WO2022156416A1 - 一种通信方法及装置 - Google Patents

一种通信方法及装置 Download PDF

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Publication number
WO2022156416A1
WO2022156416A1 PCT/CN2021/136654 CN2021136654W WO2022156416A1 WO 2022156416 A1 WO2022156416 A1 WO 2022156416A1 CN 2021136654 W CN2021136654 W CN 2021136654W WO 2022156416 A1 WO2022156416 A1 WO 2022156416A1
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Prior art keywords
data packets
network device
compressed data
terminal device
cache
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PCT/CN2021/136654
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English (en)
French (fr)
Inventor
姚楚婷
郭翱
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to US18/262,531 priority Critical patent/US20240080729A1/en
Priority to JP2023544402A priority patent/JP2024504158A/ja
Priority to BR112023014614A priority patent/BR112023014614A2/pt
Priority to EP21920790.9A priority patent/EP4271036A1/en
Priority to CN202180089312.2A priority patent/CN116982351A/zh
Publication of WO2022156416A1 publication Critical patent/WO2022156416A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/02—Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
    • H04W36/023—Buffering or recovering information during reselection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/04—Error control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/1607—Details of the supervisory signal
    • H04L1/1614—Details of the supervisory signal using bitmaps
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1867—Arrangements specially adapted for the transmitter end
    • H04L1/1874—Buffer management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/04—Protocols for data compression, e.g. ROHC
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/10—Flow control between communication endpoints
    • H04W28/14—Flow control between communication endpoints using intermediate storage
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0016—Hand-off preparation specially adapted for end-to-end data sessions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/22—Processing or transfer of terminal data, e.g. status or physical capabilities
    • H04W8/24—Transfer of terminal data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation
    • H04W80/02—Data link layer protocols

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a communication method and apparatus.
  • the uplink data compression (UDC) technology is introduced, and the packet data convergence protocol (PDCP) layer is implemented.
  • the UDC technology is mainly aimed at some data packets with a large number of repeated content, such as the data packets of the session initiation protocol (SIP) in the LTE network voice service (voice over long term evolution, VoLTE). Differences between packets to reduce the amount of data transferred.
  • SIP session initiation protocol
  • VoLTE voice over long term evolution
  • the terminal device When the terminal device is switched between cells, the terminal device will rebuild the PDCP layer, and the buffer corresponding to the UDC technology will also be reset (reset), and the buffer is used to compress data packets.
  • the base station may not correctly receive the data packets from the terminal equipment. For example, the terminal equipment sends multiple data packets, and some of the data packets may not be received by the base station, so the terminal equipment needs to retransmit. Since the buffer used for compressing the data packet is reset, when the terminal device retransmits the data packet, it needs to re-compress the data packet according to the reset buffer, that is, for the same data packet, the terminal device It may be necessary to compress twice, which undoubtedly increases the processing time of the terminal device and reduces the processing efficiency.
  • Embodiments of the present application provide a communication method and apparatus, which are used to reduce the number of times of compression of a terminal device, so as to correspondingly improve the processing efficiency of the terminal device.
  • a first communication method is provided, and the method can be executed by a terminal device, or executed by a chip system or other functional module, and the chip system or functional module can realize the function of the terminal device.
  • the method includes: sending M compressed data packets, where the M compressed data packets are obtained by compressing the M data packets based on a first buffer, where M is a positive integer; rebuilding the PDCP layer without resetting the first buffer ; Send N compressed data packets, the N compressed data packets are part or all of the M compressed data packets, and N is a positive integer less than or equal to M.
  • the terminal device does not reset the first cache when rebuilding the PDCP layer, then if the terminal device needs to retransmit the data packet, the terminal device can retransmit the compressed data packet obtained before , there is no need to compress the data packet again, thus reducing the number of times of compression of the data packet, reducing the processing time of the terminal device, and improving the processing efficiency. Moreover, since the workload of the terminal device is reduced, the power consumption of the terminal device is also reduced.
  • the method further includes: receiving a status report, where the status report is used to indicate a network device (a first network device or a second network device) Received compressed packets.
  • the status report indicates K compressed data packets.
  • the terminal device After the terminal device receives the status report, it can learn that the network device has received K compressed data packets.
  • the status report may be implemented through a bitmap (bitmap), the number of bits included in the bitmap may be M, and the M bits correspond to the M compressed data packets one-to-one.
  • the terminal device can quickly determine which compressed data packets are received by the network device.
  • the status report may include the sequence numbers of the compressed data packets that the network device has received, and/or include the sequence numbers of the compressed data packets that the network device has not received, so that the terminal device can identify which compressed data packets the network device has received. .
  • the N compressed data packets do not include the network device (the first network device or the first network device). 2.
  • the network device has received the compressed data packet. If the network device sends a status report to the terminal device, the status report indicates the compressed data packet that the network device has received, then the terminal device can no longer send the compressed data packet that the network device has received, but only needs to send the compressed data packet that the network device has not received. Received compressed packets. In this way, the amount of data retransmitted by the terminal device can be reduced, and the transmission overhead can be saved.
  • the N The data packet with the smallest sequence number among the compressed data packets is the data packet with the smallest sequence number among the data packets that were not successfully received by the network device.
  • the terminal device may retransmit the N compressed data packets to the network device (the first network device or the second network device).
  • the terminal device may send N compressed data packets in ascending order of the sequence numbers of the compressed data packets, starting from the first compressed data packet of the network device that is not determined to be successfully received.
  • the first compressed data packet in the N compressed data packets may be the first compressed data packet that is not successfully received by the first network device (or It is the compressed data packet with the smallest sequence number among the data packets that are not successfully received by the first network device), which can reduce the probability of packet loss by the first network device.
  • the method further includes: sending capability information, where the capability information is used to indicate support for continuing to use the first cache.
  • the network device (the first network device or the second network device) can determine whether the terminal device supports continuing to use the first cache according to the capability information. If the terminal device supports continuing to use the first cache, the network device may instruct the terminal device to continue using the first cache. If the terminal device does not support continuing to use the first cache, the network device may not instruct the terminal device to continue using the first cache or instruct the terminal device to re-use the first cache. Set the first cache. Alternatively, the terminal device may not send capability information, and the network device may determine whether to instruct the terminal device to continue to use the first cache according to other factors, or whether the terminal device continues to use the first cache may also be specified by a protocol.
  • the method further includes: receiving a handover command, where the handover command is used to instruct a cell to handover or rebuild the PDCP layer, and also to instruct to continue using the first buffer.
  • the handover command includes first indication information, and the first indication information may instruct to rebuild the PDCP layer, or instruct cell handover.
  • the handover command may further include second indication information, where the second indication information may indicate to continue to use the first buffer, or the second indication information may indicate that the first buffer is not reset when the PDCP is rebuilt.
  • the second indication information may not be included in the handover command, and the first network device may send the second indication information to the terminal device through other messages.
  • the protocol stipulates that the first buffer is continued to be used, or the protocol stipulates that the first buffer is not reset when the PDCP is rebuilt, and the first network device may not send the second indication information.
  • the first cache corresponds to a first radio bearer
  • the first radio bearer includes part or all of the radio bearers of the terminal device.
  • the terminal device configured with a radio bearer using the compression technology provided by the embodiment of the present application, it may be that one radio bearer corresponds to one cache, and the radio bearer and the cache have a one-to-one correspondence;
  • a bearer corresponds to a buffer, for example, space can be allocated for different radio bearers in the buffer, which can save the number of buffers.
  • sending M compressed data packets includes: sending the M compressed data packets to a first network device; sending N compressed data packets includes: sending the N compressed data packets to the first network device Compressed packets. If the cell handover process of the terminal device is a co-site handover process, that is, the terminal device accesses the first network device before the cell handover, and also accesses the first network device after the cell handover, then whether the terminal device is Sending M compressed data packets or sending N compressed data packets is both sent to the first network device.
  • sending the M compressed data packets includes: sending the M compressed data packets to a first network device, where the first network device is a network device accessed by the terminal device before performing cell handover;
  • Sending the N compressed data packets includes: sending the N compressed data packets to a second network device, where the first network device is a network device accessed by the terminal device after performing cell handover.
  • the cell handover process of the terminal device is a cross-site handover process, that is, the terminal device accesses the first network device before the cell handover, and the second network device after the cell handover, and the terminal device sends M
  • the number of compressed data packets may occur before the cell handover, and the sending of N compressed data packets may occur after the cell handover, so the terminal device may send M compressed data packets to the first network device, and send N compressed data packets to the second network device. Compressed packets.
  • a second communication method is provided, and the method can be executed by a first network device, or executed by a chip system or other functional module, and the chip system or functional module can implement the function of the first network device.
  • the first network device is an access network device, such as a base station.
  • the method includes: receiving K compressed data packets from a terminal device, the K compressed data packets are obtained by compressing the K data packets based on a first cache, and K is a positive integer; rebuilding the PDCP layer without resetting the second a cache, where the second cache is used by the first network device to decompress the data packets compressed based on the first cache.
  • the terminal device does not reset the first cache, and the corresponding first network device also does not reset the second cache corresponding to the first cache. If the terminal device needs to retransmit the data packet, the terminal device can retransmit the compressed data packet obtained before, without compressing the data packet again, which reduces the number of times of data packet compression and the processing of the terminal device. time and improve processing efficiency. Moreover, since the workload of the terminal device is reduced, the power consumption of the terminal device is also reduced. However, if the first network device does not reset the second cache, the states of the first cache and the second cache can be kept consistent. Therefore, the first network device can decompress the compressed data packets from the terminal device, reducing the size of the first network. The packet loss rate of the device.
  • the sequence numbers of the K data packets are not consecutive with the sequence numbers of the decompressed data packets by the first network device.
  • the sequence numbers between the sequence numbers of the K compressed data packets and the sequence numbers of the last data packet successfully decompressed by the first network device and delivered to the upper layer are discontinuous, indicating that the first network device has unreceived compressed data packets, but has not The received compressed data packets may affect the decompression of the K compressed data packets by the first network device.
  • the method further includes: sending the K compressed pieces to a second network device A data packet, the second network device is a network device accessed by the terminal device after cell handover, and the first network device is a network device accessed by the terminal device before cell handover.
  • the cell handover process of the terminal device is a cross-site handover process, that is, the terminal device accesses the first network device before the cell handover, and accesses the second network device after the cell handover.
  • the first network device since the terminal device performs cell handover, the first network device does not need to decompress the K compressed data packets, but can forward or send the K compressed data packets to the first network device through the interface between network devices (such as the Xn port). Two network devices, the K compressed data packets are processed by the second network device.
  • the method further Including: sending indication information to the second network device, where the indication information is used to indicate the content of the second cache, the content of the second cache is used to update the third cache, and the third cache is used for the first cache
  • Two network devices decompress the data packets compressed based on the first cache, the second network device is the network device that the terminal device accesses after performing cell handover, and the first network device is the terminal device The network device accessed before cell handover is performed.
  • the cell handover process of the terminal device is a cross-site handover process, that is, the terminal device accesses the first network device before the cell handover, and accesses the second network device after the cell handover.
  • the first network device can indicate the content of the second cache to the second network device
  • the second network device can update the third cache maintained by the second network device according to the content of the second cache, so that the state of the third cache and the first cache is Keep the same, so that the second network device can correctly decompress the compressed data packets from the terminal device.
  • the method further includes: sending a first message to the second network device, where the first message is used to inquire whether the terminal device is supported to continue using the first cache, the second network device is the network device accessed by the terminal device after the cell handover, the first network device is the network device accessed by the terminal device before the cell handover; the first network device receives from the second network device A second message, where the second message is used to indicate that the terminal device is supported to continue to use the first cache.
  • the cell handover process of the terminal device is a cross-site handover process, that is, the terminal device accesses the first network device before the cell handover, and accesses the second network device after the cell handover, then the first network device
  • the second network device may be inquired whether to support the terminal device to continue to use the first cache. For example, if the second network device does not support the terminal device to continue using the first cache, the first network device may configure the terminal device to reset the first cache so that the behavior of the terminal device is consistent with the behavior supported by the second network device.
  • the method further includes: sending a status report to the terminal device, the The status report is used to indicate that the K compressed data packets have been received by the first network device.
  • the method further includes: receiving N compressed data packets from the terminal device, the N The compressed data packets are part or all of the M compressed data packets, the K compressed data packets are part or all of the M compressed data packets, the sequence numbers of the M data packets are consecutive, and The M compressed data packets are obtained by compressing the M data packets based on the first cache, where M is a positive integer, N is a positive integer less than or equal to M, and K is a positive integer less than or equal to M.
  • the K compressed data packets are not included in the N compressed data packets.
  • the eighth optional embodiment of the second aspect In the embodiment of , the data packet with the smallest sequence number among the N compressed data packets is the data packet with the smallest sequence number among the data packets that are not successfully received by the first network device.
  • the method further includes: receiving capability information from the terminal device, where the capability information is used to indicate that the terminal device supports continuing to use the first cache.
  • the method further includes: sending a handover command to the terminal device, where the handover command is used to instruct a cell to switch or rebuild the PDCP layer, and also to instruct to continue using the first buffer.
  • the first cache corresponds to a first radio bearer
  • the first radio bearer includes part or all of the radio bearers of the terminal device.
  • a third communication method is provided, and the method can be executed by a second network device, or executed by a chip system or other functional module, and the chip system or functional module can implement the function of the second network device.
  • the second network device is an access network device, such as a base station.
  • the method includes: receiving K compressed data packets from a first network device, the K compressed data packets are obtained by compressing the K data packets based on a first cache, and the second network device is obtained after the terminal device performs cell handover Accessing network equipment, where the first network equipment is the network equipment that the terminal equipment accesses before performing cell handover; receiving indication information from the first network equipment, where the indication information is used to indicate the content of the second cache , the second cache is used by the first network device to decompress the data packets compressed based on the first cache; the third cache is updated according to the content of the second cache, and the third cache is used for all The second network device decompresses the data packet compressed based on the first cache.
  • the sequence numbers of the K data packets are not consecutive with the sequence numbers of the data packets that have been received by the second network device.
  • the method further includes: receiving N compressed data packets from the terminal device , the N compressed data packets are part or all of the M compressed data packets, the K compressed data packets are part or all of the M compressed data packets, and the M compressed data packets are The sequence numbers are consecutive, and the M compressed data packets are obtained by compressing the M data packets based on the first cache, where M is a positive integer, N is a positive integer less than or equal to M, and K is less than or equal to M positive integer.
  • the method further The method includes: receiving a first message from the first network device, where the first message is used to inquire whether to support the terminal device to continue to use the first cache; sending a second message to the first network device, the second The message is used to indicate that the terminal device is supported to continue to use the first buffer.
  • the fourth optional embodiment of the third aspect can be In an optional embodiment, the method further includes: sending a status report to the terminal device, where the status report is used to indicate that the second network device has received the K compressed data packets.
  • the K compressed data packets are not included in the N compressed data packets.
  • the data packet with the smallest sequence number among the N compressed data packets is the data packet with the smallest sequence number among the data packets not successfully received by the second network device.
  • the seventh optional embodiment of the third aspect corresponds to a first radio bearer, and the first radio bearer includes part or all of the radio bearers of the terminal device.
  • the method described in any one or more of the first aspect, the second aspect or the third aspect involves an uplink compression process.
  • a fourth communication method is provided, and the method can be executed by a first network device, or executed by a chip system or other functional module, and the chip system or functional module can implement the function of the first network device.
  • the first network device is an access network device, such as a base station.
  • the method includes: sending M compressed data packets to a terminal device, the M compressed data packets are obtained by compressing the M data packets based on the first cache, where M is a positive integer; rebuilding the PDCP layer without resetting the first cache.
  • the first network device does not reset the first cache in the case of rebuilding the PDCP layer, then if the first network device needs to retransmit the data packet, the first network device can retransmit the compressed data obtained before The packet can be retransmitted, and there is no need to compress the data packet again, which reduces the number of times of data packet compression, reduces the processing time of the first network device, and improves processing efficiency. Moreover, since the workload of the first network device is reduced, the power consumption of the first network device is also reduced.
  • the method further includes: sending indication information to a second network device, where the indication information is used to indicate the content of the first cache, The content of the first cache is used to update the second cache, and the second cache is used for the second network device to compress data packets, and the first network device is the terminal device that accesses before cell handover The second network device is the network device that the terminal device accesses after performing cell handover.
  • the method further includes: sending a first message to the second network device, where the The first message is used to inquire whether to support the terminal device to continue using the third cache, the first network device is the network device that the terminal device accesses before cell handover, and the second network device is the terminal A network device accessed by a device after performing cell handover; and receiving a second message from the second network device, where the second message is used to instruct the terminal device to continue using the third cache.
  • the method further includes: receiving a status report from the terminal device, where the status report is used to indicate the compression that the terminal device has received data pack.
  • the method further includes: sending N compressed data packets to the terminal device, the N The compressed data packets are part or all of the M compressed data packets, and N is a positive integer less than or equal to M.
  • the N compressed data packets do not include compressed data packets that have been received by the terminal device.
  • the sixth optional embodiment of the fourth aspect In the embodiment of , the data packet with the smallest sequence number among the N compressed data packets is the data packet with the smallest sequence number among the data packets that are not successfully received by the terminal device.
  • the method further includes: receiving capability information from the terminal device, where the capability information is used to indicate that the terminal device supports continuing to use a third cache, the third cache being used by the terminal device Decompress the data packets compressed based on the first cache or the second cache, the second cache is used for the second network device to compress the data packets, and the second network device is the terminal device to perform cell handover connected network devices.
  • the method further includes: sending a handover command to the terminal device, where the handover command is used to instruct the cell to switch or rebuild the PDCP layer, and also to instruct the terminal device to continue using the third buffer, so
  • the third cache is used for the terminal device to decompress the data packets compressed based on the first cache or the second cache
  • the second cache is used for the second network device to compress the data packets
  • the second cache is used to compress the data packets.
  • the network device is the network device that the terminal device accesses after performing cell handover.
  • a fifth communication method is provided, and the method can be executed by a second network device, or executed by a chip system or other functional module, and the chip system or functional module can implement the function of the second network device.
  • the second network device is an access network device, such as a base station.
  • the method includes: receiving indication information from a first network device, where the indication information is used to indicate content of a first cache, the first cache is used for the first network device to compress data packets, the second network The device is a network device accessed after the terminal device performs cell handover, and the first network device is a network device accessed by the terminal device before cell handover; the second cache is updated according to the content of the first cache, the The second cache is used for the second network device to compress the data packet.
  • the method further includes: receiving a first message from a first network device, where the first message is used to inquire whether the terminal is supported The device continues to use the third cache; and sends a second message to the first network device, where the second message is used to instruct the terminal device to continue using the third cache.
  • the method further includes: receiving a status report from the terminal device, the The status report is used to indicate the compressed data packets that the terminal device has received.
  • the method further includes: compressing the data packet according to the updated second cache, to obtain N compressed data packets; sending the N compressed data packets to the terminal device.
