A communication method, apparatus, and storage medium

Abstract

The embodiment of the application provides a communication method, device and storage medium, the method comprises the following steps: a first terminal device receives a first broadcast message sent by a second terminal device; if the first terminal device does not receive a second broadcast message from the second terminal device within a first time length after receiving the first broadcast message, it is determined that the second terminal device is not a relay device of the first terminal device. By using the embodiment of the application, whether a terminal device is suitable for being a relay terminal can be determined more accurately.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method, apparatus, and storage medium. Background Technology

[0002] In a UE-to-Network Relay (U2N Relay) communication system, a remote terminal can communicate with network devices via a relay terminal. The remote terminal and the relay terminal communicate via a sidelink (SL), with the corresponding interface called PC5. The relay terminal and the network device are directly connected, communicating via an air interface (such as the Uu interface).

[0003] In a U2N Relay communication system, remote terminals can measure the communication quality of the current serving cell and its sidelinks with surrounding relay terminals based on the network device configuration, facilitating mobility management. For example, a remote terminal can switch from a direct connection to the network device to a connection via a relay terminal. Based on the measurement results, the remote terminal determines a suitable relay device and reports it to the network device, enabling the network device to make a decision from the reported relay devices and allow the remote terminal to switch to the appropriate relay terminal.

[0004] Generally, a remote terminal can measure the signal quality between itself and the relay terminal based on the discovery message broadcast by the relay terminal, and determine whether the relay terminal is suitable as a relay device for the remote terminal based on the signal quality. However, the above method cannot accurately determine whether a relay terminal is suitable as a relay device for a remote terminal. Summary of the Invention

[0005] This application provides a communication method, apparatus, and storage medium that can more accurately determine whether a terminal device is suitable as a relay terminal.

[0006] In a first aspect, embodiments of this application provide a communication method, the method comprising:

[0007] The first terminal device receives a first broadcast message sent by the second terminal device; if the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message, it is determined that the second terminal device is not a relay device of the first terminal device.

[0008] In this embodiment, the first broadcast message and the second broadcast message can be discovery messages sent by the first terminal device at different times. These discovery messages instruct the second terminal device to provide relay services. Generally, the second terminal device periodically broadcasts discovery messages when providing relay services. When not providing relay services, the second terminal device stops sending discovery messages. Therefore, if the first terminal device does not receive the second broadcast message within a first time period after receiving the first broadcast message, it can determine that the second terminal device is no longer suitable as a relay device. Thus, the first terminal device can identify unsuitable terminal devices, i.e., it can more accurately determine whether the second terminal device is suitable as a relay device for the first terminal device.

[0009] In one possible implementation, after determining that the second terminal device is not a relay device of the first terminal device, the method further includes: the first terminal device deleting the measurement information corresponding to the second terminal device.

[0010] In this embodiment, after determining that the second terminal device is not a relay device for the first terminal device, i.e., the second terminal device is not suitable to be a relay device for the first terminal device, the first terminal device may not report the measurement information corresponding to the second terminal device to the network device. Therefore, the first terminal device can delete the measurement information corresponding to the second terminal device from the measurement results, avoiding the inclusion of inappropriate terminal device corresponding measurement information in the measurement results reported by the first terminal device, ensuring that the measurement results include appropriate terminal device measurement information, saving memory space occupied by the measurement results, and reducing the resources required to report the measurement results.

[0011] In one possible implementation, a unicast connection exists between the first terminal device and the second terminal device. After determining that the second terminal device is not a relay device for the first terminal device, the method further includes at least one of the following: the first terminal device determines to reselect a relay device; or, the first terminal device reports the measurement results to the first network device.

[0012] In this embodiment, the second terminal device is currently a relay device for the first terminal device. The determination that the second terminal device is no longer a relay device for the first terminal device can be understood as the second terminal device no longer being a relay device for the first terminal device. Therefore, the first terminal device can perform relay device reselection or trigger measurement reporting to switch its relay device to a suitable terminal device. For example, when the first terminal device is in RRC connected state, after determining that the second terminal device is no longer a relay device for the first terminal device, the first terminal device can trigger measurement reporting to report measurement results to the first network device, so that the first network device can instruct the first terminal device to switch to a suitable cell or relay device based on the measurement results. When the first terminal device is in RRC idle state or RRC inactive state, after determining that the second terminal device is no longer a relay device for the first terminal device, the first terminal device determines to reselect a relay device so that it can switch to a suitable relay device.

[0013] In one possible implementation, a unicast connection exists between the first terminal device and the second terminal device. Before determining that the second terminal device is not a relay device of the first terminal device, the method further includes: the first terminal device sending first indication information to the second terminal device through the unicast connection, the first indication information being used to trigger the second terminal device to send a first message, the first message being used to measure a first signal quality, the first signal quality being the signal quality between the first terminal device and the second terminal device; the first terminal device receiving the first message; the first terminal device determining the first signal quality based on the first message; determining that the second terminal device is not a relay device of the first terminal device includes: if the first signal quality is less than a first threshold, the first terminal device determining that the second terminal device is not a relay device of the first terminal device.

[0014] In this embodiment, a unicast connection exists between the first terminal device and the second terminal device. The second terminal device provides relay services to the first terminal device. Therefore, if the first terminal device does not receive a second broadcast message from the second terminal device within a first duration after receiving the first broadcast message, it can trigger the second terminal device to send a first message through the first indication information, enabling data transmission between the first and second terminal devices. This allows the first terminal device to detect the first signal quality between the two devices based on the first message. The first terminal device then determines whether the second terminal device is suitable to continue providing relay services based on the first signal quality, thus more accurately determining whether the second terminal device is suitable as a relay device for the first terminal device. When the first signal quality is less than a first threshold, the first terminal device determines that the second terminal device is no longer suitable to provide relay services and can report this to the first network device to perform relay device switching according to the instructions of the first network device. When the first signal quality is not less than the first threshold, the first terminal device determines that the second terminal device is suitable to continue providing relay services, thus eliminating the need for relay device switching and avoiding unnecessary switching.

[0015] In one possible implementation, determining that the second terminal device is not a relay device of the first terminal device includes: the first terminal device, upon receiving second indication information from the second terminal device, determining that the second terminal device is not a relay device of the first terminal device, wherein the second indication information is used to indicate that the second terminal device does not provide relay services.

[0016] In this embodiment, the first terminal device can determine more quickly that the second terminal device is not a relay device of the first terminal device based on the second indication information sent by the second terminal device, without having to wait until it detects that no second broadcast message has been received within a first time period after receiving the first broadcast message before determining that the second terminal device is not a relay device of the first terminal device.

[0017] In one possible implementation, the second indication information is sent by the second terminal device when the second signal quality is less than a second threshold or greater than a third threshold, wherein the second signal quality is the signal quality between the second terminal device and the second network device.

[0018] In this embodiment of the application, if the second signal quality is less than the second threshold or greater than the third threshold, the second terminal device is not suitable for relay service. Therefore, sending the second indication information can promptly indicate to the first terminal device that the second terminal device does not provide relay service.

[0019] In one possible implementation, the first broadcast message includes a first identifier for identifying the second terminal device, which is generated by the second terminal device when it accesses the serving cell of the second terminal device.

[0020] In this embodiment, after receiving the first broadcast message, the first terminal device determines that the first broadcast message originated from the second terminal device based on the first identifier carried in the first broadcast message. After the second terminal device performs a cell handover, it can update the identifier carried in the broadcast message, allowing the first terminal device to treat the second terminal device after the cell handover as a new measurement object for recording, without needing to update the information of the serving cell of the second terminal device. This saves the workload of the first terminal device and improves the measurement efficiency of the first terminal device.

[0021] In one possible implementation, the first broadcast message includes first cell information of the second terminal device. After the first terminal device receives the first broadcast message sent by the second terminal device, the method further includes: the first terminal device determining whether the serving cell of the second terminal device has been switched based on the first cell information; if the serving cell of the second terminal device has been switched, the first terminal device sends a second message to the first network device, the second message including the first cell information.

[0022] In this embodiment, when the first terminal device determines that the serving cell of the second terminal device has been switched, it sends a second message to the first network device so that the first network device can update the information of the serving cell of the second terminal device in a timely manner, thereby avoiding the failure of the relay device of the first terminal device to switch to the second terminal device due to the first network device not updating the information of the serving cell of the second terminal device in a timely manner.

[0023] In one possible implementation, the first terminal device sends the second message to the first network device, including: the first terminal device determining whether the current serving cell of the second terminal device is a non-forbidden access cell based on the first cell information; and if the current serving cell of the second terminal device is a non-forbidden access cell, sending the second message to the first network device.

[0024] In this embodiment of the application, if the current serving cell of the second terminal device is a non-blocked access cell, and it is determined that the second terminal device can provide relay services to the first terminal device, then the first terminal device sends the second message to the first network device so that the first network device can update the information of the serving cell of the second network device in a timely manner.

[0025] In one possible implementation, the method further includes: if the current serving cell of the second terminal device is a prohibited access cell, the first terminal device deletes the measurement information corresponding to the second terminal device.

[0026] In this embodiment, when the serving cell of the second terminal device is a prohibited access cell, the first terminal device determines that the second terminal device cannot provide relay services to the first terminal device. Therefore, the first terminal device can delete the measurement information corresponding to the second terminal device from the measurement results of the first terminal device, so as to avoid including the measurement information of the second terminal device in the measurement results reported by the first terminal device. This can ensure that the reported measurement results include the appropriate measurement information of the terminal device, save the memory space occupied by the measurement results, and reduce the resources required by the first terminal device when reporting the measurement results.

[0027] In one possible implementation, the first cell information is included in the measurement information corresponding to the second device.

[0028] In this embodiment, when the first terminal device determines that the serving cell of the second terminal device has been switched, it can trigger a measurement reporting mechanism to report the measurement results of the first terminal device to the first network device. These measurement results include the measurement information of the second terminal device, which includes information about the first cell. This enables the first network device to update the measurement results of the first terminal device in a timely manner, allowing it to make reasonable switching decisions based on these results.

[0029] In one possible implementation, the first broadcast message includes first cell information of the second terminal device; after the first terminal device receives the first broadcast message sent by the second terminal device, the method further includes: the first terminal device receiving a third message from a first network device, the third message including second cell information of the second terminal device, the third message being used to instruct the relay device of the first terminal device to switch to the second terminal device; if the first cell information and the second cell information are inconsistent, the first terminal device determines that the handover has failed.

[0030] In this embodiment, the third message can be a handover command. For example, the first network device makes a handover decision based on the measurement results reported by the first terminal device, and instructs the first terminal device to handover to the second terminal device through this handover command. The first terminal device can handover to the second terminal device based on the second cell information. It is understood that the first terminal device can also receive the third message before receiving the first broadcast message, or receive the first broadcast message and the third message simultaneously. If the first cell information and the second cell information are inconsistent, it indicates that the serving cell of the second terminal device has already been handed over. Therefore, the first terminal device cannot handover to the second terminal device based on the second cell information, the handover is determined to have failed, and subsequent handover operations are not performed, thus avoiding the waste of resources caused by subsequent handover operations.

[0031] In one possible implementation, after the first terminal device determines that the handover has failed, the method further includes at least one of the following:

[0032] The first terminal device records a handover failure.

[0033] The first terminal device disconnects from the second terminal device;

[0034] The first terminal device performs Radio Resource Control (RRC) connection reconstruction.

[0035] In this embodiment, after determining that the handover has failed, the first terminal device can perform a handover failure measurement record to report the reason for the handover failure to the first network device. If a unicast connection exists with the second terminal device, this unicast connection is disconnected so that the first terminal device can establish a new unicast connection, ensuring the communication quality of the first terminal device and avoiding resource waste. After determining that the handover has failed, the first terminal device can also perform RRC connection reconstruction to restore the RRC signaling connection and avoid dropped connections.

[0036] In one possible implementation, the method further includes: the first terminal device receiving third indication information from the first network device, the third indication information being used to indicate the first duration.

[0037] In this embodiment of the application, the first duration can be determined by the first network device, which can facilitate the first network device to reasonably control the measurement and reporting behavior of the first terminal device.

[0038] In one possible implementation, before determining that the second terminal device is not a relay device of the first terminal device, the method further includes: when the first terminal device receives the first broadcast message, starting a first timer corresponding to the second terminal device, the runtime of the first timer being equal to the first duration; and when the first timer times out, the first terminal device determines that it has not received the second broadcast message within the first duration.

[0039] In this embodiment, the first terminal device can effectively monitor the second broadcast message sent by the second terminal device within a first duration by using a first timer. It should be understood that the first terminal device can receive broadcast messages from multiple terminal devices and maintain a timer for each of the multiple terminal devices, thereby effectively monitoring the broadcast messages of the multiple terminal devices to determine whether the multiple terminal devices are suitable as relay devices for the first terminal device.

[0040] In one possible implementation, the method further includes: if the first terminal device receives the second broadcast message within the first duration, then resetting the first timer.

[0041] In this embodiment of the application, upon receiving a second broadcast message, the first timer is reset to continue monitoring the discovery messages sent by the second terminal device, so that the first terminal device can promptly detect when the second terminal device stops sending discovery messages.

[0042] In one possible implementation, the first timer is controlled by the protocol layer of the first terminal device, the protocol layer including any one of the Radio Resource Control (RRC) layer, the physical layer, the Media Access Control (MAC) layer, and the discovery protocol layer.

[0043] In this embodiment, the first timer is controlled by the protocol layer of the first terminal device, which can effectively maintain the first timer.

[0044] Secondly, embodiments of this application provide a communication method, the method comprising: a first terminal device receiving a first broadcast message sent by a second terminal device; if no broadcast message is received from the second terminal device within a first time period after receiving the first broadcast message, the first terminal device performs any of the following: deleting measurement information corresponding to the second terminal device; determining a reselection relay device; and reporting the measurement result to a first network device.

[0045] In this embodiment, the first broadcast message and the second broadcast message can be discovery messages sent by the first terminal device at different times. These discovery messages instruct the second terminal device to provide relay services. Generally, the second terminal device periodically broadcasts discovery messages when providing relay services; it stops sending them when not providing relay services. Therefore, if the first terminal device does not receive the second broadcast message within a first time period after receiving the first broadcast message, it can be determined that the second terminal device is unsuitable as a relay device for the first terminal device. The first terminal device can determine subsequent operations based on its connection status. For example, if there is no unicast connection between the first and second terminal devices, i.e., the second terminal device does not provide relay services to the first terminal device, the first terminal device can delete the measurement information corresponding to the second terminal device from the measurement results. This avoids including measurement information corresponding to unsuitable terminal devices in the measurement results reported by the first terminal device, ensuring that the measurement results include measurement information of suitable terminal devices. When a unicast connection exists between the first terminal device and the second terminal device, and the first terminal device is in RRC connected state, the first terminal device can trigger measurement reporting to report measurement results to the first network device. This allows the first network device to instruct the first terminal device to perform relay device handover based on the measurement results, enabling the first terminal device to switch to a suitable cell or relay device. When a unicast connection exists between the first terminal device and the second terminal device, and the first terminal device is in RRC idle state or RRC inactive state, the first terminal device can determine to perform relay device reselection, allowing the first terminal device's relay device to switch to a suitable relay device.

[0046] In one possible implementation, a unicast connection exists between the first terminal device and the second terminal device. Before reporting the measurement result to the first network device, the method further includes: the first terminal device sending first indication information to the second terminal device through the unicast connection, the first indication information being used to trigger the second terminal device to send a first message, the first message being used to measure a first signal quality, the first signal quality being the signal quality between the first terminal device and the second terminal device; the first terminal device receiving the first message; and the first terminal device determining the first signal quality based on the first message.

[0047] In this embodiment, a unicast connection exists between the first terminal device and the second terminal device. If there is no data transmission in the unicast connection between the first terminal device and the second terminal device, and the first terminal device does not receive a second broadcast message within a first time period after receiving the first broadcast message, the first terminal device can trigger the second terminal device to send a first message through the first indication information, so that there is data transmission between the first terminal device and the second terminal device. This allows the first terminal device to detect the first signal quality between the first terminal device and the second terminal device based on the first message, and can accurately determine whether the second terminal is suitable to continue providing relay services to the first terminal device.

[0048] In one possible implementation, reporting the measurement result to the first network device includes: when the first signal quality is less than a first threshold, the first terminal device reports the measurement result to the first network device.

[0049] In this embodiment, if the first signal quality is less than a first threshold, and the first terminal device determines that the second terminal device is no longer suitable to provide relay services for the first terminal device, the first terminal device can report this to the first network device so that the first terminal device can switch to a suitable relay device according to the instructions of the first network device. It is understood that if the first terminal device determines that the second terminal device is suitable to continue providing relay services for the first terminal device when the first signal quality is not less than the first threshold, then there is no need to switch relay devices, thus avoiding unnecessary switching.

[0050] Thirdly, embodiments of this application provide a communication method, including:

[0051] A first terminal device receives a first broadcast message sent by a second terminal device, the first broadcast message including first cell information of the second terminal device; the first terminal device determines whether the serving cell of the second terminal device has been switched based on the first cell information; if the serving cell of the second terminal device has been switched, the first terminal device sends a second message to a first network device, the second message including the first cell information.

[0052] In this embodiment, when the first terminal device determines that the serving cell of the second terminal device has been switched, it sends a second message to the first network device so that the first network device can update the information of the serving cell of the second terminal device in a timely manner, thereby avoiding the failure of the relay device of the first terminal device to switch to the second terminal device due to the first network device not updating the information of the serving cell of the second terminal device in a timely manner.

[0053] In one possible implementation, the first terminal device sends the second message to the first network device, including:

[0054] The first terminal device determines whether the current serving cell of the second terminal device is a non-prohibited access cell based on the first cell information; if the current serving cell of the second terminal device is a non-prohibited access cell, the first terminal device sends the second message to the first network device.

[0055] In this embodiment of the application, if the current serving cell of the second terminal device is a non-blocked access cell, and it is determined that the second terminal device can provide relay services to the first terminal device, then the first terminal device sends the second message to the first network device so that the first network device can update the information of the serving cell of the second network device in a timely manner.

[0056] In one possible implementation, the method further includes:

[0057] If the current serving cell of the second terminal device is a prohibited cell, the first terminal device deletes the measurement information corresponding to the second terminal device.

[0058] In this embodiment, when the current serving cell of the second terminal device is a prohibited access cell, the first terminal device determines that the second terminal device cannot provide relay services to the first terminal device, and deletes the measurement information corresponding to the second terminal device from the measurement results of the first terminal device. This can ensure that the reported measurement results include the measurement information of the appropriate terminal device, while saving the memory space occupied by the measurement results and reducing the resources required by the first terminal device to report the measurement results.

[0059] In one possible implementation, the information of the first cell is included in the measurement information corresponding to the second device.

[0060] In this embodiment, when the first terminal device determines that the serving cell of the second terminal device has been switched, it can trigger a measurement reporting mechanism to report the measurement results of the first terminal device to the first network device. These measurement results include the measurement information of the second terminal device, which includes information about the first cell. This enables the first network device to update the measurement results of the first terminal device in a timely manner, allowing it to make reasonable switching decisions based on these results.

[0061] Fourthly, embodiments of this application provide a communication method, including:

[0062] A first terminal device receives a first broadcast message sent by a second terminal device, the first broadcast message including first cell information of the second terminal device; the first terminal device receives a third message from a first network device, the third message including second cell information of the second terminal device, the third message being used to instruct the relay device of the first terminal device to switch to the second terminal device; if the first cell information and the second cell information are inconsistent, the first terminal device determines that the handover has failed.

