Communication method, communication apparatus, and communication system

Abstract

The present application provides a communication method, a communication apparatus, and a communication system. The communication method is applied to a first terminal device, and the first terminal device communicates with an access network device via a second terminal device. The communication method comprises: receiving a first message from the second terminal device, wherein the first message is used for indicating that a radio link failure occurs between the second terminal device and the access network device; and stopping sending data to the second terminal device, wherein the data comprises data sent by the first terminal device to the access network device via the second terminal device. In this way, during reconnection between the first terminal device and the access network device, the first terminal device cleans cached uplink data. Even though the first terminal device has been reconnected to the access network device, the access network device will not receive a data packet that is forwarded by the second terminal device and encrypted by means of a key before reconnection, so that no bad data is obtained by decryption.

Description

Communication method, communication device and communication system

[0001] This application claims priority to the Chinese patent application with application number 202311276976.7 filed with the State Intellectual Property Office of China on September 28, 2023, and priority to the Chinese patent application with the invention name “Communication Method, Communication Device and Communication System”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communication technology, and more specifically, to a communication method, a communication device, and a communication system. Background Art

[0003] User equipment (UE) to network relay (U2N Relay) technology uses a relay terminal device (relay UE) to facilitate communication between a remote terminal device (remote UE) and access network equipment. The relay terminal device and the remote terminal device communicate via a sidelink (SL), while the relay terminal device and the access network equipment communicate over the air interface.

[0004] In existing solutions, after a relay terminal device detects a wireless link failure between it and an access network device, the remote terminal device and relay terminal device must reestablish connections with the access network device. During this reestablishment process, the access network device updates the encryption key used to encrypt data packets. However, after the remote terminal device and relay terminal device reestablish connections with the access network device, the access network device often decrypts incorrect data using the reestablished key.

[0005] Summary of the Invention

[0006] The present application provides a communication method, a communication device and a communication system. Through this communication method, after the first terminal device and the access network device are reestablished, the access network device will not receive the data packet encrypted by the original key, and thus no erroneous data will be decrypted.

[0007] In a first aspect, a communication method is provided. This communication method can be executed by a first terminal device, or alternatively, by a chip or circuit for the first terminal device, although this application does not limit this. For ease of description, the following description uses execution by the first terminal device as an example. The first terminal device communicates with an access network device via a second terminal device.

[0008] The communication method includes: receiving a first message from a second terminal device, the first message being used to indicate a wireless link failure between the second terminal device and the access network device; and stopping sending data to the second terminal device, the data including data sent by the first terminal device to the access network device via the second terminal device.

[0009] In the technical solution provided in this application, when a wireless link failure occurs between a second terminal device and an access network device, the second terminal device sends a first message to the first terminal device. Upon receiving the first message, the first terminal device stops sending uplink data to the second terminal device. Thus, during the reestablishment process between the first terminal device and the access network device, the first terminal device clears cached uplink data. Furthermore, after the reestablishment of the connection between the first terminal device and the access network device, the access network device will not receive data packets forwarded by the second terminal device that were encrypted using the pre-reestablishment key, thus preventing the access network device from decrypting erroneous data.

[0010] In a possible implementation, after stopping sending data to the second terminal device, the method further includes: sending a first request message to the second terminal device, where the first request message is used to request re-establishment of the connection between the first terminal device and the access network device.

[0011] Before the first terminal device requests reestablishment from the access network device through the second terminal device, the first terminal device stops sending data to the second terminal device. Thus, while the first terminal device and the access network device are reestablishing, the second terminal device will not receive data packets encrypted by the first terminal device using the pre-reestablishment key. Furthermore, after the first terminal device and the access network device are reestablished, the access network device will not receive data packets forwarded by the second terminal device that were encrypted using the pre-reestablishment key, preventing the access network device from decrypting incorrect data.

[0012] In one possible implementation, the first entity is released when a first condition is met. The first entity is used by a first terminal device to send a message to a second terminal device. The first condition includes the first terminal device receiving a first message or the first terminal device sending a first request message.

[0013] When the first terminal device receives the first message or sends the first request message, the first terminal device releases the first entity. This clears the first terminal device's cached data packets encrypted with the pre-reestablishment key. Consequently, after the first terminal device reestablishes its connection with the access network device, the access network device will not receive data packets forwarded by the second terminal device that were encrypted with the pre-reestablishment key, and thus the access network device will not decrypt erroneous data.

[0014] In one possible implementation, the first configuration is released when a second condition is met. The first configuration is used for the first terminal device to receive a message from the second terminal device. The second condition includes the first terminal device receiving the first message or the first terminal device sending a first request message.

[0015] When the first terminal device receives the first message or sends the first request message, it releases the first configuration. This way, because the first terminal device lacks the corresponding configuration to receive data packets forwarded by the second terminal device and encrypted using the pre-reestablishment key, the first terminal device will not receive data packets forwarded by the second terminal device and encrypted using the pre-reestablishment key of the access network device. Consequently, the first terminal device will not decrypt erroneous data.

[0016] In one possible implementation, the communication method further includes: receiving a second message from the access network device, the second message being used to indicate one or more added or modified wireless link control channel configurations; and releasing the wireless link control channel configuration between the first terminal device and the second terminal device.

[0017] When the access network device instructs the first terminal device to add or modify a radio link control channel configuration, the first terminal device processes the configuration according to the full configuration and releases all radio link control channel configurations between the first terminal device and the second terminal device. In this way, the first terminal device clears the data packets encrypted with the pre-reestablishment key cached on the first terminal device side. As a result, the access network device will not receive data packets forwarded by the second terminal device that were encrypted with the pre-reestablishment key from the first terminal device, and the access network device will not decrypt incorrect data.

[0018] In a second aspect, a communication method is provided. This communication method can be executed by a second terminal device, or by a chip or circuit for the second terminal device, although this application does not limit this. For ease of description, the following description uses execution by the second terminal device as an example. The second terminal device is configured to provide relay services for communication between the first terminal device and the access network device.

[0019] The communication method includes: sending a first message to a first terminal device, the first message being used to indicate that a wireless link failure occurs between a second terminal device and an access network device; and stopping sending data to the first terminal device, the data including data sent by the access network device to the first terminal device via the second terminal device.

[0020] In the technical solution provided in this application, when a wireless link failure occurs between a second terminal device and an access network device, the second terminal device sends a first message to the first terminal device, causing the second terminal device to stop sending downlink data to the first terminal device. Thus, during the reestablishment process between the first terminal device and the access network device, the second terminal device clears cached downlink data. Furthermore, after the reestablishment of the connection between the first terminal device and the access network device, the first terminal device will not receive data packets forwarded by the second terminal device that were encrypted using the pre-reestablishment key, thus preventing the first terminal device from decrypting erroneous data.

[0021] In one possible implementation, after stopping sending data to the first terminal device, the communication method further includes: sending a second request message to the access network device, where the second request message is used to request re-establishment of the connection between the second terminal device and the access network device.

[0022] Before the second terminal device requests reestablishment from the access network device, the first terminal device stops sending data to the first terminal device. Thus, while the second terminal device and the access network device are reestablishing, the first terminal device will not receive data packets forwarded by the second terminal device that were encrypted using the pre-reestablishment key. Furthermore, after the second terminal device and the access network device are reestablished, the first terminal device will not receive data packets forwarded by the second terminal device that were encrypted using the pre-reestablishment key, preventing the first terminal device from decrypting incorrect data.

[0023] In one possible implementation, the communication method further includes: releasing the second entity when a third condition is satisfied. The second entity is used by the second terminal device to send a message to the first terminal device; the third condition includes one of the following: the second terminal device detects a radio link failure between the second terminal device and the access network device; the second terminal device sends the first message; or the second terminal device sends the second request message.

[0024] When the second terminal device detects a wireless link failure between the second terminal device and the access network device, or the second terminal device sends a first message, or the second terminal device sends a second request message, the second terminal device releases the second entity. In this way, the second terminal device clears the data packets encrypted with the pre-reestablishment key cached on the second terminal device side. Then, after the first terminal device and the access network device are reestablished, the first terminal device will not receive data packets forwarded by the second terminal device that were encrypted with the pre-reestablishment key, and thus the first terminal device will not decrypt erroneous data.

[0025] In one possible implementation, the communication method further includes: releasing the second configuration when a fourth condition is met. The second configuration is configured for the second terminal device to receive a message from the first terminal device. The fourth condition includes one of the following: the second terminal device detecting a radio link failure between the second terminal device and the access network device; the second terminal device sending the first message; or the second terminal device sending the second request message.

[0026] When the second terminal device detects a wireless link failure between the second terminal device and the access network device, or when the second terminal device sends a first message, or when the second terminal device sends a second request message, the second terminal device releases the second configuration. This way, because the second terminal device lacks the corresponding configuration to receive data packets encrypted by the first terminal device using the pre-reestablishment key, the access network device will not receive data packets forwarded by the second terminal device and encrypted by the first terminal device using the pre-reestablishment key. Consequently, the access network device will not decrypt erroneous data.

[0027] In one possible implementation, the communication method further includes: receiving a third message from an access network device, the third message being used to indicate one or more added or modified wireless link control channel configurations; and releasing the wireless link control channel between the first terminal device and the second terminal device.

[0028] When the access network device instructs the second terminal device to add or modify the radio link control channel configuration, the second terminal device processes the configuration according to the full configuration and releases all radio link control channel configurations between the first terminal device and the second terminal device. In this way, the second terminal device clears the data packets encrypted with the pre-reestablishment key from the access device that were cached on the second terminal device side. Then, after the first terminal device and the access network device are reestablished, the first terminal device will not receive the data packets forwarded by the second terminal device that were encrypted with the pre-reestablishment key, and the first terminal device will not decrypt erroneous data.

[0029] In a third aspect, a communication method is provided. This communication method can be executed by a first terminal device, or alternatively, by a chip or circuit for the first terminal device, although this application does not limit this. For ease of description, the following description uses execution by the first terminal device as an example. The first terminal device communicates with an access network device via a second terminal device.

[0030] The communication method includes: receiving a first response message from an access network device, the first response message is used to indicate a second identifier and a second key; receiving first information from a second terminal device, the first information includes first data and a first identifier, the first data is encrypted using a first key, the first identifier is an identifier of the first terminal device, and the first identifier is used for a sidelink relay adaptation layer; and processing the first data using the first key.

[0031] In the technical solution provided in the present application, the first terminal device processes the received first data according to the first identifier, so that the first terminal device can avoid decoding an erroneous data packet.

[0032] In a possible implementation, processing the first data using the first key includes: decrypting the first data or discarding the first data according to the first identifier.

[0033] In a possible implementation, decrypting the first data or discarding the first data according to the first identifier includes: determining that the first data is encrypted using the first key according to the first identifier; and decrypting the first data or discarding the first data.

[0034] The first identifier carried by the first information is used to distinguish whether the first data carried by the first information is encrypted using the first key or the second key. In this way, the first terminal device determines whether the first data is encrypted using the first key based on the first identifier in the first information, and then uses the first key to decrypt the first data or discard the first data. In this way, the first terminal device can avoid decrypting the wrong data packet.

[0035] In a possible implementation, the communication method further includes: stopping sending data to the second terminal device, where the data includes data sent by the first terminal device to the access network device via the second terminal device.

[0036] The first terminal device processes the received first data based on the first identifier, and stops sending uplink data to the second terminal device. Thus, after the first terminal device reestablishes communication with the access network device, the access network device will not receive data packets forwarded by the second terminal device that are encrypted using the first key, and thus the access network device will not decrypt erroneous data.

[0037] In one possible implementation, the communication method further includes: sending a fourth message to the access network device, the fourth message being used to indicate that the connection between the first terminal device and the access network device has been reestablished; and releasing the first identifier.

[0038] After the first terminal device and the access network device complete the re-establishment, the first terminal device releases the first identifier and stops maintaining the first identifier, thereby reducing the overhead of the first terminal device.

[0039] In a possible implementation, the releasing the first local identifier includes: releasing the first identifier if the second information carrying the first identifier is not received within a preset time.

[0040] After the first terminal device and the access network device complete the re-establishment, if the second information carrying the first identifier is not received within the preset time, the first terminal device automatically releases the first identifier and automatically stops maintaining the first identifier, thereby reducing the overhead of the first terminal device.

[0041] In a fourth aspect, a communication method is provided. This communication method can be executed by a first terminal device, or can also be executed by a chip or circuit for the first terminal device, although this application does not limit this. For ease of description, the following description uses the first terminal device as an example. The first terminal device communicates with an access network device through a second terminal device.

[0042] The communication method includes: sending a first request message to a second terminal device, the first request message is used to request to re-establish the connection between the first terminal device and the access network device; re-establishing a third entity, the third entity is used for the first terminal device to send a message to the second terminal device; receiving first information from the second terminal device, the first information includes first data and a first identifier, the first data is encrypted using a first key, the first identifier is the identifier of the first terminal device, and the first identifier is used for the sidelink relay adaptation layer; and stopping processing the first data.

[0043] In the technical solution provided in this application, after a first terminal device sends a request to an access network device via a second terminal device to reestablish a connection between the first terminal device and the access network device, the first terminal device reestablishes the third entity on its own. However, because the first terminal device has not reestablished the configuration corresponding to the third entity or has not received an instruction from the access network device to establish the configuration corresponding to the third entity, the first terminal device stops processing the first data after receiving the first information, thereby preventing the first terminal device from decoding an erroneous data packet.