  • the N compressed data packets do not include compressed data packets that have been received by the terminal device.
  • the data packet with the smallest sequence number is the data packet with the smallest sequence number among the data packets that are not successfully received by the terminal device.
  • a sixth communication method is provided, and the method can be executed by a terminal device, or executed by a chip system or other functional module, and the chip system or functional module can realize the function of the terminal device.
  • the method includes: receiving K compressed data packets, the K compressed data packets are obtained by compressing the K data packets based on the first buffer; rebuilding the PDCP layer without resetting the third buffer; receiving N compressed data packets , the N compressed data packets are compressed based on the second cache, and K and N are both positive integers; based on the third cache, the K compressed data packets and the N compressed data Packet decompression, or, decompressing the N compressed data packets based on the third buffer.
  • receiving K compressed data packets includes: receiving the K compressed data packets from the first network device; receiving N compressed data packets, Including: receiving the N compressed data packets from the first network device.
  • the first cache and the second cache are the same cache, and the first cache maintained by the first network device.
  • receiving K compressed data packets includes: receiving the K compressed data packets from the first network device; receiving N compressed data packets, Including: receiving the N compressed data packets from a second network device, where the second network device is a network device accessed by the terminal device after cell handover, and the first network device is before the terminal device performs cell handover connected network device.
  • the first cache is maintained by the first network device, and the second cache is maintained by the Describe the maintenance of the second network device.
  • the K The sequence numbers of the data packets are not consecutive with the sequence numbers of the decompressed data packets of the terminal device.
  • the N The data packet with the smallest sequence number in the compressed data packet is the data packet with the smallest sequence number among the data packets that are not successfully received by the terminal device.
  • the method further The method includes: sending a status report, where the status report is used to indicate that the terminal device has received the K compressed data packets.
  • the K compressed data packets are not included in the N compressed data packets.
  • the method further The method includes: receiving a handover command, where the handover command is used for instructing cell handover or PDCP layer reconstruction, and also for instructing the terminal device to continue to use the third buffer.
  • the method further The method includes: sending capability information, where the capability information is used to indicate that the terminal device supports continuing to use the third buffer.
  • the method described in any one or more of the fourth aspect, the fifth aspect or the sixth aspect involves a downlink compression process.
  • a seventh communication method is provided, and the method can be executed by a terminal device, or executed by a chip system or other functional module, and the chip system or functional module can realize the function of the terminal device.
  • the method includes: receiving a handover command, where the handover command includes first indication information and second indication information, the first indication information is used to instruct the re-establishment of the PDCP layer or cell handover, and the second indication information is used to instruct the The terminal device continues to use the first cache, where the first cache is used for the terminal device to compress data packets; the PDCP layer is rebuilt, and the first cache is not reset.
  • the method further includes: receiving a status report, where the status report is used to indicate the compressed data packets that have been received by the network device.
  • the method further includes: starting from the first compressed data packet that is not determined to be successfully received, Send N compressed data packets in ascending order of the sequence numbers of the compressed data packets, where N is a positive integer.
  • sending the N compressed data packets in ascending order includes: performing integrity protection and encryption processing on the N compressed data packets; and sending the processed N compressed data packets.
  • the method further includes: sending capability information, where the capability information is used to indicate support for continuing to use the first cache.
  • the first cache corresponds to a first radio bearer
  • the first radio bearer includes part or all of the radio bearers of the terminal device.
  • an eighth communication method is provided, and the method can be executed by a first network device, or executed by a chip system or other functional module, and the chip system or functional module can implement the function of the first network device.
  • the first network device is an access network device, such as a base station.
  • the method includes: sending a handover command to a terminal device, where the handover command includes first indication information and second indication information, the first indication information is used to instruct the re-establishment of the PDCP layer or cell handover, and the second indication information is used for Instruct to continue to use the first cache, the first cache is used for the terminal device to compress data packets; the PDCP layer is rebuilt, and the second cache is not reset, and the second cache is used by the first network device to compress the data packets; The compressed data packets are decompressed based on the first cache.
  • the method further includes: sending K compressed data packets to the second network device, the K compressed data packets from the terminal device , the second network device is a network device accessed by the terminal device after performing cell handover, and the first network device is a network device accessed by the terminal device before performing cell handover.
  • the method further includes: sending indication information to a second network device, the The indication information is used to indicate the content of the second cache, the content of the second cache is used to update the third cache, and the third cache is used for the second network device to compress the data based on the first cache.
  • the packet is decompressed, the second network device is a network device accessed by the terminal device after cell handover, and the first network device is a network device accessed by the terminal device before cell handover.
  • the method further Including: sending a first message to the second network device, where the first message is used to inquire whether to support the terminal device to continue to use the first cache, and the second network device is the terminal device to perform cell handover The first network device is the network device accessed before the terminal device performs cell handover; the first network device receives a second message from the second network device, and the second network device The message is used to indicate that the terminal device is supported to continue to use the first buffer.
  • the method further includes: sending a status report to the terminal device, where the status report is used to indicate that the first network device has received compressed data packets.
  • the method further includes: receiving N compressed data packets from the terminal device, the N The data packet with the smallest sequence number among the compressed data packets is the data packet with the smallest sequence number among the data packets that are not successfully received by the first network device.
  • the N compressed data packets do not include the compressed data that has been received by the first network device Bag.
  • the method further The method includes: receiving capability information from the terminal device, where the capability information is used to indicate that the terminal device supports continuing to use the first cache.
  • the first The cache corresponds to a first radio bearer, and the first radio bearer includes part or all of the radio bearers of the terminal device.
  • the method described in the seventh aspect and/or the eighth aspect involves an uplink compression process.
  • a ninth communication method is provided, and the method can be executed by a first network device, or executed by a chip system or other functional module, and the chip system or functional module can realize the function of the first network device.
  • the first network device is an access network device, such as a base station.
  • the method includes: sending a handover command to a terminal device, where the handover command includes first indication information and second indication information, the first indication information is used to instruct the re-establishment of the PDCP layer or cell handover, and the second indication information is used for Instruct to continue to use the third cache, the third cache is used for the terminal device to decompress the data packets compressed based on the first cache or the second cache; the PDCP layer is rebuilt, and the first cache is not reset, so The first cache is used for the first network device to compress the data packets.
  • the method further includes: sending indication information to a second network device, where the indication information is used to indicate the content of the first cache, The content of the first cache is used to update the second cache, and the second cache is used for the second network device to compress data packets, and the first network device is the terminal device that accesses before cell handover The second network device is the network device that the terminal device accesses after performing cell handover.
  • the method further includes: sending a first message to the second network device, the The first message is used to inquire whether to support the terminal device to continue using the third cache, the first network device is the network device that the terminal device accesses before cell handover, and the second network device is the terminal A network device accessed by a device after performing cell handover; and receiving a second message from the second network device, where the second message is used to instruct the terminal device to continue using the third cache.
  • the method further includes: receiving a status report from the terminal device, where the status report is used to indicate the compression that the terminal device has received data pack.
  • the method further includes: starting from the first compressed data packet that is not determined to be successfully received, according to Send N compressed data packets to the terminal device in ascending sequence of the sequence numbers of the compressed data packets, where N is a positive integer.
  • the sequence numbers of the compressed data packets are in ascending order.
  • Sending the N compressed data packets to the terminal device in the sequence of the following steps includes: performing integrity protection and encryption processing on the N compressed data packets; and sending the processed N compressed data packets to the terminal device.
  • the N compressed data packets are The data packet with the smallest sequence number is the data packet with the smallest sequence number among the data packets that are not successfully received by the terminal device.
  • the seventh optional embodiment of the ninth aspect In the embodiment of , the N compressed data packets do not include the compressed data packets received by the terminal device.
  • the method further includes: receiving capability information from the terminal device, where the capability information is used to indicate that the terminal device supports continuing to use the third cache.
  • the method described in the ninth aspect involves a downlink compression process.
  • a tenth aspect provides a communication device.
  • the communication apparatus may be the terminal device described in any one of the above-mentioned first to ninth aspects.
  • the communication device has the functions of the above-mentioned terminal device.
  • the terminal equipment is, for example, a base station, or a baseband device in a base station.
  • the communication device includes a baseband device and a radio frequency device.
  • the communication apparatus includes a processing unit (sometimes also called a processing module) and a transceiver unit (sometimes also called a transceiver module).
  • the transceiver unit can realize the sending function and the receiving function.
  • the transceiver unit When the transceiver unit realizes the sending function, it can be called the sending unit (sometimes also called the sending module), and when the transceiver unit realizes the receiving function, it can be called the receiving unit (sometimes also called receiving module).
  • the sending unit and the receiving unit can be the same functional module, which is called a transceiver unit, and this functional module can realize the sending function and the receiving function; or, the sending unit and the receiving unit can be different functional modules, and the transceiver unit is the The collective name for functional modules.
  • the transceiver unit (or the sending unit) is configured to send M compressed data packets, the M compressed data packets are obtained by compressing the M data packets based on the first cache, and M is a positive integer;
  • the processing unit configured to rebuild the PDCP layer without resetting the first cache
  • the transceiver unit (or, the sending unit) is further configured to send N compressed data packets, where the N compressed data packets are part or all of the M compressed data packets, and N is less than or equal to M positive integer of .
  • the transceiver unit (or, the receiving unit) is configured to receive K compressed data packets, where the K compressed data packets are obtained by compressing the K data packets based on the first cache;
  • the processing unit configured to rebuild the PDCP layer without resetting the third cache
  • the transceiver unit (or, the receiving unit) is further configured to receive N compressed data packets, where the N compressed data packets are compressed based on the second cache, and K and N are both positive integers ;
  • the processing unit is further configured to decompress the K compressed data packets and the N compressed data packets based on the third cache, or decompress the N compressed data packets based on the third cache compression.
  • the transceiver unit (or, the receiving unit) is configured to receive a handover command, where the handover command includes first indication information and second indication information, and the first indication information is used to instruct the re-establishment of the PDCP layer or cell handover,
  • the second indication information is used to instruct the terminal device to continue to use the first cache, and the first cache is used for the terminal device to compress data packets;
  • the processing unit is configured to reconstruct the PDCP layer without resetting the first buffer.
  • the communication apparatus further includes a storage unit, and the processing unit is configured to be coupled to the storage unit and execute programs or instructions in the storage unit to enable the communication apparatus.
  • a communication device is provided.
  • the communication apparatus may be the first network device described in any one of the above-mentioned first to ninth aspects.
  • the communication apparatus has the function of the above-mentioned first network device.
  • the first network device is, for example, a base station, or a baseband device in a base station.
  • the communication device includes a baseband device and a radio frequency device.
  • the communication apparatus includes a processing unit (sometimes also called a processing module) and a transceiver unit (sometimes also called a transceiver module).
  • a processing unit sometimes also called a processing module
  • transceiver unit sometimes also called a transceiver module
  • the transceiver unit (or the receiving unit) is configured to receive K compressed data packets from the terminal device, the K compressed data packets are obtained by compressing the K data packets based on the first cache, and K is positive integer;
  • the processing unit is configured to rebuild the PDCP layer without resetting the second cache, where the second cache is used by the first network device to decompress the data packets compressed based on the first cache.
  • the transceiver unit (or the receiving unit) is configured to receive K compressed data packets from the first network device, where the K compressed data packets are obtained by compressing the K data packets based on the first cache, and the K compressed data packets are obtained by compressing the K data packets.
  • the second network device is a network device accessed by the terminal device after performing cell handover, and the first network device is a network device accessed by the terminal device before performing cell handover;
  • the transceiver unit (or the receiving unit) is further configured to receive indication information from the first network device, where the indication information is used to indicate the content of the second cache, and the second cache is used for the first network device.
  • a network device decompresses the data packet compressed based on the first cache;
  • the processing unit is configured to update a third cache according to the content of the second cache, and the third cache is used for the second network device to decompress the data packets compressed based on the first cache.
  • the transceiver unit (or the sending unit) is configured to send M compressed data packets to the terminal device, where the M compressed data packets are obtained by compressing the M data packets based on the first cache, where M is a positive integer ;
  • the processing unit is configured to reconstruct the PDCP layer without resetting the first buffer.
  • the transceiver unit (or, the receiving unit) is configured to receive indication information from the first network device, where the indication information is used to indicate the content of the first cache, and the first cache is used for the first network device compressing data packets, the second network device is a network device accessed by the terminal device after performing cell handover, and the first network device is a network device accessed by the terminal device before performing cell handover;
  • the processing unit is configured to update a second cache according to the content of the first cache, and the second cache is used for the second network device to compress data packets.
  • the transceiver unit (or, the sending unit) is configured to send a handover command to the terminal device, where the handover command includes first indication information and second indication information, and the first indication information is used to instruct to rebuild the PDCP layer or cell handover, the second indication information is used to instruct to continue to use the first buffer, and the first buffer is used for the terminal device to compress data packets;
  • the processing unit is configured to rebuild the PDCP layer without resetting the second cache, where the second cache is used by the first network device to decompress the data packets compressed based on the first cache.
  • the transceiver unit (or, the sending unit) is configured to send a handover command to the terminal device, where the handover command includes first indication information and second indication information, and the first indication information is used to instruct to rebuild the PDCP layer or Cell handover, the second indication information is used to instruct to continue to use the third buffer, and the third buffer is used for the terminal device to decompress the data packets compressed based on the first buffer or the second buffer;
  • the processing unit is configured to rebuild the PDCP layer without resetting the first cache, where the first cache is used for the first network device to compress data packets.
  • the communication apparatus further includes a storage unit, and the processing unit is configured to be coupled to the storage unit and execute programs or instructions in the storage unit to enable the communication apparatus.
  • a twelfth aspect provides a computer-readable storage medium for storing a computer program or instruction, which, when executed, enables the terminal device, the first network device or the second The method performed by the network device is implemented.
  • a thirteenth aspect provides a computer program product comprising instructions which, when run on a computer, cause the methods of the above aspects to be implemented.
  • FIG. 1 is a schematic diagram of a compression and decompression process of a data packet in an LTE system
  • FIG. 2 is a schematic diagram of a data packet transmission process between a terminal device and a base station when a cell handover occurs in the terminal device in the LTE system;
  • 3 and 4 are schematic diagrams of two application scenarios of the embodiments of the present application.
  • FIG. 5 is a schematic diagram of a UDC technology involved in an embodiment of the application.
  • Fig. 6 is the composition schematic diagram of the count value of the data packet
  • FIG. 7 is a flowchart of a first communication method provided by an embodiment of the present application.
  • FIG. 8 is a schematic diagram of a terminal device retransmitting part of a compressed data packet in an embodiment of the present application
  • FIG. 9 is a schematic diagram of a terminal device compressing a data packet in an embodiment of the present application.
  • FIG. 10 is a flowchart of a second communication method provided by an embodiment of the present application.
  • FIG. 11 is a flowchart of a third communication method provided by an embodiment of the present application.
  • FIG. 13 is a schematic block diagram of a communication apparatus provided by an embodiment of the present application.
  • FIG. 14 is a schematic block diagram of a terminal device provided by an embodiment of the present application.
  • FIG. 15 is a schematic block diagram of a network device provided by an embodiment of the present application.
  • a terminal device is a device with a wireless transceiver function, which may be a fixed device, a mobile device, a handheld device (such as a mobile phone), a wearable device, a vehicle-mounted device, or a wireless device (such as a built-in wireless device in the above-mentioned device). , communication modules, modems, or circuitry, etc.).
  • the terminal device is used to connect people, things, machines, etc., and can be widely used in various scenarios, such as but not limited to the following scenarios: cellular communication, device-to-device communication (device-to-device, D2D), vehicle-to-everything (vehicle to everything, V2X), machine-to-machine/machine-type communications (M2M/MTC), Internet of things (internet of things, IoT), virtual reality (virtual reality, VR) , Augmented reality (AR), industrial control (industrial control), unmanned driving (self driving), telemedicine (remote medical), smart grid (smart grid), smart furniture, smart office, smart wear, smart transportation , terminal equipment for smart city, drone, robot and other scenarios.
  • the terminal equipment may sometimes be referred to as user equipment (UE), a terminal, an access station, a UE station, a remote station, a wireless communication device, a user equipment, or the like.
  • the network devices in the embodiments of the present application include, for example, access network devices and/or core network devices.
  • the access network device is a device with a wireless transceiver function, and is used to communicate with the terminal device.
  • the access network equipment includes, but is not limited to, a base transceiver station (BTS), a Node B (Node B), an evolved Node B (eNodeB/eNB, or gNodeB/gNB), a transceiver point (transmission reception point, TRP), 3rd generation partnership project (3GPP) subsequent evolution base station, wireless fidelity (wireless fidelity, WiFi) system access node, wireless relay node, wireless backhaul node, etc.
  • BTS base transceiver station
  • Node B Node B
  • eNodeB/eNB evolved Node B
  • gNodeB/gNB gNodeB/gNB
  • TRP transmission reception point
  • 3GPP 3rd generation partnership project
  • the base station may be: a macro base station, a micro base station, a pico base station, a small base station, a relay station, and the like. Multiple base stations may support the aforementioned networks of the same access technology, or may support the aforementioned networks of different access technologies.
  • a base station may contain one or more co-sited or non-co-sited transmission and reception points.
  • the network device may also be a wireless controller, a centralized unit (centralized unit, CU), and/or a distributed unit (distributed unit, DU) in a cloud radio access network (cloud radio access network, CRAN) scenario.
  • the network device can also be a server, a wearable device, or a vehicle-mounted device.
  • a network device in a vehicle to everything (V2X) technology can be a road side unit (RSU).
  • the following description will be given by taking the access network device as a base station as an example.
  • the multiple network devices in the communication system may be base stations of the same type, or may be base stations of different types.
  • the base station can communicate with the terminal equipment, and can also communicate with the terminal equipment through the relay station.
  • a terminal device can communicate with multiple base stations in different access technologies.
  • the core network equipment is used to implement functions such as mobility management, data processing, session management, policy and charging.
  • the names of devices implementing core network functions in systems with different access technologies may be different, which are not limited in this embodiment of the present application.
  • the core network equipment includes: an access and mobility management function (AMF), a session management function (SMF), or a user plane function (UPF) Wait.
  • AMF access and mobility management function
  • SMF session management function
  • UPF user plane function
  • the communication device for implementing the function of the network device may be a network device, or a device capable of supporting the network device to realize the function, such as a circuit system, and the device may be installed in the network device.
  • the technical solutions provided by the embodiments of the present application are described by taking the device for realizing the function of the network device being a network device as an example.
  • the number of nouns means “singular nouns or plural nouns", that is, “one or more”. "At least one” means one or more, and “plurality” means two or more. "And/or”, which describes the relationship of the associated objects, indicates that there can be three kinds of relationships, for example, A and/or B, it can indicate that A exists alone, A and B exist at the same time, and B exists alone, where A, B can be singular or plural.
  • the character “/" generally indicates that the associated objects are an "or” relationship. For example, A/B, means: A or B.
  • At least one item(s) below or similar expressions thereof refer to any combination of these items, including any combination of single item(s) or plural items(s).
