Communication method and apparatus

Abstract

This application relates to a communication method and apparatus. The target network device transmits first information to the source network device to indicate the reception status of data packets. The target network device receives a first data packet from the source network device, the first data packet being a data packet of a remote device, and the first data packet is determined based on the first information. The remote device is connected to the source network device via a first relay device before the transmission path is switched, and is connected to the target network device after the transmission path is switched. For example, there are one or more first data packets, and the first data packet may include a data packet that has failed to be received by the remote device. In this way, the target network device may transmit to the remote device a data packet that has failed to be received by the remote device in order to reduce the packet loss rate.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the priority of Chinese Patent Application No. 202210919785.7, titled "Communication Method and Apparatus", filed with the China National Intellectual Property Administration on July 30, 2022, and claims the priority of Chinese Patent Application No. 202210952981.4, titled "COMMUNICATION METHOD AND APPARATUS", filed with the China National Intellectual Property Administration on August 9, 2022. Both are hereby incorporated by reference in their entirety into this specification.

[0002] This application relates to the field of communication technologies, and in particular, to communication methods and apparatuses.

Background Art

[0003] In a relay scenario, a remote user equipment (UE) may perform a transmission path switch. This process of transmission path switching is sometimes called a path switch. For example, the remote UE may switch from a direct path between the remote UE and the base station to a path where the remote UE is connected to another base station via a relay UE, or the remote UE may switch from a path for connecting the remote UE to the base station via a relay UE to a path for connecting the remote UE to another base station via another relay UE.

[0004] When a process in which a remote UE performs a transmission path switch is executed in a data transmission process, several problems may occur. For example, a source network device transmits some data packets, and a relay UE may receive some of these data packets and transmit feedback information to the source network device to indicate that these data packets have been received normally. When transferring the data packets to a target network device, the source network device no longer transfers the data packets that have been acknowledged as data packets normally received by the relay UE. However, although the data packets are normally received by the relay UE, the remote UE does not necessarily receive the data packets normally. According to the current mechanism, even if the remote UE fails to receive the data packets, the target network device cannot retransmit the data packets to the remote UE, resulting in a high packet loss rate. Summary of the Invention

[0005] Embodiments of the present application provide a communication method and apparatus for reducing the rate of packet loss caused by a transmission path switch. Means for Solving the Problems

[0006] According to the first aspect, a first communication method is provided. This method may be executed by a target network device, or may be executed by another device including the functions of the target network device, or may be executed by a chip system (or chip) or another functional module. The chip system or functional module can implement the functions of the target network device. The chip system or functional module is disposed, for example, in the target network device. This method includes the step of transmitting first information to a source network device, where the first information indicates the reception status of data packets, and the step of receiving a first data packet from the source network device, where the first data packet is a data packet of a remote device, the first data packet is determined based on the first information, and the remote device is connected to the source network device via a first relay device before the transmission path is switched and is connected to the target network device after the transmission path is switched.

[0007] In the present embodiment of this application, the target network device can indicate the reception status of data packets to the source network device so that the source network device can transmit the first data packet to the target network device. The first data packet is a data packet of a remote device. For example, there are one or more first data packets, and the first data packet may include data packets that have failed to be received by the remote device. In this way, the target network device can transmit the data packets that have failed to be received by the remote device to the remote device in order to reduce the packet loss rate.

[0008] In an optional implementation, the method further includes a step of transmitting a second data packet to the remote device, where the second data packet is determined based on the first data packet. For example, the second data packet may include data packets that failed to be received by the remote device. In other words, after the remote device performs a transmission path switch, the target network device may transmit to the remote device the data packets that failed to be received by the remote device in order to reduce the packet loss amount of the remote device.

[0009] In an optional implementation, after the transmission path switch, the remote device is connected to the target network device via a direct path or an indirect path.

[0010] In an optional implementation, the method further includes a step of receiving second information from the remote device, where the second information indicates data packets that failed to be received by the remote device and / or data packets that were successfully received by the remote device. After performing the transmission path switch, the remote device may transmit the second information to the target network device to indicate the actual reception status of the data packets of the remote device. As a result, based on the second information, the target network device can transmit to the remote device the data packets that failed to be received by the remote device.

[0011] In an optional implementation, the second information is a PDCP status report, or the second information is included in an RRC reconfiguration message, and the RRC reconfiguration message indicates that the remote device has been successfully handed over to the target network device. The implementation of the second information is not limited in this embodiment of the present application.

[0012] In an optional implementation, the first data packet is the second data packet, or the first data packet is part of the second data packet. The first data packet is a data packet that has not been received by the target network device from the source network device before the target network device receives the first data packet. The second data packet further includes another part of the data packet, and the other part of the data packet is a data packet that has been received by the target network device from the source network device before the target network device receives the first data packet, or the second data packet is part of the first data packet. There are multiple possible implementations for the first data packet and the second data packet. For each device, the implementation is flexible.

[0013] In an optional implementation, the method further includes receiving, by the source network device, a third data packet from the source network device before transmitting the first information to the source network device, where the third data packet includes a data packet that the source network device does not receive feedback for and / or a data packet that has not been transmitted by the source network device to the remote device, and the third data packet includes another part of the data packet. For example, the source network device may transfer data to the target network device during a transmission path switch. In this case, the process of the source network device transmitting the first data packet to the target network device may be considered a supplementary data transfer process.

[0014] In an optional implementation form, the step of receiving the first data packet from the source network device is the step of receiving the third data packet from the source network device, where the third data packet includes data packets that the source network device does not receive feedback for and / or data packets that have not been sent by the source network device to the remote device, and the third data packet includes the first data packet. For example, the source network device may not need to transfer data to the target network device during the transmission path switching, but transfers the data to the target network device after the transmission path switching is successful. For example, in addition to sending the first data packet to the target network device, the source network device further sends the third data packet. In this way, fewer interactions between the source network device and the target network device can be performed, and as a result, the source network device can transfer data packets to the target network device at one time.

[0015] In an optional implementation, the third data packet includes data packets not sent by the source network device to the remote device. Data packets not sent by the source network device to the remote device include data packets not associated with a sequence number. The method further includes receiving, from the source network device, third information, where the third information indicates the sequence number of the first data packet not associated with a sequence number. There may be data packets not associated with a sequence number among the data packets transferred by the source network device to the target network device. Thus, the source network device may indicate to the target network device the sequence number of the first data packet not associated with a sequence number, such that the target network device can associate the corresponding sequence number with each data packet not associated with a sequence number accordingly.

[0016] According to a second aspect, a second communication method is provided. This method may be executed by a source network device, or may be executed by another device including the functions of the source network device, or may be executed by a chip system (or chip) or another functional module. The chip system or functional module can implement the functions of the source network device. The chip system or functional module is disposed, for example, within the source network device. This method includes the step of receiving first information from a target network device, where the first information indicates the reception status of data packets, and the step of transmitting a first data packet to the target network device, where the first data packet is a data packet of a remote device, the first data packet is determined based on the first information, and the remote device is connected to the source network device via a first relay device before the transmission path is switched and is connected to the target network device after the transmission path is switched.

[0017] In an optional implementation, the remote device is connected to the target network device via a direct path or an indirect path after the transmission path is switched.

[0018] In an optional implementation, this method further includes the step of transmitting a third data packet to the target network device before receiving the first information from the target network device, where the third data packet includes data packets that the source network device has not received feedback for and / or data packets that have not been transmitted by the source network device to the remote device.

[0019] In an optional implementation, the step of sending the first data packet to the target network device is the step of sending a third data packet to the target network device, where the third data packet includes data packets that the source network device has not received feedback for and / or data packets that have not been sent by the source network device to the remote device, and the third data packet includes the first data packet.

[0020] In an optional implementation, the third data packet includes data packets that have not been sent by the source network device to the remote device, and the data packets that have not been sent by the source network device to the remote device include data packets not associated with a sequence number. The method further includes the step of sending third information to the target network device, where the third information indicates the sequence number of the first data packet not associated with a sequence number.

[0021] For the technical effects brought about by the second aspect or an optional implementation, refer to the description of the technical effects of the first aspect or the corresponding implementation.

[0022] According to a third aspect, a third communication method is provided. This method may be executed by a source network device, or by another device including the functions of the source network device, or by a chip system (or chip) or another functional module. The chip system or functional module can implement the functions of the source network device. The chip system or functional module is disposed, for example, within the source network device. This method includes the step of transmitting fourth information to a remote device, where the fourth information indicates a first data packet and indicates that the remote device stops communicating with a first relay device after receiving the first data packet. The remote device is connected to the source network device via the first relay device before the transmission path is switched, and is connected to the target network device after the transmission path is switched. In this embodiment of the present application, the remote device is disconnected from the first relay device only after receiving the first data packet. In this case, it may be considered that the remote device has received the first data packet and all data packets before the first data packet normally. However, the source network device transmits data packets after the first data packet to the target network device. Therefore, after the remote device executes the transmission path switching, the target network device can continue to transmit data packets to the remote device. This reduces the packet loss amount of the remote device. In addition, the source network device does not need to transmit excessive data packets to the target network device. This can reduce the transmission overhead.

[0023] In an optional implementation, the fourth information is included in a switching command, and the switching command indicates that the remote device executes a transmission path switch. The fourth information may be included in the switching command or may be transmitted separately.

[0024] In an optional implementation, the method further includes the step of transmitting at least one data packet to the target network device, wherein the first data packet in the at least one data packet is the next data packet after the first data packet. Since the source network device uses the fourth information to ensure to a certain extent that the actual reception status of the data packet of the remote device matches the reception status considered by the source network device, the source network device may start transferring data packets to the target network device from the next data packet after the first data packet, and there is no need to send excessive data packets to the target network device. Thereby, the transmission overhead can be reduced.

[0025] In an optional implementation, the at least one data packet includes data packets not associated with a sequence number, and the method further includes the step of transmitting fifth information to the target network device, wherein the fifth information indicates the sequence number of the first data packet not associated with a sequence number. There may be data packets not associated with a sequence number among the data packets transferred from the source network device to the target network device. Therefore, the source network device may indicate to the target network device the sequence number of the first data packet not associated with a sequence number, and as a result, the target network device can associate the corresponding sequence number with each data packet not associated with a sequence number accordingly.

[0026] According to the fourth aspect, a fourth communication method is provided. This method may be executed by a remote device, or may be executed by another device including the functions of the remote device, or may be executed by a chip system (or chip) or another functional module. The chip system or functional module can implement the functions of the remote device. The chip system or functional module is disposed, for example, in the remote device. The remote device is, for example, a terminal device or a network device. This method includes the step of receiving fourth information from a source network device, where the fourth information indicates a first data packet and indicates that the remote device stops communicating with a first relay device after receiving the first data packet. The remote device is connected to the source network device via the first relay device before the transmission path is switched and is connected to the target network device after the transmission path is switched.

[0027] In an optional implementation form, the fourth information is included in a switching command, and the switching command indicates to the remote device to execute a transmission path switch.

[0028] In an optional implementation, after receiving the switching command, if the first data packet has not been received, the method further includes the step of continuing to receive data packets from the first relay device, and when the first data packet is received, or when the first data packet is the first data packet not yet delivered to the upper layer of the PDCP layer, the step of stopping communication with the first relay device. Based on the indication of the fourth piece of information, if the first data packet is not received, the remote device does not need to disconnect from the first relay device even if the remote device receives the switching command. Instead, the remote device may continue to receive data packets from the first relay device until the first data packet is received, and then disconnect from the first relay device. This mechanism is used to ensure that the remote device receives the first data packet and all data packets before the first data packet as normally as possible. In this way, the target network device does not need to send the first data packet and all data packets before the first data packet to the remote device, and the source network device may not need to forward the first data packet and all data packets before the first data packet to the target network device. This helps to reduce transmission overhead.

[0029] For the technical effects brought about by the fourth aspect or some optional implementations, please refer to the description of the technical effects of the third aspect or the corresponding implementations.

[0030] According to a fifth aspect, a fifth communication method is provided. This method may be executed by a source network device, or may be executed by another device including the functions of the source network device, or may be executed by a chip system (or chip) or another functional module. The chip system or functional module can implement the functions of the source network device. The chip system or functional module is disposed, for example, within the source network device. This method includes the step of transmitting at least one data packet to a target network device, where the at least one data packet includes data packets that the source network device predicts the remote device will fail to receive, and the remote device is connected to the source network device via a first relay device before the transmission path is switched and is connected to the target network device after the transmission path is switched. In this embodiment of the present application, the source network device transmits, based on the prediction, data packets that may have failed to be received by the remote device to the target network device. Thus, if the remote device fails to receive the data packets, these data packets may be stored in the target network device. In this case, if the target network device determines, based on the first information, data packets that have failed to be received by the remote device, the target network device may transmit these locally stored data packets to the remote device, and there is no need to request data packets from the source network device. In this way, the process of interaction between the target network device and the source network device is reduced, the signaling overhead is reduced, and the delay in data acquisition by the remote device is reduced.

[0031] In an optional implementation, the method further includes a step of transmitting fourth information to a remote device, where the fourth information indicates a first data packet and indicates that after the remote device receives the first data packet, communication with a first relay device is stopped.

[0032] In an optional implementation, the fourth information is included in a switching command, and the switching command indicates to the remote device to perform a transmission path switch.

[0033] In an optional implementation, at least one data packet includes a data packet not associated with a sequence number, and the method further includes a step of transmitting fifth information to a target network device, where the fifth information indicates the sequence number of the first data packet not associated with a sequence number.

[0034] For the technical effects brought about by the fifth aspect or some optional implementations, refer to the description of the technical effects of the third aspect or the corresponding implementation.

[0035] According to the sixth aspect, a sixth communication method is provided. This method may be executed by a source network device, or may be executed by another device including the functions of the source network device, or may be executed by a chip system (or chip) or another functional module. The chip system or functional module can implement the functions of the source network device. The chip system or functional module is disposed, for example, within the source network device. This method includes the step of sending a switching command to a remote device, where the switching command indicates to the remote device to execute a transmission path switch. The remote device is connected to the source network device via a first relay device before the transmission path switch and is connected to a target network device after the transmission path switch, and the step of receiving sixth information from the remote device, where the sixth information indicates data packets that the remote device has failed to receive and / or data packets that the remote device has received successfully. In this embodiment of the present application, the remote device may use the sixth information to indicate the actual reception status of the remote device to the source network device. The source network device knows the actual reception status of the remote device and thus may transfer the data packets that the remote device has failed to receive to the target network device. After the remote device executes the transmission path switch, the target network device may send these data packets to the remote device, and there is no need to request these data packets from the source network device. This can reduce the interaction process between the target network device and the source network device and also reduce the packet loss amount of the remote device.

[0036] In an optional implementation, the switching command further includes seventh information, and the seventh information indicates to send reception status information to the remote device. The source network device may trigger the remote device to send the sixth information, as a result, the implementation of the remote device is simplified.