[0044] In one possible implementation, the first terminal device includes a third entity and a fourth entity, the fourth entity is a radio link control entity, and stopping processing the first data includes: the fourth entity stops submitting the first data to the third entity, or the fourth entity discards the first data.

[0045] In a possible implementation, the communication method further includes: stopping sending data to the second terminal device, where the data includes data sent by the first terminal device to the access network device via the second terminal device.

[0046] Because the first terminal device has not re-established the configuration corresponding to the third entity or the first terminal device has not received an instruction from the access network device to establish the configuration corresponding to the third entity, the first terminal device stops sending uplink data to the second terminal device. In this way, after the first terminal device and the access network device are re-established, the access network device will not receive data packets forwarded by the second terminal device that were encrypted using the key before re-establishment, and the access network device will not decrypt erroneous data.

[0047] In a fifth aspect, a communication method is provided. This communication method can be executed by a second terminal device, or can also be executed by a chip or circuit for the second terminal device, although this application does not limit this. For ease of description, the following description uses execution by the second terminal device as an example. The second terminal device is configured to provide relay services for communication between the first terminal device and the access network device.

[0048] The communication method includes: sending a second request message to the access network device, the second request message is used to request to re-establish the connection between the second terminal device and the access network device; reconstructing the fifth entity, the fifth entity is used for the second terminal device to forward the message transmitted between the first terminal device and the access network device; receiving third information from the first terminal device, the third information includes second data and a first identifier, the second data is encrypted with a first key, the first identifier is the identifier of the first terminal device, and the first identifier is used for the sidelink relay adaptation layer; and stopping processing the second data.

[0049] In the technical solution provided in this application, after the second terminal device sends a request to the access network device to reestablish the connection between the second terminal device and the access network device, the second terminal device reestablishes the fifth entity. However, because the second terminal device has not reestablished the configuration corresponding to the fifth entity or has not received an instruction from the access network device to establish the configuration corresponding to the fifth entity, the second terminal device stops processing the second data after receiving the third information. Furthermore, after the second terminal device and the access network device are reestablished, the access network device will not receive data packets forwarded by the second terminal device that are encrypted using the first key, and thus the access network device will not decrypt erroneous data.

[0050] In one possible implementation, the second terminal device includes a fifth entity and a sixth entity, the sixth entity is a radio link control entity, and stopping processing the second data includes: the sixth entity stops submitting the second data to the fifth entity, or the sixth entity discards the second data.

[0051] In a possible implementation, the communication method further includes: stopping sending data to the first terminal device, where the data includes data sent by the access network device to the first terminal device via the second terminal device.

[0052] In a sixth aspect, a communication method is provided. The communication method may be executed by an access network device, or may be executed by a chip or circuit for the access network device, which is not limited in this application. For ease of description, the following description is based on an example of execution by an access network device.

[0053] The communication method includes: sending a sixth message to a second terminal device, the sixth message being used to indicate a second identifier and a second key; receiving a third message from the second terminal device, the third message including second data and a first identifier, the second data being encrypted using a first key, the second terminal device being used to provide a relay service for communication between the first terminal device and an access network device; and processing the second data using the first key. The first identifier and the second identifier are identifiers of the first terminal device, and the first identifier and the second identifier are used by the sidelink relay adaptation layer.

[0054] In the technical solution provided in the present application, the access network device processes the received second data according to the first identifier, thereby preventing the access network device from decoding an erroneous data packet.

[0055] In a possible implementation, using the first key to process the second data includes: decrypting the second data or discarding the second data according to the first identifier.

[0056] In a possible implementation, decrypting the second data or discarding the second data according to the first identifier includes: determining that the second data is encrypted using the first key according to the first identifier; and decrypting the second data or discarding the second data.

[0057] The first identifier carried by the third information is used to distinguish whether the second data carried by the third information is encrypted using the first key or the second key. In this way, the access network device determines whether the second data is encrypted using the first key based on the first identifier in the third information, and then uses the first key to decrypt the second data or discard the second data. In this way, the access network device can avoid decrypting the wrong data packet.

[0058] In a seventh aspect, a communication method is provided. This communication method can be executed by a second terminal device, or can also be executed by a chip or circuit for the second terminal device, which is not limited in this application. For ease of description, the following description uses the second terminal device as an example. The second terminal device is used to provide relay services for communication between the first terminal device and the access network device.

[0059] The communication method includes: initiating reestablishment of a connection between a second terminal device and an access network device; releasing a first entity and a second entity; applying a first predefined configuration to a third entity; and applying a second predefined configuration to a fourth entity. The first entity and the third entity are used by the second terminal device to receive a first request message from the first terminal device, and the second entity and the fourth entity are used by the second terminal device to receive a fourth message from the first terminal device, wherein the first request message is used to request reestablishment of a connection between the first terminal device and the access network device, and the fourth message is used to indicate that the connection between the first terminal device and the access network device has been reestablished.

[0060] After the second terminal device initiates the re-establishment process between the second terminal device and the access network device, the second terminal device releases the entities of the second terminal device corresponding to the first pre-defined configuration and the second pre-defined configuration, and re-establishes the entities corresponding to the first pre-defined configuration and the second pre-defined configuration. In this way, the first terminal device sends the first request message and the fourth message to the access network device through the second terminal device. The sequence numbers of the entities of the first terminal device and the second terminal device both start at 0. Therefore, the second terminal device can correctly receive the first request message and the fourth message, and then forward them to the access network device, ensuring that the re-establishment process of the first terminal device proceeds normally.

[0061] In an eighth aspect, a communication device is provided. The communication device may be a first terminal device, or a chip or circuit of the first terminal device, which is not limited in this application.

[0062] The communication device includes: a transceiver unit for receiving a first message from a second terminal device, the first message being used to indicate a wireless link failure between the second terminal device and the access network device; a processing unit for stopping sending data to the second terminal device, the data including data sent by the first terminal device to the access network device via the second terminal device.

[0063] In a possible implementation, the transceiver unit is further used to send a first request message to the second terminal device, where the first request message is used to request to re-establish the connection between the first terminal device and the access network device.

[0064] In one possible implementation, the processing unit is further configured to release the first entity when a first condition is satisfied. The first entity is configured to enable a first terminal device to send a message to a second terminal device. The first condition includes the first terminal device receiving the first message or the first terminal device sending a first request message.

[0065] In one possible implementation, the processing unit is further configured to release the first configuration when a second condition is satisfied. The first configuration is configured for the first terminal device to receive a message from the second terminal device. The second condition includes the first terminal device receiving the first message or the first terminal device sending a first request message.

[0066] In one possible implementation, the transceiver unit is further used to receive a second message from the access network device, where the second message is used to indicate one or more added or modified wireless link control channel configurations; the processing unit is further used to release the wireless link control channel configuration between the first terminal device and the second terminal device.

[0067] The technical effects of any possible implementation method in the eighth aspect can refer to the technical effects of the corresponding implementation method of the first aspect, and will not be repeated here.

[0068] In a ninth aspect, a communication device is provided, which may be a second terminal device, or a chip or circuit of the second terminal device, and this application does not limit this.

[0069] The communication device includes: a transceiver unit, used to send a first message to a first terminal device, the first message is used to indicate that a wireless link failure occurs between a second terminal device and an access network device; a processing unit, used to stop sending data to the first terminal device, the data including data sent by the access network device to the first terminal device through the second terminal device.

[0070] In a possible implementation, the transceiver unit is further used to send a second request message to the access network device, where the second request message is used to request to re-establish the connection between the second terminal device and the access network device.

[0071] In one possible implementation, the processing unit is further configured to release the second entity when a third condition is satisfied. The second entity is configured to enable the second terminal device to send a message to the first terminal device; the third condition includes one of the following: the second terminal device detecting a radio link failure between the second terminal device and the access network device; the second terminal device sending the first message; or the second terminal device sending the second request message.

[0072] In one possible implementation, the processing unit is further configured to release the second configuration when a fourth condition is satisfied. The second configuration is configured for the second terminal device to receive a message from the first terminal device. The fourth condition includes one of the following: the second terminal device detecting a radio link failure between the second terminal device and the access network device; the second terminal device sending the first message; or the second terminal device sending the second request message.

[0073] In one possible implementation, the transceiver unit is also used to receive a third message from the access network device, where the third message is used to indicate one or more added or modified wireless link control channel configurations; the processing unit is also used to release the wireless link control channel configuration between the first terminal device and the second terminal device.

[0074] The technical effects of any possible implementation method of the ninth aspect can refer to the technical effects of the corresponding implementation method of the second aspect, and will not be repeated here.

[0075] In the tenth aspect, a communication device is provided, which may be a first terminal device, or a chip or circuit of the first terminal device, and this application does not limit this.

[0076] The communication device includes: a transceiver unit, used to receive first information from a second terminal device, the first information includes first data and a first identifier, the first data is encrypted using a first key, the first identifier is an identifier of the first terminal device, and the first identifier is used for a sidelink relay adaptation layer; the transceiver unit is also used to receive a first response message from an access network device, the first response message is used to indicate a second identifier and a second key; a processing unit is used to process the first data using the first key.

[0077] In a possible implementation, processing the first data using the first key includes: decrypting the first data or discarding the first data according to the first identifier.

[0078] In a possible implementation, the processing unit is further configured to determine, based on the first identifier, whether the first data is encrypted using the first key; and decrypt the first data or discard the first data.

[0079] In a possible implementation, the transceiver unit is further configured to stop sending data to the second terminal device, where the data includes data sent by the first terminal device to the access network device via the second terminal device.

[0080] In one possible implementation, the transceiver unit is further used to send a fourth message to the access network device, where the fourth message is used to indicate that the connection between the first terminal device and the access network device has been reestablished; and the processing unit is further used to release the first identifier.

[0081] In a possible implementation manner, the processing unit is further specifically configured to release the first identifier if the second information carrying the first identifier is not received within a preset time.

[0082] After the first terminal device and the access network device complete the re-establishment, if the second information carrying the first identifier is not received within the preset time, the first terminal device automatically releases the first identifier and automatically stops maintaining the first identifier, thereby reducing the overhead of the first terminal device.

[0083] The technical effects of any possible implementation method of the tenth aspect can refer to the technical effects of the corresponding implementation method of the third aspect, and will not be repeated here.

[0084] In the eleventh aspect, a communication device is provided, which may be a first terminal device, or a chip or circuit of the first terminal device, which is not limited in this application.

[0085] The communication device includes: a transceiver unit, used to send a first request message to the second terminal device, the first request message is used to request to re-establish the connection between the first terminal device and the access network device; a processing unit, used to reconstruct the third entity, the third entity is used for the first terminal device to send a message to the second terminal device; the transceiver unit is used to receive first information from the second terminal device, the first information includes first data and a first identifier, the first data is encrypted using a first key, the first identifier is the identifier of the first terminal device, and the first identifier is used for the sidelink relay adaptation layer; the processing unit is also used to stop processing the first data.

[0086] In one possible implementation, the communication device also includes a third entity and a fourth entity, the fourth entity is a wireless link control entity, and the processing unit is specifically used to stop delivering the first data to the third entity through the fourth entity, or to discard the first data through the fourth entity.

[0087] In a possible implementation, the transceiver unit is further configured to stop sending data to the second terminal device, where the data includes data sent by the first terminal device to the access network device via the second terminal device.

[0088] The technical effects of any possible implementation method in the eleventh aspect can refer to the technical effects of the corresponding implementation method of the fourth aspect, and will not be repeated here.

[0089] In the twelfth aspect, a communication device is provided, which may be a second terminal device, or a chip or circuit of the second terminal device, which is not limited in this application.

[0090] The communication device includes: a transceiver unit, used to send a second request message to the access network device, the second request message is used to request to re-establish the connection between the second terminal device and the access network device; a processing unit, used to reconstruct the fifth entity, the fifth entity is used for the second terminal device to forward the message transmitted between the first terminal device and the access network device; the transceiver unit is also used to receive third information from the first terminal device, the third information includes second data and a first identifier, the second data is encrypted with a first key, the first identifier is the identifier of the first terminal device, and the first identifier is used for the sidelink relay adaptation layer; the processing unit is also used to stop processing the second data.

[0091] In one possible implementation, the communication device further includes: a processing unit configured to reestablish a fifth entity, the fifth entity being configured to forward, via the second terminal device, messages transmitted between the first terminal device and the access network device. The communication device further includes the fifth entity and a sixth entity, the sixth entity being a radio link control entity. The processing unit is further configured to stop delivering the second data to the fifth entity via the sixth entity, or to discard the second data via the sixth entity.

[0092] In a possible implementation, the transceiver unit is further configured to stop sending data to the first terminal device, where the data includes data sent by the access network device to the first terminal device via the second terminal device.

[0093] In the thirteenth aspect, a communication device is provided, which may be an access network device, or a chip or circuit of an access network device, which is not limited in this application.

[0094] The communication device includes: a transceiver unit configured to send a sixth message to a second terminal device, the sixth message indicating a second identifier and a second key; a transceiver unit configured to receive third information from the second terminal device, the third information including second data and a first identifier, the second data encrypted using a first key, the second terminal device configured to provide a relay service for communication between the first terminal device and an access network device; and a processing unit configured to process the second data using the first key. The first identifier and the second identifier are identifiers of the first terminal device, and the first identifier and the second identifier are used by the sidelink relay adaptation layer.

[0095] In a possible implementation, the processing unit is further configured to decrypt the second data or discard the second data according to the first identifier.

[0096] In a possible implementation, the processing unit is further specifically configured to: determine, based on the first identifier, that the second data is encrypted using the first key; and decrypt the second data or discard the second data.