  • at least one of a, b, or c means: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, c Can be single or multiple.
  • first and second mentioned in the embodiments of this application are used to distinguish multiple objects, and are not used to limit the size, content, order, timing, application scenario, priority, or importance of multiple objects. degree, etc.
  • first cache and the second cache may be the same cache or different caches, and this name does not indicate the difference in content, priority, application scenario or importance of the two caches. .
  • FIG. 1 shows the process of data packet compression and decompression in the LTE system.
  • the PDCP and RLC in the upper two lines refer to the PDCP layer and the RLC layer of the sender. Taking the buffer size of 2 data packets as an example, each dashed box represents the content of the cache. In addition, there are pictures in the dashed box. The box of "/" represents the preset information included in the cache. Each packet is compressed based on what the current cache contains.
  • the PDCP and RLC in the lower two rows in FIG. 1 refer to the PDCP layer and the RLC layer at the receiving end.
  • the RLC layer In AM mode, because the RLC layer supports the data retransmission mechanism, although the sender sends the compressed data packets in order, the compressed data packets received by the receiver may be out of sequence.
  • the RLC layer at the receiving end sorts the received compressed data packets, and then delivers the sorted compressed data packets to the PDCP layer.
  • the receiving order of the RLC layer at the receiving end for compressed data packet 1, compressed data packet 2, compressed data packet 3 and compressed data packet 4 is compressed data packet 3, compressed data packet 4, compressed data packet 2 and compressed data packet Packet 1, then after receiving the compressed data packet 1, the RLC layer sorts the 4 compressed data packets, and then submits the 4 compressed data packets to the PDCP layer in the normal order, and the PDCP layer receives the 4 compressed data packets. Then, the four compressed data packets are decompressed through the UDC protocol stack in turn. After that, the receiving end receives the compressed data packet 5, the RLC layer of the receiving end submits the compressed data packet 5 to the PDCP layer, and the PDCP layer decompresses the compressed data packet 5.
  • the receiving end receives compressed data packet 6, compressed data packet 7, and compressed data packet 8, but the receiving end receives the three compressed data packets in the order of compressed data packet 8, compressed data packet 7, and compressed data packet 6.
  • the RLC layer at the receiving end sorts the three compressed data packets, and then submits the sorted three compressed data packets to the PDCP layer.
  • the PDCP layer receives the three compressed data packets, The three compressed data packets are decompressed sequentially through the UDC protocol stack.
  • the PDCP layer decompresses the compressed data packet 1 according to the preset information included in the compression cache, and the PDCP layer decompresses the compressed data packet 2 according to the preset information included in the compression cache and the compression
  • the sequence numbers of the data packets (or, the sequence numbers of the compressed data packets) appearing in FIG. 1 are the sequence numbers (sequence numbers, SN) of the PDCP layer, or the sequence numbers can also be understood as the count (count (count) of the PDCP layer of the data packets). )value.
  • the PDCP layer at the receiving end will receive the compressed data packets in order to ensure that the buffer of the receiving end and the buffer of the sending end are aligned, so as to realize sequential decompression.
  • the radio link control (RLC) layer of the base station is rebuilt. If the RLC layer has received out-of-order compressed data packets, or the RLC layer still has If the data packet has not been received, the RLC layer will no longer wait to receive the compressed data packet that has not been received, but will deliver the received compressed data packet to the PDCP layer.
  • the RLC layer of the base station receiving end
  • the RLC layer will compress the data packets. Packets 3, 4, 5, 7 are delivered to the PDCP layer.
  • the compressed data packet 0 has been received and successfully decompressed by the RLC, and the data packet 0 obtained by decompressing the compressed data packet 1 has been delivered to the PDCP layer.
  • the PDCP layer decompresses these compressed data packets.
  • the PDCP layer decompresses the compressed data packet 3 it needs to update the cache according to the decompression result of the compressed data packet 2, so that the compressed data packet 3 can be decompressed successfully.
  • the PDCP layer since the PDCP layer does not receive the compressed data packet 2, the PDCP layer will fail to decompress the compressed data packet 3. Similarly, the PDCP layer will also fail to decompress the compressed data packet 4, 5, and 7, and the PDCP layer will discard it.
  • the RLC layer of the base station will send a hybrid automatic repeat request (HARQ)-acknowledgement (ACK) information to the terminal device.
  • HARQ hybrid automatic repeat request
  • ACK acknowledgement
  • the RLC layer of the base station An acknowledgment (ACK) is sent to the end device.
  • the RLC layer has not received the compressed data packet 1 when the reconstruction occurs, so the RLC layer will not send the ACK of the compressed data packet 1 to the terminal device.
  • the terminal device After the terminal device (transmitter) completes the cell handover, it can retransmit the compressed data packet to the base station, for example, the terminal device retransmits the compressed data packet sequentially from the first compressed data packet that has not received an ACK. For example, if the terminal device receives the ACKs of the compressed data packets 3, 4, 5, and 7, but does not receive the ACKs of the compressed data packets 1, 2, and 6, the terminal device will retransmit the compressed data packets 1 to 7. The terminal device will rebuild the PDCP layer during the cell handover process, and also reset the terminal device's cache corresponding to the UDC and the UDC protocol stack, etc., then the terminal device will re-compress the data packet according to the reset cache.
  • the compressed data packets 1 to 7 previously sent by the terminal device to the base station are all obtained by compressing the corresponding data packets according to the cache before the reset. At this time, the terminal device will re-compress these data packets according to the reset cache. Compression is performed to obtain compressed data packets 1 to 7, and the terminal equipment sends these compressed data packets to the base station. It can be seen that for the same data packet, the terminal device needs to perform two compressions. The multiple compression process obviously increases the processing time of the terminal device, especially in the case of a large number of data packets, which will greatly reduce the processing efficiency of the terminal device.
  • UDC technology currently exists only in the LTE system, and a new radio (new radio, NR) system has not been introduced yet. Whether UDC technology can be used in NR systems is still inconclusive.
  • the embodiments of the present application provide a communication method, and through the method provided by the embodiments of the present application, a data compression technology (such as the UDC technology) based on a cache can be applied in an NR system.
  • the terminal device does not reset the first cache when rebuilding the PDCP layer, then if the terminal device needs to retransmit the data packet, the terminal device can retransmit the compressed data packet obtained before, that is, Yes, there is no need to compress the data packets again, which reduces the number of times of compression of the data packets, reduces the processing time of the terminal device, and improves the processing efficiency.
  • the workload of the terminal device is reduced, the power consumption of the terminal device is also reduced.
  • the terminal device can also process data normally without resetting the cache, which reduces the workload of the terminal device and also reduces the power consumption of the terminal device.
  • LTE systems for example, common LTE systems or Internet of Vehicles, such as vehicle to everything (V2X), LTE-V, etc.
  • NR systems for example, it can be applied to ordinary NR systems or Internet of Vehicles, such as V2X, NR-V, etc., or can also be applied to other similar communication systems or next-generation communication systems.
  • FIG. 3 is an application scenario of the embodiment of the present application.
  • a network device and a terminal device are included.
  • the network device for example, works in an evolved universal mobile communication system terrestrial radio access (evolved UMTS terrestrial radio access, E-UTRA) system, or works in an NR system.
  • the terminal equipment accesses the network equipment before and after the cell handover.
  • FIG. 4 is another application scenario of the embodiment of the present application.
  • 4 includes two network devices and one terminal device.
  • network device 1 is a network device accessed by the terminal device before cell handover
  • network device 2 is a network device accessed by the terminal device after cell handover.
  • the network device 1 or the network device 2 for example, works in the evolved Universal Mobile Communication System terrestrial radio access (evolved UMTS terrestrial radio access, E-UTRA) system, or works in the NR system, and the network device 1 and the network The system in which the device 2 works can be the same or different.
  • E-UTRA evolved Universal Mobile Communication System terrestrial radio access
  • the network device in FIG. 3 or FIG. 4 is, for example, a base station.
  • the network device corresponds to different devices in different systems, for example, in a 4G system, it may correspond to an eNB, and in a 5G system, it corresponds to a network device in 5G, such as a gNB.
  • the network equipment can also be a mixed networking equipment of LTE network equipment and NR network equipment, forming a mixed radio-dual connectivity (MR-DC) with terminal equipment.
  • MR-DC mixed radio-dual connectivity
  • FIG. 3 and FIG. 4 both take the network device being a base station as an example.
  • the network device may also be a device such as an RSU.
  • VoLTE/voice over new radio (VoNR) phone calls or data Internet access such as initiating live broadcasts, playing games and surfing the Internet), etc.
  • VoIP Voice over new radio
  • the terminal device At the beginning of accessing the network, the terminal device generally needs to report to the base station whether it supports the capability of data compression.
  • the base station may decide whether to configure the terminal device with relevant parameters of data compression (for example, configure the corresponding bearer to support the UDC function and its activation state) according to the service initiated by the user.
  • the terminal device can use the UDC method when performing uplink transmission, such as initiating a VoLTE/VoNR phone call or initiating a live broadcast or playing a real-time game.
  • the terminal device can use the method provided by the embodiment of the present application to perform UDC, which can reduce or even avoid packet loss caused by uplink data compression, and save power consumption caused by repeated compression.
  • the method provided by this embodiment of the present application may also be used to reduce or even avoid packet loss caused by downlink data compression.
  • the embodiments of the present application do not limit the communication between the network device and the terminal device, but may also be the communication between the network device and the network device, or the communication between the terminal device and the terminal device.
  • UDC is that the terminal device acts as the sender to compress the data packet, and the network device acts as the receiver to decompress the data packet, and the compression and decompression are performed based on the sender and the receiver jointly maintaining the same cache state.
  • the cache state may refer to the content included in the cache (or, in other words, the information included in the cache).
  • the sender compresses the data packet, it compresses based on the current state of the cache. After the compression is successful, the sender will put the original information of the current compressed data packet before compression into the cache from the back end of the cache for caching. renew.
  • the information of the previous data packet may not be included in the cache during compression, and the sender may compress based on preset information, such as a pre-made dictionary.
  • a pre-made dictionary For example, referring to FIG. 5 , the cache includes "abc", and "abc" is, for example, a pre-made dictionary.
  • the sender needs to compress the data packet "def”, it can compress based on "abc”. After compressing the data packet "def", the compressed data packet 1 is obtained, and the sender can put "def" from the back end of the cache into the cache.
  • the sender needs to compress the data packet "ghijkl”, which can be compressed based on the "abcdef" in the buffer, that is to say, the compression is performed each time based on the entire content in the buffer.
  • a compressed data packet 2 is obtained, and the sender can put the data packet "ghijkl” from the backend of the cache into the cache. Due to the limited storage space of the buffer, according to the principle of first in first out (FIFO), "abcd” will be squeezed out of the buffer, so if the sender needs to compress other data packets, it will be Compression is done based on "efghijkl” included in the cache.
  • FIFO first in first out
  • the receiving end After receiving the compressed data packet 1, it can decompress the compressed data packet 1 based on the prefabricated dictionary "abc” in the cache to obtain the data packet "def”, and remove the data packet "def” from the back of the cache. side into the cache.
  • the receiving end After receiving the compressed data packet 2, the receiving end can decompress the compressed data packet 2 based on the information "abcdef” in the cache, obtain the data packet "ghijkl”, and put the data packet "ghijkl” from the back end of the cache into the cache, Then "abcd” is squeezed out of the cache. It can be seen that the cache status of the receiver and the cache status of the sender are always consistent, so that the receiver can decompress correctly.
  • the sequence numbers of the data packets before compression may be the same.
  • the first compressed data packet can be obtained by compressing the first data packet, and the sequence number of the first compressed data packet is the same as that of the first data packet;
  • the second compressed data packet can be obtained by compressing the second data packet,
  • the sequence number of the second compressed data packet is the same as the sequence number of the second data packet.
  • the technical solutions provided by the various embodiments of this application can be applied to the transmission of data radio bearers (DRBs) of UM/AM, or the transmission of signaling radio bearers (SRBs). , or the transmission of a certain quality of service flow (QoS flow) in the DRB.
  • DRBs data radio bearers
  • SRBs signaling radio bearers
  • QoS flow quality of service flow
  • each data packet has a number corresponding to the PDCP layer.
  • the number of a data packet at the PDCP layer can be composed of two parts, the two parts are the sequence number (sequence number, SN) and the hyper frame number (hyper frame number, HFN), these two parts together constitute the data packet.
  • the number, or the count value of the packet Referring to FIG. 6 , it is a schematic diagram of the composition of the count value of the data packet.
  • the sequence number of the data packet described in the embodiments of the present application may refer to the sequence number of the data packet or the count value of the data packet.
  • FIG. 7 is a flowchart of the method.
  • the method is applied to the network architecture shown in FIG. 3 as an example.
  • the terminal device described below is, for example, a terminal device in the network architecture shown in FIG. 3
  • the first network device described below is, for example, a network device in the network architecture shown in FIG. 3 .
  • the terminal device sends capability information to a first network device, and correspondingly, the first network device receives capability information from the terminal device.
  • the terminal device may send the capability information to the first network device during the random access process, or the terminal device may send the capability information to the first network device after the random access is successful.
  • the capability information may indicate the capability of the terminal device, for example, the capability information indicates that the terminal device can support UDC.
  • the capability information may indicate that the continuation of the use of the first buffer is supported, which indicates that the terminal device supports the function of continuing to use the first buffer (this function may also be referred to as buffer continue), or indicates that the continuation of the use of the first buffer is not supported. cache.
  • the buffer continue can be understood as not resetting the buffer corresponding to the data compression/decompression function when the PDCP layer is rebuilt.
  • the capability information can also indicate that the first buffer is not supported when the PDCP layer is rebuilt, or indicate that the first buffer is not reset when the PDCP layer is rebuilt.
  • the PDCP layer does not support not resetting the first cache.
  • the capability information may also indicate other capabilities of the terminal device, such as indicating the number of antennas supported by the terminal device, etc., which is not limited.
  • the first buffer is maintained by the terminal device and is used for compressing the data packet, or in other words, the terminal device may compress the data packet based on the first buffer.
  • the first network device can determine whether the terminal device supports continuing to use the first cache according to the capability information. If the terminal device supports continuing to use the first cache, the first network device may instruct the terminal device to continue using the first cache; if the terminal device does not support continuing to use the first cache, the first network device may not instruct the terminal device to continue using the first cache or Instruct the terminal device to reset the first cache. Alternatively, the terminal device may not send the capability information, and the first network device may determine whether to instruct the terminal device to continue using the first cache according to other factors, or whether the terminal device continues to use the first cache can also be specified by the protocol, so S701 is optional A step of.
  • the terminal device sends M compressed data packets to the first network device, and correspondingly, the first network device receives K compressed data packets from the terminal device.
  • M is a positive integer
  • K is a positive integer less than or equal to M.
  • the K compressed data packets may be part or all of the M compressed data packets, or the K compressed data packets may be a subset of the M compressed data packets.
  • the reason why the first network device receives K compressed data packets instead of receiving M compressed data packets is to consider the situation of packet loss. received correctly.
  • the sequence numbers of the K compressed data packets may or may not be consecutive.
  • the sequence numbers of the K compressed data packets and the sequence numbers of the data packets that have been successfully decompressed by the first network device are discontinuous.
  • the M compressed data packets are compressed data packets 1 to 7, and the K compressed data packets are compressed data packets 3, 4, 5, and 7, the sequence numbers of the K compressed data packets are discontinuous, and the first network The compressed data packet with the largest sequence number that the device has successfully decompressed is compressed data packet 0, then the sequence number between the sequence numbers of the K compressed data packets and the last data packet that the first network device has successfully decompressed and submitted to the upper layer is also the same. Discontinuous.
  • the M compressed data packets are compressed data packets 1 to 7, and the K compressed data packets are compressed data packets 3, 4, 5, and 6, the sequence numbers of the K compressed data packets are consecutive, and the first network device
  • the compressed data packet with the highest sequence number that has been successfully decompressed is compressed data packet 0, and the sequence numbers of the K compressed data packets and the sequence numbers of the data packets that have been successfully decompressed by the first network device are not consecutive.
  • the M compressed data packets are obtained by the terminal device compressing the M data packets based on the first cache, and the compressed data packets and the data packets are in a one-to-one correspondence.
  • the first cache is a cache for the terminal device to compress the data packet.
  • the terminal device may use the UDC technology to compress the data packet based on the first cache.
  • the first cache corresponds to, for example, the first radio bearer, and the first radio bearer may include all or part of the radio bearers of the terminal device, and the radio bearer is, for example, DRB or SRB.
  • the first buffer corresponds to, for example, one or more QoS flows in the DRB.
  • the terminal device before sending the M compressed data packets, the terminal device has not sent the compressed data packets to the first network device, then before the terminal device compresses the M compressed data packets, the first cache includes, for example, a pre-made dictionary, that is, the first cache Filled with pre-made dictionaries.
  • the terminal device compresses the data packet 1 in the M data packets based on the pre-made dictionary to obtain the compressed data packet 1 .
  • the terminal device updates the first cache based on the content of the data packet 1, and then compresses the data packet 2 in the M data packets based on the updated first cache to obtain the compressed data packet 2, and so on until the M compressed data packets are obtained. data pack. See also Figure 5 for an example of this process.
  • the first network device may send feedback information of the K compressed data packets to the terminal device to indicate that the first network device has received the K compressed data packets. For example, every time the RLC layer of the first network device receives a compressed data packet, it can send an ACK of the compressed data packet to the terminal device, then the first network device can send a total of K ACKs to the terminal device, and K ACKs correspond to K compressed data packets. For data packets, after the terminal device receives K ACKs, it can learn that the first network device has received K compressed data packets.
  • the PDCP layer of the first network device may also send a status report to the terminal device, where the status report may indicate the compressed data packets received by the first network device.
  • the status report may indicate There are K compressed data packets, and after the terminal device receives the status report, it can learn that the first network device has received K compressed data packets.
  • the status report may be implemented through a bitmap (bitmap), the number of bits included in the bitmap may be M, and the M bits correspond to the M compressed data packets one-to-one.
  • the bit corresponding to the compressed data packet is set to "1"; if the first network device does not receive a compressed data packet, the corresponding bit of the compressed data packet is set to "0", so that the terminal device can quickly determine which compressed data packets have been received by the first network device.
  • the status report may include the sequence numbers of the compressed data packets that have been received by the first network device, and/or include the sequence numbers of compressed data packets that have not been received by the first network device, so that the terminal device can identify the first network device. Which compressed packets were received.
  • the terminal device can process the compressed data packet accordingly before sending it. For example, the terminal device performs integrity protection and encryption processing on the compressed data packet (such as corresponding processing at the PDCP layer), and delivers the processed compressed data packet to the bottom layer of the terminal device (such as the RLC layer, media access control (media access control) control, MAC) layer, or physical layer, etc.), and then the bottom layer of the terminal device sends the processed compressed data packets.
  • the terminal equipment sends M compressed data packets, and the terminal equipment that will be involved in the following sends N compressed data packets, all of which can be in a similar manner, which is not repeated here.