[0037] In an optional implementation, the method further includes the step of sending at least one data packet to the target network device, where the at least one data packet includes data packets that failed to be received by the remote device. Since the source network device knows the actual reception status of the remote device, the source network device may send the data packets that failed to be received by the remote device to the target network device, and the source network device may not send the data packets that were successfully received by the remote device to the target network device. In this way, the packet loss rate can be reduced, and the transmission overhead can also be reduced.

[0038] In an optional implementation, the at least one data packet further includes data packets that have not been sent by the source network device to the remote device. The source network device may further send some data packets that have not been sent to the remote device within the time to the target network device, and the target network device sends the data packets to the remote device.

[0039] In an optional implementation, data packets not sent by the source network device to the remote device include data packets not associated with a sequence number, and the method further includes the step of sending eighth information to the target network device, where the eighth information indicates the sequence number of the first data packet not associated with a sequence number. There may be data packets not associated with a sequence number among the data packets transferred by the source network device to the target network device. Therefore, the source network device may indicate to the target network device the sequence number of the first data packet not associated with a sequence number, so that the target network device can associate the corresponding sequence number with each data packet not associated with a sequence number accordingly.

[0040] According to a seventh aspect, a seventh communication method is provided. The method may be executed by a remote device, or may be executed by another device including the functions of the remote device, or may be executed by a chip system (or chip) or another functional module. The chip system or functional module can implement the functions of the remote device. The chip system or functional module is disposed, for example, in the remote device. The remote device is, for example, a terminal device or a network device. The method includes the step of receiving a switching command from the source network device, where the switching command indicates to execute a transmission path switch for the remote device, and the remote device is connected to the source network device via a first relay device before the transmission path switch and is connected to the target network device after the transmission path switch, and the step of sending sixth information to the source network device, where the sixth information indicates data packets that failed to be received by the remote device and / or data packets that were successfully received by the remote device.

[0041] In an optional implementation, the switching command further includes seventh information, and the seventh information indicates to send reception status information to the remote device.

[0042] For the technical effects brought about by the seventh aspect or the optional implementation, reference may be made to the description of the technical effects of the sixth aspect or the corresponding implementation.

[0043] According to an eighth aspect, an eighth communication method is provided. This method may be executed by the first relay device, or may be executed by another device including the functions of the first relay device, or may be executed by a chip system (or chip) or another functional module. The chip system or the functional module can implement the functions of the first relay device. The chip system or the functional module is disposed, for example, in the first relay device. The first relay device is, for example, a terminal device or a network device. This method includes the steps of receiving a first data packet from a source network device, sending the first data packet to a remote device, where the remote device is connected to the source network device via the first relay device before the transmission path is switched, receiving first feedback information from the remote device, where the first feedback information indicates whether the first data packet was successfully received or the reception failed, and sending second feedback information to the source network device based on the first feedback information, where the second feedback information indicates whether the first data packet was successfully received or the reception failed.

[0044] According to a ninth aspect, a communication device is provided. The communication device can be a target network device according to the first aspect. The communication device has the function of the target network device. The communication device is, for example, a target network device, or a large device including the target network device, or a functional module within the target network device, such as a baseband device or a chip system. In an optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (which may also be referred to as a processing module) and a transceiver unit (which may also be referred to as a transceiver module). The transceiver unit can implement a transmission function and a reception function. When the transceiver unit implements the transmission function, the transceiver unit may be referred to as a transmission unit (or may also be referred to as a transmission module). When the transceiver unit implements the reception function, the transceiver unit may be referred to as a reception unit (or may also be referred to as a reception module). The transmission unit and the reception unit may be the same functional module, and the functional module is referred to as the transceiver unit, and the functional module can implement a transmission function and a reception function. Alternatively, the transmission unit and the reception unit may be different functional modules, and the transceiver unit is a general term for these functional modules.

[0045] In an optional implementation, the transceiver unit (or the transmission unit) is configured to transmit first information to the source network device, the first information indicates the reception status of data packets, and the transceiver unit (or the reception unit) is configured to receive a first data packet from the source network device, the first data packet is a data packet of the remote device, the first data packet is determined based on the first information, and the remote device is connected to the source network device via a first relay device before the transmission path is switched and is connected to the target network device after the transmission path is switched.

[0046] In an optional implementation, the communication device further includes a memory unit (which may also be referred to as a memory module). The processing unit is coupled to the memory unit and configured to execute a program or instruction in the memory unit to enable the communication device to execute the functions of the target network device according to the first aspect.

[0047] According to a tenth aspect, a communication device is provided. The communication device may be a source network device according to the second aspect, the third aspect, the fifth aspect, or the sixth aspect. The communication device has the functions of the source network device. The communication device is, for example, a source network device, or a large device including the source network device, or a functional module within the source network device, such as a baseband device or a chip system. In an optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (which may also be referred to as a processing module) and a transceiver unit (which may also be referred to as a transceiver module). For the implementation of the transceiver unit, refer to the description of the ninth aspect.

[0048] In an optional implementation, the transceiver unit (or receiving unit) is configured to receive first information from the target network device, where the first information indicates the reception status of data packets, and the transceiver unit (or transmitting unit) is configured to transmit a first data packet to the target network device, where the first data packet is a data packet of a remote device, the first data packet is determined based on the first information, and the remote device is connected to the source network device via a first relay device before the transmission path is switched and is connected to the target network device after the transmission path is switched.

[0049] In an optional implementation, the transceiver unit (or the transmission unit) is configured to transmit fourth information to the remote device, where the fourth information indicates the first data packet and indicates that the remote device stops communicating with the first relay device after receiving the first data packet. The remote device is connected to the source network device via the first relay device before the transmission path is switched, and is connected to the target network device after the transmission path is switched.

[0050] In an optional implementation, the transceiver unit (or the transmission unit) is configured to transmit at least one data packet to the target network device, where the at least one data packet includes a data packet that the source network device predicts the remote device will fail to receive. The remote device is connected to the source network device via the first relay device before the transmission path is switched, and is connected to the target network device after the transmission path is switched.

[0051] In an optional implementation, the transceiver unit (or the transmission unit) is configured to transmit a switching command to the remote device, where the switching command indicates that the remote device executes a transmission path switch. The remote device is connected to the source network device via the first relay device before the transmission path is switched, and is connected to the target network device after the transmission path is switched. The transceiver unit (or the receiving unit) is configured to receive sixth information from the remote device, where the sixth information indicates data packets that the remote device failed to receive and / or data packets that the remote device received successfully.

[0052] In an optional implementation, the communication device further includes a storage unit (which may also be referred to as a storage module). The processing unit is coupled to the storage unit and configured to execute a program or instructions in the storage unit to enable the communication device to perform the functions of the source network device according to the second, third, fifth, or sixth aspect.

[0053] According to an eleventh aspect, a communication device is provided. The communication device may be a remote device according to the fourth aspect or the seventh aspect. The communication device has the functions of a remote device. The communication device is, for example, a remote device, or a large device including a remote device, or a functional module within a remote device, such as a baseband device or a chip system. In an optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (which may also be referred to as a processing module) and a transceiver unit (which may also be referred to as a transceiver module). For the implementation of the transceiver unit, refer to the description of the sixth aspect.

[0054] In an optional implementation, the transceiver unit (or the receiving unit) is configured to receive fourth information from the source network device, where the fourth information indicates a first data packet and indicates that the remote device stops communicating with the first relay device after receiving the first data packet. The remote device is connected to the source network device via the first relay device before the transmission path is switched and is connected to the target network device after the transmission path is switched.

[0055] In an optional implementation form, the transceiver unit (or the receiving unit) is configured to receive a switching command from the source network device, the switching command indicates to execute a transmission path switching on the remote device, the remote device is connected to the source network device via a first relay device before the transmission path switching, and is connected to the target network device after the transmission path switching, the transceiver unit (or the transmitting unit) is configured to transmit sixth information to the source network device, and the sixth information indicates data packets that have failed to be received by the remote device and / or data packets that have been successfully received by the remote device.

[0056] In an optional implementation form, the communication device further includes a storage unit (which may also be referred to as a storage module). The processing unit is coupled to the storage unit and configured to execute a program or instruction in the storage unit to enable the communication device to perform the functions of the remote device according to the fourth aspect or the seventh aspect.

[0057] According to a twelfth aspect, a communication device is provided. The communication device may be a first relay device according to the eighth aspect. The communication device has the functions of the first relay device. The communication device is, for example, the first relay device, or a large device including the first relay device, or a functional module within the first relay device, such as a baseband device or a chip system. In an optional implementation form, the communication device includes a baseband device and a radio frequency device. In another optional implementation form, the communication device includes a processing unit (which may also be referred to as a processing module) and a transceiver unit (which may also be referred to as a transceiver module). For the implementation form of the transceiver unit, please refer to the description of the sixth aspect.

[0058] In an optional implementation form, the transceiver unit (or receiving unit) is configured to receive a first data packet from a source network device, the transceiver unit (or transmitting unit) is configured to transmit the first data packet to a remote device, the remote device is connected to the source network device via a first relay device before the transmission path is switched, the transceiver unit (or receiving unit) is configured to receive first feedback information from the remote device, the first feedback information indicates whether the first data packet is received successfully or fails to be received, the transceiver unit (or transmitting unit) is configured to transmit second feedback information to the source network device based on the first feedback information, and the second feedback information indicates whether the first data packet is received successfully or fails to be received.

[0059] In an optional implementation form, the communication device further includes a storage unit (which may also be called a storage module). The processing unit is coupled to the storage unit and configured to execute a program or instruction in the storage unit to enable the communication device to execute the function of the first relay device according to the eighth aspect.

[0060] According to the thirteenth aspect, a first communication system including a target network device and a source network device is provided. The target network device is configured to execute the communication method according to the first aspect, and the source network device is configured to execute the communication method according to the second aspect.

[0061] According to the fourteenth aspect, a second communication system including a source network device is provided. The source network device is configured to execute the communication method according to the third aspect or the fifth aspect.

[0062] Optionally, the second communication system further includes a remote device configured to execute a communication method according to the fourth aspect.

[0063] According to a fifteenth aspect, a third communication system including a remote device and a source network device is provided, the remote device is configured to execute a communication method according to the seventh aspect, and the source network device is configured to execute a communication method according to the sixth aspect.

[0064] According to a sixteenth aspect, a fourth communication system is provided that includes a first relay device configured to execute a communication method according to the eighth aspect.

[0065] According to a seventeenth aspect, a computer-readable storage medium is provided, the computer-readable storage medium is configured to store a computer program or instructions, and when the computer program or instructions are executed, the methods executed by the remote device, the first relay device, the target network device, or the source network device in the foregoing aspects are implemented.

[0066] According to an eighteenth aspect, a computer program product including instructions is provided. When the computer program product is executed on a computer, the methods in each of the foregoing aspects are implemented.

[0067] According to a nineteenth aspect, a chip system including a processor and an interface is provided. The processor is configured to call instructions from the interface and execute the instructions to enable the chip system to implement the methods in each of the foregoing aspects.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0069] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0070] In an embodiment of the present application, the terminal device is a device having a wireless transceiver function, and can be a fixed device, a mobile device, a handheld device (e.g., a mobile phone), a wearable device, an in-vehicle device, or a wireless device incorporated in the aforementioned devices (e.g., a communication module, a modem, or a chip system). The terminal device is configured to connect people, objects, machines, etc., and can be widely used in various scenarios including, but not limited to, scenarios such as cellular communication, device-to-device (D2D) communication, vehicle-to-everything (V2X), machine-to-machine / machine-type communications (M2M / MTC), internet of things (IoT), virtual reality (VR), augmented reality (AR), industrial control, self-driving, remote medical, smart grid, smart furniture, smart office, smart ware, smart transportation, smart city, unmanned aerial vehicle, robot, etc. The terminal device may also be referred to as a user equipment (UE), a terminal, an access station, a UE station, a remote station, a wireless communication device, a user device, etc. For ease of explanation, in an embodiment of the present application, an example where the terminal device is a UE is used in the explanation.

[0071] In an embodiment of the present application, the network device includes, for example, an access network device and / or a core network device. The access network device is a device having a wireless transceiver function and is configured to communicate with a terminal device. The access network device includes, but is not limited to, a base station (base transceiver station (BTS), NodeB, eNodeB / eNB, or gNodeB / gNB), a transmission reception point (TRP), a subsequent evolved base station in the 3rd generation partnership project (3GPP (registered trademark)), an access node in a wireless fidelity (Wi-Fi) system, a wireless relay node, a wireless backhaul node, etc. The base station can be a macro base station, a micro base station, a pico cell base station, a small cell, a relay station, etc. A plurality of base stations may support a network using the same access technology or may support a network using different access technologies. The base station may include one or more co-site or non-co-site transmission reception points. Alternatively, the access network device may be a wireless controller, a centralized unit (CU), and / or a distributed unit (DU) in a cloud radio access network (CRAN) scenario. Alternatively, the access network device may be a server or the like. For example, the access network device in vehicle to everything (V2X) technology may be a road side unit (RSU). In the following, an example where the access network device is a base station is used to provide an explanation. The base station may communicate with the terminal device or may communicate with the terminal device through a relay station. The terminal device may communicate with a plurality of base stations in different access technologies.The core network device is configured to implement functions such as mobility management, data processing, session management, policy, and charging. The name of the device that implements the core network function in a system using different access technologies may be different. This is not limited in the embodiments of the present application. For example, a 5G system is used. The core network device includes an access and mobility management function (AMF), a session management function (SMF), a policy control function (PCF), a user plane function (UPF), and the like.

[0072] In the embodiments of the present application, a communication device configured to implement the functions of a network device may be a network device, or a device that can support a network device when implementing the functions, such as a chip system. The device may be installed in the network device. In the technical solutions provided in the embodiments of the present application, the technical solutions provided in the embodiments of the present application are described using an example in which a device configured to implement the functions of a network device is a network device.

[0073] In the embodiments of the present application, unless otherwise specified, the number of nouns represents "singular noun or plural noun", that is, "one or more". "At least one" means one or more, and "a plurality of" means two or more. "And / or" describes the relationship between related objects and indicates that three relationships can exist. For example, A and / or B can indicate the following three cases, that is, the case where only A exists, the case where both A and B exist, and the case where only B exists, and A and B can be singular or plural. The character " / " usually indicates the "or" relationship between related objects. For example, A / B indicates A or B. "At least one of the following items" or a similar expression means any combination of these items, including a single item or any combination of multiple items. For example, at least one of a, b, or c indicates a, b, c, a and b, a and c, b and c, or a, b, and c, and a, b, and c can be singular or plural.

[0074] Ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, but are not used to limit the size, content, order, time series, priority, importance, etc. of multiple objects. For example, the first information and the second information may be the same information or different information. In addition, the name does not indicate differences in the content, size, transmission end / reception end, priority, importance, etc. of the two pieces of information. In addition, the step numbers in the embodiments described in the present application are only used to distinguish different steps and are not used to limit the order of the steps. For example, S301 may be executed before S302, after S302, or simultaneously with S302.

