminal device and can determine the second relay device from the candidate relay devices based on the first message, thereby replacing the relay device between the first and second terminal devices from the first relay device to the second relay device. Moreover, in this method, because the first message includes the identifier of the candidate relay device, the second terminal device can directly learn which devices are candidate relay devices. In this way, from the perspective of the relay device, the relay device can effectively avoid forwarding broadcast messages, thereby effectively saving resources. From the perspective of the second terminal device, there is no need to receive broadcast messages from the relay device to identify which devices are candidate relay devices, which can effectively reduce the processing burden of the second terminal device.

[0020] In one possible design, the candidate relay devices include at least two relay devices, and the method further includes: determining the second relay device based on a signal status between the at least two relay devices and the second terminal device.

[0021] In one possible design, the sending of indication information to the first terminal device includes: sending the indication information to the first terminal device based on the signal status between the second relay device and the second terminal device, and the signal status between the first relay device and the second terminal device.

[0022] By adopting this method, indication information can be sent to the first terminal device only when the signal status between the second relay device and the second terminal device is better than the signal status between the first relay device and the second terminal device, so as to ensure that the transmission performance of the replaced relay device is better than the transmission performance of the original relay device.

[0023] In one possible design, the candidate relay device includes at least two relay devices, and the first message also includes the signal status between the candidate relay device and the first terminal device; the method also includes: determining the second relay device based on the signal status between the candidate relay device and the first terminal device, and the signal status between the candidate relay device and the second terminal device.

[0024] In this way, the second terminal device comprehensively considers the signal status between the candidate relay device and the first terminal device, as well as the signal status between the candidate relay device and the second terminal device, to select the second relay device, so that the relay transmission performance of the selected second relay device is better.

[0025] In one possible design, the method further includes: obtaining a signal status between the candidate relay device and the second terminal device.

[0026] In one possible design, obtaining the signal status between the candidate relay device and the second terminal device includes: broadcasting a request message, the request message including the identifier of a first candidate relay device, the first candidate relay device being any one of the candidate relay devices; receiving a response message from the first candidate relay device; and determining the signal status between the first candidate relay device and the second terminal device based on the response message.

[0027] In one possible design, the first message also includes the address of the candidate relay device; obtaining the signal status between the candidate relay device and the second terminal device includes: sending a request message to the second candidate relay device according to the address of the second candidate relay device, where the second candidate relay device is any one of the candidate relay devices; receiving a response message from the second candidate relay device; and determining the signal status between the second candidate relay device and the second terminal device according to the response message.

[0028] In one possible design, obtaining the signal status between the candidate relay device and the second terminal device includes: receiving a fifth message from a third candidate relay device, the fifth message being used to indicate that the third candidate relay device supports relay communication, the third candidate relay device being any one of the candidate relay devices; and determining the signal status between the third candidate relay device and the second terminal device based on the fifth message.

[0029] It should be noted that the methods described in the first, second and third aspects above correspond to each other, and the beneficial effects of the relevant technical features in the methods described in each aspect can be referenced to each other, and the details will not be repeated here.

[0030] In a fourth aspect, an embodiment of the present application provides a communication method, which can be applied to a first terminal device or a chip in the first terminal device, wherein relay communication is performed between the first terminal device and the second terminal device through a first relay device; taking the application of this method to the first terminal device as an example, in this method, the first terminal device obtains the communication status between the first terminal device and the first relay device; and, based on the communication status, sends a sixth message, wherein the sixth message is used to request replacement of the relay device.

[0031] Using this method, the first terminal device can broadcast the sixth message according to the communication status, thereby triggering the candidate relay device to send the seventh message to the second terminal device, so that the second terminal device can determine the second relay device from the candidate relay devices, thereby realizing the replacement of the relay device between the first terminal device and the second terminal device from the first relay device to the second relay device.

[0032] In one possible design, the sixth message includes a relay reselection indication, where the relay reselection indication is used to indicate the replacement of the relay device.

[0033] In one possible design, the sixth message includes signal status requirements and / or quality of service QoS requirements.

[0034] In one possible design, the method includes: determining the signal status requirement based on the signal status between the first terminal device and the first relay device; and / or determining the QoS requirement based on the QoS that can be met by the communication link between the first terminal device and the first relay device.

[0035] In one possible design, sending the sixth message according to the communication status includes: sending the sixth message after determining that the signal status between the first terminal device and the first relay device does not meet the preset conditions; or sending the sixth message according to the QoS that can be met by the communication link between the first terminal device and the first relay device, and the QoS requirements of the communication service between the first terminal device and the second terminal device; or sending the sixth message according to the signal status between the first terminal device and the first relay device, the preset conditions, the QoS that can be met by the communication link between the first terminal device and the first relay device, and the QoS requirements of the communication service between the first terminal device and the second terminal device.

[0036] In one possible design, the method also includes: receiving first indication information from the second terminal device through a second relay device, the first indication information being used to indicate that the relay device between the second terminal device and the first terminal device is replaced with the second relay device; or, receiving second indication information from the second terminal device through the first relay device, the second indication information being used to indicate that the relay device between the second terminal device and the first terminal device is replaced with the second relay device.

[0037] In a fifth aspect, an embodiment of the present application provides a communication method, which can be applied to a first candidate relay device or a chip in the first candidate relay device. Taking the application of the method to the first candidate relay device as an example, in the method, the first candidate relay device receives a sixth message from the first terminal device, and the sixth message is used to request to replace the relay device; and, based on the sixth message, a seventh message is sent, and the seventh message includes the signal status between the first candidate relay device and the first terminal device.

[0038] In one possible design, the sixth message includes a relay reselection indication, which is used to indicate the replacement of the relay device; sending the seventh message according to the sixth message includes: according to the relay reselection indication, carrying the signal status between the first candidate relay device and the first terminal device in the seventh message; and sending the seventh message.

[0039] In one possible design, the sixth message includes signal status requirements and / or QoS requirements; sending the seventh message based on the sixth message includes: sending the seventh message when the signal status between the first candidate relay device and the first terminal device meets the signal status requirements in the sixth message; or, sending the seventh message when the QoS corresponding to the signal status between the first candidate relay device and the first terminal device meets the QoS requirements in the sixth message; or, sending the seventh message when the signal status between the first candidate relay device and the first terminal device meets the signal status requirements in the sixth message, and the QoS corresponding to the signal status between the first candidate relay device and the first terminal device meets the QoS requirements in the sixth message.

[0040] Using this method, since the sixth message includes signal status requirements and / or QoS requirements, the terminal device that receives the sixth message can send the seventh message when the signal status requirements and / or QoS requirements are met, and may not send the seventh message when the signal status requirements and / or QoS requirements are not met. This can avoid some terminal devices that are not suitable as candidate relay devices from sending the seventh message, effectively reducing signaling overhead.

[0041] In one possible design, the method also includes: receiving indication information from the second terminal device; sending the indication information to the first terminal device; wherein the indication information is used to indicate that the relay device between the second terminal device and the first terminal device is replaced with the first candidate relay device.

[0042] In the sixth aspect, an embodiment of the present application provides a communication method, which can be applied to a second terminal device or a chip in the second terminal device, wherein relay communication is performed between the second terminal device and the first terminal device through a first relay device; taking the application of this method to the second terminal device as an example, in this method, the second terminal device receives a seventh message from a candidate relay device, and the seventh message includes the signal status between the candidate relay device and the first terminal device; and, based on the signal status between the candidate relay device and the first terminal device and the signal status between the candidate relay device and the second terminal device, an indication information is sent to the first terminal device; wherein the indication information is used to indicate that the relay device between the first terminal device and the second terminal device is replaced with a second relay device, and the candidate relay device includes the second relay device.

[0043] In one possible design, the candidate relay devices include at least two relay devices.

[0044] In one possible design, the candidate relay device also includes the first relay device.

[0045] In one possible design, the sending of indication information to the first terminal device includes: sending the indication information to the first terminal device through the second relay device; or, sending the indication information to the first terminal device through the first relay device.

[0046] It should be noted that the methods described in the fourth, fifth and sixth aspects above correspond to each other, and the beneficial effects of the relevant technical features in the methods described in each aspect can be referenced to each other, and the details will not be repeated here.

[0047] In the seventh aspect, an embodiment of the present application provides a communication device, which may be a terminal device (such as the first terminal device in the first aspect, the third terminal device in the second aspect, the second terminal device in the third aspect, the first terminal device in the fourth aspect, the first candidate relay device in the fifth aspect, the second terminal device in the sixth aspect) or a chip arranged inside the terminal device. The communication device has the function of implementing any one of the above-mentioned first to sixth aspects. For example, the communication device includes a module or unit or means corresponding to the steps involved in any one of the above-mentioned first to sixth aspects. The function or unit or means may be implemented by software, or by hardware, or the corresponding software implementation may be executed by hardware.

[0048] In one possible design, the communication device includes a processing unit and a communication unit, wherein the communication unit can be used to send and receive signals to achieve communication between the communication device and other devices, for example, the communication unit is used to receive configuration information from a terminal device; the processing unit can be used to perform some internal operations of the communication device.

[0049] In another possible design, the communication device includes a processor and may also include a transceiver, the transceiver is used to send and receive signals, and the processor executes program instructions to complete the method in any possible design or implementation of the first to sixth aspects above. The communication device may also include one or more memories, the memory is used to couple with the processor, and the memory can store the necessary computer programs or instructions for implementing the functions involved in any of the first to sixth aspects above. The processor can execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the first to sixth aspects above.

[0050] In another possible design, the communication device includes a processor, which can be coupled to a memory. The memory can store the necessary computer programs or instructions for implementing the functions of any of the first to sixth aspects. The processor can execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the method of any possible design or implementation of the first to sixth aspects.