  • the first network device sends a handover command to the terminal device, and correspondingly, the terminal device receives the handover command from the first network device.
  • the handover command includes first indication information, and the first indication information may instruct to rebuild the PDCP layer, or instruct cell handover.
  • the handover command may further include second indication information, where the second indication information may indicate to continue to use the first buffer, or the second indication information may indicate that the first buffer is not reset when the PDCP is rebuilt.
  • the terminal device can continue to use the first buffer in the case of rebuilding the PDCP layer, and if the handover command does not include the second indication information, the terminal device is rebuilding the PDCP layer.
  • the first buffer will not continue to be used.
  • the terminal device will reset the first buffer in the case of rebuilding the PDCP layer.
  • the second indication information indicates whether to reset the first buffer when re-establishing the PDCP.
  • the value of the second indication information indicates whether to reset the first buffer when re-establishing the PDCP.
  • the second indication information may not be included in the handover command, and the first network device may send the second indication information to the terminal device through other messages. If this is the case, the first network device can send the second indication information to the terminal device before S703, or send the second indication information to the terminal device after S703, or the first network device can also send the handover command to the terminal device at the same time. and second indication information.
  • the terminal device receives the second indication information, the terminal device can continue to use the first buffer under the condition of rebuilding the PDCP layer, and if the terminal device does not receive the second indication information, the terminal device is rebuilding the PDCP layer. In the case of the PDCP layer, the first buffer will not continue to be used, for example, the terminal device may reset the first buffer in the case of rebuilding the PDCP layer.
  • the first network device also supports continuing to use the second cache.
  • the second cache corresponds to the first cache, and is maintained by the first network device.
  • the first network device may, according to the second cache, pair the compressed data packets (or, in other words, data compressed based on the first cache) on the compressed data packets obtained based on the first cache. package) to decompress.
  • the first network device may support continuing to use the second cache, or may not support continuing to use the second cache, regardless of whether the first network device supports continuing to use the second cache, Since the first network device does not send the second indication information, the first network device will not continue to use the second cache in the case of rebuilding the PDCP layer, but will reset the second cache to be consistent with the behavior of the terminal device.
  • the protocol stipulates that the first buffer is continued to be used, or the protocol stipulates that the first buffer is not reset when the PDCP is rebuilt, and the first network device may not send the second indication information.
  • the network device may determine according to the protocol to continue to use the second buffer when rebuilding the PDCP layer, and the terminal device may also determine according to the protocol to continue to use the first buffer when rebuilding the PDCP layer.
  • the terminal device may also rebuild the PDCP layer in other situations, so S703 is an optional step.
  • the terminal device rebuilds the PDCP layer, and does not reset the first cache.
  • the PDCP layer can be rebuilt.
  • the terminal device can also rebuild the PDCP layer triggered by other events than the cell handover, so S703 is an optional step.
  • the terminal device may not reset the first buffer when rebuilding the PDCP layer.
  • the terminal device may reset the first cache when rebuilding the PDCP layer.
  • the terminal device resetting the first cache includes clearing the content of the first cache, and adding a pre-made dictionary to the cleared first cache.
  • the content of the prefabricated dictionary is related to, for example, services. When the services performed by the devices are different, the prefabricated dictionaries may be the same or may be different. Alternatively, the content of the prefabricated dictionary may also be related to other factors, which are not specifically limited, and will not be described in detail later. In the embodiment of the present application, the terminal device does not reset the first cache when rebuilding the PDCP layer as an example.
  • the first network device rebuilds the PDCP layer, and does not reset the second cache.
  • the first network device will also rebuild the PDCP layer.
  • the terminal equipment accesses the first network equipment before and after the cell handover. For example, the terminal equipment switches from the first cell provided by the first network equipment to the first network equipment provided by the first network equipment. Second district. If the first network device determines to continue to use the second cache, the first network device does not reset the second cache when rebuilding the PDCP layer. However, if the first network device determines not to continue to use the second cache, the first network device may reset the second cache when rebuilding the PDCP layer. The first network device resets the second cache, for example, including clearing the content of the second cache, and adding a pre-made dictionary to the cleared second cache.
  • the pre-made dictionary used for resetting the first cache and the pre-made dictionary used for resetting the second cache may be the same.
  • the embodiment of the present application takes as an example that the first network device does not reset the second cache when rebuilding the PDCP layer.
  • S704 may occur before S705, or may occur after S705, or may also occur simultaneously with S705.
  • the terminal device sends N compressed data packets to the first network device, and correspondingly, the first network device receives N compressed data packets from the terminal device.
  • the N compressed data packets are part or all of the M compressed data packets, for example, N is an integer less than or equal to M.
  • the terminal device After the terminal device performs cell handover, or after the terminal device completes the reconstruction of the PDCP layer, but does not switch the network device, it may retransmit N compressed data packets to the first network device.
  • the terminal device sends N compressed data packets in ascending order of sequence numbers of the compressed data packets, starting from the first compressed data packet of the first network device that is not determined to be successfully received.
  • the first compressed data packet in the N compressed data packets (or, in other words, the compressed data packet with the smallest sequence number among the N compressed data packets), may be the first compressed data packet that is not successfully received by the first network device (or It is the compressed data packet with the smallest sequence number among the data packets that are not successfully received by the first network device).
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7
  • the N compressed data packets are compressed data packets 1 to 7.
  • the first compressed data packet in the N compressed data packets is the compressed data packet 1
  • the compressed data packet 1 is the first compressed data packet that is not successfully received by the first network device.
  • the terminal device is equivalent to retransmitting M compressed data packets, which can improve the success rate of the first network device in obtaining the compressed data packets.
  • the terminal device may not accept the compressed data packet received by the first network device. Then, it is only necessary to send the compressed data packets not received by the first network device. In this case, the N compressed data packets may not include the compressed data packets that have been received by the first network device.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7
  • the status report sent by the first network device to the terminal device indicates the K compressed data packets data packets
  • the N compressed data packets sent by the terminal device such as compressed data packets 1, 2, and 6, and the compressed data packets 3, 4, 5, and 7, the terminal device can no longer send, which can reduce the number of retransmissions by the terminal device.
  • Data volume saving transmission overhead.
  • the M compressed data packets sent by the PDCP layer of the terminal device are, for example, compressed data packets 1 to 7, and the PDCP layer of the first network device has received compressed data packets 3, 4, 5, and 7, and The compressed data packets 1, 2, and 6 are not received, and the PDCP layer of the terminal device also sends compressed data packets 0 to the first network device before sending M compressed data packets, and the PDCP layer of the first network device receives the compressed data packets.
  • the PDCP layer of the first network device submits the data packet 0 to the upper layer of the PDCP layer, for example, the service data adaptation protocol (service data adaptation protocol, SDAP) layer.
  • the PDCP layer of the first network device sends a status report to the PDCP layer of the terminal device, and the status report indicates that the first network device has received the compressed data packets 3 , 4 , 5 , and 7 .
  • the status report is implemented by a bitmap.
  • the bitmap can include 7 bits.
  • the bitmap is 1011100. From the low bit to the high bit, it corresponds to the compressed data packet 1 to the compressed data packet 7.
  • the first network device receives the compressed data packets 3 and 4. , 5, and 7, the bits corresponding to these compressed data packets take the value "1", and the first network device does not receive the compressed data packets 1, 2, and 6, and the corresponding bits of these compressed data packets take the value "0".
  • the PDCP layer of the terminal device resends the compressed data packets 1, 2, and 6 to the first network device, and does not need to resend the compressed data packets 3, 4, 5, and 7, so as to save uplink transmission resources. .
  • 1 to 7 in the first row in FIG. 9 represent 7 PDCP service data units (SDUs), that is, 7 data packets, that is, 1 to 7 in the first row represent 7 data packets to be compressed .
  • the second row represents the compressed data packets 1 to 7 obtained by the terminal device after compressing the data packets 1 to 7 based on the first cache.
  • the third row represents the encrypted data packets 1 to 7 obtained by encrypting the compressed data packets 1 to 7 in the second row according to the first encryption method.
  • the terminal device can send the seven encrypted data packets to the first network device.
  • An encryption method is the encryption method corresponding to the first cell that the terminal device accesses before performing the cell handover.
  • the fourth row represents the encrypted data packets 1 to 7 obtained by encrypting the compressed data packets 1 to 7 in the second row according to the second encryption method.
  • the terminal device can send the seven encrypted data packets to the first network device.
  • the second encryption mode is the encryption mode corresponding to the second cell that the terminal device accesses after performing cell handover. It can be seen from Figure 9 that the terminal device only performs the compression process of these data packets once. If these compressed data packets need to be retransmitted, it is only necessary to encrypt the obtained compressed data packets according to the corresponding encryption method after cell switching. That is, there is no need to compress the data packets again, which reduces the compression process of the terminal device and correspondingly improves the processing efficiency of the terminal device.
  • the first network device may decompress the K compressed data packets. Since the sequence numbers of the K compressed data packets are not consecutive with the sequence numbers of the data packets that have been successfully decompressed by the first network device, the first network device may fail to decompress the K compressed data packets, and the first network device may discard the decompression failure. of K compressed packets.
  • the terminal device will then send N compressed data packets to the first network device. Since the terminal device has not received the status report, the compressed data packet with the smallest sequence number among the N compressed data packets is one of the compressed data packets not successfully received by the first network device.
  • the compressed data packet with the smallest sequence number, and the sequence numbers of N data packets are consecutive, for example, M compressed data packets are compressed data packets 1 to 7 compressed data packets, and K compressed data packets are compressed data packets 3, 4, 5, 7.
  • the N compressed data packets are compressed data packets 1 to 7. In this way, even if the first network device discards K compressed data packets, since the terminal device will send N compressed data packets again, and the N compressed data packets will include K compressed data packets, the first network device can still obtain K compressed data packets Compressed packets.
  • the first network device since the first network device has obtained compressed data packets 1 to 7, and the first network device has correctly decompressed the compressed data packet 0 before, the state of the second cache is determined according to the data packet 0 , then the first network device can correctly decompress the compressed data packets 1 to 7 based on the unreset second cache.
  • the first network device may not decompress the K compressed data packets, but wait for N compressed data packets from the terminal device.
  • the PDCP layer may have a deduplication function. For example, for the compressed data packet 3, the first network device has already received it, and the first network device has not discarded it. If the compressed data packet 3 is included in the N compressed data packets, the first network device After receiving the compressed data packet 3 in the N compressed data packets, the device discards the compressed data packet 3 and continues to store the previously received compressed data packet 3.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7,
  • the N compressed data packets are compressed data packets 1 to 7.
  • the first network device will discard the compressed data packets 3, 4, 5, and 7 of the N received compressed data packets.
  • the second cache is not reset
  • the compressed data packets 3, 4, 5, and 7 stored by the first network device are the same as the compressed data packets 3, 4, 5, and 7 discarded by the first network device.
  • a network device can still correctly decompress the K compressed data packets 3, 4, 5, and 7, and the compressed data packets 1, 2, and 6 in the N compressed data packets, In this way, the packet loss rate of the first network device can be reduced.
  • the N compressed data packets sent by the terminal device may no longer include K compressed data packets.
  • the K compressed data packets are decompressed, and the K compressed data packets are discarded because the decompression fails, and the terminal device no longer sends the K compressed data packets, which will cause the first network device to fail to obtain the K compressed data packets. It may affect the decompression of other compressed data packets by the first network device. Therefore, after receiving the K compressed data packets, if the first network device sends a status report to the terminal device, the first network device may not decompress the K compressed data packets, but wait for N compressed data packets from the terminal device.
  • the first network device Since the terminal device does not repeatedly send data packets with the same sequence number, the first network device also does not need to use the deduplication function.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7,
  • the N compressed data packets are compressed data packets 1, 2, and 6.
  • a network device Based on the unreset second cache, a network device can correctly decompress the K compressed data packets 3, 4, 5, and 7, and the N compressed data packets 1, 2, and 6.
  • the first network device decompresses the N compressed data packets based on the second cache, or the first network device decompresses the N compressed data packets and the K compressed data packets based on the second cache.
  • the first network device decompresses the N compressed data packets based on the second cache.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7,
  • the N compressed data packets are compressed data packets 1 to 7. Then, the first network device decompresses the compressed data packets 1 to 7 based on the second cache.
  • the first network device decompresses the N compressed data packets and the K compressed data packets based on the second cache.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7,
  • the N compressed data packets are compressed data packets 1, 2, and 6, then
  • the first network device decompresses the compressed data packets 1 to 7 based on the second cache, and the compressed data packets 1 to 7 are the union of the K compressed data packets and the N compressed data packets.
  • the compression times of the terminal device can be reduced, and the processing efficiency of the terminal device can be improved. If the first network device sends a status report to the terminal device, the amount of data sent by the terminal device can also be reduced, thereby saving transmission overhead. Moreover, since neither the first cache of the terminal device nor the second cache of the first network device is reset, in the case where the first network device does not send a status report to the terminal device, regardless of whether the first network device is receiving K compressed data packets Whether or not to decompress the K compressed data packets afterward, the first network device can obtain M compressed data packets, which reduces the amount of packet loss.
  • the foregoing describes the case where the terminal device and the first network device do not reset the cache. If the second indication information received by the terminal device indicates that the first cache is not to be used, or the protocol stipulates that the first cache is not to be used, the terminal device will not continue to use the first cache.
  • the first cache may be reset when the PDCP layer is rebuilt, and the second cache may also be reset for the first network device.
  • the processing methods of the terminal device and the first network device in this case are briefly described as follows.
  • the PDCP layer of the first network device has received compressed data packets 3 , 4 , 5 , and 7 , but has not received compressed data packets 1 , 2 , and 6 .
  • the compressed data packet 0 is a compressed data packet that has been received and successfully decompressed by the PDCP layer, and the PDCP layer decompresses the compressed data packet 0 to obtain the data packet 0 .
  • the PDCP reconstruction instruction can trigger the decompression of these compressed data packets. If the PDCP layer fails to decompress the compressed data packets 3, 4, 5, and 7, then the PDCP layer fails to decompress the compressed data packets.
  • a PDCP re-establishment indication can trigger the PDCP layer to drop out-of-order compressed packets (there is a special case if the packet from the sender is an uncompressed packet , the data packets do not need to be discarded even if they are out of sequence), that is, the PDCP layer does not decompress the compressed data packets 3, 4, 5, and 7, but directly discards the compressed data packets 3, 4, 5, and 7.
  • the solution of directly discarding the out-of-order compressed data packets can reduce the number of decompression times at the receiving end, improve processing efficiency, save energy consumption, and avoid wasting resources for ineffective decompression processing.
  • the RLC layer of the first network device will send ACK information to the terminal device.
  • the RLC layer of the first network device will send ACK to the terminal device.
  • the feedback report may indicate either the data packets that the first network device has not received, or the data packets that have not been successfully decompressed by the first network device.
  • the terminal device may retransmit the compressed data packet to the first network device after the cell handover is completed, or after the PDCP layer reconstruction is completed. For example, if the terminal device receives ACKs for compressed data packets 0, 3, 4, 5, and 7, but does not receive ACKs for compressed data packets 1, 2, and 6, the terminal device will retransmit compressed data packets 1 to 7. During the cell handover process, the terminal device will rebuild the PDCP layer and also reset the first cache, and then the terminal device will re-compress the data packet according to the reset first cache.
  • the compressed data packets 1 to 7 previously sent by the terminal device to the first network device are all obtained by compressing the data packets 1 to 7 according to the first cache before reset.
  • the installed first cache compresses data packets 1 to 7 again to obtain compressed data packets 1 to 7, and the terminal device sends these compressed data packets to the first network device. It can be seen that if the first buffer is not used continuously, the terminal device needs to perform two compressions for the same data packet.
  • the first network device may indicate whether to continue to use the first cache, and the first network device may indicate whether to continue to use the first cache according to specific circumstances. For example, for terminal devices with lower capabilities, the first network The device may not instruct to continue to use the first cache, or may instruct not to continue to use the first cache to meet the capability requirements of the terminal device; for another example, for scenarios with high latency requirements, the first network device may instruct to continue to use the first cache , the terminal device only needs to compress once, which saves the processing time of the terminal device, thereby reducing the transmission delay of the data packet. It can be seen that the solutions in the embodiments of the present application are relatively flexible.
  • the application scenario of the embodiment shown in FIG. 7 is a co-site scenario, that is, the terminal device accesses the same network device before and after the handover.
  • the second communication method provided by the embodiment of the present application is introduced.
  • the method can be applied to the network architecture shown in FIG. 4 .
  • FIG. 10 is a flowchart of the method.
  • the terminal device accesses the first network device before performing the cell handover, and accesses the second network device after the cell handover, which can be understood as the first network device provided by the terminal device from the first network device.
  • the cell is switched to the second cell provided by the second network device, and the first network device and the second network device are different network devices.
  • the terminal device described below is, for example, the terminal device in the network architecture shown in FIG. 4
  • the first network device described below is, for example, the network device 1 in the network architecture shown in FIG. 4
  • the second network described below is, for example, the network device 2 in the network architecture shown in FIG. 4 .
  • a terminal device sends capability information to a first network device, and correspondingly, the first network device receives capability information from the terminal device.
  • S1001 For more content of S1001, reference may be made to S701 in the embodiment shown in FIG. 7 .
  • the terminal device sends M compressed data packets to the first network device, and correspondingly, the first network device receives K compressed data packets from the terminal device.
  • M is a positive integer
  • K is a positive integer less than or equal to M.
  • the first network device may send feedback information of the K compressed data packets to the terminal device, for example, the RLC layer of the first network device may send K ACKs to the terminal device .
  • the first network device may also send a status report of the K compressed data packets to the terminal device, where the status report indicates the compressed data packets received by the first network device, for example, indicates K compressed data packets.
  • the first network device may not send the status report of the K compressed data packets to the terminal device.
  • S1002 For more content of S1002, reference may also be made to S702 in the embodiment shown in FIG. 7 .
  • the first network device sends the first message to the second network device, and correspondingly, the second network device receives the first message from the first network device.
  • the first message may be used to inquire whether to support the terminal device to continue to use the first buffer after handover, or the first message may be used to inquire whether to support the terminal device not to reset the first buffer when rebuilding the PDCP layer.
  • the first cache is a cache maintained by the terminal device for compressing data packets. If the first cache is reset, the content of the third cache maintained by the second network device for decompression also needs to be reset. After the state, such as filling the pre-made dictionary in the third cache.
  • the third cache is maintained by the second network device, and the second network device may decompress the data packets compressed based on the first cache according to the third cache.
  • the first cache, the second cache, and the third cache are all corresponding.
  • the first cache is maintained by the terminal device, and the terminal device compresses the data packets according to the first cache;
  • the second cache is maintained by the first network device, and the terminal device is performing
  • the first network device is accessed before the cell handover, and the first network device can decompress the compressed data packets (data packets compressed based on the first cache) from the terminal device based on the second cache;
  • the third cache is stored by the second network
  • the terminal equipment accesses the second network equipment after the cell handover, and the second network equipment can decompress the compressed data packets (data packets compressed based on the first buffer) from the terminal equipment based on the third cache.