[0075] The technical solutions provided in the embodiments of this application may be applied to a 4th generation (4G) mobile communication technology system, such as a Long Term Evolution (LTE) system, or may be applied to a 5th generation (5G) mobile communication technology system, such as a New Radio (NR) system, or may be applied to a next-generation mobile communication system or another similar communication system, such as a 6th generation (6G) mobile communication technology system. This is not specifically limited. In addition, the technical solutions provided in the embodiments of this application may be applied to a device-to-device (D2D) scenario, such as an NR-D2D scenario, or may be applied to a vehicle-to-everything (V2X) scenario, such as an NR-V2X scenario or a vehicle-to-vehicle (V2V) scenario. Alternatively, the technical solutions provided in the embodiments of this application may be applied to fields such as intelligent driving, assisted driving, or intelligent connected vehicles. When the technical solution is applied to a D2D scenario, both the relay device and the remote device may be UEs. When the technical solution is applied to a non-D2D scenario, one of the relay device or the remote device may be a UE, and the other device may be a network device (e.g., an access network device), or both the remote device and the relay device may be network devices. In each of the following embodiments of this application, the remote device is, for example, a UE or a network device, and the relay device is, for example, a UE or a network device.

[0076] This application relates to a UE-to-network relay mechanism, which can be used to improve the coverage of a cellular network. FIGS. 1A and 1B are diagrams of two application scenarios according to embodiments of this application. In FIG. 1A, a remote device is first connected to an access network device 1 via a relay device. After the transmission path switching is executed, it is considered that the remote device is connected to an access network device 2 via the Uu interface, or the remote device is directly connected to the access network device 2. Such a scenario is considered as an inter gNB process of switching from an indirect path to a direct path (indirect link→direct link). In FIG. 1B, a remote device is first connected to an access network device 1 via a relay device 1. After the transmission path switching is executed, the remote device is connected to an access network device 2 via a relay device 2. Such a scenario is considered as an inter gNB process of switching from an indirect path to an indirect path (indirect link→indirect link).

[0077] The scenario shown in Figure 1A is used as an example. Refer to Figure 2. If the transmission path switching executed by the remote UE is a process within the data transmission process, several problems may occur. The access network device 1 in Figure 1A transmits data packets with sequence numbers {0, 1, 2, 3, 4, 5, 6, 7}. The relay device receives data packets with sequence numbers {0, 1, 2, 4, 6}, and in order to indicate that the data packets with sequence numbers {0, 1, 2, 4, 6} have been successfully received, it sends radio link control (RLC) feedback to the access network device 1. Based on the RLC positive acknowledgment feedback, the access network device 1 determines that the receiving side has successfully received the data packets with sequence numbers {0, 1, 2, 4, 6}. When the relay device sends the data packets with sequence numbers {0, 1, 2, 4, 6} to the remote device, if the remote device receives a path switching command from the access network device 1, the remote device may disconnect from the relay device. In this case, the remote device only receives the data packet with sequence number {0} from the relay device and does not receive the data packets with sequence numbers {1, 2, 4, 6}. In other words, the data packets with sequence numbers {1, 2, 3, 4, 5, 6, 7} have not been received by the remote device. However, when transferring the remote device's data packets to the access network device 2, the access network device 1 does not transfer the data packets that have been confirmed to be successfully received. Therefore, the access network device 1 transfers the data of the data packets with sequence numbers {3, 5, 7} to the access network device 2 based on the RLC feedback from the relay device. After the remote device switches its transmission path to the access network device 2, the access network device 2 only retransmits the data packets with sequence numbers {3, 5, 7} to the remote device.As a result, the remote device cannot receive data packets with sequence numbers {1, 2, 4, 6}.

[0078] In view of this, a technical solution in an embodiment of the present application is provided. In an embodiment of the present application, the target network device may indicate the reception status of data packets to the source network device so that the source network device can send a first data packet to the target network device. The first data packet is a data packet of the remote device. For example, there are one or more first data packets, and the first data packet may include data packets that have failed to be received by the remote device. In this way, the target network device may send data packets that have failed to be received by the remote device to the remote device in order to reduce the packet loss rate.

[0079] To better explain the embodiments of the present application, the following will describe the methods provided in the embodiments of the present application with reference to the accompanying drawings. In the accompanying drawings corresponding to the embodiments of the present application, all steps represented by dashed lines are optional steps. The methods provided in each embodiment of the present application can be applied to the network architectures shown in FIG. 1A or FIG. 1B. For example, the remote device described below is, for example, the remote device shown in FIG. 1A or FIG. 1B, the source network device described below is, for example, the access network device 1 shown in FIG. 1A or FIG. 1B, the target network device described below is, for example, the access network device 2 shown in FIG. 1A or FIG. 1B, and the first relay device described below is, for example, the relay device shown in FIG. 1A or the relay device 1 shown in FIG. 1B. From FIG. 1A or FIG. 1B, it can be found that in the embodiments of the present application, the remote device is connected to the source network device via the first relay device before the transmission path is switched, and is connected to the target network device after the transmission path is switched. After performing the transmission path switching, the remote device may be connected to the target network device via a direct path or an indirect path. The direct path is a path for communication via the Uu interface, and the indirect path is a path for connecting to the target network device via, for example, a second relay device (for example, the relay device 2 shown in FIG. 1B).

[0080] In the embodiments of the present application, the "direct path" is a path through which the remote device communicates with the access network device (or the cell provided by the access network device) via the Uu interface without passing through a relay device, and the "indirect path" is a path through which the remote device communicates with the access network device (or the cell provided by the access network device) via a relay device. In addition, the "path" may be alternatively replaced by a "link". For example, the "direct path" may be referred to as a "direct link", and the "indirect path" may be referred to as an "indirect link".

[0081] In an embodiment of the present application, Device A sends a message to Device B. In the case of Device B, the message may be considered to be from Device A. The transmission process may be a direct transmission or an indirect transmission (for example, a transfer via another device).

[0082] To solve the technical problems to be solved in the present application, embodiments of the present application provide a plurality of methods. First, refer to FIG. 3 which is a flowchart of a first communication method according to an embodiment of the present application.

[0083] S301: The target network device sends the first information to the source network device. Correspondingly, the source network device receives the first information from the target network device.

[0084] The first information may indicate the reception status of data packets, or may indicate data transfer (or may be used to request data transfer). For example, the reception status of data packets indicated by the first information may include the status for receiving data packets by a remote device and / or the status for receiving data packets by the target network device. The data packets indicated by the first information may be data packets of a remote device. When the first information is used to request data transfer, the first information may be used to request to transfer the data packets of the remote device.

[0085] Optionally, before S301, the method may further include S302: a step in which the remote device sends second information to the target network device. Correspondingly, the target network device receives the second information from the remote device. The second information may indicate data packets that the remote device failed to receive and / or data packets that the remote device received successfully. For example, after the remote device switches the transmission path to the path through which the remote device is connected to the target network device, or after the remote device successfully executes the switching of the transmission path, the remote device may send the second information to the target network device. For example, the second information may be a packet data convergence protocol (PDCP) status report, or the second information may be other information. The second information may be sent separately, or the second information may be carried in a message indicating that the path switching was successful. For example, the remote device may send a radio resource control (RRC) reconfiguration message to the target network device to indicate that the remote device successfully executed the transmission path switching or to indicate that the remote device was successfully handed over to the target network device. In this case, the second information may be included in the RRC reconfiguration message. When the target network device receives the second information, the first information in S301 may be determined based on the second information.

[0086] For example, if a part of the information needs to indicate M data packets, the indication method may be that the information may include the indexes of the M data packets. For example, if the first information indicates data packets with sequence numbers {1, 2, 4, 6}, the first information may include the sequence numbers {1, 2, 4, 6}.

[0087] Alternatively, when a part of the information needs to indicate M data packets, another indication method is that the information may include the index of the first data packet within the M data packets. For example, if the first information indicates data packets with sequence numbers {1, 2, 4, 6}, or if the first information indicates data packets with sequence numbers {1, 2, 3, 4, 5, 6, 7}, the first information may include the sequence number {1}. In the indication method where the information includes the index of the first data packet, the first information is equivalent to indicating the data packet with sequence number {1} and all other data packets that come after the data packet with sequence number {1}. For example, the first information indicates data packets with sequence numbers {1, 2, 3, 4, 5, 6, 7}.

[0088] Alternatively, when part of the information needs to indicate M data packets, yet another indication method is that the information may include the index of the first data packet among the M data packets and indicates the reception status of the remaining data packets within the M data packets. For example, when the first information indicates data packets with sequence numbers {1, 2, 3, 4, 5, 6, 7}, the first information may include the sequence number {1}, and the first information may include a bitmap. The number of bits included in the bitmap is the same as the number of bits of the remaining data packets within the M data packets. For example, the bitmap includes 6 bits, and the 6 bits correspond one-to-one to the data packets with sequence numbers {2, 3, 4, 5, 6, 7}. Alternatively, the number of bits included in the bitmap is a multiple of 8. For example, the bitmap includes 8 bits, and the first 6 bits correspond one-to-one to the data packets with sequence numbers {2, 3, 4, 5, 6, 7}. The value of each bit may indicate the reception status of the corresponding data packet. For example, when the value of 1 bit within the bitmap is "0", it indicates that the data packet corresponding to that bit has failed to be received; or when the value of 1 bit is "1", it indicates that the data packet corresponding to that bit has been successfully received. For example, when the second information is a PDCP status report, the second information can thus indicate the data packets successfully received by the remote device and / or the data packets that have failed to be received by the remote device. The PDCP status report includes a count or sequence number information and a bitmap. The status report uses the included count or sequence number information to indicate the count corresponding to the first data packet that has failed to be received, for example, the first missing count (FMC), or the sequence number corresponding to the first data packet that has failed to be received, for example, the first missing SN (FMS). In this case, it indicates that all other data packets before the data packet indicated by the information have been successfully received.The length of the bitmap included in the PDCP status report can be a multiple of 8, and the bitmap can indicate the reception status of data packets after the first data packet that failed to be received. For example, the count of the first data packet that failed to be received is {3}, in other words, all other data packets before the data packet with a count of {3} were received normally, and the counts of data packets after the data packet that was received normally and has a count of {3} are {5,9}. In this case, FMC = 3. Since all other data packets after the data packet with a count of {9} were not received normally, the length of the bitmap is 8, and "0100 0100" can indicate that the data packets with counts of {5,9} were received normally.

[0089] The first information and the second information may have multiple implementation forms. Hereinafter, the implementation forms will be described using examples.

[0090] 1. Embodiment 1 of the second information The second information indicates data packets that failed to be received by the remote device. For example, the second information may indicate only the data packets that failed to be received by the remote device. In this indication method, the second information may indicate only the data packets that failed to be received by the remote device. For example, if the remote device fails to receive data packets with sequence numbers {1, 2, 4, 6}, the second information may indicate the data packets with sequence numbers {1, 2, 4, 6}. For example, the second information may include the sequence numbers {1, 2, 4, 6}. In the embodiments of the present application, the serial number of a data packet is, for example, the sequence number (SN) of the data packet or the count of the data packet. For example, the "sequence number" described in the embodiments of the present application may be alternatively replaced by the "serial number" or the "count". The count of a data packet may be determined based on the HFN and SN of the data packet. For example, the count of one data packet may be composed of the HFN and SN of the data packet.

[0091] In the first implementation form of the second information, the first information may be the same as the second information. For example, after receiving the second information, the target network device may transfer the second information to the source network device. In this case, the first information is the same as the second information. In this case, the first information may indicate the reception status of the data packets of the remote device.

[0092] Alternatively, the first information may be different from the second information.

[0093] For example, the second information indicates only the data packets that failed to be received by the remote device, and the first information may indicate the first data packet within the data packets that failed to be received by the remote device in order to indicate all data packets from the first data packet to the last data packet of the remote device. In this case, the first information may indicate the reception status of the data packets of the remote device. For example, the second information includes sequence numbers {1, 2, 4, 6} to indicate that data packets with sequence numbers {1, 2, 4, 6} failed to be received, and the first information may include sequence number {1} in order to indicate all data packets from the data packet with sequence number {1} to the last data packet of the remote device. The last data packet of the remote device is, for example, the last data packet transmitted to the remote device by the source network device via the first transmission path, or the last data packet within the data packets that should be transmitted to the remote device by the source network device via the first transmission path. In this case, the last data packet may or may not be transmitted to the remote device via the first transmission path. In this case, in addition to the data packets that failed to be received by the remote device, the data packets indicated by the first information may further include data packets that were successfully received by the remote device and / or data packets that were not received by the remote device. The data packets that were not received by the remote device are, for example, data packets that were not transmitted to the remote device, and may include data packets associated with sequence numbers and / or data packets not associated with sequence numbers.

[0094] In another example, after receiving the second information, the target network device may further determine the first information based on the second information and the data packets stored in the target network device. In this case, the first information may indicate the reception status of the data packets of the remote device and / or the reception status of the data packets of the target network device. For example, the target network device may determine whether the data packets stored in the target network device are present within the data packets indicated by the second information. If the data packets stored in the target network device are present within the data packets indicated by the second information, the first information may indicate the data packets not stored in the target network device instead of indicating the data packets stored in the target network device. The data packets stored in the target network device are, for example, the data packets received by the target network device from the source network device by data forwarding. For example, the second information indicates the reception status of the data packets of the remote device. For example, the second information indicates that the reception of the data packets with sequence numbers {1, 2, 4, 6} and the data packets after the data packet with sequence number {6} has failed. After receiving the second information, the target network device determines that the data packets with sequence numbers {4, 6} and the data packets after the data packet with sequence number {6} have been obtained by data forwarding.In this case, the first information may indicate a data packet with a sequence number of {1, 2}, or the first information may indicate all data packets starting from the data packet with a sequence number of {1} up to the last data packet of the remote device, or to indicate all data packets starting from the data packet with a sequence number of {1} up to the first data packet transferred from the source network device to the target network device by the target network device, the data packet with a sequence number of {1} may be indicated.

[0095] 2. Embodiment 2 of the second information The second information indicates the data packets normally received by the remote device. For example, the second information may indicate only the data packets normally received by the remote device. In this indication method, the second information may indicate only the data packets normally received by the remote device. For example, if the remote device fails to receive data packets with sequence numbers of {1, 2, 4, 6} but successfully receives data packets with sequence numbers of {0, 3, 5, 7}, the second information may indicate the data packets with sequence numbers of {0, 3, 5, 7}. For example, the second information may include sequence numbers {0, 3, 5, 7}.

[0096] In Embodiment 2 of the second information, the first information may be the same as the second information. For example, after receiving the second information, the target network device may transfer the second information to the source network device. In this case, the first information is the same as the second information. In this case, the first information may indicate the reception status of the data packets of the remote device.

[0097] Alternatively, the first information may be different from the second information.

