A communication method and device

Abstract

The present application relates to the field of communication technology, and discloses a communication method and device. The method includes: a target network device of a terminal device receives N data packets and auxiliary information of a first service from a source network device, and the auxiliary information is used to indicate the transmission status of at least one data packet before the N data packets; the target network device can determine the transmission status of at least one data packet, and then improve the transmission reliability of the data packets to be sent (such as part or all of the N data packets) according to the transmission status of at least one data packet, so as to effectively avoid the interruption of the service at the application layer due to the switching of the terminal device.

Description

Technical Field

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

[0002] In the 3rd Generation Partnership Project (3GPP), the air interface indicator for ultra-reliable and low latency communication (URLLC) services is set as a user plane that guarantees a 1 millisecond (ms) latency plus a 99.999% reliability requirement.

[0003] In order to prevent accidental communication errors at the network layer from having a significant impact on the application layer, the application layer of the URLLC service can set a survival time. The survival time means that if the application layer does not receive a data packet within the time range in which the data packet is expected to arrive, the survival time timer will be started. If an expected application layer data packet arrives during the timer, the timer will stop. If the timer runs until it times out, that is, no expected application layer data packet arrives during the period when the survival timer is running, the application layer will be interrupted, which may affect the service. Therefore, how to avoid interruptions in the service of terminal equipment at the application layer still requires further research. Summary of the invention

[0004] The present application provides a communication method and device to facilitate avoiding service interruption at the application layer.

[0005] In a first aspect, an embodiment of the present application provides a communication method, which can be applicable to a first communication device. The first communication device can be a target network device of a terminal device or a chip in the target network device. Taking the method being applicable to a target network device of a terminal device as an example, in the method, the target network device can receive N data packets and auxiliary information of a first service from a source network device of the terminal device, the auxiliary information being used to indicate the transmission status of at least one data packet before the N data packets; and, based on the auxiliary information, determining the transmission status of the at least one data packet; N is a positive integer.

[0006] By adopting the above scheme, auxiliary information is sent from the source network device to the target network device, so that the target network device can obtain the transmission status of at least one downlink data packet in time, and then the target network device can determine whether to improve the transmission reliability of the data packets to be sent (such as part or all of N data packets), effectively avoiding the problem of service interruption at the application layer due to the target network device being unable to obtain the transmission status of at least one downlink data packet in time due to the switching of the terminal device.

[0007] In one possible design, the auxiliary information includes an identifier of a data packet that was not successfully transmitted before N data packets; or, the auxiliary information includes an identifier of a first data packet that was not successfully transmitted before N data packets, and transmission status information of M data packets after the first data packet that was not successfully transmitted, and the last data packet of the M data packets is adjacent to the first data packet of the N data packets; M is a positive integer.

[0008] In a possible design, the auxiliary information is also used to indicate the correspondence between the data packet and the transmission cycle.

[0009] By adopting this solution, the target network device can determine the corresponding relationship between the data packet and the transmission cycle according to the auxiliary information, thereby facilitating the determination of the number of consecutive transmission cycles in which the transmission is not successful.

[0010] In one possible design, the auxiliary information includes an identifier of a data packet included in at least one transmission cycle; or, the auxiliary information includes an identifier of the first data packet or the last data packet included in each transmission cycle in at least one transmission cycle, and the number of data packets or the amount of data included in each transmission cycle.

[0011] In one possible design, the method further includes: receiving data information that is allowed to be unsuccessfully transmitted from a source network device, where the data information that is allowed to be unsuccessfully transmitted is determined based on a lifetime of the first service.

[0012] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0013] In the second aspect, an embodiment of the present application provides a communication method, which can be applicable to a second communication device. The second communication device can be a source network device of a terminal device or a chip in the source network device. Taking the method being applicable to the source network device of a terminal device as an example, in the method, the source network device determines auxiliary information and sends N data packets and auxiliary information of a first service to a target network device of the terminal device; wherein the auxiliary information is used to indicate the transmission status of at least one data packet before the N data packets; N is a positive integer.

[0014] In one possible design, the auxiliary information includes an identifier of a data packet that was not successfully transmitted before N data packets; or, the auxiliary information includes an identifier of a first data packet that was not successfully transmitted before N data packets, and transmission status information of M data packets after the first data packet that was not successfully transmitted, and the last data packet of the M data packets is adjacent to the first data packet of the N data packets; M is a positive integer.

[0015] In a possible design, the auxiliary information is also used to indicate the correspondence between the data packet and the transmission cycle.

[0016] In one possible design, the auxiliary information includes an identifier of a data packet included in at least one transmission cycle; or, the auxiliary information includes an identifier of the first data packet or the last data packet included in each transmission cycle in at least one transmission cycle, and the number of data packets or the amount of data included in each transmission cycle.

[0017] In one possible design, the method further includes: sending data information that is allowed to have not been successfully transmitted to the target network device, where the data information that is allowed to have not been successfully transmitted is determined based on the lifetime of the first service.

[0018] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0019] It should be noted that the method provided in the above-mentioned second aspect corresponds to the method provided in the first aspect, and the beneficial effects of the relevant technical features in the method provided in the second aspect can be found in the description of the first aspect and will not be repeated here.

[0020] In a third aspect, an embodiment of the present application provides a communication method, which can be applicable to a first communication device. The first communication device can be a target network device of a terminal device or a chip in the target network device. Taking the method being applicable to a target network device of a terminal device as an example, in the method, the target network device receives N data packets and auxiliary information of a first service from a source network device of the terminal device, the auxiliary information being used to indicate that P data packets are not allowed to fail in transmission; and based on the auxiliary information, determining that P data packets are not allowed to fail in transmission; N and P are positive integers.

[0021] By adopting this solution, after the target network device determines that P data packets are not allowed to fail in transmission, the transmission reliability of the P downlink data packets can be improved to avoid the transmission failure of the P downlink data packets, thereby avoiding the interruption of the service at the application layer. In other words, the source network device can determine the data packets that are not allowed to fail in transmission, and then indicate it to the target network device, so that the target network device can directly learn the data packets that are not allowed to fail in transmission in a timely manner based on the auxiliary information, thereby effectively saving the processing burden of the target network device.

[0022] In one possible design, the auxiliary information includes identifiers of P data packets.

[0023] In one possible design, the method further includes: receiving data information that is allowed to be unsuccessfully transmitted from a source network device, where the data information that is allowed to be unsuccessfully transmitted is determined based on a lifetime of the first service.

[0024] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0025] In a fourth aspect, an embodiment of the present application provides a communication method, which can be applicable to a second communication device. The second communication device can be a source network device of a terminal device or a chip in the source network device. Taking the method being applicable to a source network device of a terminal device as an example, in the method, the source network device determines auxiliary information and sends N data packets and auxiliary information of a first service to a target network device of the terminal device; wherein the auxiliary information is used to indicate that transmission failure is not allowed for P data packets; N and P are positive integers.

[0026] In one possible design, the auxiliary information includes identifiers of P data packets.

[0027] In one possible design, the method further includes: sending data information that is allowed to have not been successfully transmitted to the target network device, where the data information that is allowed to have not been successfully transmitted is determined based on the lifetime of the first service.

[0028] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0029] It should be noted that the method provided in the fourth aspect corresponds to the method provided in the third aspect, and the beneficial effects of the relevant technical features in the method provided in the fourth aspect can be found in the description of the third aspect and will not be repeated here.

[0030] In a fifth aspect, an embodiment of the present application provides a communication method, which can be applicable to a first communication device. The first communication device can be a target network device of a terminal device or a chip in the target network device. Taking the method being applicable to a target network device of a terminal device as an example, in the method, the target network device receives N data packets and auxiliary information of a first service from a source network device of the terminal device, where the auxiliary information is used to indicate the state of a lifetime timer of the first service; and, based on the auxiliary information, determining the state of the lifetime timer; N is a positive integer.

[0031] By adopting the above scheme, auxiliary information is sent from the source network device to the target network device, so that the target network device can determine whether to improve the transmission reliability of the data packet to be sent according to the state of the lifetime timer, thereby effectively avoiding the problem of service interruption at the application layer due to terminal device switching.

[0032] In one possible design, the auxiliary information includes at least one of the following: status information of the lifetime timer; time information when the data packet that triggers the lifetime timer arrives at the source network device; and an identifier of the data packet that triggers the lifetime timer.

[0033] In one possible design, the method further includes: receiving data information that is allowed to be unsuccessfully transmitted from a source network device, where the data information that is allowed to be unsuccessfully transmitted is determined based on a lifetime of the first service.

[0034] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0035] In the sixth aspect, an embodiment of the present application provides a communication method, which can be applicable to a second communication device. The second communication device can be a source network device of a terminal device or a chip in the source network device. Taking the method being applicable to the source network device of a terminal device as an example, in the method, the source network device determines auxiliary information and sends N data packets and auxiliary information of a first service to a target network device of the terminal device; wherein the auxiliary information is used to indicate the status of a lifetime timer of the first service; and N is a positive integer.

[0036] In one possible design, the auxiliary information includes at least one of the following: status information of the lifetime timer; time information when the data packet that triggers the lifetime timer arrives at the source network device; and an identifier of the data packet that triggers the lifetime timer.

[0037] In one possible design, the method further includes: sending data information that is allowed to have not been successfully transmitted to the target network device, where the data information that is allowed to have not been successfully transmitted is determined based on the lifetime of the first service.

[0038] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0039] It should be noted that the method provided in the sixth aspect corresponds to the method provided in the fifth aspect, and the beneficial effects of the relevant technical features in the method provided in the sixth aspect can be found in the description of the fifth aspect and will not be repeated here.

[0040] In the seventh aspect, an embodiment of the present application provides a communication method, which can be applied to a first communication device. The first communication device can be a target network device of a terminal device or a chip in the target network device. Taking the method being applied to a target network device of a terminal device as an example, in the method, the target network device receives N data packets and auxiliary information of a first service from a source network device of the terminal device, and the auxiliary information is used to indicate the number of consecutive unsuccessful transmission data packets or the number of consecutive unsuccessful transmission cycles; wherein the last data packet among the consecutive unsuccessful transmission data packets is adjacent to the first data packet among the N data packets, and the data packets included in the next adjacent transmission cycle of the consecutive unsuccessful transmission cycle belong to the N data packets; and, based on the auxiliary information, the number of consecutive unsuccessful transmission data packets or the number of consecutive unsuccessful transmission cycles is determined; N is a positive integer.

[0041] By adopting the above scheme, auxiliary information is sent from the source network device to the target network device, so that the target network device can determine whether to improve the transmission reliability of the data packet to be sent, thereby effectively avoiding the problem of service interruption at the application layer due to terminal device switching.

[0042] In one possible design, the method further includes: receiving data information that is allowed to be unsuccessfully transmitted from a source network device, where the data information that is allowed to be unsuccessfully transmitted is determined based on a lifetime of the first service.

[0043] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0044] In the eighth aspect, an embodiment of the present application provides a communication method, which can be applicable to a second communication device. The second communication device can be a source network device of a terminal device or a chip in the source network device. Taking the method being applicable to the source network device of a terminal device as an example, in the method, the source network device determines auxiliary information and sends N data packets and auxiliary information of a first service to a target network device of the terminal device; wherein the auxiliary information is used to indicate the number of consecutive unsuccessful transmissions or the number of consecutive unsuccessful transmission cycles; wherein the last data packet of consecutive unsuccessful transmissions is adjacent to the first data packet of the N data packets, and the last data packet in the last transmission cycle of a consecutive unsuccessful transmission is adjacent to the first data packet of the N data packets.

[0045] In one possible design, the method further includes: sending data information that is allowed to have not been successfully transmitted to the target network device, where the data information that is allowed to have not been successfully transmitted is determined based on the lifetime of the first service.

[0046] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0047] It should be noted that the method provided in the above-mentioned eighth aspect corresponds to the method provided in the seventh aspect, and the beneficial effects of the relevant technical features in the method provided in the eighth aspect can be found in the description of the seventh aspect and will not be repeated here.