[0051] In another possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method in any possible design or implementation of the first to sixth aspects above.

[0052] It can be understood that in the seventh aspect above, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor, which is implemented by reading the software code stored in the memory. In addition, the above processors can be one or more, and the memories can be one or more. The memory can be integrated with the processor, or the memory and the processor can be set separately. In the specific implementation process, the memory can be integrated with the processor on the same chip, or can be set on different chips respectively. The embodiment of the present application does not limit the type of memory and the setting method of the memory and the processor.

[0053] In an eighth aspect, an embodiment of the present application provides a communication system, which includes the first terminal device in the first aspect, the third terminal device in the second aspect, and the second terminal device in the third aspect.

[0054] In the ninth aspect, an embodiment of the present application provides a communication system, which includes the first terminal device in the fourth aspect, the first candidate relay device in the fifth aspect, and the second terminal device in the sixth aspect.

[0055] In the tenth aspect, the present application provides a computer-readable storage medium, which stores computer-readable instructions. When a computer reads and executes the computer-readable instructions, the computer executes the method in any possible design of the first to sixth aspects above.

[0056] In an eleventh aspect, the present application provides a computer program product, which, when read and executed by a computer, enables the computer to execute the method in any possible design of the first to sixth aspects above.

[0057] In the twelfth aspect, the present application provides a chip, which includes a processor, and the processor is coupled to a memory, and is used to read and execute a software program stored in the memory to implement the method in any possible design of the first to sixth aspects above.

[0058] These and other aspects of the present application will become more readily apparent from the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A schematic diagram of a network architecture applicable to an embodiment of the present application;

[0060] Figure 2 A flowchart for discovering and selecting relay devices;

[0061] Figure 3 Schematic diagram of the process of establishing a PC5 connection;

[0062] Figure 4 This is a flow chart corresponding to the communication method provided in Example 1 of the present application;

[0063] Figure 5 This is a flow chart corresponding to the communication method provided in Example 2 of the present application;

[0064] Figure 6 This is a flow chart corresponding to the communication method provided in Example 3 of the present application;

[0065] Figure 7 A possible exemplary block diagram of the apparatus involved in the embodiments of the present application;

[0066] Figure 8 A schematic diagram of the structure of a terminal device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0067] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0068] Figure 1 This is a schematic diagram of a network architecture applicable to the embodiment of this application. Figure 1 As shown, the network architecture may include one or more terminal devices (such as terminal device 1021 and terminal device 1022) and one or more relay devices (such as relay device 101). The terminal device 1021 and the terminal device 1022 can communicate with each other, that is, device-to-device (D2D) communication.

[0069] For example, terminal device 1021 can send data to terminal device 1022. In this case, terminal device 1021 can be called a sending terminal device or a source terminal device, and terminal device 1022 can be called a receiving terminal device or a target terminal device. For another example, terminal device 1022 can send data to terminal device 1021. In this case, terminal device 1022 can be called a sending terminal device or a source terminal device, and terminal device 1021 can be called a receiving terminal device or a target terminal device.

[0070] Furthermore, when the terminal device 1021 and the terminal device 1022 are within a close range, they can communicate directly after discovering each other. For example, the terminal device 1021 and the terminal device 1022 can establish a connection based on the near field communication 5 (proximity communication 5, PC5) interface, and then communicate through the connection, where the connection can be called a PC5 connection or a PC5 link or a PC5 communication link. When the terminal device 1021 and the terminal device 1022 are far apart, they can communicate through a relay device (such as relay device 101), that is, a first connection can be established between the terminal device 1021 and the relay device 101 based on the PC5 interface, and a second connection can be established between the relay device 101 and the terminal device 1022 based on the PC5 interface, and then the terminal device 1021 and the terminal device 1022 communicate through the first connection and the second connection. For example, the relay device 101 can forward the data received from the terminal device 1021 to the terminal device 1022, and forward the data received from the terminal device 1022 to the terminal device 1021.

[0071] It should be understood that the embodiments of the present application do not limit the number of terminal devices and relay devices in the network architecture; and in addition to terminal devices and relay devices, the above-mentioned network architecture may also include other devices, such as access network device 103, and terminal device 1021 or terminal device 1022 may also communicate with access network device 103 through the air interface, which is not limited by the embodiments of the present application.

[0072] The following is a detailed description of the terminal equipment, relay equipment, and access network equipment.

[0073] 1. Terminal Equipment

[0074] Terminal devices, also known as user equipment (UE), include devices that provide voice and / or data connectivity to users. For example, they may include handheld devices with wireless connectivity or processing devices connected to a wireless modem. The terminal device can communicate with the core network via a radio access network (RAN) and exchange voice and / or data with the RAN. The terminal device may include a wireless terminal device, a mobile terminal device, a device-to-device (D2D) terminal device, a vehicle-to-everything (V2X) terminal device, a machine-to-machine / machine-type communication (M2M / MTC) terminal device, an Internet of Things (IoT) terminal device, a subscriber unit, a subscriber station, a mobile station, a remote station, an access point (AP), a remote terminal, an access terminal, a user terminal, a user agent, or user equipment. For example, it may include a mobile phone (also known as a "cellular" phone), a computer with a mobile terminal device, a portable, pocket-sized, handheld, or computer-integrated mobile device, etc. Examples include personal communication service (PCS) phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), and other devices. Also included are limited devices, such as those with low power consumption, limited storage capacity, or limited computing power. Examples include information sensing devices such as barcode scanners, radio frequency identification (RFID), sensors, global positioning systems (GPS), and laser scanners.

[0075] In the embodiments of the present application, the device for realizing the function of the terminal device can be a terminal device, or a device that can support the terminal device to realize the function, such as a chip system or a combination device or component that can realize the function of the terminal device, and the device can be installed in the terminal device. In the embodiments of the present application, the chip system can be composed of chips, or it can include chips and other discrete devices. In the technical solutions provided in the embodiments of the present application, the device for realizing the function of the terminal device is described as an example of a terminal device.

[0076] 2. Relay Equipment

[0077] A relay device may refer to a terminal device or other possible device that supports relay communication (i.e., supports forwarding communication data between a source terminal device and a target terminal device), without specific limitation. It should be noted that the relay device in the embodiments of the present application is a relay device between terminal devices, as distinguished from a relay device between a terminal device and an access network device.

[0078] In the embodiments of the present application, the apparatus for implementing the functions of a relay device may be a relay device, or may be an apparatus capable of supporting the relay device in implementing the functions, such as a chip system or a combination device or component capable of implementing the functions of a relay device, and the apparatus may be installed in the relay device. In the technical solutions provided in the embodiments of the present application, the apparatus for implementing the functions of a relay device is described as an example in which the apparatus is a relay device.

[0079] 3. Access Network Equipment

[0080] Access network equipment is a node or device that connects terminal devices to a wireless network. Access network equipment can also be called a base station. Examples of access network equipment include, but are not limited to, the following: a new generation Node B (gNB), an evolved Node B (eNB), a radio network controller (RNC), a Node B (NB), a base station controller (BSC), a base transceiver station (BTS), a home evolved node B (HeNB) or home node B (HNB), a baseband unit (BBU), a transmitting and receiving point (TRP), a transmitting point (TP), or a mobile switching center in a 5G communication system.

[0081] above Figure 1The network architecture shown can be applicable to communication systems of various radio access technologies (RAT), for example, a 4G (or long term evolution (LTE)) communication system, a 5G (or new radio (NR)) communication system, and of course a future communication system. The network architecture and service scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. It is known to those skilled in the art that with the evolution of the communication network architecture and the emergence of new service scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0082] In the above Figure 1 In the illustrated network architecture, two terminal devices can communicate via a relay device. Specifically, the two terminal devices can first discover and select a relay device, and then establish a PC5 connection with the selected relay device.

[0083] The following describes the implementation of discovering and selecting a relay device. Figure 2 For a flow chart of discovering and selecting relay devices, see Figure 2 As shown, the process may include:

[0084] S200. After the terminal device successfully registers in the core network, the core network can authorize the service of the terminal device. For example, the core network authorizes the terminal device to communicate through relay, and then the terminal device can be used as a sending terminal device or a receiving terminal device. For another example, the core network authorizes the terminal device to support relay communication, and then the terminal device can be used as a relay device.

[0085] S201 , the source terminal device sends a request message 1 , which may include an identifier of the target terminal device and relay indication information (relay_indication=1).

[0086] Here, when terminal device 1 determines that it needs to communicate with terminal device 2 through a relay device, terminal device 1 can act as the source terminal device and use terminal device 2 as the target terminal device to send request message 1. The request message 1 can be sent via broadcast, and the identifier of the target terminal device included in the request message 1 can be the application layer identifier of the target terminal device. The relay indication information is used to indicate the number of relay devices that need to be selected between the source terminal device and the target terminal device. For example, if relay_indication=1, it means that one relay device needs to be selected between the source terminal device and the target terminal device.

[0087] S202, other terminal devices around the source terminal device (such as relay device 1) can receive request message 1 and send request message 2 according to request message 1. Request message 2 may include the identifier of the target terminal device and relay indication information (relay_indication=0).

[0088] S203, other terminal devices around the source terminal device (such as relay device 2) can receive request message 1 and send request message 2 according to request message 1. Request message 2 may include the identifier of the target terminal device and relay indication information (relay_indication=0).