[0098] For example, the second information may indicate only the data packets successfully received by the remote device, and the first information may indicate the data packets that failed to be received by the remote device. In this case, the first information may indicate the reception status of the data packets of the remote device. For example, the second information includes sequence numbers {0, 3, 5, 7} to indicate that data packets with sequence numbers {0, 3, 5, 7} were successfully received, and the first information may include sequence numbers {1, 2, 4, 6} to indicate data packets with sequence numbers {1, 2, 4, 6}.

[0099] In another example, the second information indicates only the data packets successfully received by the remote device, and the first information may indicate the first data packet within the data packets that failed to be received by the remote device to indicate all data packets from the first data packet to the last data packet of the remote device. In this case, the first information may indicate the reception status of the data packets of the remote device. For example, the second information includes sequence numbers {0, 3, 5, 7} to indicate that data packets with sequence numbers {0, 3, 5, 7} were successfully received. In this case, the target network device may determine that the remote device failed to receive data packets with sequence numbers {1, 2, 4, 6}, and the first information may include sequence number {1} to indicate all data packets from the data packet with sequence number {1} to the last data packet of the remote device. For the description of the last data packet of the remote device and the content indicated by the first information, please refer to the foregoing description.

[0100] In another example, after receiving the second information, the target network device may further determine the first information based on the second information and the data packets stored in the target network device. In this case, the first information may indicate the reception status of the data packets of the remote device and / or the reception status of the data packets of the target network device. For example, the target network device may determine whether the data packets stored in the target network device are present within the data packets not indicated by the second information. If the data packets stored in the target network device are present within the data packets not indicated by the second information, the first information may indicate the data packets not stored in the target network device instead of the data packets stored in the target network device. The data packets stored in the target network device are, for example, the data packets received by the target network device from the source network device by data transfer. For example, the second information indicates only the data packets successfully received by the remote device. For example, the second information includes the sequence numbers {0, 3, 5, 7} to indicate that the data packets with the sequence numbers {0, 3, 5, 7} have been successfully received. In this case, the target network device may determine that the remote device has failed to receive the data packets with the sequence numbers {1, 2, 4, 6} and the data packets after the data packet with the sequence number {6}. For example, the target network device determines that the data packets with the sequence numbers {4, 6} and the data packets after the data packet with the sequence number {6} have been obtained by data transfer. In this case, the first information may indicate the data packets with the sequence numbers {1, 2}.Alternatively, the first information may indicate the data packet with the sequence number \{1\} and all data packets from the data packet with the sequence number \{1\} to the last data packet of the remote device, or all data packets from the data packet with the sequence number \{1\} to all data packets up to the data packet immediately before the first data packet transferred from the source network device to the target network device by the source network device in order to indicate all data packets up to the data packet immediately before the first data packet transferred from the source network device to the target network device by the source network device.

[0101] 3. Embodiment 3 of the second information The second information indicates one or more of the following, namely, data packets that failed to be received by the remote device, data packets that were successfully received by the remote device, or data packets that have not been received by the remote device. For example, the second information may indicate the first data packet within the data packets that failed to be received by the remote device in order to indicate all data packets from the first data packet to the last data packet of the remote device. For an explanation of the last data packet of the remote device, refer to the foregoing explanation. For example, if the remote device fails to receive data packets with sequence numbers {1, 2, 4, 6}, the second information may indicate the data packet with sequence number {1}. For example, the second information may include the sequence number {1} in order to indicate data packets with sequence numbers {1, 2, 3, 4, 5, 6, 7}. The data packet with sequence number {7} is, for example, the last data packet sent by the source network device to the remote device, or the last data packet within the data packets to be sent by the source network device to the remote device. When the second information indicates the first data packet within the data packets that failed to be received by the remote device, in addition to the data packets that failed to be received by the remote device, the data packets indicated by the second information may further include data packets that were successfully received by the remote device and / or data packets that have not been received by the remote device. Data packets that have not been received by the remote device are, for example, data packets that have not been sent to the remote device, and may include data packets associated with a sequence number and / or data packets not associated with a sequence number.

[0102] In another example, the second information indicates the reception status of data packets of the remote device. For example, the second information is a PDCP status report, or the second information is included in an RRC reconfiguration complete message. For example, the second information included in the RRC reconfiguration complete message indicates the reception status corresponding to the DRB ID. For example, the second information indicates the reception status of the first data packet that failed to be received by the remote device and the reception status of the data packets after the first data packet that failed to be received. For example, the second information is FMC = 3, indicating that the bitmap is "0100 0100". Under this indication, the second information indicates that the count of the first data packet that failed to be received by the remote device is {3}, in other words, all the data packets before the data packet with a count of {3} were received normally, the count of the data packets received normally and the data packets after the data packet with a count of {3} is {5,9}, and the remaining data packets were not received normally. In another example, the second information is FMS = 3, indicating that the bitmap is "0100 0100". Under this indication, the second information indicates that the sequence number of the first data packet that failed to be received by the remote device is {3}, in other words, all the data packets before the data packet with a sequence number of {3} were received normally, the sequence numbers of the data packets received normally and after the data packet with a sequence number of {3} are {5,9}, and the remaining data packets were not received normally. The data packets that failed to be received may include data packets associated with a sequence number and / or data packets not associated with a sequence number. In another example, the second information further includes a DRB ID. For example, when the second information indicates that the DRB ID = 3 and FMC = 3, it indicates that for the DRB of the remote device with a DRB ID of 3, all other data packets before the data packet with a count of {3} were received normally.

[0103] In the third implementation form of the second information, the first information may be the same as the second information. For example, after receiving the second information, the target network device may transfer the second information to the source network device. In this case, the first information is the same as the second information. In this case, the first information may indicate the reception status of the data packets of the remote device. Compared with the second information, the first information may further include a DRB ID to indicate the reception status of the DRB corresponding to the remote device.

[0104] Alternatively, the first information may be different from the second information.

[0105] For example, after receiving the second information, the target network device may determine which data packets in the data packet indicated by the second information are the data packets that failed to be received by the remote device. For example, in addition to including the sequence number of the data packet, the second information may further indicate which data packets are the data packets that failed to be received and / or which data packets are the data packets that were successfully received. In this case, the first information may indicate the data packets that failed to be received by the remote device, in other words, the second information may indicate the reception status of the remote device for the data packets via the first transmission path. For example, the second information is FMC = 3 and indicates that the bitmap is "0100 0100". Under this instruction, the second information indicates that the count of the first data packet that failed to be received is {3}, in other words, all data packets before the data packet with count {3} were successfully received, the count of the data packets that were successfully received and the data packets after the data packet is {5,9}, and the remaining data packets were not successfully received. In another example, the second information is FMS = 3 and indicates that the bitmap is "0100 0100". Under this instruction, the second information indicates that the sequence number of the first data packet that failed to be received is {3}, in other words, all data packets before the data packet with sequence number {3} were successfully received, the sequence numbers of the data packets that were successfully received and after the data packet with sequence number {3} are {5,9}, and the remaining data packets were not successfully received. The data packets that failed to be received may include data packets associated with the sequence number and / or data packets not associated with the sequence number. In another example, the second information further includes a DRB ID.For example, when the second information indicates that the DRB ID = 3 and the FMC = 3, it may indicate that it belongs to the remote device, and for the DRB with its DRB ID being 3, all data packets before the data packet with a count of {3} have been successfully received.

[0106] After receiving the second information, if the target network device determines that the data packets with sequence numbers {3, 4, 6, 7, 8, 10} and the data packets after the data packet with sequence number {10} are data packets that failed to be received by the remote device, the first information may indicate the data packet with sequence number {3} in order to indicate all data packets from the data packet with sequence number {3} to the last data packet of the remote device. Alternatively, the first information may indicate the data packet with sequence number {3} in order to indicate all data packets from the data packet with sequence number {3} to the first data packet transferred from the source network device to the target network device. In the above two processing methods of the target network device, in addition to the data packets that failed to be received by the remote device, the first information may further indicate the data packets that were successfully received by the remote device and / or the data packets that were not received by the remote device. Alternatively, the first information may indicate the data packets with sequence numbers {3, 4, 6, 7, 8, 10}. In this processing method, the first information may indicate only the data packets that failed to be received by the remote device. Alternatively, the first information may indicate the data packets with sequence numbers {3, 4, 6, 7, 8, 10} and the data packets after the data packet with sequence number {10}. In this processing method, the first information may indicate the data packets that failed to be received by the remote device and / or the data packets that were not received by the remote device.

[0107] In another example, after receiving the second information, the target network device may further determine the first information based on the second information and the data packets stored in the target network device. In this case, the first information may indicate the reception status of the data packets of the remote device and / or the reception status of the data packets of the target network device. For example, the target network device may determine whether the data packets stored in the target network device exist within the data packets indicated by the second information. If the data packets stored in the target network device exist within the data packets indicated by the second information, the first information may indicate the data packets not stored in the target network device instead of indicating the data packets stored in the target network device. The data packets stored in the target network device are, for example, the data packets received by the target network device from the source network device by data forwarding. For example, the second information indicates the first data packet within the data packets that failed to be received by the remote device in order to indicate that all data packets from the first data packet to the last data packet of the remote device have been successfully received. For example, the second information includes the sequence number {1} in order to indicate that not all data packets from the data packet with the sequence number {1} to the last data packet of the remote device have been successfully received. After receiving the second information, the target network device determines that the data packet with the sequence number {4} and the data packet after the data packet with the sequence number {4} have been received by data forwarding. In this case, the first information may indicate the data packet with the sequence number {1} in order to indicate all data packets from the data packet with the sequence number {1} to the last data packet of the remote device.Alternatively, the first information may indicate the data packet with sequence number {1} in order to indicate all data packets from the data packet with sequence number {1} to the data packet before the first data packet transferred from the source network device to the target network device. In another example, the second information includes the sequence number {1} in order to indicate that all data packets from the data packet with sequence number {1} to the last data packet of the remote device were not received normally. After receiving the second information, the target network device determines that the data packet with sequence number {1} and the data packets after the data packet with sequence number {1} are data packets that failed to be received by the remote device, and determines that the data packets transferred by the source network device of the remote device after the data packet with sequence number {4} and the data packet with sequence number {4} were received via data transfer. In this case, the first information may indicate the data packets with sequence numbers {1, 2, 3} in order to indicate all data packets from the data packet with sequence number {1} to the last data packet of the remote device. Alternatively, the first information may indicate the data packets with sequence numbers {1, 2, 3}. Alternatively, the first information may include the serial number (e.g., sequence number or count) of the data packet and a bitmap. The serial number of the data packet may indicate the sequence number or count of the first data packet that needs to be transferred, and the bitmap indicates the data transfer status of the data packets after the data packet. For example, if the data packet that needs to be transferred is the data packet with sequence numbers {1, 2, 3}, the serial number of the data packet indicated by the first information is {1}, and the bitmap is "1100 0000". In this way, it can indicate that data transfer also needs to be performed for the data packets with sequence numbers {2, 3}.Optionally, the first information may further include DRB ID information to indicate information about the data radio bearer for which data transfer needs to be performed.

[0108] S303: The source network device sends the first data packet to the target network device. Correspondingly, the target network device receives the first data packet from the source network device.

[0109] The first data packet may include one or more data packets. The first data packet is, for example, a data packet of a remote device, and the first data packet may be determined based on the first information.

[0110] In the first implementation form of the first data packet, the first data packet may include all data packets indicated by the first information. For example, if the first information indicates a data packet with a sequence number of \{1\} and data packets after the data packet with a sequence number of \{1\}, the first data packet may include all data packets starting from the data packet with a sequence number of \{1\} to the last data packet of the remote device. For example, it may include data packets with sequence numbers \{1, 2, 3, 4, 5, 6, 7\}, or it may include the data packet with a sequence number of \{1\} and the data packets after the data packet with a sequence number of \{1\}. The data packets after the data packet with a sequence number of \{1\} include data packets not associated with a sequence number. In another example, if the first information indicates data packets with sequence numbers \{1, 2, 4, 6\}, the first data packet may include the data packets with sequence numbers \{1, 2, 4, 6\}. In yet another example, if the first information indicates data packets with sequence numbers \{1, 2, 4, 6\}, the first data packet may include all data packets starting from the data packet with a sequence number of \{1\} to the last data packet of the remote device. For example, it may include data packets with sequence numbers \{1, 2, 3, 4, 5, 6, 7\}. In yet another example, if the first information indicates that the serial number of the data packet is \{1\} and the bitmap is "1100 0000", the first data packet needs to be transferred and includes data packets with sequence numbers \{1, 2, 3\} indicated by the first information.

[0111] In the implementation form 2 of the first data packet, the first data packet may include several data packets indicated by the first information. For example, if the first information indicates a data packet with a sequence number of \{1\} and a data packet after the data packet with a sequence number of \{1\}, and the source network device determines that a data packet with a sequence number of \{4\} and a data packet after the data packet with a sequence number of \{4\} are being sent to the target network device, the first data packet may include all the data packets starting from the data packet with a sequence number of \{1\} up to the data packet before the first data packet transferred from the source network device to the target network device, for example, it may include data packets with sequence numbers \{1, 2, 3\}. In another example, if the first information indicates data packets with sequence numbers \{1, 2, 4, 6\}, and the source network device determines that a data packet with a sequence number of \{6\} and a data packet after the data packet with a sequence number of \{6\} are being sent to the target network device by data transfer, the first data packet may include data packets with sequence numbers \{1, 2, 4\}. In yet another example, if the first information indicates a data packet with a sequence number of \{1\}, or indicates data packets with sequence numbers \{1, 2, 3, 4, 5, 6, 7\}, and the first information indicates data packets that failed to be received and / or data packets that were normally received in the data packets, for example, the first information indicates that data packets with sequence numbers \{1, 2, 4, 6\} are data packets that failed to be received, and / or indicates that data packets with sequence numbers \{0, 3, 5, 7\} are data packets that were normally received, the first information may include data packets with sequence numbers \{1, 2, 4, 6\}, or the first information may include data packets with sequence numbers \{1, 2, 3, 4, 5, 6, 7\}.In yet another example, when the first information indicates a data packet with a sequence number of \{1\} or data packets with sequence numbers of \{1, 2, 3, 4, 5, 6, 7\}, the first information indicates data packets that failed to be received and / or data packets that were successfully received in the data packet. For example, the first information indicates that data packets with sequence numbers of \{1, 2, 4, 6\} are data packets that failed to be received, and / or data packets with sequence numbers of \{0, 3, 5, 7\} are data packets that were successfully received. The source network device determines that a data packet with a sequence number of \{1\} has been sent to the target network device. The first information may include data packets with sequence numbers of \{2, 4, 6\}, or the first information may include data packets with sequence numbers of \{2, 3, 4, 5, 6, 7\}.