[0097] The technical effects of any possible implementation method of the thirteenth aspect can refer to the technical effects of the corresponding implementation method of the sixth aspect, and will not be repeated here.

[0098] In the fourteenth aspect, a communication device is provided, which may be a second terminal device, or a chip or circuit of the second terminal device, which is not limited in this application.

[0099] The communication device includes: a processing unit, configured to: initiate reestablishment of a connection between a second terminal device and an access network device; release a first entity and a second entity; apply a first predefined configuration to a third entity; and apply a second predefined configuration to a fourth entity. The first entity and the third entity are configured to enable the second terminal device to receive a first request message from the first terminal device, and the second entity and the fourth entity are configured to enable the second terminal device to receive a fourth message from the first terminal device. The first request message is configured to request reestablishment of a connection between the first terminal device and the access network device, and the fourth message is configured to indicate that the connection between the first terminal device and the access network device has been reestablished.

[0100] The technical effects of any possible implementation method of the fourteenth aspect can refer to the technical effects of the corresponding implementation method of the seventh aspect, and will not be repeated here.

[0101] In the fifteenth aspect, a communication device is provided, comprising: at least one processor, the at least one processor being coupled to at least one memory, the at least one processor being used to execute a computer program or instruction stored in the at least one memory, so that the communication device executes the communication method in any possible implementation of the above-mentioned first to seventh aspects.

[0102] In a sixteenth aspect, a processor is provided for executing the communication method in any possible implementation of the first to seventh aspects above.

[0103] For the operations such as sending and acquiring / receiving involved in the processor, unless otherwise specified, or if they do not conflict with their actual functions or internal logic in the relevant descriptions, they can be understood as processor output, reception, input and other operations, and can also be understood as sending and receiving operations performed by the radio frequency circuit and antenna. This application does not limit this.

[0104] In the seventeenth aspect, a chip system is provided, comprising: a processor for calling and running a computer program from a memory, so that a communication device equipped with the chip system executes a communication method in any possible implementation of the first to seventh aspects above.

[0105] Optionally, as an implementation method, the chip also includes a memory, in which a computer program or instruction is stored, and the processor is used to execute the computer program or instruction stored in the memory. When the computer program or instruction is executed, the processor is used to execute the communication method in any possible implementation of the first to seventh aspects above.

[0106] In the eighteenth aspect, a computer program product comprising instructions is provided, which, when run on a communication device, enables the communication device to execute a communication method in any possible implementation of the first to seventh aspects.

[0107] In a nineteenth aspect, a computer-readable storage medium is provided, which stores a program code for execution by a device, wherein the program code includes instructions for executing a communication method provided by any possible implementation of the first to seventh aspects.

[0108] In the twentieth aspect, a chip is provided, comprising at least one processor and a communication interface, wherein the communication interface is used to receive data and / or information and transmit the received data and / or information to the processor, and the processor processes the data and / or information to execute the communication method in any possible implementation of the first to seventh aspects above.

[0109] In a twenty-first aspect, a communication system is provided, comprising a first terminal device and a second terminal device, wherein the first terminal device is configured to execute the communication method in any possible implementation of the first aspect; and the second terminal device is configured to execute the communication method in any possible implementation of the second aspect.

[0110] In a twenty-second aspect, a communication system is provided, comprising a first terminal device and at least one of the following: a second terminal device and an access network device. The first terminal device is configured to execute the communication method of any possible implementation of the third aspect; or the first terminal device is configured to execute the communication method of any possible implementation of the fourth aspect.

[0111] In a twenty-third aspect, a communication system is provided, comprising a second terminal device and an access network terminal device. The second terminal device is configured to execute the communication method of any possible implementation of the fifth aspect, and the access network device is configured to execute the communication method of any possible implementation of the sixth aspect.

[0112] In a twenty-fourth aspect, a communication system is provided, comprising a first terminal device, a second terminal device, and an access network device, wherein the access network device is configured to execute the communication method in any possible implementation of the seventh aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0113] FIG1 is a schematic diagram of the architecture of an example of a communication system applicable to an embodiment of the present application.

[0114] FIG2 is a schematic diagram of a protocol stack of the communication system shown in FIG1 based on L2.

[0115] FIG3 is a schematic flowchart of a communication method provided in an embodiment of the present application.

[0116] FIG4 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0117] FIG5 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0118] FIG6 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0119] FIG7 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0120] FIG8 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0121] FIG9 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0122] FIG10 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0123] FIG11 is a schematic flowchart of another communication method provided in an embodiment of the present application.

[0124] FIG12 is a schematic structural diagram of a communication device provided in an embodiment of the present application.

[0125] FIG13 is a schematic block diagram of another communication device provided in an embodiment of the present application.

[0126] Figure 14 is a schematic block diagram of a chip system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0127] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0128] In order to facilitate understanding of the embodiments of the present application, the following explanations are made before introducing the embodiments of the present application.

[0129] First, in the embodiment of the present application, "indication" may include direct indication and indirect indication, and may also include explicit indication and implicit indication. The information indicated by a certain signal (such as the first information described below) is called information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated, such as but not limited to, the information to be indicated can be directly indicated, such as the information to be indicated itself or the index of the information to be indicated. The information to be indicated can also be indirectly indicated by indicating other information, wherein the other information and the information to be indicated have an association relationship. It is also possible to indicate only a part of the information to be indicated, while the other parts of the information to be indicated are known or agreed in advance. For example, the indication of specific information can also be achieved by means of the arrangement order of each information agreed in advance (such as specified in the protocol), thereby reducing the indication overhead to a certain extent.

[0130] Second, in the embodiments shown below, the first, second, and various numbers are only used for the convenience of description and are not intended to limit the scope of the embodiments of the present application. For example, to distinguish different messages, information, etc.

[0131] Third, the “multiple” involved in the embodiments of the present application generally refers to two or more.

[0132] Fourth, in the various embodiments of the present application, unless otherwise specified or provided by law, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0133] In a wireless communication system, terminal devices can communicate data with each other through access network devices, or they can communicate directly with each other without the help of access network devices, which can effectively reduce communication delays.

[0134] The interface between terminal devices is called a PC5 interface, which is similar to the Uu interface between a terminal device and an access network device.

[0135] The link between terminal devices is called SL. A typical application scenario of SL communication is vehicle-to-everything (V2X). In V2X, each vehicle can be considered as a terminal device.

[0136] SL supports broadcast, unicast, and multicast communications. The following describes each of these.

[0137] (1) Broadcast communications

[0138] Similar to the access network device broadcast system information, that is, the terminal device sends the broadcast service data to the outside without encryption. Any other terminal device within the effective receiving range can receive the broadcast service data if it is interested in the broadcast service.

[0139] (2) Unicast communication

[0140] This is similar to data communication between a terminal device and an access network device after establishing a radio resource control (RRC) connection. In unicast communication, two terminal devices need to first establish a unicast connection. After the unicast connection is established, the two terminal devices communicate data based on negotiated identifiers (such as the source L2 ID and destination L2 ID described below).

[0141] A unicast communication on the SL corresponds to a pair of IDs: a source layer 2 identifier (L2 ID) and a destination layer 2 identifier (Destination L2 ID). The subheader of each SL media access control protocol data unit (MAC PDU) contains partial bytes of the source L2 ID and the destination L2 ID to ensure that the data is transmitted to the correct receiving end.

[0142] The data transmitted between two terminal devices can be encrypted or unencrypted. Compared with broadcast communication, unicast communication can only be carried out between two terminal devices that have established a unicast connection.

[0143] (3)Multicast communication

[0144] Refers to the communication between all terminal devices in a communication group. Any terminal device in the group can send and receive data of the multicast service.

[0145] Radio bearer (RB): A radio bearer is a collective term for a series of protocol entities and configurations allocated by access network equipment to a UE. It is a Layer 2 service used to transmit user data between the UE and the base station. It includes resources allocated by the packet data convergence protocol (PDCP), radio link control (RLC), medium access control (MAC), and physical layer (PHY) protocol entities. Radio bearers are categorized as data radio bearers (DRBs) and signaling radio bearers (SRBs). The former carries data, while the latter carries signaling messages.

[0146] The U2N relay communication system provided in the embodiment of the present application is introduced below with reference to FIG1 and FIG2.

[0147] FIG1 is a schematic diagram of the architecture of an example of a communication system applicable to an embodiment of the present application.

[0148] For example, as shown in Figure 1, a U2N relay communication system 100 includes: a first terminal device (also referred to as a remote UE), at least one second terminal device (also referred to as a relay UE), and an access network device. The second terminal device is configured to provide a relay service for communication between the first terminal device and the access network device.

[0149] In the communication system 100, the second terminal device communicates with the first terminal device via a sidelink (SL) (eg, a PC5 interface), and the second terminal device communicates with the access network device via an air interface (eg, a Uu interface).

[0150] It should be understood that the second terminal device and the first terminal device (hereinafter collectively referred to as terminal devices) are a type of device with wireless transceiver functions, which may refer to user equipment (UE), access terminal, subscriber unit, user station, mobile station, remote station, remote terminal, mobile device, user terminal, wireless communication device, user agent or user device. The terminal device 120 may also be a satellite phone, a cellular phone, a smart phone, a wireless data card, a wireless modem, a machine type communication device, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a customer-premises equipment (CPE), a smart point of sale (POS) machine, a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, an in-vehicle device, a communication device carried on a high-altitude aircraft, a wearable device, a drone, a robot, a terminal in device-to-device (D2D) communication, a terminal in vehicle-to-everything (V2X), a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a remote medical device, or a similar device. This application does not limit the wireless terminals in medical, smart grid, transportation safety, smart city, smart home, or terminal devices in communication networks evolved after 5G.

[0151] The communication device used to implement the functions of the terminal device can be the terminal device, or it can be a device that can support the terminal device to implement the functions, such as a chip system. The device can be installed in the terminal device or used in conjunction with the terminal device. In this application, the chip system can be composed of a chip or include a chip and other discrete devices.

[0152] Access network equipment is a device with wireless transceiver functions used to communicate with terminal devices. Access network equipment can be a node in the radio access network (RAN), which can be called a base station or a RAN node. It can be an evolved Node B (eNB or eNodeB) of long term evolution (LTE); or a base station of a 5G network such as gNodeB (gNB) or a base station in a public land mobile network (PLMN) evolved after 5G, a broadband network gateway (BNG), an aggregation switch or the 3rd generation partnership project (3GPP) access equipment, etc.

[0153] The RAN can be configured as a RAN defined by the 3GPP protocol, an open radio access network (O-RAN), or a cloud radio access network (C-RAN). The access network device 110 can also include various forms of base stations, such as macro base stations, micro base stations (also known as small stations), relay stations, transmission points (transmitting and receiving points, TRP), transmission points (transmitting points, TP), mobile switching centers, and devices that perform base station functions in device-to-device (D2D), vehicle-to-everything (V2X), and machine-to-machine (M2M) communications, access network devices in non-terrestrial networks (NTN), etc., without specific limitation.

[0154] The access network equipment may also include network elements or modules that implement some functions of the base station, such as one or more of the following: a centralized unit (CU), a distributed unit (DU), or a radio unit (RU). Optionally, the CU can be further separated into a CU-control plane (CP) and a CU-user plane (UP). The functions of the CU and DU can be implemented by different network elements, or simultaneously by the baseband unit (BBU) of the base station. The functions of the RU can be implemented by the radio frequency equipment of the base station. For example, the radio frequency equipment of the base station may be a remote radio unit (RRU), a pico remote radio unit (pRRU), an active antenna unit (AAU), or other units, modules or devices with radio frequency processing functions. The communication interface protocol between the BBU and the radio frequency equipment can be a common public radio interface (CPRI) interface protocol, an enhanced common public radio interface (eCPRI) interface protocol, or a fronthaul interface protocol between the DU and RU in the O-RAN system, etc., without limitation.

[0155] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meanings. For example, in the ORAN system, CU may also be called O-CU (Open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples for description.

[0156] The communication device used to implement the functions of the access network device can be the access network device, or it can be a device that can support the access network device to implement the functions, such as a chip system. The device can be installed in the access network device or used in conjunction with the access network device. The chip system in the embodiments of the present application can be composed of a chip, or it can include a chip and other discrete devices.

[0157] The communication system 100 may also be the following systems: long term evolution (LTE) system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD) system, universal mobile telecommunication system (UMTS), 5G system, 6G system, inter-satellite communication, satellite communication and other NTN systems. Among them, the satellite communication system includes a satellite base station and terminal equipment. The satellite base station provides communication services for the terminal equipment. The satellite base station can also communicate with the ground base station. The satellite can be used as a base station or as a terminal device. Among them, the satellite can refer to non-ground base stations or non-ground equipment such as drones, hot air balloons, low-orbit satellites, medium-orbit satellites, and high-orbit satellites.

[0158] The communication system 100 may also be a terrestrial cellular communication system, a high altitude platform station (HAPS) communication system, a V2X system, an integrated access and backhaul (IAB) system, and a reconfigurable intelligent surface (RIS) communication system, etc., without limitation.

[0159] It should be understood that FIG1 is only a simplified schematic diagram for ease of understanding, and the communication system may also include other devices that are not shown in FIG1 .

[0160] Currently, there are two possible implementations of U2N relay technology: Layer 3 (L3) relay and L2 relay. In the L2 relay method, user plane data is forwarded below the PDCP layer. The user plane protocol stack is shown in Figure 2.