  • the first message is a handover request (handover request) message.
  • handover request message includes inquiry information, and the inquiry information can be used to inquire whether the second network device supports the terminal device to continue using the first cache.
  • the first message may also be other messages.
  • the second network device sends a second message to the first network device, and correspondingly, the first network device receives the second message from the second network device.
  • the second message may indicate that the terminal equipment that supports continues to use the first buffer, or indicates that the terminal equipment that does not support continues to use the first buffer.
  • the second message may instruct the supporting terminal device not to reset the first buffer when rebuilding the PDCP layer, or instruct the non-supporting terminal device not to reset the first buffer when rebuilding the PDCP layer.
  • the second message is a handover request acknowledgement message. It can be understood that the handover request acknowledgement message includes third indication information, and the third indication information can instruct the supporting terminal equipment to continue to use the first buffer, or indicate that the terminal equipment is not supported.
  • the third indication information may instruct the supporting terminal device not to reset the first buffer when rebuilding the PDCP layer, or instruct the non-supporting terminal device not to reset the first buffer when rebuilding the PDCP layer.
  • the second message may also be another message.
  • the first network device may not need to know whether the second network device supports the terminal device to continue to use the first cache, or the first network device may also learn whether the second network device supports the terminal device to continue to use the first cache by other means. Therefore, S1003 and S1004 are optional steps.
  • the first network device sends a handover command to the terminal device, and correspondingly, the terminal device receives the handover command from the first network device.
  • the handover command may instruct the terminal equipment to perform cell handover, or instruct the PDCP to perform re-establishment.
  • the switching command may further include information for instructing the terminal device to continue to use the first cache or not to continue to use the first cache.
  • the terminal device rebuilds the PDCP layer, and does not reset the first cache.
  • the first network device rebuilds the PDCP layer, and does not reset the second cache.
  • S1007 For more content of S1007, reference may be made to S705 in the embodiment shown in FIG. 7 .
  • the first network device sends the second cached content to the second network device, and correspondingly, the second network device receives the second cached content from the first network device.
  • the first network device may send indication information to the second network device.
  • the indication information may also be referred to as fourth indication information, and the fourth indication information may indicate the content of the second cache.
  • the fourth indication information includes the content of the second cache (eg, according to the size of the second cache, a common configuration of the size of the second cache is 2k, 4k, or 8k bytes), or the fourth indication information does not include the second cache content, but the second network device may determine the content of the second cache according to the fourth indication information.
  • the first network device may send fourth indication information to the second network device, and if the second network device does not support the terminal device to continue to use the first cache, the first network device The network device may not need to send the fourth indication information to the second network device.
  • S1008 and S1003 may also be the same message.
  • the first network device sends the second cached content to the second network device, and may implicitly or explicitly ask the second network device whether to support the terminal device to continue using the first cache.
  • the second network device updates the third cache according to the content of the second cache.
  • the second network device can put the content of the second cache into the third cache, or replace the original content in the third cache with the content of the second cache, so that the state of the third cache is consistent with the state of the second cache, which is also equivalent to The state of the third buffer before compressing a certain data packet is made consistent with the state of the first buffer when the data packet is decompressed.
  • the first network device sends K compressed data packets to the second network device, and correspondingly, the second network device receives K compressed data packets from the first network device.
  • the first network device since the terminal device performs cell handover, the first network device does not need to decompress the K compressed data packets, but can pass the K compressed data packets through an interface between network devices (eg, Xn port)
  • the K compressed data packets are forwarded or sent to the second network device, and the K compressed data packets are processed by the second network device.
  • the first network device may not send the K compressed data packets to the second network device, that is, the first network device only forwards the successfully decompressed data packets to the second network device, for example, according to the embodiment shown in FIG.
  • the N compressed data packets will include K compressed data packets.
  • a network device does not send K compressed data packets to the second network device, and the second network device may also receive K compressed data packets from the terminal device. Therefore, S1110 is an optional step.
  • the second network device may send a status report of the K compressed data packets to the terminal device.
  • the status report indicates the compressed data packets that have been received by the second network device, for example, indicates K compressed data packets, or the second network device may not send the status report to the terminal device. That is, in this embodiment of the present application, the first network device and/or the second network device may send status reports of K compressed data packets to the terminal device.
  • the status report of K compressed data packets may be received from the first network device, or the status report of K compressed data packets may be received from the second network device, or the status report of K compressed data packets may also be received from the first network device. and the second network device both receive status reports for the K compressed data packets.
  • neither the first network device nor the second network device may send the status report of the K compressed data packets to the terminal device, and the terminal device will not receive the status report of the K compressed data packets.
  • the first network device may also receive other compressed data packets from the terminal device, and the first network device has successfully decompressed these compressed data packets, then the first network device can decompress the data packets. Successful packets are also sent to the second network device.
  • the terminal device sends N compressed data packets to the second network device, and correspondingly, the second network device receives N compressed data packets from the terminal device.
  • the N compressed data packets are part or all of the M compressed data packets, for example, N is an integer less than or equal to M.
  • the terminal device can continue to send data packets to the second network device, so the terminal device will retransmit the N compressed data packets to the second network device.
  • S1011 For more content of S1011, reference may be made to S706 in the embodiment shown in FIG. 7 .
  • the foregoing describes the situation where the terminal device and the first network device do not reset the cache, and if the second indication information received by the terminal device indicates not to continue using the first cache, or the protocol stipulates not to continue to use the first cache, the terminal device will
  • the first buffer may be reset in the case of rebuilding the PDCP layer.
  • the second cache is also reset for the first network device in case of rebuilding the PDCP layer.
  • the processing methods of the terminal device and the first network device are introduced as follows.
  • the PDCP layer of the first network device when the PDCP layer of the first network device is rebuilt, it has received the compressed data packets 3, 4, 5, and 7, but has not yet received the compressed data packets 1, 2, and 6. After the PDCP layer receives the compressed data packets 3, 4, 5, and 7, the PDCP reconstruction instruction can trigger the decompression of these compressed data packets. If the PDCP layer fails to decompress the compressed data packets 3, 4, 5, and 7, then the PDCP layer fails to decompress the compressed data packets.
  • the layer will drop compressed packets 3, 4, 5, 7, or, a PDCP re-establishment indication can trigger the PDCP layer to drop out-of-order compressed packets (there is a special case if the packet from the sender is an uncompressed packet , the data packets do not need to be discarded even if they are out of sequence), that is, the compressed data packets 3, 4, 5, and 7 are not decompressed, but the compressed data packets 3, 4, 5, and 7 are directly discarded.
  • the solution of directly discarding out-of-order compressed data packets can reduce the number of decompression times, improve processing efficiency, save energy consumption, and avoid wasting resources for ineffective decompression processing.
  • the first network device only needs to send the decompressed correct data packets or the undiscarded out-of-order compressed data packets to the second network device, and does not need to send the decompressed or uncompressed compressed data packets to the second network device.
  • the RLC layer of the first network device will send ACK information to the terminal device.
  • the RLC layer of the first network device will send ACK to the terminal device.
  • the terminal device may retransmit the compressed data packet to the second network device after the cell handover is completed or after the PDCP layer reconstruction is completed. For example, if the terminal device receives ACKs for compressed data packets 0, 3, 4, 5, and 7, but does not receive ACKs for compressed data packets 1, 2, and 6, the terminal device will retransmit compressed data packets 1 to 7. During the cell handover process, the terminal device will rebuild the PDCP layer and also reset the first cache, and then the terminal device will re-compress the data packets according to the reset first cache.
  • the compressed data packets 1 to 7 previously sent by the terminal device to the second network device are all obtained by compressing the data packets 1 to 7 according to the first cache before the reset.
  • the installed first cache compresses data packets 1 to 7 again to obtain compressed data packets 1 to 7, and the terminal device sends these compressed data packets to the second network device. It can be seen that if the first buffer is not used continuously, the terminal device needs to perform two compressions for the same data packet.
  • the second network device decompresses the N compressed data packets based on the third cache, or the second network device decompresses the N compressed data packets and the K compressed data packets based on the third cache.
  • the N compressed data packets include K compressed data packets, for example, the second network device has not received K compressed data packets from the first network device, or although the second network device has received K compressed data packets from the first network device data packets, but the N compressed data packets include K compressed data packets, it can be understood that the second network device decompresses the N compressed data packets based on the third cache.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7, and the N compressed data packets are compressed data packets 1 to 7.
  • the second network device decompresses the compressed data packets 1 to 7 based on the third cache.
  • the N compressed data packets do not include K compressed data packets
  • the second network device receives K compressed data packets from the first network device, and the N compressed data packets do not include K compressed data packets, Then it can be understood that the second network device decompresses the N compressed data packets and the K compressed data packets based on the third cache.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7,
  • the N compressed data packets are compressed data packets 1, 2, and 6, then
  • the second network device decompresses the compressed data packets 1 to 7 based on the third cache, and the compressed data packets 1 to 7 are the union of the K compressed data packets and the N compressed data packets.
  • the compression times of the terminal device can be reduced, and the processing efficiency of the terminal device can be improved. If the first network device and/or the second network device sends a status report to the terminal device, the amount of data sent by the terminal device can also be reduced, thereby saving transmission overhead.
  • the third cache of the second network device can also be set according to the second cache, then the first and second network devices can In the case where no status report is sent to the terminal device, regardless of whether the second network device decompresses the K compressed data packets after receiving the K compressed data packets, or whether the second network device will receive the K compressed data packets , the second network device can obtain M compressed data packets, which reduces the amount of packet loss.
  • the embodiment shown in FIG. 7 and the embodiment shown in FIG. 10 both describe the compression process of the upstream data packet, for example, the UDC technology is used.
  • the embodiments of the present application also provide a compression process of downlink data packets, which will be introduced below.
  • FIG. 11 is a flowchart of the method, which involves a downlink data packet compression process.
  • the method is applied to the network architecture shown in FIG. 3 as an example.
  • the terminal device described below is, for example, a terminal device in the network architecture shown in FIG. 3
  • the first network device described below is, for example, a network device in the network architecture shown in FIG. 3 .
  • a terminal device sends capability information to a first network device, and correspondingly, the first network device receives capability information from the terminal device.
  • the capability information may indicate that the continued use of the third buffer is supported when PDCP re-establishment occurs, or that the continued use of the third buffer is not supported when PDCP re-establishment occurs; or, the capability information may indicate that the third buffer is not supported to be reset when the PDCP layer is rebuilt Cache, or indicate that the tertiary cache is not supported when the PDCP layer is rebuilt.
  • the third buffer is maintained by the terminal device and is used to decompress the data packet. In other words, the terminal device can decompress the data packet based on the third buffer. Compressed packets are decompressed.
  • the first network device can determine whether the terminal device supports continuing to use the third cache according to the capability information. If the terminal device supports continuing to use the third cache, the first network device can choose whether to instruct the terminal device to continue using the third cache when the handover occurs. If the terminal device does not support continuing to use the third cache, the first network device does not instruct the terminal to continue using the third cache. The device continues to use the third cache. Alternatively, the terminal device may not send the capability information, and the first network device may determine whether to instruct the terminal device to continue using the third cache according to other factors, or whether the terminal device continues to use the third cache can also be specified by the protocol, so S1101 is optional A step of.
  • S1101 For more content of S1101, reference may be made to S701 in the embodiment shown in FIG. 7 .
  • the first network device sends M compressed data packets to the terminal device, and correspondingly, the terminal device receives K compressed data packets from the first network device.
  • M is a positive integer
  • K is a positive integer less than or equal to M.
  • the K compressed data packets may be part or all of the M compressed data packets, or the K compressed data packets may be a subset of the M compressed data packets.
  • the M compressed data packets are obtained by the first network device compressing the M data packets based on the first cache (or, the first cache in this embodiment of the present application may also be referred to as the second cache).
  • the first cache is maintained by the first network device, and is used for the first network device to compress the data packets. For example, the first network device may use a downlink compression technology to compress the data packets based on the first cache.
  • the first network device may perform corresponding processing on the compressed data packet before sending.
  • the first network device performs integrity protection and encryption processing on the compressed data packet (for example, performs corresponding processing at the PDCP layer), and delivers the processed compressed data packet to the bottom layer of the first network device (for example, the RLC layer, the MAC layer, or physical layer, etc.), and then the processed compressed data packet is sent by the bottom layer of the first network device.
  • the first network device sends M compressed data packets, and the first network device (or, the second network device) to be involved in the following sends N compressed data packets, both of which can be in a similar manner, and will not be repeated here.
  • S701 For more content of S1102, reference may be made to S701 in the embodiment shown in FIG. 7, and the roles of “terminal device” and “first network device” in S701 may be interchanged during reference.
  • the first network device sends a handover command to the terminal device, and correspondingly, the terminal device receives the handover command from the first network device.
  • the handover command may instruct the terminal device to perform cell handover or PDCP layer re-establishment.
  • the handover command may further instruct the terminal device to continue using the third buffer when the PDCP is rebuilt, or instruct not to reset the third buffer when the terminal device re-establishes the PDCP.
  • S703 for more information on S1103, please refer to S703 in the embodiment shown in FIG. 7 .
  • the “first cache” maintained by the terminal device in S703 can be replaced with a “third cache”, and the first network The "second cache” maintained by the device is replaced with the "first cache”.
  • the terminal device rebuilds the PDCP layer, and does not reset the third cache.
  • the first network device rebuilds the PDCP layer, and does not reset the first cache.
  • the first network device sends N compressed data packets to the terminal device, and correspondingly, the terminal device receives N compressed data packets from the first network device.
  • the N compressed data packets are part or all of the M compressed data packets, for example, N is an integer less than or equal to M.
  • the first network device may send N compressed data packets in an ascending sequence of the sequence numbers of the compressed data packets, starting from the first compressed data packet of the terminal device that is not determined to be successfully received.
  • S706 for more information about S1106, please refer to S706 in the embodiment shown in FIG. 7 .
  • the roles of “terminal device” and “first network device” in S706 may be interchanged, and the “first network device” may be replaced
  • the roles of "cache” and "third cache” are reversed.
  • the terminal device decompresses the N compressed data packets based on the third cache, or the terminal device decompresses the N compressed data packets and the K compressed data packets based on the third cache.
  • the terminal device decompresses the N compressed data packets based on the third cache.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7,
  • the N compressed data packets are compressed data packets 1 to 7. Then, the terminal device decompresses the compressed data packets 1 to 7 based on the third cache.
  • the terminal device decompresses the N compressed data packets and the K compressed data packets based on the third cache.
  • the M compressed data packets are compressed data packets 1 to 7
  • the K compressed data packets are compressed data packets 3, 4, 5, and 7,
  • the N compressed data packets are compressed data packets 1, 2, and 6, then
  • the terminal device decompresses the compressed data packets 1 to 7 based on the third cache, and the compressed data packets 1 to 7 are the union of the K compressed data packets and the N compressed data packets.
  • the compression times of the first network device can be reduced, and the processing efficiency of the first network device can be improved. If the terminal device sends a status report to the first network device, the amount of data sent by the first network device can also be reduced, thereby saving transmission overhead. Moreover, since neither the third cache of the terminal device nor the first cache of the first network device is reset, in the case where the terminal device does not send a status report to the first network device, no matter what the Whether the K compressed data packets are decompressed, the terminal device can obtain M compressed data packets, which reduces the amount of packet loss.
  • the terminal device may reset the third buffer.
  • the first cache is also reset for the first network device.
  • the processing methods of the terminal device and the first network device reference may also be made to the description of the embodiment shown in FIG. The roles of the first network device" are reversed.
  • the first network device may indicate whether to continue to use the third cache, and then the first network device may indicate whether to continue to use the third cache according to specific circumstances. For example, for terminal devices with lower capabilities, the first network The device may not instruct to continue to use the third cache, or may instruct not to continue to use the third cache to meet the capability requirements of the terminal device; for another example, for scenarios with high latency requirements, the first network device may instruct to continue to use the third cache , the first network device only needs to compress once, which saves the processing time of the first network device, thereby reducing the transmission delay of the data packet. It can be seen that the solutions in the embodiments of the present application are relatively flexible.
  • the application scenario of the embodiment shown in FIG. 11 is a co-site scenario, that is, the terminal device accesses the same network device before and after the handover.
  • the fourth communication method provided by the embodiment of the present application is introduced.
  • the method can be applied to the network architecture shown in FIG. 4 .
  • FIG. 12 is a flowchart of the method, which still involves a downlink compression process.
  • the terminal device accesses the first network device before performing the cell handover, and accesses the second network device after the cell handover, and the first network device and the second network device are different network devices.
  • the terminal device described below is, for example, the terminal device in the network architecture shown in FIG. 4
  • the first network device described below is, for example, the network device 1 in the network architecture shown in FIG. 4
  • the second network described below The device is, for example, the network device 2 in the network architecture shown in FIG. 4 .
  • a terminal device sends capability information to a first network device, and correspondingly, the first network device receives capability information from the terminal device.
  • the first network device sends M compressed data packets to the terminal device, and correspondingly, the terminal device receives K compressed data packets from the first network device.
  • M is a positive integer
  • K is a positive integer less than or equal to M.
  • the K compressed data packets may be part or all of the M compressed data packets, or the K compressed data packets may be a subset of the M compressed data packets.
  • the M compressed data packets are obtained by the first network device compressing the M data packets based on the first cache.
  • the first cache is maintained by the first network device, and is used for the first network device to compress the data packets. For example, the first network device may use a downlink compression technology to compress the data packets based on the first cache.
  • S701 For more content of S1202, reference may be made to S701 in the embodiment shown in FIG. 7, and the roles of “terminal device” and “first network device” in S701 may be interchanged during reference.
  • the first network device sends the first message to the second network device, and correspondingly, the second network device receives the first message from the first network device.
  • the first message may be used to inquire whether to support the terminal device to continue using the third buffer, or the first message may be used to inquire whether to support the terminal device not to reset the third buffer when rebuilding the PDCP layer.
  • the third cache is a cache maintained by the terminal device for decompressing data packets, and if the third cache is reset, the content of the third cache maintained by the terminal device for decompression is the reset third cache After the state, such as the third cache will be filled with the pre-made dictionary.
  • the second network device maintains a second cache, and the second cache is used for the second network device to compress the data packets. For example, the second network device may compress the data packets according to the second cache.
  • the first cache, the second cache, and the third cache are all corresponding.
  • the first cache is maintained by the first network device.
  • the terminal device accesses the first network device before performing cell handover.
  • the first network device is based on the first cache.
  • the second cache is maintained by the second network device, the terminal device accesses the second network device after the cell handover, and the second network device can compress the data packets based on the second cache;
  • the third cache Maintained by the terminal device, the terminal device can decompress the compressed data packets from the first network device and/or the second network device based on the third cache, or the terminal device can decompress the compressed data packets based on the first cache according to the third cache.
  • the data packets are decompressed, and/or the data packets compressed based on the second cache are decompressed according to the third cache.