[0048] In a ninth aspect, the present application provides a communication device, which may be a target network device of a terminal device or a chip in a target network device. The communication device has the function of implementing the first aspect, the third aspect, the fifth aspect or the seventh aspect, for example, the communication device includes a module or unit or means corresponding to the steps involved in the first aspect, the third aspect, the fifth aspect or the seventh aspect, and the function or unit or means may be implemented by software, or by hardware, or by hardware executing the corresponding software implementation.

[0049] In one possible design, the communication device includes a processing unit and a communication unit, wherein the communication unit can be used to send and receive signals to achieve communication between the communication device and other devices, for example, the communication unit is used to receive configuration information from a network device; the processing unit can be used to perform some internal operations of the communication device. The functions performed by the processing unit and the communication unit can correspond to the steps involved in the first, third, fifth or seventh aspects described above.

[0050] In one possible design, the communication device includes a processor and may also include a transceiver, the transceiver is used to send and receive signals, and the processor executes program instructions to complete the method in any possible design or implementation of the first aspect, the third aspect, the fifth aspect or the seventh aspect. Among them, the communication device may also include one or more memories, and the memory is used to couple with the processor. The one or more memories may be integrated with the processor or may be set separately from the processor, which is not limited in this application. The memory may store the necessary computer programs or instructions for implementing the functions involved in the first aspect, the third aspect, the fifth aspect or the seventh aspect. The processor may execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the first aspect, the third aspect, the fifth aspect or the seventh aspect.

[0051] In one possible design, the communication device includes a processor and a memory, and the memory can store necessary computer programs or instructions for implementing the functions involved in the first aspect, the third aspect, the fifth aspect, or the seventh aspect. The processor can execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the first aspect, the third aspect, the fifth aspect, or the seventh aspect.

[0052] In one possible design, the communication device includes at least one processor and an interface circuit, wherein at least one processor is used to communicate with other devices through the interface circuit and execute the method in any possible design or implementation of the first aspect, third aspect, fifth aspect or seventh aspect above.

[0053] In a tenth aspect, the present application provides a communication device, which may be a source network device of a terminal device or a chip in a source network device. The communication device has the function of implementing the second aspect, the fourth aspect, the sixth aspect or the eighth aspect, for example, the communication device includes a module or unit or means corresponding to the steps involved in the second aspect, the fourth aspect, the sixth aspect or the eighth aspect, and the function or unit or means may be implemented by software, or by hardware, or by hardware executing the corresponding software implementation.

[0054] In a possible design, the communication device includes a processing unit and a communication unit, wherein the communication unit can be used to send and receive signals to achieve communication between the communication device and other devices, for example, the communication unit is used to receive configuration information from a network device; the processing unit can be used to perform some internal operations of the communication device. The functions performed by the processing unit and the communication unit can correspond to the steps involved in the second aspect, the fourth aspect, the sixth aspect, or the eighth aspect.

[0055] In one possible design, the communication device includes a processor and may also include a transceiver, the transceiver is used to send and receive signals, and the processor executes program instructions to complete the method in any possible design or implementation of the second aspect, the fourth aspect, the sixth aspect or the eighth aspect. Among them, the communication device may also include one or more memories, and the memory is used to couple with the processor. The one or more memories may be integrated with the processor or may be separated from the processor, which is not limited in this application. The memory may store the necessary computer programs or instructions for implementing the functions involved in the second aspect, the fourth aspect, the sixth aspect or the eighth aspect. The processor may execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the second aspect, the fourth aspect, the sixth aspect or the eighth aspect.

[0056] In one possible design, the communication device includes a processor and a memory, and the memory can store necessary computer programs or instructions for implementing the functions involved in the second aspect, the fourth aspect, the sixth aspect, or the eighth aspect. The processor can execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the second aspect, the fourth aspect, the sixth aspect, or the eighth aspect.

[0057] In one possible design, the communication device includes at least one processor and an interface circuit, wherein at least one processor is used to communicate with other devices through the interface circuit and execute the method in any possible design or implementation of the second, fourth, sixth or eighth aspect above.

[0058] In an eleventh aspect, the present application provides a communication system, the communication system comprising a first network device and a second network device, wherein the first network device is used to execute the method in any possible design of the first aspect, the third aspect, the fifth aspect, or the seventh aspect; the second network device is used to execute the method in any possible design of the second aspect, the fourth aspect, the sixth aspect, or the eighth aspect. In an example, the communication system may also include a terminal device, the first network device may be a source network device of the terminal device, and the second network device may be a target network device of the terminal device.

[0059] In the twelfth aspect, the present application provides a computer-readable storage medium, in which computer-readable instructions are stored. When a computer reads and executes the computer-readable instructions, the computer executes a method in any possible design of the first to eighth aspects above.

[0060] In a thirteenth aspect, the present application provides a computer program product. When a computer reads and executes the computer program product, the computer executes the method in any possible design of the first to eighth aspects above.

[0061] In a fourteenth aspect, the present application provides a chip, comprising a processor, wherein the processor is coupled to a memory and is used to read and execute a software program stored in the memory to implement a method in any possible design of the first to eighth aspects above. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A schematic diagram of a network architecture applicable to an embodiment of the present application;

[0063] Figure 2a An example diagram of the protocol layer structure between a terminal device and a network device provided in an embodiment of the present application;

[0064] Figure 2b A schematic diagram of a CU-DU separation architecture provided in an embodiment of the present application;

[0065] Figure 2c A schematic diagram of another CU-DU separation architecture provided in an embodiment of the present application;

[0066] Figure 2d A schematic diagram of an air interface protocol stack distribution provided in an embodiment of the present application;

[0067] Figure 3a An example of a service interruption at the application layer provided in an embodiment of the present application;

[0068] Figure 3b Another example of a service interruption at the application layer provided in an embodiment of the present application;

[0069] Figure 4 A schematic diagram of a switching process provided in an embodiment of the present application;

[0070] Figure 5 A flow chart corresponding to the communication method provided in Example 1 of the present application;

[0071] Figure 6 A schematic diagram of multiple downlink data packets provided in an embodiment of the present application;

[0072] Figure 7 A flow chart corresponding to the communication method provided in Embodiment 2 of the present application;

[0073] Figure 8 A flow chart corresponding to the communication method provided in Embodiment 3 of the present application;

[0074] Fig. 9 A flow chart corresponding to the communication method provided in Embodiment 4 of the present application;

[0075] Fig.10 A possible exemplary block diagram of the device involved in the embodiments of the present application;

[0076] Fig.11 A schematic diagram of the structure of a network device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0077] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0078] Figure 1 Schematic diagram of a network architecture applicable to the embodiment of the present application. Figure 1 As shown, the terminal device can access the wireless network to obtain services of the external network (such as a data network (DN)) through the wireless network, or communicate with other devices through the wireless network, such as communicating with other terminal devices. The wireless network includes a radio access network (RAN) and a core network (CN), wherein the RAN is used to access the terminal device to the wireless network, and the CN is used to manage the terminal device and provide a gateway for communicating with the DN.

[0079] The following are Figure 1 The terminal equipment, RAN, CN and DN involved are explained in detail.

[0080] 1. Terminal equipment

[0081] The terminal device includes a device that provides voice and / or data connectivity to the user, for example, it may include a handheld device with wireless connection function, or a processing device connected to a wireless modem. The terminal device can communicate with the core network via a radio access network (RAN) and exchange voice and / or data with the RAN. The terminal device may include user equipment (UE), wireless terminal equipment, mobile terminal equipment, device-to-device (D2D) terminal equipment, vehicle to everything (V2X) terminal equipment, machine-to-machine / machine-type communications (M2M / MTC) terminal equipment, Internet of Things (IoT) terminal equipment, subscriber unit, subscriber station, mobile station, remote station, access point (AP), remote terminal, access terminal, user terminal, user agent, or user equipment, etc. For example, it may include a mobile phone (or "cellular" phone), a computer with a mobile terminal device, a portable, pocket-sized, handheld, or computer-built-in mobile device, etc. For example, personal communication service (PCS) phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDA), etc. It also includes limited devices, such as devices with low power consumption, or devices with limited storage capacity, or devices with limited computing power, etc. For example, it includes information sensing devices such as barcodes, radio frequency identification (RFID), sensors, global positioning systems (GPS), laser scanners, etc.

[0082] 2. RAN

[0083] The RAN may include one or more RAN devices, and the interface between the RAN device and the terminal device may be a Uu interface (or air interface). Of course, in future communications, the names of these interfaces may remain unchanged, or may be replaced by other names, which is not limited in this application.

[0084] RAN equipment is a node or device that connects a terminal device to a wireless network. RAN equipment can also be called network equipment or base station. RAN equipment includes, but is not limited to: generation NodeB (gNB), evolved node B (eNB), radio network controller (RNC), node B (NB), base station controller (BSC), base transceiver station (BTS), home evolved nodeB (HeNB) or home node B (HNB), baseband unit (BBU), transmitting and receiving point (TRP), transmitting point (TP), mobile switching center, etc. in 5G communication system.

[0085] (1) Protocol layer structure

[0086] The communication between the RAN device and the terminal device follows a certain protocol layer structure. For example, the control plane protocol layer structure may include a radio resource control (RRC) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a media access control (MAC) layer and a physical layer; the user plane protocol layer structure may include a PDCP layer, an RLC layer, a MAC layer and a physical layer. In a possible implementation, a service data adaptation protocol (SDAP) layer may also be included above the PDCP layer.

[0087] Taking data transmission between a network device and a terminal device as an example, data transmission needs to pass through the user plane protocol layer, such as the SDAP layer, PDCP layer, RLC layer, MAC layer, and physical layer, wherein the SDAP layer, PDCP layer, RLC layer, MAC layer, and physical layer can also be collectively referred to as the access layer. Exemplarily, data is transmitted between a network device and a terminal device by establishing at least one data radio bearer (DRB), and each DRB can correspond to a set of functional entities, such as a PDCP layer entity, at least one RLC layer entity corresponding to the PDCP layer entity, at least one MAC layer entity corresponding to at least one RLC layer entity, and at least one physical layer entity corresponding to at least one MAC layer entity. It should be noted that signaling can also be transmitted between a network device and a terminal device by establishing at least one signaling radio bearer (SRB), and DRBs and SRBs can be collectively referred to as radio bearers (RBs).

[0088] Take the following data transmission as an example: Figure 2a Figure 1 is a schematic diagram of downlink data transmission between layers. Figure 2a The downward arrow in the figure indicates data transmission, and the upward arrow indicates data reception. After the SDAP layer entity obtains data from the upper layer, it can map the data to the PDCP layer entity of the corresponding DRB according to the data's QoS flow indicator (QFI). The PDCP layer entity can transmit the data to at least one RLC layer entity corresponding to the PDCP layer entity, which is then transmitted by at least one RLC layer entity to the corresponding MAC layer entity. The MAC layer entity then generates a transport block, which is then wirelessly transmitted through the corresponding physical layer entity. Data is encapsulated in each layer accordingly. The data received by a layer from the upper layer of the layer is regarded as the service data unit (SDU) of the layer. After layer encapsulation, it becomes a protocol data unit (PDU) and is then passed to the next layer. For example, the data received by the PDCP layer entity from the upper layer is called PDCP SDU, and the data sent by the PDCP layer entity to the lower layer is called PDCP PDU; the data received by the RLC layer entity from the upper layer is called RLC SDU, and the data sent by the RLC layer entity to the lower layer is called RLC PDU. Among them, data can be transmitted between different layers through corresponding channels. For example, data can be transmitted between the RLC layer entity and the MAC layer entity through a logical channel (logical channel, LCH), and data can be transmitted between the MAC layer entity and the physical layer entity through a transport channel (transport channel).