[0089] Here, after receiving request message 1, other terminal devices around the source terminal device (such as relay device 1 and relay device 2) find that relay_indication in request message 1 = 1 (greater than 0) and they themselves support relay communication, they can set relay_indication to 0 and send request message 2. After receiving request message 1, other terminal devices around the source terminal device (such as terminal device 3) find that relay_indication in request message 1 = 1, but they themselves do not support relay communication, they can do nothing (such as not send request message 2).

[0090] S204 , after receiving the request message 2 sent by relay device 1 and the request message 2 sent by relay device 2 , the target terminal device may select a relay device from relay device 1 and relay device 2 , such as relay device 1 .

[0091] S205 , the target terminal device returns a response message 1 to the source terminal device through the relay device 1 .

[0092] S206: If the target terminal device also receives the request message 1 sent by the source terminal device, and finds that the identifier of the target terminal device in the request message 1 is its own identifier, it can directly return a response message 2 to the source terminal device.

[0093] S207, the source terminal device can receive response message 1 and response message 2, that is, for the source terminal device, there can be two paths for communicating with the target terminal device, namely the indirect communication path (indirect path) and the direct communication path (direct path) through relay device 1, and then the source terminal device can select a path from the indirect communication path and the direct communication path, for example, the source terminal device selects the indirect communication path.

[0094] S208 , the source terminal device communicates with the target terminal device through relay device 1 .

[0095] Here, the source terminal device may establish a PC5 connection with the relay device 1 , and the target terminal device may establish a PC5 connection with the relay device 1 , so that the source terminal device communicates with the target terminal device through the relay device 1 .

[0096] Furthermore, if the source terminal device selects a direct communication path in S205, the source terminal device can establish a PC5 connection with the target terminal device and then communicate directly with the target terminal device. Alternatively, the source terminal device can communicate directly with the target terminal device or communicate with the target terminal device through the relay device 1.

[0097] It should be noted that the above Figure 2 The request message 1 and the request message 2 involved in the above-mentioned process may be referred to as a discovery request message, a solicitation message, a direct communication request message, or other possible names; the response message 1 and the response message 2 may be referred to as a request accept message, a direct communication accept message, or other possible names, without specific limitation. Specifically, when the request message 1 and the request message 2 are discovery request messages or solicitation messages, the response message 1 and the response message 2 may be request accept messages; when the request message 1 and the request message 2 are direct communication request messages, the response message 1 and the response message 2 may be direct communication accept messages.

[0098] The following describes how to establish a PC5 connection. Figure 2 Take the relay device selected in 1) as an example to establish a connection with PC5. Figure 3 For a flow chart of establishing a PC5 connection, see Figure 3 As shown, the process may include:

[0099] S301: The source terminal device sends a request message to the relay device.

[0100] Here, the source terminal device is Figure 2The address of the relay device can be obtained in the described process. For example, the source terminal device receives the response message 1 returned by the relay device 1. The response message 1 may include the address of the relay device 1, and then the source terminal device can obtain the address of the relay device 1 according to the response message 1. Furthermore, the source terminal device can send a request message to the relay device according to the address of the relay device, wherein the request message may include the source address (i.e., the address of the source terminal device) and the destination address (i.e., the address of the relay device). It should be noted that the address involved in the embodiment of the present application may be a layer-2 identifier (layer-2 identifier) ​​or a layer-2 address.

[0101] S302: The source terminal device and the relay device establish a security context.

[0102] S303: The relay device sends a response message to the source terminal device.

[0103] Here, the response message may include a source address (ie, the address of the relay device) and a destination address (ie, the address of the source terminal device). Optionally, the source terminal device and the relay device may also negotiate and determine quality of service (QoS) parameters through the request message and the response message.

[0104] S304: The source terminal device and the relay device complete the establishment of a PC5 connection, and can then transmit data to each other. In addition, the source terminal device and the relay device can also allocate a PC5 link identifier to identify the PC5 connection.

[0105] It should be noted that the above Figure 3 The request message involved in the communication may be called a direct communication request message or a unicast establishment request message or other possible names; the response message may be called a direct communication acceptance message or a unicast establishment acceptance message or other possible names.

[0106] Considering that when the source terminal device and the target terminal device communicate through the relay device, it may be necessary to replace the relay device. Therefore, the embodiments of the present application will focus on how to replace the relay device. It should be noted that in the embodiments of the present application, replacing the relay device can also be replaced with other possible descriptions, such as reselecting the relay device (i.e., reselecting the relay device) or updating the relay device.

[0107] The embodiments of the present application are described in detail below in conjunction with Embodiment 1 and Embodiment 2.

[0108] Example 1

[0109] Figure 4 This is a flow chart corresponding to the communication method provided in Example 1 of this application, such as Figure 4As shown, the method includes:

[0110] S400: A first terminal device and a second terminal device perform relay communication via a first relay device.

[0111] Here, the first terminal device may be a source terminal device, and the second terminal device may be a target terminal device. Figure 2 The process shown selects the first relay device, and the first terminal device and the first relay device can be Figure 3 The process shown in the figure establishes a connection with PC5. The second terminal device and the first relay device can be connected through Figure 3 The process shown establishes a connection to PC5.

[0112] S401: The first terminal device determines a candidate relay device.

[0113] Here, the candidate relay device may include at least one relay device. Further, the candidate relay device may include at least one relay device other than the first relay device.

[0114] Exemplarily, there may be multiple implementations for the first terminal device to determine a candidate relay device, and several possible implementations are described below.

[0115] Implementation 1

[0116] The first terminal device sends a third message, and the third message is used to discover a relay device; wherein, the third message can be sent by broadcasting. After receiving the third message, other terminal devices around the first terminal device (such as a third terminal device) determine that they support relay communication, they can send a fourth message to the first terminal device, and the fourth message is used to respond to the third message. Furthermore, the fourth message can also be used to indicate that the third terminal device supports relay communication; in addition, if the third terminal device determines that it does not support relay communication, it can not process it (such as not feeding back the fourth message). Accordingly, the first terminal device receives the fourth message from the third terminal device, and can determine the signal status between the third terminal device and the first terminal device based on the fourth message. Exemplarily, the above-mentioned third message can be a newly designed message dedicated to discovering relay devices, such as the third message can be called a solicitation message or a discovery message. The fourth message can be a newly designed message dedicated to responding to the third message, such as the fourth message can be called a response message. Among them, there may be many situations in which the first terminal device sends the third message. For example, the first terminal device sends the third message after determining that the relay device needs to be replaced. For example, the first terminal device can obtain the communication status between the first terminal device and the first relay device, and then determine that the relay device needs to be replaced based on the communication status. For details, please refer to the description in Example 2.

[0117] Furthermore, the first terminal device may determine that the candidate relay devices include the third terminal device according to a signal state between the third terminal device and the first terminal device.

[0118] For example, the first terminal device may determine that the candidate relay devices include the third terminal device based on the signal status between the third terminal device and the first terminal device, and the signal status between the first relay device and the first terminal device. The signal status may include signal quality and / or signal strength, for example, the signal quality may refer to reference signal receiving quality (RSRQ), and the signal strength may refer to reference signal receiving power (RSRP) or received signal strength indication (RSSI). In the following, the signal status including signal strength will be described as an example. For example, if the signal strength between the third terminal device and the first terminal device is greater than the signal strength between the first relay device and the first terminal device, the first terminal device may determine that the candidate relay devices include the third terminal device; if the signal strength between the third terminal device and the first terminal device is less than or equal to the signal strength between the first relay device and the first terminal device, the first terminal device may determine that the candidate relay devices do not include the third terminal device.

[0119] For another example, if the first terminal device determines that the signal status between the third terminal device and the first terminal device meets the first preset condition, it can be determined that the candidate relay device includes the third terminal device; if it is determined that the signal status between the third terminal device and the first terminal device does not meet the first preset condition, it can be determined that the candidate relay device does not include the third terminal device. For example, the signal status between the third terminal device and the first terminal device meets the first preset condition, which may include: the signal strength between the third terminal device and the first terminal device is greater than the first threshold; correspondingly, the signal status between the third terminal device and the first terminal device does not meet the first preset condition, which may include: the signal strength between the third terminal device and the first terminal device is less than or equal to the first threshold; wherein the first threshold may be pre-configured for the first terminal device by the access network device or the core network device. In this case, it can be understood that the selection of the relay device is controlled by the network, and the third terminal device can only be used as a relay device when the signal strength between the third terminal device and the first terminal device is greater than the first threshold. Alternatively, the first threshold value may also be generated by the first terminal device based on the QoS requirements of the communication service between the first terminal device and the second terminal device. In this case, since there is a corresponding relationship between signal strength and transmission rate, for example, the better the signal strength, the higher the corresponding transmission rate. Therefore, in one example, the first terminal device may generate a signal strength requirement based on the transmission rate requirement in the above-mentioned QoS requirement (such as the transmission rate requirement is 10Mbps, and the generated signal strength is -50dbm), and then determine the first threshold value based on the signal strength requirement (such as the first threshold value is -50dbm). Alternatively, the first threshold value may also be pre-defined by the protocol and is not specifically limited.

[0120] Implementation 2

[0121] The third terminal device sends a fifth message, which is used to indicate that the third terminal device supports relay communication. The fifth message can be sent via broadcast, for example, an announcement message. For example, after the third terminal device determines that it supports relay communication, it can periodically send the fifth message. Other terminal devices around the third terminal device (such as the first terminal device) can receive the fifth message and determine the signal status between the third terminal device and the first terminal device based on the fifth message.