  • the first message is a handover request message.
  • the handover request message includes inquiry information, and the inquiry information can be used to inquire whether to support the terminal device to continue using the third cache, or to inquire whether to support the terminal device not to reset the PDCP layer when rebuilding the PDCP layer.
  • Third cache Alternatively, the first message may also be other messages.
  • the second network device sends the second message to the first network device, and correspondingly, the first network device receives the second message from the second network device.
  • the second message may indicate that the terminal device that supports continues to use the third buffer, or indicates that the terminal device that does not support continues to use the third buffer.
  • the second message is a handover request response message. It can be understood that the handover request response message includes third indication information, and the third indication information may indicate that the continued use of the third cache is supported, or the continued use of the third cache is not supported.
  • the second message may also be another message.
  • the first network device may not need to know whether the second network device supports the terminal device to continue to use the third cache, or the first network device may also learn whether the second network device supports the terminal device to continue to use the third cache by other means. Therefore, S1203 and S1204 are optional steps.
  • the first network device sends a handover command to the terminal device, and accordingly, the terminal device receives the handover command from the first network device.
  • the handover command may instruct the terminal equipment to perform cell handover.
  • S703 For more information about S1205, please refer to S703 in the embodiment shown in FIG. 7 .
  • the “first cache” maintained by the terminal device in S703 may be replaced with a “third cache”, and the first network The "second cache” maintained by the device is replaced with the "first cache”.
  • the terminal device rebuilds the PDCP layer, and does not reset the third cache.
  • the first network device rebuilds the PDCP layer, and does not reset the first cache.
  • the first network device sends the first cached content to the second network device, and accordingly, the second network device receives the first cached content from the first network device.
  • the first network device may send indication information to the second network device.
  • the indication information may also be referred to as fourth indication information, and the fourth indication information may indicate the content of the first cache.
  • the fourth indication information includes the content of the first cache (for example, according to the size of the first cache, the common configuration of the size of the content of the first cache is 2k, 4k, or 8k bytes), or the fourth indication information does not include the first cache. the cached content, but the second network device may determine the first cached content according to the fourth indication information.
  • S1208 and S1203 are the same message, the first network device sends the second cached content to the second network device, and can implicitly or explicitly ask the second network device whether to support the terminal device to continue to use the third cache.
  • the first network device may send fourth indication information to the second network device, and if the second network device does not support the terminal device to continue to use the third cache, the first network device The network device may not need to send the fourth indication information to the second network device, so S1208 is an optional step.
  • the second network device updates the second cache according to the content of the first cache.
  • the second network device can replace the original content in the second cache with the content in the first cache, so that the state of the second cache is consistent with the state of the first cache, which is also equivalent to making the state of the second cache before compressing a certain data packet the same as the state of the first cache.
  • the state of the third cache is consistent when the data packet is decompressed.
  • the first network device forwards the data packet from the core network device to the second network device, and correspondingly, the second network device receives the data packet from the first network device.
  • these data packets include data packets (SDUs) compressed by the first network device, and/or include uncompressed data packets (SDUs).
  • the data packet received by the terminal device from the first network device is the data packet from the core network device (for example, the UPF user plane function).
  • the data packets of the subsequent terminal device will be transmitted from the core network device to the second network device.
  • the terminal device performs cell handover for the data packets sent by the first network device but not successfully received by the terminal device, the first network device will start from the data packet with the smallest sequence number that has not received an ACK from the terminal device, and go to the first network device.
  • the second network device forwards the data packet, that is, the first network device forwards the data packet that has not received the ACK from the terminal device to the second network device.
  • the part of the data packets forwarded to the second network device may include data packets that have been compressed by the first network device, and/or include data packets that have not been compressed by the first network device.
  • S1210 does not need to be performed, so S1210 is an optional step.
  • the second network device sends N compressed data packets to the terminal device, and correspondingly, the terminal device receives N compressed data packets from the second network device.
  • the N compressed data packets are part or all of the M compressed data packets, for example, N is an integer less than or equal to M.
  • the second network device may send the N compressed data packets in an ascending sequence of the sequence numbers of the compressed data packets, starting from the first compressed data packet of the terminal device that is not determined to be successfully received.
  • the second network device continues to send data packets to the terminal device. Since the terminal device has not received successfully compressed data packets before the cell handover, the second network device sends N compressed data packets to the terminal device. Bag. For example, after updating the second cache, the second network device may compress N data packets according to the updated second cache to obtain N compressed data packets, and then send the N compressed data packets to the terminal device. Some or all of the N data packets are, for example, sent by the first network device to the second network device, or the N data packets may also be obtained by the second network device from the core network device. For more information about S1211, please refer to S1011 in the embodiment shown in FIG. 10.
  • status report the status report in this embodiment of the present application may indicate K compressed data packets
  • the status report may be sent by the terminal device to the first network device
  • the first network device may send the status report to the second network device
  • the status report may also be sent by the terminal device to the second network device.
  • the terminal device decompresses the N compressed data packets based on the third cache, or the terminal device decompresses the N compressed data packets and the K compressed data packets based on the third cache.
  • S1212 For more content of S1212, reference may be made to S1107 in the embodiment shown in FIG. 11 .
  • the terminal device and the first network device do not reset the cache, and if the second indication information received by the terminal device indicates that the terminal device does not continue to use the third cache, or the protocol stipulates that the terminal device does not continue to use the third cache, Then the terminal device can reset the third cache, and also reset the first cache for the first network device.
  • the processing methods of the terminal device and the first network device are introduced as follows.
  • the PDCP layer of the terminal device when the PDCP layer of the terminal device is rebuilt, it has received the compressed data packets 3, 4, 5, and 7, but has not yet received the compressed data packets 1, 2, and 6. After the PDCP layer receives the compressed data packets 3, 4, 5, and 7, the PDCP reconstruction instruction can trigger the decompression of these compressed data packets. If the PDCP layer fails to decompress the compressed data packets 3, 4, 5, and 7, then the PDCP layer fails to decompress the compressed data packets.
  • a PDCP re-establishment indication can trigger the PDCP layer to drop out-of-order compressed packets (there is a special case if the packet from the sender is an uncompressed packet , then these data packets do not need to be discarded even if they are out of order), that is, instead of decompressing the compressed data packets 3, 4, 5, and 7, the compressed data packets 3, 4, 5, and 7 are directly discarded, and the out-of-order ones are discarded directly.
  • the scheme of compressing data packets can reduce the number of decompression times, improve processing efficiency, save energy consumption, and avoid wasting resources for ineffective decompression processing.
  • the RLC layer of the terminal device after receiving the compressed data packet, the RLC layer of the terminal device will send ACK information to the first network device, and for the received compressed data packet, for example, the RLC layer of the terminal device will send ACK to the first network device.
  • the second network device may retransmit the compressed data packet to the terminal device. For example, the second network device starts from the first compressed data packet that has not received an ACK. Retransmission. For example, if the second network device receives ACKs for compressed data packets 0, 3, 4, 5, and 7, but does not receive ACKs for compressed data packets 1, 2, and 6, the second network device will retransmit compressed data packets 1-compressed Packet 7. The second network device will rebuild the PDCP layer and reset the second cache during the cell handover process, and the second network device will compress the data packets according to the reset second cache.
  • the compressed data packets 1 to 7 previously sent by the second network device to the terminal device are all obtained by compressing the data packets 1 to 7 according to the second cache before the reset, and at this time, the second network device will Data packets 1 to 7 are re-compressed according to the reset second cache to obtain compressed data packets 1 to 7, and the second network device sends these compressed data packets to the terminal device. It can be seen that, if the third cache is not used continuously, for the same data packet, the first network device needs to compress, and the second network device needs to compress again.
  • the number of times of compression of the network device can be reduced, and the processing efficiency of the network device can be improved. If the terminal device sends a status report to the network device, the amount of data sent by the network device can also be reduced, thereby saving transmission overhead.
  • FIG. 13 is a schematic structural diagram of a communication apparatus 1300 provided by an embodiment of the present application.
  • the communication apparatus 1300 may be the terminal device described in any one of the embodiment shown in FIG. 7 , the embodiment shown in FIG. 10 , the embodiment shown in FIG. 11 , or the embodiment shown in FIG. 12 , and is used for The method executed by the terminal device in the above method embodiment is implemented.
  • the communication apparatus 1300 may also be the first embodiment described in any of the embodiment shown in FIG. 7 , the embodiment shown in FIG. 10 , the embodiment shown in FIG. 11 , or the embodiment shown in FIG. 12 .
  • a network device configured to implement the method corresponding to the first network device in the foregoing method embodiments.
  • the communication apparatus 1300 may also be the second embodiment described in any of the embodiment shown in FIG. 7 , the embodiment shown in FIG. 10 , the embodiment shown in FIG. 11 , or the embodiment shown in FIG. 12 .
  • a network device configured to implement the method corresponding to the second network device in the above method embodiments. For specific functions, refer to the descriptions in the foregoing method embodiments.
  • Communication device 1300 includes one or more processors 1301 .
  • the processor 1301 may also be referred to as a processing unit, and may implement certain control functions.
  • the processor 1301 may be a general-purpose processor or a special-purpose processor or the like. For example, including: baseband processors, central processing units, application processors, modem processors, graphics processors, image signal processors, digital signal processors, video codec processors, controllers, memories, and/or Neural network processors, etc.
  • the baseband processor may be used to process communication protocols and communication data.
  • the central processing unit may be used to control the communication device 1300, execute software programs and/or process data.
  • the different processors can be stand-alone devices, or they can be integrated in one or more processors, for example, on one or more application specific integrated circuits.
  • the communication apparatus 1300 includes one or more memories 1302 for storing instructions 1304, and the instructions 1304 can be executed on the processor, so that the communication apparatus 1300 executes the methods described in the above method embodiments.
  • the memory 1302 may also store data.
  • the processor and the memory can be provided separately or integrated together.
  • the communication apparatus 1300 may include instructions 1303 (sometimes also referred to as codes or programs), and the instructions 1303 may be executed on the processor, so that the communication apparatus 1300 executes the methods described in the above embodiments .
  • Data may be stored in the processor 1301 .
  • the communication device 1300 may further include a transceiver 1305 and an antenna 1306 .
  • the transceiver 1305 may be referred to as a transceiver unit, a transceiver, a transceiver circuit, a transceiver, an input and output interface, etc., and is used to implement the transceiver function of the communication device 1300 through the antenna 1306.
  • the communication device 1300 may further include one or more of the following components: a wireless communication module, an audio module, an external memory interface, an internal memory, a universal serial bus (USB) interface, a power management module, an antenna, Speakers, microphones, I/O modules, sensor modules, motors, cameras, or displays, etc. It can be understood that, in some embodiments, the communication device 1300 may include more or less components, or some components may be integrated, or some components may be separated. These components may be implemented in hardware, software, or a combination of software and hardware.
  • the processor 1301 and the transceiver 1305 described in the embodiments of the present application may be implemented in an integrated circuit (IC), an analog IC, a radio frequency identification (RFID), a mixed-signal IC, and an application specific integrated circuit (application specific integrated circuit). integrated circuit, ASIC), printed circuit board (printed circuit board, PCB), or electronic equipment, etc.
  • IC integrated circuit
  • ASIC radio frequency identification
  • PCB printed circuit board
  • electronic equipment etc.
  • it may be an independent device (eg, an independent integrated circuit, a mobile phone, etc.), or may be a part of a larger device (eg, a module that can be embedded in other devices). The description of the terminal device and the network device will not be repeated here.
  • the embodiments of the present application provide a terminal device (for convenience of description, referred to as UE), which can be used in the foregoing embodiments.
  • the terminal device includes corresponding means, units and means for realizing the functions of the terminal device described in the embodiments shown in any one or more of FIG. 7 , FIG. 10 , FIG. 11 or FIG. 12 . / or circuit.
  • a terminal device includes a transceiver module, which is used to support the terminal device to implement a transceiver function, and a processing module, which is used to support the terminal device to process signals.
  • FIG. 14 is a schematic structural diagram of a terminal device provided by an embodiment of the present application.
  • the terminal device 1400 may be applicable to the architecture shown in FIG. 3 or FIG. 4 .
  • FIG. 14 only shows the main components of the terminal device 1400 .
  • the terminal device 1400 includes a processor, a memory, a control circuit, an antenna, and an input and output device.
  • the processor is mainly used to process communication protocols and communication data, and to control the entire terminal device 1400 , execute software programs, and process data of the software programs.
  • the memory is mainly used to store software programs and data.
  • the control circuit is mainly used for the conversion of the baseband signal and the radio frequency signal and the processing of the radio frequency signal.
  • Antennas are mainly used to send and receive radio frequency signals in the form of electromagnetic waves.
  • Input and output devices such as touch screens, display screens, microphones, keyboards, etc., are mainly used to receive data input by users and output data to users.
  • the processor can read the software program in the storage unit, interpret and execute the instructions of the software program, and process the data of the software program.
  • the processor performs baseband processing on the data to be sent, and outputs the baseband signal to the control circuit.
  • the control circuit performs radio frequency processing on the baseband signal and sends the radio frequency signal through the antenna in the form of electromagnetic waves.
  • the control circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor, which converts the baseband signal into data and processes the data .
  • FIG. 14 only shows one memory and one processor.
  • terminal device 1400 may include multiple processors and memories.
  • the memory may also be referred to as a storage medium or a storage device, etc., which is not limited in this embodiment of the present invention.
  • the processor may include a baseband processor and a central processing unit.
  • the baseband processor is mainly used to process communication protocols and communication data
  • the central processing unit is mainly used to control the entire terminal device 1400.
  • the software program is executed, and the data of the software program is processed.
  • the processor in FIG. 14 integrates the functions of the baseband processor and the central processing unit.
  • the baseband processor and the central processing unit may also be independent processors, which are interconnected through technologies such as a bus.
  • the terminal device 1400 may include multiple baseband processors to adapt to different network standards, the terminal device 1400 may include multiple central processors to enhance its processing capability, and various components of the terminal device 1400 may be connected through various buses.
  • the baseband processor may also be expressed as a baseband processing circuit or a baseband processing chip.
  • the central processing unit can also be expressed as a central processing circuit or a central processing chip.
  • the function of processing the communication protocol and communication data may be built in the processor, or may be stored in the storage unit in the form of a software program, and the processor executes the software program to realize the baseband processing function.
  • the antenna and control circuit with a transceiving function can be regarded as the transceiving unit 1410 of the terminal device 1400
  • the processor having a processing function can be regarded as the processing unit 1420 of the terminal device 1400
  • the terminal device 1400 includes a transceiver unit 1410 and a processing unit 1420 .
  • the transceiving unit may also be referred to as a transceiver, a transceiver, a transceiving device, or the like.
  • the device for implementing the receiving function in the transceiver unit 1410 may be regarded as a receiving unit, and the device for implementing the transmitting function in the transceiver unit 1410 may be regarded as a transmitting unit, that is, the transceiver unit 1410 includes a receiving unit and a transmitting unit.
  • the receiving unit may also be referred to as a receiver, a receiver, a receiving circuit, and the like
  • the transmitting unit may be referred to as a transmitter, a transmitter, or a transmitting circuit, or the like.
  • the embodiment of the present application also provides a network device, and the network device can be used in each of the foregoing embodiments.
  • the network device includes means for implementing the functions of the first network device described in any one or more of the embodiments shown in FIG. 7 , FIG. 10 , FIG. 11 or FIG. 12 , units and/or circuits.
  • the network device includes means for implementing the functions of the second network device described in any one or more of the embodiments shown in FIG. 7 , FIG. 10 , FIG. 11 or FIG. 12 . ), units and/or circuits.
  • the network device includes a transceiver module to support the network device to implement a transceiver function, and a processing module to support the network device to process signals.
  • FIG. 15 is a schematic structural diagram of a network device provided by an embodiment of the present application.
  • the network device can be adapted to the architecture shown in FIG. 3 or FIG. 4 .
  • the network equipment includes: a baseband device 1501 , a radio frequency device 1502 , and an antenna 1503 .
  • the radio frequency device 1502 receives the information sent by the terminal device through the antenna 1503, and sends the information sent by the terminal device to the baseband device 1501 for processing.
  • the baseband apparatus 1501 processes the information of the terminal equipment and sends it to the radio frequency apparatus 1502, and the radio frequency apparatus 1502 processes the information of the terminal equipment and sends it to the terminal equipment through the antenna 1503.
  • the baseband device 1501 includes one or more processing units 15011 , storage units 15012 and interfaces 15013 .
  • the processing unit 15011 is configured to support the network device to perform the functions of the network device in the foregoing method embodiments.
  • the storage unit 15012 is used to store software programs and/or data.
  • the interface 15013 is used for exchanging information with the radio frequency device 1502, and the interface includes an interface circuit for inputting and outputting information.
  • the processing unit is an integrated circuit, such as one or more ASICs, or, one or more DSPs, or, one or more FPGAs, or a combination of these types of integrated circuits. These integrated circuits can be integrated together to form chips.
  • the storage unit 15012 and the processing unit 15011 may be located in the same chip, that is, an on-chip storage element. Alternatively, the storage unit 15012 and the processing unit 15011 may be located on a different chip, that is, an off-chip storage element.
  • the storage unit 15012 may be a memory, or may be a collective term for multiple memories or storage elements.
  • the network device may implement some or all of the steps in the foregoing method embodiments in the form of one or more processing unit schedulers.
  • the corresponding functions of the first network device and/or the second network device in the embodiments shown in any one or more of FIG. 7 , FIG. 10 , FIG. 11 or FIG. 12 are implemented.
  • the one or more processing units may support wireless access technologies of the same standard, or may support wireless access standards of different standards.
  • the disclosed system, apparatus and method may be implemented in other manners.
  • the apparatus embodiments described above are only illustrative.
  • the division of the units is only a logical function division.
  • the units described as separate components may or may not be physically separated.
  • the components shown may or may not be physical units, ie may be located in one place, or may be distributed over multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
  • the functions, if implemented in the form of software functional units and sold or used as independent products, may be stored in a computer-readable storage medium.
  • the technical solution of the present application can be embodied in the form of a software product in essence, or the part that contributes to the prior art or the part of the technical solution.
  • the computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned computer-readable storage medium can be any available medium that can be accessed by a computer.
  • the computer-readable medium may include random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), Erasable programmable read only memory (erasable PROM, EPROM), electrically erasable programmable read only memory (electrically erasable programmable read only memory, EEPROM), compact disc read-only memory (compact disc read-only memory, CD- ROM), universal serial bus flash disk, removable hard disk, or other optical disk storage, magnetic disk storage medium, or other magnetic storage device, or capable of carrying or storing desired data in the form of instructions or data structures program code and any other medium that can be accessed by a computer.