[0063] In this embodiment, the third message can be a handover command. For example, the first network device makes a handover decision based on the measurement results reported by the first terminal device, and instructs the first terminal device to handover to the second terminal device through this handover command. If the information of the first cell and the information of the second cell are inconsistent, the first terminal device cannot handover to the second terminal device based on the third message, and therefore the handover is determined to have failed. Subsequent handover operations are not performed, thus avoiding the waste of resources caused by subsequent handover operations.

[0064] In one possible implementation, after the first terminal device determines that the handover has failed, the method further includes at least one of the following:

[0065] The first terminal device records a handover failure.

[0066] The first terminal device disconnects from the second terminal device;

[0067] The first terminal device performs Radio Resource Control (RRC) connection reconstruction.

[0068] Fifthly, embodiments of this application provide a communication method, including:

[0069] The second terminal device measures the second signal quality, which is the signal quality between the second terminal device and the second network device. If the second signal quality is less than a second threshold or greater than a third threshold, the second terminal device sends a second indication message, which is used to indicate that the second terminal device does not provide relay service.

[0070] In this embodiment of the application, if the second signal quality does not meet the threshold condition, that is, if the second signal quality is less than the second threshold or the second signal quality is less than the third threshold, the second terminal device does not provide relay service. Therefore, it can send the second indication information to inform the surrounding terminal devices in a timely manner that the second terminal device does not provide relay service, thereby preventing the surrounding terminal devices of the second terminal device from reporting the second terminal device as a relay device.

[0071] Sixthly, embodiments of this application provide a communication apparatus for executing the method in the first aspect or any possible implementation thereof. The communication apparatus includes units capable of executing the method in the first aspect or any possible implementation thereof.

[0072] In a seventh aspect, embodiments of this application provide a communication apparatus for performing the method in the second aspect or any possible implementation thereof. The communication apparatus includes units capable of performing the method in the second aspect or any possible implementation thereof.

[0073] Eighthly, embodiments of this application provide a communication apparatus for performing the method in the third aspect or any possible implementation thereof. The communication apparatus includes units capable of performing the method in the third aspect or any possible implementation thereof.

[0074] Ninthly, embodiments of this application provide a communication apparatus for performing the method in the fourth aspect or any possible implementation thereof. The communication apparatus includes units capable of performing the method in the fourth aspect or any possible implementation thereof.

[0075] In a tenth aspect, embodiments of this application provide a communication apparatus for performing the method in the fifth aspect or any possible implementation thereof. The communication apparatus includes units capable of performing the method in the fifth aspect or any possible implementation thereof.

[0076] In the sixth, seventh, eighth, ninth, or tenth aspect, the aforementioned communication apparatus may include a transceiver unit and a processing unit. Further details regarding the transceiver unit and processing unit can be found in the apparatus embodiments shown below.

[0077] Eleventhly, this application provides a communication device including a processor that can execute computer execution instructions stored in a memory to execute the method shown in the first aspect or any possible implementation thereof, or to execute the method shown in the second aspect or any possible implementation thereof, or to execute the method shown in the third aspect or any possible implementation thereof, or to execute the method shown in the fourth aspect or any possible implementation thereof, or to execute the method shown in the fifth aspect or any possible implementation thereof.

[0078] In this embodiment of the application, during the execution of the above method, the process of sending information can be understood as a process of outputting information based on processor instructions. When outputting information, the processor outputs the information to the transceiver so that the transceiver can transmit it. After the information is output by the processor, it may undergo other processing before reaching the transceiver. Similarly, when the processor receives input information, the transceiver receives the information and inputs it into the processor. Furthermore, after the transceiver receives the information, it may need to undergo other processing before being input into the processor.

[0079] Unless otherwise specified, or unless their actual function or internal logic in the relevant description is contradicted, the sending and / or receiving operations involved by the processor can generally be understood as processor instruction output.

[0080] In implementation, the processor described above can be a processor specifically designed to execute these methods, or it can be a processor that executes computer instructions stored in memory to execute these methods, such as a general-purpose processor. For example, the processor can also be used to execute a program stored in memory, which, when executed, causes the communication device to perform the methods as shown in the first aspect or any possible implementation thereof.

[0081] In one possible implementation, the memory is located outside the aforementioned communication device.

[0082] In one possible implementation, the memory is located within the aforementioned communication device.

[0083] In this embodiment of the application, the processor and memory may also be integrated into a single device, that is, the processor and memory may be integrated together.

[0084] In one possible implementation, the communication device further includes a transceiver for receiving or sending messages, etc.

[0085] In a twelfth aspect, this application provides a communication device including a processing circuit and an interface circuit. The interface circuit is used to acquire or output data. The processing circuit is used to execute a corresponding method as shown in the first aspect or any possible implementation thereof, or to execute a corresponding method as shown in the second aspect or any possible implementation thereof, or to execute a corresponding method as shown in the third aspect or any possible implementation thereof, or to execute a corresponding method as shown in the fourth aspect or any possible implementation thereof, or to execute a corresponding method as shown in the fifth aspect or any possible implementation thereof.

[0086] In a thirteenth aspect, this application provides a computer-readable storage medium for storing a computer program that, when run on a computer, causes the method shown in the first aspect or any possible implementation thereof to be executed, or causes the method shown in the second aspect or any possible implementation thereof to be executed, or causes the method shown in the third aspect or any possible implementation thereof to be executed, or causes the method shown in the fourth aspect or any possible implementation thereof to be executed, or causes the method shown in the fifth aspect or any possible implementation thereof to be executed.

[0087] In a fourteenth aspect, this application provides a computer program product comprising a computer program or computer code that, when run on a computer, causes the method shown in the first aspect or any possible implementation thereof to be executed, or causes the method shown in the second aspect or any possible implementation thereof to be executed, or causes the method shown in the third aspect or any possible implementation thereof to be executed, or causes the method shown in the fourth aspect or any possible implementation thereof to be executed, or causes the method shown in the fifth aspect or any possible implementation thereof to be executed.

[0088] In a fifteenth aspect, this application provides a communication system, which includes a first terminal device and a second terminal device. The first terminal device is used to execute the method of any one of the first to fourth aspects described above, and the second terminal device is used to execute the fifth aspect or any possible implementation thereof. Attached Figure Description

[0089] The accompanying drawings used in the embodiments of this application are described below.

[0090] Figure 1 This is a schematic diagram of the architecture of a communication system provided in an embodiment of this application;

[0091] Figure 2 This is a schematic diagram of a control plane protocol architecture in a side-link communication provided in an embodiment of this application;

[0092] Figure 3 This is a schematic diagram of a protocol architecture for a discovery message provided in an embodiment of this application;

[0093] Figure 4A This is a schematic diagram of a discovery process provided in an embodiment of this application;

[0094] Figure 4B This is a schematic diagram of another discovery process provided in an embodiment of this application;

[0095] Figure 5A This is an interactive schematic diagram of a unicast connection establishment process provided in an embodiment of this application;

[0096] Figure 5B This is an interactive schematic diagram of another unicast connection establishment process provided in an embodiment of this application;

[0097] Figure 6 This is a schematic diagram of the structure of a communication system provided in an embodiment of this application;

[0098] Figure 7 This is a schematic diagram of a control plane protocol architecture provided in an embodiment of this application;

[0099] Figure 8 This is a schematic diagram of a user plane protocol architecture provided in an embodiment of this application;

[0100] Figure 9 This is a schematic diagram illustrating a scenario of switching from direct communication to non-direct communication, provided in an embodiment of this application.

[0101] Figure 10 This is an interactive schematic diagram of switching from direct communication to non-direct communication provided in an embodiment of this application;

[0102] Figure 11 This is a schematic diagram illustrating a scenario of switching from non-direct communication to direct communication provided in an embodiment of this application;

[0103] Figure 12 This is an interactive schematic diagram of switching from non-direct communication to direct communication provided in an embodiment of this application;

[0104] Figure 13 This is a schematic diagram of the architecture of a multipath relay communication system provided in an embodiment of this application;

[0105] Figure 14 This is a schematic diagram of a communication scenario provided in an embodiment of this application;

[0106] Figure 15A This is an interactive schematic diagram of a communication method provided in an embodiment of this application;

[0107] Figure 15B This is an interactive schematic diagram of another communication method provided in an embodiment of this application;

[0108] Figure 15C This is an interactive schematic diagram of another communication method provided in the embodiments of this application;

[0109] Figure 16 This is a schematic diagram of a communication method provided in an embodiment of this application;

[0110] Figure 17 This is an interactive schematic diagram of another communication method provided in the embodiments of this application;

[0111] Figure 18A This is an interactive schematic diagram of another communication method provided in the embodiments of this application;

[0112] Figure 18B This is an interactive schematic diagram of another communication method provided in the embodiments of this application;

[0113] Figure 19 This is an interactive schematic diagram of another communication method provided in the embodiments of this application;

[0114] Figure 20 This is an interactive schematic diagram of another communication method provided in the embodiments of this application;

[0115] Figure 21 This is an interactive schematic diagram of another communication method provided in the embodiments of this application;

[0116] Figure 22 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0117] Figure 23 This is a schematic diagram of another communication device provided in an embodiment of this application;

[0118] Figure 24 This is a schematic diagram of the structure of another communication device provided in the embodiments of this application. Detailed Implementation

[0119] The terms "first" and "second," etc., used in the specification, claims, and drawings of this application are only used to distinguish different objects and not to limit the order, sequence, priority, or importance of multiple objects. In the embodiments of this application, "multiple" refers to two or more. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices. Additionally, the character " / ," unless otherwise specified, generally indicates that the preceding and following objects are in an "or" relationship.

[0120] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0121] In this application, the terminal device can refer to user equipment (UE), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. The terminal device can also be a cellular phone, cordless phone, session initiation protocol (SIP) phone, wireless local loop (WLL) station, personal digital assistant (PDA), handheld device with wireless communication capabilities, computing device or other processing device connected to a wireless modem, vehicle-mounted device, wearable device, terminal device in a future 5G network, or terminal device in a future evolved public land mobile network (PLMN), etc. This application does not limit the scope of the terminal device to these specific types.

[0122] The network device in this application embodiment can be a device that connects terminal devices to a wireless network, specifically a base station. Base stations can include various forms, such as macro base stations, micro base stations (also called small stations), relay stations, access points, etc. Specifically, it can be an access point (AP) in a wireless local area network (WLAN), a base transceiver station (BTS) in a global system for mobile communications (GSM) or code division multiple access (CDMA), a base station (NodeB, NB) in wideband code division multiple access (WCDMA), an evolved Node B (eNB or eNodeB) in LTE, a relay station or access point, or a vehicle-mounted device, wearable device, or the next-generation Node B (gNB) in a 5G system, or a base station in a future PLMN network, etc.

[0123] The following describes the terminology used in the embodiments of this application.

[0124] 1. Sidelink (SL) communication

[0125] In wireless communication systems, terminal devices can communicate with each other via network devices, or they can communicate directly without network devices. Communication between terminal devices that transmits data directly without network devices can be called sidelink communication. For example, Figure 1 This is a schematic diagram of the architecture of a communication system provided in an embodiment of this application. In sidelink communication, the communication system may include at least two terminal devices. Figure 1 Two terminal devices, UE1 and UE2, are illustrated exemplarily. The interface between UE1 and UE2 is called the PC5 interface, and the communication link between UE1 and UE2 is called the sidelink. UE1 and UE2 can transmit data directly through the sidelink without going through the network, which can effectively reduce communication latency. For example, one application scenario for the sidelink communication system is vehicle-to-everything (V2X). In V2X, each vehicle is a terminal device, and data can be transmitted directly between vehicles through the sidelink.

[0126] For example, please see Figure 2 , Figure 2 This is a schematic diagram of the control plane protocol architecture in sidelink communication. Figure 2 As shown, UE1 and UE2 establish peer-to-peer protocol layers including Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), Media Access Control (MAC), and Physical Layer (PHY). On the control plane, UE1 encapsulates the RRC message generated by the RRC layer into a PDCP protocol data unit (PDU), which is then processed sequentially by the RLC, MAC, and PHY layers before being sent to UE2. UE2 then processes the PHY, MAC, and RLC layers sequentially to obtain the PDCP PDU.

[0127] For example, sidelink communication can support several communication methods, including broadcast, unicast, and multicast.

[0128] Broadcast communication can be similar to network devices broadcasting system information, where the sending terminal sends broadcast service data without encryption, and other terminal devices within the effective receiving range of the sending terminal and interested in the broadcast service can receive the broadcast service data.

[0129] Unicast communication requires two terminal devices to first establish a unicast connection, similar to the data communication between a terminal device and a network device after establishing an RRC connection. After establishing the unicast connection, the two terminal devices can communicate data based on a negotiated identifier; this data can be encrypted or unencrypted. Unlike broadcast communication, unicast communication requires two UEs to have established a unicast connection before they can communicate with each other.

[0130] Multicast communication refers to communication between all terminal devices within a communication group. In multicast communication, any terminal device within a communication group can receive or send multicast service data. For example, if a terminal device in a communication group sends multicast service data, all other terminal devices in the group can receive that multicast service data, and the sending terminal device can also receive multicast service data sent by other terminal devices in the group.

[0131] It should be understood that the communication methods supported by the sidelink described above are merely examples. The communication methods supported by the sidelink in this application are not limited to the three examples mentioned above, and may also include other new communication methods that emerge as technology develops. Therefore, the three communication methods shown above should not be construed as limiting the implementation of this application.

[0132] In sidelink communication, each sidelink communication corresponds to a pair of source layer-2 identifiers (L2 IDs) and destination L2 IDs. That is, a single sidelink communication requires one source L2 ID and one destination L2 ID. The aforementioned source L2 ID and destination L2 ID can be included in the subheader of the MAC protocol data unit (PDU) to enable data to be transmitted from the sending terminal to the correct receiving terminal.

[0133] For example, the aforementioned source L2 ID is assigned by the transmitting terminal (or source terminal). For instance, the transmitting terminal can select different source L2 IDs based on the communication type and standard. The communication type can include unicast, broadcast, and multicast communication, and the standard can include Long Term Evolution (LTE) or New Radio (NR). In some implementations, the transmitting terminal can periodically update the source L2 ID to protect the privacy of the sidelink service type, preventing it from being tracked and identified by other terminal devices.

[0134] For example, the aforementioned destination L2 ID can depend on the service type. The sending terminal can determine the correspondence between the destination L2 ID and broadcast, multicast, or unicast services based on pre-configuration, application layer server configuration, or core network configuration. For instance, during broadcast or multicast communication, the sending terminal can determine the destination L2 ID based on the broadcast or multicast service type. In unicast communication, the sending terminal first establishes a unicast connection with the receiving terminal (or destination terminal). For example, during the unicast connection establishment process, the sending terminal can select a default destination L2 ID, which is related to the service type of the unicast communication. After the unicast connection is established, the sending terminal can continue to use the default destination L2 ID for unicast communication.

[0135] For example, a terminal device that supports proximity-based service (ProSe) can discover nearby connectable terminal devices through a discovery process and establish a unicast connection with them so that subsequent communication can be carried out based on the unicast connection.

[0136] (1) Discovery process

[0137] The protocol stack for message discovery is as follows: Figure 3 As shown, UE1 and UE2 establish peer-to-peer protocol layers, including a discovery protocol layer, PDCP layer, RLC layer, MAC layer, and PHY layer. UE1's discovery message can be generated by the discovery protocol layer and processed sequentially by the PDCP layer, RLC layer, MAC layer, and PHY layer before being sent to UE2. UE2 then obtains the discovery message after processing by the PHY layer, MAC layer, RLC layer, and PDCP layer.

[0138] For example, the above discovery process can include two discovery models: a first discovery model and a second discovery model. For example, in the first discovery model, the terminal device can include an announcing UE and a monitoring UE. The announcing UE broadcasts a discovery message, which may carry a source L2 ID and a destination L2 ID. For example, the source L2 ID may be assigned by the announcing UE, and the destination L2 ID may be a predefined or pre-configured destination L2 ID. This discovery message can also be called an announcement message, which may carry information about the announcing UE. For example, the announcement message may include service type information, indicating the types of services that the announcing UE can provide, so that the monitoring UE can determine whether it needs the services provided by the announcing UE based on the announcement message. The monitoring UE monitors the announcement messages broadcast by the announcing UE. After receiving the announcement message broadcast by the announcing UE, the monitoring UE can determine whether it needs the services provided by the announcing UE based on the information carried in the announcement message, that is, whether to establish a unicast connection with the announcing UE. Figure 4A As shown, Figure 4A This application provides an example of a first discovery model, which may include multiple terminal devices. Figure 4A Five terminal devices are shown: UE1, UE2, UE3, UE4, and UE5. UE1 is the announcement terminal, while UE2, UE3, UE4, and UE5 are monitoring terminals. UE1 broadcasts an announcement message, and UE2, UE3, UE4, and UE5 monitor this message. Upon receiving the announcement message, UE2, UE3, UE4, and UE5 determine whether to establish a unicast connection with UE1 based on the information carried in the message.

[0139] For example, in the second discovery model, the terminal device may include a discoverer UE and a discoveree UE. The discoverer UE can broadcast a discovery message, which may carry a source L2 ID and a destination L2 ID. For example, the source L2 ID may be assigned by the discoverer UE, and the destination L2 ID may be a predefined or pre-configured destination L2 ID. This discovery message may also be called a solicitation message, which carries information about the service type required by the discoverer UE. The discoveree UE monitors the solicitation message broadcast by the discoverer UE and, upon receiving the solicitation message, determines whether it can provide the service required by the discoverer UE. If the discoverer UE determines that it can provide the service required by the discoverer UE, it sends a reply message to the discoverer UE. Figure 4B As shown, Figure 4B This application provides an example of a second discovery model, which may include multiple terminal devices. Figure 4B The diagram shows five terminal devices: UE1, UE2, UE3, UE4, and UE5. UE1 is the discovering terminal, while UE2, UE3, UE4, and UE5 are the discovered terminals. UE1 broadcasts a request message, which may include UE1's service requirements. UE2, UE3, UE4, and UE5 monitor this request message and, upon receiving it, determine whether to meet UE1's service requirements based on the information carried in the request message. For example, if UE2 and UE3 determine that UE1's service requirements are met, they send a reply message to UE1. After receiving the reply messages from UE2 and UE3, UE1 can choose either UE2 or UE3 to establish a unicast connection.

[0140] It should be understood that the two discovery models described above are merely examples, and the discovery models in the embodiments of this application are not limited to the two examples described above, but may also include other new discovery models that emerge as technology develops. Therefore, the two discovery models shown above should not be construed as limiting the implementation of this application.

[0141] (2) Unicast connection establishment

[0142] For example, during the unicast connection establishment process, the terminal device initiating the unicast connection establishment procedure can be called the initiating UE, such as the monitoring terminal in the first discovery model and the discovery terminal in the second discovery model. The peer of the initiating UE can be called the target UE, such as the announcement terminal in the first discovery model and the discovered terminal in the second discovery model. For example, after the discovery process, the initiating UE can determine the target UE from which a unicast connection can be established and initiate the unicast connection establishment procedure.

[0143] For example, after the discovery process, the initiating terminal can determine the source L2 ID for the unicast connection and the destination L2 ID of the target terminal. For instance, the destination L2 ID can be obtained based on the discovery process. After determining the source L2 ID and the destination L2 ID, the initiating terminal sends a direct communication request (DCR) message to the target terminal. This DCR message can carry the source L2 ID, the destination L2 ID, and user information. Upon receiving the DCR message, the target terminal saves the source L2 ID and the destination L2 ID and associates them with the current unicast connection context. For example, the target terminal can determine whether to accept the initiating terminal's unicast connection establishment request based on the user information included in the DCR message. If the target terminal decides to accept the unicast connection establishment request, it sends a direct communication accept (DCA) message to the initiating terminal (e.g., ...). Figure 5A (As shown). If the target terminal determines that it does not accept the unicast connection establishment request, it sends a unicast connection rejection (direct communication reject) message to the initiating terminal (e.g., Figure 5B (As shown).