[0122] Optionally, the fifth message can also be used to indicate that a communication link exists between the third terminal device and at least one terminal device. There may be multiple ways for the fifth message to indicate that a communication link exists between the third terminal device and at least one terminal device. For example, the fifth message may include an identifier of at least one terminal device. In this case, after the first terminal device receives the fifth message, it may also determine that a communication link exists between the third terminal device and at least one terminal device based on the identifier of at least one terminal device in the fifth message. Here, the at least one terminal device may include terminal device a, and the communication link between the third terminal device and terminal device a may refer to: a PC5 communication link or a PC5 connection exists between the third terminal device and terminal device a, or a path for communication between the third terminal device and terminal device a through a relay device, or a path for communication between the third terminal device and terminal device a through a core network or a server; in the embodiments of the present application, the former is mainly used as an example for description.

[0123] Furthermore, the first terminal device may determine that the candidate relay devices include the third terminal device according to a signal state between the third terminal device and the first terminal device.

[0124] For example, the first terminal device may determine that the candidate relay devices include the third terminal device based on the signal status between the third terminal device and the first terminal device, and the signal status between the first relay device and the first terminal device.

[0125] For another example, the first terminal device may determine that the candidate relay devices include the third terminal device based on the signal state between the third terminal device and the first terminal device and the first threshold.

[0126] For another example, if the fifth message includes the identifier of at least one terminal device, the first terminal device may determine that the candidate relay device includes the third terminal device based on the signal state between the third terminal device and the first terminal device, and the communication link state between the third terminal device and the second terminal device. The communication link state may include the presence or absence of a communication link. If the first terminal device determines that the fifth message includes the identifier of the second terminal device, it may be determined that a communication link exists between the third terminal device and the second terminal device; if the first terminal device determines that the fifth message does not include the identifier of the second terminal device, it may be determined that no communication link exists between the third terminal device and the second terminal device. For example, if the signal strength between the third terminal device and the first terminal device is greater than or equal to the signal strength between the first relay device and the first terminal device, and a communication link exists between the third terminal device and the second terminal device, the first terminal device may determine that the candidate relay device includes the third terminal device; otherwise (the signal strength between the third terminal device and the first terminal device is less than the signal strength between the first relay device and the first terminal device, and / or there is no communication link between the third terminal device and the second terminal device), the first terminal device may determine that the candidate relay device does not include the third terminal device. To give another example, if the signal strength between the third terminal device and the first terminal device is greater than or equal to the first threshold, and there is a communication link between the third terminal device and the second terminal device, the first terminal device can determine that the candidate relay device includes the third terminal device; otherwise (the signal strength between the third terminal device and the first terminal device is less than the first threshold, and / or there is no communication link between the third terminal device and the second terminal device), the first terminal device can determine that the candidate relay device does not include the third terminal device. In this way, through this method, the third terminal device that has a communication link (i.e., PC5 connection) with the second terminal device is determined as a candidate relay device, so that when the third terminal device is subsequently selected as the relay device between the first terminal device and the second terminal device, the third terminal device no longer needs to establish a PC5 connection with the second terminal device, which is convenient for improving efficiency and saving signaling overhead.

[0127] Implementation 3

[0128] In addition to the communication link between the first terminal device and the first relay device, the first terminal device may also have a communication link with other terminal devices (such as a third terminal device). In this case, the first terminal device can receive communication data from the third terminal device and then determine the signal status between the third terminal device and the first terminal device based on the communication data. The third terminal device can establish a direct communication path with the first terminal device, and then the third terminal device can send communication data to the first terminal device; or the third terminal device can also be a relay device between the first terminal device and other terminal devices (such as a fourth terminal device), and then after receiving the communication data from the fourth terminal device, the third terminal device can forward the communication data to the first terminal device.

[0129] Furthermore, the first terminal device may determine that the candidate relay devices include the third terminal device according to a signal state between the third terminal device and the first terminal device.

[0130] For example, the first terminal device may determine that the candidate relay devices include the third terminal device based on the signal status between the third terminal device and the first terminal device, and the signal status between the first relay device and the first terminal device.

[0131] For another example, the first terminal device may determine that the candidate relay devices include the third terminal device based on the signal state between the third terminal device and the first terminal device and the first threshold.

[0132] It should be noted that: (1) A PC5 communication link may or may not exist between the third terminal device and the first terminal device in the above-mentioned Implementation 1 or Implementation 2; a PC5 communication link may exist between the third terminal device and the first terminal device in the above-mentioned Implementation 3. In addition to the above-mentioned Implementation 1, Implementation 2, and Implementation 3, the first terminal device may also determine the signal status between the third terminal device and the first terminal device through other methods, which are not specifically limited. (2) The above-mentioned candidate relay device may be determined by the first terminal device through at least one of Implementation 1, Implementation 2, and Implementation 3.

[0133] S402, the first terminal device sends a first message to the second terminal device, where the first message is used to request to replace the relay device; accordingly, the second terminal device can receive the first message.

[0134] Here, the first message can be a newly designed message, for example, the first message can be called a relay replacement request message or a relay reselection request message, and then the second terminal device can determine that the first message is used to request the replacement of the relay device. In this case, it can be understood that the first message explicitly requests the replacement of the relay device; further, the first message can include the identifier of the candidate relay device. Alternatively, the first message is an existing message, such as a discovery message. The first message can include the identifier of the candidate relay device, and then after the second terminal device receives the first message, it can determine that the first message is used to request the replacement of the relay device based on the identifier of the candidate relay device. In this case, it can be understood that the first message implicitly requests the replacement of the relay device. Alternatively, the first message is an existing message, such as a discovery message. The first message can include the identifier of the candidate relay device and the identifier of the candidate relay device. The relay reselection indicator is used to indicate the replacement of the relay device. Then, after the second terminal device receives the first message, it can determine that the first message is used to request the replacement of the relay device based on the relay reselection indicator. In this case, it can be understood that the first message explicitly requests the replacement of the relay device. Optionally, the first message may further include a signal status between the candidate relay device and the first terminal device, and / or an address of the candidate relay device.

[0135] For example, a first terminal device may send a first message to a second terminal device via a first relay device. The first message may be a unicast message. Specifically, the first terminal device sends the first message to the first relay device via a PC5 connection between the first terminal device and the first relay device, and the first relay terminal device then forwards the first message to the second terminal device via a PC5 connection between the first terminal device and the second terminal device. Alternatively, if a direct communication path exists between the first terminal device and the second terminal device, the first terminal device may also send the first message directly to the second terminal device.

[0136] S403, the second terminal device sends indication information to the first terminal device according to the first message, where the indication information is used to instruct to replace the relay device between the second terminal device and the first terminal device with a second relay device, and the candidate relay devices include the second relay device.

[0137] Here, the indication information is used to indicate that the relay device between the second terminal device and the first terminal device is replaced with the second relay device, which can also be described as: the indication information is used to indicate that the relay device between the second terminal device and the first terminal device is updated to the second relay device, or the indication information is used to indicate that the second terminal device and the first terminal device perform relay communication through the second relay device, or the indication information is used to indicate that the relay device between the second terminal device and the first terminal device is reselected as the second relay device.

[0138] Exemplarily, the second terminal device can directly send indication information to the first terminal device, corresponding to the existence of a direct communication connection between the second terminal device and the first terminal device, for example, the indication information can be carried by PC5-S (PC5-Signalling) signaling such as a link modification request message; or, the second terminal device can also send indication information to the second terminal device through the first relay device, such as the second terminal device sends indication information to the first relay device through the PC5 connection between the second terminal device and the first relay device, and the first relay terminal device forwards the indication information to the first terminal device through the PC5 connection between the second terminal device and the first terminal device, and the indication information can be carried in a relay change response message or a response message; or, the second terminal device can also send indication information to the second terminal device through the second relay device, such as the second terminal device sends a direct communication request message to the second relay device, and the second relay terminal device sends a direct communication request message to the first terminal device, and the direct communication request message includes the indication information. If the second terminal device sends indication information directly to the first terminal device, or sends indication information to the first terminal device through the first relay device, the indication information may include the identifier of the second relay device; if the second terminal device sends indication information to the first terminal device through the second relay device, the indication information may no longer include the identifier of the second relay device. The first terminal device receives the indication information from the second relay device and can learn that the indication information is used to instruct to replace the relay device between the second terminal device and the first terminal device with the second relay device.

[0139] As mentioned above, the candidate relay devices include at least one relay device, which will be described below respectively.

[0140] (1) If the candidate relay devices include a relay device (such as a second relay device), the second terminal device may send indication information to the first terminal device based on the signal status between the second relay device and the second terminal device, and the signal status between the first relay device and the second terminal device. For example, if the signal strength between the second relay device and the second terminal device is greater than the signal strength between the first relay device and the second terminal device, indication information may be sent to the first terminal device; if the signal strength between the second relay device and the second terminal device is less than or equal to the signal strength between the first relay device and the second terminal device, no processing may be performed, such as not sending indication information to the first terminal device, or sending a response message of the first message to the first terminal device, the response message being used to indicate that the relay device between the second terminal device and the first terminal device is not to be replaced.

[0141] (2) If the candidate relay devices include at least two relay devices, the second terminal device can select or determine a relay device (such as the second relay device) from the at least two relay devices. There are multiple ways for the second terminal device to determine the second relay device. For example, the second terminal device can determine the second relay device based on the signal status between the at least two relay devices and the second terminal device. In this case, the signal strength between the second relay device and the second terminal device is greater than or equal to the signal strength between the other relay devices in the at least two relay devices and the second terminal device. After the second relay device is determined in this way, the second terminal device can send indication information to the first terminal device based on the signal status between the second relay device and the second terminal device, and the signal status between the first relay device and the second terminal device. For another example, if the first message can also include the signal status between the candidate relay device and the first terminal device, the second terminal device can determine the second relay device based on the signal status between at least two relay devices and the second terminal device, and the signal status between the candidate relay device and the first terminal device; in this case, the signal strength between the second relay device and the first terminal device is greater than the signal strength between the first relay device and the first terminal device, and the signal strength between the second relay device and the second device is greater than the signal strength between the first relay device and the second device; or, the sum of the signal strength between the second relay device and the first terminal device and the signal strength between the second relay device and the second device is greater than the sum of the signal strength between the first relay device and the first terminal device and the signal strength between the first relay device and the second device; or, the signal strength between the second relay device and the first terminal device is greater than the signal strength between the first relay device and the first terminal device, and the QoS corresponding to the signal strength between the second relay device and the second terminal device meets the QoS requirements of the communication service between the second terminal device and the first terminal device. After the second relay device is determined in this way, the second terminal device can send indication information to the first terminal device.