[0161] FIG2 is a schematic diagram of a protocol stack of the communication system shown in FIG1 based on L2.

[0162] For example, as shown in Figure 2, the user plane protocol stack of the first terminal device includes: Uu-PDCP layer, PC5 relay adaptation protocol (sidelink relay adaptation protocol, PC5-SRAP) layer, PC5-RLC layer, PC5-MAC layer, and PC5-PHY layer. The user plane protocol stack of the second terminal device includes: PC5-SRAP layer, PC5-RLC layer, PC5-MAC layer, PC5-PHY layer, Uu-SRAP layer, Uu-RLC layer, Uu-MAC layer, and Uu-PHY layer. The user plane protocol stack of the access network device includes: Uu-PDCP layer, Uu-SRAP layer, Uu-RLC layer, Uu-MAC layer, and Uu-PHY layer.

[0163] Data packets from the first terminal device are relayed below the PDCP layer of the second terminal device. This means the second terminal device only maintains the relayed RLC bearer, which includes the RLC, MAC, and PHY layers. Therefore, there is an end-to-end Uu-PDCP layer between the first terminal device and the access network device, but no end-to-end RLC, MAC, or PHY layers.

[0164] In addition, the protocol architecture shown in Figure 2 adds PC5-SRAP between the RLC and PDCP layers. The PC5-SRAP layer's primary function is to multiplex and demultiplex bearers, enabling multiplexing of different bearers onto a single bearer or splitting a single bearer into different bearers, as well as distinguishing data from different first terminal devices. The SRAP layer in the protocol stack at both ends of the PC5 interface is called PC5-SRAP, while the SRAP layer in the protocol stack at both ends of the Uu interface is called Uu-SRAP.

[0165] In the U2N relay scenario, data forwarding is achieved through SRAP configuration. The access network device will configure the mapping relationship between DRB and PC5 RLC channel (PC5 RLC channel) and the local ID (local ID) for the first terminal device, and the first terminal device will send uplink data according to this configuration. Correspondingly, the access network device will configure the mapping relationship between DRB and Uu RLC channel (Uu RLC channel) and the local ID of the first terminal device for the second terminal device, and the second terminal device will forward uplink data according to this configuration. The access network device will configure the mapping relationship between DRB and PC5 RLC channel and the local ID of the first terminal device for the second terminal device, and the second terminal device will forward downlink data according to this configuration.

[0166] For uplink transmission, the SRAP header of the data packet carries the local ID and the bearer identifier (BEARER ID). After the second terminal device receives the data packet from the first terminal device, it determines that the data packet comes from the first terminal device based on the local ID. It further forwards the data packet to the access network device based on the mapping relationship between the DRB and the Uu RLC channel. The access network device delivers the data packet to the corresponding PDCP entity based on the BEARER ID. For downlink transmission, the SRAP header of the data packet carries the local ID and the BEARER ID. After the second terminal device receives the data packet from the access network device, it determines that the data packet is to be forwarded to the first terminal device based on the local ID. It further forwards the data packet to the first terminal device based on the mapping relationship between the DRB and the PC5 RLC channel. The first terminal device delivers the data packet to the corresponding PDCP entity based on the BEARER ID.

[0167] In the U2N relay scenario, if a radio link failure (RLF) is sent on the Uu port between the second terminal device and the access network device, the second terminal device will send a sidelink notification message to the first terminal device, indicating that an RLF has occurred in the Uu of the second terminal device. After receiving the message, the first terminal device will execute the RRC connection re-establishment process. During this process, the first terminal device will release the SRAP entity and SRAP configuration. Similarly, the second terminal device will also trigger the RRC connection re-establishment process and release the SRAP entity and SRAP config accordingly.

[0168] Since the entities and configurations of the RLC layer and the layers below RLC of the first terminal device and the second terminal device have not been released, the first terminal device can still send data packets on the PC5 RLC channel during the process of the second terminal device re-establishing the RRC connection, that is, the data packets submitted to the RLC layer and the layers below RLC before the first terminal device triggers the RRC re-establishment. These data packets are encrypted by the original key, where the original key refers to the key used by the second terminal device to decrypt the data packets before the RRC connection is re-established. After the second terminal device re-establishes the RRC connection, the access network device will send configuration information, and the second terminal device will create a new SRAP entity based on the configuration information and forward these data packets to the access network device. During the process of re-establishing the RRC connection of the first terminal device, the access network device will update the key. Therefore, when the access network device receives these data packets encrypted with the original key, it will use the new key to decrypt the erroneous data.

[0169] Based on this, an embodiment of the present application provides a communication method as shown in Figures 3 to 10, and the communication method shown in Figures 3 to 10 is applied to the U2N relay communication system 100 shown in Figure 1. The communication method includes a first terminal device, one or more second terminal devices, and an access network device. Among them, the first terminal device communicates with the access network device through one or more second terminal devices, or one or more second terminal devices provide relay services for the communication between the first terminal device and the access network device. The communication method provided in the embodiment of the present application is described in detail below in conjunction with Figures 3 to 10.

[0170] The interaction flow chart in this application uses the first terminal device, the second terminal device, and the access network device as examples of the execution subjects of the interaction diagram to illustrate the corresponding method, but this application does not limit the execution subjects of the interaction diagram. For example, the first terminal device in the figure can also be a chip, a chip system, or a processor that supports the first terminal device to implement the corresponding method, or a logic module or software that can implement all or part of the functions of the first terminal device; the second terminal device in the figure can also be a chip, a chip system, or a processor that supports the second terminal device to implement the corresponding method, or a logic module or software that can implement all or part of the functions of the second terminal device. The access network device in the figure can also be a chip, a chip system, or a processor that supports the access network device to implement the corresponding method, or a logic module or software that can implement all or part of the functions of the access network device.

[0171] FIG3 is a schematic flowchart of a communication method 300 provided in an embodiment of the present application.

[0172] As shown in Figure 3, the communication method 300 includes S301 and S302. S301 and S302 are described in detail below.

[0173] S301: A second terminal device sends a first message to a first terminal device, where the first message indicates that a radio link failure has occurred between the second terminal device and an access network device. Correspondingly, the first terminal device receives a sidelink notification message sent by the second terminal device.

[0174] Exemplarily, the first message may be a sidelink notification message.

[0175] The triggering condition of S301 may be that the second terminal device detects that a radio link failure (RLF) occurs on the Uu interface between the second terminal device and the access network device.

[0176] S302: The first terminal device stops sending data to the second terminal device, wherein the data includes data sent by the first terminal device to the access network device via the second terminal device.

[0177] In some embodiments, the first terminal device stops sending data to the second terminal device, including each protocol layer entity of the first terminal device stops processing data and does not deliver PDU to the lower layer.

[0178] For example, the protocol layer of the first terminal device includes the Uu-PDCP layer, PC5-SRAP layer, PC5-RLC layer, PC5-MAC layer, and PC5-PHY layer as shown in Figure 2, wherein the lower layer of the Uu-PDCP layer includes the PC5-SRAP layer, the lower layer of the PC5-SRAP layer includes the PC5-RLC layer, the lower layer of the PC5-RLC layer includes the PC5-MAC layer, and the lower layer of the PC5-MAC layer includes the PC5-PHY layer. The various protocol layer entities of the first terminal device stop processing data, that is, the Uu-PDCP layer, PC5-SRAP layer, PC5-RLC layer, PC5-MAC layer, and PC5-PHY layer of the first terminal device stop processing data respectively. The various protocol layer entities of the first terminal device do not submit PDUs to the lower layers, that is, the Uu-PDCP layer entity of the first terminal device does not submit PDUs to the PC5-SRAP layer, the PC5-SRAP layer entity of the first terminal device does not submit PDUs to the PC5-RLC layer, the PC5-RLC layer entity of the first terminal device does not submit PDUs to the PC5-MAC layer, and the PC5-MAC layer entity of the first terminal device does not submit PDUs to the PC5-PHY layer.

[0179] In some embodiments, the first terminal device ceasing to transmit data to the second terminal device includes the first terminal device releasing a first entity. The first entity is used by the first terminal device to transmit messages to the second terminal device. For example, the first entity may be an RLC entity. Thus, since the first terminal device releases the first entity, the first terminal device clears the uplink data cached on the first terminal device side, and the first terminal device no longer transmits uplink data to the second terminal device.

[0180] Furthermore, in some embodiments, the first terminal device stopping sending data to the second terminal device further includes: re-establishing an entity of the same type as the first entity; and performing a MAC reset. Re-establishing the entity of the same type as the first entity is performed after the first terminal device releases the first entity.

[0181] For example, the first terminal device releases the RLC entity, re-establishes the RLC entity, and releases the MAC layer related configuration.

[0182] Through S301 and S302, if an RLF occurs on the Uu interface of the second terminal device, the first terminal device, after receiving the first message sent by the second terminal device, stops uplink data transmission or the various protocol layer entities of the first terminal device stop processing data, and does not submit PDUs to the lower layer. In this way, during the RRC reestablishment process of the first terminal device, the first terminal device clears the cached uplink data. Therefore, after the first terminal device reestablishes RRC, the access network device will not receive data packets encrypted with the original key, and thus will not decrypt erroneous data.

[0183] In some embodiments, the first terminal device may also clear uplink data cached on the first terminal device side.

[0184] In some embodiments, the first terminal device clearing the uplink data cached on the first terminal device side includes the first terminal device reestablishing the first entity. Here, the first terminal device can be considered to have the function of reestablishing the first entity of the PC5 of the first terminal device and the second terminal device. For example, the first terminal device clearing the uplink data cached on the first terminal device side includes the first terminal device reestablishing the RLC entity.

[0185] In some other embodiments, the first terminal device clearing the uplink data cached on the first terminal device side includes: the first terminal device releasing the first entity; and the first terminal device reestablishing an entity of the same type as the first entity. For example, the first terminal device clearing the uplink data cached on the first terminal device side includes the first terminal device releasing the RLC entity and reestablishing the RLC entity.

[0186] Optionally, in some embodiments, when the first condition is met, the first terminal device clears the uplink data cached on the first terminal device side, that is, when the first condition is met, the first terminal device rebuilds the first entity or the first terminal device releases the first entity.

[0187] The first condition includes the first terminal device receiving the first message or sending the first request message. In other words, when the first terminal device receives the first message or sends the first request message, the first terminal device reestablishes the first entity or releases the first entity. For the relevant description of the first entity, please refer to the above and will not be repeated here. For the relevant description of the first request message, please refer to the relevant description in S303a below and will not be repeated here.

[0188] Furthermore, in some embodiments, after the first terminal device reestablishes the first entity or reestablishes an entity of the same type as the first entity, the first terminal device performs a MAC reset. MAC reset can be understood as releasing MAC layer-related configurations.

[0189] It should be noted that if the first terminal device stops sending data to the second terminal device in S302, including the first terminal device releasing the first entity, the first terminal device no longer needs to clear the uplink data cached on the first terminal device side. If the first terminal device stops sending data to the second terminal device in S302, including the first terminal device releasing the first entity, after S302, the first terminal device clears the uplink data cached on the first terminal device side.

[0190] In some embodiments, the first terminal device may also stop receiving data from the second terminal device, including data sent by the access network device to the first terminal device via the second terminal device. This prevents the first terminal device from receiving data packets encrypted with the original key from the access network device during the process of re-establishing a connection with the access network device, thereby preventing the first terminal device from decrypting erroneous data using the new key after the connection with the access network device is re-established.

[0191] Specifically, when a second condition is met, the first terminal device releases the first configuration. The first configuration is used for the first terminal device to receive a message from the second terminal device. The second condition includes the first terminal device receiving the first message or the first terminal device sending a first request message. In other words, when the first terminal device receives the first message or sends the first request message, the first terminal device releases the first configuration.

[0192] Exemplarily, the first configuration is allocated by the second terminal device to the first terminal device. The first configuration may include an RLC mode, an RLC sequence number, a logical channel identifier, and the like.

[0193] FIG4 is a schematic flowchart of another communication method 400 provided in an embodiment of the present application.

[0194] Optionally, in some embodiments, as shown in FIG4 , in addition to S301 and S302, communication method 400 may further include S303a, S303b, S304a, S304b, S305a, S305b, S306a, S306b, S307, and S401 to S406. S303a, S303b, S304a, S304b, S305a, S305b, S306a, S306b, and S307 are processes for reestablishing a connection between the first terminal device and the access network device. S402 to S406 are processes for reestablishing a connection between the second terminal device and the access network device. This application does not specify the order in which S303a is executed, or whether it is executed simultaneously, with S302, S401, S402, S403, S404, S405, and S406. It also does not specify the order in which S302 to S401 are executed, or whether they are executed simultaneously. S303b is executed after S405, and S401 is optional. The following describes in detail the steps of communication method 400 other than S301 and S302.

[0195] S401: The second terminal device stops sending data to the first terminal device, wherein the data includes data sent by the access network device to the first terminal device via the second terminal device.

[0196] In some embodiments, the second terminal device stops sending data to the first terminal device, including each protocol layer entity of the second terminal device stops processing data and does not deliver PDU to the lower layer.

[0197] For example, the protocol layer of the second terminal device includes the PC5-SRAP layer, PC5-RLC layer, PC5-MAC layer, and PC5-PHY layer as shown in Figure 2. The various protocol layer entities of the second terminal device stop processing data, that is, the PC5-SRAP layer, PC5-RLC layer, PC5-MAC layer, and PC5-PHY layer of the second terminal device stop processing data respectively. The various protocol layer entities of the second terminal device do not deliver PDUs to the lower layer, that is, the PC5-SRAP layer entity of the second terminal device does not deliver PDUs to the PC5-RLC layer, the PC5-RLC layer entity of the second terminal device does not deliver PDUs to the PC5-MAC layer, and the PC5-MAC layer entity of the second terminal device does not deliver PDUs to the PC5-PHY layer.