[0144] 2. Measurement Reporting

[0145] For example, when a terminal device accesses a network device, the network device can send a configuration message to the terminal device. This configuration message may include information such as the measurement object, measurement reporting configuration, measurement interval (GAP), and measurement identifier (ID). The measurement GAP refers to the time period during which the terminal device leaves its current frequency point to measure at another frequency point. Based on this configuration message, the terminal device can measure the signal quality of its serving cell and surrounding cells. If the measured signal quality meets the measurement reporting conditions configured in the configuration message, the terminal device will report the measurement results to the network device. The network device can then instruct the terminal device to perform a cell handover based on the measurement results; that is, the network device can instruct the terminal device to perform a cell handover based on the signal quality of the serving cell and surrounding cells.

[0146] For example, the configuration message may include at least one measurement object. This at least one measurement object is the object to which the terminal device performs measurements, and each of the at least one measurement object may correspond to a measurement object ID. For example, the configuration message may include configuration information for the at least one measurement object. For instance, taking an NR measurement object as an example, the configuration information for this NR measurement object may include the synchronization signal and physical broadcast channel (PBCH) block (SSB) frequency, SSB subcarrier spacing, SSB-based measurement timing configuration (SMTC) configuration, whitelisted and blacklisted cells, cell frequency and identifier, etc. For example, if the SSB signal received by the terminal device satisfies the configuration information of the NR measurement object, then the SSB signal is determined to be a measurement object, meaning the terminal device can perform measurements on the SSB signal. For example, the configuration message mentioned above can be an RRC reconfiguration message, and the at least one measurement object can be included in the measurement object list (measObjectiveToAddModList) of the information element measconfig in the RRC reconfiguration message.

[0147] For example, the configuration message described above may include at least one measurement reporting configuration. Each of these configurations may include the criteria for triggering the reporting of a measurement report (i.e., the measurement reporting conditions) and the format of the measurement report. For example, each of these configurations corresponds to a measurement reporting event and is associated with a measurement object. For instance, the measurement report corresponding to an NR measurement object may include the measurement results of an SSB. For example, any one of these configurations has a configuration identifier (reportConfigId). For example, the configuration message may be an RRC reconfiguration message, and the at least one measurement reporting configuration is contained in the information element reportConfigToAddModList of the RRC reconfiguration message.

[0148] For example, depending on the trigger type, the at least one measurement reporting configuration can be divided into event-triggered reporting and periodic-triggered reporting.

[0149] For example, in a measurement reporting configuration triggered by an event, the configuration may include the event category, threshold value, duration for meeting the trigger condition, measurement quantity, and reference signal type of the corresponding measurement reporting event. The trigger quantity of the measurement reporting event is the indicator that triggers the event, and may include reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), and signal-to-interference-plus-noise ratio (SINR). When the terminal device measures that the trigger quantity meets the trigger threshold value of the measurement reporting event, it triggers the measurement reporting corresponding to that event. For example, during Uu interface handover, i.e., during the handover of the terminal device's serving cell, the trigger quantity of the measurement reporting event can be RSRP or RSRQ. For instance, the terminal device can determine whether to trigger the measurement reporting corresponding to the measurement reporting event by measuring the RSRP or RSRQ of the SSB signal.

[0150] For example, when a network device configures a measurement reporting system to trigger event-driven reporting for a terminal device, the network device can accordingly configure entry and exit thresholds for the measurement reporting event corresponding to this configuration. For instance, the entry threshold condition for measurement reporting event A1 is Ms - Hys > Thresh, and this condition lasts for a TimeToTriger period, where Ms is the measurement result of the serving cell, Hys represents the amplitude hysteresis of the measurement result, and Thresh is the threshold value. When the terminal device meets the entry threshold for this measurement reporting event, it records the measurement object corresponding to the event in its measurement variable (VarMeasReportList), forming a measurement entry for that object. The measurement variable records relevant measurement information that has triggered the measurement reporting condition. This measurement entry may contain a measurement ID, which can be associated with the measurement object that triggered the measurement reporting condition and its measurement result. After forming the measurement entry, the terminal device generates a measurement report, which includes the measurement result associated with the measurement ID or the measurement object, and reports this report to the network device. The measurement variable may include measurement entries corresponding to multiple measurement objects. The measurement report includes the measurement variable, and the format of the measurement report is determined by the measurement reporting configuration corresponding to the measurement reporting event. For example, the terminal device can report the above measurement report to the network device according to the measurement reporting configuration corresponding to the measurement reporting event. For instance, the terminal device can report the measurement report to the network device via a MeasurementReport message. The measurement report includes the measurement objects corresponding to the measurement entries in the terminal device's measurement variables and their measurement results.

[0151] For example, network device configuration for event-triggered reporting can include single-time event-triggered reporting and periodic event-triggered reporting. For example, for single-time event-triggered reporting, when the terminal device meets the entry threshold for the measurement reporting event and maintains this threshold for a certain period, the terminal device only triggers a single measurement report. For periodic event-triggered reporting, after the terminal device's measurement reporting is triggered, the terminal device starts a timer (reportInterval) between multiple measurements and a counter (reportAmount) for the number of measurements. Both the timer and the counter are configured by the network device. When the counter reaches the required number of reports, the terminal device stops reporting, completing the measurement reporting process corresponding to the measurement reporting event. When the counter is infinite, the terminal device periodically reports the measurement results.

[0152] For example, when a terminal device meets the exit threshold for a measurement reporting event, it can delete the corresponding measurement entry from the measurement variables. For instance, when a terminal device measures a measurement object and the exit threshold for a measurement reporting event is met, the terminal device can delete the measurement entry corresponding to that measurement object from the measurement variables. That is, in the next measurement reporting, the terminal device will no longer include the measurement result for that measurement object in the reported measurement results.

[0153] For example, when the network device is configured to periodically trigger measurement reporting to the terminal device, the terminal device can send measurement reports according to the reporting interval (reportInterval) configured by the network device. The measurement object corresponding to this measurement reporting configuration will be continuously recorded in the measurement variables of the terminal device, that is, the measurement result corresponding to the measurement object will be sent to the network device every time a measurement is reported.

[0154] For example, the configuration message further includes at least one measurement ID, which is used to associate a measurement object with a measurement reporting configuration. The terminal device can determine the correspondence between the measurement object and the measurement reporting configuration based on the measurement ID, and perform measurements on the measurement object according to the requirements of the corresponding measurement reporting configuration. For example, the at least one measurement ID can be included in the information element `measObjectiveToAddModList` of the RRC reconfiguration message.

[0155] 3. User-to-Network Relay (U2N Relay) technology

[0156] For example, U2N relay technology is a technology where a terminal device helps another terminal device communicate with a network device; or, in other words, U2N relay technology is a technology where a terminal device communicates with a network device via another terminal device. This U2N relay technology can also be called relay technology. In a U2N relay communication architecture, terminal devices can be divided into remote terminals (remote UEs) and relay terminals (relay UEs), whereby the remote terminal can communicate with the network device via the relay terminal. For example... Figure 6 As shown, Figure 6 This application provides an example of a U2N relay communication architecture. Figure 6 The diagram illustrates a remote terminal, a relay terminal, and a network device. The remote terminal communicates with the network device via the relay terminal. The remote terminal and the relay terminal communicate via a sidelink, with the corresponding interface referred to as PC5. The relay terminal and the network device are directly connected, i.e., they communicate via the Uu port. For example, the communication link between the relay terminal and the network device can be called a direct link.

[0157] For example, please see Figure 7 and Figure 8 ,in Figure 7 This is a schematic diagram of the control plane protocol architecture in a U2N relay communication architecture. Figure 8 This is a schematic diagram of the user plane protocol architecture in the U2N relay communication architecture.

[0158] For example, Figure 7 The control plane protocol stack architecture shown is as follows: Figure 8 The user plane protocol stack architecture shown is suitable for L2U2N relay scenarios. For the control plane, as... Figure 7 As shown, a PC5 interface is established between the remote terminal and the relay terminal, with end-to-end protocol layers including the Adaptation layer, RLC layer, MAC layer, and PHY layer. A Uu interface is established between the relay terminal and the network device (i.e., gNB), with end-to-end protocol layers including the Adaptation layer, RLC layer, MAC layer, and PHY layer. An N2 interface is established between the network device and the core network, with end-to-end protocol layers including the N2 interface protocol stack (N2Stack). Additionally, there are end-to-end protocol layers between the remote terminal and the network device, including the RRC layer and PDCP layer. Finally, there is an end-to-end protocol layer between the remote terminal and the core network (5G CoreNetwork, 5GC), including the non-access stratum (NAS) layer.

[0159] For the user plane, a PC5 interface is established between the remote terminal and the relay terminal, with end-to-end protocol layers including the adaptation layer, RLC layer, MAC layer, and PHY layer. A Uu interface is established between the relay terminal and the network device, with end-to-end protocol layers including the adaptation layer, RLC layer, MAC layer, and PHY layer. A GPRS tunneling protocol user plane (GTP-U) interface is established between the network device and the core network, with end-to-end protocol layers including the N3 Stack. Additionally, an end-to-end protocol layer between the remote terminal and the network device includes the Service Data Adaptation Protocol (SDAP) layer and the PDCP layer. An end-to-end protocol layer between the remote terminal and the core network includes the Internet Protocol (IP) layer.

[0160] For example, data packets from the remote terminal are relayed below the PDCP layer of the relay terminal; that is, the relay terminal maintains the relay RLC bearer, including the RLC layer, MAC layer, and PHY layer. Furthermore, in the U2N relay communication architecture, the control plane protocol architecture and user plane protocol architecture add an adaptation layer between the RLC layer and the PDCP layer. The main function of the adaptation layer is the multiplexing and splitting of radio bearers; that is, the adaptation layer supports the multiplexing of data from different PDCP entities onto a single RLC bearer, or the splitting of data from an RLC bearer onto different radio bearers.

[0161] For example, in an L3 U2N relay communication architecture, data packets from the remote terminal are relayed and forwarded at the Internet Protocol (IP) layer of the relay terminal. The IP layer is above the access stratum (AS) layer, specifically above the SDAP, PDCP, adaptation, RLC, MAC, and PHY layers. Therefore, there is an end-to-end IP, SDAP, PDCP, adaptation, RLC, MAC, and PHY layer between the remote terminal and the relay terminal, and an end-to-end IP, SDAP, PDCP, adaptation, RLC, MAC, and PHY layer between the relay terminal and the network device. There is no end-to-end protocol layer between the network device and the remote terminal.

[0162] For ease of description, in the embodiments of this application, the relay device that provides relay services to the remote terminal can be referred to as the serving relay device of the remote terminal, and the relay device that does not provide relay services to the remote terminal can be referred to as the peripheral relay device.

[0163] For example, a remote terminal can measure the signal quality of surrounding cells and the signal quality of surrounding relay equipment, and perform mobility management based on the measured signal quality, enabling the remote terminal to continuously enjoy network services while moving. For example, the mobility management of a remote terminal can include the following scenarios:

[0164] Scenario 1: Switching from direct-to-indirect communication

[0165] The handover from direct to indirect communication refers to a remote terminal switching from communicating directly with the network device to communicating with the network device through a relay device. For example, the remote terminal is in RRC connected state (RRC_CONNECTED). When the remote terminal is communicating directly with the network device, it can measure the signal quality of the current serving cell and the signal quality of the sidelinks with surrounding relay terminals according to the network device's configuration messages, and report the measurement results to the network device according to the configuration messages. The network device then instructs the remote terminal to switch to the target relay terminal based on the measurement results reported by the remote terminal, obtaining relay services through the target relay terminal and thus accessing the target base station where the target relay terminal is located. For example, when the remote terminal accesses the network device, the network device sends a configuration message to the remote terminal, which is used to configure the measurement reporting for the remote terminal. For example, the configuration message can configure the reporting conditions for triggering measurement reporting by the remote terminal. When the reporting conditions are met, the remote terminal triggers measurement reporting and reports the measurement results to the network device. For example, the above configuration message can specifically be an RRC Reconfiguration message.

[0166] For example, such as Figure 9 As shown, Figure 9 This is an example of a scenario where communication is switched from direct to indirect connection. Figure 9 Taking three terminal devices (UE1, UE2, and UE3) and two network devices (gNB1 and gNB2) as an example, UE1 is a remote terminal, and UE2 and UE3 are peripheral relay terminals of UE1. UE1 communicates directly with gNB1 via the Uu interface, UE2 communicates directly with gNB1, and UE3 communicates directly with gNB2. For example, UE2 and UE3 broadcast discovery messages. UE1 can measure the signal quality of the sidelink between itself and UE2 based on the discovery message broadcast by UE2, and measure the signal quality of the sidelink between itself and UE3 based on the discovery message broadcast by UE3. If the signal quality measured by UE1 meets the reporting conditions in the measurement configuration, UE1 triggers measurement recording and reporting, reporting the measurement results to gNB1. gNB1 can instruct UE1 to switch to UE2 or UE3 based on the measurement results reported by UE1, so that UE1 can access gNB1 or gNB2 through UE2 or UE3.

[0167] Exemplarily, in the scenario of direct communication to sidelink communication switching, the network device may configure a measurement reporting event Y (Event Y) for the remote terminal through this configuration message to define the measurement reporting behavior of the remote terminal. For example, the measurement reporting event Y may be defined as triggering a measurement report when the signal quality of the current serving cell of the remote terminal is less than a threshold Y1, and the signal quality of a surrounding optional relay terminal on the sidelink is greater than a threshold Y2.

[0168] Exemplarily, the entry condition of the measurement reporting event Y may be: (Mn + Hys < ThreshY1) and (Mr – Hys > ThreshY2), and the above conditions last for a duration of TimeToTrigger. Here, Mn is the signal quality of the serving cell; Mr is the signal quality of the surrounding relay terminal on the sidelink; Hys is the amplitude hysteresis of the measurement result; TimeToTrigger represents the duration of continuously satisfying the entry condition of the measurement reporting event, that is, the time hysteresis; ThreshY1 corresponds to the threshold Y1 in the measurement reporting event Y. When the remote terminal satisfies the conditions (Mn + Hys < ThreshY1) and (Mr – Hys > ThreshY2), and the duration of satisfying this condition is greater than or equal to the TimeToTrigger duration, it is determined that the entry condition of the above measurement reporting event is satisfied, and a measurement report is triggered.

[0169] Exemplarily, the exit condition of the measurement reporting event Y may be: (Mn + Hys > ThreshY1) or (Mr – Hys < ThreshY2), and the above conditions last for a duration of TimeToTrigger. The ThreshY2 corresponds to the threshold Y2. When the duration of the remote terminal satisfying the condition (Mn + Hys > ThreshY1) or (Mr – Hys < ThreshY2) is greater than or equal to the TimeToTrigger duration, the exit condition of the measurement reporting event Y is satisfied.

[0170] For example, the signal quality of the sidelink in the aforementioned measurement reporting event Y can be SD-RSRP, meaning the remote terminal obtains the signal quality of the sidelink with the surrounding relay terminal by receiving and measuring the discovery message sent by the surrounding relay terminal. When the terminal device meets the entry conditions for measurement reporting event Y, i.e., the signal quality of the serving cell of the terminal device is less than threshold Y1 and the SD-RSRP of the surrounding relay terminal is greater than threshold Y2, the remote terminal can perform measurement recording. That is, the remote terminal records the measurement object corresponding to the surrounding relay terminal into its measurement variables and performs measurement reporting according to the measurement reporting configuration corresponding to measurement reporting event Y. For example, the measurement results reported by the remote terminal may include the ID information of the surrounding relay terminal, the ID information of the serving cell of the surrounding relay terminal, and the signal quality of the sidelink between the remote terminal and the relay terminal.

[0171] For example, when the measurement result of the remote terminal meets the exit condition of the measurement reporting event Y, the remote terminal can delete the measurement object corresponding to the measurement reporting event Y from the measurement variables.

[0172] For example, after receiving the measurement results reported by the remote terminal, the network device makes a corresponding handover decision based on the measurement results, instructing the remote terminal to switch from direct communication to non-direct communication. That is, the remote terminal switches from communicating directly with the network device to communicating with the network device through a relay device. The specific process of switching from direct communication to non-direct communication is as follows: Figure 10 As shown below, Figure 10 The following steps will be explained:

[0173] S11, the remote terminal sends the measurement results to the source network device. The source network device is the network device that communicates with the remote terminal. The remote terminal can report measurements according to the measurement reporting configuration. The reported measurement results include the ID information of the surrounding relay terminals, the ID information of the serving cell of the surrounding relay terminals, and the signal quality of the sidelink of the surrounding relay terminals.

[0174] S12, the source network device determines the target network device and the target relay terminal based on the measurement results.

[0175] S13, the source network device sends a handover request message to the target network device.

[0176] S14, the target network device replies to the source network device with a handover acknowledgment (ACK) message.

[0177] S15, the target network device sends RRC configuration information to the target relay terminal. This RRC configuration message includes the air interface configuration required by the target relay terminal to provide relay services to the remote terminal, as well as the identification information of the remote terminal. After receiving the RRC configuration message, the target relay terminal can reply with a complete message to the target network device.

[0178] S16, the source network device sends a handover command (HO command) to the remote terminal. The handover command includes the configuration required for the remote terminal to access the target network device through the target relay terminal and the identification information of the target relay terminal device.

[0179] S17, a unicast connection is established between the remote terminal and the target relay terminal.

[0180] S18, the remote terminal replies to the target network device with an RRC reconfiguration complete message through the target relay terminal. The RRC reconfiguration complete message is used to indicate that the handover is complete.

[0181] It should be understood that during the handover from direct communication to non-direct communication, the source network device and the target network device can also be the same network device, i.e., a co-station handover can be performed. When performing a co-station handover, steps S13 and S14 do not need to be executed.

[0182] In this scenario, the remote terminal can measure the signal quality of the sidelink with the relay terminal by receiving and measuring the discovery message sent by the surrounding relay terminal. For example, the remote terminal can measure the signal quality of the sidelink with the surrounding relay terminal by measuring the RSRP of the discovery message sent by the relay terminal. The signal quality of the sidelink obtained by the remote terminal by measuring the RSRP of the discovery message sent by the surrounding relay terminal can be called SD-RSRP. In a U2N relay communication architecture, the relay terminal sends the discovery message when the signal quality on the Uu interface between it and the network device meets a threshold condition. That is, the relay terminal sends the discovery message when the signal quality on the Uu interface is between a minimum threshold and a maximum threshold. The minimum and maximum thresholds can be configured by the network device. If the relay terminal does not meet the above threshold conditions, the relay terminal does not provide relay service and therefore stops sending discovery messages. For example, the signal quality of the relay terminal on the Uu interface between it and the network device can be called the relay terminal's Uu-RSRP.