[0142] In the above (1) or (2), there may be multiple ways for the second terminal device to obtain the signal status between the candidate relay device and the second terminal device. For example, after receiving the first message, the second terminal device may broadcast a request message, which includes the identifier of the candidate relay device, and receive a response message from the first candidate relay device, where the first candidate relay device is any one of the candidate relay devices; and then determine the signal status between the first candidate relay device and the second terminal device based on the response message. In this case, the candidate relay device may be determined by the first terminal device through the above implementation method 1 and / or implementation method 3. It should be noted that, for the request message here, when a terminal device receives the request message, if it determines that the request message includes its own identifier, it may feedback a response message, otherwise it may not process it (i.e., it does not feedback a response message).

[0143] For another example, if the first message includes the address of a candidate relay device, then after receiving the first message, the second terminal device may send a request message to the second candidate relay device based on the address of the second candidate relay device. The request message may be sent in unicast mode, with the source address of the request message being the address of the second terminal device, and the destination address of the request message being the address of the second candidate relay device. The second candidate relay device is any one of the candidate relay devices; and, the second terminal device receives a response message from the second candidate relay device and determines the signal status between the second candidate relay device and the second terminal device based on the response message. In this case, the candidate relay device may be determined by the first terminal device through the above-mentioned implementation method 1 and / or implementation method 3.

[0144] For another example, a second terminal device receives a fifth message from a third candidate relay device, the fifth message indicating that the third candidate relay device supports relay communication. The third candidate relay device is any one of the candidate relay devices. Based on the fifth message, the second terminal device determines the signal status between the third candidate relay device and the second terminal device. In this case, the candidate relay device may be the one determined by the first terminal device using Implementation 2 above.

[0145] By adopting the above method, the first terminal device can determine the candidate relay device, and the second terminal device can determine the second relay device from the candidate relay devices, thereby replacing the relay device between the first terminal device and the second terminal device from the first relay device to the second relay device. Moreover, in this method, since the first terminal device can send the identifier of the candidate relay device to the second terminal device, the second terminal device can directly know which devices are candidate relay devices; thus, from the perspective of the relay device, it can effectively avoid the relay device forwarding broadcast messages (such as Figure 2Relay device 1 and relay device 2 need to forward broadcast messages), which can effectively save resources; from the perspective of the second terminal device, there is no need to receive broadcast messages from the relay device to identify which devices are candidate relay devices, which can effectively save the processing burden of the second terminal device. In addition, because the first terminal device considers multiple factors (such as the signal status between the candidate relay device and the first terminal device) when determining the candidate relay device, the determined candidate relay device is more reasonable; because the second terminal device also considers multiple factors (such as the signal status between the second relay device and the second terminal device) when determining the second relay device from the candidate relay devices, the selected second relay device has better transmission performance.

[0146] Example 2

[0147] Figure 5 This is a flow chart corresponding to the communication method provided in Example 2 of this application, such as Figure 5 As shown, the method includes:

[0148] S500: A first terminal device and a second terminal device perform relay communication via a first relay device.

[0149] Here, S500 may refer to S400 in the first embodiment.

[0150] S501: The first terminal device obtains the communication status between the first terminal device and the first relay device.

[0151] Here, the communication status may include a signal status and / or a QoS that can be satisfied by the communication link.

[0152] Exemplarily, there may be multiple ways for the first terminal device to obtain the signal status between the first terminal device and the first relay device. For example, the way in which the first terminal device obtains the signal status between the first terminal device and the third terminal device in the above-mentioned embodiment 1 may be referred to, and details will not be repeated here.

[0153] There may be multiple ways for the first terminal device to obtain the QoS that can be satisfied by the communication link between the first terminal device and the first relay device. For example, the first terminal device may determine the QoS that can be satisfied by the communication link between the first terminal device and the first relay device based on the transmission rate between the first terminal device and the first relay device. For another example, the first terminal device may use the QoS corresponding to the signal status between the first terminal device and the third terminal device as the QoS that can be satisfied by the communication link between the first terminal device and the first relay device. For example, if the QoS that can be satisfied by the communication link between the first terminal device and the first relay device includes the transmission rate supported by the communication link between the first terminal device and the first relay device, the transmission rate supported by the communication link may be determined based on the signal strength between the first terminal device and the first relay device.

[0154] S502: The first terminal device sends a sixth message according to the communication status, where the sixth message is used to request a replacement of the relay device (or the sixth message is used to replace the relay device). The sixth message may be sent in a broadcast manner.

[0155] Here, the first terminal device determines, based on the communication status, that the relay device between the first terminal device and the second terminal device needs to be replaced, and then the sixth message may be sent.

[0156] For example, the first terminal device determines that the relay device between the first terminal device and the second terminal device needs to be replaced based on the QoS that can be met by the communication link between the first terminal device and the first relay device, and the QoS requirements of the communication service between the first terminal device and the second terminal device. For example, if the first terminal device determines that the transmission rate supported by the communication link between the first terminal device and the first relay device cannot meet the transmission rate requirements of the communication service between the first terminal device and the second terminal device, then it determines that the relay device between the first terminal device and the second terminal device needs to be replaced.

[0157] For another example, if the first terminal device determines that the signal status between the first terminal device and the first relay device does not satisfy the second preset condition, then it is determined that the relay device between the first terminal device and the second terminal device needs to be replaced; if it is determined that the signal status between the first terminal device and the first relay device satisfies the second preset condition, then there is no need to replace the relay device between the first terminal device and the second terminal device. The fact that the signal status between the first terminal device and the first relay device does not satisfy the second preset condition may include: the signal strength between the first terminal device and the first relay device is less than or equal to the second threshold; correspondingly, the fact that the signal status between the first terminal device and the first relay device satisfies the second preset condition may include: the signal strength between the first terminal device and the first relay device is greater than the second threshold. Among them, the second threshold can be pre-configured for the first terminal device by the access network device or the core network device. In this case, it can be understood that the network controls whether to replace the relay device. The first relay device can only be replaced when the signal strength between the first terminal device and the first relay device is less than or equal to the second threshold; or, the second threshold can also be generated by the first terminal device according to the QoS requirements of the communication service between the first terminal device and the second terminal device; or, the second threshold can also be pre-defined by the protocol, and there is no specific limitation.

[0158] For another example, the first terminal device determines whether it is necessary to replace the relay device between the first terminal device and the second terminal device based on the signal status between the first terminal device and the first relay device, the second preset condition, the QoS that can be met by the communication link between the first terminal device and the first relay device, and the QoS requirements of the communication service between the first terminal device and the second terminal device. For example, if the first terminal device determines that the QoS that can be met by the communication link between the first terminal device and the first relay device cannot meet the QoS requirements of the communication service between the first terminal device and the second terminal device, and the signal status between the first terminal device and the first relay device does not meet the second preset condition, it can be determined that the relay device between the first terminal device and the second terminal device needs to be replaced. Otherwise, it can be determined that it is not necessary to replace the relay device between the first terminal device and the second terminal device.

[0159] S503, other terminal devices around the first terminal device (such as candidate relay devices) receive the sixth message and send a seventh message according to the sixth message; correspondingly, the second terminal device receives the seventh message from the candidate relay device.

[0160] Here, the candidate relay devices may include at least one relay device other than the first relay device. For example, since the first relay device may also receive the sixth message, the candidate relay devices may also include the first relay device. In other words, the candidate relay devices may include at least two relay devices.

[0161] For example, the sixth message may be the request message described above (eg Figure 2 The sixth message may include the identifier of the second terminal device and relay indication information (relay_indication=1). Furthermore, the sixth message may also include at least one of a relay reselection indication, a signal status requirement, and a QoS requirement.

[0162] For example, in one example, the sixth message may also include a relay reselection indication, and then after the first candidate relay device (the first candidate relay device may be any one of the candidate relay devices) receives the sixth message, it can determine, based on the relay reselection indication, that the sixth message is used to request a replacement of the relay device, and then the signal status between the first candidate relay device and the first terminal device can be carried in the seventh message, and the seventh message can be sent. That is, the seventh message may include the identifier of the second terminal device, the relay indication information (relay_indication=0), and the signal status between the first candidate relay device and the first terminal device.

[0163] In another example, the sixth message may also include a signal status requirement, wherein the first terminal device may determine the signal status requirement based on the signal status between the first terminal device and the first relay device, for example, the signal status requirement is the signal strength between the first terminal device and the first relay device. In this case, after receiving the sixth message, the first candidate relay device may determine whether the signal status between the first candidate relay device and the first terminal device meets the signal status requirement. If so, the signal status between the first candidate relay device and the first terminal device is greater than the signal strength between the first terminal device and the first relay device. The signal status between the first candidate relay device and the first terminal device is carried in the seventh message and the seventh message is sent. That is, the seventh message may include the identifier of the second terminal device, relay indication information (relay_indication=0), and the signal status between the first candidate relay device and the first terminal device. If not, the signal strength between the first candidate relay device and the first terminal device is less than or equal to the signal strength between the first terminal device and the first relay device. The seventh message may no longer be sent.