[0198] In some embodiments, the second terminal device ceasing to transmit data to the first terminal device includes the second terminal device releasing a second entity. The second entity is used by the second terminal device to transmit messages to the first terminal device. For example, the second entity may be an RLC entity. Thus, because the second terminal device releases the second entity, downlink data cached on the second terminal device side has no corresponding second entity to transmit. Therefore, the second terminal device will not transmit downlink data to the first terminal device, and the second terminal device will clear the downlink data cached on the second terminal device side.

[0199] In some embodiments, the second terminal device may also clear downlink data cached on the second terminal device side.

[0200] In some embodiments, the second terminal device clearing the uplink data cached on the second terminal device side includes the second terminal device reestablishing the second entity. Here, the second terminal device can be considered to have the function of reestablishing the second entity of PC5 of the first terminal device and the second terminal device. For example, the second terminal device clearing the downlink data cached on the second terminal device side includes the second terminal device reestablishing the RLC entity.

[0201] In some other embodiments, the second terminal device clearing the downlink data cached on the second terminal device side includes: the second terminal device releasing the second entity; and the second terminal device reestablishing an entity of the same type as the second entity. For example, the second terminal device clearing the downlink data cached on the second terminal device side includes the second terminal device releasing the RLC entity and reestablishing the RLC entity.

[0202] Optionally, in some embodiments, when the third condition is met, the second terminal device clears the downlink data cached on the second terminal device side, that is, when the third condition is met, the second terminal device rebuilds the second entity or the second terminal device releases the second entity.

[0203] Among them, the third condition includes one of the following: the second terminal device detects that a wireless link failure occurs between the second terminal device and the access network device; the second terminal device sends a first message; the second terminal device sends a second request message. In other words, when the second terminal device detects that a wireless link failure occurs between the second terminal device and the access network device, when the second terminal device sends the first message, or when the second terminal device sends the second request message, the second terminal device re-establishes the second entity or the second terminal device releases the second entity. For the relevant description of the second entity, please refer to the above and will not be repeated here. For the second request message, please refer to the relevant description in S402 below and will not be repeated here.

[0204] Furthermore, in some embodiments, after the second terminal device reestablishes the second entity or reestablishes an entity of the same type as the second entity, the second terminal device performs a MAC reset, which can be understood as releasing MAC layer-related configurations.

[0205] It should be noted that if the second terminal device stops sending data to the first terminal device in S401, including the second terminal device releasing the second entity, the second terminal device does not need to clear the downlink data cached on the second terminal device side. If the second terminal device stops sending data to the second terminal device in S401, including the second terminal device releasing the second entity, after S401, the second terminal device clears the downlink data cached on the second terminal device side.

[0206] In some embodiments, the second terminal device may also stop receiving data from the first terminal device, including data sent by the first terminal device to the access network device via the second terminal device. This prevents the second terminal device from forwarding data packets received from the first terminal device, encrypted using the original key, to the access network device during the process of reestablishing a connection between the first terminal device and the access network device. This further prevents the access network device from decrypting erroneous data using the new key after the first terminal device and the access network device reestablish a connection.

[0207] Specifically, when the fourth condition is met, the second terminal device releases the second configuration. The second configuration is used for the second terminal device to receive a message from the first terminal device. The fourth condition includes one of the following: the second terminal device detects a radio link failure between the second terminal device and the access network device; the second terminal device sends a first message; or the second terminal device sends a second request message. In other words, the second terminal device releases the second configuration when the second terminal device detects a radio link failure between the second terminal device and the access network device, when the second terminal device sends the first message, or when the second terminal device sends the second request message.

[0208] Exemplarily, the first configuration is allocated by the first terminal device to the second terminal device. The second configuration may include an RLC mode, an RLC sequence number, a logical channel identifier, and the like.

[0209] The following describes in detail the process of reestablishing the connection between the first terminal device and the access network device.

[0210] S303a: The first terminal device sends a first request message to the second terminal device, where the first request message is used to request re-establishment of the connection between the first terminal device and the access network device. Correspondingly, the second terminal device receives the first request message from the first terminal device.

[0211] Exemplarily, the first request message may be a radio resource control reestablishment request (RRC reestablishment request) message, and the first request is specifically used to request establishment of an RRC connection between the first terminal device and the access network device.

[0212] S303b: The second terminal device sends a first request message to the access network device. Correspondingly, the access network device receives the first request message from the second terminal device.

[0213] In some embodiments, after receiving the first request message, the second terminal device does not process the content of the first request message, but forwards the first request message carrying the SRAP header to the access network device.

[0214] S304a, the access network device sends a first response message to the second terminal device, where the first response message is a response message of the access network device to the first request message described in S303b. Accordingly, the second terminal device receives the first response message sent by the access network device.

[0215] Exemplarily, the first response message may be an RRC Reestablishment message.

[0216] Exemplarily, the first response message is further used to indicate a second key, which is used to decrypt data transmitted after the first terminal device reestablishes a connection with the access network device. In other words, the second key is a reestablished key. For example, the first response message includes a next hop chaining count (NCC) parameter, which is used to determine the second key.

[0217] In some embodiments, if the access network device accepts to re-establish a connection with the first terminal device, the access network device executes S304; if the access network device refuses to re-establish a connection with the first terminal device, the access network device does not execute S304a.

[0218] In some other embodiments, the access network device executes S304a regardless of whether the access network device accepts to re-establish the connection with the first terminal device. Here, the first response message is used to indicate whether the access network device accepts or refuses to re-establish the connection with the first terminal device.

[0219] S304b: The second terminal device sends a first response message to the first terminal device. Correspondingly, the first terminal device receives the first response message sent by the second terminal device.

[0220] In some embodiments, after receiving the first response message, the second terminal device directly forwards the first response message to the first terminal device.

[0221] In an embodiment where the access network device accepts to re-establish a connection with the first terminal device and the access network device executes S304, the first terminal device receives a first response message, and the first terminal device executes S305a. In an embodiment where the access network device executes S304a regardless of whether the access network device accepts to re-establish a connection with the first terminal device, the first terminal device receives the first response message, determines that the first response message is used to indicate that the access network device accepts to re-establish a connection with the first terminal device, and the first terminal device executes S305a.

[0222] S305a, the first terminal device sends a fourth message to the second terminal device, where the fourth message is used to indicate that the connection between the first terminal device and the access network device has been reestablished. Correspondingly, the second terminal device receives the fourth message from the first terminal device.

[0223] Exemplarily, the fourth message may be an RRC reestablishment complete (RRCReestablishmentComplete) message. When the first terminal device and the access network device successfully complete the RRC reestablishment, the first terminal device executes S305a.

[0224] S305b: The second terminal device sends a fourth message to the access network device. Correspondingly, the access network device receives the fourth message from the second terminal device.

[0225] In some embodiments, after receiving the fourth message, the second terminal device does not process the content of the fourth message and directly forwards the fourth message to the access network device.

[0226] S306a: The access network device sends a second message to the second terminal device. Correspondingly, the second terminal device receives the second message from the access network device.

[0227] Among them, the second message is used to modify the RRC connection between the first terminal device and the access network device.

[0228] Exemplarily, the second message may be an RRC reconfiguration message (RRCRecongfiguration).

[0229] Exemplarily, the second message is used to indicate one of the following: one or more added or modified PC5 relay RLC channel configurations, and one or more released PC5 relay RLC channel configurations; full configuration (fullConfig) reconfiguration indication information and one or more added or modified radio link control channel configurations; one or more added or modified radio link control channel configurations.

[0230] Exemplarily, one or more released radio link control channel configurations indicate one or more PC5 RLC channel identifiers that need to be released, and one or more added or modified radio link control channel configurations include one or more PC5 RLC channel identifiers that need to be newly added, RLC configuration and MAC configuration, wherein the RLC configuration includes the RLC mode and corresponding parameters, and the MAC configuration includes sidelink logical channel parameters.

[0231] This embodiment of the present application does not limit the form of the one or more released radio link control channel configurations indicated by the second message.

[0232] For example, the second message may indicate one or more released radio link control channel configurations in the form of a list. Here, the list may be referred to as a radio link control channel release list of the first terminal device and the second terminal device.

[0233] For another example, the second message may indicate one or more released radio link control channel configurations via a first information element. Here, the first information element may be called an sl-RLC-Channel To Release List. The first information element may include one or more RLC channel IDs. Here, the RLC channel IDs are previously configured.

[0234] This embodiment of the present application does not limit the form of the one or more added or modified radio link control channel configurations indicated by the second message.

[0235] For example, the second message may indicate one or more added or modified radio link control channel configurations in the form of a list. Here, the list may be referred to as a radio link control channel addition or modification list of the first terminal device and the second terminal device.

[0236] For another example, the second message may indicate one or more added or modified radio link control channel configurations via a second information element. Here, the second information element may be called sl-RLC-Channel To Add Mod List. The specific structure of the second information element may be one or more {RLC channel ID, configuration} configurations. Here, the RLC channel ID is not configured.

[0237] In some embodiments, when the first terminal device stops sending data to the second terminal device and the first terminal device does not release the PC5 RLC channel (including releasing the RLC entity, MAC reset, etc.), the second message is used for one of the following: one or more added or modified PC5 relay RLC channel configurations, and one or more released PC5 relay RLC channel configurations; full configuration (fullConfig) reconfiguration indication information and one or more added or modified radio link control channel configurations.

[0238] In some embodiments, when the first terminal device releases the PC5 RLC channel by itself (including releasing the RLC entity, MAC reset, etc.), this application does not limit the content carried by the second message. The content carried by the second message may depend on the implementation of the access network device, for example, the second message only carries the release configuration.

[0239] In some embodiments, when the first terminal device releases the first configuration, the second message is used to indicate one or more added or modified radio link control channel configurations.

[0240] S306b: The second terminal device sends a second message to the first terminal device. Correspondingly, the first terminal device receives the second message from the second terminal device.

[0241] In some embodiments, after receiving the second message, the second terminal device does not process the content of the second message and directly forwards the second message to the first terminal device.

[0242] S307: The first terminal device is configured according to the second message.

[0243] In a case where the second message is used to indicate: one or more added or modified radio link control channel configurations, and one or more released radio link control channel configurations, or in a case where the second message is used to indicate full configuration (fullConfig) reconfiguration indication information and one or more added or modified radio link control channels, the first terminal device releases and reestablishes the RLC channel on PC5 between the first terminal device and the second terminal device (referred to as PC5 RLC channel for short), and configures a logical channel for the MAC entity. Releasing and reestablishing the PC5 RLC channel includes releasing the RLC entity and the corresponding logical channel, and reestablishing the RLC entity.

[0244] In the case where the second message is used to indicate one or more added or modified radio link control channels, the first terminal device releases and re-establishes the PC5 RLC channel. Releasing the PC5 RLC channel includes releasing the RLC entity and the corresponding logical channel, and re-establishing the PC5 RLC channel includes re-establishing the RLC entity and the corresponding logical channel. Exemplarily, the first terminal device may process the configuration information carried in the second message according to the full configuration (fullConfig) by default, release / clear all current dedicated wireless configurations, including the PC5 RLC channel configuration, and establish a PC5 RLC channel according to the one or more PC5 relay RLC channel configurations to be added in the second message. Establishing a PC5 RLC channel includes establishing an RLC entity and configuring a logical channel for the MAC entity. It should be noted that, in this example, the one or more added or modified PC5 relay RLC channel configurations indicated by the second message include one or more PC5 relay RLC channel configurations that need to be added, and do not include one or more PC5 relay RLC channel configurations that need to be modified.

[0245] The following describes in detail the process of reestablishing the connection between the second terminal device and the access network device.

[0246] S402: The second terminal device sends a second request message to the access network device. Correspondingly, the access network device receives the second request message from the second terminal device.

[0247] Exemplarily, the second request message may be an RRC reestablishment request message, and the second request is specifically used to request establishment of an RRC connection between the second terminal device and the access network device.

[0248] S403: The access network device sends a second response message to the second terminal device, where the second response message is a response message of the access network device to the second request message in S402. Accordingly, the second terminal device receives the second response message sent by the access network device.

[0249] Exemplarily, the second response message may be an RRC Reestablishment (RRCReestablishment) message.

[0250] In some embodiments, the access network device accepts to re-establish a connection with the second terminal device, and the access network device executes S403; the access network device refuses to re-establish a connection with the first terminal device, and the access network device does not execute S403.

[0251] In some other embodiments, the access network device executes S403 regardless of whether the access network device accepts to re-establish the connection with the second terminal device. Here, the second response message is used to indicate whether the access network device accepts or refuses to re-establish the connection with the second terminal device.

[0252] S404: The second terminal device sends a fifth message to the first terminal device. Correspondingly, the first terminal device receives the fifth message sent from the second terminal device.

[0253] In an embodiment where the access network device accepts to re-establish a connection with the second terminal device and the access network device executes S403, the second terminal device receives a second response message, and the second terminal device executes S404. In an embodiment where the access network device executes S403 regardless of whether the access network device accepts to re-establish a connection with the second terminal device, the second terminal device receives the second response message, determines that the second response message is used to indicate that the access network device accepts to re-establish a connection with the second terminal device, and the second terminal device executes S404.