[0183] For a peripheral relay terminal, if its Uu-RSRP meets the aforementioned threshold condition, it periodically sends discovery messages. The remote terminal can then detect the peripheral relay terminal's SD-RSRP based on these discovery messages. If the peripheral relay terminal's SD-RSRP meets the entry condition for measurement reporting event Y, the peripheral relay terminal is added to the measurement variables, forming a corresponding measurement entry, and the corresponding measurement is reported. After a period of time, if the peripheral relay terminal's Uu-RSRP no longer meets the threshold condition, it stops sending discovery messages. The remote terminal no longer receives discovery messages from the peripheral relay terminal and cannot measure its SD-RSRP. In this case, the remote terminal cannot determine whether the peripheral relay terminal meets the entry or exit condition for measurement reporting event Y based on its SD-RSRP. Therefore, the measurement entry corresponding to the peripheral relay terminal remains in the remote terminal's measurement variables. Furthermore, the measurement entry still appears in the measurement results reported by the remote terminal when the measurement reporting is triggered again (e.g., when other measurement objects meet the entry conditions of their corresponding measurement reporting events). For example, even when surrounding relay terminals no longer provide relay services, the remote terminal still reports the measurement entry corresponding to that surrounding relay terminal, resulting in the reported measurement results including inappropriate relay terminals. Therefore, embodiments of this application provide a communication method that can solve the problem of inappropriate relay terminals appearing in the measurement results reported by the remote terminal. For details, please refer to... Figure 15A The relevant description in the document.

[0184] For a peripheral relay terminal, when the SD-RSRP of the peripheral relay terminal meets the entry condition of measurement reporting event Y, the remote terminal adds the peripheral relay terminal to the measurement variables, forming a measurement entry corresponding to the peripheral relay terminal, and performs the corresponding measurement reporting. If the peripheral relay terminal performs cell handover after the remote terminal adds the peripheral relay terminal to the measurement variables and performs measurement reporting, the peripheral relay terminal may fail to update the cell information of the peripheral relay terminal in a timely manner, which may lead to handover failure when the remote terminal performs relay device handover. For example, the network device sends a handover request to the network device before the cell handover of the peripheral relay terminal based on the cell information before the cell handover of the peripheral relay terminal, which is rejected by the network device before the cell handover of the peripheral relay terminal. In view of this, this application provides a communication method that enables the network device to update the cell information of the peripheral relay terminal in a timely manner, avoiding handover failure when the remote terminal's relay device handovers to the peripheral relay terminal due to the network device's failure to update the cell information of the peripheral relay terminal in a timely manner. For details, please refer to... Figure 18A Related descriptions.

[0185] Scenario 2: Switching from indirect to direct communication

[0186] The handover process from indirect to direct communication refers to the process by which a remote terminal switches from communicating with network devices through a relay terminal to communicating directly with the network devices. For example, the remote terminal is in RRC connection mode. When the remote terminal communicates with the network device through its serving relay terminal, it can measure the signal quality of the sidelink between itself and the serving relay terminal, as well as the signal quality of surrounding cells, according to the network device's configuration messages, and report the measurements according to the measurement reporting configuration in the configuration messages. For example... Figure 11 As shown, Figure 11 This is an example of a scenario for switching from non-direct communication to direct communication, provided in an embodiment of this application. Figure 11 The diagram illustrates two terminal devices (UE1 and UE2) and two network devices (gNB1 and gNB2), where UE1 is a remote terminal and UE2 is a relay terminal. UE1 communicates with gNB1 via UE2. UE2 communicates with gNB1 via a Uu interface, and UE1 communicates with UE2 via a sidelink. UE1 can receive configuration messages from gNB1 through UE2 and measure the signal quality of the sidelink between UE1 and UE2, as well as the signal quality of surrounding cells, based on these messages. For example, UE1 can measure the signal quality of cells under gNB1 and gNB2. When the measured signal quality meets the reporting conditions, UE1 reports the measurement results to gNB1. gNB1 can then instruct UE1 to handover to a suitable cell based on the reported measurement results. For example, gNB1 can instruct UE1 to handover to a cell under gNB2.

[0187] In scenarios where communication transitions from indirect to direct, network devices can configure a measurement reporting event X (Evnet X) for remote terminals to define their measurement reporting behavior. For example, the measurement reporting event X can be defined as triggering measurement reporting when the signal quality of the sidelink between the remote terminal and the serving relay terminal is less than a threshold X1 and the signal quality of surrounding cells is greater than a threshold X2.

[0188] Exemplarily, the entry condition for the measurement reporting event X may be: (Mr + Hys < ThreshX1) and (Mn + Offset – Hys > ThreshX2), and the above conditions persist for a duration of TimeToTrigger. Where Mr is the signal quality of the current serving relay terminal; Mn is the signal quality of the surrounding cells; Hys is the amplitude hysteresis of the measurement result; TimeToTrigger represents the duration for continuously meeting the event entry condition, that is, the time hysteresis; Offset represents the sum of the frequency offsets of the neighboring cells. Offset is the sum of Ofn and Ocn, where Ofn is the specific frequency offset of the measurement object in the cell and Ocn is the cell-level offset. ThreshX1 corresponds to the threshold X1 in the measurement reporting event X. When the remote terminal meets the conditions (Mr + Hys < ThreshX1) and (Mn + Offset – Hys > ThreshX2), and the duration for meeting these conditions is greater than or equal to the duration of TimeToTrigger, the entry condition for this measurement reporting event is met, triggering a measurement report.

[0189] Exemplarily, the exit condition for the measurement reporting event X may be: (Mr + Hys > ThreshX1) or (Mn + Offset – Hys < ThreshX2), and the above conditions persist for a duration of TimeToTrigger. ThreshX2 corresponds to the threshold X2 in the measurement reporting event X. When the duration for which the remote terminal meets the condition (Mr + Hys > ThreshX1) or (Mn + Offset – Hys < ThreshX2) is greater than or equal to the duration of TimeToTrigger, the exit condition for this measurement reporting event Y is met.

[0190] Exemplarily, the signal quality of the sidelink between the remote terminal and the serving relay terminal in the above measurement reporting event X may be SL-RSRP, that is, the remote terminal can obtain the signal quality of the sidelink with the relay terminal by receiving and measuring the data sent by the serving relay terminal. In some implementations, when there is no data transmission between the remote terminal and the serving relay terminal, the remote terminal can also obtain SD-RSRP by measuring the discovery message sent by the serving relay terminal, and use this SD-RSRP as the signal quality of the sidelink between the remote terminal and the serving relay terminal.

[0191] For example, when the signal quality of the sidelink between the remote terminal and the serving relay terminal, as well as the signal quality of the surrounding cells, meet the entry conditions for the aforementioned measurement reporting event X, the remote terminal performs measurement recording. That is, the remote terminal records the measurement object corresponding to measurement reporting event X into a variable, and performs measurement reporting according to the measurement reporting configuration of measurement reporting event X, reporting the measurement results to the network device. For example, the measurement results include the ID information of the surrounding cells and the signal quality of the surrounding cells.

[0192] For example, when the measurement result of the remote terminal meets the exit condition of the measurement reporting event X, the remote terminal deletes the measurement object corresponding to the measurement reporting event X from the measurement variables.

[0193] For example, after receiving the measurement results reported by the remote terminal, the network device makes a corresponding handover decision based on the measurement results, instructing the remote terminal to switch from non-direct communication to direct communication. That is, the remote terminal switches from communicating with the network device through a relay device to communicating directly with the network device. The specific process of switching from non-direct communication to direct communication is as follows: Figure 12 As shown below, Figure 12 The following steps will be explained:

[0194] S21, the remote terminal sends the measurement results to the source network device through the serving relay terminal. The measurement results include the ID information of the surrounding cells and the signal quality of the surrounding cells.

[0195] S22, the source network device determines the target network device based on the measurement results.

[0196] S23, the source network device sends a handover request message to the target network device.

[0197] S24, the target network device replies with a handover ACK message to the source network device.

[0198] S25, the source network device sends a handover command to the remote terminal through the serving relay terminal device. The handover command includes the configuration required for the remote terminal to access the target network device.

[0199] S26, the remote terminal accesses the target network device based on the handover command. For example, the remote terminal can access the target network device via random access.

[0200] S27, the remote terminal replies to the target network device with an RRC reconfiguration complete message, which indicates that the handover is complete.

[0201] In step S28, the source network device sends an RRC reconfiguration message to the serving relay terminal. This RRC configuration message instructs the serving relay terminal to release the configurations associated with the remote terminal, such as the air interface configurations related to the remote terminal. Accordingly, after S28, the relay device also replies to the source network device with an RRC reconfiguration complete message.

[0202] S29, the serving relay terminal releases the unicast connection with the remote terminal. It should be understood that this unicast connection can also be released by the remote terminal.

[0203] It should be understood that during the handover from non-direct communication to direct communication, the source network device and the target network device can also be the same network device, i.e., a co-station handover can be performed. When performing a co-station handover, steps S23 and S24 do not need to be executed.

[0204] In this scenario, the remote terminal can measure the signal quality of the sidelink with the serving relay terminal by receiving and measuring data transmitted by the serving relay terminal based on a unicast connection. For example, the remote terminal can measure the signal quality of the sidelink with the serving relay terminal by measuring the RSRP of the data transmitted by the serving relay terminal. The signal quality of the sidelink obtained by the remote terminal through measuring the RSRP of the data transmitted by the serving relay terminal can be referred to as SL-RSRP. The remote terminal can also measure the signal quality of the sidelink with the serving relay terminal based on a discovery message broadcast by the serving relay terminal.

[0205] For example, when there is no data transmission in the unicast connection between the remote terminal and the serving relay terminal, the remote terminal can detect the SD-RSRP of the serving relay terminal. For instance, if the SD-RSRP of the serving relay terminal does not meet the threshold condition at time T, it stops sending discovery messages. Furthermore, before time T, the SD-RSRP of the serving relay terminal does not meet the entry condition for measurement reporting event X. The remote terminal does not receive the discovery message sent by the serving relay terminal and cannot determine whether the SD-RSRP of the serving relay terminal meets the entry condition for measurement reporting event X. Therefore, the remote terminal will not trigger measurement reporting, but at this time, the serving relay terminal is no longer suitable as a relay device for the remote terminal. The communication method provided in this application embodiment can determine whether the serving relay terminal is suitable to continue serving as a relay device for the remote terminal, and trigger measurement reporting when the serving relay terminal is no longer suitable to continue serving as a relay device for the remote terminal, so that the relay device of the remote terminal can be switched to a suitable relay terminal in a timely manner. For a detailed implementation of this communication method, please refer to [link to relevant documentation]. Figure 15B The relevant description in the document.

[0206] Scenario 3: Switching from indirect communication to indirect communication

[0207] For example, a handover from indirect communication to indirect communication refers to a remote terminal switching from one indirect communication to another, i.e., a range relay device in the remote location switching from one relay terminal to another. For example, the remote terminal is in a connected state. For example, the remote terminal can communicate with the network device through the currently serving relay terminal and receive configuration messages from the network device through the currently serving relay terminal. For example, the configuration message can configure the remote terminal to meet measurement reporting conditions. The remote terminal can measure the signal quality of the lateral link between itself and the currently serving relay terminal, as well as the signal quality of the lateral link between itself and surrounding relay terminals, according to the configuration message. When the signal quality measured by the remote terminal meets the measurement reporting conditions configured in the configuration message, for example, if the lateral link signal quality of the serving relay terminal is less than a first preset threshold, and the measured lateral link signal quality of the surrounding relay terminals is greater than a second preset threshold, the remote terminal triggers measurement reporting and reports the measurement results to the network device. The first and second preset thresholds can be set by the network device. For example, a network device can determine a target relay terminal based on the measurement results reported by the remote terminal and instruct the remote terminal to switch from the current serving relay terminal to the target relay terminal. It should be understood that the current serving relay terminal and the target relay terminal can communicate with one network device or with different network devices.

[0208] Understandably, the specific process for switching from non-direct communication to non-direct communication can be found in the relevant descriptions of switching from direct communication to non-direct communication, and vice versa. It will not be detailed here.

[0209] Scenario 4: Selection and Reselection of Relay Terminals

[0210] For example, when a remote terminal is in an idle or inactive state, it can select and reselect a relay terminal. For instance, when the remote terminal is in direct communication with a network device, if the remote terminal detects that the signal quality of the current serving cell is less than a third preset threshold, or receives an indication from the network device, the remote terminal can select a relay terminal. The third preset threshold can be configured by the network device, and the indication is used to instruct the remote terminal to select a relay terminal. When the remote terminal is indirectly communicating with the network device through a serving relay terminal, if the remote terminal meets the triggering conditions for relay terminal reselection, the remote terminal will reselect a relay terminal. The triggering conditions for relay terminal reselection may include one or more of the following: the signal quality of the sidelink between the remote terminal and the current relay terminal is less than a fourth preset threshold, receiving an indication from the network device, or sidelink communication failure. The fourth preset threshold can be configured by the network device, and the indication is used to instruct the remote terminal to reselect a relay terminal.

[0211] In this scenario, the remote terminal can detect the SD-RSRP of the serving relay terminal based on the discovery message broadcast by the serving relay terminal to determine whether to perform relay terminal reselection. If the serving relay terminal stops sending discovery messages because its Uu-RSRP does not meet the threshold condition, the remote terminal cannot detect the SD-RSRP of the serving relay terminal and cannot determine whether relay device reselection is necessary, thus preventing the remote terminal from performing relay terminal reselection in a timely manner. Therefore, this application provides a communication method that enables the remote terminal to perform relay terminal reselection in a timely manner. The specific implementation of this communication method can be found in [link to relevant documentation]. Figure 15C The relevant description in the document.

[0212] It should be understood that the handover scenarios described above—from direct to non-direct communication, from non-direct to direct communication, and from non-direct to non-direct communication—are merely examples. In practical applications, the handover of remote terminals may not be limited to the scenarios shown above. For instance, a remote terminal can simultaneously measure the signal quality of the sidelink between itself and surrounding relay devices, as well as the signal quality of surrounding cells. If the measured signal quality meets the reporting conditions, the terminal can report the measurement results to the network device. The network device can then instruct the remote terminal to handover to the target relay device or the target cell based on the measurement results reported by the remote terminal. Therefore, the handover scenarios described above should not be construed as limiting the scope of this application.

[0213] For example, in the first discovery model, relay terminals that meet the threshold conditions of the aforementioned Uu-RSRP can periodically broadcast announcement messages (i.e., discovery messages), and remote terminals monitor and receive these announcement messages from surrounding relay terminals. In the second discovery model, remote terminals can periodically broadcast request messages, which indicate that the remote terminal needs relay services. After monitoring and receiving the request message, if the aforementioned threshold conditions are met, surrounding relay terminals send a reply message (discovery message) to the remote terminal, indicating that the relay terminal can access relay services.

[0214] For example, the discovery message (announcement message or reply message) sent by the relay terminal may include the source L2 ID, the destination L2 ID, and information about the serving cell of the relay terminal, such as the identity document (ID) information of the serving cell.

[0215] 4. Multi-path relaying

[0216] In a multi-path relaying communication architecture, a remote terminal can have multiple connections with a network device. Specifically, a remote terminal can simultaneously establish multiple non-direct communication connections with the network device, meaning it can establish connections through multiple relay terminals at the same time. For example, a remote terminal can connect to the network device via a direct Uu port link while also establishing connections through relay terminals. Figure 13 As shown, Figure 13 As an example of a multi-path relaying architecture, Figure 13 Taking a remote terminal (UE1), a relay terminal (UE2), and a network device (gNB1) as an example, UE1 can communicate directly with gNB1 via the Uu port, and can also communicate indirectly with gNB1 via UE2. It can be understood that UE1 can have multiple indirect communication connections with the network device through multiple relay terminals. Figure 13 Only one non-direct communication connection is shown. It should be understood that in a multi-path relaying communication architecture, a remote terminal can establish connections with different network devices or with the same network device through direct and non-direct communication, and this application does not impose any limitations.

[0217] Figure 14 An example of a communication scenario using a U2N relay architecture is shown. This communication scenario may include at least one remote terminal, at least one relay terminal, and at least one network device. Figure 14 Taking two remote terminals, three relay terminals, and two network devices as an example, the two remote terminals are Remote UE1 and Remote UE2, the three relay terminals are Relay UE1, Relay UE2, and Relay UE3, and the two network devices are gNB1 and gNB2. Remote UE1 communicates directly with gNB1 via the Uu interface, Relay UE1 communicates directly with gNB1 via the Uu interface, Relay UE2 communicates directly with gNB2 via the Uu interface, and Relay UE3 communicates directly with gNB2 via the Uu interface. Remote UE2 communicates with gNB2 through Relay UE3. Remote UE2 and Relay UE3 are connected via a sidelink.

[0218] For example, Relay UE1, Relay UE2, and Relay UE3 can periodically broadcast discovery messages. Remote UE1 can measure the signal quality with Relay UE1, Relay UE2, and Relay UE3 based on the discovery messages broadcast by Relay UE1, Relay UE2, and Relay UE3. When the signal quality of any relay terminal meets the reporting conditions in its corresponding measurement reporting configuration, Remote UE1 triggers the measurement recording and reporting for that relay terminal, reporting the measurement results to gNB1. For example, if the signal quality of Relay UE1 meets the reporting configuration in its corresponding measurement reporting configuration, Remote UE1 records and reports the measurement results for Relay UE1. gNB1 can instruct the serving relay device of Remote UE1 to switch to Relay UE1, Relay UE2, or Relay UE3 based on the measurement results reported by Remote UE1.

[0219] For example, Remote UE2 can measure the signal quality of the sidelink between itself and Relay UE3, the signal quality of surrounding relay terminals, and the signal quality of surrounding cells. When there is no data transmission between Remote UE2 and Relay UE3, Remote UE2 can measure the signal quality of the sidelink between itself and Relay UE3 based on the discovery message broadcast by Relay UE3, and report the measurement when the signal quality of the sidelink between itself and Relay UE3 meets the reporting conditions.

[0220] It should be noted that, Figure 14 The communication scenario illustrated is merely an example and does not limit the application scenarios applicable to the embodiments of this application. It should be understood that the use of a relay terminal in the embodiments of this application is solely for descriptive purposes and does not imply that the solution in the embodiments of this application is only applicable to U2N relay scenarios. In the embodiments of this application, a relay terminal can refer to any node or device with relay functionality. The communication method provided in the embodiments of this application can be applied to various communication systems including relay devices, such as NR systems, LTE systems, LTE-A systems, Worldwide Interoperability for Microwave Access (WiMAX), or Wireless Local Area Networks (WLAN), etc. For example, the communication method provided in the embodiments of this application can be applied to scenarios where measurement signals undergo sudden changes. For example, scenarios where the relay device suddenly stops transmitting measurement information or suddenly transmits measurement information.

[0221] Please see Figure 15A , Figure 15A This is a flowchart illustrating a communication method provided in an embodiment of this application. This communication method can be applied to, for example... Figure 14 The communication scenario shown. (As shown in the image) Figure 15A As shown, the communication method includes, but is not limited to, the following steps.

[0222] 1501, the second terminal device sends a first broadcast message, and correspondingly, the first terminal device receives the first broadcast message.

[0223] For example, the first broadcast message described above can be a discovery message broadcast by the second terminal device. For example, the first broadcast message is used to indicate that the second terminal device is capable of providing relay services. When providing relay services, the second terminal device can periodically broadcast discovery messages to indicate that it is capable of providing relay services.

[0224] For example, after receiving the first broadcast message, the first terminal device can measure the signal quality of the first broadcast message. For instance, after receiving the first broadcast message, the physical layer of the first terminal device measures the signal strength of the first broadcast message to obtain an L1 measurement result, and submits the L1 measurement result to the RRC layer. The RRC layer performs L3 filtering on the L1 measurement result to obtain the signal quality SD-RSRP of the first broadcast message. For example, when the first terminal device is in an RRC connected state, the first terminal device can perform corresponding measurement recording and measurement reporting based on the SD-RSRP. Alternatively, when the first terminal device is in an RRC idle state or inactive state, the first terminal device can select and reselect relay devices based on the SD-RSRP.

[0225] 1502, if the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message, then it is determined that the second terminal device is not a relay device of the first terminal device.