[0164] Alternatively, the sixth message may also include a QoS requirement, wherein the first terminal device may determine the QoS requirement based on the QoS that can be met by the communication link between the first terminal device and the first relay device, such as the QoS requirement being the QoS that can be met by the communication link between the first terminal device and the first relay device. In this case, after receiving the sixth message, the first candidate relay device may determine whether the QoS corresponding to the signal state between the first candidate relay device and the first terminal device meets the QoS requirement (such as whether the transmission rate corresponding to the signal state between the first candidate relay device and the first terminal device meets the transmission rate requirement in the QoS requirement). If so, the signal state between the first candidate relay device and the first terminal device is greater than the QoS that can be met by the communication link between the first terminal device and the first relay device. The signal state between the first candidate relay device and the first terminal device is carried in the seventh message and the seventh message is sent. If not, the signal state between the first candidate relay device and the first terminal device is less than or equal to the QoS that can be met by the communication link between the first terminal device and the first relay device. The seventh message may no longer be sent.

[0165] Alternatively, the sixth message may also include signal status requirements and QoS requirements. In this case, after the first candidate relay device receives the sixth message, it can determine whether the signal status between the first candidate relay device and the first terminal device meets the signal status requirements, and whether the QoS corresponding to the signal status between the first candidate relay device and the first terminal device meets the QoS requirements (for example, whether the transmission rate corresponding to the signal status between the first candidate relay device and the first terminal device meets the transmission rate requirement in the QoS requirement). If the signal status between the first candidate relay device and the first terminal device meets the signal status requirements, and the QoS corresponding to the signal status between the first candidate relay device and the first terminal device meets the QoS requirements, the signal status between the first candidate relay device and the first terminal device is carried in the seventh message, and the seventh message is sent; otherwise, the seventh message may no longer be sent.

[0166] In the above example, since the sixth message includes signal status requirements and / or QoS requirements, the terminal device that receives the sixth message can send the seventh message when the signal status requirements and / or QoS requirements are met, and may not send the seventh message when the signal status requirements and / or QoS requirements are not met. This can avoid some terminal devices that are not suitable as candidate relay devices from sending the seventh message, effectively reducing signaling overhead.

[0167] It should be noted that, in other possible implementations, the sixth message may also be a newly designed dedicated message requesting to replace the relay device, and the sixth message may include at least one of a relay reselection indication, a signal status requirement, and a QoS requirement.

[0168] S504: The second terminal device sends indication information to the first terminal device according to the signal status between the candidate relay device and the first terminal device and the signal status between the candidate relay device and the second terminal device.

[0169] Here, the indication information may be used to indicate that the relay device between the first terminal device and the second terminal device is replaced with the second relay device, and the candidate relay devices include the second relay device.

[0170] Exemplarily, after the second terminal device receives the seventh message from the candidate relay device, it can determine the signal status between the candidate relay device and the second terminal device based on the seventh message; and then determine the second relay device based on the signal status between the candidate relay device and the first terminal device and the signal status between the candidate relay device and the second terminal device. In this case, the signal strength between the second relay device and the first terminal device is greater than the signal strength between the first relay device and the first terminal device, and the signal strength between the second relay device and the second device is greater than the signal strength between the first relay device and the second device; or, the sum of the signal strength between the second relay device and the first terminal device and the signal strength between the second relay device and the second device is greater than the sum of the signal strength between the first relay device and the first terminal device and the signal strength between the first relay device and the second device; or, the signal strength between the second relay device and the first terminal device is greater than the signal strength between the first relay device and the first terminal device, and the transmission rate corresponding to the signal strength between the second relay device and the second terminal device meets the transmission rate requirement in the QoS requirement of the communication service between the second terminal device and the first terminal device. After the second relay device is determined in this manner, the second terminal device may send indication information to the first terminal device.

[0171] There are various ways in which the second terminal device can send the instruction information to the first terminal device. For example, the second terminal device can directly send the instruction information to the first terminal device; alternatively, the second terminal device can send the instruction information to the second terminal device via the first relay device; or alternatively, the second terminal device can send the instruction information to the second terminal device via the second relay device. For details, please refer to S403 in Example 1 and will not be repeated here.

[0172] Using the above method, after the first terminal device determines that the relay device needs to be replaced, it can broadcast the sixth message, thereby triggering the candidate relay device to send the seventh message to the second terminal device, so that the second terminal device can determine the second relay device from the candidate relay devices, thereby replacing the relay device between the first terminal device and the second terminal device from the first relay device to the second relay device; and because the second terminal device considers multiple factors (such as the signal status between the second relay device and the second terminal device) when determining the second relay device from the candidate relay devices, the relay transmission performance of the selected second relay device is better than that of the first relay device.

[0173] Example 3

[0174] In the above-mentioned embodiments 1 and 2, a scenario in which a single relay device is provided between the first terminal device and the second terminal device is used as an example to describe how to replace the relay device between the first terminal device and the second terminal device. It is understood that the methods in the embodiments of the present application can also be applied to scenarios in which multiple relay devices are provided between the first terminal device and the second terminal device. The following describes a possible implementation by applying the method described in the above-mentioned embodiment 2 to a scenario in which two relay devices are provided between the first terminal device and the second terminal device.

[0175] Figure 6 See the flow chart corresponding to the communication method provided in Example 3 of this application. Figure 6 As shown, the method may include:

[0176] S600: A first terminal device and a second terminal device perform relay communication via relay device 1 and relay device 2.

[0177] For example, PC5 connection 1 is established between the first terminal device and relay device 1, PC5 connection 2 is established between relay device 1 and relay device 2, and PC5 connection 3 is established between relay device 2 and the second terminal device. Taking the example of data transmission from the first terminal device to the second terminal device, the first terminal device can send the data to relay device 1 via PC5 connection 1. After receiving the data, relay device 1 sends the data to relay device 2 via PC5 connection 2. After receiving the data, relay device 2 sends the data to the second terminal device via PC5 connection 3.

[0178] S601: A first terminal device determines that a relay device between the first terminal device and a second terminal device needs to be replaced.

[0179] Here, there may be multiple situations in which the first terminal device determines that the relay device between the first terminal device and the second terminal device needs to be replaced. For example, referring to Example 2, after the first terminal device obtains the communication status between the first terminal device and the relay device 1, it determines that the relay device between the first terminal device and the second terminal device needs to be replaced based on the communication status.

[0180] S602: The first terminal device sends a message 1, wherein the message 1 is used to request a replacement of the relay device. The message 1 may be sent in a broadcast manner.

[0181] Exemplarily, message 1 may be the discovery request message described above, and may include the identifier of the second terminal device and relay indication information (relay_indication=2). Further, message 1 may also include at least one of a relay reselection indication, a signal status requirement, and a QoS requirement.

[0182] S603: After receiving message 1, candidate relay device 1 may send message 2. Message 2 may be sent in a broadcast manner.

[0183] Here, message 2 may include the identifier of the second terminal device, relay indication information (relay_indication=1), and the signal status between the candidate relay device 1 and the first terminal device, and may also include at least one of the relay reselection indication, signal status requirement, and QoS requirement.

[0184] The implementation related to the candidate relay device 1 sending the message 2 according to the message 1 can refer to the implementation related to the first candidate relay device sending the seventh message according to the sixth message, which will not be repeated here.

[0185] S604: After receiving the message 2 from the candidate relay device 1, the candidate relay device 2 may send a message 3 according to the message 2. The message 3 may be sent in a broadcast manner.

[0186] Here, message 3 includes the identifier of the second terminal device, relay indication information (relay_indication=0), the signal status between candidate relay device 1 and the first terminal device, and the signal status between candidate relay device 2 and candidate relay device 1.

[0187] The implementation related to the candidate relay device 2 sending the message 3 according to the message 2 can refer to the implementation related to the first candidate relay device sending the seventh message according to the sixth message, which will not be repeated here.

[0188] S605: After receiving message 3 from candidate relay device 2, the second terminal device may send instruction information to the first terminal device based on the signal status between the second terminal device and candidate relay device 2, the signal status between candidate relay device 2 and candidate relay device 1, and the signal status between candidate relay device 1 and the first terminal device. For example, the instruction information may be used to instruct the first terminal device to replace the relay devices between the second terminal device and the first terminal device with candidate relay device 1 and candidate relay device 2.

[0189] It should be noted that the above process is described using candidate relay device 1 and candidate relay device 2 as examples. In specific implementation, in addition to receiving message 3 sent by candidate relay device 2, the second terminal device may also receive message 3 sent by multiple other candidate relay devices. The second terminal device can select a path from multiple paths. For example, the second terminal device selects a path passing through candidate relay device 1 and candidate relay device 2, and then can send indication information to the first terminal device.

[0190] Among them, there are many ways for the second terminal device to select a path from multiple paths. For example, the second terminal device can comprehensively consider the signal status between the two adjacent devices on each path (such as the signal status between the second terminal device and the candidate relay device 2, the signal status between the candidate relay device 2 and the candidate relay device 1, and the signal status between the candidate relay device 1 and the first terminal device) to select a path. For example, path 1 is selected, and the sum of the signal strengths between the two adjacent devices on path 1 is greater than the sum of the signal strengths between the two adjacent devices on other paths in the multiple paths, or the signal strengths between the two adjacent devices on path 1 are both greater than a preset threshold. The details will not be repeated here.

[0191] By adopting the above method, when a plurality of relay devices are included between the first terminal device and the second terminal device, the relay devices can also be flexibly replaced.