[0254] Exemplarily, the fifth message may be an RRCReestablishment complete message. When the second terminal device and the access network device successfully complete the RRC reestablishment, the second terminal device executes S404.

[0255] S405: The access network device sends a third message to the second terminal device. Correspondingly, the second terminal device receives the third message from the access network device.

[0256] Among them, the third message is used to indicate the configuration information of the communication between the second terminal device and the access network device.

[0257] Exemplarily, the third message may be an RRC Recongfiguration message.

[0258] Exemplarily, the third message is used to indicate one of the following: one or more added or modified radio link control channel configurations, and one or more released radio link control channel configurations; full configuration (fullConfig) reconfiguration indication information and one or more added or modified radio link control channel configurations; or one or more added or modified radio link control channel configurations. For a detailed description of the content indicated by the third message, please refer to the above description and will not be repeated here.

[0259] This embodiment of the present application does not limit the form of the one or more released radio link control channel configurations indicated by the third message.

[0260] For example, the third message may indicate one or more released radio link control channel configurations in the form of a list. Here, the list may be referred to as a radio link control channel release list of the first terminal device and the second terminal device.

[0261] For another example, the third message may indicate one or more released radio link control channel configurations via a third information element. Here, the third information element may be called an sl-RLC-Channel To Release List. The specific structure of the third information element may be one or more RLC channel IDs. Here, the RLC channel IDs are previously configured.

[0262] This embodiment of the present application does not limit the form of the one or more added or modified radio link control channel configurations indicated by the third message.

[0263] For example, the third message may indicate one or more added or modified radio link control channel configurations in the form of a list. Here, the list may be referred to as a radio link control channel addition list of the first terminal device and the second terminal device.

[0264] For another example, the third message may indicate one or more added or modified radio link control channel configurations via a fourth information element. Here, the fourth information element may be called sl-RLC-Channel To Add Mod List. The specific structure of the second fourth information element may be one or more {RLC channel ID, configuration} configurations. Here, the RLC channel ID is not configured.

[0265] In some embodiments, when the second terminal device stops sending data to the first terminal device and the first terminal device does not release the PC5 RLC channel (including releasing the RLC entity, MAC reset, etc.), the third message is used for one of the following: one or more added or modified PC5 relay RLC channel configurations, and one or more released PC5 relay RLC channel configurations; full configuration (fullConfig) reconfiguration indication information and one or more added or modified radio link control channel configurations.

[0266] In some embodiments, when the second terminal device releases the PC5 RLC channel by itself (including releasing the RLC entity, MAC reset, etc.), this application does not limit the content carried by the third message. The content carried by the third message may depend on the implementation of the access network device, for example, the third message only carries the release configuration.

[0267] In some embodiments, when the second terminal device releases the first configuration, the third message is used to indicate one or more added or modified radio link control channel configurations.

[0268] S406: The second terminal device is configured according to the third message.

[0269] When the third message is used to indicate: one or more added or modified radio link control channel configurations, and one or more released radio link control channel configurations, or when the third message is used to indicate full configuration (fullConfig) reconfiguration indication information and one or more added or modified radio link control channels, the second terminal device releases and re-establishes the PC5 RLC channel between the first terminal device and the second terminal device, and configures a logical channel for the MAC entity. Releasing and re-establishing the PC5 RLC channel includes releasing the RLC entity and the corresponding logical channel, and re-establishing the RLC entity.

[0270] In the case where the third message is used to indicate one or more added or modified radio link control channels, the second terminal device releases and re-establishes the PC5 RLC channel. Releasing the PC5 RLC channel includes releasing the RLC entity and the corresponding logical channel, and re-establishing the PC5 RLC channel includes re-establishing the RLC entity and the corresponding logical channel. Exemplarily, the second terminal device may process the configuration information carried in the third message according to the full configuration (fullConfig) by default, release / clear all current dedicated wireless configurations, including the PC5 RLC channel configuration, and establish a PC5 RLC channel according to the one or more PC5 relay RLC channel configurations to be added in the third message. Establishing a PC5 RLC channel includes establishing an RLC entity and configuring a logical channel for the MAC entity. It should be noted that, in this example, the one or more added or modified PC5 relay RLC channel configurations indicated by the third message include one or more PC5 relay RLC channel configurations that need to be added, and do not include one or more PC5 relay RLC channel configurations that need to be modified.

[0271] In this way, the second terminal device clears the downlink data cached on the second terminal device side.

[0272] FIG5 is a schematic flowchart of another communication method 500 provided in an embodiment of the present application.

[0273] As shown in Figure 5, the communication method 500 includes S501a, S501b, S502 and S503. S501a, S501b, S502 and S503 are described in detail below.

[0274] S501a: The access network device sends a first response message to the second terminal device. Correspondingly, the second terminal device receives the first response message from the access network device.

[0275] The first response message is used to indicate the second identifier and the second key.

[0276] The second key can be understood as the key used by the access network device to communicate with the first terminal device after the first terminal device and the access network device re-establish a connection. The second key is used to decrypt data transmitted after the first terminal device and the access network device re-establish a connection. For example, the first response message includes a next hop chaining count (NCC) parameter, and the first terminal device determines the second key based on the NCC parameter.

[0277] The second identifier can be understood as: a local identifier after re-establishment allocated by the access network device to the first terminal device during the process of re-establishing a connection between the access network device and the first terminal device.

[0278] Exemplarily, the first response message may be an RRC Reestablishment (RRCReestablishment) message.

[0279] S501b: The second terminal device sends a first response message to the first terminal device. Correspondingly, the first terminal device receives the first response message from the second terminal device.

[0280] In some embodiments, after receiving the first response message, the second terminal device does not process the content of the first response message, but forwards the first response message carrying the SRAP header to the first terminal device.

[0281] After receiving the first response message, the first terminal device maintains two local identifiers according to the first response message, that is, the first terminal device maintains the first identifier and the second identifier. The first terminal device maintains two keys according to the second response message, that is, the first terminal device maintains the first key and the second key.

[0282] It should be understood that, since the first response message includes the second identifier and the second key, the first terminal device assumes that there is an association between the second identifier and the second key.

[0283] S501b: The second terminal device sends the first information to the first terminal device. Correspondingly, the first terminal device receives the first information from the second terminal device.

[0284] The first information includes first data and a first identifier, the first data is encrypted using a first key, the first identifier is an identifier of the first terminal device, and the first identifier is used for the sidelink relay adaptation layer.

[0285] Here, the first key can be understood as: the key used by the access network device to communicate with the first terminal device before the first terminal device initiates re-establishment.

[0286] The first identifier can be understood as: a local identifier allocated by the access network device to the first terminal device before the first terminal device initiates re-establishment.

[0287] S503: The first terminal device processes the first data using the first key.

[0288] The first key is configured by the access network device for the first terminal device before S501 and notified to the first terminal device. In addition, the first key is associated with the first identifier.

[0289] In one example, S503 includes: decrypting the first data or discarding the first data based on the first identifier. In other words, the first terminal device first obtains the first identifier based on the first information described in S501. The first terminal device then knows that the first data is encrypted using the first key and can directly decrypt the first data or discard the first data.

[0290] In another example, S503 includes: determining, based on the first identifier, that the first data is encrypted using the first key; and decrypting the first data or discarding the first data. In other words, first, the first terminal device obtains the first identifier based on the first information described in S501. Next, the first terminal device determines, based on the first identifier, that the key used to encrypt the first data is the first key. Finally, the first terminal device directly decrypts the first data or discards the first data based on the first key.

[0291] Through communication method 500, the first terminal device maintains local identifiers of two first terminal devices. After the first terminal device receives the first information carrying the first data, it processes the first data according to the first identifier in the first information using the first key associated with the first identifier. In this way, the first terminal device can avoid decrypting the wrong data packet.

[0292] FIG6 is a schematic flowchart of another communication method 600 provided in an embodiment of the present application.

[0293] Optionally, in some embodiments, as shown in FIG6 , in addition to S501 to S503, communication method 600 may further include S301, S302, S303a, S303b, S305a, S305b, S504, S401, and S405. S501b is executed before S502, S504 is executed after S305a, and S301, S302, and S401 are optional steps. S504, S505, S506a, and S506b of communication method 600 are described in detail below. For other steps, reference may be made to the above description and will not be repeated here.

[0294] S504: The first terminal device releases the first identifier.

[0295] In some embodiments, when the first terminal device sends the fourth message to the second terminal device, the first terminal device releases the first identifier. In other embodiments, when the first terminal device does not receive the second message carrying the first identifier within a preset time, the first terminal device releases the first identifier.

[0296] The embodiment of the present application does not limit the specific value of the preset time. For example, the preset time may be a factory default value of the first terminal device, or the preset time may be configured by the core network, or the preset time may be determined by the first terminal device based on implementation.

[0297] After the first terminal device and the access network device complete the re-establishment, the first terminal device releases the first identifier and stops maintaining the first identifier, thereby reducing the overhead of the first terminal device.

[0298] FIG7 is a schematic flowchart of another communication method 700 provided in an embodiment of the present application.

[0299] As shown in FIG7 , communication method 700 includes S701a, S702 to S704, with S703 executed after S701a. This embodiment of the application does not limit the order in which S702 and S701a are executed, or whether they are executed simultaneously. Furthermore, this embodiment does not limit the order in which S702 and S701a are executed, or whether they are executed simultaneously. S701a, S702 to S704 are described in detail below.

[0300] S701a: The first terminal device sends a first request message to the second terminal device, where the first request message is used to request to re-establish a connection between the first terminal device and the access network device. Correspondingly, the second terminal device receives the first request message from the first terminal device.

[0301] For the description of 701a, please refer to the description of S303a above, which will not be repeated here.

[0302] S702, reestablishing a third entity, where the third entity is used by the first terminal device to send a message to the second terminal device.

[0303] Exemplarily, the third entity may be a SRAP entity.

[0304] S703: The second terminal device sends the first information to the first terminal device. Correspondingly, the first terminal device receives the first information from the second terminal device.

[0305] For the description of S703 , please refer to the description of S501 b above, which will not be repeated here.

[0306] S704: The first terminal device stops processing the first data.

[0307] In one example, the first terminal device stopping processing the first data can be understood as the first terminal device caching the first data, or the first terminal device temporarily storing the first data, or the protocol entity of the first terminal device stopping submitting the first data to the upper layer entity.

[0308] In some embodiments, the first terminal device includes a third entity and a fourth entity, the fourth entity is a wireless link control entity, and stopping processing the first data includes: the fourth entity stops submitting the first data to the third entity, or the fourth entity discards the first data.

[0309] Optionally, in some embodiments, before the fourth entity stops delivering the first data to the third entity, the third entity may instruct the fourth entity to stop delivering the first data to the third entity.

[0310] Optionally, in some embodiments, before S704, the first terminal device has not received the corresponding SRAP configuration of the access network device or the re-established local identifier of the first terminal device, such as the second identifier.

[0311] Through method 700, after the first terminal device sends a request to the access network device through the second terminal device to reestablish the connection between the first terminal device and the access network device, the first terminal device reestablishes the third entity. However, because the first terminal device has not reestablished the configuration corresponding to the third entity or has not received an instruction from the access network device to establish the configuration corresponding to the third entity, the first terminal device stops processing the first data after receiving the first information, thereby preventing the first terminal device from decoding an erroneous data packet.

[0312] FIG8 is a schematic flowchart of another communication method 800 provided in an embodiment of the present application.

[0313] Optionally, in some embodiments, as shown in FIG8 , in addition to S701a and S702 to S704, communication method 800 may further include S301, S302, S501a, S501b, S305a, S305b, S401 to S405, and S705 to S708. S501b is executed after S703, S705 to S708 are executed after S402, and S706 is executed before S403. S301, S302, and S401 are optional steps. S705 to S708 are described below. For other steps, refer to the above description and are not repeated here.

[0314] S705, the second terminal device reestablishes the fifth entity, and the fifth entity is used by the second terminal device to forward messages transmitted between the first terminal device and the access network device.

[0315] Exemplarily, the fifth entity may be a SRAP entity.

[0316] S706: The first terminal device sends third information to the second terminal device, where the third information includes the second data and the first identifier, and the second data is encrypted using the first key. Correspondingly, the second terminal device receives the third information from the first terminal device.

[0317] For the first identifier, please refer to the relevant description in S501b above, which will not be repeated here.

[0318] S707: The second terminal device stops processing the second data.

[0319] In one example, the second terminal device stopping processing the second data can be understood as the second terminal device caching the second data, or the second terminal device temporarily storing the second data, or the protocol entity of the second terminal device stopping submitting the second data to the upper layer entity.

[0320] In some embodiments, the first terminal device includes a fifth entity and a sixth entity, the fifth entity is a radio link control entity, and stopping processing the first data includes: the sixth entity stops submitting the second data to the fifth entity, or the fifth entity discards the second data.

[0321] Optionally, in some embodiments, before the sixth entity stops delivering the second data to the fifth entity, the fifth entity may instruct the sixth entity to stop delivering the second data to the fifth entity.

[0322] Optionally, in some embodiments, before S707, the second terminal device has not received the corresponding SRAP configuration of the access network device or the re-established local identifier of the first terminal device, such as the second identifier.