[0112] In implementation form 3 of the first data packet, the first data packet may include all data packets not indicated by the first information. This implementation form is applicable when the first information indicates data packets successfully received by the remote device. For example, when the first information indicates data packets with sequence numbers of \{0, 3, 5, 7\}, the first data packet may include data packets with sequence numbers of \{1, 2, 4, 6\}, or the first data packet may include consecutive data packets starting from the first data packet that failed to be received by the remote device. For example, the first data packet may include data packets with sequence numbers of \{1, 2, 3, 4, 5, 6, 7\}.

[0113] In implementation form 4 of the first data packet, the first data packet may include some data packets not indicated by the first information. This implementation form is applicable when the first information indicates data packets that have been successfully received by the remote device. For example, if the first information indicates data packets with sequence numbers {0, 3, 5, 7}, and the source network device determines that a data packet with a sequence number of {1} is being sent to the target network device, the first data packet may include data packets with sequence numbers {2, 4, 6}.

[0114] In implementation form 5 of the first data packet, the first data packet includes all data packets indicated by the first information. For example, the first information indicates data packets with serial numbers {1, 2, 3}. For example, the first information may use the serial number and bitmap of the data packet to execute the instruction. In this case, the first information indicates that the serial number of the data packet is {1}, the first data packet that needs to be transferred is the data packet with a serial number of {1}, the bitmap is "1100 0000", indicating that the data packets after the first data packet that need to be transferred are data packets with sequence numbers {2, 3}. Thus, the first data packet is determined to include data packets that need to be transferred and have sequence numbers {1, 2, 3} indicated by the first information.

[0115] In the implementation form 6 of the first data packet, the first data packet is determined by the source network device based on all the data packets indicated by the first information. For example, the first information is FMC = 3, indicating that the bitmap is "0100 0100". This may indicate that the reception status of the remote device is such that all the data packets before the data packet with sequence number {3} were received normally, and after the data packet with sequence number {3}, only the data packets with sequence numbers {5, 9} were received normally. Based on the fact that the data packet with sequence number {10} and the data packets after the data packet with sequence number {10} were transferred to the target network device, the first data packet may include data packets that were not received normally by the remote device and not transferred by the source network device to the target network device (indicated using the first information), that is, data packets with sequence numbers {3, 4, 6, 7, 8}. In another example, the first information is FMC = 3, indicating that the bitmap is "0100 0100". This indicates that the reception status of the remote device is such that all the data packets before the data packet with sequence number {3} were received normally, and after the data packet with sequence number {3}, only the data packets with sequence numbers {5, 9} were received normally. If the data packet is not transferred to the target network device, the first data packet may include data packets that were not received normally by the remote device, that is, data packets with sequence numbers {unordered_list_start}3, 4, 6, 7, 8, 10{unordered_list_end} and the data packets after the data packet with sequence number {10}, and the data packets after the data packet with sequence number {10} may include data packets associated with SN or data packets not associated with SN.

[0116] In implementation form 7 of the first data packet, the first data packet is determined by the source network device based on all data packets indicated by the first information. For example, the first information is FMC = 3, indicating that the bitmap is "0100 0100". This may indicate that the reception status of the remote device is such that all data packets before the data packet with sequence number {3} were received normally, and only the data packets with sequence numbers {5, 9} were received normally after the data packet with sequence number {3}. Based on the fact that the data packet with sequence number {10} and the data packets after the data packet with sequence number {10} were transferred to the target network device, the first data packet may include all data packets of the remote device starting from the first data packet that failed to be received by the remote device (indicated using the first information). For example, in addition to the data packets that failed to be received by the remote device, the first data packet may further include data packets that were received normally by the remote device and / or data packets that were not sent by the source network device to the remote device. For example, the first data packet may include data packets with sequence numbers {3, 4, 5, 6, 7, 8, 9, 10} and data packets after the data packet with sequence number {10}. In another example, the first information is FMC = 3, indicating that the bitmap is "0100 0100". This indicates that the reception status of the remote device is such that all data packets before the data packet with sequence number {3} were received normally, and only the data packets with sequence numbers {5, 9} were received normally after the data packet with sequence number {3}. If the data packet is not transferred to the target network device, the first data packet may include all data packets of the remote device starting from the first data packet that failed to be received by the remote device.For example, the first data packet may include a data packet with a sequence number of {3, 4, 5, 6, 7, 8, 9, 10} and a data packet that comes after the data packet with a sequence number of {10}. For example, in addition to the data packet that failed to be received by the remote device, the first data packet may further include a data packet that was successfully received by the remote device and / or a data packet that was not sent to the remote device by the source network device. The data packet that was not sent to the remote device by the source network device may include a data packet associated with the SN and / or a data packet not associated with the SN.

[0117] This embodiment of the present application may be related to the transmission path switching process of the remote device. Therefore, optionally, before S302, the method may further include S304 to S311.

[0118] S304: The remote device communicates with the source network device via the first relay device. For example, the remote device may send an uplink (UL) data packet to the source network device via the first relay device, and / or the remote device may receive a downlink (DL) data packet from the source network device via the first relay device. In FIG. 3, there is a circle corresponding to the first relay device on the arrow of S304, which indicates that the communication between the remote device and the source network device is transferred via the first relay device. In the accompanying drawings corresponding to the embodiments of the present application, the meaning of the circle corresponding to the device on the arrow is the same, and details will not be described below.

[0119] S305: Execute a measurement process for the remote device.

[0120] For example, a source network device transmits measurement configuration information to a remote device via a first relay device. Correspondingly, the remote device receives the measurement configuration information from the source network device via the first relay device. The measurement configuration information may be used to configure measurement information for the remote device, and the remote device may perform measurements based on the measurement information. The measurement information may include information used to perform Uu interface measurements and / or information used to perform sidelink (SL) measurements.

[0121] After performing the measurements, the remote device may obtain a measurement report. The remote device may transmit the measurement report to the source network device via the first relay device. In this case, the source network device may receive the measurement report from the remote device via the first relay device. The measurement report may include a Uu interface measurement report (e.g., including quality information of at least one cell) and / or a sidelink measurement report. The sidelink measurement report may include the results of measurements performed by the remote device on one or more other terminal devices, and may include, for example, quality information of the sidelink between the remote device and one or more other terminal devices. One or more other terminal devices may be used as candidates for the relay device of the remote device.

[0122] S306: The source network device and / or the target network device determines that the remote device executes a transmission path switch. Alternatively, the source network device or the target network device determines that the remote device switches to a second transmission path. For example, the transmission path through which the remote device is connected to the source network device via the first relay device is the first transmission path. The second transmission path is, for example, a transmission path through which the remote device is directly connected to the target network device (e.g., via the Uu interface), or a transmission path through which the remote device is connected to the target network device via the second relay device.

[0123] For example, in S306, the source network device may determine that the remote device switches to the second transmission path based on a measurement report from the remote device. After S306, the source network device may send a switch request to the target network device to request the remote device to switch to the second transmission path. After receiving the switch request from the source network device, the target network device may perform access control. If it is determined that the remote device can switch to the second transmission path, the target network device may send a switch request confirmation message to the source network device to indicate that the remote device is permitted to switch to the second transmission path. After receiving the switch request confirmation message, the source network device executes S307. Specifically, the source network device may send a switch command to the remote device via the first relay device to indicate that the remote device switches to the second transmission path. After receiving the switch command via the first relay device, the remote device may switch to the second transmission path. Optionally, the switch command is, for example, an RRC reconfiguration message (RRC reconfiguration message). In the embodiments of the present application, the "switch command" may also be referred to as a "path switch command" or the like.

[0124] Alternatively, before S306, the source network device may send a measurement report from the remote device to at least one network device, and the at least one network device may include the target network device. For example, the source network device may send a switching command to at least one network device, and the switching command may include a measurement report. The network device that receives the measurement report may determine a second transmission path based on the measurement report. For example, the second transmission path may be determined as a path where the remote device is directly connected to the network device, or an indirect path where the remote device is connected to the network device via a second relay device. For example, the at least one network device may send the determination result to the source network device, the source network device may obtain at least one determination result, and one of the at least one determination results may indicate the second transmission path determined by the corresponding network device. For example, the network device may send the determination result to the source network device via a switching request confirmation message. The source network device selects one second transmission path from at least one second transmission path. After selecting the second transmission path, the source network device may execute S307. After receiving the switching command, the remote device may switch to the second transmission path. In this case, the second transmission path may be considered to be jointly determined by the source network device and the target network device.

[0125] Alternatively, before S306, the source network device does not need to send measurement reports from the remote device to the redundant network device, but sends measurement reports to the target network device. The target network device may determine a second transmission path based on the measurement reports. For example, the second transmission path may be determined as a path where the remote device is directly connected to the network device, or an indirect path where the remote device is connected to the network device via a second relay device. The target network device may send the determination result to the source network device, and the determination result may indicate the second transmission path. For example, the target network device may send the determination result to the source network device via a switching request confirmation message. The source network device may determine the second transmission path based on the determination result. After determining the second transmission path or after receiving the determination result, the source network device may execute S307. After receiving the switching command, the remote device may switch to the second transmission path. In this case, the second transmission path may be considered to be determined by the target network device.

[0126] S308: The source network device transfers data to the target network device. Correspondingly, the target network device receives data from the source network device.

[0127] For example, the source network device may transfer a third data packet to the target network device, and the third data packet may include a data packet that the source network device does not receive feedback for (or a data packet for which the received feedback indicates a reception failure), and / or may include a data packet that has not been transmitted by the source network device to the remote device. The received feedback is, for example, RLC feedback from the first relay device. For example, the source network device may transfer a PDCP service data unit (SDU) corresponding to a PDCP protocol data unit (PDU) for which it does not receive RLC feedback from the first relay device to the target network device. The data packets that have not been transmitted by the source network device to the remote device may include data packets associated with the SN and / or data packets not associated with the SN. S308 may be considered a data forwarding process.

[0128] If the data packets not sent by the source network device to the remote device include data packets not associated with the SN, optionally, the method may further include S309: a step in which the source network device may send third information to the target network device. Correspondingly, the target network device receives the third information from the source network device. S309 may be executed before S308, may be executed after S308, or may be executed simultaneously with S308. The third information may indicate the sequence number of the first data packet not associated with the SN, for example, may indicate the SN of the first data packet not associated with the SN, or may indicate the count of the first data packet not associated with the SN. After receiving the third information, the target network device may associate the SN with each data packet not associated with the SN. The count of one data packet includes the hyper frame number (HFN) and SN of the data packet. Optionally, the third information may be a sequence number status transfer message, or the third information may be included in the sequence number status transfer message.

[0129] Alternatively, S308 may not be executed. For example, when S308 is not executed, the data transfer process in S303 may be considered a late data forwarding process. When S308 is executed, the data transfer process in S303 may be considered an auxiliary data transfer process. When S308 is not executed, in the late data forwarding process, after the remote device has successfully executed the transmission path switching, the data may be transferred to the target network device. In other words, the data transfer process may be executed in the transmission path switching completion phase. For example, in S303, late data transfer may be executed. As described in S303, the first data packet may include a data packet associated with the first information. For example, it may include some or all of the data packets indicated by the first information, or some or all of the data packets not indicated by the first information (for example, when the first information indicates a data packet that has been successfully received, the first data packet may include a data packet that has failed to be received). In addition, the first data packet may further include a third data packet, and the third data packet may include one or more data packets. For example, the third data packet includes data packets that the source network device has not received feedback for and / or data packets that have not been sent by the source network device to the remote device. This is equivalent to the data transfer being executed in S303 without the need for S308 and S309 to be executed.

[0130] Optionally, when S308 is not executed and S309 is executed, S309 may be executed before S303, after S303, or simultaneously with S303.

[0131] S310: The remote device establishes a target network device and a second transmission path based on the switching command. When S308 is executed, S310 may be executed before S308, after S308, or simultaneously with S308. Additionally, when S309 is executed, S310 may be executed before S309, after S309, or simultaneously with S309.

[0132] For example, when the second transmission path is a direct path, the remote device may execute a random access procedure to access the target network device. Alternatively, when the second transmission path is an indirect path, the remote device may establish an RRC connection with the target network device via the second relay device.

[0133] S311: The remote device sends an RRC reconfiguration complete message to the target network device. Correspondingly, the target network device receives the RRC reconfiguration complete message from the remote device. The RRC reconfiguration complete message may indicate that the remote device has successfully executed the transmission path switching, or that the remote device has been successfully handed over to the target network device. Optionally, the RRC reconfiguration complete message may include second information. In this case, the second information may further include DRB ID information.

[0134] Optionally, after S303, the method may further include S312: the step of the target network device sending a second data packet to the remote device. Correspondingly, the remote device receives the second data packet from the target network device. The second data packet may include one or more data packets, and the second data packet may be determined based on the first data packet. For example, the second data packet may include data packets that failed to be received or data packets that failed to be received by the remote device.

[0135] In an optional implementation form, the second data packet is the first data packet, that is to say, the second data packet is the same as the first data packet. For example, the second information only indicates the data packets that failed to be received by the remote device. The first information is the same as the second information. In this case, the first data packet may include the data packets that failed to be received by the remote device, and the second data packet may be the same as the first data packet. For example, the target network device may transfer the first data packet from the source network device to the remote device. Alternatively, the second information only indicates the data packets that were successfully received by the remote device. The first information is the same as the second information. The source network device may determine the data packets that failed to be received by the remote device based on the first information. In this case, the first data packet may include the data packets that failed to be received by the remote device, and the second data packet may be the same as the first data packet. For example, the target network device may transfer the first data packet from the source network device to the remote device. Alternatively, the second information may indicate the data packets that were successfully received by the remote device and the data packets that failed to be received by the remote device (for example, the second information is a PDCP status report). The first information is the same as the second information, or the first information may indicate the data packets that were successfully received by the remote device or the data packets that failed to be received by the remote device. The source network device may determine the data packets that failed to be received by the remote device based on the first information. In this case, the first data packet may include the data packets that failed to be received by the remote data device, and the second data packet may be the same as the first data packet. For example, the target network device may transfer the first data packet from the source network device to the remote device.

[0136] In another alternative implementation, the second data packet is part of the first data packet, or in other words, the second data packet may include a part of the first data packet. For example, the second information indicates only the data packets that failed to be received by the remote device. The first information is the same as the second information. In this case, the first data packet may include a plurality of consecutive data packets starting from the first data packet that failed to be received by the remote data device, and the target network device may select, from the first data packet, the data packets that failed to be received by the remote device as the second data packet. Alternatively, the second information indicates only the data packets that were successfully received by the remote device. The first information is the same as the second information. The source network device may determine, based on the first information, the data packets that failed to be received by the remote device. In this case, the first data packet may include a plurality of consecutive data packets starting from the first data packet that failed to be received by the remote device, and the target network device may select, from the first data packet, the data packets that failed to be received by the remote device as the second data packet. Alternatively, the second information may indicate the data packets that were successfully received by the remote device and the data packets that failed to be received by the remote device (e.g., the second information is a PDCP status report). The first information is the same as the second information, or the first information may indicate the data packets that were successfully received by the remote device or the data packets that failed to be received by the remote device. The source network device may determine, based on the first information, the data packets that failed to be received by the remote device.In this case, the first data packet may include a plurality of consecutive data packets starting from the first data packet that failed to be received by the remote device, and the target network device may select, as the second data packet, the data packet that failed to be received by the remote device from the first data packet.