  • RAM random access memory
  • ROM read-only memory
  • PROM programmable read-only memory
  • EPROM Erasable programmable read only memory
  • EEPROM electrically erasable programmable read only memory
  • compact disc read-only memory compact disc read-only memory
  • CD- ROM compact disc read-only memory
  • universal serial bus flash disk removable hard disk,
  • RAM static random access memory
  • DRAM dynamic random access memory
  • SDRAM synchronous dynamic random access memory
  • double data rate SDRAM double data rate SDRAM
  • DDR SDRAM double data rate SDRAM
  • ESDRAM enhanced synchronous dynamic random access memory
  • SLDRAM synchronous link dynamic random access memory
  • direct rambus RAM direct rambus RAM

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Abstract

本申请涉及一种通信方法及装置。终端设备发送M个压缩数据包，M个压缩数据包是基于第一缓存对M个数据包压缩得到的。终端设备重建PDCP层，且不重置第一缓存。终端设备再发送N个压缩数据包，N个压缩数据包是M个压缩数据包中的部分或全部。终端设备在重建PDCP层的情况下，不重置第一缓存，那么如果终端设备需要重传数据包，则终端设备可将之前得到的压缩数据包进行重传即可，无需再次对数据包进行压缩，这样就减少了数据包的压缩次数，减少了终端设备的处理时间，提高了处理效率。而且由于减少了终端设备的工作量，也就减小了终端设备的功耗。

Description

一种通信方法及装置
相关申请的交叉引用
本申请要求在2021年01月22日提交中国国家知识产权局、申请号为202110086421.0、申请名称为“一种数据传输方法、终端及网络设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中；本申请要求在2021年03月02日提交中国国家知识产权局、申请号为202110230452.9、申请名称为“一种通信方法及装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及一种通信方法及装置。
背景技术
在长期演进(long term evolution，LTE)系统的确认模式(acknowledged mode，AM)传输中，引入了上行数据压缩(uplink data compression，UDC)技术，在分组数据汇聚协议(packet data convergence protocol，PDCP)层进行实现。UDC技术主要针对某些有大量重复内容的数据包，如LTE网络语音业务(voice over long term evolution，VoLTE)中传输会话发起协议(session initiation protocol，SIP)的数据包，通过传输数据包与数据包之间的差异部分，来降低传输的数据量。
当终端设备发生小区切换时，终端设备会重建PDCP层，UDC技术对应的缓存(buffer)也会重置(reset)，该缓存用于压缩数据包。而在小区切换前，基站可能未正确接收来自终端设备的数据包，例如终端设备发送了多个数据包，而其中有一部分数据包可能基站并未收到，因此终端设备需要重传。由于用于压缩数据包的缓存发生了重置，因此终端设备在重传数据包时，需要重新根据重置后的缓存再对数据包进行压缩，也就是说，对于同一个数据包，终端设备可能需要压缩两次，这无疑是增加了终端设备的处理时间，降低了处理效率。
发明内容
本申请实施例提供一种通信方法及装置，用于减少终端设备的压缩次数，以相应提高终端设备的处理效率。
第一方面，提供第一种通信方法，该方法可由终端设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现终端设备的功能。该方法包括：发送M个压缩数据包，所述M个压缩数据包是基于第一缓存对M个数据包压缩得到的，M为正整数；重建PDCP层，且不重置所述第一缓存；发送N个压缩数据包，所述N个压缩数据包是所述M个压缩数据包中的部分或全部，N为小于或等于M的正整数。
在本申请实施例中，终端设备在重建PDCP层的情况下，不重置第一缓存，那么如果终端设备需要重传数据包，则终端设备可将之前得到的压缩数据包进行重传即可，无需再次对数据包进行压缩，这样就减少了数据包的压缩次数，减少了终端设备的处理时间，提 高了处理效率。而且由于减少了终端设备的工作量，也就减小了终端设备的功耗。
结合第一方面，在第一方面的第一种可选的实施方式中，所述方法还包括：接收状态报告，所述状态报告用于指示网络设备(第一网络设备或第二网络设备)已接收的压缩数据包。例如该状态报告指示K个压缩数据包，终端设备接收该状态报告后，就可以获知网络设备接收了K个压缩数据包。例如，该状态报告可通过比特地图(bitmap)实现，该bitmap包括的比特数可以为M，M个比特与M个压缩数据包一一对应。如果网络设备接收了一个压缩数据包，则该压缩数据包对应的比特就置为“1”，如果网络设备未接收一个压缩数据包，则该压缩数据包对应的比特就置为“0”，这样可以使得终端设备很快明确网络设备接收了哪些压缩数据包。又例如，该状态报告可包括网络设备已接收的压缩数据包的序号，和/或，包括网络设备未接收的压缩数据包的序号，这样都能使得终端设备明确网络设备接收了哪些压缩数据包。
结合第一方面的第一种可选的实施方式，在第一方面的第二种可选的实施方式中，所述N个压缩数据包中不包括所述网络设备(第一网络设备或第二网络设备)已接收的压缩数据包。如果网络设备向终端设备发送了状态报告，该状态报告指示了网络设备已接收的压缩数据包，那么对于网络设备已接收的压缩数据包，终端设备可以不再发送，而只需发送网络设备未接收的压缩数据包。这样可以减少终端设备重发的数据量，节省传输开销。
结合第一方面或第一方面的第一种可选的实施方式或第一方面的第二种可选的实施方式，在第一方面的第三种可选的实施方式中，所述N个压缩数据包中序号最小的数据包是网络设备未成功接收的数据包中序号最小的数据包。终端设备在进行小区切换完毕后，或者终端设备在PDCP层重建完毕后，可以向网络设备(第一网络设备或第二网络设备)重发N个压缩数据包。终端设备可从网络设备的第一个未确定成功接收的压缩数据包开始，按照压缩数据包的序号升序的顺序发送N个压缩数据包。例如N个压缩数据包中的第一个压缩数据包(或者说，N个压缩数据包中序号最小的压缩数据包)，可以是第一网络设备第一个未成功接收的压缩数据包(或者说，是第一网络设备未成功接收的数据包中序号最小的压缩数据包)，这样可以减少第一网络设备丢包的概率。
结合第一方面或第一方面的第一种可选的实施方式至第一方面的第三种可选的实施方式中的任一种可选的实施方式，在第一方面的第四种可选的实施方式中，所述方法还包括：发送能力信息，所述能力信息用于指示支持继续使用所述第一缓存。网络设备(第一网络设备或第二网络设备)根据该能力信息就能明确终端设备是否支持继续使用第一缓存。如果终端设备支持继续使用第一缓存，网络设备就可以指示终端设备继续使用第一缓存，如果终端设备不支持继续使用第一缓存，网络设备可不指示终端设备继续使用第一缓存或指示终端设备重置第一缓存。或者，终端设备也可以不发送能力信息，网络设备可以根据其他因素确定是否指示终端设备继续使用第一缓存，或者终端设备是否继续使用第一缓存也可以通过协议规定等。
结合第一方面或第一方面的第一种可选的实施方式至第一方面的第四种可选的实施方式中的任一种可选的实施方式，在第一方面的第五种可选的实施方式中，所述方法还包括：接收切换命令，所述切换命令用于指示小区切换或重建PDCP层，还用于指示继续使用所述第一缓存。例如，该切换命令包括第一指示信息，第一指示信息可指示重建PDCP层，或者指示小区切换。可选的，该切换命令还可包括第二指示信息，第二指示信息可指示继续使用第一缓存，或者，第二指示信息可指示在重建PDCP时不重置第一缓存。或者， 第二指示信息也可以不包括在该切换命令中，第一网络设备可以通过其他的消息向终端设备发送第二指示信息。或者，例如协议规定继续使用第一缓存，或者协议规定在重建PDCP时不重置第一缓存，则第一网络设备也可以不发送第二指示信息。
结合第一方面或第一方面的第一种可选的实施方式至第一方面的第五种可选的实施方式中的任一种可选的实施方式，在第一方面的第六种可选的实施方式中，所述第一缓存对应于第一无线承载，所述第一无线承载包括所述终端设备的部分或全部无线承载。例如对于该终端设备被配置了使用本申请实施例所提供的压缩技术的无线承载来说，可以是一个无线承载对应一个缓存，无线承载与缓存为一一对应关系；或者，也可能多个无线承载对应一个缓存，例如该缓存中可以为不同的无线承载分别分配空间，这样可节省缓存的数量。
结合第一方面或第一方面的第一种可选的实施方式至第一方面的第六种可选的实施方式中的任一种可选的实施方式，在第一方面的第七种可选的实施方式中，发送M个压缩数据包，包括：向第一网络设备发送所述M个压缩数据包；发送N个压缩数据包，包括：向所述第一网络设备发送所述N个压缩数据包。如果终端设备的小区切换过程为共站切换过程，即，终端设备在进行小区切换前接入的是第一网络设备，在进行小区切换后接入的也是第一网络设备，那么终端设备无论是发送M个压缩数据包还是发送N个压缩数据包，都是发送给第一网络设备。
结合第一方面或第一方面的第一种可选的实施方式至第一方面的第六种可选的实施方式中的任一种可选的实施方式，在第一方面的第八种可选的实施方式中，发送M个压缩数据包，包括：向第一网络设备发送所述M个压缩数据包，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；发送N个压缩数据包，包括：向第二网络设备发送所述N个压缩数据包，所述第一网络设备是所述终端设备进行小区切换后接入的网络设备。如果终端设备的小区切换过程为跨站切换过程，即，终端设备在进行小区切换前接入的是第一网络设备，在进行小区切换后接入的是第二网络设备，而终端设备发送M个压缩数据包可能发生在小区切换前，而发送N个压缩数据包可能发生在小区切换后，因此终端设备可向第一网络设备发送M个压缩数据包，而向第二网络设备发送N个压缩数据包。
第二方面，提供第二种通信方法，该方法可由第一网络设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现第一网络设备的功能。示例性地，所述第一网络设备为接入网设备，例如基站。该方法包括：从终端设备接收K个压缩数据包，所述K个压缩数据包是基于第一缓存对K个数据包压缩得到的，K为正整数；重建PDCP层，且不重置第二缓存，所述第二缓存用于所述第一网络设备对基于所述第一缓存压缩的数据包进行解压缩。
终端设备在重建PDCP层的情况下，不重置第一缓存，那么相应的第一网络设备也不重置与第一缓存对应的第二缓存。如果终端设备需要重传数据包，则终端设备可将之前得到的压缩数据包进行重传即可，无需再次对数据包进行压缩，这样就减少了数据包的压缩次数，减少了终端设备的处理时间，提高了处理效率。而且由于减少了终端设备的工作量，也就减小了终端设备的功耗。而第一网络设备未重置第二缓存，则第一缓存与第二缓存的状态可以保持一致，因此第一网络设备能够对来自终端设备的压缩数据包进行解压缩，减小了第一网络设备的丢包率。
结合第二方面，在第二方面的第一种可选的实施方式中，所述K个数据包的序号与所 述第一网络设备已解压缩数据包的序号不连续。例如，K个压缩数据包的序号与第一网络设备已成功解压缩并已递交给上层的最后一个数据包之间的序号不连续，表明第一网络设备有未接收的压缩数据包，而未接收的压缩数据包会影响第一网络设备对K个压缩数据包的解压缩。
结合第二方面或第二方面的第一种可选的实施方式，在第二方面的第二种可选的实施方式中，所述方法还包括：向第二网络设备发送所述K个压缩数据包，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备。例如终端设备的小区切换过程为跨站切换过程，即，终端设备在进行小区切换前接入的是第一网络设备，而在小区切换后接入的是第二网络设备。那么，由于终端设备进行了小区切换，则第一网络设备不必对K个压缩数据包进行解压缩，而是可将K个压缩数据包通过网络设备间接口(如Xn口)转发或发送给第二网络设备，由第二网络设备对K个压缩数据包进行处理。
结合第二方面或第二方面的第一种可选的实施方式或第二方面的第二种可选的实施方式，在第二方面的第三种可选的实施方式中，所述方法还包括：向第二网络设备发送指示信息，所述指示信息用于指示所述第二缓存的内容，所述第二缓存的内容用于更新第三缓存，所述第三缓存用于所述第二网络设备对基于所述第一缓存压缩的数据包进行解压缩，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备。例如终端设备的小区切换过程为跨站切换过程，即，终端设备在进行小区切换前接入的是第一网络设备，而在小区切换后接入的是第二网络设备。那么第一网络设备可向第二网络设备指示第二缓存的内容，第二网络设备可根据第二缓存的内容更新第二网络设备维护的第三缓存，使得第三缓存与第一缓存的状态保持一致，从而使得第二网络设备能对来自终端设备的压缩数据包进行正确的解压缩。
结合第二方面或第二方面的第一种可选的实施方式至第二方面的第三种可选的实施方式中的任一种可选的实施方式，在第二方面的第四种可选的实施方式中，所述方法还包括：向所述第二网络设备发送第一消息，所述第一消息用于询问是否支持所述终端设备继续使用第一缓存，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；所述第一网络设备从所述第二网络设备接收第二消息，所述第二消息用于指示支持所述终端设备继续使用所述第一缓存。例如终端设备的小区切换过程为跨站切换过程，即，终端设备在进行小区切换前接入的是第一网络设备，而在小区切换后接入的是第二网络设备，那么第一网络设备可询问第二网络设备是否支持终端设备继续使用第一缓存。例如，如果第二网络设备不支持终端设备继续使用第一缓存，那么第一网络设备可配置终端设备重置第一缓存，以使得终端设备的行为与第二网络设备支持的行为一致。
结合第二方面或第二方面的第一种可选的实施方式，在第二方面的第五种可选的实施方式中，所述方法还包括：向所述终端设备发送状态报告，所述状态报告用于指示所述第一网络设备已接收所述K个压缩数据包。
结合第二方面的第五种可选的实施方式，在第二方面的第六种可选的实施方式中，所述方法还包括：从所述终端设备接收N个压缩数据包，所述N个压缩数据包是M个压缩数据包的中的部分或全部，所述K个压缩数据包是所述M个压缩数据包的中的部分或全部，所述M个数据包的序号连续，且所述M个压缩数据包是基于所述第一缓存对M个数 据包压缩得到的，M为正整数，N为小于或等于M的正整数，且K为小于或等于M的正整数。
结合第二方面的第六种可选的实施方式，在第二方面的第七种可选的实施方式中，所述N个压缩数据包中不包括所述K个压缩数据包。
结合第二方面的第五种可选的实施方式或第二方面的第六种可选的实施方式或第二方面的第七种可选的实施方式，在第二方面的第八种可选的实施方式中，所述N个压缩数据包中序号最小的数据包是所述第一网络设备未成功接收的数据包中序号最小的数据包。
结合第二方面或第二方面的第一种可选的实施方式至第二方面的第八种可选的实施方式中的任一种可选的实施方式，在第二方面的第九种可选的实施方式中，所述方法还包括：从所述终端设备接收能力信息，所述能力信息用于指示所述终端设备支持继续使用所述第一缓存。
结合第二方面或第二方面的第一种可选的实施方式至第二方面的第九种可选的实施方式中的任一种可选的实施方式，在第二方面的第十种可选的实施方式中，所述方法还包括：向所述终端设备发送切换命令，所述切换命令用于指示小区切换或重建PDCP层，还用于指示继续使用所述第一缓存。
结合第二方面或第二方面的第一种可选的实施方式至第二方面的第十种可选的实施方式中的任一种可选的实施方式，在第二方面的第十一种可选的实施方式中，所述第一缓存对应于第一无线承载，所述第一无线承载包括所述终端设备的部分或全部无线承载。
关于第二方面或部分可选的实施方式所带来的技术效果，可参考对于第一方面或相应实施方式的技术效果的介绍。
第三方面，提供第三种通信方法，该方法可由第二网络设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现第二网络设备的功能。示例性地，所述第二网络设备为接入网设备，例如基站。该方法包括：从第一网络设备接收K个压缩数据包，所述K个压缩数据包是基于第一缓存对K个数据包压缩得到的，所述第二网络设备是终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；从所述第一网络设备接收指示信息，所述指示信息用于指示第二缓存的内容，所述第二缓存用于所述第一网络设备对基于所述第一缓存压缩的数据包进行解压缩；根据所述第二缓存的内容更新第三缓存，所述第三缓存用于所述第二网络设备对基于所述第一缓存压缩的数据包进行解压缩。
结合第三方面，在第三方面的第一种可选的实施方式中，所述K个数据包的序号与所述第二网络设备已接收的数据包的序号不连续。
结合第三方面或第三方面的第一种可选的实施方式，在第三方面的第二种可选的实施方式中，所述方法还包括：从所述终端设备接收N个压缩数据包，所述N个压缩数据包是M个压缩数据包的中的部分或全部，所述K个压缩数据包是所述M个压缩数据包的中的部分或全部，所述M个数据包的序号连续，且所述M个压缩数据包是基于所述第一缓存对M个数据包压缩得到的，M为正整数，N为小于或等于M的正整数，且K为小于或等于M的正整数。
结合第三方面或第三方面的第一种可选的实施方式或第三方面的第二种可选的实施方式，在第三方面的第三种可选的实施方式中，所述方法还包括：从所述第一网络设备接收第一消息，所述第一消息用于询问是否支持所述终端设备继续使用第一缓存；向所述第 一网络设备发送第二消息，所述第二消息用于指示支持所述终端设备继续使用所述第一缓存。
结合第三方面或第三方面的第一种可选的实施方式至第三方面的第三种可选的实施方式中的任一种可选的实施方式，在第三方面的第四种可选的实施方式中，所述方法还包括：向所述终端设备发送状态报告，所述状态报告用于指示所述第二网络设备已接收所述K个压缩数据包。
结合第三方面的第四种可选的实施方式，在第三方面的第五种可选的实施方式中，所述N个压缩数据包中不包括所述K个压缩数据包。
结合第三方面或第三方面的第一种可选的实施方式至第三方面的第五种可选的实施方式中的任一种可选的实施方式，在第三方面的第六种可选的实施方式中，所述N个压缩数据包中序号最小的数据包是所述第二网络设备未成功接收的数据包中序号最小的数据包。
结合第三方面或第三方面的第一种可选的实施方式至第三方面的第六种可选的实施方式中的任一种可选的实施方式，在第三方面的第七种可选的实施方式中，所述第一缓存对应于第一无线承载，所述第一无线承载包括所述终端设备的部分或全部无线承载。
关于第三方面或各种可选的实施方式所带来的技术效果，可参考对于第一方面或相应实施方式的技术效果的介绍，和/或，参考对于第二方面或相应实施方式的技术效果的介绍。
其中，第一方面、第二方面或第三方面中的任意一个或多个方面所述的方法所涉及的是上行压缩过程。