[0089] For example, according to Figure 2a It can also be seen that the terminal device also has an application layer and a non-access layer; the application layer can be used to provide services to the applications installed in the terminal device, for example, the downlink data received by the terminal device can be transmitted from the physical layer to the application layer in sequence, and then provided to the application by the application layer; for another example, the application layer can obtain the data generated by the application, and transmit the data to the physical layer in sequence, and send it to other communication devices. The non-access layer can be used to forward user data, such as forwarding the uplink data received from the application layer to the SDAP layer or forwarding the downlink data received from the SDAP layer to the application layer.

[0090] (2)CU and DU

[0091] In an embodiment of the present application, the RAN device may include one or more centralized units (CU) and one or more distributed units (DU), and multiple DUs may be centrally controlled by one CU. As an example, the interface between the CU and the DU may be referred to as an F1 interface, wherein the control plane (CP) interface may be F1-C and the user plane (UP) interface may be F1-U. The CU and DU may be divided according to the protocol layer of the wireless network: for example Figure 2b As shown, the functions of the PDCP layer and the protocol layers above it are set in the CU, and the functions of the protocol layers below the PDCP layer (such as the RLC layer and the MAC layer, etc.) are set in the DU.

[0092] It can be understood that the above-mentioned division of the processing functions of CU and DU according to the protocol layer is only an example, and it can also be divided in other ways, such as the functions of the protocol layers above the PDCP layer are set in the CU, and the functions of the protocol layers below the PDCP layer are set in the DU. For example, the CU or DU can be divided into functions with more protocol layers, and the CU or DU can also be divided into partial processing functions with protocol layers. In one design, some functions of the RLC layer and the functions of the protocol layers above the RLC layer are set in the CU, and the remaining functions of the RLC layer and the functions of the protocol layers below the RLC layer are set in the DU. In another design, the functions of the CU or DU can also be divided according to the service type or other system requirements, for example, according to the delay, the functions that need to meet the delay requirements for processing time are set in the DU, and the functions that do not need to meet the delay requirements are set in the CU. In another design, the CU may also have one or more functions of the core network. Exemplarily, the CU can be set on the network side for centralized management; the DU can have multiple radio frequency functions, or the radio frequency functions can be set remotely. The embodiments of the present application are not limited to this.

[0093] For example, the functions of a CU may be implemented by one entity, or may be implemented by different entities. Figure 2c As shown, the functions of the CU can be further divided, that is, the control plane and the user plane are separated and implemented through different entities, namely the control plane CU entity (i.e., CU-CP entity) and the user plane CU entity (i.e., CU-UP entity). The CU-CP entity and the CU-UP entity can be coupled with the DU to jointly complete the functions of the RAN device. The interface between the CU-CP entity and the CU-UP entity can be an E1 interface, the interface between the CU-CP entity and the DU can be an F1-C interface, and the interface between the CU-UP entity and the DU can be an F1-U interface. Among them, one DU and one CU-UP can be connected to one CU-CP. Under the control of the same CU-CP, one DU can be connected to multiple CU-UPs, and one CU-UP can be connected to multiple DUs.

[0094] based on Figure 2c , Figure 2d Figure 1 is a schematic diagram of the air interface protocol stack distribution. Figure 2d As shown, for both the user plane and the control plane, the air interface protocol stack can be RLC, MAC, PHY in DU, and PDCP and above protocol layers in CU.

[0095] It should be noted that: Figure 2b to Figure 2d In the illustrated architecture, the signaling generated by the CU can be sent to the terminal device through the DU, or the signaling generated by the terminal device can be sent to the CU through the DU. The DU may not parse the signaling but directly encapsulate it through the protocol layer and transparently transmit it to the terminal device or CU. In the following embodiments, if the transmission of such signaling between the DU and the terminal device is involved, then the sending or receiving of the signaling by the DU includes this scenario. For example, the signaling of the RRC or PDCP layer will eventually be processed into physical layer signaling and sent to the terminal device, or converted from the received physical layer signaling. Under this architecture, the signaling of the RRC or PDCP layer can also be considered to be sent by the DU, or by the DU and the radio frequency device.

[0096] 3. CN

[0097] CN may include one or more CN devices. Taking the 5G communication system as an example, CN may include access and mobility management function (AMF) network elements, session management function (SMF) network elements, user plane function (UPF) network elements, policy control function (PCF) network elements, unified data management (UDM) network elements, application function (AF) network elements, etc.

[0098] In addition, although not shown, the CN may also include other possible network elements, such as a network exposure function (NEF) and a network element unified data repository (UDR) network element.

[0099] 4.DN

[0100] DN, also known as packet data network (PDN), is a network outside the operator network. The operator network can access multiple DNs. Application servers corresponding to various services can be deployed in the DN to provide a variety of possible services for terminal devices. Among them, the application server can be set with an application layer equivalent to the application layer of the terminal device.

[0101] Figure 1 Among them, Npcf, Nudm, Naf, Namf, Nsmf, N1, N2, N3, N4, and N6 are interface serial numbers. The meanings of these interface serial numbers can be found in the definitions in the relevant standard protocols and are not limited here.

[0102] Understandably, Figure 1 The 5G communication system is used as an example for illustration, and the solution in the embodiment of the present application can also be applied to other possible communication systems, such as the future sixth generation (the 6th generation, 6G) communication system. The above-mentioned network elements or functions can be network elements in hardware devices, or software functions running on dedicated hardware, or virtualized functions instantiated on a platform (for example, a cloud platform). Optionally, the above-mentioned network elements or functions can be implemented by one device, or by multiple devices together, or can be a functional module in a device, and the embodiments of the present application do not specifically limit this.

[0103] based on Figure 1 The communication system shown in the figure, the relevant technical features involved in the embodiments of the present application are explained below. It should be noted that these explanations are to make the embodiments of the present application easier to understand, and should not be regarded as limiting the scope of protection required by the present application.

[0104] 1. RLC layer mode

[0105] As described above, the RLC layer is located above the MAC layer. According to different service types, the RLC layer includes three modes, namely transparent mode (TM), unacknowledged mode (UM) and acknowledged mode (AM).

[0106] If the mode of the RLC layer is TM, the RLC layer entity does not segment and concatenate the SDU delivered to the RLC layer entity, and only provides a transparent transmission function of the data.

[0107] If the RLC layer entity mode is UM, after the RLC layer entity sends the RLC PDU, it does not need the confirmation of the peer entity and will not retransmit it. In other words, after a data packet is transmitted by the UM RLC layer entity, the transmission is considered to be completed. Even if the data packet is lost during air interface transmission, the RLC layer entity will not retransmit it. UM can usually be used for services with high service latency requirements but general reliability requirements. For example, the data transmitted in UM mode can be non-critical signaling such as periodically reported measurement reports, periodically transmitted service data, etc.

[0108] If the mode of the RLC layer entity is AM, the RLC layer entity can use the automatic repeat request (ARQ) mechanism to ensure lossless transmission of data; the basic idea of ​​ARQ is that the data receiving side (referred to as the receiving side) can send an RLC status report (RLC status report) to the data sending side (referred to as the sending side) to indicate which data packets are received successfully and which data packets fail to be received. The sending side can retransmit the data packets that failed to be transmitted based on the RLC status report. AM can usually be used for services that require high service reliability, which need to avoid data transmission loss as much as possible.

[0109] Since the data transmitted uplink or downlink in the embodiment of the present application may be a service data packet transmitted periodically, the following description will be made by taking the mode adopted by the uplink transmission or downlink transmission as UM as an example. For example, taking downlink transmission as an example, when the UM mode is adopted, the network device sends data packet 1 to the terminal device, and even if the transmission of data packet 1 fails, the network device may no longer retransmit data packet 1.

[0110] 2. Survival time

[0111] 5G communication systems can support a variety of possible services, such as URLLC services. For URLLC services, in order to avoid the accidental communication errors at the network layer from having a greater impact on the application layer, the application layer of the URLLC service can set a lifetime. The lifetime means that if the application layer does not receive a data packet within the time range when the data packet is expected to arrive, the lifetime timer will be started. If an expected application layer data packet arrives during the timer, the timer will stop; if the timer runs until it times out, that is, no expected application layer data packet arrives during the period when the lifetime timer is running, the application layer will be interrupted.

[0112] For services that periodically generate data packets, in one example, the lifetime can be defined as the number of consecutive data packets that have not been successfully transmitted (for example, a). If the number of consecutive data packets that have not been successfully transmitted is greater than or equal to a, the service will be interrupted at the application layer. For example, see Figure 3a As shown, one data packet can be transmitted in one transmission cycle, and a is 2, that is, when two consecutive data packets are not transmitted successfully, the service is interrupted at the application layer.

[0113] For this example, in order to avoid service interruption at the application layer, a possible implementation method is: taking the first service as an example, the core network device can determine the maximum number of data packets that are allowed to be continuously unsuccessfully transmitted according to the lifetime of the first service. For example, the number of data packets that are continuously unsuccessfully transmitted defined by the lifetime of the first service is a, and the core network device can determine that the maximum number of data packets that are allowed to be continuously unsuccessfully transmitted is b; wherein a is greater than b, for example, a=2, b=1 or a=3, b=1 or 2. Further, the core network device can send the maximum number of data packets that are allowed to be continuously unsuccessfully transmitted (such as b) to the network device. Accordingly, taking the downlink transmission as an example, when the network device determines that the number of data packets that are continuously unsuccessfully transmitted is greater than or equal to b, the transmission reliability of the next data packet can be improved, so that the terminal device can successfully receive the next data packet, avoiding service interruption at the application layer.

[0114] In another example, the survival time can be defined as the number of consecutive transmission cycles with unsuccessful transmission (e.g., c), where the unsuccessful transmission cycle can refer to a transmission cycle in which there are unsuccessful transmission of data packets, or a transmission cycle in which the number of unsuccessful transmission of data packets is greater than or equal to a first threshold, or a transmission cycle in which the amount of unsuccessful transmission of data is greater than or equal to a second threshold. If the number of consecutive transmission cycles with unsuccessful transmission is greater than or equal to c, the service will be interrupted at the application layer. For example, see Figure 3b As shown, 2 data packets can be transmitted in one transmission cycle, the first threshold is 1, and c is 2. That is to say, when the number of data packets that are not successfully transmitted in each transmission cycle is greater than or equal to 1 in two consecutive transmission cycles, the service is interrupted at the application layer.

[0115] For this example, in order to avoid service interruption at the application layer, a possible implementation is that, taking the first service as an example, the core network device can determine the maximum number of transmission cycles that are allowed to be continuously unsuccessful according to the lifetime of the first service. For example, the number of transmission cycles that are continuously unsuccessful defined by the lifetime of the first service is c, and the core network device can determine the maximum number of data packets that are allowed to be continuously unsuccessful as d; wherein c is greater than d, for example, c=2, d=1 or c=3, d=1 or 2. Further, the core network device can send the maximum number of transmission cycles that are allowed to be continuously unsuccessful (for example, d) to the network device, and optionally, the core network device can also send the first threshold or the second threshold to the network device (in other possible examples, the first threshold and the second threshold can also be pre-defined by the protocol); accordingly, taking the downlink transmission as an example, when the network device determines that the number of transmission cycles that are continuously unsuccessful is greater than or equal to d, the transmission reliability of the data packets of the next transmission cycle can be improved, so that the terminal device can successfully receive the data packets of the next transmission cycle, avoiding service interruption at the application layer.