[0192] Regarding the above-mentioned Embodiments 1, 2 and 3, it should be noted that:

[0193] (1) The above-mentioned Embodiments 1, 2, and 3 focus on the differences between the different embodiments. Except for the differences, Embodiments 1, 2, and 3 can refer to each other. In addition, different implementations of the same embodiment can also refer to each other.

[0194] (2) The step numbers in the flowcharts described in the above embodiments are merely examples of the execution process and do not limit the order in which the steps are executed. In the embodiments of the present application, there is no strict execution order between steps that have no temporal dependencies. In addition, not all steps shown in the flowcharts are mandatory steps, and some steps may be added or deleted based on actual needs.

[0195] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of device interaction. It is understandable that, in order to implement the above functions, each device may include a hardware structure and / or software module that performs each function. Those skilled in the art should easily appreciate that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the embodiments of the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in a hardware or computer software driven hardware manner depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0196] In the embodiments of the present application, the functional units of the device can be divided according to the above method examples. For example, each functional unit can be divided according to each function, or two or more functions can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or software functional units.

[0197] In the case of an integrated unit, Figure 7 FIG. 1 shows a possible exemplary block diagram of the device involved in the embodiments of the present application. Figure 7 As shown, apparatus 700 may include a processing unit 702 and a communication unit 703. Processing unit 702 is used to control and manage the operations of apparatus 700. Communication unit 703 is used to support communication between apparatus 700 and other devices. Optionally, communication unit 703 is also referred to as a transceiver unit and may include a receiving unit and / or a sending unit, each configured to perform receiving and sending operations. Optionally, apparatus 700 may also include a storage unit 701 for storing program code and / or data of apparatus 700.

[0198] The apparatus 700 may be the first terminal device in the above-described embodiment, or may be a chip disposed in the first terminal device. The processing unit 702 may support the apparatus 700 in executing the actions of the first terminal device in each of the above-described method examples. Alternatively, the processing unit 702 may primarily execute internal actions of the first terminal device in the method examples, and the communication unit 703 may support communication between the apparatus 700 and other devices.

[0199] Specifically, in one embodiment, the processing unit 703 is used to: determine a candidate relay device, wherein the candidate relay device includes at least one relay device; the communication unit 703 is used to: send a first message to the second terminal device, wherein the first message is used to request to replace the relay device, and the first message includes an identifier of the candidate relay device.

[0200] In one possible design, the communication unit 703 is specifically used to: send the first message to the second terminal device through the first relay device.

[0201] In one possible design, the first message also includes: the signal status between the candidate relay device and the first terminal device, and / or the address of the candidate relay device.

[0202] In one possible design, the processing unit 703 is specifically used to: determine that the candidate relay device includes the third terminal device based on the signal status between the third terminal device and the first terminal device; wherein the signal status includes signal quality and / or signal strength.

[0203] In one possible design, the processing unit 703 is specifically used to: determine that the candidate relay devices include the third terminal device based on the signal status between the third terminal device and the first terminal device, and the signal status between the first relay device and the first terminal device; or, determine that the candidate relay devices include the third terminal device based on the signal status between the third terminal device and the first terminal device, the signal status between the first relay device and the first terminal device, and the communication link status between the third terminal device and the second terminal device; wherein the communication link status includes the existence of a communication link or the non-existence of a communication link.

[0204] In one possible design, the processing unit 702 is further used to obtain a signal status between the third terminal device and the first terminal device.

[0205] In one possible design, the communication unit 703 is also used to: send a third message, wherein the third message is used to discover a relay device; receive a fourth message from the third terminal device, wherein the fourth message is used to respond to the third message; and the processing unit 702 is also used to: determine the signal status between the third terminal device and the first terminal device based on the fourth message.

[0206] In one possible design, the communication unit 703 is also used to: receive a fifth message from the third terminal device, where the fifth message is used to indicate that the third terminal device supports relay communication; the communication unit 703 is also used to: determine the signal status between the third terminal device and the first terminal device based on the fifth message.

[0207] In one possible design, the processing unit 702 is further used to obtain a communication link status between the third terminal device and the second terminal device.

[0208] In one possible design, the communication unit 703 is also used to: receive a fifth message from the third terminal device, the fifth message including an identifier of the second terminal device, the fifth message being used to indicate that the third terminal device supports relay communication and that a communication link exists between the third terminal device and the second terminal device; the processing unit 702 is also used to: determine the communication link status between the third terminal device and the second terminal device based on the fifth message.

[0209] The apparatus 700 may be the third terminal device described in the above embodiments, or may be a chip disposed within the third terminal device. The processing unit 702 may support the apparatus 700 in executing the actions of the third terminal device described in the above method examples. Alternatively, the processing unit 702 may primarily execute the internal actions of the third terminal device described in the method examples, and the communication unit 703 may support communication between the apparatus 700 and other devices.

[0210] Specifically, in one embodiment, the processing unit 702 is used to: obtain the identification of at least one terminal device that has a communication link with the third terminal device; the communication unit 703 is used to: send a fifth message, wherein the fifth message includes the identification of the at least one terminal device, and the fifth message is used to indicate that the third terminal device supports relay communication and that a communication link exists between the third terminal device and the at least one terminal device.

[0211] The apparatus 700 may be the second terminal device in the above-described embodiments, or may be a chip disposed within the second terminal device. The processing unit 702 may support the apparatus 700 in executing the actions of the second terminal device in the above-described method examples. Alternatively, the processing unit 702 may primarily execute internal actions of the second terminal device in the method examples, and the communication unit 703 may support communication between the apparatus 700 and other devices.

[0212] Specifically, in one embodiment, the communication unit 703 is used to: receive a first message from the first terminal device, the first message is used to request to replace the relay device, the first message includes an identification of a candidate relay device, and the candidate relay device includes at least one relay device; and, based on the first message, send indication information to the first terminal device, the indication information is used to indicate that the relay device between the second terminal device and the first terminal device is replaced with the second relay device, and the candidate relay device includes the second relay device.

[0213] In one possible design, the candidate relay devices include at least two relay devices, and the processing unit 702 is further used to determine the second relay device based on the signal status between the at least two relay devices and the second terminal device.

[0214] In one possible design, the communication unit 703 is specifically used to: send the indication information to the first terminal device based on the signal status between the second relay device and the second terminal device, and the signal status between the first relay device and the second terminal device.

[0215] In one possible design, the candidate relay device includes at least two relay devices, and the first message also includes the signal status between the candidate relay device and the first terminal device; the processing unit 702 is also used to: determine the second relay device based on the signal status between the candidate relay device and the first terminal device, and the signal status between the candidate relay device and the second terminal device.

[0216] In one possible design, the processing unit 702 is further used to obtain a signal status between the candidate relay device and the second terminal device.

[0217] In one possible design, the communication unit 703 is also used to: broadcast a request message, the request message including the identifier of a first candidate relay device, the first candidate relay device being any one of the candidate relay devices; receive a response message from the first candidate relay device; the processing unit 702 is also used to: determine the signal status between the first candidate relay device and the second terminal device based on the response message.

[0218] In one possible design, the first message also includes the address of the candidate relay device; the communication unit 703 is also used to: send a request message to the second candidate relay device according to the address of the second candidate relay device, where the second candidate relay device is any one of the candidate relay devices; receive a response message from the second candidate relay device; the processing unit 702 is also used to: determine the signal status between the second candidate relay device and the second terminal device according to the response message.

[0219] In one possible design, the communication unit 703 is also used to: receive a fifth message from a third candidate relay device, the fifth message being used to indicate that the third candidate relay device supports relay communication, and the third candidate relay device is any one of the candidate relay devices; the processing unit 702 is also used to: determine the signal status between the third candidate relay device and the second terminal device based on the fifth message.

[0220] It should be understood that the division of units in the above device is merely a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. Moreover, the units in the device can all be implemented in the form of software calling through processing elements; or they can all be implemented in the form of hardware; or some units can be implemented in the form of software calling through processing elements, and some units can be implemented in the form of hardware. For example, each unit can be a separately established processing element, or it can be integrated into a certain chip of the device. In addition, it can also be stored in the memory in the form of a program, called by a certain processing element of the device and execute the function of the unit. In addition, all or part of these units can be integrated together, or they can be implemented independently. The processing element described here can also be a processor, which can be an integrated circuit with signal processing capabilities. In the implementation process, each operation of the above method or each unit above can be implemented by the integrated logic circuit of the hardware in the processor element or in the form of software calling through the processing element.

[0221] In one example, the unit in any of the above devices may be one or more integrated circuits configured to implement the above method, such as one or more application specific integrated circuits (ASICs), or one or more digital singnal processors (DSPs), or one or more field programmable gate arrays (FPGAs), or a combination of at least two of these integrated circuit forms. For another example, when the unit in the device can be implemented in the form of a processing element scheduler, the processing element can be a processor, such as a general-purpose central processing unit (CPU), or other processor that can call a program. For another example, these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0222] The above-mentioned receiving unit is an interface circuit of the device, which is used to receive signals from other devices. For example, when the device is implemented as a chip, the receiving unit is the interface circuit of the chip used to receive signals from other chips or devices. The above-mentioned sending unit is an interface circuit of the device, which is used to send signals to other devices. For example, when the device is implemented as a chip, the sending unit is the interface circuit of the chip used to send signals to other chips or devices.