[0226] For example, the second broadcast message can be a discovery message broadcast by the second terminal device. For example, the second terminal device can periodically send discovery messages, which are used to instruct the second terminal device to provide relay services. The discovery message can include the aforementioned first and second broadcast messages; that is, the first and second broadcast messages are discovery messages sent by the second terminal device at different times.

[0227] If the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message, it indicates that the second terminal device is not suitable to provide relay services for the first terminal device. Therefore, the first terminal device determines that the second terminal device is not a relay device for the first terminal device, that is, the first terminal device does not use the second terminal device as a relay device for the first terminal device.

[0228] For example, if the conditions for sending a discovery message are not met, the second terminal device stops sending the discovery message. For instance, if the signal quality between the second terminal device and the second network device does not meet a threshold condition, the second terminal device stops broadcasting the discovery message. For example, the signal quality between the second terminal device and the second network device can be the Uu-RSRP of the second terminal device. If the Uu-RSRP of the second terminal device is less than a minimum threshold or greater than a maximum threshold, the second terminal device does not provide relay service and therefore stops sending the discovery message. If the first terminal device does not receive a second broadcast message from the second terminal device within a first duration after receiving the first broadcast message, it determines that the second terminal device has stopped sending the discovery message, and therefore the first terminal device determines that the second terminal device is not a relay device for the first terminal device.

[0229] For example, determining in step 1502 that the second terminal device is not a relay device for the first terminal device can include the following situations:

[0230] Scenario 1: The second terminal device is not a relay device for the first terminal device at the current moment.

[0231] If the second terminal device is not a relay device for the first terminal device at the current moment, the first terminal device's determination that the second terminal device is not a relay device for the first terminal device can be understood as the first terminal device determining that it will not use the second terminal device as a relay device for the first terminal device after the current moment, that is, it will not use the second terminal device as a backup relay device.

[0232] Scenario 2: The second terminal device is a relay device for the first terminal device at the current moment.

[0233] When the second terminal device is currently acting as a relay device for the first terminal device, the first terminal device's determination that the second terminal device is not its relay device can be understood as the first terminal device determining that the second terminal device will no longer act as its relay device after the current moment; that is, the first terminal device will not continue to use the second terminal device as its relay device after the current moment. In this case, a unicast connection exists between the first and second terminal devices, and the second terminal device provides relay services to the first terminal device based on this unicast connection. After determining that the second terminal device is no longer its relay device, the first terminal device can release the unicast connection between the first and second terminal devices and switch the first terminal device's relay device to another terminal device, so that the second terminal device no longer provides relay services to the first terminal device. For example, when the first terminal device is in an RRC connection state, after determining that the second terminal device is no longer its relay device, the first terminal device reports the measurement results to the first network device so that, according to the instructions of the first network device, the first terminal device can switch the first terminal device's relay device to another terminal device, so that the second terminal device no longer acts as the first terminal device's relay device. When the first terminal device is in an RRC idle state or an RRC inactive state, after determining that the second terminal device is not a relay device for the first terminal device, the first terminal device determines to reselect a relay device to switch the relay device of the first terminal device to another terminal device, so that the second terminal device is no longer a relay device for the first terminal device.

[0234] In this embodiment, the first broadcast message and the second broadcast message can be discovery messages sent by the first terminal device at different times. These discovery messages instruct the second terminal device to provide relay services. Generally, the second terminal device periodically broadcasts discovery messages when providing relay services. When not providing relay services, the second terminal device stops sending discovery messages. Therefore, if the first terminal device does not receive the second broadcast message within a first duration after receiving the first broadcast message, it can determine that the second terminal device is not a relay device for the first terminal device. This allows the first terminal device to identify unsuitable terminal devices and more accurately determine whether the second terminal device is suitable as a relay device for the first terminal device. It is understood that if the first terminal device receives the second broadcast message within a first duration after receiving the first broadcast message, the first terminal device can determine whether the second terminal device is suitable as a relay device for the first terminal device by measuring the signal quality of the first and second broadcast messages.

[0235] In some embodiments, the first terminal device may broadcast a discovery message, and step 1501 may be replaced by: the first terminal device sending a first broadcast message, which instructs the first terminal device to request relay service. Step 1502 may be replaced by: if no reply message is received from the second terminal device within a second time period after sending the first broadcast message, then the second terminal device is determined not to be a relay device for the first terminal device. For example, the first broadcast message is a request message sent by the first terminal device. When the first terminal device needs relay service, it may periodically send request messages, which instruct the first terminal device to request relay service. After receiving the request message, the second terminal device, if it can provide relay service, sends a reply message to the first terminal device. If the first terminal device does not receive a reply message from the second terminal device within a second time period after sending the discovery message, it indicates that the second terminal device is not suitable to provide relay service for the first terminal device, and therefore the first terminal device determines that the second terminal device is not a relay device for the first terminal device.

[0236] For example, regarding the aforementioned first duration, the embodiments of this application provide the following implementation methods:

[0237] Implementation method 1: The first duration is determined by the first network device.

[0238] For example, before step 1502, Figure 15A The communication method shown may also include the following steps:

[0239] The first terminal device receives third indication information from the first network device, the third indication information being used to indicate the first duration.

[0240] For example, the first network device is the network device that connects the first terminal device to the network. The first duration is configured by the first network device. The first network device can determine the first duration based on the network implementation and actual conditions, and indicate the first duration through the third indication information. For example, the first network device can determine the first duration based on actual conditions, and indicate through the third indication information that if the first terminal device does not receive a discovery message sent by the second terminal device within the first duration, then it determines that the second terminal device is not a relay device for the second terminal device. After receiving the third indication information, the first terminal device determines the first duration based on the third indication information. For example, the first duration is longer than the period during which the second terminal device broadcasts the discovery message. As an optional approach, the network application layer, such as the discovery layer, indicates the period duration during which the relay device sends the discovery message to the first network device, and the first network device can also determine the first duration based on the network indication.

[0241] Implementation Method Two: The aforementioned first duration can be determined by the first terminal device. The first terminal device determines the first duration based on messages previously received from the second terminal device. Before step 1502, Figure 15A The communication method shown may also include the following steps:

[0242] The first terminal device receives a third broadcast message sent by the second terminal device and determines the first duration based on the time interval between receiving the first broadcast message and the third broadcast message.

[0243] For example, the third broadcast message is a discovery message broadcast by the second terminal device. The first broadcast message and the third broadcast message are discovery messages received at different times. The first terminal device can determine the first duration based on the time interval between receiving the discovery messages sent by the second terminal device; that is, the first terminal device can determine the first duration based on the time interval between receiving the first broadcast message and receiving the third broadcast message. For example, the first broadcast message and the second broadcast message can be two discovery messages sent consecutively by the second terminal device. For example, the first duration can be greater than the time interval.

[0244] Implementation Method 3: The aforementioned first duration is determined by the second terminal device. Before step 1502, Figure 15A The communication method shown may also include the following steps:

[0245] The first terminal device receives a fourth instruction information from the second terminal device, which is used to indicate the first duration.

[0246] For example, the second terminal device can periodically send discovery messages when the conditions for sending discovery messages are met. In some implementations, the second terminal device can determine the first duration based on the period at which it sends discovery messages, and indicate the first duration to the first terminal device through the fourth indication information. After receiving the fourth indication information, the first terminal device determines the first duration based on the fourth indication information. In other implementations, the fourth indication information may include information about the period at which the second terminal sends the discovery messages. After receiving the fourth indication information, the first terminal device determines the period at which the second terminal sends discovery messages, and determines the first duration based on the period at which the second terminal sends discovery messages. For example, the first duration is longer than the period at which the second terminal device sends discovery messages.

[0247] In this embodiment of the application, the first duration can be determined by any one of the first network device, the first terminal device, and the second terminal device. The first duration is longer than the period during which the second terminal device sends the discovery message. For example, the first duration can be the period during which two second terminal devices send discovery messages. This can avoid the situation where the first terminal device fails to receive the second broadcast message sent by the second terminal device on time due to network delay, and can improve the fault tolerance rate.

[0248] In one possible implementation, before determining in step 1502 that the second terminal device is not a relay device for the first terminal device, the above communication method further includes the following steps:

[0249] When the first terminal device receives the first broadcast message, it starts a first timer corresponding to the second terminal device, and the running time of the first timer is equal to the first duration; if the first timer times out, the first terminal device determines that it did not receive the second broadcast message within the first duration.

[0250] For example, the first timer is a timer configured by the first terminal device for the second terminal device, used to enable the first terminal device to monitor discovery messages sent by the second terminal device during the runtime of the first timer. For example, the first broadcast message includes a first identifier of the second terminal device, which is used to identify the second terminal device. For instance, after receiving the first broadcast message, the first terminal device determines that the first broadcast message originates from the second terminal device based on the first identifier carried in the first broadcast message. For example, the first identifier is associated with the first timer. After receiving the first broadcast message, the first terminal device starts the first timer and monitors the second broadcast message sent by the second terminal device during the runtime of the first timer. The second broadcast message includes the first identifier. For example, the first identifier can be a source L2ID, which is determined by the second terminal device. The source L2 ID in the first broadcast message and the second broadcast message are the same.

[0251] Upon receiving the second broadcast message, the first terminal device resets the first timer. If the first timer expires and the first terminal device has not received the second broadcast message within the duration of the first timer, the first terminal device determines that it has not received the second broadcast message within the first duration.

[0252] It should be understood that if the first timer has already been started when the first terminal device receives the first broadcast message, starting the first timer can be understood as resetting the first timer.

[0253] For example, a first terminal device can receive discovery messages broadcast by multiple terminal devices and configure multiple timers for these terminal devices to monitor the discovery messages sent by the terminal devices during the runtime of the timers corresponding to the terminal devices. For instance, the first terminal device can receive a fourth broadcast message sent by a third terminal device, the fourth broadcast message including a second identifier used to identify the third terminal device. After receiving the fourth broadcast message, the first terminal device starts a second timer corresponding to the second identifier to detect a fifth broadcast message sent by the third terminal device during the runtime of the second timer. For example, the fourth broadcast message and the fifth broadcast message are discovery messages sent by the third terminal device at different times.

[0254] In this embodiment, the first terminal device can maintain a timer for each terminal device, which can effectively detect the broadcast messages of multiple terminal devices in order to determine whether the multiple terminal devices are suitable as relay devices for the first terminal device.

[0255] In one possible implementation, the first timer is controlled by the protocol layer of the first terminal device, the protocol layer including any one of the Radio Resource Control (RRC) layer, the physical layer, the Media Access Control (MAC) layer, and the discovery protocol layer.

[0256] For example, the first timer is controlled by the protocol layer of the first terminal device. For instance, the protocol layer can start or reset the first timer, or set its duration. This protocol layer includes any one of the Radio Resource Control (RRC) layer, the physical layer, the Media Access Control (MAC) layer, and the discovery protocol layer; that is, the first timer can be controlled by any one of these layers. For example, if the first timer is controlled by the RRC layer of the first terminal device, the physical layer of the first terminal device receives the first broadcast message, performs an L1 measurement, and submits the L1 measurement result to the RRC layer. After receiving the L1 measurement result from the physical layer, the RRC layer starts or resets the first timer. If the first timer is controlled by the physical layer or the MAC layer, after receiving the first broadcast message, the physical layer of the first terminal device or the physical layer instructs the MAC layer to start or reset the first timer. If the first timer expires, the physical layer or the MAC layer instructs the RRC layer not to receive a second broadcast message within the first duration after receiving the first broadcast message.

[0257] For example, after receiving the first broadcast message, the AS layer of the first terminal device can submit the relevant content of the first broadcast message to the discovery protocol layer. Therefore, the first timer can also be controlled by the discovery protocol layer. When the discovery protocol layer receives the relevant content of the first broadcast message, it starts or resets the first timer. If the discovery protocol layer detects that the first timer has expired, it instructs the RRC layer not to receive a second broadcast message within a first duration after receiving the first broadcast message.

[0258] For example, such as Figure 16 As shown, assuming that at time T0, the second terminal device meets the conditions for sending a discovery message and periodically broadcasts a discovery message to its surroundings. For example, the second terminal device periodically broadcasts a discovery message when the signal quality between it and the second network device meets a threshold condition. For example, the signal quality between the second terminal device and the second network device can be Uu-RSRP. At times T0, T1, T2, and T3, the second terminal device broadcasts a discovery message (such as...). Figure 16 (As indicated by the medium-thick arrow).

[0259] At times T0, T1, T2, and T3, the first terminal device receives and measures the discovery message broadcast by the second terminal device. For example, the physical layer of the first terminal device performs an L1 measurement on the discovery message, obtains the L1 measurement result, and submits the L1 measurement result to the RRC layer. After receiving the L1 measurement result, the RRC layer starts or resets the first timer. Alternatively, when the physical layer receives the discovery message, it sends an indication message to the RRC layer, indicating that the RRC layer has received the discovery message.

[0260] At time T4, the second terminal device no longer meets the conditions for sending the discovery message, and therefore stops sending the discovery message. At time T5, the first terminal device detects that the first timer has expired, but has not received the discovery message sent by the second terminal device. The first terminal device can determine that the second terminal device has stopped sending discovery messages, and therefore the first terminal device determines that the second terminal device is not a relay device for the first terminal device.

[0261] In one possible implementation, if the second terminal device is not a relay device for the first terminal device at the current moment... Figure 15A The communication method shown may also include step 1503.

[0262] 1503, the first terminal device deletes the measurement information corresponding to the second terminal device.

[0263] For example, the measurement information corresponding to the second terminal device may include the measurement identification information of the second terminal device. This measurement identification information is associated with the measurement reporting configuration of the second terminal device, and may also be associated with one or more of the serving cell information, the ID information of the second terminal device, and the signal quality of the sidelink of the second terminal device. After determining that the second terminal device is not a relay device for the first terminal device, the first terminal device deletes the measurement information corresponding to the second terminal device. That is, the measurement results reported by the first terminal device when subsequent measurement reporting is triggered do not include the measurement information of the second terminal device.

[0264] For example, the measurement information may include measurement entries recorded in the measurement variables of the first terminal device. The measurement entries recorded in the measurement variables may be the measurement ID information of the first terminal device, and the measurement variables may include measurement entries corresponding to multiple terminal devices. If the first terminal device determines that the second terminal device is not a relay device for the first terminal device, it deletes the measurement entry corresponding to the second terminal device from the measurement variables.

[0265] For example, the second terminal device periodically broadcasts a discovery message when the conditions for sending the discovery message are met. The first terminal device receives and measures the discovery message sent by the second terminal device to obtain the SD-RSRP corresponding to the second terminal device. When the SD-RSRP of the first terminal device meets the entry conditions for a measurement reporting event, the first terminal device treats the second terminal device as a measurement object and records the second terminal device in the measurement variables of the first terminal device, forming a measurement entry corresponding to the second terminal device. The first terminal device can also perform measurement reporting according to the measurement reporting configuration corresponding to the measurement reporting event.

[0266] For example, such as Figure 16As shown, assuming that at time T1, the first terminal device detects that the SD-RSRP of the second terminal device meets the entry condition for measurement reporting event Y, that is, during the first time period, the signal quality of the serving cell of the first terminal device remains below the threshold Y1, and the SD-RSRP of the second terminal device remains above the threshold Y2. The duration of this first time period is greater than or equal to the duration of TimeToTrigger. The first terminal device takes the second terminal device as the measurement object, records the second terminal device in the measurement variables of the first terminal device, and performs measurement reporting according to the measurement reporting configuration corresponding to measurement reporting event Y. At time T4, the second terminal device does not meet the sending condition of the discovery message, for example, the Uu-RSRP of the second terminal device does not meet the threshold condition, so the second terminal device stops sending the discovery message. At time T5, the first terminal device does not receive the discovery message sent by the second terminal device, so it is determined that the second terminal device has stopped sending the discovery message. The fact that the second terminal device stops sending the discovery message indicates that the second terminal device is no longer suitable for providing relay service, so the first terminal device can delete the second terminal device from the above measurement variables, that is, delete the measurement entry corresponding to the second terminal device.

[0267] It is understood that the aforementioned measurement reporting event Y is merely an example. The first terminal device may record the second terminal device as a measurement object in its measurement variables if the signal quality of the side link between it and the second terminal device meets the entry conditions for the measurement reporting event. This measurement reporting event can be the aforementioned measurement reporting event Y, or it can be other measurement reporting events. For example, the entry condition for this measurement reporting event is: the signal quality difference between the signal quality of the surrounding relay device on the side link and the signal quality of the serving cell is greater than a fourth threshold. This application does not limit the scope of this measurement reporting event.

[0268] Understandably, at time T5, if the first terminal device does not receive the discovery message sent by the second terminal device, the first terminal device can determine that the SD-RSRP of the second terminal device meets the exit condition in the measurement reporting event, or determine that the SD-RSRP of the second terminal device is 0, which meets the exit condition of the measurement reporting event Y. The first terminal device then deletes the second terminal device from the measurement variables, that is, deletes the measurement entry corresponding to the second terminal device.

[0269] For a detailed explanation of the measurement reporting event Y, please refer to the relevant description above, which will not be elaborated here.

[0270] In this embodiment of the application, after determining that the second terminal device is not a relay device of the first terminal device, the measurement information corresponding to the second terminal device is deleted from the measurement variables, ensuring that the measurement report includes the measurement results of the appropriate terminal device, while saving the memory space occupied by the measurement results and reducing the resources required to report the measurement results.

[0271] Please see Figure 15B , Figure 15B An interactive schematic diagram of another communication method provided in the embodiments of this application is shown below. Figure 15B As shown, the method includes:

[0272] 1501, the second terminal device sends a first broadcast message, and correspondingly, the first terminal device receives the first broadcast message.

[0273] 1502, if the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message, then it is determined that the second terminal device is not a relay device of the first terminal device.

[0274] The specific implementation methods of steps 1501 and 1502 can be found in [reference]. Figure 15A As shown, details will not be elaborated here.

[0275] In one possible implementation, a unicast connection exists between the first terminal device and the second terminal device. Before determining that the second terminal device is not a relay device for the first terminal device, the first terminal device may perform the following operations: The first terminal device sends a first indication message to the second terminal device through the unicast connection. The first indication message is used to trigger the second terminal device to send a first message. The first message is used to measure a first signal quality, which is the signal quality between the first terminal device and the second terminal device; the first terminal device receives the first message; the first terminal device determines the first signal quality based on the first message. The first terminal device determining that the second terminal device is not a relay device for the first terminal device can be done by: if the first signal quality is less than a first threshold, the first terminal device determines that the second terminal device is not a relay device for the first terminal device.

[0276] For example, the first message can be any message sent by the second terminal device to the first terminal device. For example, a unicast connection exists between the first and second terminal devices, and the second terminal device provides relay services to the first terminal device. In the absence of data transmission in the unicast connection between the first and second terminal devices, the first terminal device can measure the signal quality with the second terminal device based on a discovery message broadcast by the second terminal device. For example, if the first terminal device does not receive a second broadcast message from the second terminal device within a first duration after receiving the first broadcast message, it can determine that the second terminal device has stopped sending discovery messages. The first and second broadcast messages are discovery messages broadcast by the second terminal device at different times. After determining that the second terminal device has stopped sending discovery messages, the first terminal device can send a first indication message to the second terminal device. This first indication message triggers the second terminal device to send a first message, enabling the first terminal device to measure the first signal quality based on the first message. The first signal quality can be SL-RSRP. The first terminal device receives and measures the first message to obtain the first signal quality. If the first signal quality is less than a first threshold, the second terminal device is no longer suitable to provide relay services to the first terminal device. Therefore, the first terminal device determines that the second terminal device is not a relay device for the first terminal device. For example, the first threshold can be the threshold X1 in the measurement reporting event X.