[0116] It should be noted that, taking the following transmission as an example, the data packets not successfully transmitted mentioned above may include:

[0117] (1) The PDCP layer of the network device determines that the data packet has failed to be transmitted (i.e., failed to be sent). There are multiple ways for the PDCP layer of the network device to determine that the data packet has failed to be transmitted: for example, the PDCP layer of the network device processes the data packet to obtain a PDCP PDU, and delivers it to the RLC layer, which delivers it to the MAC layer, which delivers it to the physical layer, and then the physical layer sends it to the terminal device; if the physical layer of the network device receives a NACK from the terminal device or does not receive an ACK within a set time, it can be determined that the data packet has failed to be transmitted, and then the physical layer notifies the MAC layer, which notifies the RLC layer, and then the RLC notifies the PDCP layer. For another example, when the network device includes separate CU and DU, the DU may periodically (such as in each transmission period) send a data packet sending status report to the CU, and then the PDCP layer in the CU may determine whether the data packet transmission fails based on the sending status report; or, the DU detects that there is a data packet transmission failure in consecutive transmission periods (such as triggering the lifetime timer of the downlink data packet), and sends a data packet transmission status report to the CU, and then the PDCP layer in the CU may determine whether the data packet transmission fails based on the sending status report; or, the CU requests the DU to report the data packet transmission status report, and accordingly, the DU sends the data packet transmission status report to the CU, and then the PDCP layer in the CU may determine whether the data packet transmission fails based on the data packet transmission status report.

[0118] The transmission status report may indicate the transmission status (i.e., transmission success or failure) of the PDCP PDUs corresponding to one or more PDCP sequence numbers (SN). For example, if multiple PDCP PDUs are cascaded at the RLC layer, there may be multiple PDCP PDUs in a transmission block of the MAC layer. In this case, if the MAC layer of the DU determines that a transmission block has not been successfully transmitted, it may indicate the transmission status of all PDCP PDUs in the transmission block to the CU.

[0119] (2) Data packets discarded due to the expiration of the PDCP layer discard timer. Specifically, after the PDCP layer of the network device receives a data packet (such as a PDCP SDU), it will start a discard timer. After the discard timer expires, the PDCP layer will discard the data packet, that is, even if the data packet has not been sent on the air interface, it will still be discarded. In an example, the discard timer can be 10ms or 20ms.

[0120] (3) Data packets that have not been successfully transmitted. Exemplarily, data packets that have not been successfully transmitted may include: data packets that the network device has sent to the terminal device through the air interface but has not yet received a confirmation response (such as ACK) from the terminal device. In the embodiment of the present application, the fact that the network device has sent a data packet to the terminal device through the air interface but has not yet received a confirmation response from the terminal device does not absolutely mean that the data packet has not been successfully received by the terminal device, or that the data packet will not be successfully received by the terminal device thereafter. It is possible that the data packet has been successfully received by the terminal device, but the terminal device has not yet sent a confirmation response to the network device; it is also possible that the data packet has been successfully received by the terminal device, and the terminal device has also sent a confirmation response to the network device, but the network device has not yet received the confirmation response; it is also possible that the data packet is not currently successfully received by the terminal device, but is later successfully received by the terminal device, and the terminal device sends a confirmation response corresponding to the data packet to the network device.

[0121] It should be noted that the difference between the “ACK has not been received from the terminal device” described in (3) above and the “ACK has not been received within the set time” in (1) above is that: “ACK has not been received from the terminal device” means that the set time has not yet been exceeded, so it is possible to receive an ACK from the terminal device within the set time; while “ACK has not been received within the set time” means that the set time has exceeded and it is determined that the ACK has not been received within the set time.

[0122] It is understandable that the above description is based on downlink transmission as an example, and the above transmission situation can refer to the description of downlink transmission, and the details are not repeated. In addition, the amount of data not successfully transmitted mentioned above can be the amount of data included in one or more data packets not successfully transmitted.

[0123] 3. Switching process of terminal equipment

[0124] As the terminal device moves, it may move from the coverage of the source network device to the coverage of the target network device. In this case, the terminal device can switch from the source network device to the target network device. Taking the 5G communication system as an example, Figure 4 A possible switching process diagram is shown in FIG. Figure 4 As shown, the process includes:

[0125] Step 401: The core network device sends a PDU session resource setup request message to the first network device, requesting the first network device to establish a PDU session, where the PDU session may include a first quality of service (QoS) flow.

[0126] Here, the PDU session resource establishment request message may include the QoS parameters of the first QoS flow. Taking the first QoS flow as a guaranteed bit rate (GBR) QoS flow as an example, the QoS parameters of the first QoS flow may include a 5G service quality identifier (5G QoS identifier, 5QI), etc. Exemplarily, the PDU session resource establishment request message may also include data information that is allowed to be unsuccessfully transmitted and feature information of the first service (for details, see the description in Embodiment 1).

[0127] Step 402: The first network device determines configuration information of one or more DRBs or LCHs according to the QoS parameters of the first QoS flow, and sends an RRC reconfiguration message 1 to the terminal device. The RRC reconfiguration message 1 may include configuration information of one or more DRBs or LCHs.

[0128] Exemplarily, considering that the lifetimes of different services may be different, in an embodiment of the present application, the first network device can map the QoS flows of services with different lifetimes to different wireless bearers, so that for services with different lifetimes, even if they have the same QoS level, they will not be multiplexed in a transmission block, which is convenient for the network side to detect the data packet transmission status of each service (such as the number of consecutive data packets that have not been successfully transmitted for each service). For example, QoS flow 1 is used to carry service 1, and QoS flow 2 is used to carry service 2. The lifetime of service 1 is different from the lifetime of service 2; in this case, the first network device can map QoS flow 1 and QoS flow 2 to different wireless bearers, which is convenient for subsequent detection of the data packet transmission status of service 1 and the data packet transmission status of service 2, avoiding interruption of service 1 and service 2 at the application layer.

[0129] Step 403: The terminal device performs corresponding configuration according to the RRC reconfiguration message 1, and sends an RRC reconfiguration completion message 1 to the first network device.

[0130] Step 404: The terminal device and the first network device perform uplink and / or downlink data transmission.

[0131] Step 405: The first network device sends a handover request message to the second network device. The handover request is used to notify the second network device that the terminal device is ready to be handed over to the second network device.

[0132] Here, before sending the switching request message, the first network device can send measurement configuration information to the terminal device. Accordingly, the terminal device can perform measurements according to the measurement configuration information sent by the first network device. When the triggering condition of the measurement report is met, the terminal device can send a measurement report to the first network device. Then the first network device makes a switching decision according to the measurement report sent by the terminal device, that is, the first network device can determine the target cell according to the measurement report sent by the terminal device, and decide to switch the terminal device to the second network device (that is, the network device to which the target cell belongs).

[0133] Step 406: The second network device sends a handover request confirmation message (handoverrequest ack) to the first network device.

[0134] Exemplarily, after receiving the handover request message sent by the first network device, the second network device can perform handover preparation according to the handover request message, and allocate the relevant configuration required for the terminal device to switch to the target cell, for example, the target cell allocates a cell radio network temporary identifier (C-RNTI) to the terminal device, and random access resources required for the terminal device to access the target cell, etc. Among them, the handover request confirmation message may include the C-RNTI and random access resources allocated by the target cell to the terminal device.

[0135] Step 407: The first network device sends an RRC reconfiguration message 2 including a switching command to the terminal device.

[0136] Here, the handover command may include the C-RNTI allocated by the target cell to the terminal device and the random access resource information required for the terminal device to access the target cell.

[0137] Step 408: The terminal device initiates random access to the second network device according to the switching command.

[0138] Here, the terminal device may disconnect the RRC connection with the first network device, or may maintain the RRC connection with the first network device, without specific limitation.

[0139] It should be noted that in some possible scenarios, the terminal device may send uplink data to the second network device during the random access process.

[0140] Step 409: The first network device sends an SN status transfer message to the second network device.

[0141] For downlink transmission, in one example, the SN status transmission message may include a DL PDCP SN, and the DL PDCP SN value is used to indicate the starting sequence number value when the second network device allocates a PDCP SN to a downlink data packet that has not been allocated a PDCP SN (i.e., the second network device allocates a PDCP SN to the downlink data packet starting from the DL PDCP SN value). In this case, the PDCP SN allocated by the second network device to the downlink data packet and the PDCP SN allocated by the first network device to the downlink data packet may be continuous, for example, if the last PDCP SN allocated by the first network device to the downlink data packet is 100, then the first PDCP SN allocated by the second network device to the downlink data packet is 101. Alternatively, the SN status transmission message may include the first sequence number (i.e., the second network device allocates a PDCP SN to the downlink data packet starting from the first sequence number), that is, the first network device may indicate a new sequence number (i.e., the first sequence number) to the second network device. Alternatively, the SN status transmission message may not include the above-mentioned DL PDCP SN value or the first sequence number. In this case, the second network device may allocate PDCP SNs for downlink data packets starting from the second sequence number. The second sequence number may be a default sequence number (such as 0) or a sequence number predefined by the protocol, and is not specifically limited. It can be understood that if the second network device allocates PDCP SNs for downlink data packets starting from the first sequence number or the second sequence number, the PDCP SNs allocated by the second network device for the downlink data packets and the PDCP SNs allocated by the first network device for the downlink data packets may be discontinuous.

[0142] For uplink transmission, in one example, the SN status transmission message may include a UL PDCP SN, where the UL PDCP SN is used to indicate the PDCP SN of the first uplink data packet that was not successfully transmitted.

[0143] It should be noted that the above-mentioned SN status transmission message may also be replaced by other message names, such as early forwarding transmission message, without specific limitation.

[0144] Step 410: The first network device forwards the cached data packet to the second network device.

[0145] For downlink transmission, in one example, the first network device can forward downlink data packets that have not yet been sent (including downlink data packets that have not yet been processed by PDCP and newly sent by the UPF network element to the first network device, and downlink data packets that have been processed by PDCP but not yet sent) to the second network device.

[0146] For uplink transmission, in one example, the first network device can forward the out-of-order uplink data packets received from the terminal device (starting from the first out-of-order uplink data packet, and all other data packets after the first out-of-order packet (if any)) to the second network device. Here, out-of-order means that the PDCP SN of the uplink data packets is discontinuous due to the failure of uplink data packet transmission. For example, the terminal device sends data packet 1, data packet 2, data packet 3 and data packet 4 to the first network device, but the first network device only receives data packet 1, data packet 3 and data packet 4, and data packet 2 fails to be transmitted. In this case, the first network device can forward data packet 3 (i.e., the first out-of-order uplink data packet) and data packet 4 to the second network device.

[0147] Step 411, the terminal device performs a random access process with the second network device, and after the random access process is successful, the terminal device sends an RRC reconfiguration completion message 2 to the second network device to indicate that the terminal device has successfully switched to the second network device.

[0148] Step 412: The terminal device transmits data with the second network device.

[0149] It should be noted that: in the above switching process, the first network device is the source network device, and the second network device is the target network device. The process described in the above steps 401 to 412 only illustrates some possible steps. In the specific implementation, other possible steps may also be included. For example, after the first network device receives the PDU session resource establishment request message, it may also return a PDU session resource establishment response message to the core network device.

[0150] Based on the above-mentioned related technical features, the embodiments of the present application will mainly study how to avoid service interruption at the application layer in the scenario where terminal equipment is switched.

[0151] Exemplarily, for downlink transmission, the communication method provided in the embodiment of the present application may include: the source network device of the terminal device sends N data packets of the first service and auxiliary information (for the convenience of distinction, referred to as the first auxiliary information in the embodiment of the present application) to the target network device, and accordingly, the target network device can improve the transmission reliability of one or more downlink data packets to be sent according to the first auxiliary information, thereby effectively avoiding the interruption of the service at the application layer due to the switching of the terminal device. For uplink transmission, the communication method provided in the embodiment of the present application may include: the source network device of the terminal device sends auxiliary information to the target network device (for the convenience of distinction, referred to as the second auxiliary information in the embodiment of the present application), and accordingly, the target network device can improve the transmission reliability of one or more uplink data packets to be scheduled according to the second auxiliary information, thereby effectively avoiding the interruption of the service at the application layer due to the switching of the terminal device.