[0323] It should be noted that, in some embodiments, S401, S705 to S708 can be implemented independently of the communication method 800. In this embodiment, S401 and S708 are optional steps. In this embodiment, after the second terminal device sends a request to the access network device to re-establish the connection between the second terminal device and the access network device, the second terminal device re-establishes the fifth entity by itself. However, since the second terminal device has not re-established the configuration corresponding to the fifth entity or the second terminal device has not received the instruction from the access network device to establish the configuration corresponding to the fifth entity, the second terminal device stops processing the second data after receiving the third information. Furthermore, after the second terminal device and the access network device are re-established, the access network device will not receive the data packet encrypted with the first key forwarded by the second terminal device, so that the access network device will not decrypt erroneous data.

[0324] FIG9 is a schematic flowchart of another communication method 900 provided in an embodiment of the present application.

[0325] As shown in Figure 9, the communication method 900 includes S901a, S902, S903 and S904, which are executed in sequence. S901a, S902, S903a and S904 are described in detail below.

[0326] S901a, the access network device sends a sixth message to the second terminal device, where the sixth message is used to indicate the second identifier and the second key.

[0327] Exemplarily, the sixth message may be an RRC Recongfiguration message.

[0328] For the description of the second identifier, please refer to the description of S501a above, and for the description of the second key, please refer to the description of S405 above, which will not be repeated here.

[0329] S902: The first terminal device sends third information to the second terminal device, where the third information includes the second data and the first identifier. Correspondingly, the second terminal device receives the third information from the first terminal device.

[0330] The second data is encrypted using the first key.

[0331] S903: The second terminal device forwards the third information to the access network device according to the first identifier and the second identifier. Correspondingly, the access network device receives the third information from the second terminal device.

[0332] The first identifier is configured by the access network device for the first terminal device before S901a and notified to the first terminal device.

[0333] S904: The access network device processes the second data using the first key.

[0334] In one example, S904 includes: decrypting the second data or discarding the second data based on the first identifier. In other words, the access network device first obtains the first identifier based on the third information. Then, the access network device knows that the second data is encrypted using the first key and directly decrypts the second data or discards the second data.

[0335] In another example, S904 includes: determining, based on the first identifier, that the second data is encrypted using the first key; and decrypting the second data or discarding the second data. In other words, first, the access network device obtains the first identifier based on the third information. Next, based on the first identifier, the access network device determines that the first key is used to encrypt the second data. Finally, based on the first key, the access network device directly decrypts the second data or discards the second data.

[0336] In method 900, the access network device maintains local identifiers of two first terminal devices. After the access network device receives the third information carrying the second data, it processes the second data based on the first identifier in the third information using the first key associated with the first identifier. In this way, the access network device can avoid decoding erroneous data packets.

[0337] FIG10 is a schematic flowchart of another communication method 1000 provided in an embodiment of the present application.

[0338] Optionally, in some embodiments, as shown in FIG10 , in addition to S901a, S902, S903, and S904, communication method 1000 may further include S301, S302, S303a, S303b, S501a, S501b, S305a, S305b, S504, S401 to S404, and S905. S901a, S902, S903, and S904 are performed after S401, and S301, S302, S401, S504, and S905 are optional steps. S905 of communication method 1000 is described in detail below. For other steps, reference may be made to the above description and will not be repeated here.

[0339] S905: The second terminal device releases the first identifier.

[0340] In some embodiments, after the second terminal device forwards the third information to the access network device, the second terminal device releases the first identifier. After the second terminal device forwards the third information to the access network device, the second terminal device releases the first identifier and stops maintaining the first identifier, thereby reducing the second terminal device's overhead.

[0341] In other embodiments, if the second terminal device does not receive the fourth message carrying the first identifier within a preset time, the second terminal device releases the first identifier. After the second terminal device forwards the third message to the access network device, if the second terminal device does not receive the fourth message carrying the first identifier within a preset time, the second terminal device automatically releases the first identifier and automatically stops maintaining the first identifier, thereby reducing the second terminal device's overhead.

[0342] The embodiment of the present application does not limit the specific value of the preset time. For example, the preset time may be a factory default value of the second terminal device, or the preset time may be configured by the core network, or the preset time may be determined by the second terminal device based on implementation.

[0343] It should be noted that when the access network device includes a CU and a DU, the actions of the access network device sending and receiving messages from the second terminal device in Figures 3 to 10 are performed by the DU. When the DU receives a message from the second terminal device and forwards it to the CU, the CU performs processing actions based on the content of the message. When the DU sends a message to the second terminal device, the CU first generates the message and forwards it to the DU, which then forwards it to the second terminal device. In addition, the CU can also be used to perform message or data processing actions.

[0344] For example, in S402 described above, the second terminal device sending the second request message to the access network device specifically includes the second terminal device sending the second request message to the DU of the access network device. The access network device receiving the second request message from the second terminal device includes the DU of the access network device receiving the second request message from the second terminal device. The specific processes of S404, S303b, S305b, S306b, S306b, and S903 described above are similar to the specific process of S402 and will not be repeated here.

[0345] For another example, in S403 described above, the access network device sends a second response message to the second terminal device, specifically including: the CU of the access network device generates a second response message, sends the second response message to the DU of the access network device, and the DU of the access network device forwards the second response message to the second terminal device. The second terminal device receives the second response message sent from the access network device, specifically including the second terminal device receives the second response message sent from the DU of the access network device. The specific processes of S405, S304a, S306a, S501a, and S901a described above are similar to the specific process of S403 and will not be repeated here.

[0346] For example, in S904 described above, the access network device using the first key to process the second data specifically includes: the CU using the first key to process the second data.

[0347] After the first terminal device and the second terminal device trigger the re-establishment, before the first terminal device sends a re-establishment request message to the second terminal device, there will be a misalignment in the RLC serial numbers (serial number, SN) of the first terminal device and the second terminal device. In this way, the second terminal device cannot correctly receive the re-establishment request message and the re-establishment completion message of the first terminal device.

[0348] In view of this, an embodiment of the present application further provides a communication method 1100 as shown in FIG11 . The communication method 1100 is described in detail below in conjunction with FIG11 .

[0349] FIG11 is a schematic flowchart of another communication method 1100 provided in an embodiment of the present application.

[0350] As shown in Figure 11, the communication method 1100 includes S1101 to S1103. S1101 to S1103 are described in detail below.

[0351] S1101, the second terminal device initiates re-establishment between the second terminal device and the access network device.

[0352] In one example, when the second terminal device detects that an RLF occurs on the Uu interface between the second terminal device and the access network device, the second terminal device executes S1101. In another example, when the second terminal device sends a first message to the first terminal device, the second terminal device executes S1101. For details about the first message, refer to the description of S301 above and will not be repeated here.

[0353] It should be understood that the second terminal device initiating the re-establishment between the second terminal device and the access network device can be understood as the second terminal device initiating the re-establishment process between the second terminal device and the access network device.

[0354] S1102: Release the first entity and the second entity.

[0355] Exemplarily, the first entity and the second entity are RLC entities.

[0356] The first entity is used to receive or send a message carried by the first signaling radio bearer of the first terminal device (referred to as the first signaling radio bearer message), and the second entity is used to receive or send a message carried by the second signaling radio bearer of the first terminal device (referred to as the second signaling radio bearer message). The first signaling radio bearer is used to carry the first request message, and the second signaling radio bearer is used to carry the fourth message. The first request message is used to request the re-establishment of the connection between the first terminal device and the access network device, and the fourth message is used to indicate that the connection between the first terminal device and the access network device has been re-established. In this way, the first entity is used for the second terminal device to receive the first request message from the first terminal device or to send the first request message of the first terminal device to the access network device, and the second entity is used for the second terminal device to receive the fourth message from the first terminal device or to send the fourth message of the first terminal device to the access network device.

[0357] For example, the first signaling radio bearer is SRB0 of the first terminal device, and the first entity is an RLC entity for receiving or sending SRB0 messages of the first terminal device. The second radio bearer is SRB1 of the first terminal device, and the second entity is an RLC entity for receiving or sending SRB1 messages of the first terminal device.

[0358] S1103: Apply the first predefined configuration to the third entity, and apply the second predefined configuration to the fourth entity.

[0359] The third entity is used for the second terminal device to receive the first request message from the first terminal device, and the fourth entity is used for the second terminal device to receive the fourth message from the first terminal device.

[0360] Exemplarily, the third entity and the fourth entity are RLC entities.

[0361] Applying the first predefined configuration to the third entity can be understood as reestablishing the RLC entity corresponding to SL-RLC0. The PC5 relay RLC channel to which the first predefined configuration is applied is called SL-RLC0.

[0362] In one example, applying the first predefined configuration to the third entity includes establishing a fifth entity and applying the specified configuration of SL-RLC0 to obtain the third entity. In another example, applying the first predefined configuration to the third entity includes establishing the fifth entity according to the specified configuration of SL-RLC0 to obtain the fourth entity.

[0363] Applying the second predefined configuration to the fourth entity can be understood as reestablishing the RLC entity corresponding to SL-RLC1. The PC5 relay RLC channel to which the second predefined configuration is applied is called SL-RLC1.

[0364] In one example, applying the second predefined configuration to the fourth entity includes establishing a sixth entity and applying the default configuration of SL-RLC1. In another example, applying the second predefined configuration to the fourth entity includes establishing the fourth entity according to the default configuration of SL-RLC1.

[0365] Optionally, in some embodiments, when the first terminal device receives the first message from the second terminal device, the first terminal device releases the RLC entity corresponding to the first radio bearer and the RLC entity corresponding to the second radio bearer, and re-establishes the RLC entities corresponding to SL-RLC0 and SL-RLC1, and then initiates a triggering RRC re-establishment process.

[0366] Through method 1100, after the second terminal device initiates the re-establishment process between the second terminal device and the access network device, the second terminal device releases the PC5 RLC entity of the second terminal device corresponding to the message carried by the first signaling radio bearer for receiving or sending the first terminal device and the PC5 RLC entity corresponding to the message carried by the second signaling radio bearer for receiving or sending the first terminal device, and re-establishes the RLC entity for receiving or sending the message carried by the first signaling radio bearer for receiving or sending the first terminal device and the RLC entity for receiving or sending the message carried by the second signaling radio bearer for receiving or sending the first terminal device. In this way, the first terminal device sends the first request message and the fourth message to the access network device through the second terminal device. The RLC SNs of the first terminal device and the second terminal device both start from 0. Therefore, the second terminal device can correctly receive the first request message and the fourth message, and then forward them to the access network device, ensuring that the RRC re-establishment process of the first terminal device proceeds normally.

[0367] It should be noted that the communication method 300 shown in Figure 3 and the communication method shown in any one of Figures 5 to 10 can be implemented in combination or separately, and this embodiment of the present application does not limit this. The communication method 400 shown in Figure 4 and the communication method shown in any one of Figures 5 to 10 can be implemented in combination or separately, and this embodiment of the present application does not limit this. The communication method shown in any one of Figures 3 to 10 and the communication method 1100 shown in Figure 11 can be implemented in combination or separately, and this embodiment of the present application does not limit this. In addition, the communication method 1100 is also applicable to O-RAN systems.

[0368] The communication method provided by the embodiment of the present application is described in detail above with reference to Figures 3 to 11. The apparatus provided by the embodiment of the present application is described in detail below with reference to Figures 12 and 13.

[0369] Figure 12 is a schematic block diagram of an example communication device provided in an embodiment of the present application. As shown in Figure 12, the communication device 1200 includes a transceiver unit 1210 and a processing unit 1220. The transceiver unit 1210 can implement corresponding communication functions, and the processing unit 1220 is used to perform data processing to enable the communication device to implement the aforementioned method embodiment. The transceiver unit 1210 can also be referred to as a communication interface or a communication unit.

[0370] Optionally, the communication device 1200 may further include a storage unit, which may be used to store instructions and / or data. The processing unit 1220 may read the instructions and / or data in the storage unit so that the communication device implements the aforementioned method embodiment.

[0371] The communication device 1200 can be used to execute the actions performed by the first terminal device in the above method embodiment. In this case, the communication device 1200 can be the first terminal device, or a component that can be configured on the first terminal device. The transceiver unit 1210 is used to execute the transceiver-related operations on the first terminal device side in the above method embodiment. The storage unit is used to execute the data or instruction storage-related operations on the first terminal device side in the above method embodiment. The processing unit 1220 is used to execute the processing-related operations on the first terminal device side in the above method embodiment.

[0372] Alternatively, the communication device 1200 can be used to execute the actions performed by the second terminal device in the above method embodiment. In this case, the communication device 1200 can be a second terminal device, or a component that can be configured on the second terminal device. The transceiver unit 1210 is used to execute the transceiver-related operations on the second terminal device side in the above method embodiment, the storage unit is used to execute the data or instruction storage-related operations on the second terminal device side in the above method embodiment, and the processing unit 1220 is used to execute the processing-related operations on the second terminal device side in the above method embodiment.

[0373] Alternatively, the communication device 1200 can be used to execute the actions performed by the access network device in the above method embodiment. In this case, the communication device 1200 can be an access network device, or a component that can be configured on the access network device. The transceiver unit 1210 is used to execute the transceiver-related operations on the access network device side in the above method embodiment. The storage unit is used to execute the data or instruction storage-related operations on the access network device side in the above method embodiment. The processing unit 1220 is used to execute the processing-related operations on the access network device side in the above method embodiment.

[0374] It should be understood that the specific process of each unit executing the above corresponding steps has been described in detail in the above method embodiment, and for the sake of brevity, it will not be repeated here.

[0375] The processing unit 1220 in the above embodiment can be implemented by at least one processor or processor-related circuits. The transceiver unit 1210 can be implemented by a transceiver or transceiver-related circuits. The transceiver unit 1210 can also be referred to as a communication unit or communication interface. The storage unit can be implemented by at least one memory.