[0137] In yet another optional implementation, the first data packet is part of the second data packet, in other words, the first data packet may include a part of the second data packet. For example, the second information indicates a data packet that failed to be received by the remote device, and the target network device determines that a part of the data packet indicated by the second information is stored in the target network device. In this case, the first information may indicate the remaining data packets other than the data packet. In this case, the first data packet may include the data packet indicated by the first information, and the target network device may use the first data packet and the currently stored data packet as the second data packet. Alternatively, the second information indicates only the data packets that were successfully received by the remote device. Based on this, the target network device determines the data packets that failed to be received by the remote device and determines that a part of the data packets indicated by the second information is stored in the target network device. In this case, the first information may indicate the remaining data packets other than the data packet. In this case, the first data packet may include the data packet indicated by the first information, and the target network device may use the first data packet and the currently stored data packet as the second data packet. Alternatively, the second information may indicate the data packets that were successfully received by the remote device and the data packets that failed to be received by the remote device (for example, the second information is a PDCP status report). Based on this, the target network device determines the data packets that failed to be received by the remote device and determines that a part of the data packets indicated by the second information is stored in the target network device. In this case, the first information may indicate the remaining data packets other than the data packet.In this case, the first data packet may include the data packet indicated by the first information, and the target network device may use the first data packet and the currently stored data packet as the second data packet.

[0138] In this embodiment of the present application, after accessing the target network device, the remote device may send second information to the target network device to indicate the data packets successfully received by the remote device and / or the data packets that failed to be received by the remote device. Based on this, the target network device may indicate the reception status of the data packet to the source network device so that the source network device can send the first data packet to the target network device. The first data packet is a data packet of the remote device. For example, the first data packet may include the data packet that failed to be received by the remote device. In this way, the target network device may send the data packet that failed to be received by the remote device to the remote device to reduce the packet loss rate.

[0139] Hereinafter, the second communication method provided in the embodiment of the present application will be described. FIG. 4 is a flowchart of the method.

[0140] S401: The source network device sends at least one data packet to the target network device. Correspondingly, the target network device receives at least one data packet from the source network device. This process is, for example, a data forwarding process.

[0141] At least one data packet may include a data packet that the source network device predicts the remote device will fail to receive. For example, when communicating with a remote device via a first relay device, the source network device may predict a data packet that the remote device has failed to receive. When the remote device performs a transmission path switch, the source network device may send predicted data packets that the remote device will fail to receive to the target network device, whereby the target network device can continue to send these data packets to the remote device after the remote device performs a transmission path switch in order to reduce the packet loss rate. In this embodiment of the present application, it is equivalent to that the source network device can determine by prediction which data packets are the data packets that the remote device has failed to receive without relying on the RLC feedback from the first relay device. Thereby, the packet loss rate caused by the fact that the first relay device cannot feedback the actual reception situation of the remote device can be reduced.

[0142] For example, the source network device may predict the transmission duration of data packets from the source network device to the remote device. When the source network device sends a switching command to the remote device to indicate that the source network device should execute a transmission path switch, the source network device may predict the data packets that have failed to be received by the remote device based on one or more of the transmission time of the data packets sent to the remote device, the transmission duration of the data packets from the source network device to the remote device, or the transmission time of the switching command. For example, before sending the switching command, the source network device separately sends data packet 1 and data packet 2 to the remote device at time point T1 and time point T2, and the source network device sends the switching command at time point T3. Time point T1 is before time point T2, and time point T2 is before time point T3. The transmission duration of the data packet is T4. For example, if the time difference between the time when the source network device sends one data packet and time point T3 is less than T4, the source network device may determine that the remote device has failed to receive the data packet. For example, if the time difference between T1 and T3 is less than T4, the source network device predicts that the remote device has failed to receive data packet 1. Alternatively, considering that the switching command needs a specific transmission duration, for example T4, to reach the remote device, if the time difference between the time when the source network device sends one data packet and time point (T3 + T4) is less than T4, the source network device may determine that the remote device has failed to receive the data packet. For example, if the time difference between T1 and time point (T3 + T4) is less than T4, the source network device predicts that the remote device will fail to receive data packet 1.

[0143] Alternatively, the source network device may predict data packets that failed to be received by the remote device in another way. The specific way is not limited.

[0144] Optionally, in addition to the data packets that the source network device predicts that the remote device will fail to receive, at least one data packet may further include data packets that have not been sent by the source network device to the remote device. The data packets that have not been sent by the source network device to the remote device may include data packets associated with the SN and / or data packets not associated with the SN.

[0145] The data transfer process in S401 may be called redundant data transfer. This is because the source network device performs the transfer based on prediction instead of performing the transfer based on the RLC feedback from the first relay device. In addition, different from dual active protocol stack (DAPS) switching, the source network device can transfer data packets not associated with the SN without waiting for the terminal handover success message sent by the target network device. Optionally, if the source network device determines that the remote device performing the path switch is a remote device connected to the source network device via an indirect path, the source network device may perform data transfer in the manner of S401. If the remote device performing the path switch is a remote device connected to the source network device via a direct path, the source network device may not need to perform data transfer in the manner of S401.

[0146] Optionally, the method may further include S402: a step in which the source network device may send fifth information to the target network device. Correspondingly, the target network device receives the fifth information from the source network device. S402 may be executed before S401, after S401, or simultaneously with S401.

[0147] For example, if the data packets not sent by the source network device to the remote device include data packets not associated with SN, the fifth information may indicate the sequence number of the first data packet not associated with SN, for example, may indicate the SN of the first data packet not associated with SN, or may indicate the count of the first data packet not associated with SN. After receiving the fifth information, the target network device may associate SN with each data packet not associated with SN. Alternatively, the fifth information may indicate the sequence number of the first data packet in the data packet transferred to the target network device, for example, may indicate the SN and HFN of the first data packet. Thus, after receiving the fifth information, the target network device may determine the sequence number of each received data packet.

[0148] Optionally, the fifth information may be a sequence number status transfer message, or the fifth information may be included in a sequence number status transfer (SN STATUS TRANSFER) message. Alternatively, the fifth message may be an early status transfer message.

[0149] This embodiment of the present application may be related to the transmission path switching process of the remote device. Therefore, optionally, before S401 (or before S402), the method may further include S403 to S406.

[0150] S403: The remote device communicates with the source network device via the first relay device. For example, the remote device may send an uplink data packet to the source network device via the first relay device, and / or the remote device may receive a downlink data packet from the source network device via the first relay device.

[0151] S404: Execute the measurement process of the remote device. For further details of S404, refer to S305 of the embodiment shown in FIG. 3.

[0152] S405: The source network device and / or the target network device determines that the remote device executes a transmission path switch. Alternatively, the source network device or the target network device determines that the remote device switches to the second transmission path. For further details of S405, refer to S306 of the embodiment shown in FIG. 3.

[0153] S406: The source network device sends a switching command to the remote device via the first relay device. Correspondingly, the remote device receives the switching command from the source network device via the first relay device. The switching command may indicate to the remote device to switch to the second transmission path.

[0154] Optionally, after receiving the switching command, the remote device may be disconnected from the first relay device.

[0155] Alternatively, the source network device may further send fourth information to the remote device. For example, the fourth information indicates the first data packet. For example, the fourth information may include the sequence number of the first data packet to indicate the first data packet. For example, the fourth information is included in the switching command and may be sent separately. The fourth information indicates the first data packet and indicates that the remote device stops communicating with the first relay device after receiving the first data packet. In this case, after receiving the fourth information, if the remote device is not currently receiving the first data packet, even if the remote device is currently receiving the switching command, the remote device may not be disconnected from the first relay device and may continue to communicate with the first relay device. The remote device may stop communicating with the first relay device until the remote device receives the first data packet. Alternatively, the fourth information indicates the first data packet and indicates that the remote device stops communicating with the first relay device after the next data packet to be delivered to the upper layer is the first data packet or a data packet after the first data packet. For example, the PDCP layer of the remote device may sort the received data packets. In the case of sorted data packets with consecutive sequence numbers, the PDCP layer may deliver the data packets to the upper layer. In the case of sorted data packets with discontinuous sequence numbers, the PDCP layer does not deliver the data packets starting from the first data packet with discontinuous sequence numbers to the upper layer and continues to wait for the received data packets that have not been received. RX_DELIV of the remote device may be used to record the sequence number of the first data packet that is of the remote device and is not delivered to the upper layer of the PDCP layer.For example, if the value of RX_DELIV is equal to 4, it indicates that the first data packet that is not delivered to the upper layer of the PDCP layer and belongs to the remote device is the first data packet, or if the value of RX_DELIV is greater than 4, it indicates that the first data packet that is not delivered to the upper layer of the PDCP layer and belongs to the remote device is a data packet after the first data packet.

[0156] Alternatively, if the remote device has received the fourth piece of information and is currently receiving the first data packet, the remote device may disconnect from the first relay device. In this case, the remote device may disconnect from the first relay device when the condition that "the first data packet is being received" is satisfied. As a result, even without feedback, the source network device can equivalently determine that the remote device has successfully received the first data packet and all data packets before the first data packet. In this way, the source network device can determine the data packets that have failed to be received by the remote device. For example, the data packets that have failed to be received by the remote device are the data packets after the first data packet. Alternatively, the source network device may not send the data packets after the first data packet to the remote device. Therefore, at least one data packet in S401 may include data packets that have not been sent by the source network device to the remote device. For example, the source network device uses the fourth piece of information to indicate that the remote device stops communicating with the first relay device after receiving a data packet with a sequence number of \{3\}, or uses the fourth piece of information to indicate that the remote device stops communicating with the first relay device when the sequence number corresponding to the first data packet delivered to the upper layer is \{4\} or a sequence number after \{4\}. In this case, at least one data packet in S401 may include a data packet with a sequence number of \{4\} and data packets after the data packet with a sequence number of \{4\}.

[0157] Optionally, the switching command may further indicate a data radio bearer (DRB) corresponding to the fourth piece of information. For example, the switching command includes the identity (ID) of the DRB corresponding to the fourth piece of information.

[0158] For example, the switching command is an RRC reconfiguration message.

[0159] Optionally, the method may further include S407 to S410.

[0160] S407: The remote device establishes a second transmission path with the target network device based on the switching command. S407 may be executed before S401, after S401, or simultaneously with S401. S407 may be executed before S402, after S402, or simultaneously with S402.

[0161] For example, when the second transmission path is a direct path, the remote device may execute a random access procedure to access the target network device. Alternatively, when the second transmission path is an indirect path, the remote device may establish an RRC connection with the target network device via the second relay device.

[0162] S408: The remote device sends an RRC reconfiguration complete message to the target network device. Correspondingly, the target network device receives the RRC reconfiguration complete message from the remote device. The RRC reconfiguration complete message may indicate that the remote device has successfully executed the transmission path switching, or that the remote device has successfully handed over to the target network device.

[0163] S409: The remote device sends the second information to the target network device. Correspondingly, the target network device receives the second information from the remote device.

[0164] Optionally, when the source network device transmits fourth information to the remote device, it is highly likely that the remote device will receive all data packets normally. In this case, S409 may not be executed, or S409 may be executed. In this case, the second information may indicate the data packets that have been normally received by the remote device, and the data packets that have been normally received by the remote device may include all the data packets received by the remote device.

[0165] For further details of this step, refer to S302 of the embodiment shown in FIG. 3.

[0166] S410: The target network device transmits a second data packet to the remote device. Correspondingly, the remote device receives the second data packet from the target network device.

[0167] The second data packet may include one or more data packets. For example, the second data packet may include the data packets that have failed to be received by the remote device. If the remote device has no data packets that have failed to be received, S410 may not be executed.

[0168] In this embodiment of the present application, the source network device transmits, based on a prediction, data packets that may have failed to be received by the remote device to the target network device. Therefore, if the remote device fails to receive the data packets, these data packets may be stored in the target network device. In this case, if the target network device determines, based on the first information, data packets that have failed to be received by the remote device, the target network device may transmit these locally stored data packets to the remote device, and there is no need to request data packets from the source network device. In this way, the process of interaction between the target network device and the source network device is reduced, the signaling overhead is reduced, and the delay in data acquisition by the remote device is reduced. Optionally, the source network device may further transmit fourth information to the remote device to indicate data packets that can be received by the remote device from the source network device. As a result, the amount of data transmitted by the source network device to the target network device can be reduced, the transmission overhead can be reduced, and the packet loss amount of the remote device can also be reduced.

[0169] The following describes a third communication method provided in an embodiment of the present application. FIG. 5 is a flowchart of the method.

[0170] S501: The source network device transmits fourth information to the remote device via the first relay device. Correspondingly, the remote device receives the fourth information from the source network device via the first relay device.

[0171] For example, the fourth piece of information indicates the first data packet. For example, the fourth piece of information may include the sequence number of the first data packet in order to indicate the first data packet. For example, the fourth piece of information may be included in a switching command and transmitted separately. In FIG. 5, for example, the fourth piece of information is included in the switching command. The fourth piece of information indicates the first data packet and indicates that the remote device stops communicating with the first relay device after receiving the first data packet, or that the remote device stops communicating with the first relay device after the next data packet to be delivered to the upper layer is the first data packet or a data packet after the first data packet.

[0172] For further details of S501, refer to S406 of the embodiment shown in FIG. 4.

[0173] S502: The source network device transmits at least one data packet to the target network device. Correspondingly, the target network device receives at least one data packet from the source network device. This process is, for example, a redundant data transfer process.

[0174] At least one data packet may include data packets not sent by the source network device to the remote device. For example, after the source network device receives a data packet with a sequence number of \{3\} using the fourth piece of information, it indicates that the remote device stops communicating with the first relay device. In this case, at least one data packet may include a data packet with a sequence number of \{4\} and a data packet after the data packet with a sequence number of \{4\}. Since the source network device uses the fourth piece of information to ensure to a certain extent that the actual reception status of the remote device's data packets is the same as the reception status considered by the source network device, the source network device does not need to send excessive data packets to the target network device. This can reduce the transmission overhead.

[0175] Optionally, the method may further include step S503: the source network device may send fifth information to the target network device. Correspondingly, the target network device receives the fifth information from the source network device. S503 may be executed before S502, after S502, or simultaneously with S502. For further details of S503, refer to S402 in the embodiment shown in FIG. 4.

[0176] This embodiment of the present application may be related to the transmission path switching process of the remote device. Therefore, optionally, before S501, the method may further include S504 to S506.

[0177] S504: The remote device communicates with the source network device via the first relay device. For example, the remote device may send an uplink data packet to the source network device via the first relay device, and / or the remote device may receive a downlink data packet from the source network device via the first relay device.