[0152] It should be noted that, taking downlink transmission as an example, after the target network device receives the first auxiliary information from the source network device, the specific operation performed by the target network device based on the first auxiliary information may depend on the internal implementation of the target network device; for example, the target network device may improve the transmission reliability of one or more downlink data packets to be sent based on the first auxiliary information, or the target network device may also perform other possible operations based on the first auxiliary information to avoid interruption of the service at the application layer due to the switching of the terminal device. That is to say, in the embodiment of the present application, the first auxiliary information is sent from the source network device to the target network device, and then the target network device may perform related operations (the specific operations may not be limited) based on or with reference to the first auxiliary information, thereby providing a possible idea for solving the above technical problem (i.e., how to avoid interruption of the service at the application layer in the scenario where the terminal device switches).

[0153] The communication method provided in the embodiments of the present application is described in detail below in combination with Embodiments 1 to 4.

[0154] Embodiment 1

[0155] Figure 5 This is a flow chart corresponding to the communication method provided in Example 1 of the present application, such as Figure 5 As shown, the method includes:

[0156] Step 500: The source network device sends a first message to the target network device, the first message including data information that is not allowed to be transmitted successfully and / or feature information of the first service. Accordingly, the target network device may receive the first message and obtain the data information that is not allowed to be transmitted successfully and the feature information of the first service.

[0157] Exemplarily, the first message may be a switching request message sent by the source network device to the target network device, or other possible messages, which are not specifically limited.

[0158] (1) The data information that is allowed to be not successfully transmitted may be determined according to the lifetime of the first service, for example, the data information that is allowed to be not successfully transmitted may include a third threshold or a fourth threshold. The third threshold indicates the maximum number of data packets that are allowed to be not successfully transmitted continuously, and the fourth threshold indicates the maximum number of transmission cycles that are allowed to be not successfully transmitted continuously.

[0159] It should be noted that the above-described data information that is allowed to be not successfully transmitted can be applicable to both uplink transmission and downlink transmission unless otherwise specified. However, in specific implementations, it can be applicable only to uplink transmission, or only to downlink transmission, or to both uplink transmission and downlink transmission.

[0160] In addition, in the embodiment of the present application, the data information that is allowed to fail to be transmitted may include the third threshold or the fourth threshold is used as an example for description. In other possible embodiments, the data information that is allowed to fail to be transmitted may include other possible information, such as the fifth threshold. The fifth threshold represents the maximum amount of data that is allowed to fail to be transmitted continuously.

[0161] (2) For downlink transmission, the characteristic information of the first service may include at least one of the following: the duration of the transmission cycle of the downlink data packet, the number of downlink data packets arriving at the source network device within a transmission cycle (i.e., the number of downlink data packets included in a transmission cycle, or the number of downlink data packets transmitted in a transmission cycle), the amount of data arriving at the source network device within a transmission cycle, the end time information of the downlink data packet arriving at the source network device within at least one transmission cycle, and the start time information of the downlink data packet arriving at the source network device within at least one transmission cycle. Among them, the end time information of the downlink data packet arriving at the source network device within a transmission cycle may be: the time information of the last downlink data packet arriving at the source network device within a transmission cycle; the start time information of the downlink data packet arriving at the source network device within a transmission cycle may be: the time information of the first downlink data packet arriving at the source network device within a transmission cycle. It can be understood that the start time information of the downlink data packet arriving at the source network device within the first transmission cycle of the first service is: the start time information of the downlink data packet arriving at the source network device.

[0162] For uplink transmission, the characteristic information of the first service may include at least one of the following: the duration of the transmission period of the uplink data packet, the number of uplink data packets that arrive at the terminal device within one transmission period (the number of uplink data packets included in one transmission period, or the number of uplink data packets transmitted in one transmission period), the amount of uplink data that arrives at the terminal device within one transmission period, the end time information of the uplink data packets within at least one transmission period arriving at the terminal device, and the start time information of the uplink data packets within at least one transmission period arriving at the terminal device.

[0163] (3) In the embodiment of the present application, there may be multiple ways for the source network device to obtain the data information that is allowed to be not successfully transmitted and the characteristic information of the first service. For example, the source network device receives a PDU session resource establishment request message from the core network device, and the PDU session resource establishment request message includes the data information that is allowed to be not successfully transmitted and the characteristic information of the first service.

[0164] It should be noted that the above step 500 is an optional step.

[0165] Step 5011: The source network device sends N downlink data packets of a first service and first auxiliary information to the target network device. The first auxiliary information can be used to indicate the transmission status of at least one downlink data packet before the N downlink data packets.

[0166] Optionally, the first auxiliary information may also be used to indicate a correspondence between a downlink data packet and a transmission cycle, and / or the number of downlink data packets arriving at the source network device within a transmission cycle.

[0167] It can be understood that if in the above step 500, the characteristic information of the first service sent by the source network device to the target network device includes the number of downlink data packets arriving at the source network device within a transmission cycle (or other information that can determine the number of downlink data packets arriving at the source network device within a transmission cycle), then the first auxiliary information may no longer indicate the number of downlink data packets arriving at the source network device within a transmission cycle. Alternatively, if the first auxiliary information indicates the number of downlink data packets arriving at the source network device within a transmission cycle, the characteristic information of the first service may no longer include the number of downlink data packets arriving at the source network device within a transmission cycle (or other information that can determine the number of downlink data packets arriving at the source network device within a transmission cycle), or the source network device may no longer send the characteristic information of the first service to the target network device.

[0168] Step 5012: The target network device receives N downlink data packets and first auxiliary information, and determines the transmission status of at least one downlink data packet before the N downlink data packets based on the first auxiliary information.

[0169] The relevant technical features involved in the first auxiliary information are explained below.

[0170] 1. Explain N downlink data packets.

[0171] The N downstream data packets may include the downstream data packets that have not been sent by the source network device. The source network device may send the N downstream data packets to the target network device (see Figure 4 For example, see step 410. Figure 6 As shown, data packets 1 to 6 are downlink data packets that have been sent by the source network device, data packets 2 to 5 are all successfully transmitted, and data packets 1 and 6 are not successfully transmitted; data packets 7 to 10 are downlink data packets that have not yet been sent. In this case, the N downlink data packets may include data packets 7 to 10.

[0172] 2. Explain at least one data packet before N downlink data packets.

[0173] At least one data packet before the N downlink data packets may include a data packet that is successfully transmitted and / or a data packet that is not successfully transmitted. Exemplarily, the at least one data packet before the N downlink data packets may be at least one downlink data packet among the W downlink data packets before the N downlink data packets. The last downlink data packet among the W downlink data packets is adjacent to the first downlink data packet among the N downlink data packets; see Figure 6 , the first downlink data packet among the N downlink data packets is data packet 7, and the adjacent data packet before data packet 7 is data packet 6. Therefore, the last downlink data packet among the W downlink data packets may be data packet 6.

[0174] The value of W can be pre-defined by the protocol, or can be flexibly set by the source network device. For example, W can be equal to the size of the PDCP window, and the size of the PDCP window can be equal to half of the maximum value of the PDCP SN. For another example, the source network device can set the value of W based on the data information that is allowed to be unsuccessfully transmitted. For example, the data information that is allowed to be unsuccessfully transmitted includes a third threshold, then W can be an integer greater than or equal to the third threshold; further, in order to save transmission resources, W can be equal to the first threshold, for example, if the third threshold is 2, then W can be equal to 2. For another example, the data information that is allowed to be unsuccessfully transmitted includes a fourth threshold, assuming that two data packets are transmitted in one transmission cycle, then W can be an integer greater than or equal to twice the fourth threshold, for example, if the fourth threshold is 2, then W can be equal to 4.

[0175] It should be noted that in other possible examples, it can also be described as: at least one data packet before N downlink data packets can be at least one downlink data packet within a preset time period before the N downlink data packets; the last data packet within the preset time period is adjacent to the first data packet among the N data packets. Here, the duration of the preset time period can be pre-defined by the protocol, or can be flexibly set by the source network device. For example, the duration of the preset time period can be determined according to the size of the PDCP window. For example, if one transmission cycle includes one data packet, and the size of the PDCP window is 1024, the duration of the preset time period can be equal to the length of 1024 transmission cycles. In the following, the description will be taken as an example that at least one data packet before N downlink data packets is at least one downlink data packet among the W downlink data packets before the N downlink data packets.

[0176] 3. A possible implementation of the first auxiliary information indicating the transmission status of at least one data packet before N downlink data packets is described.

[0177] There are many ways to implement the first auxiliary information indicating the transmission status of at least one data packet before N downlink data packets. Two possible examples are described below.

[0178] In one example, the first auxiliary information may include an identifier of a data packet that was not successfully transmitted before N data packets. For example, the first auxiliary information may include an identifier of a downlink data packet that was not successfully transmitted among the W downlink data packets before the N data packets. Here, the identifier of the downlink data packet may be the PDCP SN of the downlink data packet, or may be the Count value of the downlink data packet, or may be other information used to identify the downlink data packet. The Count value of the downlink data packet may be obtained based on the PDCP SN and the hyper frame number (HFN) of the downlink data packet. For example, see Figure 6 , assuming W=6, the first auxiliary information may include the PDCP SN of data packet 1 and data packet 6; accordingly, the target network device may determine, based on the first auxiliary information, that the transmission status of data packet 1 and data packet 6 is unsuccessful transmission, and the transmission status of data packet 2 to data packet 5 is successful transmission.

[0179] In another example, the first auxiliary information may include an identifier of the first downlink data packet that was not successfully transmitted before N downlink data packets, and transmission status information of M downlink data packets after the first downlink data packet that was not successfully transmitted, and the last downlink data packet among the M downlink data packets is adjacent to the first downlink data packet among the N downlink data packets. Among them, the first downlink data packet that was not successfully transmitted before the N downlink data packets may be an identifier of the first downlink data packet that was not successfully transmitted among the W downlink data packets before the N downlink data packets, and the last downlink data packet among the M downlink data packets is the last downlink data packet among the W downlink data packets. Exemplarily, the transmission status information of the M downlink data packets may include a bitmap, and the bitmap includes M bits, and the M bits correspond to the M downlink data packets respectively, and the value of each bit is used to indicate the transmission status of the downlink data packet corresponding to the bit, for example, if the value of a certain bit is 1, it means that the transmission status of the downlink data packet corresponding to the bit is successfully transmitted, and if the value is 0, it means that the transmission status of the downlink data packet corresponding to the bit is not successfully transmitted. For example, if the PDCP SN of the first unsuccessful data packet among W downlink data packets is n, the value of the mth bit (from right to left) in the bitmap is used to indicate the transmission status of the downlink data packet whose PDCP SN is (m+n) mod(1+maximum value of PDCP SN). Figure 6 Assuming that the first downlink data packet that is not successfully transmitted among the W downlink data packets is data packet 1 (eg, the PDCP SN of data packet 1 is 1), the first auxiliary information may include the PDCP SN of data packet 1 and a bit map (01111).

[0180] 4. A possible implementation of the first auxiliary information indicating the number of downlink data packets arriving at the source network device within a transmission cycle is described.

[0181] There may be many ways to implement the first auxiliary information indicating the number of downlink data packets arriving at the source network device within a transmission cycle. Two possible examples are described below.

[0182] In an example, the first auxiliary information may include the number of downlink data packets arriving at the source network device within a transmission cycle.

[0183] In another example, the first auxiliary information may include the time information when some or all of the N downstream data packets arrive at the source network device. In this way, the target network device can determine that one or more data packets with relatively close time information arriving at the source network device belong to the same transmission cycle based on the time information when some or all of the N downstream data packets arrive at the source network device, and then the number of downstream data packets arriving at the source network device within a transmission cycle (or the amount of downstream data arriving at the source network device within a transmission cycle) can be obtained. Among them, the judgment criteria for relatively close time information are not limited in the embodiments of the present application.

[0184] Taking the example that the first auxiliary information includes the time information when N downlink data packets arrive at the source network device, the time information when the N downlink data packets arrive at the source network device may be as shown in Table 1, or may also be as shown in Table 2.