[0376] Figure 13 is a schematic block diagram of another example communication device 1300 provided in an embodiment of the present application. As shown in the figure, the device 1300 includes: at least one processor 1310 and a transceiver 1320. The processor 1310 is coupled to a memory and is configured to execute instructions stored in the memory to send and / or receive signals. Optionally, the device 1300 also includes a memory 1330 for storing instructions. Optionally, the device 1300 also includes a transceiver 1320, and the processor 1310 controls the transceiver 1320 to send and / or receive signals.

[0377] It should be understood that the processor 1310 and memory 1330 may be combined into a processing device, and the processor 1310 is used to execute the program code stored in the memory 1330 to implement the above functions. In specific implementations, the memory 1330 may also be integrated into the processor 1310 or independent of the processor 1310.

[0378] It should also be understood that the transceiver 1320 may include a transceiver (or receiver) and a transmitter (or transmitter). The transceiver may further include an antenna, and the number of antennas may be one or more. The transceiver 1320 may also be a communication interface or interface circuit.

[0379] For example, the transceiver 1320 in the apparatus 1300 may correspond to the transceiver unit in the above-mentioned embodiment, and the processor 1310 in the apparatus 1300 may correspond to the processing unit in the above-mentioned embodiment. It should be understood that the specific process of each transceiver and processor executing the above-mentioned corresponding steps has been described in detail in the above-mentioned method embodiment, and for the sake of brevity, it will not be repeated here.

[0380] 14 is a schematic block diagram of a chip system 1400 according to an embodiment of the present application. The chip system 1400 (or also referred to as a processing system) includes a logic circuit 1410 and an input / output interface 1420 .

[0381] Logic circuit 1410 may be a processing circuit within chip system 1400. Logic circuit 1410 may be coupled to a storage unit and invoke instructions within the storage unit, enabling chip system 1400 to implement the methods and functions of various embodiments of the present application. Input / output interface 1420 may be an input / output circuit within chip system 1400, outputting information processed by chip system 1400 or inputting data or signaling information to be processed into chip system 1400 for processing.

[0382] As a solution, the chip system 1400 is used to implement the operations performed by the first terminal device in each of the above method embodiments.

[0383] For example, the logic circuit 1410 is used to implement the processing-related operations performed by the terminal device in the above method embodiment; the input / output interface 1420 is used to implement the sending and / or receiving-related operations performed by the first terminal device in the above method embodiment.

[0384] As another solution, the chip system 1400 is used to implement the operations performed by the second terminal device in the above method embodiments.

[0385] For example, the logic circuit 1410 is used to implement the processing-related operations performed by the second terminal device in the above method embodiment; the input / output interface 1420 is used to implement the sending and / or receiving-related operations performed by the second terminal device in the above method embodiment.

[0386] As another solution, the chip system 1400 is used to implement the operations performed by the access network device in the above various method embodiments.

[0387] For example, the logic circuit 1410 is used to implement the processing-related operations performed by the access network device in the above method embodiment; the input / output interface 1420 is used to implement the sending and / or receiving-related operations performed by the access network device in the above method embodiment.

[0388] An embodiment of the present application also provides a computer-readable storage medium on which computer instructions are stored for implementing the methods executed by a communication device (such as a first terminal device, a second terminal device, or an access network device) in the above-mentioned method embodiments.

[0389] An embodiment of the present application also provides a computer program product comprising instructions, which, when executed by a computer, implement the methods performed by a communication device (such as a first terminal device, a second terminal device, or an access network device) in the above-mentioned method embodiments.

[0390] An embodiment of the present application also provides a communication system, which includes the first terminal device, the second terminal device and the access network device in the above embodiments.

[0391] The explanation of the relevant contents and beneficial effects of any of the above-mentioned devices can be referred to the corresponding method embodiments provided above, which will not be repeated here.

[0392] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the above-mentioned units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0393] The units described above as separate components may or may not be physically separate, and 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 these units may be selected according to actual needs to implement the solutions provided in this application.

[0394] In addition, each functional unit in each embodiment of the present application may be integrated into one unit, each unit may exist physically separately, or two or more units may be integrated into one unit.

[0395] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0396] When software is used for implementation, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. For example, the computer can be a personal computer, a server, or a network device, etc. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, server or data center to another website, computer, server or data center by wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.). About computer-readable storage media, reference can be made to the above description.

[0397] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: The communication method is applied to a first terminal device, the first terminal device communicates with an access network device through a second terminal device, and the communication method includes: receiving a first message from the second terminal device, where the first message is used to indicate that a wireless link failure occurs between the second terminal device and the access network device; Stop sending data to the second terminal device, where the data includes data sent by the first terminal device to the access network device through the second terminal device.

2. The communication method according to claim 1, characterized in that: The method further comprises: A first request message is sent to the second terminal device, where the first request message is used to request to re-establish a connection between the first terminal device and the access network device.

3. The communication method according to claim 1 or 2, characterized in that: The method further comprises: When the first condition is met, releasing the first entity; The first entity is used by the first terminal device to send a message to the second terminal device; The first condition includes that the first terminal device receives the first message or the first terminal device sends a first request message.

4. The communication method according to any one of claims 1 to 3, characterized in that: The communication method further comprises: When the second condition is met, releasing the first configuration; Wherein, the first configuration is used for the first terminal device to receive a message from the second terminal device; The second condition includes that the first terminal device receives the first message or the first terminal device sends a first request message.

5. The communication method according to any one of claims 1 to 4, characterized in that: The communication method further comprises: receiving a second message from the access network device, the second message being used to indicate one or more added or modified radio link control channel configurations; Release the radio link control channel configuration between the first terminal device and the second terminal device.

6. A communication method, characterized in that: The communication method is applied to a second terminal device, the second terminal device is used to provide a relay service for communication between the first terminal device and the access network device, and the communication method includes: Sending a first message to the first terminal device, where the first message is used to indicate that a wireless link failure occurs between the second terminal device and the access network device; Stop sending data to the first terminal device, where the data includes data sent by the access network device to the first terminal device through the second terminal device.

7. The communication method according to claim 6, characterized in that: The communication method further comprises: A second request message is sent to the access network device, where the second request message is used to request to re-establish a connection between the second terminal device and the access network device.

8. The communication method according to claim 6 or 7, characterized in that: The communication method further comprises: When the third condition is met, releasing the second entity; The second entity is used by the second terminal device to send a message to the first terminal device; The third condition includes one of the following: the second terminal device detects that a wireless link failure occurs between the second terminal device and the access network device; the second terminal device sends the first message; the second terminal device sends a second request message.

9. The communication method according to any one of claims 6 to 8, characterized in that: The communication method further comprises: When the fourth condition is met, releasing the second configuration; The second configuration is used for the second terminal device to receive a message from the first terminal device; The fourth condition includes one of the following: the second terminal device detects that a wireless link failure occurs between the second terminal device and the access network device; the second terminal device sends the first message; the second terminal device sends a second request message.

10. The communication method according to any one of claims 6 to 9, characterized in that: The communication method further comprises: receiving a third message from the access network device, the third message being used to indicate one or more added or modified radio link control channel configurations; Release the radio link control channel configuration between the first terminal device and the second terminal device.

11. A communication method, characterized in that: The communication method is applied to a first terminal device, the first terminal device communicates with an access network device through a second terminal device, and the communication method includes: Receiving a first response message from the access network device, where the first response message is used to indicate a second identifier and a second key; Receive first information from a second terminal device, where the first information includes first data and a first identifier, where the first data is encrypted using a first key, where the first identifier is an identifier of the first terminal device, and where the first identifier is used for a sidelink relay adaptation layer; The first data is processed using the first key.

12. The communication method according to claim 11, characterized in that: The using the first key to process the first data comprises: The first data is decrypted or discarded according to the first identifier.

13. The communication method according to claim 12, characterized in that: The decrypting the first data or discarding the first data according to the first identifier includes: Determining, according to the first identifier, that the first data is encrypted using the first key; The first data is decrypted or discarded.

14. The communication method according to any one of claims 11 to 13, characterized in that: The communication method further comprises: Stop sending data to the second terminal device, where the data includes data sent by the first terminal device to the access network device through the second terminal device.

15. The communication method according to any one of claims 11 to 14, characterized in that: The communication method further comprises: Sending a fourth message to the access network device, where the fourth message is used to indicate that the connection between the first terminal device and the access network device has been reestablished; Release the first identifier.

16. The communication method according to claim 15, characterized in that: The releasing the first local identifier comprises: If the second information carrying the first identifier is not received within a preset time, the first identifier is released.

17. A communication method, characterized in that: The communication method is applied to a first terminal device, the first terminal device communicates with an access network device through a second terminal device, and the communication method includes: Sending a first request message to the second terminal device, where the first request message is used to request to re-establish a connection between the first terminal device and the access network device; Rebuilding a third entity, where the third entity is used by the first terminal device to send a message to the second terminal device; Receive first information from the second terminal device, where the first information includes first data and a first identifier, where the first data is encrypted using a first key, where the first identifier is an identifier of the first terminal device, and where the first identifier is used for a sidelink relay adaptation layer; Stop processing the first data.

18. The communication method according to claim 17, characterized in that: The first terminal device includes the third entity and the fourth entity, the fourth entity is a radio link control entity, and the stopping of processing the first data includes: The fourth entity stops submitting the first data to the third entity, or the fourth entity discards the first data.

19. The communication method according to claim 17 or 18, characterized in that: The communication method further comprises: Stop sending data to the second terminal device, where the data includes data sent by the first terminal device to the access network device through the second terminal device.

20. A communication method, characterized in that: The communication method is applied to a second terminal device, the second terminal device is used to provide a relay service for communication between the first terminal device and the access network device, and the communication method includes: Sending a second request message to the access network device, where the second request message is used to request to re-establish a connection between the second terminal device and the access network device; Reconstructing a fifth entity, where the fifth entity is used for the second terminal device to forward a message transmitted between the first terminal device and the access network device; Receive third information from the first terminal device, the third information including second data and a first identifier, the second data is encrypted using a first key, the first identifier is an identifier of the first terminal device, and the first identifier is used for a sidelink relay adaptation layer; Stop processing the second data.

21. The communication method according to claim 20, characterized in that: The second terminal device includes the fifth entity and the sixth entity, the sixth entity is a radio link control entity, and the stopping of processing the second data includes: The sixth entity stops submitting the second data to the fifth entity, or the sixth entity discards the second data.

22. The communication method according to claim 20 or 21, characterized in that: The communication method further comprises: Stop sending data to the first terminal device, the data including the data sent by the access network device to the first terminal device through the second terminal device Data sent by a terminal device.

23. A communication method, characterized in that: The communication method is applied to an access network device, and the communication method includes: Sending a sixth message to the second terminal device, where the sixth message is used to indicate the second identifier and the second key; receiving third information from a second terminal device, the third information including second data and a first identifier, the second data being encrypted using a first key, the second terminal device being used to provide a relay service for communication between the first terminal device and the access network device; Processing the second data using the first key; The first identifier and the second identifier are identifiers of the first terminal device, and the first identifier and the second identifier are used for the sidelink relay adaptation layer.

24. The communication method according to claim 23, characterized in that: The using the first key to process the second data comprises: According to the first identifier, the second data is decrypted or discarded.

25. The communication method according to claim 24, characterized in that: The decrypting the second data or discarding the second data according to the first identifier includes: determining, according to the first identifier, that the second data is encrypted using the first key; The second data is decrypted or discarded.

26. A communication method, characterized in that: The communication method is applied to a second terminal device, the second terminal device is used to provide a relay service for communication between the first terminal device and the access network device, and the communication method includes: Initiate re-establishment between the second terminal device and the access network device; releasing the first entity and the second entity; applying the first predefined configuration to the third entity; applying the second predefined configuration to the fourth entity; Among them, the first entity and the third entity are used for the second terminal device to receive a first request message from the first terminal device, the second entity and the fourth entity are used for the second terminal device to receive a fourth message from the first terminal device, the first request message is used to request to re-establish the connection between the first terminal device and the access network device, and the fourth message is used to indicate that the connection between the first terminal device and the access network device has been re-established.

27. A communication device, characterized in that: The communication device comprises means for executing the communication method according to any one of claims 1 to 26.

28. A communication device, characterized in that: The device comprises at least one processor coupled to at least one memory, wherein the at least one processor is used to execute a computer program or instruction stored in the at least one memory so that the communication device executes the communication method according to any one of claims 1 to 26.

29. A chip, characterized in that: It includes at least one processor and a communication interface, wherein the communication interface is used to receive data and / or information and transmit the received data and / or information to the processor, and the processor processes the data and / or information to execute the communication method as described in any one of claims 1 to 26.

30. A computer-readable storage medium, characterized in that: Used to store a computer program, the computer program comprising instructions for implementing the communication method according to any one of claims 1 to 26.

31. A communication system, characterized in that: The communication system includes a first terminal device, a second terminal device and an access network device; Wherein, the first terminal device is used to execute the communication method according to any one of claims 1 to 5, or, the first terminal device is used to execute the communication method according to any one of claims 11 to 19; or, The second terminal device is used to execute the communication method according to any one of claims 6 to 10, or the second terminal device is used to execute the communication method according to any one of claims 20 to 22, or the second terminal device is used to execute the communication method according to claim 26; or The access network device is used to execute the communication method as described in any one of claims 23 to 25.

Images