[0277] Understandably, if the first signal quality is greater than or equal to the first threshold, it indicates that the signal quality of the side link between the first terminal device and the second terminal device meets the requirements of the second terminal device to provide relay services to the first terminal device, the second terminal device can continue to provide relay services to the first terminal device, and the first terminal device can continue to use the second terminal device as a relay device for the first terminal device.

[0278] In this embodiment, when the second terminal device provides a relay device for the first terminal device, if the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message, data transmission between the first and second terminal devices can be triggered by the first indication information to detect the first signal quality between the first and second terminal devices. When the first signal quality is less than a first threshold, it is determined that the second terminal device is not a relay device for the first terminal device; when the first signal quality is not less than the first threshold, it is determined that the second terminal device can continue to serve as a relay device for the first terminal device, thus avoiding unnecessary switching.

[0279] 1504, the first terminal device reports the measurement results to the first network device. Correspondingly, the first network device receives the measurement results.

[0280] For example, the first network device is the network device that connects the first terminal device to the network. The measurement results may include measurement results of the surrounding selectable cells and measurement results of the surrounding selectable relay terminals of the first terminal device. Understandably, the measurement results of the surrounding selectable cells or the surrounding selectable relay terminals of the first terminal device satisfy the entry conditions for the corresponding measurement reporting event. The measurement results of the surrounding selectable cells include the ID of the surrounding selectable cell and the signal quality of the surrounding selectable cell. The measurement results of the surrounding selectable relay terminals may include the ID of the surrounding selectable relay terminal, the ID of the serving cell of the surrounding selectable relay terminal, and the signal quality of the surrounding selectable relay terminal. When the first terminal device is in RRC connected state, after determining that the second terminal device is no longer suitable as a relay device for the first terminal device, the first terminal device can trigger measurement reporting and report the measurement results to the first network device. After receiving the measurement results, the first network device can instruct the first terminal device to switch from the second terminal device to one of the surrounding selectable cells or the surrounding selectable relay terminals based on the measurement results.

[0281] For example, a unicast connection exists between the first terminal device and the second terminal device, and the second terminal device provides relay services to the first terminal device. The first terminal device obtains relay services through the second terminal device, thereby accessing the first network device, and the first terminal device can report measurement results to the first network device through the second terminal device.

[0282] For example, when the first terminal device is in RRC connected state, the first terminal device detects the signal quality of the sidelink between itself and the second terminal device, the signal quality of surrounding cells, and the signal quality of surrounding relay terminals to perform measurement reporting. In the case where there is no data transmission between the first and second terminal devices, i.e., no unicast connection data transmission between them, the first terminal device can detect the signal quality of the sidelink between itself and the second terminal device based on the discovery message broadcast by the second terminal device; that is, the first terminal device measures the SD-RSRP of the second terminal device.

[0283] For example, if the conditions for sending a discovery message are met, the second terminal device can periodically broadcast discovery messages. If the first terminal device does not receive a second broadcast message from the second terminal device within a first duration after receiving the first broadcast message, the first terminal device determines that the second terminal device has stopped sending discovery messages. The first broadcast message and the second broadcast message are discovery messages sent by the second terminal device at different times. Upon determining that the second terminal device has stopped sending the discovery message, the first terminal device determines that the second terminal device is no longer suitable to provide relay services for the first terminal device. Therefore, the first terminal device can trigger measurement reporting and report the measurement results to the first network device. It is understood that the measurement results should meet the entry conditions of the corresponding measurement reporting event. After determining that the second terminal device will not be used as a relay device for the first terminal device, the first terminal device reports the measurement results to the first network device, so that the first network device can instruct the first terminal device's relay device to switch from the second terminal device to a nearby selectable cell or a nearby selectable relay terminal based on the measurement results.

[0284] For example, when the measurement variables include at least one measurement object, the first terminal device triggers a measurement report, and the reported measurement result includes the measurement result corresponding to the at least one measurement object. When there is no measurement object in the measurement variables, the first terminal device can detect the signal quality of surrounding cells and the signal quality of the sidelinks between them and surrounding relay terminals. For example, if the signal quality of a surrounding cell meets the measurement reporting conditions in its corresponding measurement reporting configuration, the surrounding cell is added to the measurement variables of the first terminal device, and the measurement result is reported, including the measurement result corresponding to the surrounding cell.

[0285] In one possible implementation, the first terminal device can determine, based on an instruction from the first network device, that the second terminal device is not a relay device for the first terminal device. For example, after determining that the second terminal device has stopped sending discovery messages, the first terminal device can trigger measurement reporting, reporting the measurement results to the first network device. The first network device determines, based on the measurement results, whether to continue using the second terminal device as a relay device for the first terminal device. If the first network device determines that it will no longer use the second terminal device as a relay device for the first terminal device, the first network device sends a fifth indication message to the first terminal device, indicating that the second terminal device will not be used as a relay device for the first terminal device. After receiving the fifth indication message, the first terminal device determines that the second terminal device is no longer suitable as a relay device for the first terminal device. For example, the first terminal device can also perform a handover from non-direct communication to direct communication, or a handover from non-direct communication to non-direct communication, based on the fifth indication message. That is, the first terminal device can switch from the second terminal device to a nearby selectable cell, or to a nearby selectable relay terminal, based on the fifth indication message.

[0286] For example, the first terminal device reporting the measurement result to the first network device may be as follows: When it is determined that the second terminal device has stopped sending discovery messages and the signal quality of nearby selectable cells meets the entry conditions for a measurement reporting event, the first terminal device reports the measurement result to the first network device. For instance, the first terminal device reports the measurement result to the first network device when it is determined that the second terminal device has stopped sending discovery messages and the signal quality of nearby selectable cells is greater than a threshold X1.

[0287] For example, such as Figure 16 As shown, assuming that before time T5, the first terminal device detects that the signal quality of the second terminal device's sidelink is greater than the threshold X1, the entry condition for measurement reporting event X is not met, and measurement reporting will not be triggered. At time T5, if the first terminal device does not receive a discovery message from the second terminal device, it is determined that the second terminal device stops sending discovery messages. At this time, if the first terminal device detects that the signal quality of nearby selectable cells is greater than the threshold X2, the measurement reporting corresponding to measurement reporting event X is triggered. For example, the first terminal device can record the second terminal device as the measurement object in the first terminal device's measurement variables and perform measurement reporting according to the measurement reporting configuration of measurement reporting event X.

[0288] Understandably, if the first terminal device determines that the second terminal device has stopped sending discovery messages, the first terminal device can determine that the SD-RSRP of the second terminal device is 0, or that the SD-RSRP of the second terminal device is less than the threshold X1, satisfying the condition in measurement reporting event X that the signal quality of the side link between the remote terminal and the serving relay terminal is less than the threshold X1. When the first terminal device detects that the signal quality of the surrounding selectable cells is greater than the threshold X2, the entry condition for measurement reporting event X is met, triggering the measurement reporting corresponding to measurement reporting event X.

[0289] For a detailed explanation of the measurement reporting event X, please refer to the relevant description above, which will not be elaborated here.

[0290] In this embodiment of the application, when the second terminal device is already a relay device for the first terminal device, after the first terminal device determines that the second terminal device is not a relay device for the first terminal device, it triggers measurement reporting and reports the measurement results to the first network device so that the first network device can instruct the first terminal device to switch to a suitable cell or relay device based on the measurement results.

[0291] Please see Figure 15C , Figure 15C This is an interactive schematic diagram illustrating another communication method provided in an embodiment of this application. For example... Figure 15C As shown, the method includes:

[0292] 1501, the second terminal device sends a first broadcast message, and correspondingly, the first terminal device receives the first broadcast message.

[0293] 1502, if the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message, then it is determined that the second terminal device is not a relay device of the first terminal device.

[0294] The specific implementation methods of steps 1501 and 1502 can be found in [reference]. Figure 15A As shown, details will not be elaborated here.

[0295] 1505, the first terminal device determines to reselect the relay device.

[0296] For example, when the first terminal device is in an RRC idle state or an RRC inactive state, after determining that the second terminal device is not a relay device for the first terminal device, the first terminal device determines to reselect a relay device. Figure 16As shown, assuming that before time T5, the first terminal device detects that the SD-RSRP of the second terminal device is greater than a preset threshold based on the discovery message sent by the second terminal device, and at time T5, the first terminal device does not receive the discovery message from the second terminal device, the first terminal device determines that the second terminal device has stopped sending discovery messages. Therefore, the second terminal device is no longer suitable as a relay device for the first terminal device, and the first terminal device can reselect a relay device.

[0297] It should be understood that if the first terminal device does not receive a discovery message from the second terminal device at time T5, the first terminal device can determine that the SD-RSRP of the second terminal device is 0, which satisfies the triggering condition for relay device reselection.

[0298] In this embodiment of the application, when the first terminal device is in an RRC idle state or an RRC inactive state, after determining that the second terminal device is not a relay device of the first terminal device, the first terminal device can trigger the first terminal device to reselect the relay device so that the first terminal device can switch to a suitable relay device.

[0299] Please see Figure 17 , Figure 17 This is an interactive schematic diagram illustrating another communication method provided in an embodiment of this application. For example... Figure 17 As shown, the communication method includes, but is not limited to, the following steps.

[0300] 1701, the second terminal device sends a first broadcast message, and correspondingly, the first terminal device receives the first broadcast message.

[0301] It is understood that the specific implementation of step 1701 can be found in [reference]. Figure 15A The relevant description of step 1501 will not be repeated here.

[0302] 1702, if no second broadcast message is received within a first time period after receiving the first broadcast message, the first terminal device deletes the measurement information corresponding to the second terminal device.

[0303] It is understood that the specific implementation of step 1702 can be found in [reference]. Figure 15A The relevant description of step 1503 will not be repeated here.

[0304] In this embodiment, if the first terminal device does not receive a second broadcast message within a first time period after receiving the first broadcast message, it deletes the measurement information corresponding to the second terminal device. That is, the first terminal device may not perform the operation in step 1502 to determine that the second terminal device is not a relay device for the first terminal device. For example, deleting the measurement information corresponding to the second terminal device can be done as follows: if there is no unicast connection between the first and second terminal devices, the first terminal device can delete the measurement information corresponding to the second terminal device from the measurement results. If the second broadcast message is not received within a first time period after receiving the first broadcast message, it can be determined that the second terminal device is not suitable as a relay device for the first terminal device. Therefore, the measurement information corresponding to the second terminal device can be deleted, preventing the measurement results reported by the first terminal device from including measurement information corresponding to an unsuitable terminal device, and ensuring that the measurement results include measurement information corresponding to a suitable terminal device.

[0305] In some implementations, when there is a unicast connection between the first terminal device and the second terminal device, and the first terminal device is in RRC connection state, step 1702 can be replaced by: if no second broadcast message is received within a first time period after receiving the first broadcast message, the first terminal device reports the measurement result to the first network device.

[0306] When a unicast connection exists between the first terminal device and the second terminal device, and the first terminal device is in RRC connection state, the first terminal device can trigger measurement reporting to report the measurement results to the first network device, so that the first network device can instruct the first terminal device to switch to a relay device based on the measurement results, so that the first terminal device can switch to a suitable cell or relay device.

[0307] In one possible implementation, a unicast connection exists between the first terminal device and the second terminal device. Before reporting the measurement result to the first network device, the method further includes: the first terminal device sending first indication information to the second terminal device through the unicast connection, the first indication information being used to trigger the second terminal device to send a first message, the first message being used to measure a first signal quality, the first signal quality being the signal quality between the first terminal device and the second terminal device; the first terminal device receiving the first message; and the first terminal device determining the first signal quality based on the first message.

[0308] In this embodiment, a unicast connection exists between the first terminal device and the second terminal device. If there is no data transmission in the unicast connection between the first terminal device and the second terminal device, and the first terminal device does not receive a second broadcast message within a first time period after receiving the first broadcast message, the first terminal device can trigger the second terminal device to send a first message through the first indication information, so that there is data transmission between the first terminal device and the second terminal device. This allows the first terminal device to detect the first signal quality between the first terminal device and the second terminal device based on the first message, and can accurately determine whether the second terminal is suitable to continue providing relay services to the first terminal device.

[0309] In one possible implementation, reporting the measurement result to the first network device includes: when the first signal quality is less than a first threshold, the first terminal device reports the measurement result to the first network device.

[0310] In this embodiment, when the first signal quality is less than a first threshold, the first terminal device determines that the second terminal device is no longer suitable to provide relay services for the first terminal device. The first terminal device can report this to the first network device so that the first terminal device can switch to a suitable relay device according to the instructions of the first network device. When the first signal quality is not less than the first threshold, the first terminal device determines that the second terminal device is suitable to continue providing relay services for the first terminal device, and therefore no relay device switching is required, thus avoiding unnecessary switching.

[0311] In some implementations, when there is a unicast connection between the first terminal device and the second terminal device, and the first terminal device is in an RRC idle state or an RRC inactive state, step 1702 can be replaced by: if no second broadcast message is received within a first time period after receiving the first broadcast message, the first terminal device determines to reselect the relay device.

[0312] When a unicast connection exists between the first terminal device and the second terminal device, and the first terminal device is in an RRC idle state or an RRC inactive state, the first terminal device can determine to reselect a relay device so that the relay device of the first terminal device is switched to a suitable relay device.

[0313] Please see Figure 18A , Figure 18A This is an interactive schematic diagram illustrating another communication method provided in an embodiment of this application. For example... Figure 18A As shown, the communication method includes, but is not limited to, the following steps.

[0314] 1801, the second terminal device sends a first broadcast message, and correspondingly, the first terminal device receives the first broadcast message.

[0315] The first broadcast message includes first cell information of the second terminal device. For example, the first cell information may include serving cell information of the second terminal device, which may include the identification information of the serving cell. For example, the identification information may be a physical cell identifier (PCI) or a cell identity. The first broadcast message may be a discovery message broadcast by the second terminal device, indicating that the second terminal device can provide relay services. The first terminal device receives the first broadcast message sent by the second terminal device and obtains the first cell information from the first broadcast message.

[0316] 1802, the first terminal device determines whether the serving cell of the second terminal device has been switched based on the first cell information.

[0317] For example, the first cell information includes the serving cell information of the second terminal device at a first moment, which is the moment when the second terminal device sends the first broadcast message, and can also be understood as the moment when the first terminal device receives the first broadcast message.

[0318] For example, the first terminal device can determine the serving cell information of the second terminal device before the first moment based on messages received from the second terminal device before the first moment. The first terminal device compares the serving cell information of the second terminal device at the first moment with the serving cell information before the first moment to determine whether the serving cell of the second terminal device has been switched.

[0319] For example, before receiving the first broadcast message, the first terminal device also receives a third broadcast message from the second terminal device. This third broadcast message includes third cell information of the second terminal device. The third cell information includes the identifier of the serving cell of the second terminal device at the time the third broadcast message was sent. The first terminal device can compare the third cell information with the first cell information and determine whether a handover has occurred based on the comparison result. If the first cell information and the third cell information are different, the first terminal device determines that a handover has occurred in the serving cell of the second terminal device. For example, if the identifier of the serving cell in the first cell information and the third cell information are different, the first terminal device determines that a handover has occurred in the serving cell of the second terminal device. If the first cell information and the third cell information are the same, the first terminal device determines that a handover has occurred in the serving cell of the second terminal device.

[0320] In one implementation, the third broadcast message can be a discovery message broadcast by the second terminal device. After receiving the third broadcast message, the first terminal device can also measure the signal quality between itself and the second terminal device based on the third broadcast message, i.e., measure the SD-RSRP of the second terminal device. If the SD-RSRP of the second terminal device satisfies the entry condition of the measurement reporting event Y, i.e., the SD-RSRP is greater than the threshold Y2, the first terminal device records the second terminal device as a measurement object in the measurement variables, forming a measurement entry corresponding to the second terminal device. This measurement entry may include information about the serving cell of the second terminal device at the time of sending the third broadcast message.

[0321] For example, after receiving the first broadcast message and obtaining the first cell information from the first broadcast message, the first terminal device can determine the serving cell information of the second terminal device before the first moment from the measurement information corresponding to the second terminal device. The first terminal device then compares the serving cell information in the first cell information with the serving cell information associated with the measurement entry to determine whether the serving cell of the second terminal device has been switched.

[0322] At 1803, the first terminal device sends a second message, and correspondingly, the first network device receives the second message.

[0323] When the serving cell of the second terminal device is switched, the first terminal device sends a second message to the first network device, the second message including the first cell information. For example, the second message can be used to indicate that the serving cell of the second terminal device has been switched. Upon determining that the serving cell of the second terminal device has been switched, the first terminal device sends the second message to the first network device. This second message includes the aforementioned first cell information. After receiving the second message, the first network device can update the serving cell information of the second terminal device based on the first cell information.

[0324] In one implementation, sending the second message to the first network device can be achieved by sending the second message to the first network device when the measurement variables of the first terminal device include a measurement entry corresponding to the second terminal device. This measurement entry records the measurement results of the second terminal device. The inclusion of a measurement entry corresponding to the second terminal device in the measurement variables of the first terminal device indicates that the first terminal device had already reported the measurement information corresponding to the second terminal device to the first network device before the first moment. This measurement information includes the serving cell information of the second terminal device before the first moment. Therefore, when the first terminal device determines that the serving cell of the second terminal device has been switched, it sends the second message to the first network device so that the first network device can update the serving cell information of the second terminal device in a timely manner.

[0325] Optionally, if the measurement variables of the first terminal device do not include the measurement entries corresponding to the second terminal device, the first terminal device may not send the second message.

[0326] In this embodiment, when the first terminal device determines that the serving cell of the second terminal device has been switched, it sends a second message to the first network device so that the first network device can update the information of the serving cell of the second terminal device in a timely manner, thereby avoiding the failure of the relay device of the first terminal device to switch to the second terminal device due to the first network device not updating the information of the serving cell of the second terminal device in a timely manner.

[0327] In one possible implementation, the second message may include the measurement results of the first terminal device, whereby the first cell information is included in the measurement information corresponding to the second terminal device. For example, when the first terminal device determines that the serving cell of the second terminal device has been switched, it may trigger a measurement report, reporting the measurement results to the first network device. This measurement result includes the measurement information corresponding to the second terminal device, such as the measurement results associated with the measurement entry corresponding to the second terminal device, which includes the first cell information. By triggering the measurement report, the first terminal device can send the serving cell information of the second terminal device after the switch to the first network device, enabling the first network device to update the serving cell information of the second terminal device in a timely manner.

[0328] In one possible implementation, before sending the second message to the first network device, the first terminal device may perform the following operation: the first terminal device determines, based on the first cell information, whether the current serving cell of the second terminal device is a non-forbidden access cell. The first terminal device sending the second message to the first network device may be: if the current serving cell of the second terminal device is a non-forbidden access cell, the first terminal device sends the second message to the first network device.

[0329] For example, the aforementioned non-forbidden access cell refers to a cell that the first terminal device can access, meaning that the cell is not prohibited from access. The first terminal device determines whether the second terminal device's current serving cell is a non-forbidden access cell based on the aforementioned first cell information. If the second terminal device's current serving cell is a non-forbidden access cell, it means that the second terminal device can still support the first terminal device's access. The first terminal device will then send a second message to the first network device to ensure that the first network device updates the second terminal device's serving cell information in a timely manner.

[0330] For example, the first terminal device can determine whether the current serving cell of the second terminal device belongs to the allow-list. If the current serving cell of the second terminal device belongs to the allow-list, the current serving cell of the second terminal device is determined to be an allow-list. The allow-list may be configured by the first network device, pre-configured by the first terminal device, or configured by the network where the first terminal device is located; this application does not limit this.