[0185] Table 1: Example 1 of the time information of N downstream data packets arriving at the source network device

[0186] Time information 1 Time information 2 …… Time information N

[0187] Among them, time information 1 in Table 1 indicates the time information when the first data packet among N downstream data packets arrives at the source network device, time information 2 indicates the time information when the second data packet among N downstream data packets arrives at the source network device, and time information N indicates the time information when the Nth downstream data packet among N downstream data packets arrives at the source network device. After the target network device receives the information shown in Table 3, if it is determined that time information 1 and time information 2 are close, but time information 2 and time information 3 are not close, it can be determined that the first data packet and the second data packet belong to the same transmission cycle.

[0188] Table 2: Example 2 of the time information of N downstream data packets arriving at the source network device

[0189]

[0190]

[0191] Among them, the first row in Table 2 indicates that the time information when the downlink data packet with PDCP SN as PDCP SN-1 arrives at the source network device is time information 1, and the second row indicates that the time information when the downlink data packet with PDCP SN as PDCP SN-2 arrives at the source network device is time information 2, and so on. The time information when the downlink data packet with PDCP SN as PDCP SN-N arrives at the source network device is time information N.

[0192] In another example, the first auxiliary information may include the time information of the last data packet in at least one transmission cycle arriving at the source network device (i.e., the end time information of the downlink data packet in at least one transmission cycle arriving at the source network device), while the time information of other data packets in the transmission cycle arriving at the source network device may no longer be indicated. In this case, the target network device can distinguish the end of the current transmission cycle and the beginning of the next transmission cycle based on the end time information.

[0193] In another example, the first auxiliary information may include the time information of the first data packet arriving at the source network device within at least one transmission cycle (i.e., the start time information of the downlink data packet arriving at the source network device within at least one transmission cycle), while the time information of other data packets arriving at the source network device within the transmission cycle may no longer be indicated. In this case, the target network device can distinguish the end of the previous transmission cycle and the beginning of the current transmission cycle based on the start time information.

[0194] 5. A possible implementation of the correspondence between the first auxiliary information indicating the downlink data packet and the transmission period is described.

[0195] There may be many ways to implement the correspondence between the first auxiliary information indicating the downlink data packet and the transmission period. Two possible examples are described below.

[0196] In one example, the first auxiliary information may include an identifier of a downlink data packet included in at least one transmission period. Taking the first auxiliary information including identifiers of downlink data packets included in two transmission periods as an example, as shown in Table 3, it is an example of identifiers of downlink data packets included in two transmission periods.

[0197] Table 3: Example of identification of downlink data packets included in two transmission cycles

[0198] Packet 1 ID, Packet 2 ID Packet 3 ID, Packet 4 ID

[0199] The first row in Table 3 indicates that data packet 1 and data packet 2 belong to one transmission cycle, and the second row indicates that data packet 3 and data packet 4 belong to one transmission cycle. In this way, after receiving the information shown in Table 3, the target network device can determine that data packet 1 and data packet 2 belong to one transmission cycle, data packet 3 and data packet 4 belong to one transmission cycle, and so on. It can also be determined that data packet 5 and data packet 6 belong to one transmission cycle, data packet 7 and data packet 8 belong to one transmission cycle, and so on.

[0200] In another example, the first auxiliary information may include an identifier of the first downlink data packet or the last downlink data packet included in each transmission cycle in at least one transmission cycle, and the number of downlink data packets included in each transmission cycle. For example, the number of downlink data packets included in each transmission cycle is 2, and the PDCP SN of the first data packet in a transmission cycle is 1; in this way, after receiving the first auxiliary information, the target network device can determine that data packet 1 (PDCP SN is 1) and data packet 2 belong to a transmission cycle, data packet 3 and data packet 4 belong to a transmission cycle, and so on.

[0201] Optionally, the above may also include: Step 5013, the target network device determines whether to improve or not improve the transmission reliability of P downlink data packets, and sends P downlink data packets. The P downlink data packets may be the first P downlink data packets among the N downlink data packets.

[0202] For example, if the target network device determines that the preset conditions are met, the transmission mode of the P downlink data packets is determined to be the second transmission mode, and the P downlink data packets are sent using the second transmission mode; if it is determined that the preset conditions are not met, the transmission mode of the P downlink data packets is determined to be the first transmission mode, and the P downlink data packets are sent using the first transmission mode. Here, the transmission reliability of the first transmission mode and the second transmission mode are different, for example, the transmission reliability of the second transmission mode is greater than the transmission reliability of the first transmission mode. Therefore, determining that the transmission mode of the P downlink data packets is the second transmission mode can also be understood as: improving the transmission reliability of the P downlink data packets; determining that the transmission mode of the P downlink data packets is the first transmission mode can also be understood as: not improving the transmission reliability of the P downlink data packets. Among them, there can be many ways to improve the transmission reliability of the P downlink data packets, such as reducing the MCS of the downlink scheduling resources, increasing the sending priority of the P downlink data packets, etc.

[0203] Exemplarily, if the data information that is allowed to be unsuccessfully transmitted includes a third threshold, determining the preset condition may include determining that there are K1 (K1 is greater than or equal to the third threshold) consecutive downlink data packets that are not successfully transmitted, and the last downlink data packet among the K1 downlink data packets is adjacent to the first downlink data packet among the N downlink data packets. In this case, the P data packets may refer to the first downlink data packet among the N downlink data packets, such as Figure 6 Packet 7 in .

[0204] If the data information that is not successfully transmitted is allowed to include the fourth threshold, determining that the preset condition is met includes determining that there are K2 (K2 is greater than or equal to the fourth threshold) consecutive transmission cycles that are not successfully transmitted, and the downlink data packets included in the next adjacent transmission cycle of the K2 transmission cycles belong to the N downlink data packets. In this case, the P data packets may refer to the downlink data packets included in the next adjacent transmission cycle packets of the K2 transmission cycles. For example Figure 6 In the figure, a transmission cycle includes two data packets, data packet 1 and data packet 2 belong to one transmission cycle (called transmission cycle 1), and so on, data packet 7 and data packet 8 belong to one transmission cycle (called transmission cycle 4). Assume that K2 transmission cycles include transmission cycle 3 (that is, the transmission cycle to which data packet 5 and data packet 6 belong), and then P data packets can refer to data packet 7 and data packet 8.

[0205] Step 5021: The source network device sends second auxiliary information to the target network device. The second auxiliary information can be used to indicate the corresponding relationship between the uplink data packet and the transmission period.

[0206] Here, the manner in which the second auxiliary information indicates the correspondence between the uplink data packet and the transmission period may adopt the above-mentioned description of the first auxiliary information. For example, the second auxiliary information may include the identifier of the uplink data packet included in each transmission period in at least one transmission period; for another example, the second auxiliary information may include the number of uplink data packets arriving at the terminal device within a transmission period and the identifier of the first uplink data packet or the last uplink data packet within a transmission period.

[0207] Optionally, the second auxiliary information can also be used to indicate the transmission status of at least one uplink data packet. The at least one uplink data packet can refer to at least one uplink data packet among Y uplink data packets, and the last uplink data packet among the Y uplink data packets can be the last uplink data packet received by the source network device; wherein, the value of Y can refer to the above description about W, and it should be noted that when the maximum value of DL PDCP SN and the maximum value of UL PDCP SN are the same, Y can be equal to W. wherein, the manner in which the second auxiliary information indicates the transmission status of at least one uplink data packet can adopt the above description about the first auxiliary information, for example, the second auxiliary information can include the identifier of the first uplink data packet that was not successfully transmitted among the Y uplink data packets and the transmission status information of other uplink data packets after the first uplink data packet that was not successfully transmitted.

[0208] In other possible embodiments, the source network device may also send a reception status report of at least one uplink data packet to the target network device. In this case, the second auxiliary information is used to no longer indicate the transmission status of at least one uplink data packet.

[0209] Optionally, the second auxiliary information may also be used to indicate the number of uplink data packets arriving at the source network device within a transmission cycle.

[0210] Step 5022: The target network device receives the second auxiliary information, and determines the correspondence between the uplink data packet and the transmission period according to the second auxiliary information.

[0211] Optionally, the method may further include: step 5023, the target network device determines whether to increase or not increase the transmission reliability of Q uplink data packets, and schedules Q uplink data packets, wherein the Q uplink data packets are uplink data packets to be sent by the terminal device to the target network device.

[0212] Here, there are many ways to improve the transmission reliability of the Q uplink data packets, such as reducing the MCS of the uplink scheduling resources, increasing the transmission priority of the Q uplink data packets, etc.

[0213] It should be noted that the downlink transmission process (such as step 5011 to step 5013) and the uplink transmission process (such as step 5011 to step 5023) described above can be implemented separately or in combination. When implemented in combination, the source network device can send the first auxiliary information and the second auxiliary information to the target network device through the same message, such as the source network device sends the first auxiliary information and the second auxiliary information to the target network device through the SN state transmission message (or other possible messages in the switching process such as early forwarding transmission messages); or, the source network device can also send the first auxiliary information and the second auxiliary information to the target network device through different messages, respectively, without specific limitation.

[0214] Using the above scheme, taking downlink transmission as an example, the source network device sends first auxiliary information to the target network device. The first auxiliary information can be used to indicate the transmission status of at least one downlink data packet before N downlink data packets, so that the target network device can promptly obtain the transmission status of at least one downlink data packet before N downlink data packets, and can determine whether to improve the transmission reliability of P data packets based on the transmission status of at least one downlink data packet before N downlink data packets, thereby effectively avoiding the problem of service interruption at the application layer due to the target network device being unable to promptly obtain the transmission status of at least one downlink data packet due to the switching of the terminal device.

[0215] Embodiment 2

[0216] Figure 7 This is a flow chart corresponding to the communication method provided in Example 2 of the present application, such as Figure 7 As shown, the method includes:

[0217] Step 700: The source network device sends a first message to the target network device, the first message including data information that is not allowed to be transmitted successfully and feature information of the first service. Accordingly, the target network device can receive the first message and obtain the data information that is not allowed to be transmitted successfully and feature information of the first service.

[0218] Step 7011: The source network device sends N downlink data packets of a first service and first auxiliary information to the target network device, wherein the first auxiliary information is used to indicate that transmission failure of the P downlink data packets is not allowed.

[0219] Here, the P downlink data packets may be the first P downlink data packets among the N downlink data packets. In one example, the first auxiliary information may include identifiers of the P downlink data packets. The identifiers of the P downlink data packets may be the PDCP SNs of the P downlink data packets, or may be the Count values ​​of the P downlink data packets, or may be other information for identifying the P downlink data packets.

[0220] For the PDCP SN of P downlink data packets, it should be noted that: Figure 4 In step 409, if the SN status transmission message includes a DL PDCP SN, the identifiers of the P downlink data packets may be the PDCP SNs of the P downlink data packets; if the SN status transmission message includes a first sequence number, that is, the second network device allocates PDCPSNs to the downlink data packets starting from the first sequence number, the identifiers of the P downlink data packets may be the PDCPSNs allocated to the P downlink data packets starting from the first sequence number; if the second network device allocates PDCP SNs to the downlink data packets starting from the second sequence number, the identifiers of the P downlink data packets may be the PDCP SNs allocated to the P downlink data packets starting from the second sequence number.

[0221] Step 7012: The target network device receives N downlink data packets and the first auxiliary information, and determines, based on the first auxiliary information, that transmission failure of the P downlink data packets is not allowed.

[0222] Optionally, the above may also include: Step 7013, the target network device determines to improve the transmission reliability of P downlink data packets, and sends P downlink data packets.

[0223] Step 7021: The source network device sends second auxiliary information to the target network device, wherein the second auxiliary information is used to indicate that transmission failure of the Q uplink data packets is not allowed.

[0224] Step 7022: The target network device receives the second auxiliary information, and determines, based on the second auxiliary information, that transmission failure of the Q downlink data packets is not allowed.