[0223] Figure 8 This is a schematic diagram of the structure of a terminal device provided in an embodiment of the present application, which may be the first terminal device, the second terminal device, the relay device, etc. in the above embodiments, and is used to implement the operations of each device in the above embodiments. Figure 8 As shown, the terminal device includes an antenna 810, a radio frequency section 820, and a signal processing section 830. Antenna 810 is connected to radio frequency section 820. In the downlink direction, radio frequency section 820 receives information sent by network devices via antenna 810 and sends the information to signal processing section 830 for processing. In the uplink direction, signal processing section 830 processes the information from the terminal device and sends it to radio frequency section 820. Radio frequency section 820 then processes the information from the terminal device and sends it to the network device via antenna 810.

[0224] The signal processing unit 830 may include a modem subsystem for processing data at various communication protocol layers; a central processing unit for processing the terminal device's operating system and application layers; and other subsystems, such as a multimedia subsystem for controlling the terminal device's camera and screen display, and a peripheral subsystem for connecting to other devices. The modem subsystem may be a separate chip.

[0225] The modem subsystem may include one or more processing elements 831, such as a main control CPU and other integrated circuits. Furthermore, the modem subsystem may include a storage element 832 and an interface circuit 833. Storage element 832 is used to store data and programs. However, the program used to execute the method performed by the terminal device in the above method may not be stored in storage element 832, but rather in a memory external to the modem subsystem, and loaded by the modem subsystem when in use. Interface circuit 833 is used to communicate with other subsystems.

[0226] The modem subsystem can be implemented using a chip comprising at least one processing element and an interface circuit, wherein the processing element is configured to execute each step of any of the methods performed by the terminal device described above, and the interface circuit is configured to communicate with other devices. In one implementation, the unit for implementing each step of the method described above can be implemented as a processing element scheduler. For example, the terminal device may include a processing element and a storage element, with the processing element invoking a program stored in the storage element to execute the method performed by the terminal device in the above method embodiments. The storage element can be a storage element located on the same chip as the processing element, i.e., an on-chip storage element.

[0227] In another implementation, the program for executing the method executed by the terminal device in the above method can be stored in a memory element on a different chip from the processing element, i.e., an off-chip memory element. In this case, the processing element calls or loads the program from the off-chip memory element to the on-chip memory element to call and execute the method executed by the terminal device in the above method embodiment.

[0228] In another implementation, the unit of the terminal device that implements each step of the above method may be configured as one or more processing elements, which are provided in the modem subsystem. The processing elements here may be integrated circuits, such as one or more ASICs, one or more DSPs, one or more FPGAs, or a combination of these integrated circuits. These integrated circuits may be integrated together to form a chip.

[0229] The units that implement the various steps of the above method in the terminal device can be integrated together and implemented in the form of a SOC chip, which is used to implement the above method. The chip can integrate at least one processing element and a storage element, and the method performed by the terminal device can be implemented by the processing element calling the program stored in the storage element; alternatively, the chip can integrate at least one integrated circuit to implement the method performed by the terminal device; alternatively, the above implementation methods can be combined, with the functions of some units being implemented by the processing element calling the program, and the functions of some units being implemented by the integrated circuit.

[0230] As can be seen, the above-mentioned apparatus for a terminal device may include at least one processing element and an interface circuit, wherein the at least one processing element is used to execute any of the methods provided in the above method embodiments. The processing element may execute some or all of the steps executed by the terminal device in a first manner: by calling a program stored in a storage element; or in a second manner: by executing some or all of the steps executed by the terminal device through the hardware integrated logic circuit in the processor element in combination with instructions. Of course, the first and second manners may also be combined to execute some or all of the steps executed by the terminal device.

[0231] The processing element here is the same as described above and can be implemented by a processor. The function of the processing element can be Figure 7 The processing unit described in the preceding claims has the same function. For example, the processing element may be a general-purpose processor, such as a CPU, or one or more integrated circuits configured to implement the above method, such as one or more ASICs, or one or more microprocessors DSPs, or one or more FPGAs, or a combination of at least two of these integrated circuit forms. The storage element may be implemented by a memory, and the function of the storage element may be the same as Figure 7 The function of the storage unit described in the above is the same. The storage element can be realized by a memory, and the function of the storage element can be the same as Figure 7 The storage element can be a single memory or a collective term for multiple memories.

[0232] Figure 8 The terminal device shown is capable of implementing various processes related to the terminal device in the above method embodiment. Figure 8 The operations and / or functions of the various modules in the terminal device shown are for implementing the corresponding processes in the above method embodiments. For details, please refer to the description in the above method embodiments. To avoid repetition, detailed description is appropriately omitted here.

[0233] The terms "system" and "network" in the embodiments of the present application can be used interchangeably. "At least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of A, B and C" includes A, B, C, AB, AC, BC or ABC. And, unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, and are not used to limit the order, timing, priority or importance of multiple objects.

[0234] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0235] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0236] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0237] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps of the functions specified in one or more blocks. Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if such modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include such modifications and variations.

Claims

1. A communication method, characterized in that: The method is applied to a first terminal device, where the first terminal device performs relay communication with a second terminal device via a first relay device, and the method includes: Determining candidate relay devices, where the candidate relay devices include at least one relay device; Sending a first message to the second terminal device, the first message including an identifier of the candidate relay device, an address of the candidate relay device, and a relay reselection indication, wherein the relay reselection indication is used to indicate a replacement of the relay device; wherein the address of the candidate relay device is used to determine a signal status between the candidate relay device and the second terminal device; Receive indication information based on the first message from the second terminal device, the indication information is used to indicate that the relay device between the second terminal device and the first terminal device is replaced with a second relay device, the indication information includes the identifier of the second relay device, and the candidate relay device includes the second relay device.

2. The method according to claim 1, characterized in that The determining of the candidate relay device includes: According to a signal state between a third terminal device and the first terminal device, it is determined that the candidate relay devices include the third terminal device; wherein the signal state includes signal quality and / or signal strength.

3. The method according to claim 2, characterized in that The determining, based on a signal state between the third terminal device and the first terminal device, that the candidate relay device includes the third terminal device includes: determining, based on a signal state between the third terminal device and the first terminal device, and a signal state between the first relay device and the first terminal device, that the candidate relay devices include the third terminal device; or Based on the signal status between the third terminal device and the first terminal device, the signal status between the first relay device and the first terminal device, and the communication link status between the third terminal device and the second terminal device, it is determined that the candidate relay devices include the third terminal device; wherein the communication link status includes the existence of a communication link or the non-existence of a communication link.

4. The method according to claim 2 or 3, characterized in that The method further comprises: Obtain a signal status between the third terminal device and the first terminal device.

5. The method according to claim 4, characterized in that The obtaining of a signal status between the third terminal device and the first terminal device includes: receiving an announcement message from the third terminal device; According to the announcement message, a signal status between the third terminal device and the first terminal device is determined.

6. A communication method, characterized in that: The method is applied to a second terminal device, where the second terminal device performs relay communication with the first terminal device via a first relay device, and the method includes: receiving a first message from the first terminal device, the first message including an identifier of a candidate relay device, an address of the candidate relay device, and a relay reselection indication, the candidate relay device including at least one relay device, and the relay reselection indication being used to instruct a relay device to be replaced; Obtaining, according to the address of the candidate relay device, a signal status between the candidate relay device and the second terminal device; Determining a second relay device from the candidate relay devices according to a signal state between the candidate relay device and the second terminal device; Send indication information to the first terminal device, where the indication information is used to indicate that the relay device between the second terminal device and the first terminal device is replaced with the second relay device, the indication information includes an identifier of the second relay device, and the candidate relay device includes the second relay device.

7. The method according to claim 6, characterized in that The candidate relay devices include at least two relay devices, and determining the second relay device from the candidate relay devices according to a signal state between the candidate relay devices and the second terminal device includes: The second relay device is determined from the at least two relay devices according to the signal status between the at least two relay devices and the second terminal device.

8. The method according to claim 7, characterized in that The sending indication information to the first terminal device includes: The indication information is sent to the first terminal device according to the signal status between the second relay device and the second terminal device, and the signal status between the first relay device and the second terminal device.

9. The method according to claim 8, characterized in that The obtaining, according to the address of the candidate relay device, a signal status between the candidate relay device and the second terminal device, includes: Sending a request message to the second candidate relay device according to the address of the second candidate relay device, where the second candidate relay device is any one of the candidate relay devices; receiving a response message from the second candidate relay device; Determine a signal status between the second candidate relay device and the second terminal device according to the response message.

10. A communication device, characterized in that: The method comprises means for executing the method according to any one of claims 1 to 5.

11. A communication device, characterized in that: Comprising means for executing the method as claimed in any one of claims 6 to 9.

12. A communication device, characterized in that: The communication device comprises a processor coupled to a memory, wherein a computer program is stored in the memory; the processor is used to call the computer program in the memory so that the communication device executes the method according to any one of claims 1 to 5.

13. A communication device, characterized in that: The communication device comprises a processor coupled to a memory, wherein a computer program is stored in the memory; the processor is used to call the computer program in the memory so that the communication device executes the method according to any one of claims 6 to 9.

14. A computer-readable storage medium, characterized in that The storage medium stores a computer program or instruction. When the computer program or instruction is executed by the communication device, the method according to any one of claims 1 to 5 or the method according to any one of claims 6 to 9 is implemented.

15. A communication system, characterized in that: include: a first terminal device and a second terminal device; The first terminal device is used to perform the method according to any one of claims 1 to 5; The second terminal device is configured to execute the method according to any one of claims 6 to 9.

16. A computer program product, characterized in that When a computer reads and executes the computer program or instructions in the computer program product, the method according to any one of claims 1 to 5 or the method according to any one of claims 6 to 9 is implemented.

17. A chip, characterized in that: The chip includes a processor coupled to a memory, and configured to read and execute a software program stored in the memory to implement the method according to any one of claims 1 to 5, or the method according to any one of claims 6 to 9.

Images