[0178] S505: Execute a measurement process for the remote device. For further details of S505, refer to S305 of the embodiment shown in FIG. 3.

[0179] S506: The source network device and / or the target network device determines that the remote device executes a transmission path switch. Alternatively, the source network device or the target network device determines that the remote device switches to the second transmission path. For further details of S506, refer to S306 of the embodiment shown in FIG. 3.

[0180] Optionally, the method further includes S507 to S510.

[0181] S507: The remote device establishes a second transmission path with the target network device based on the switch command. S507 may be executed before S502, after S502, or simultaneously with S502. S507 may be executed before S503, after S503, or simultaneously with S503.

[0182] For example, when the second transmission path is a direct path, the remote device may execute a random access procedure to access the target network device. Alternatively, when the second transmission path is an indirect path, the remote device may establish an RRC connection with the target network device via the second relay device.

[0183] S508: The remote device sends an RRC reconfiguration complete message to the target network device. Correspondingly, the target network device receives the RRC reconfiguration complete message from the remote device. The RRC reconfiguration complete message may indicate that the remote device has successfully executed the transmission path switching, or may indicate that the remote device has been successfully handed over to the target network device.

[0184] S509: The remote device sends the second information to the target network device. Correspondingly, the target network device receives the second information from the remote device.

[0185] Optionally, when the source network device sends the fourth information to the remote device, it is highly likely that the remote device will receive all data packets normally. In this case, S509 may not be executed, or S509 may be executed. In this case, the second information may indicate the data packets successfully received by the remote device, and the data packets successfully received by the remote device may include all the data packets received by the remote device.

[0186] For further details of this step, please refer to S302 in the embodiment shown in FIG. 3.

[0187] S510: The target network device sends the second data packet to the remote device. Correspondingly, the remote device receives the second data packet from the target network device.

[0188] The second data packet may include one or more data packets. For example, the second data packet may include the data packets that failed to be received by the remote device. If there are no data packets that failed to be received by the remote device, S510 may not be executed.

[0189] In this embodiment of the present application, the remote device is disconnected from the first relay device only after receiving the first data packet. In this case, the remote device may be considered to have received the first data packet and all data packets before the first data packet normally. However, the source network device transmits data packets after the first data packet to the target network device. Therefore, after the remote device executes the transmission path switching, the target network device may continue to transmit data packets to the remote device. This reduces the packet loss amount of the remote device. In addition, the source network device does not need to transmit excessive data packets to the target network device. Thereby, the transmission overhead can be reduced.

[0190] The following describes a fourth communication method provided in the embodiments of the present application. FIG. 6 is a flowchart of the method.

[0191] S601: The source network device transmits a switching command to the remote device via the first relay device. Correspondingly, the remote device receives the switching command from the source network device via the first relay device. The switching command may indicate to the remote device to switch to the second transmission path.

[0192] For example, after receiving the switching command, the remote device may be disconnected from the first relay device.

[0193] For example, the switching command is an RRC reconfiguration message.

[0194] Optionally, the switching command may further include seventh information, and the seventh information may indicate to send reception status information to the remote device. The reception status information is information regarding the reception status of data packets of the remote device. This is equivalent to the source network device triggering the remote device to send information regarding the reception status of data packets of the remote device in an explicit indication manner in order to simplify the implementation of the remote device.

[0195] Optionally, the switching command may further indicate a DRB corresponding to the seventh information. For example, the switching command includes the ID of the DRB corresponding to the seventh information.

[0196] S602: The remote device sends sixth information to the source network device via the first relay device. Correspondingly, the source network device receives the sixth information from the remote device via the first relay device.

[0197] The sixth information is, for example, information regarding the reception status of data packets of the remote device. The sixth information may indicate data packets that failed to be received by the remote device and / or data packets that were successfully received by the remote device. For example, the implementation form of the sixth information may be the same as the implementation form of the second information in the embodiment shown in FIG. 3. Therefore, for further details, refer to the description of the second information in the embodiment shown in FIG. 3.

[0198] For example, the remote device may trigger the reporting of the sixth information based on the switching command. Alternatively, the remote device may trigger the reporting of the sixth information based on the seventh information. Alternatively, after receiving the switching command, the remote device may send the sixth information via an RRC message.

[0199] In this embodiment of the present application, the remote device may notify the source network device of the actual reception status of the remote device. As a result, the source network device can determine, based on the sixth information, the data packets that have failed to be received by the remote device.

[0200] S603: The source network device transmits at least one data packet to the target network device. Correspondingly, the target network device receives at least one data packet from the source network device. This process is, for example, the data transfer process of S401 or the redundant data transfer process.

[0201] The at least one data packet may include data packets that have not been transmitted by the source network device to the remote device. For example, if the source network device determines, based on the sixth information, that the remote device has failed to receive data packets with sequence numbers {1, 2, 4, 6} and the data packet after the data packet with sequence number {6}, the at least one data packet may include data packets with sequence numbers {1, 2, 4, 6} and the data packet after the data packet with sequence number {6}. Since the source network device knows the actual reception status of the remote device, the source network device does not need to transmit excessive data packets to the target network device. Thereby, the transmission overhead can be reduced. In addition, the data packets transmitted by the source network device to the target network device also include the data packets that have failed to be received by the remote device. As a result, the packet loss amount of the remote device can be reduced.

[0202] Optionally, the method may further include step S604: the source network device may send eighth information to the target network device. Correspondingly, the target network device receives the eighth information from the source network device. S604 may be executed before S603, after S603, or simultaneously with S603. The eighth information may be the same as the fifth information in the embodiment shown in FIG. 4. Therefore, for further details of S604, reference may be made to S402 of the embodiment shown in FIG. 4.

[0203] This embodiment of the present application may be related to the transmission path switching process of the remote device. Therefore, optionally, before S601, the method may further include S605 to S607.

[0204] S605: The remote device communicates with the source network device via a first relay device. For example, the remote device may send an uplink data packet to the source network device via the first relay device, and / or the remote device may receive a downlink data packet from the source network device via the first relay device.

[0205] S606: Execute a measurement process for the remote device. For further details of S606, reference may be made to S305 of the embodiment shown in FIG. 3.

[0206] S607: The source network device and / or the target network device determines that the remote device executes transmission path switching. Alternatively, the source network device or the target network device determines that the remote device switches to a second transmission path. For further details of S607, reference may be made to S306 of the embodiment shown in FIG. 3.

[0207] Optionally, the method further includes S608 to S611.

[0208] S608: The remote device establishes a second transmission path with the target network device based on the switching command. S608 may be executed before S603, after S603, or simultaneously with S603. S608 may be executed before S604, after S604, or simultaneously with S604.

[0209] For example, when the second transmission path is a direct path, the remote device may execute a random access procedure to access the target network device. Alternatively, when the second transmission path is an indirect path, the remote device may establish an RRC connection with the target network device via the second relay device.

[0210] S609: The remote device sends an RRC reconfiguration complete message to the target network device. Correspondingly, the target network device receives the RRC reconfiguration complete message from the remote device. The RRC reconfiguration complete message may indicate that the remote device has successfully executed the transmission path switching, or that the remote device has been successfully handed over to the target network device.

[0211] S610: The remote device sends the second information to the target network device. Correspondingly, the target network device receives the second information from the remote device.

[0212] For further details of this step, please refer to S302 in the embodiment shown in FIG. 3.

[0213] S611: The target network device sends the second data packet to the remote device. Correspondingly, the remote device receives the second data packet from the target network device.

[0214] The second data packet may include one or more data packets. For example, the second data packet may include data packets that have failed to be received by the remote device.

[0215] In this embodiment of the present application, the source network device knows the actual reception status of the remote device, and thus may transfer data packets that have failed to be received by the remote device to the target network device. After the remote device executes transmission path switching, the target network device may send these data packets to the remote device, and it is not necessary to request these data packets from the source network device. Thereby, the process of interaction between the target network device and the source network device can be reduced, and the packet loss amount of the remote device can also be reduced.

[0216] The following describes a fifth communication method provided in an embodiment of the present application. FIG. 7 is a flowchart of the method.

[0217] S701: The source network device sends a first data packet to a first relay device. Correspondingly, the first relay device receives the first data packet from the source network device.

[0218] The first data packet is a data packet to be sent to the remote device, and the first relay device functions as a transfer device. One data packet has a sequence number of the PDCP layer, that is, the sequence number described in the foregoing embodiments of the present application, for example, SN or count. In addition, the data packet further has a sequence number of the radio link control (RLC) layer. For example, the PDCP SN of the first data packet is {1}, and the radio link control (RLC) SN of the first data packet is, for example, {a}.

[0219] S702: The first relay device transmits the first data packet to the remote device. Correspondingly, the remote device receives the first data packet from the first relay device.

[0220] The first relay device may provide services to multiple remote devices, and the connection between the first relay device and the source network device may be shared by multiple remote devices. Therefore, after receiving the first data packet, the first relay device may update the RLC SN of the first data packet so that the RLC SNs of the data packets of different remote devices are different. For example, the first relay device may update the RLC SN of the first data packet to {b}, and then transmit the first data packet to the PC5 RLC entity of the remote device via the PC5 RLC entity of the first relay device.

[0221] S703: The remote device transmits the first feedback information to the first relay device. Correspondingly, the first relay device receives the first feedback information from the remote device. For example, the PC5 RLC entity of the remote device may transmit the first feedback information to the PC5 RLC entity of the first relay device.

[0222] The first feedback information may indicate whether the first data packet with the RLC SN of {b} was successfully received or the reception failed. For example, the first feedback information is feedback information from the RLC layer. For example, if the first feedback information is an acknowledgement (ACK), it indicates that the first data packet was successfully received; or if the first feedback information is a negative acknowledgement (NACK), it indicates that the reception of the first data packet failed.

[0223] S704: The first relay device sends the second feedback information to the source network device based on the first feedback information. Correspondingly, the source network device receives the second feedback information from the first relay device.

[0224] The second feedback information is, for example, feedback information from the RLC layer, and the second feedback information may indicate that the first data packet with the RLC SN being {a} has been successfully received or has failed to be received. The situation indicated by the second feedback information may be consistent with the situation indicated by the first feedback information. For example, if the first feedback information indicates that the first data packet has been successfully received, the second feedback information indicates that the first data packet has been successfully received; or, if the first feedback information indicates that the first data packet has failed to be received, the second feedback information indicates that the first data packet has failed to be received.

[0225] For example, after receiving the first feedback information, if the first relay device receives a polling command from the RLC entity of the source network device, the first relay device may send the second feedback information to the source network device. The polling command may be used to trigger the first relay device to send feedback information.

[0226] Alternatively, after the first relay device receives the first feedback information, if a timer maintained by the RLC entity of the first relay device expires, the first relay device may send the second feedback information to the source network device. The timer may be, for example, a t reassembly timer. For example, if the first relay device fails to receive a data packet, the timer may expire. In this case, the first relay device may send the first feedback information to the source network device.

[0227] As described above, the second feedback information is determined based on the first feedback information. In this case, after receiving the first feedback information, the first relay device needs to send the second feedback information to the source network device. In other words, in this embodiment of the present application, it is specified that the first relay device should receive the feedback information of the remote device and then send the feedback information to the source network device based on the feedback information of the remote device. In this way, it can be ensured that the RLC feedback obtained by the source network device from the first relay device can reflect the actual reception status of the remote device.

[0228] Optionally, after S704, the remote device may execute a transmission path switching process. Details regarding the process will not be described again. Since the source network device knows the actual reception status of the remote device, in the transmission path switching process, when transferring data packets to the target network device, the source network device may transfer the data packets that failed to be received by the remote device to the target network device. In this way, after the remote device executes transmission path switching, the target network device may continue to send these data packets to the remote device. In this way, the source network device does not need to send excessive data packets to the target network device. Thereby, the transmission overhead can be reduced. In addition, the target network device does not need to request data packets from the source network device anymore. Thereby, the interaction process between the target network device and the source network device is reduced, and the packet loss amount of the remote device is also reduced.

[0229] FIG. 8 is a diagram of the structure of a communication device according to an embodiment of the present application. The communication device 800 may be a remote device or a circuit system of a remote device in the embodiment shown in any one of FIGS. 3 to 7, and is configured to implement a method corresponding to the remote device in the embodiment of the foregoing method. Alternatively, the communication device 800 may be a source network device or a circuit system of a source network device in the embodiment shown in any one of FIGS. 3 to 7, and is configured to implement a method corresponding to the source network device in the embodiment of the foregoing method. Alternatively, the communication device 800 may be a target network device or a circuit system of a target network device in the embodiment shown in any one of FIGS. 3 to 7, and is configured to implement a method corresponding to the target network device in the embodiment of the foregoing method. Alternatively, the communication device 800 may be a first relay device or a circuit system of a first relay device in the embodiment shown in any one of FIGS. 3 to 7, and is configured to implement a method corresponding to the first relay device in the embodiment of the foregoing method. For specific functions, refer to the description of the foregoing method embodiments. For example, the circuit system is a chip system.

[0230] The communication device 800 includes at least one processor 801. The processor 801 may be configured to execute internal processing of the device to implement specific control processing functions. Optionally, the processor 801 includes instructions. Optionally, the processor 801 may store data. Optionally, separate processors may be independent components, may be located at separate physical locations, or may be located in separate integrated circuits. Optionally, separate processors may be integrated into one or more processors, for example, integrated into one or more integrated circuits.

[0231] Optionally, communication device 800 includes one or more memories 803 configured to store instructions. Optionally, memory 803 may further store data. The processor and the memory may be separately located or integrated together.

[0232] Optionally, communication device 800 includes communication line 802 and at least one communication interface 804. Since memories 803, communication line 802, and communication interface 804 are all optional, in FIG. 8, memories 803, communication line 802, and communication interface 804 are all represented by dashed lines.

[0233] Optionally, communication device 800 may further include a transceiver and / or an antenna. The transceiver may be configured to transmit information to another device or receive information from another device. The transceiver may be referred to as a transceiver machine, a transceiver circuit, an input / output interface, etc., and is configured to implement the transceiver function of communication device 800 via the antenna. Optionally, the transceiver includes a transmitter and a receiver. For example, the transmitter may be configured to generate a radio frequency signal based on a baseband signal, and the receiver may be configured to convert the radio frequency signal into a baseband signal.

[0234] Processor 801 may include a general-purpose central processing unit (CPU), a microprocessor, an application specific integrated circuit (ASIC), or one or more integrated circuits configured to control the program execution of the solution of the present application.

[0235] Communication line 802 may include a path and transfer information between the aforementioned components.

[0236] The communication interface 804 is configured to communicate with another device or a communication network, such as Ethernet, a radio access network (RAN), a wireless local area network (WLAN), or a wired access network, via any device such as a transceiver.

[0237] The memory 803 may be a read-only memory (ROM) or another type of static storage device that can store static information and instructions, a random access memory (RAM) or another type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or another optical disk storage, optical disk storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), a magnetic disk storage medium or another magnetic storage device, or any other medium that can be used to carry or store program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 803 may exist independently or be connected to the processor 801 via the communication line 802. Alternatively, the memory 803 may be integrated with the processor 801.