[0225] Here, the Q uplink data packets may be uplink data packets to be sent by the terminal device to the target network device. In one example, the second auxiliary information may include identifiers of the Q uplink data packets.

[0226] Optionally, the above may also include: Step 7023, the target network device determines to improve the transmission reliability of Q uplink data packets, and schedules the Q uplink data packets.

[0227] Using the above scheme, taking downlink transmission as an example, the source network device sends the first auxiliary information to the target network device, and the first auxiliary information is used to indicate that P downlink data packets are not allowed to fail in transmission, and then the target network device can improve the transmission reliability of the P downlink data packets according to the first auxiliary information, avoid the transmission failure of the P downlink data packets, and then avoid the interruption of the service at the application layer. In other words, the source network device can determine the downlink data packets that are not allowed to fail in transmission, and then indicate it to the target network device, so that the target network device can directly learn the downlink data packets that are not allowed to fail in transmission in a timely manner according to the first auxiliary information, thereby effectively saving the processing burden of the target network device.

[0228] Embodiment 3

[0229] Figure 8 This is a flow chart corresponding to the communication method provided in Example 3 of the present application, such as Figure 8 As shown, the method includes:

[0230] Step 800: The source network device sends a first message to the target network device, the first message including data information that is not allowed to be transmitted successfully and feature information of the first service. Accordingly, the target network device can receive the first message and obtain the data information that is not allowed to be transmitted successfully and feature information of the first service.

[0231] Step 8011: The source network device sends N downlink data packets of a first service and first auxiliary information to the target network device, wherein the first auxiliary information is used to indicate the state of the lifetime timer (downlink) of the first service.

[0232] In one example, the first auxiliary information may include at least one of the following: (1) status information of the lifetime timer, for example, the status information includes 1 bit, if the value of the bit is 1, it indicates that the lifetime timer is in a running state; if the value of the bit is 0, it indicates that the lifetime timer is in a stopped state. (2) time information when the downlink data packet that triggers the lifetime timer arrives at the source network device. (3) an identifier of the downlink data packet that triggers the lifetime timer. When the first auxiliary information includes (2) and / or (3), it can be understood that the first auxiliary information implicitly indicates that the lifetime timer is in a running state.

[0233] Step 8012: The target network device receives N downlink data packets and the first auxiliary information, and determines the state of the lifetime timer (downlink) according to the first auxiliary information.

[0234] Optionally, the above may also include: Step 8013, the target network device determines whether to improve or not to improve the transmission reliability of the P uplink data packets, and sends the P uplink data packets.

[0235] Here, if the first auxiliary information includes status information of the lifetime timer, the target network device may improve the transmission reliability of P downlink data packets based on the status information if it is determined that the lifetime timer is in a running state, in order to avoid interruption caused by the lifetime timer timing out; if it is determined that the lifetime timer is in a stopped state, the transmission reliability of the P downlink data packets may not be improved.

[0236] If the first auxiliary information includes the time information of the downlink data packet that triggers the survival time timer arriving at the source network device, for example, the downlink data packet that triggers the survival time timer is Figure 6 For the data packet 6 shown in the figure, the first auxiliary information may include the time information when the data packet 6 arrives at the source network device. In this case, the target network device can determine that the survival timer is in operation according to the first auxiliary information. In one example, the target network device can directly improve the transmission reliability of P downlink data packets; in another example, the target network device can determine whether it is necessary to improve the transmission reliability of P downlink data packets according to the time information when the data packet 6 arrives at the source network device and the data information that is allowed to be not successfully transmitted. For example, the data information that is allowed to be not successfully transmitted includes the third threshold, and the P data packets include data packet 7. For example, the third threshold is 4. In this case, even if the transmission of data packet 7 fails, it will not cause an interruption in the application layer, so the target network device may not improve the transmission reliability of data packet 7; for another example, the third threshold is 2. In this case, if the transmission of data packet 7 fails, it will cause an interruption in the application layer, so the target network device can improve the transmission reliability of data packet 7.

[0237] If the first auxiliary information includes the identifier of the downlink data packet that triggers the lifetime timer, the description that the first auxiliary information includes the time information of the downlink data packet that triggers the lifetime timer arriving at the source network device can be referred to and will not be repeated.

[0238] It can be seen from the above content that when the first auxiliary information includes (2) and / or (3), the target network device can more accurately determine whether it is necessary to improve the transmission reliability of P data packets.

[0239] Step 8021: The source network device sends second auxiliary information to the target network device, wherein the second auxiliary information is used to indicate the state of the lifetime timer (uplink) of the first service.

[0240] Step 8022: The target network device receives the second auxiliary information and determines the state of the lifetime timer (uplink) according to the second auxiliary information.

[0241] Optionally, the above may also include: Step 8023, the target network device determines whether to improve or not to improve the transmission reliability of the Q uplink data packets, and schedules the Q uplink data packets.

[0242] Using the above scheme, taking downlink transmission as an example, the source network device sends first auxiliary information to the target network device, and the first auxiliary information is used to indicate the status of the lifetime timer (downlink) of the first service, so that the target network device can determine whether to improve the transmission reliability of P data packets based on the status of the lifetime timer, thereby effectively avoiding the problem of service interruption at the application layer due to switching of terminal devices.

[0243] Embodiment 4

[0244] Fig. 9 This is a flow chart corresponding to the communication method provided in Example 4 of the present application, such as Fig. 9 As shown, the method includes:

[0245] Step 900: The source network device sends a first message to the target network device, the first message including data information that is not allowed to be successfully transmitted and feature information of the first service. Accordingly, the target network device can receive the first message and obtain the data information that is not allowed to be successfully transmitted and feature information of the first service.

[0246] Step 9011: The source network device sends N downlink data packets of the first service and first auxiliary information to the target network device. The first auxiliary information is used to indicate the number of downlink data packets that have not been successfully transmitted or the number of transmission cycles that have not been successfully transmitted; the last downlink data packet among the downlink data packets that have not been successfully transmitted is adjacent to the first downlink data packet among the N downlink data packets, and the downlink data packets included in the next adjacent transmission cycle of the transmission cycle that has not been successfully transmitted belong to the N downlink data packets.

[0247] Step 9012: The target network device receives the first auxiliary information and determines the number of consecutive unsuccessful transmission of data packets or the number of consecutive unsuccessful transmission cycles.

[0248] Optionally, the above may also include: Step 9013, the target network device determines whether to improve or not to improve the transmission reliability of the P uplink data packets, and sends the P uplink data packets.

[0249] Here, if the first auxiliary information is used to indicate the number of data packets that have not been successfully transmitted in succession, the target network device can determine whether the number of downlink data packets that have not been successfully transmitted in succession is greater than or equal to a third threshold. If so, the transmission reliability of P downlink data packets can be improved; if not, the transmission reliability of P downlink data packets may not be improved.

[0250] If the first auxiliary information is used to indicate the number of consecutive unsuccessful transmission cycles, the target network device can determine whether the number of consecutive unsuccessful transmission cycles is greater than or equal to a fourth threshold value. If so, the transmission reliability of the P downlink data packets can be improved; if not, the transmission reliability of the P downlink data packets may not be improved.

[0251] Step 9021: The source network device sends second auxiliary information to the target network device, wherein the second auxiliary information is used to indicate the number of uplink data packets that have not been successfully transmitted continuously or the number of transmission cycles that have not been successfully transmitted continuously.

[0252] Step 9022: The target network device determines the number of uplink data packets that have not been successfully transmitted consecutively or the number of transmission cycles that have not been successfully transmitted consecutively according to the second auxiliary information.

[0253] Optionally, the above may also include: Step 9023, the target network device determines whether to improve or not to improve the transmission reliability of the Q uplink data packets, and schedules the Q uplink data packets.

[0254] Using the above scheme, taking downlink transmission as an example, the source network device sends first auxiliary information to the target network device, and the first auxiliary information is used to indicate the number of downlink data packets that have not been successfully transmitted or the number of transmission cycles that have not been successfully transmitted. That is, the source network device can determine the number of downlink data packets that have not been successfully transmitted or the number of transmission cycles that have not been successfully transmitted, and indicate it to the target network device, so that the target network device can determine whether to improve the transmission reliability of P data packets, thereby effectively avoiding the problem of service interruption at the application layer due to switching of terminal devices.

[0255] Regarding the above-mentioned embodiments 1 to 4, it should be noted that:

[0256] (1) The step numbers of the flowcharts described in Examples 1 to 4 are only examples of the execution process and do not constitute a limitation on the order of execution of the steps. There is no strict execution order between the steps that have no temporal dependency relationship with each other in the embodiments of the present application. In addition, not all the steps shown in the flowcharts are steps that must be executed, and some steps can be added or deleted based on the actual needs of each flowchart.

[0257] (2) The above description focuses on the differences between different embodiments in Embodiment 1 to Embodiment 4. Except for the other contents of the differences, Embodiment 1 to Embodiment 4 can refer to each other. For example, the first message in Embodiment 2 to Embodiment 4 can refer to the description in Embodiment 1. In addition, each embodiment in Embodiment 1 to Embodiment 4 is described in detail for downlink transmission, and the implementation of uplink transmission can be adaptively referred to downlink transmission. In addition, N, M, W, Y, P, Q, K1, K2, etc. involved in the embodiments of the present application can all be positive integers.

[0258] (3) Some messages in the 5G communication system are used in the above-mentioned embodiments 1 to 4. However, in the specific implementation, different messages or message names may be used, and the embodiments of the present application are not limited to this.

[0259] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of device interaction. It is understandable that in order to achieve the above functions, the source network device and the target network device of the terminal device may include hardware structures and / or software modules corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the embodiments of the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0260] The embodiment of the present application can divide the source network device and the target network device into functional units according to the above method example. For example, each functional unit can be divided according to each function, or two or more functions can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of software functional units.

[0261] In the case of an integrated unit, Fig.10 A possible exemplary block diagram of the device involved in the embodiments of the present application is shown. Fig.10 As shown, the device 1000 may include: a processing unit 1002 and a communication unit 1003. The processing unit 1002 is used to control and manage the actions of the device 1000. The communication unit 1003 is used to support the communication between the device 1000 and other devices. Optionally, the communication unit 1003 is also called a transceiver unit, and may include a receiving unit and / or a sending unit, which are respectively used to perform receiving and sending operations. The device 1000 may also include a storage unit 1001 for storing program code and / or data of the device 1000.

[0262] The device 1000 may be the target network device in the above embodiment, or may be a chip set in the target network device. The processing unit 1002 may support the device 1000 to execute the actions of the target network device in each method example above. Alternatively, the processing unit 1002 mainly executes the internal actions of the target network device in the method example, and the communication unit 1003 may support the communication between the device 1000 and other devices.

[0263] Specifically, in one embodiment, the communication unit 1003 is used to: receive N data packets and auxiliary information of a first service from a source network device of a terminal device, the auxiliary information being used to indicate a transmission status of at least one data packet before the N data packets; and the processing unit 1002 is used to: determine the transmission status of the at least one data packet based on the auxiliary information; N is a positive integer.

[0264] In one possible design, the auxiliary information includes an identifier of a data packet that was not successfully transmitted before N data packets; or, the auxiliary information includes an identifier of a first data packet that was not successfully transmitted before N data packets, and transmission status information of M data packets after the first data packet that was not successfully transmitted, and the last data packet of the M data packets is adjacent to the first data packet of the N data packets; M is a positive integer.

[0265] In a possible design, the auxiliary information is also used to indicate the correspondence between the data packet and the transmission cycle.

[0266] In one possible design, the auxiliary information includes an identifier of a data packet included in at least one transmission cycle; or, the auxiliary information includes an identifier of the first data packet or the last data packet included in each transmission cycle in at least one transmission cycle, and the number of data packets or the amount of data included in each transmission cycle.