[0331] In this embodiment, before sending the second message to the first network device, the first terminal device first determines whether the serving cell of the second terminal device is a non-blocked access cell to determine whether the second terminal device can provide relay services to the first terminal device. If the serving cell of the second terminal device is a non-blocked access cell, the second terminal device can provide relay services to the first terminal device. Therefore, the first terminal device sends the second message to the first network device so that the first network device can update the serving cell information of the second terminal device in a timely manner. This ensures that the first network device can make reasonable decisions and avoids a situation where the second terminal device cannot provide relay services to the first terminal device, but the first network device determines to use the second terminal device as the relay device for the first terminal device.

[0332] Please see Figure 18B , Figure 18B This is an interactive schematic diagram illustrating another communication method provided in an embodiment of this application. For example... Figure 18B As shown, the communication method includes, but is not limited to, the following steps.

[0333] 1801, the second terminal device sends a first broadcast message, and correspondingly, the first terminal device receives the first broadcast message.

[0334] The first broadcast message includes the first cell information of the second terminal device.

[0335] 1804, the first terminal device determines whether the current serving cell of the second terminal device is a prohibited access cell based on the first cell information.

[0336] 1805, if the current serving cell of the second terminal device is a prohibited cell, the first terminal device deletes the measurement information corresponding to the second terminal device.

[0337] For example, the measurement information corresponding to the second terminal device includes the measurement entries corresponding to the second terminal. The prohibited access cell is determined by the first network device. If the current serving cell of the second terminal device is a prohibited access cell, it indicates that the second terminal device is not suitable as a relay device for the first terminal device. Therefore, the first terminal device can trigger the exit condition of the measurement reporting event corresponding to the second terminal device and delete the measurement entry corresponding to the second terminal device from the measurement variables. For example, if the measurement reporting event corresponding to the second terminal device has already triggered measurement reporting, the measurement reporting corresponding to the measurement reporting event is stopped.

[0338] For example, the first network device can configure a block list for the first terminal device. If the serving cell of the second terminal device is in the block list, then the serving cell of the second terminal device is determined to be a block cell, and the first terminal device deletes the measurement information corresponding to the second terminal device. Alternatively, the block list can also be based on the pre-configuration of the first terminal device or network configuration.

[0339] In this embodiment of the application, when the current serving cell of the second terminal device is a prohibited access cell, the second terminal device cannot provide relay services to the first terminal device. Therefore, the first terminal device can delete the measurement information corresponding to the second terminal device from the measurement results of the first terminal device. This can ensure that the reported measurement results include the appropriate measurement information of the terminal device, while saving the memory space occupied by the measurement results and reducing the resources required by the first terminal device when reporting the measurement results.

[0340] Please see Figure 19 , Figure 19 This is an interactive schematic diagram illustrating another communication method provided in an embodiment of this application. For example... Figure 19 As shown, the communication method includes, but is not limited to, the following steps.

[0341] 1901, the second terminal device sends a first broadcast message, and correspondingly, the first terminal device receives the first broadcast message, which includes the first cell information of the second terminal device.

[0342] For details on the implementation of step 1901, please refer to [link / reference]. Figure 18A The specific description of step 1801 shown will not be repeated here.

[0343] 1902, the first network device sends a third message, and correspondingly, the first terminal device receives the third message. The third message includes the second cell information of the second terminal device, and the third message is used to instruct the relay device of the first terminal device to switch to the second terminal device.

[0344] For example, the third message can be a handover command (such as a HO command message) sent by the first network device, and can be generated by the first network device based on the measurement results reported by the first terminal device. For example, the first terminal device can measure the signal quality with the second terminal device. When the signal quality with the second terminal device meets the entry conditions of the measurement reporting event corresponding to the second terminal device, the first terminal device triggers measurement reporting and reports the measurement results to the first network device. The measurement results can include measurement information corresponding to the second terminal device. For example, the measurement information can include the ID information of the serving cell of the second terminal device, the ID information of the second terminal device, and the signal quality with the second terminal device. After receiving the measurement results, the first network device determines, based on the measurement results, to use the second terminal device as a relay device for the first terminal device and sends a third message to the first terminal device. The third message is used to instruct the relay device of the first terminal device to hand over to the second terminal device. The third message includes the second cell information of the second terminal device, through which the first terminal device can access the serving cell of the second terminal device.

[0345] It is understood that the first terminal device may execute step 1901 first and then step 1902, or execute step 1902 and step 1902 simultaneously, or execute step 1902 first and then step 1901. This application does not impose any limitations.

[0346] 1903, if the information of the first cell is inconsistent with the information of the second cell, the first terminal device determines that the handover has failed.

[0347] For example, if the information of the first cell is inconsistent with the information of the second cell, it means that the second terminal device has already performed cell handover. Therefore, the first terminal device determines that the handover has failed and does not perform subsequent handover actions.

[0348] In one implementation, after the first terminal device determines that the handover has failed, the method further includes at least one of the following:

[0349] The first terminal device records a handover failure.

[0350] The first terminal device disconnects from the second terminal device;

[0351] The first terminal device performs Radio Resource Control (RRC) connection reconstruction.

[0352] For example, if the first terminal device determines that the handover has failed, it can perform handover failure processing, such as recording the handover failure, disconnecting the unicast connection with the second terminal device, and re-establishing the RRC connection. For example, the first terminal device can record a measurement of the handover failure and, upon receiving a request from the first network device, send the measurement record to the first network device.

[0353] In one implementation, if the information of the first cell and the information of the second cell are inconsistent, and the first terminal device receives a unicast connection establishment request message from the second terminal device, the first terminal device can reply with a unicast connection rejection message to the second terminal device. This unicast connection rejection message may include a rejection reason. The rejection reason may include any one of the following: security policy not aligned, protocol error, or unspecified. It should be understood that the above rejection reasons are merely examples, and the rejection reasons in this application embodiment may also include other reasons, such as new reasons defined according to the application scenario. Therefore, the rejection reasons shown above should not be construed as limiting the implementation of this application.

[0354] In this embodiment, when the first terminal device receives a handover command from the first network device and discovery information from the second terminal device, it compares whether the cell information of the second terminal device carried in the handover command is the same as the cell information of the second terminal device carried in the discovery information. If the first cell information and the second cell information are inconsistent, the first terminal device determines that the handover has failed, thus avoiding resource waste in subsequent handover operations.

[0355] Please see Figure 20 , Figure 20 This is an interactive schematic diagram illustrating another communication method provided in an embodiment of this application. For example... Figure 20 As shown, the communication method includes, but is not limited to, the following steps.

[0356] 2001, the second terminal device measures the second signal quality, which is the signal quality between the second terminal device and the second network device.

[0357] For example, the second network device is a network device that connects the second terminal device to the network, and the second terminal device can communicate with the second network device through the Uu port. The aforementioned second signal quality can be Uu-RSRP, that is, the signal quality of the second terminal device on the direct link of the Uu port. Generally, the signal quality of Uu is obtained by measuring the cell beam, such as the SSB beam.

[0358] For example, when there is data or reference signal transmission on the direct link between the second terminal device and the second network device, the second terminal device can measure the quality of the second signal based on the transmitted data or reference signal. When there is no data transmission or reference signal on the direct link between the second terminal device and the second network device, the second terminal device can measure the quality of the second signal based on a broadcast message sent by the second network device.

[0359] For example, the second terminal device can determine whether to provide relay service based on the second signal quality. When the second signal quality meets a threshold condition, the second terminal device can provide relay service. The second terminal device can periodically broadcast discovery messages indicating that it can provide relay service. For example, the discovery message may carry the source L2 ID of the second terminal device. In some implementations, the second terminal device can change the source L2 ID in the discovery message after a cell handover.

[0360] In 2002, the second terminal device sends a second instruction message, and correspondingly, the first terminal device receives the second instruction message.

[0361] When the second terminal device fails to meet a threshold condition in terms of second signal quality, it sends a second indication message. This second indication message indicates that the second terminal device will not provide relay service. For example, when the second signal quality fails to meet the threshold condition, the second terminal device determines that it will not provide relay service and sends the second indication message. Upon receiving the second indication message, the first terminal device determines that the second terminal device will not provide relay service, and therefore determines that the second terminal device is unsuitable as a relay device for the first terminal device. The second signal quality refers to the signal quality between the second terminal device and the second network device, which is the network device that connects the second terminal device to the network. For example, the second terminal device sends the second indication message when the second signal quality is greater than a second threshold or greater than a third threshold. The second and third thresholds can be configured by the second network device. For example, the second threshold is the minimum threshold for the signal quality of the second terminal device on the Uu port when it can send a discovery message, and the third threshold is the maximum threshold for the signal quality of the second terminal device on the Uu port when it can send a discovery message.

[0362] For example, such as Figure 16 As shown, assuming that at time T0, the second terminal device meets the conditions for sending a discovery message and periodically broadcasts a discovery message to its surroundings. For example, the second terminal device periodically broadcasts a discovery message when the signal quality between it and the second network device meets a threshold condition. For example, the signal quality between the second terminal device and the second network device can be Uu-RSRP. At times T0, T1, T2, and T3, the second terminal device broadcasts a discovery message (such as...). Figure 16 (As indicated by the thick arrow). At time T4, the second terminal device no longer meets the conditions for sending the discovery message, and the second terminal device can send the aforementioned second indication information (such as...). Figure 16 (As indicated by the thin arrow). At time T4, the first terminal device receives the second indication information sent by the second terminal device and can determine that the second terminal device does not provide relay service. Therefore, the first terminal device can determine at time T4 that the second terminal device is unsuitable as a relay device for the first terminal device, without waiting for the first timer to expire at time T5. In other words, the first terminal device can determine more quickly that the second terminal device is unsuitable as a relay device for the first terminal device based on the second indication information sent by the second terminal device.

[0363] For example, the second terminal device can broadcast the second indication information to inform surrounding terminal devices that it does not provide relay services. For instance, the second indication information can be included in a discovery message broadcast by the second terminal device, which carries the second indication information indicating that the second terminal device does not provide relay services. Alternatively, the second indication information can be a separate indication message broadcast by the second terminal device. Correspondingly, after receiving the second indication information, the first terminal device determines that the second terminal device is not a relay device for the first terminal device.

[0364] In some implementations, there is a unicast connection between the second terminal device and the first terminal device. In step 2002, sending the second indication information may be: the second terminal device sends the second indication information to the first terminal device based on the unicast connection.

[0365] For example, the second indication information may take the form of any one of PC5 signaling, PC5-RRC message, or sidelink media access control element (MAC CE).

[0366] In one implementation, a unicast connection exists between the first terminal device and the second terminal device, with the second terminal device providing relay services to the first terminal device. If the second signal quality is less than a second threshold or greater than a third threshold, the second terminal device is no longer suitable to provide relay services to the first terminal device. Therefore, the second terminal device can send a unicast connection release request to the first terminal device to release the unicast connection with it.

[0367] In this embodiment, if the second terminal device does not meet the threshold condition for the second signal quality, that is, if the second signal quality is less than the second threshold or less than the third threshold, the second terminal device does not provide relay service and sends the second indication information. This can promptly inform the surrounding terminal devices that the second terminal device does not provide relay service, thereby preventing the surrounding terminal devices from reporting the second terminal device as a relay device.

[0368] Please see Figure 21 , Figure 21 This is an interactive schematic diagram illustrating another communication method provided in an embodiment of this application. For example... Figure 21 As shown, the method may include the following steps.

[0369] 2101, the second terminal device sends a first broadcast message, and correspondingly, the first terminal device receives the first broadcast message.

[0370] Understandably, the specific implementation method of step 2101 can be found by referring to... Figure 15A The relevant description of step 1501 will not be detailed here.

[0371] In one possible implementation, the first broadcast message includes a first identifier for identifying the second terminal device, which is generated by the second terminal device when accessing its serving cell.

[0372] For example, the first identifier can be a source L2 ID, which is determined by the second terminal device. After receiving the first broadcast message, the first terminal device can determine that the first broadcast message comes from the second terminal device based on the first identifier carried in the first broadcast message. For example, the first terminal device can receive multiple broadcast messages from multiple terminal devices and determine the sender of the multiple broadcast messages based on the identifiers carried in the multiple broadcast messages. The first terminal device can determine that broadcast messages carrying different identifiers are broadcast messages from different terminal devices. For example, if the first terminal device receives a fourth broadcast message that carries a second identifier, and the second identifier is different from the first identifier, then it determines that the fourth broadcast message does not come from the second terminal device.

[0373] For example, the first broadcast message mentioned above is a discovery message broadcast by the second terminal device. The second terminal device can periodically send discovery messages, which include a source L2 ID. After a cell handover, the second terminal device can change the source L2 ID in the discovery message; that is, the source L2 ID carried in the discovery message currently sent by the second terminal device is the one generated when the second terminal device accesses the current serving cell. The first terminal device can receive discovery messages sent by multiple terminal devices and determine the sender of the discovery message based on the source L2 ID carried in the discovery message. Therefore, for a discovery message sent by the second terminal device after changing its source L2 ID, the first terminal device can consider that the discovery message does not originate from the second terminal device; that is, the first terminal device can treat the second terminal device after changing its source L2 ID as a new measurement object for measurement.

[0374] In this embodiment, the first terminal device can determine that the first broadcast message comes from the second terminal device based on the first identifier carried in the first broadcast message. After the second terminal device performs cell handover, the second terminal device is regarded as a new terminal device, that is, the second terminal device is used as a new measurement object for measurement. There is no need to update the serving cell information of the second terminal device, which can save the workload of the first terminal device and thus improve the measurement efficiency of the first terminal device.

[0375] In one possible implementation, the first broadcast message includes first cell information of the second terminal device, and after the first terminal device receives the first broadcast message sent by the second terminal device... Figure 21 The method shown may include steps 2102 and 2103.

[0376] 2102, the first terminal device determines whether the serving cell of the second terminal device has been switched based on the first cell information;

[0377] 2103, In the event of a handover of the serving cell of the second terminal device, the first terminal device sends a second message to the first network device, the second message including the information of the first cell.

[0378] For details on the implementation of steps 2102 and 2103, please refer to [link / reference]. Figure 18A The relevant descriptions of steps 1802 and 1803 are not detailed here.

[0379] In one possible implementation, Figure 21 The communication method shown may include steps 2104 and 2105.

[0380] 2104, The second terminal device measures the second signal quality, which is the signal quality between the second terminal device and the second network device.

[0381] 2105, the second terminal device sends the second instruction information, and correspondingly, the first terminal device receives the second instruction information.

[0382] If the second terminal device fails to meet the threshold condition for second signal quality, it sends a second indication message indicating that it will not provide relay service. Upon receiving the second indication message, the first terminal device determines that the second terminal device is not a relay device for the first terminal device.

[0383] It is understandable that the specific implementation methods of steps 2104 and 2105 above can be referred to Figure 20 The relevant descriptions of steps 2001 and 2002 are not detailed here.

[0384] 2106. If the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message, then it is determined that the second terminal device is not a relay device of the first terminal device.

[0385] Understandably, the specific implementation method for step 2106 can be found by referring to... Figure 15A The relevant description of step 1502 will not be detailed here.

[0386] It is understandable that the first terminal device may determine that the second terminal device is not a relay device of the first terminal device if it does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message, or if it receives a second indication message sent by the second terminal device.

[0387] For example, after determining that the second terminal device is not a relay device for the first terminal device, embodiments of this application also provide the following implementation methods:

[0388] Implementation Method 1: If the second terminal device is not a relay device for the first terminal device at the current moment, the first terminal device deletes the measurement information corresponding to the second terminal device.

[0389] Understandably, for details regarding the implementation of this first method, please refer to [link / reference]. Figure 15A The relevant description of step 1503 will not be detailed here.

[0390] Implementation Method 2: When the second terminal device is a relay device for the first terminal device at the current time, and the first terminal device is in RRC connection state, the first terminal device reports the measurement results to the first network device.

[0391] Understandably, for details regarding the implementation of this second method, please refer to [link / reference]. Figure 15B The relevant description of step 1504 will not be detailed here.

[0392] Implementation Method 3: When the second terminal device is the relay device of the first terminal device at the current time, and the first terminal device is in the RRC idle state or RRC inactive state, the first terminal device determines to reselect the relay device.

[0393] Understandably, for details regarding the implementation of this third method, please refer to [link / reference]. Figure 15C The relevant description of step 1505 will not be detailed here.

[0394] In one possible implementation, the first broadcast message includes the first cell information of the second terminal device; after the first terminal device receives the first broadcast message sent by the second terminal device, Figure 21 The communication method shown may include steps 2107 and 2108.

[0395] 2107, the first terminal device receives a third message from the first network device, the third message including the second cell information of the second terminal device, the third message being used to instruct the relay device of the first terminal device to switch to the second terminal device;

[0396] 2108, if the information of the first cell is inconsistent with the information of the second cell, the first terminal device determines that the handover has failed.

[0397] It is understandable that the specific implementation methods of steps 2107 and 2108 above can be referred to Figure 19 The relevant descriptions of steps 1902 and 1903 are not detailed here.

[0398] Understandably, if the first terminal device receives the third message before step 2106, it will compare the first cell information with the second cell information. If the first cell information and the second cell information are inconsistent, the first terminal device determines that the handover has failed and does not perform subsequent handover actions. If the first cell information and the second cell information are consistent, the first terminal device continues to perform subsequent actions. After the first terminal device determines that the handover has failed, it may record the handover failure, disconnect the unicast connection with the second terminal device, and perform one or more of the following: RRC connection reconstruction. If the first terminal device receives the third message after step 2106, it determines that the handover has failed without needing to compare the first cell information and the second cell information again.

[0399] In this embodiment, when the first terminal device receives a handover command from the first network device and discovery information from the second terminal device, it compares whether the cell information of the second terminal device carried in the handover command is the same as the cell information of the second terminal device carried in the discovery information. If the first cell information and the second cell information are inconsistent, the first terminal device determines that the handover has failed and does not perform subsequent handover operations, thus avoiding resource waste in subsequent handover operations.

[0400] In some implementations, the first terminal device can communicate with the network device using multiple serving relay terminals. The first terminal device can measure the measurement results of the serving relay terminal and surrounding relay terminals based on discovery messages sent by the serving relay terminal and surrounding relay terminals. The first terminal device can release or add relay terminals based on the measurement results of the serving relay terminal or surrounding relay terminals. For example, in a multi-path relaying communication scenario, the first terminal device can communicate with the network device through a serving relay terminal and a direct Uu port link. If the first terminal device detects that the signal quality of the serving relay terminal's side link is less than a preset threshold, or if the first terminal device cannot receive the discovery message sent by the serving relay terminal, it can report the measurement results to the first network device. The first network device can then instruct the first terminal device to release, add, or switch serving relay terminals based on these results. The signal quality of the serving relay terminal's side link can be SD-RSRP or SL-RSRP. For example, after detecting that a nearby relay terminal has stopped sending discovery messages, the first terminal device deletes the measurement information corresponding to that nearby relay terminal. For instance, the first terminal device can delete the measurement entry corresponding to that nearby relay terminal from its own measurement variables.

[0401] In this embodiment, for a serving relay terminal, after failing to receive a discovery message from that serving relay terminal, the first terminal device triggers a measurement report. For a nearby relay terminal, after failing to receive a discovery message from that nearby relay terminal, the first terminal device can delete the measurement information corresponding to that nearby relay terminal from the measurement results, ensuring that the first terminal device's measurement results include appropriate measurement information for nearby relay terminals. This allows the first terminal device to effectively release or add serving relay terminals.