[0238] Memory 803 is configured to store computer-executable instructions for executing the solution of the present application, and processor 801 controls the execution of the computer-executable instructions. Processor 801 is configured to execute the computer-executable instructions stored in memory 803 to implement the communication method provided in the foregoing embodiments of the present application.

[0239] Optionally, the computer-executable instructions in this embodiment of the present application may be referred to as application program code. This is not specifically limited in this embodiment of the present application.

[0240] In a specific implementation, in one embodiment, processor 801 may include one or more CPUs, for example, CPU0 and CPU1 shown in FIG. 8.

[0241] In a specific implementation, in one embodiment, communication device 800 may include a plurality of processors, for example, processor 801 and processor 805 in FIG. 8. Each of the processors may be a single-CPU processor or a multi-CPU processor. The processor in this specification may be one or more devices, circuits, and / or processing cores configured to process data (e.g., computer program instructions).

[0242] When the device shown in FIG. 8 is a chip, for example, a chip of a remote device, a chip of a source network device, a chip of a target network device, or a chip of a first relay device, the chip includes a processor 801 (which may further include a processor 8 **05**), a communication line 802, and a communication interface 804. Optionally, the chip may further include a memory 803. Specifically, the communication interface 804 may be an input interface, a pin, a circuit, etc. The memory 803 may be a register or a buffer, etc. The processor 801 and the processor 805 may be a general-purpose CPU, a microprocessor, an ASIC, or one or more integrated circuits configured to control the execution of a program of the communication method in any one of the foregoing embodiments.

[0243] In the embodiments of the present application, the device may be divided into functional modules based on the foregoing method examples. For example, each functional module may be obtained by division based on each corresponding function, or two or more functions may be integrated into one processing module. The integrated module may be implemented in the form of hardware or in the form of a software functional module. In the embodiments of the present application, it should be noted that the division of the module is only an example and is only a logical function division. In actual implementation, another division method may be used. For example, when each functional module is obtained by division based on each corresponding function, FIG. 9 shows a diagram of the device. The device 900 may be the remote device, the source network device, the target network device, or the first relay device in the foregoing method embodiments, or may be a chip in the remote device, a chip in the source network device, a chip in the target network device, or a chip in the first relay device. The device 900 includes a transmission unit 901, a processing unit 902, and a reception unit 903.

[0244] It should be understood that the apparatus 900 may be configured to implement steps performed by a remote device, a source network device, a target network device, or a first relay device in the method of the embodiments of the present application. For related features, reference may be made to the foregoing embodiments. Details are not described again herein.

[0245] Optionally, the functions / implementation processes of the transmission unit 901, the reception unit 903, and the processing unit 902 in FIG. 9 may be implemented by the processor 801 in FIG. 8 by calling computer-executable instructions stored in the memory 803. Alternatively, the function / implementation process of the processing unit 902 in FIG. 9 may be implemented by the processor 801 in FIG. 8 by calling computer-executable instructions stored in the memory 803, and the functions / implementation processes of the transmission unit 901 and the reception unit 903 in FIG. 9 may be implemented by the communication interface 804 in FIG. 8.

[0246] Optionally, when the apparatus 900 is a chip or a circuit, the functions / implementation processes of the transmission unit 901 and the reception unit 903 may alternatively be implemented using pins or circuits or the like.

[0247] This application further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program or instructions. When the computer program or instructions are executed, the methods performed by the remote device, source network device, target network device, or first relay device in the foregoing method embodiments are implemented. Thus, the functions of the foregoing embodiments may be implemented in the form of software function units and may be sold or used as independent products. Based on such understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, may also be implemented in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for instructing a computer device (which may be a personal computer, server, network device, etc.) to execute all or part of the steps of the methods described in the embodiments of this application. The storage medium includes any medium that can store program code, such as a USB flash drive, removable hard disk, ROM, RAM, magnetic disk, optical disk, etc.

[0248] This application further provides a computer program product. The computer program product includes computer program code. When the computer program code is executed on a computer, the computer is enabled to execute the method performed by the remote device, source network device, target network device, or first relay device in any one of the foregoing method embodiments.

[0249] An embodiment of this application further provides a processing device including a processor and an interface. The processor is configured to execute the method performed by the remote device, source network device, target network device, or first relay device in any one of the foregoing method embodiments.

[0250] All or part of the foregoing embodiments may be implemented by software, hardware, firmware, or any combination thereof. When software is used to implement the embodiments, all or part of the embodiments may be implemented 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 procedures or functions according to the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a dedicated computer, a computer network, or other programmable devices. The computer instructions may 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 may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired (e.g., coaxial cable, optical fiber, or digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, or microwave) manner. The computer-readable storage medium may be any available medium accessible by a computer or a data storage device incorporating one or more available media, such as a server or a data center. The available medium may be a magnetic medium (e.g., floppy disk, hard disk, or magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk (SSD)), etc.

[0251] The various exemplary logic units and circuits described in the embodiments of this application may be implemented or operated by using the design of a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or another programmable logic device, discrete gates or transistor logic, discrete hardware components, or any combination of the foregoing devices. The general-purpose processor may be a microprocessor. Optionally, the general-purpose processor may also be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented by a combination of computing devices such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors having digital signal processor cores, or any other similar configuration.

[0252] The steps of the methods or algorithms described in the embodiments of this application may be directly incorporated into hardware, software units executed by a processor, or a combination thereof. The software units may be stored in RAM, flash memory, ROM, erasable programmable read-only memory (EPROM), EEPROM, registers, hard disks, removable magnetic disks, CD-ROMs, or any other form of storage medium in the relevant art. For example, the storage medium may be connected to the processor, whereby the processor may read information from the storage medium and write information to the storage medium. Optionally, the storage medium may be integrated with the processor. The processor and the storage medium may be disposed in an ASIC, and the ASIC may be disposed in a terminal device. Optionally, the processor and the storage medium may be disposed in different parts of the terminal device.

[0253] These computer program instructions may be loaded onto a computer or another programmable data processing device, resulting in a series of operations and steps being executed on the computer or another programmable device, thereby generating a computer-implemented process. Accordingly, the instructions executed on a computer or another programmable device provide the steps for implementing a specific function in one or more processes of the flowchart and / or one or more blocks of the block diagram.

[0254] While embodiments of the present application have been described with reference to specific features and their embodiments, it is clear that various modifications and combinations can be made to the embodiments of the present application without departing from the scope of the embodiments of the present application. Correspondingly, the embodiments of the present application and the accompanying drawings are merely illustrative descriptions of the present application defined by the appended claims, and are considered to cover any or all of the modifications, variations, combinations, or equivalents of the embodiments of the present application. Obviously, those skilled in the art may make various modifications and variations to the embodiments of the present application without departing from the scope of the embodiments of the present application. Thus, the embodiments of the present application are also intended to include these modifications and variations if they are within the scope of the claims of the embodiments of the present application and the scope of equivalent technologies.

Explanation of Signs

[0255] 1 Access network device, relay device, data packet 2 Access network device, relay device, data packet 800 Communication device 801 Processor 802 Communication line 803 Memory 804 Communication interface 805 Processor 900 Device 901 Transmission unit 902 Processing unit 903 Reception unit

Claims

1. A communication method applied to a target network device, the method comprising: transmitting first information to a source network device, the first information indicating a reception status of data packets; receiving a first data packet from the source network device, the first data packet being a data packet of a remote device, the first data packet being determined based on the first information, the remote device being connected to the source network device via a first relay device before transmission path switching and being connected to the target network device after transmission path switching; A communication method comprising the above steps.

2. The method further comprises: transmitting a second data packet to the remote device, the second data packet being determined based on the first data packet. The method according to claim 1, further comprising the above step.

3. The method according to claim 1 or 2, wherein the remote device is connected to the target network device via a direct path or an indirect path after transmission path switching.

4. The method further comprises: receiving second information from the remote device, the second information indicating data packets that the remote device has failed to receive and / or data packets that the remote device has received successfully. The method according to any one of claims 1 to 3, further comprising the above step.

5. The second information is a PDCP status report, or the second information is included in an RRC reconfiguration message, the RRC reconfiguration message indicating that the remote device has been successfully handed over to the target network device. The method according to claim 4.

6. The first data packet is the second data packet, or The first data packet is part of the second data packet, and the first data packet is a data packet that has not been received by the target network device from the source network device before the target network device receives the first data packet. The second data packet further includes another part of the data packet, and the another part of the data packet is a data packet that has been received by the target network device from the source network device before the target network device receives the first data packet, or the second data packet is part of the first data packet, The method according to any one of claims 2 to 5.

7. The method is Before transmitting the first information to the source network device, receiving a third data packet from the source network device, where the third data packet includes a data packet that the source network device does not receive feedback for and / or a data packet that has not been transmitted by the source network device to the remote device, and the third data packet includes another part of the data packet, the step The method according to claim 6, further comprising.

8. The step of receiving the first data packet from the source network device is Receiving a third data packet from the source network device, where the third data packet includes a data packet that the source network device does not receive feedback for and / or a data packet that has not been transmitted by the source network device to the remote device, and the third data packet includes the first data packet, the step The method according to any one of claims 1 to 6, comprising.

9. The third data packet includes the data packet that has not been transmitted by the source network device to the remote device, and the data packet that has not been transmitted by the source network device to the remote device includes a data packet not associated with a sequence number. The method is Receiving third information from the source network device, wherein the third information indicates the sequence number of the first data packet not associated with a sequence number, step The method according to claim 7 or 8, further comprising

10. A communication method applied to a source network device, the method comprising Receiving first information from a target network device, wherein the first information indicates the reception status of data packets, step Transmitting a first data packet to the target network device, wherein the first data packet is a data packet of a remote device, the first data packet is determined based on the first information, and the remote device is connected to the source network device via a first relay device before transmission path switching and is connected to the target network device after transmission path switching, step A communication method comprising

11. The method according to claim 10, wherein the remote device is connected to the target network device via a direct path or an indirect path after transmission path switching

12. The method comprising Before receiving the first information from the target network device, transmitting a third data packet to the target network device, wherein the third data packet includes data packets for which the source network device does not receive reception feedback and / or data packets not transmitted by the source network device to the remote device, step The method according to claim 10 or 11, further comprising

13. The step of transmitting the first data packet to the target network device comprises Transmitting a third data packet to the target network device, wherein the third data packet includes data packets for which the source network device does not receive reception feedback and / or data packets not transmitted by the source network device to the remote device, and the third data packet includes the first data packet, step The method according to claim 10 or 11, comprising

14. The third data packet includes the data packets not sent by the source network device to the remote device, and the data packets not sent by the source network device to the remote device include data packets not associated with a sequence number, and the method comprises: sending third information to the target network device, the third information indicating a sequence number of a first data packet not associated with a sequence number; The method according to claim 12 or 13, further comprising.

15. The method is sending at least one data packet to a target network device, the at least one data packet including data packets that the source network device predicts the remote device will fail to receive, the remote device being connected to the source network device via a first relay device before transmission path switching and being connected to the target network device after transmission path switching; A communication method comprising.

16. The method is sending fourth information to the remote device, the fourth information indicating a first data packet and indicating that communication with the first relay device is to be stopped after the remote device receives the first data packet; The method according to claim 15, further comprising.

17. The method according to claim 16, wherein the fourth information is included in a switching command, the switching command indicating that the remote device is to perform transmission path switching.

18. The at least one data packet includes data packets not associated with a sequence number, and the method comprises: sending fifth information to the target network device, the fifth information indicating a sequence number of a first data packet not associated with a sequence number; The method according to any one of claims 15 to 17, further comprising.

19. A communication method applied to a source network device, the method comprising: A step of sending a switching command to a remote device, wherein the switching command indicates to execute a transmission path switch on the remote device, and the remote device is connected to the source network device via a first relay device before the transmission path switch and is connected to a target network device after the transmission path switch. A step of receiving sixth information from the remote device, wherein the sixth information indicates data packets that the remote device failed to receive and / or data packets that the remote device received normally. A communication method comprising the above.

20. The method according to claim 19, wherein the switching command further includes seventh information, and the seventh information indicates to send reception status information to the remote device.

21. The method further includes: A step of sending at least one data packet to the target network device, wherein the at least one data packet includes the data packet that the remote device failed to receive. The method according to claim 19 or 20, further comprising the above.

22. The method according to claim 21, wherein the at least one data packet further includes data packets not sent by the source network device to the remote device.

23. The data packets not sent by the source network device to the remote device include data packets not associated with a sequence number, and the method includes: A step of sending eighth information to the target network device, wherein the eighth information indicates the sequence number of the first data packet not associated with a sequence number. The method according to claim 22, further comprising the above.

24. A communication method applied to a remote device, the method comprising: Receiving a switching command from a source network device, wherein the switching command indicates to execute a transmission path switch for the remote device, and the remote device is connected to the source network device via a first relay device before the transmission path switch and is connected to a target network device after the transmission path switch; Sending sixth information to the source network device, wherein the sixth information indicates data packets that failed to be received by the remote device and / or data packets that were successfully received by the remote device; A communication method comprising the above.

25. The method according to claim 24, wherein the switching command further includes seventh information, and the seventh information indicates to send reception status information to the remote device.

26. A communication device comprising a processor and a memory, wherein the memory is coupled to the processor, and the processor is configured to execute the method according to any one of claims 1 to 9, or is configured to execute the method according to any one of claims 10 to 14, or is configured to execute the method according to any one of claims 15 to 18, or is configured to execute the method according to any one of claims 19 to 23, or is configured to execute the method according to claim 24 or 25.

27. A computer-readable storage medium configured to store a computer program, and when the computer program is executed on a computer, the computer is enabled to execute the method according to any one of claims 1 to 9, or the computer is enabled to execute the method according to any one of claims 10 to 14, or the computer is enabled to execute the method according to any one of claims 15 to 18, or the computer is enabled to execute the method according to any one of claims 19 to 23, or the computer is enabled to execute the method according to claim 24 or 25.

28. A chip system, wherein the chip system is A chip system comprising a processor and an interface, the processor being configured to call instructions from the interface and execute the instructions, and when executing the instructions, the processor implements the method according to any one of claims 1 to 9, or implements the method according to any one of claims 10 to 14, or implements the method according to any one of claims 15 to 18, or implements the method according to any one of claims 19 to 23, or implements the method according to claim 24 or 25. Chip system. A computer program product comprising a computer program, wherein when the computer program is executed on a computer, the computer is enabled to execute the method according to any one of claims 1 to 9, or the computer is enabled to execute the method according to any one of claims 10 to 14, or the computer is enabled to execute the method according to any one of claims 15 to 18, or the computer is enabled to execute the method according to any one of claims 19 to 23, or the computer is enabled to execute the method according to claim 24 or 25, a computer-readable storage medium. ​

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