[0267] In a possible design, the communication unit 1003 is further used to: receive data information that is allowed to be unsuccessfully transmitted from the source network device, where the data information that is allowed to be unsuccessfully transmitted is determined according to the lifetime of the first service.

[0268] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0269] The apparatus 1000 may be the source network device in the above embodiment, or may be a chip disposed in the source network device. The processing unit 1002 may support the apparatus 1000 in executing the actions of the source network device in each method example above. Alternatively, the processing unit 1002 mainly executes the internal actions of the source network device in the method example, and the communication unit 1003 may support the communication between the apparatus 1000 and other devices.

[0270] Specifically, in one embodiment, the processing unit 1002 is used to: determine auxiliary information; the communication unit 1003 is used to: send N data packets and auxiliary information of the first service to the target network device of the terminal device; wherein the auxiliary information is used to indicate the transmission status of at least one data packet before the N data packets; N is a positive integer.

[0271] In one possible design, the auxiliary information includes an identifier of a data packet that was not successfully transmitted before N data packets; or, the auxiliary information includes an identifier of a first data packet that was not successfully transmitted before N data packets, and transmission status information of M data packets after the first data packet that was not successfully transmitted, and the last data packet of the M data packets is adjacent to the first data packet of the N data packets; M is a positive integer.

[0272] In a possible design, the auxiliary information is also used to indicate the correspondence between the data packet and the transmission cycle.

[0273] In one possible design, the auxiliary information includes an identifier of a data packet included in at least one transmission cycle; or, the auxiliary information includes an identifier of the first data packet or the last data packet included in each transmission cycle in at least one transmission cycle, and the number of data packets or the amount of data included in each transmission cycle.

[0274] In a possible design, the communication unit 1003 is further used to: send data information that is allowed to be unsuccessfully transmitted to the target network device, where the data information that is allowed to be unsuccessfully transmitted is determined based on the lifetime of the first service.

[0275] In one possible design, the data information that is allowed to fail to be transmitted successfully includes at least one of the maximum number of data packets that are allowed to fail to be transmitted successfully in a row and the maximum number of transmission cycles that are allowed to fail to be transmitted successfully in a row; wherein, the transmission cycle that is not successfully transmitted is a transmission cycle in which there are data packets that are not successfully transmitted, or a transmission cycle in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission cycle in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

[0276] It should be understood that the division of the units in the above device is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. And the units in the device can all be implemented in the form of software calling through processing elements; they can also be all implemented in the form of hardware; some units can also be implemented in the form of software calling through processing elements, and some units can be implemented in the form of hardware. For example, each unit can be a separately established processing element, or it can be integrated in a certain chip of the device. In addition, it can also be stored in the memory in the form of a program, and called and executed by a certain processing element of the device. The function of the unit. In addition, all or part of these units can be integrated together, or they can be implemented independently. The processing element described here can also be a processor, which can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each unit above can be implemented by an integrated logic circuit of hardware in the processor element or in the form of software calling through a processing element.

[0277] In one example, the unit in any of the above devices may be one or more integrated circuits configured to implement the above method, such as one or more application specific integrated circuits (ASIC), or one or more digital singnal processors (DSP), or one or more field programmable gate arrays (FPGA), or a combination of at least two of these integrated circuit forms. For another example, when the unit in the device can be implemented in the form of a processing element scheduler, the processing element can be a processor, such as a general-purpose central processing unit (CPU), or other processors that can call programs. For another example, these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0278] The above unit for receiving may be an interface circuit of the device, used to receive signals from other devices. For example, when the device is implemented in the form of a chip, the receiving unit is an interface circuit of the chip used to receive signals from other chips or devices. The above unit for sending may be an interface circuit of the device, used to send signals to other devices. For example, when the device is implemented in the form of a chip, the sending unit is an interface circuit of the chip used to send signals to other chips or devices.

[0279] See also Fig.11 , is a schematic diagram of the structure of a network device provided in an embodiment of the present application, and the network device (or base station) can be applied to Figure 1 In the system architecture shown, the functions of the source network device or the target network device in the above method embodiment are executed. The network device 110 may include one or more DUs 1101 and one or more CUs 1102. The DU 1101 may include at least one antenna 11011, at least one radio frequency unit 11012, at least one processor 11013 and at least one memory 11014. The DU 1101 part is mainly used for receiving and transmitting radio frequency signals and converting radio frequency signals to baseband signals, as well as part of baseband processing. CU1102 may include at least one processor 11022 and at least one memory 11021.

[0280] The CU 1102 part is mainly used for baseband processing, controlling network equipment, etc. The DU 1101 and CU 1102 can be physically set together or physically separated, that is, a distributed base station. The CU 1102 is the control center of the network equipment, which can also be called a processing unit, and is mainly used to complete the baseband processing function. For example, the CU 1102 can be used to control the network equipment to execute the operation process of the network equipment in the above method embodiment.

[0281] In addition, optionally, the network device 110 may include one or more radio frequency units, one or more DUs, and one or more CUs. The DU may include at least one processor 11013 and at least one memory 11014, the radio frequency unit may include at least one antenna 11011 and at least one radio frequency unit 11012, and the CU may include at least one processor 11022 and at least one memory 11021.

[0282] In one example, the CU1102 may be composed of one or more boards, and the multiple boards may jointly support a wireless access network (such as a 5G network) with a single access indication, or may respectively support wireless access networks with different access standards (such as an LTE network, a 5G network, or other networks). The memory 11021 and the processor 11022 may serve one or more boards. In other words, a memory and a processor may be separately set on each board. It may also be that multiple boards share the same memory and processor. In addition, necessary circuits may be provided on each board. The DU1101 may be composed of one or more boards, and the multiple boards may jointly support a wireless access network (such as a 5G network) with a single access indication, or may respectively support wireless access networks with different access standards (such as a 5G network, or other networks). The memory 11014 and the processor 11013 may serve one or more boards. In other words, a memory and a processor may be separately set on each board. It may also be that multiple boards share the same memory and processor. In addition, necessary circuits may also be provided on each board.

[0283] Fig.11 The network device shown is capable of implementing various processes involving a source network device or a target network device in the above-illustrated method embodiment. Fig.11 The operations and / or functions of each module in the network device shown are respectively for implementing the corresponding processes in the above method embodiments. For details, please refer to the description in the above method embodiments. To avoid repetition, the detailed description is appropriately omitted here.

[0284] The terms "system" and "network" in the embodiments of the present application can be used interchangeably. "At least one" refers to one or more, and "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B, which can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following (single)" or its similar expression refers to any combination of these items, including any combination of single (single) or plural (single). For example, "at least one of A, B and C" includes A, B, C, AB, AC, BC or ABC. And, unless otherwise specified, the ordinal words such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, and are not used to limit the order, timing, priority or importance of multiple objects.

[0285] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0286] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0287] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0288] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0289] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A communication method, characterized in that: The method is applicable to a first communication device, where the first communication device is a target network device switched by a terminal device or a chip in the target network device, and the method includes: receiving N data packets of a first service and auxiliary information from a source network device switched by the terminal device, wherein the auxiliary information is used to indicate a transmission status of at least one data packet before the N data packets, and the N data packets include data packets cached by the source network device before the terminal device is switched and not yet sent to the terminal device; N is a positive integer; A transmission status of the at least one data packet is determined according to the auxiliary information.

2. The method according to claim 1, characterized in that The auxiliary information includes an identifier of a data packet that was not successfully transmitted before the N data packets; or, The auxiliary information includes an identifier of the first data packet that was not successfully transmitted before the N data packets, and transmission status information of the M data packets after the first data packet that was not successfully transmitted, and the last data packet of the M data packets is adjacent to the first data packet of the N data packets; M is a positive integer.

3. The method according to claim 1, characterized in that The auxiliary information is also used to indicate the corresponding relationship between the data packet and the transmission period.

4. The method according to claim 3, characterized in that The auxiliary information includes an identifier of a data packet included in at least one transmission cycle; or, The auxiliary information includes an identifier of a first data packet or a last data packet included in each transmission cycle in at least one transmission cycle, and the number of data packets included in each transmission cycle.

5. The method according to any one of claims 1 to 4, characterized in that The method further comprises: The data information that is allowed to be not successfully transmitted is received from the source network device, where the data information that is allowed to be not successfully transmitted is determined according to the lifetime of the first service.

6. The method according to claim 5, characterized in that The data information that is allowed to be not successfully transmitted includes at least one of the maximum number of data packets that are allowed to be continuously not successfully transmitted and the maximum number of transmission cycles that are allowed to be continuously not successfully transmitted; Among them, the unsuccessful transmission period is a transmission period in which there are data packets that are not successfully transmitted, or a transmission period in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission period in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

7. A communication method, characterized in that: The method is applicable to a second communication device, where the second communication device is a source network device switched by a terminal device or a chip in the source network device, and the method includes: Determine auxiliary information; N data packets of the first service and the auxiliary information are sent to the target network device to which the terminal device is switched; wherein the auxiliary information is used to indicate the transmission status of at least one data packet before the N data packets, and the N data packets include data packets cached by the source network device before the terminal device is switched and not yet sent to the terminal device; N is a positive integer.

8. The method according to claim 7, characterized in that The auxiliary information includes an identifier of a data packet that was not successfully transmitted before the N data packets; or, The auxiliary information includes an identifier of the first data packet that was not successfully transmitted before the N data packets, and transmission status information of the M data packets after the first data packet that was not successfully transmitted, and the last data packet of the M data packets is adjacent to the first data packet of the N data packets; M is a positive integer.

9. The method according to claim 7, characterized in that: The auxiliary information is also used to indicate the corresponding relationship between the data packet and the transmission period.

10. The method according to claim 9, characterized in that The auxiliary information includes an identifier of a data packet included in at least one transmission cycle; or, The auxiliary information includes an identifier of a first data packet or a last data packet included in each transmission cycle in at least one transmission cycle, and the number of data packets included in each transmission cycle.

11. The method according to any one of claims 7 to 10, characterized in that The method further comprises: Sending data information that is allowed to be not successfully transmitted to the target network device, wherein the data information that is allowed to be not successfully transmitted is determined according to the lifetime of the first service.

12. The method according to claim 11, characterized in that The data information that is allowed to be not successfully transmitted includes at least one of the maximum number of data packets that are allowed to be continuously not successfully transmitted and the maximum number of transmission cycles that are allowed to be continuously not successfully transmitted; Among them, the unsuccessful transmission period is a transmission period in which there are data packets that are not successfully transmitted, or a transmission period in which the number of data packets that are not successfully transmitted is greater than or equal to a first threshold, or a transmission period in which the amount of data that is not successfully transmitted is greater than or equal to a second threshold.

13. A communication device, characterized in that: Comprising modules for executing the method as claimed in any one of claims 1 to 6.

14. A communication device, characterized in that: Comprising means for executing the method as claimed in any one of claims 7 to 12.

15. A communication device, characterized in that: The method comprises a processor and a memory, wherein the processor and the memory are coupled, and the processor is used to implement the method according to any one of claims 1 to 6.

16. A communication device, characterized in that: The method comprises a processor and a memory, wherein the processor and the memory are coupled, and the processor is used to implement the method according to any one of claims 7 to 12.

17. A communication device, characterized in that: It includes a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor or send signals from the processor to other communication devices outside the communication device, and the processor is used to implement the method as described in any one of claims 1 to 6 through a logic circuit or executing code instructions.

18. A communication device, characterized in that: It includes a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor or send signals from the processor to other communication devices outside the communication device, and the processor is used to implement the method as described in any one of claims 7 to 12 through a logic circuit or executing code instructions.

19. A computer-readable storage medium, characterized in that: The storage medium stores a computer program or an instruction. When the computer program or the instruction is executed by the communication device, the method according to any one of claims 1 to 6 is implemented, or the method according to any one of claims 7 to 12 is implemented.

20. A communication system, characterized in that: It comprises the communication device as claimed in any one of claims 13, 15, and 17, and the communication device as claimed in any one of claims 14, 16, and 18.

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