[0402] In this embodiment, if the first terminal device does not receive a second broadcast message within a first time period after receiving the first broadcast message, it can determine that the second terminal device is not a relay device for the first terminal device, thereby more accurately determining whether the second terminal device is suitable as a relay device for the first terminal device. Optionally, the first terminal device can also determine that the second terminal device is not a relay device for the first terminal device upon receiving second indication information sent by the second terminal device. The first terminal device can determine whether the second terminal device is suitable as a relay device for the first terminal device more quickly based on the second indication information. Optionally, the first terminal device can also determine whether the serving cell of the second terminal device has been switched based on the first broadcast message. If the serving cell of the second terminal device has been switched, the first terminal device sends a second message to the first network device to update the serving cell information of the second terminal device in the first network device in a timely manner.

[0403] The following describes the communication device provided in the embodiments of this application.

[0404] This application divides the communication device into functional modules according to the above-described method embodiments. For example, each function can be divided into its own functional modules, or two or more functions can be integrated into one processing module. The integrated modules can be implemented in hardware or as software functional modules. It should be noted that the module division in this application is illustrative and represents only one logical functional division; other division methods may be used in actual implementation. The following will combine... Figures 22 to 24 The communication device of the embodiments of this application is described in detail.

[0405] Figure 22 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application, such as... Figure 22 As shown, the communication device includes a processing unit 2201 and a transceiver unit 2202.

[0406] In some embodiments of this application, the communication device may be the first terminal device shown above. That is... Figure 22 The communication device shown can be used to perform the steps or functions performed by the first terminal device in the above method embodiments.

[0407] Transceiver unit 2202 is used to receive a first broadcast message sent by the second terminal device;

[0408] Processing unit 2201 is configured to determine that the second terminal device is not a relay device of the first terminal device if the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message.

[0409] Optionally, the processing unit 2201 is also configured to delete the measurement information corresponding to the second terminal device.

[0410] Optionally, processing unit 2201 is also configured to determine the reselection of relay devices. For example, processing unit 2201 is also configured to report measurement results to the first network device.

[0411] Optionally, the transceiver unit 2202 is further configured to send first indication information to the second terminal device and receive the first message. The processing unit 2201 is further configured to determine a first signal quality based on the first message, and if the first signal quality is less than a first threshold, determine that the second terminal device is not a relay device for the first terminal device.

[0412] Optionally, the transceiver unit 2202 is also configured to receive second indication information from the second terminal device.

[0413] Optionally, the processing unit 2201 is further configured to determine whether a handover has occurred in the serving cell of the second terminal device. The transceiver unit 2202 is further configured to send a second message to the first network device.

[0414] Optionally, the processing unit 2201 is further configured to determine whether the current serving cell of the second terminal device is a non-forbidden access cell; the transceiver unit is specifically configured to send the second message to the first network device when the current serving cell of the second terminal device is a non-forbidden access cell.

[0415] Optionally, the processing unit 2201 is further configured to delete the measurement information corresponding to the second terminal device when the current serving cell of the second terminal device is a prohibited access cell.

[0416] Optionally, the transceiver unit 2202 is further configured to receive a third message from the first network device; the processing unit 2201 is further configured to determine that the handover has failed when the first cell information and the second cell information are inconsistent.

[0417] Optionally, the processing unit 2201 is also used to record handover failures, disconnect from the second terminal device, or perform Radio Resource Control (RRC) connection reconstruction.

[0418] Optionally, the transceiver unit 2202 is also used to receive third indication information from the first network device.

[0419] Optionally, the processing unit 2201 is also used to start the first timer; or, for example, the processing unit 2201 is also used to reset the first timer.

[0420] It is understood that specific descriptions of the first broadcast message, second broadcast message, measurement information, first indication information, first message, first signal quality, second indication information, second message, or third message can be found in the method embodiments shown above, such as... Figure 15A , Figure 15B , Figure 15C , Figure 17 , Figure 18A , Figure 18B , Figure 19 , Figure 20 , Figure 21 The methods shown will not be described in detail here.

[0421] It is understood that the specific descriptions of the transceiver unit and processing unit shown in the embodiments of this application are merely examples. For the specific functions or execution steps of the transceiver unit and processing unit, please refer to the above method embodiments, which will not be detailed here. For example, the transceiver unit 2202 can also be used for the receiving steps in steps 1501, 1701, 1801, 1901, 1902, 2002, 2101, and 2105, and the sending steps in steps 1504, 1803, and 2103; the processing unit 2201 can also be used to execute steps 1502, 1503, 1505, 1702, 1802, 1804, 1805, 1903, 2102, 2104, and 2106.

[0422] Reuse Figure 22 In other embodiments of this application, the communication device may be the second terminal device shown above. That is... Figure 22 The communication device shown can be used to perform the steps or functions performed by the second terminal device in the above method embodiments.

[0423] Processing unit 2201 is used to measure the quality of the second signal;

[0424] The transceiver unit 2202 is used to send the second instruction information.

[0425] It is understood that specific details regarding the second signal quality or second indication information can be found in the method embodiments shown above, such as... Figure 15A , Figure 15B , Figure 15C , Figure 17 , Figure 18A , Figure 18B , Figure 19 , Figure 20 The methods shown will not be described in detail here.

[0426] It is understood that the specific descriptions of the transceiver unit and processing unit shown in the embodiments of this application are merely examples. For the specific functions or execution steps of the transceiver unit and processing unit, please refer to the above method embodiments, which will not be described in detail here. For example, the transceiver unit 2202 is also used to perform the sending steps of steps 1501, 1701, 1801, 1901, 2002, and 2101; the processing unit is also used to perform step 2001.

[0427] The first terminal device and the second terminal device according to embodiments of this application have been described above. The following describes the possible product forms of the first terminal device and the second terminal device. It should be understood that any device possessing the above-described features... Figure 22 Any product of any form that possesses the functions of the first terminal device, or any product that has the above-mentioned features. Figure 22 Any form of the second terminal device that performs the functions described herein falls within the protection scope of the embodiments of this application. It should also be understood that the following description is merely illustrative and does not limit the product forms of the first and second terminal devices in the embodiments of this application to these examples.

[0428] Figure 22 In the communication device shown, the processing unit 2201 may be one or more processors, and the transceiver unit 2202 may be a transceiver. Alternatively, the processing unit 2201 may be one or more processors (or the processing unit 2201 may be one or more logic circuits), and the transceiver unit 2202 may be an input / output interface. This will be described in detail below.

[0429] In one possible implementation, Figure 22 In the communication device shown, the processing unit 2201 may be one or more processors, and the transceiver unit 2202 may be a transceiver. In the embodiments of this application, the processor and the transceiver may be coupled, etc., and the connection method between the processor and the transceiver is not limited in the embodiments of this application.

[0430] like Figure 23 As shown, the communication device 230 includes one or more processors 2320 and transceivers 2310.

[0431] For example, when the communication device is used to perform the steps, methods, or functions performed by the first terminal device, the transceiver 2310 is used to receive the first broadcast message sent by the second terminal device; the processor 2320 is used to determine that the second terminal device is not a relay device of the first terminal device.

[0432] For example, when the communication device is used to perform the steps, methods, or functions performed by the second terminal device described above, the processor 2320 is used to measure the second information quality; and the transceiver 2310 is used to send the second instruction information.

[0433] It is understood that specific descriptions of the first broadcast message, the second broadcast message, the second signal quality, or the second indication information, etc., can be found in the method embodiments shown above, such as... Figure 15A , Figure 15B , Figure 15C , Figure 17 , Figure 18A , Figure 18B , Figure 19 , Figure 20 The methods shown will not be described in detail here.

[0434] Understandably, for more detailed information on the processor and transceiver, please refer to [link / reference needed]. Figure 22 The descriptions of the processing unit and transceiver unit shown will not be repeated here.

[0435] exist Figure 23 In various implementations of the communication apparatus shown, the transceiver may include a receiver for performing a receiving function (or operation) and a transmitter for performing a transmitting function (or operation). The transceiver is also used to communicate with other devices / appliances via a transmission medium.

[0436] Optionally, the communication device 230 may further include one or more memories 2330 for storing program instructions and / or data. The memories 2330 and the processor 2320 are coupled. The coupling in this embodiment is an indirect coupling or communication connection between devices, units, or modules, and can be electrical, mechanical, or other forms, used for information exchange between devices, units, or modules. The processor 2320 may operate in conjunction with the memories 2330. The processor 2320 may execute program instructions stored in the memories 2330. Optionally, at least one of the aforementioned memories may be included in the processor.

[0437] This application embodiment does not limit the specific connection medium between the transceiver 2310, processor 2320, and memory 2330. This application embodiment... Figure 23 The memory 2330, processor 2320, and transceiver 2310 are connected via a bus 2340. Figure 23 The connections between other components are shown in bold and are for illustrative purposes only, not as limiting information. The bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, Figure 23 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0438] In the embodiments of this application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., and can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly manifested as being executed by a hardware processor, or being executed by a combination of hardware and software modules within the processor.

[0439] In this application embodiment, the memory may include, but is not limited to, non-volatile memory such as hard disk drive (HDD) or solid-state drive (SSD), random access memory (RAM), erasable programmable read-only memory (EPROM), read-only memory (ROM), or compact disc read-only memory (CD-ROM), etc. Memory is any storage medium capable of carrying or storing program code in the form of instructions or data structures, and capable of being read and / or written by a computer (such as the communication device shown in this application), but is not limited to this. The memory in this application embodiment may also be a circuit or any other device capable of implementing storage functions, used to store program instructions and / or data.

[0440] The processor 2320 is primarily used for processing communication protocols and data, controlling the entire communication device, executing software programs, and processing software program data. The memory 2330 is primarily used for storing software programs and data. The transceiver 2310 may include control circuitry and an antenna. The control circuitry is primarily used for converting baseband signals to radio frequency signals and processing radio frequency signals. The antenna is primarily used for transmitting and receiving radio frequency signals in the form of electromagnetic waves. Input / output devices, such as touchscreens, displays, and keyboards, are primarily used for receiving user input data and outputting data to the user.

[0441] When the communication device is powered on, the processor 2320 can read the software program in the memory 2330, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be transmitted wirelessly, the processor 2320 performs baseband processing on the data to be transmitted and outputs the baseband signal to the radio frequency (RF) circuit. The RF circuit processes the baseband signal and transmits the RF signal outward in the form of electromagnetic waves through the antenna. When data is sent to the communication device, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor 2320. The processor 2320 converts the baseband signal into data and processes the data.

[0442] In another implementation, the radio frequency circuitry and antenna can be set up independently of the processor performing baseband processing. For example, in a distributed scenario, the radio frequency circuitry and antenna can be arranged remotely, independent of the communication device.

[0443] It is understood that the communication device shown in the embodiments of this application may also have more than Figure 23 This application does not limit the use of other components or other related elements. The methods performed by the processor and transceiver shown above are merely examples; the specific steps performed by the processor and transceiver can be found in the methods described above.

[0444] In another possible implementation Figure 22 In the communication device shown, the processing unit 2201 can be one or more logic circuits, and the transceiver unit 2202 can be an input / output interface. This input / output interface may also be called a communication interface, an interface circuit, or an interface, etc. Figure 24 As shown, Figure 24 The communication device shown includes logic circuitry 2401 and interface 2402. That is, the processing unit 2201 can be implemented using logic circuitry 2401, and the transceiver unit 2202 can be implemented using interface 2402. The logic circuitry 2401 can be a chip, processing circuit, integrated circuit, or system-on-chip (SoC) chip, etc., and the interface 2402 can be a communication interface, input / output interface, pins, etc. For example, Figure 24 Taking the aforementioned communication device as an example, the chip includes logic circuit 2401 and interface 2402.

[0445] In this embodiment, the logic circuit and the interface can also be coupled to each other. The specific connection method between the logic circuit and the interface is not limited in this embodiment.

[0446] For example, when the communication device is used to perform the method, function or step performed by the first terminal device, the interface 2402 is used to receive a first broadcast message; the logic circuit 2401 is used to determine that the second terminal device is not a relay device of the first terminal device if the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message.

[0447] For example, when the communication device is used to perform the method, function or step performed by the second terminal device described above, interface 2402 is used to send second instruction information and send a first broadcast message.

[0448] It is understood that the communication device shown in the embodiments of this application can implement the method provided in the embodiments of this application in hardware form or in software form, etc., and the embodiments of this application do not limit it in this way.

[0449] It is understood that specific descriptions of the first broadcast message, the second broadcast message, the second signal quality, or the second indication information, etc., can be found in the method embodiments shown above, such as... Figure 15A , Figure 15B , Figure 15C , Figure 17 , Figure 18A , Figure 18B , Figure 19 , Figure 20 The methods shown will not be described in detail here.

[0450] for Figure 24 For specific implementations of the various embodiments shown, please refer to the above embodiments, which will not be described in detail here.

[0451] This application also provides a wireless communication system, which includes a first terminal device and a second terminal device. The first terminal device and the second terminal device can be used to execute the methods in any of the foregoing embodiments (such as...). Figure 15A , Figure 15B , Figure 15C , Figure 17 , Figure 18A , Figure 18B , Figure 19 , Figure 20 wait).

[0452] In addition, this application also provides a computer program for implementing the operations and / or processes performed by the first terminal device in the method provided in this application.

[0453] This application also provides a computer program for implementing the operations and / or processes performed by a second terminal device in the method provided in this application.

[0454] This application also provides a computer-readable storage medium storing computer code that, when executed on a computer, causes the computer to perform the operations and / or processes performed by the first terminal device in the method provided in this application.

[0455] This application also provides a computer-readable storage medium storing computer code that, when executed on a computer, causes the computer to perform the operations and / or processes performed by the second terminal device in the method provided in this application.

[0456] This application also provides a computer program product, which includes computer code or a computer program that, when run on a computer, causes the operations and / or processes performed by a first terminal device in the method provided in this application to be executed.

[0457] This application also provides a computer program product, which includes computer code or a computer program that, when run on a computer, causes the operations and / or processes performed by a second terminal device in the method provided in this application to be executed.

[0458] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices, or units, or it may be an electrical, mechanical, or other form of connection.

[0459] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the technical effects of the solutions provided in the embodiments of this application.

[0460] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0461] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned readable storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0462] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method, characterized in that, Applied to a first terminal device, which accesses a network through a first network device, including: The first terminal device receives a first broadcast message sent by the second terminal device. The first broadcast message includes the first cell information of the second terminal device. The first cell information includes the identifier information of the first cell. The first cell is the current serving cell of the second terminal device. The first terminal device determines, based on the first cell information, whether the serving cell of the second terminal device has been switched, and whether it is a non-prohibited access cell; If the serving cell of the second terminal device is switched over and the first cell is a non-blocked cell, the first terminal device sends a second message to the first network device. The second message includes the information of the first cell, so that the first network device updates the information of the serving cell of the second terminal device.

2. A communication method, characterized in that, Applied to a first terminal device, which accesses a network through a first network device, including: The first terminal device receives a first broadcast message sent by the second terminal device. The first broadcast message includes the first cell information of the second terminal device. The first cell information includes the identifier information of the first cell. The first cell is the current serving cell of the second terminal device. The first terminal device determines, based on the first cell information, whether the serving cell of the second terminal device has been switched, and whether it is a non-prohibited access cell; If a handover occurs in the serving cell of the second terminal device but the first cell is a prohibited access cell, the first terminal device deletes the measurement information corresponding to the second terminal device and does not send the measurement information corresponding to the second terminal device to the first network device.

3. The method according to claim 1 or 2, characterized in that, The information of the first cell is included in the measurement information corresponding to the second terminal device.

4. The method according to claim 1 or 2, characterized in that, After the first terminal device receives the first broadcast message sent by the second terminal device, the method further includes: The first terminal device receives a third message from the first network device, the third message including the second cell information of the second terminal device, the third message being used to instruct the relay device of the first terminal device to switch to the second terminal device; If the information of the first cell is inconsistent with the information of the second cell, the first terminal device determines that the handover has failed.

5. The method according to claim 4, characterized in that, After the first terminal device determines that the handover has failed, the method further includes at least one of the following: The first terminal device records a handover failure. The first terminal device disconnects from the second terminal device; The first terminal device performs Radio Resource Control (RRC) connection reconstruction.

6. The method according to claim 1 or 2, characterized in that, After the first terminal device receives the first broadcast message sent by the second terminal device, the method further includes: If the first terminal device does not receive a second broadcast message from the second terminal device within a first time period after receiving the first broadcast message. The first terminal device deletes the measurement information corresponding to the second terminal device and does not send the measurement information corresponding to the second terminal device to the first network device.

7. The method according to claim 6, characterized in that, The method further includes: The first terminal device receives third indication information from the first network device, the third indication information being used to indicate the first duration.

8. A communication device, characterized in that, include: The transceiver unit is used to receive a first broadcast message sent by the second terminal device. The first broadcast message includes first cell information of the second terminal device. The first cell information includes the identifier information of the first cell. The first cell is the current serving cell of the second terminal device. The processing unit is configured to determine, based on the first cell information, whether the serving cell of the second terminal device has been switched, and whether it is a non-prohibited access cell; The transceiver unit is further configured to send a second message to the first network device when the serving cell of the second terminal device has been switched and the first cell is a non-blocked access cell, the second message including the first cell information, so that the first network device updates the serving cell information of the second terminal device.

9. A communication device, characterized in that, include: The transceiver unit is used to receive a first broadcast message sent by the second terminal device. The first broadcast message includes first cell information of the second terminal device. The first cell information includes the identifier information of the first cell. The first cell is the current serving cell of the second terminal device. The processing unit is configured to determine, based on the first cell information, whether the serving cell of the second terminal device has been switched, and whether it is a non-prohibited access cell; The transceiver unit is further configured to delete the measurement information corresponding to the second terminal device and not send the measurement information corresponding to the second terminal device to the first network device when the serving cell of the second terminal device has been switched but the first cell is a prohibited access cell.

10. The apparatus according to claim 8 or 9, characterized in that, The information of the first cell is included in the measurement information corresponding to the second terminal device.

11. The apparatus according to claim 8 or 9, characterized in that, The transceiver unit is further configured to receive a third message from the first network device, the third message including second cell information of the second terminal device, and the third message being configured to instruct the relay device of the communication device to switch to the second terminal device; The processing unit is further configured to determine a handover failure if the information of the first cell is inconsistent with the information of the second cell.

12. The apparatus according to claim 11, characterized in that, The processing unit is further configured to perform at least one of the following: record a handover failure; disconnect from the second terminal device; or perform Radio Resource Control (RRC) connection reconstruction.

13. The apparatus according to claim 8 or 9, characterized in that, The processing unit is further configured to delete the measurement information corresponding to the second terminal device and not send the measurement information corresponding to the second terminal device to the first network device if no second broadcast message is received from the second terminal device within a first time period after receiving the first broadcast message.

14. The apparatus according to claim 13, characterized in that, The transceiver unit is further configured to receive third indication information from the first network device, the third indication information being used to indicate the first duration.

15. A communication device, characterized in that, Includes a communication unit and a processing unit: The communication unit is used to input and / or output signaling or data; The processing unit is configured to execute the method described in any one of claims 1-7 via the communication unit.

16. A communication device, characterized in that, Including processor and memory; The processor is used to store computer execution instructions; The processor is configured to execute the computer execution instructions to cause the method described in any one of claims 1-7 to be performed.

17. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program, which, when executed, performs the method according to any one of claims 1-7.

18. A chip system, characterized in that, Including communication interfaces and processors: The communication interface is used for inputting and / or outputting signaling or data; The processor is configured to execute a computer-executable program, causing a device having the chip system installed to perform the method as described in any one of claims 1-7.

19. A computer program product, characterized in that, The computer program product includes a computer program that, when executed, performs the method according to any one of claims 1-7.

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