第四方面，提供第四种通信方法，该方法可由第一网络设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现第一网络设备的功能。示例性地，所述第一网络设备为接入网设备，例如基站。该方法包括：向终端设备发送M个压缩数据包，所述M个压缩数据包是基于第一缓存对M个数据包压缩得到的，M为正整数；重建PDCP层，且不重置所述第一缓存。
在本申请实施例中，第一网络设备在重建PDCP层的情况下，不重置第一缓存，那么如果第一网络设备需要重传数据包，则第一网络设备可将之前得到的压缩数据包进行重传即可，无需再次对数据包进行压缩，这样就减少了数据包的压缩次数，减少了第一网络设备的处理时间，提高了处理效率。而且由于减少了第一网络设备的工作量，也就减小了第一网络设备的功耗。
结合第四方面，在第四方面的第一种可选的实施方式中，所述方法还包括：向第二网络设备发送指示信息，所述指示信息用于指示所述第一缓存的内容，所述第一缓存的内容用于更新第二缓存，所述第二缓存用于所述第二网络设备对数据包进行压缩，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备。
结合第四方面或第四方面的第一种可选的实施方式，在第四方面的第二种可选的实施方式中，所述方法还包括：向第二网络设备发送第一消息，所述第一消息用于询问是否支持所述终端设备继续使用第三缓存，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备；从所述第二网络设备接收第二消息，所述第二消息用于指示支持所述终端设备继续使用所述第三缓存。
结合第四方面，在第四方面的第三种可选的实施方式中，所述方法还包括：从所述终端设备接收状态报告，所述状态报告用于指示所述终端设备已接收的压缩数据包。
结合第四方面的第三种可选的实施方式，在第四方面的第四种可选的实施方式中，所述方法还包括：向所述终端设备发送N个压缩数据包，所述N个压缩数据包是所述M个压缩数据包中的部分或全部，N为小于或等于M的正整数。
结合第四方面的第四种可选的实施方式，在第四方面的第五种可选的实施方式中，所述N个压缩数据包不包括所述终端设备已接收的压缩数据包。
结合第四方面的第三种可选的实施方式或第四方面的第四种可选的实施方式或第四方面的第五种可选的实施方式，在第四方面的第六种可选的实施方式中，所述N个压缩数据包中序号最小的数据包是所述终端设备未成功接收的数据包中序号最小的数据包。
结合第四方面或第四方面的第一种可选的实施方式至第四方面的第六种可选的实施方式中的任一种可选的实施方式，在第四方面的第七种可选的实施方式中，所述方法还包括：从所述终端设备接收能力信息，所述能力信息用于指示所述终端设备支持继续使用第三缓存，所述第三缓存用于所述终端设备对基于所述第一缓存或第二缓存压缩的数据包进行解压缩，所述第二缓存用于第二网络设备对数据包进行压缩，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备。
结合第四方面或第四方面的第一种可选的实施方式至第四方面的第七种可选的实施方式中的任一种可选的实施方式，在第四方面的第八种可选的实施方式中，所述方法还包括：向所述终端设备发送切换命令，所述切换命令用于指示小区切换或重建PDCP层，还用于指示所述终端设备继续使用第三缓存，所述第三缓存用于所述终端设备对基于所述第一缓存或第二缓存压缩的数据包进行解压缩，所述第二缓存用于第二网络设备对数据包进行压缩，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备。
关于第四方面或各种可选的实施方式所带来的技术效果，可参考对于第一方面或相应实施方式的技术效果的介绍，和/或，参考对于第二方面或相应实施方式的技术效果的介绍，和/或，参考对于第三方面或相应实施方式的技术效果的介绍。
第五方面，提供第五种通信方法，该方法可由第二网络设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现第二网络设备的功能。示例性地，所述第二网络设备为接入网设备，例如基站。该方法包括：从第一网络设备接收指示信息，所述指示信息用于指示第一缓存的内容，所述第一缓存用于所述第一网络设备对数据包进行压缩，所述第二网络设备是终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；根据所述第一缓存的内容更新第二缓存，所述第二缓存用于所述第二网络设备对数据包进行压缩。
结合第五方面，在第五方面的第一种可选的实施方式中，所述方法还包括：接收来自第一网络设备的第一消息，所述第一消息用于询问是否支持所述终端设备继续使用所述第三缓存；向第一网络设备发送第二消息，所述第二消息用于指示支持所述终端设备继续使用所述第三缓存。
结合第五方面或第五方面的第一种可选的实施方式，在第五方面的第二种可选的实施方式中，所述方法还包括：从所述终端设备接收状态报告，所述状态报告用于指示所述终端设备已接收的压缩数据包。
结合第五方面的第二种可选的实施方式，在第五方面的第三种可选的实施方式中，所 述方法还包括：根据更新的所述第二缓存对数据包进行压缩，得到N个压缩数据包；向所述终端设备发送所述N个压缩数据包。
结合第五方面的第三种可选的实施方式，在第五方面的第四种可选的实施方式中，所述N个压缩数据包不包括所述终端设备已接收的压缩数据包。
结合第五方面的第三种可选的实施方式或第五方面的第四种可选的实施方式，在第五方面的第五种可选的实施方式中，所述N个压缩数据包中序号最小的数据包是所述终端设备未成功接收的数据包中序号最小的数据包。
关于第五方面或各种可选的实施方式所带来的技术效果，可参考对于第一方面或相应实施方式的技术效果的介绍，和/或，参考对于第二方面或相应实施方式的技术效果的介绍，和/或，参考对于第三方面或相应实施方式的技术效果的介绍。
第六方面，提供第六种通信方法，该方法可由终端设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现终端设备的功能。该方法包括：接收K个压缩数据包，所述K个压缩数据包是基于第一缓存对K个数据包压缩得到的；重建PDCP层，且不重置第三缓存；接收N个压缩数据包，所述N个压缩数据包是基于第二缓存对N个数据包压缩的，K和N均为正整数；基于所述第三缓存对所述K个压缩数据包和所述N个压缩数据包解压缩，或，基于所述第三缓存对所述N个压缩数据包解压缩。
结合第六方面，在第六方面的第一种可选的实施方式中，接收K个压缩数据包，包括：从第一网络设备接收所述K个压缩数据包；接收N个压缩数据包，包括：从所述第一网络设备接收所述N个压缩数据包。
结合第六方面的第一种可选的实施方式，在第六方面的第二种可选的实施方式中，所述第一缓存和所述第二缓存是同一缓存，且所述第一缓存由所述第一网络设备维护。
结合第六方面，在第六方面的第三种可选的实施方式中，接收K个压缩数据包，包括：从第一网络设备接收所述K个压缩数据包；接收N个压缩数据包，包括：从第二网络设备接收所述N个压缩数据包，所述第二网络设备是终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备。
结合第六方面的第三种可选的实施方式，在第六方面的第四种可选的实施方式中，所述第一缓存由所述第一网络设备维护，所述第二缓存由所述第二网络设备维护。
结合第六方面或第六方面的第一种可选的实施方式至第六方面的第四种可选的实施方式，在第六方面的第五种可选的实施方式中，所述K个数据包的序号与所述终端设备已解压缩数据包的序号不连续。
结合第六方面或第六方面的第一种可选的实施方式至第六方面的第五种可选的实施方式，在第六方面的第六种可选的实施方式中，所述N个压缩数据包中序号最小的数据包是所述终端设备未成功接收的数据包中序号最小的数据包。
结合第六方面或第六方面的第一种可选的实施方式至第六方面的第六种可选的实施方式，在第六方面的第七种可选的实施方式中，所述方法还包括：发送状态报告，所述状态报告用于指示所述终端设备已接收所述K个压缩数据包。
结合第六方面的第七种可选的实施方式，在第六方面的第八种可选的实施方式中，所述N个压缩数据包中不包括所述K个压缩数据包。
结合第六方面或第六方面的第一种可选的实施方式至第六方面的第八种可选的实施方式，在第六方面的第九种可选的实施方式中，所述方法还包括：接收切换命令，所述切 换命令用于指示小区切换或重建PDCP层，还用于指示所述终端设备继续使用所述第三缓存。
结合第六方面或第六方面的第一种可选的实施方式至第六方面的第九种可选的实施方式，在第六方面的第十种可选的实施方式中，所述方法还包括：发送能力信息，所述能力信息用于指示所述终端设备支持继续使用所述第三缓存。
关于第六方面或各种可选的实施方式所带来的技术效果，可参考对于第一方面或相应实施方式的技术效果的介绍，和/或，参考对于第二方面或相应实施方式的技术效果的介绍，和/或，参考对于第三方面或相应实施方式的技术效果的介绍。
其中，第四方面、第五方面或第六方面中的任意一个或多个方面所述的方法所涉及的是下行压缩过程。
第七方面，提供第七种通信方法，该方法可由终端设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现终端设备的功能。该方法包括：接收切换命令，所述切换命令包括第一指示信息和第二指示信息，所述第一指示信息用于指示重建PDCP层或小区切换，所述第二指示信息用于指示所述终端设备继续使用第一缓存，所述第一缓存用于所述终端设备对数据包进行压缩；重建PDCP层，且不重置所述第一缓存。
结合第七方面，在第七种方面的第一种可选的实施方式中，所述方法还包括：接收状态报告，所述状态报告用于指示网络设备已接收的压缩数据包。
结合第七方面的第一种可选的实施方式，在第七种方面的第二种可选的实施方式中，所述方法还包括：从第一个未确定成功接收的压缩数据包开始，按照压缩数据包的序号升序的顺序发送N个压缩数据包，N为正整数。
结合第七方面的第二种可选的实施方式，在第七种方面的第三种可选的实施方式中，从第一个未确定成功接收的压缩数据包开始，按照压缩数据包的序号升序的顺序发送N个压缩数据包，包括：对所述N个压缩数据包进行完整性保护以及加密处理；发送处理后的N个压缩数据包。
结合第七方面或第七方面的第一种可选的实施方式至第七方面的第三种可选的实施方式中的任一种可选的实施方式，在第七种方面的第四种可选的实施方式中，所述方法还包括：发送能力信息，所述能力信息用于指示支持继续使用所述第一缓存。
结合第七方面或第七方面的第一种可选的实施方式至第七方面的第四种可选的实施方式中的任一种可选的实施方式，在第七种方面的第五种可选的实施方式中，所述第一缓存对应于第一无线承载，所述第一无线承载包括所述终端设备的部分或全部无线承载。
关于第七方面或各种可选的实施方式所带来的技术效果，可参考对于第一方面或相应实施方式的技术效果的介绍，和/或，参考对于第二方面或相应实施方式的技术效果的介绍，和/或，参考对于第三方面或相应实施方式的技术效果的介绍。
第八方面，提供第八种通信方法，该方法可由第一网络设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现第一网络设备的功能。示例性地，所述第一网络设备为接入网设备，例如基站。该方法包括：向终端设备发送切换命令，所述切换命令包括第一指示信息和第二指示信息，所述第一指示信息用于指示重建PDCP层或小区切换，所述第二指示信息用于指示继续使用第一缓存，所述第一缓存用于所述终端设备对数据包进行压缩；重建PDCP层，且不重置第二缓存，所述第二缓存用于所述第一网络设备对基于所述第一缓存压缩的数据包进行解压缩。
结合第八方面，在第八方面的第一种可选的实施方式中，所述方法还包括：向第二网络设备发送K个压缩数据包，所述K个压缩数据包来自所述终端设备，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备。
结合第八方面或第八方面的第一种可选的实施方式，在第八方面的第二种可选的实施方式中，所述方法还包括：向第二网络设备发送指示信息，所述指示信息用于指示所述第二缓存的内容，所述第二缓存的内容用于更新第三缓存，所述第三缓存用于所述第二网络设备对基于所述第一缓存压缩的数据包进行解压缩，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备。
结合第八方面或第八方面的第一种可选的实施方式或第八方面的第二种可选的实施方式，在第八方面的第三种可选的实施方式中，所述方法还包括：向所述第二网络设备发送第一消息，所述第一消息用于询问是否支持所述终端设备继续使用所述第一缓存，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；所述第一网络设备从所述第二网络设备接收第二消息，所述第二消息用于指示支持所述终端设备继续使用所述第一缓存。
结合第八方面，在第八方面的第四种可选的实施方式中，所述方法还包括：向所述终端设备发送状态报告，所述状态报告用于指示所述第一网络设备已接收的压缩数据包。
结合第八方面的第四种可选的实施方式，在第八方面的第五种可选的实施方式中，所述方法还包括：从所述终端设备接收N个压缩数据包，所述N个压缩数据包中序号最小的数据包是所述第一网络设备未成功接收的数据包中序号最小的数据包。
结合第八方面的第五种可选的实施方式，在第八方面的第六种可选的实施方式中，所述N个压缩数据包中不包括所述第一网络设备已接收的压缩数据包。
结合第八方面或第八方面的第一种可选的实施方式或第八方面的第六种可选的实施方式，在第八方面的第七种可选的实施方式中，所述方法还包括：从所述终端设备接收能力信息，所述能力信息用于指示所述终端设备支持继续使用所述第一缓存。
结合第八方面或第八方面的第一种可选的实施方式或第七方面的第六种可选的实施方式，在第八方面的第八种可选的实施方式中，所述第一缓存对应于第一无线承载，所述第一无线承载包括所述终端设备的部分或全部无线承载。
关于第八方面或各种可选的实施方式所带来的技术效果，可参考对于第一方面或相应实施方式的技术效果的介绍，和/或，参考对于第二方面或相应实施方式的技术效果的介绍，和/或，参考对于第三方面或相应实施方式的技术效果的介绍。
其中，第七方面和/或第八方面所述的方法所涉及的是上行压缩过程。
第九方面，提供第九种通信方法，该方法可由第一网络设备执行，或由芯片系统或其他功能模块执行，该芯片系统或功能模块能够实现第一网络设备的功能。示例性地，所述第一网络设备为接入网设备，例如基站。该方法包括：向终端设备发送切换命令，所述切换命令包括第一指示信息和第二指示信息，所述第一指示信息用于指示重建PDCP层或小区切换，所述第二指示信息用于指示继续使用第三缓存，所述第三缓存用于所述终端设备对基于第一缓存或第二缓存压缩的数据包进行解压缩；重建PDCP层，且不重置所述第一缓存，所述第一缓存用于所述第一网络设备对数据包进行压缩。
结合第九方面，在第九方面的第一种可选的实施方式中，所述方法还包括：向第二网络设备发送指示信息，所述指示信息用于指示所述第一缓存的内容，所述第一缓存的内容用于更新第二缓存，所述第二缓存用于所述第二网络设备对数据包进行压缩，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备。
结合第九方面或第九方面的第一种可选的实施方式，在第九方面的第二种可选的实施方式中，所述方法还包括：向第二网络设备发送第一消息，所述第一消息用于询问是否支持所述终端设备继续使用第三缓存，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备；从所述第二网络设备接收第二消息，所述第二消息用于指示支持所述终端设备继续使用所述第三缓存。
结合第九方面，在第九方面的第三种可选的实施方式中，所述方法还包括：从所述终端设备接收状态报告，所述状态报告用于指示所述终端设备已接收的压缩数据包。
结合第九方面的第三种可选的实施方式，在第九方面的第四种可选的实施方式中，所述方法还包括：从第一个未确定成功接收的压缩数据包开始，按照压缩数据包的序号升序的顺序向所述终端设备发送N个压缩数据包，N为正整数。
结合第九方面的第四种可选的实施方式，在第九方面的第五种可选的实施方式中，从第一个未确定成功接收的压缩数据包开始，按照压缩数据包的序号升序的顺序向所述终端设备发送N个压缩数据包，包括：对所述N个压缩数据包进行完整性保护以及加密处理；向所述终端设备发送处理后的N个压缩数据包。
结合第九方面的第四种可选的实施方式或第九方面的第五种可选的实施方式，在第九方面的第六种可选的实施方式中，所述N个压缩数据包中序号最小的数据包是所述终端设备未成功接收的数据包中序号最小的数据包。
结合第九方面的第四种可选的实施方式或第九方面的第五种可选的实施方式或第九方面的第六种可选的实施方式，在第九方面的第七种可选的实施方式中，所述N个压缩数据包不包括所述终端设备已接收的压缩数据包。
结合第九方面或第九方面的第一种可选的实施方式至第九方面的第七种可选的实施方式中的任一种可选的实施方式，在第九方面的第八种可选的实施方式中，所述方法还包括：从所述终端设备接收能力信息，所述能力信息用于指示所述终端设备支持继续使用所述第三缓存。
关于第九方面或各种可选的实施方式所带来的技术效果，可参考对于第一方面或相应实施方式的技术效果的介绍，和/或，参考对于第二方面或相应实施方式的技术效果的介绍，和/或，参考对于第三方面或相应实施方式的技术效果的介绍。
其中，第九方面所述的方法所涉及的是下行压缩过程。
第十方面，提供一种通信装置。所述通信装置可以为上述第一至第九方面中的任意一方面所述的终端设备。所述通信装置具备上述终端设备的功能。所述终端设备例如为基站，或为基站中的基带装置。一种可选的实现方式中，所述通信装置包括基带装置和射频装置。另一种可选的实现方式中，所述通信装置包括处理单元(有时也称为处理模块)和收发单元(有时也称为收发模块)。收发单元能够实现发送功能和接收功能，在收发单元实现发送功能时，可称为发送单元(有时也称为发送模块)，在收发单元实现接收功能时，可称 为接收单元(有时也称为接收模块)。发送单元和接收单元可以是同一个功能模块，该功能模块称为收发单元，该功能模块能实现发送功能和接收功能；或者，发送单元和接收单元可以是不同的功能模块，收发单元是对这些功能模块的统称。
其中，所述收发单元(或，所述发送单元)，用于发送M个压缩数据包，所述M个压缩数据包是基于第一缓存对M个数据包压缩得到的，M为正整数；
所述处理单元，用于重建PDCP层，且不重置所述第一缓存；
所述收发单元(或，所述发送单元)，还用于发送N个压缩数据包，所述N个压缩数据包是所述M个压缩数据包中的部分或全部，N为小于或等于M的正整数。
或者，
所述收发单元(或，所述接收单元)，用于接收K个压缩数据包，所述K个压缩数据包是基于第一缓存对K个数据包压缩得到的；
所述处理单元，用于重建PDCP层，且不重置第三缓存；
所述收发单元(或，所述接收单元)，还用于接收N个压缩数据包，所述N个压缩数据包是基于第二缓存对N个数据包压缩的，K和N均为正整数；
所述处理单元，还用于基于所述第三缓存对所述K个压缩数据包和所述N个压缩数据包解压缩，或，基于所述第三缓存对所述N个压缩数据包解压缩。
或者，
所述收发单元(或，所述接收单元)，用于接收切换命令，所述切换命令包括第一指示信息和第二指示信息，所述第一指示信息用于指示重建PDCP层或小区切换，所述第二指示信息用于指示所述终端设备继续使用第一缓存，所述第一缓存用于所述终端设备对数据包进行压缩；
所述处理单元，用于重建PDCP层，且不重置所述第一缓存。
在一种可选的实现方式中，所述通信装置还包括存储单元，所述处理单元用于与所述存储单元耦合，并执行所述存储单元中的程序或指令，使能所述通信装置执行上述第一至第九方面中的任意一方面所述的终端设备的功能。
第十一方面，提供一种通信装置。所述通信装置可以为上述第一至第九方面中的任意一方面所述的第一网络设备。所述通信装置具备上述第一网络设备的功能。所述第一网络设备例如为基站，或为基站中的基带装置。一种可选的实现方式中，所述通信装置包括基带装置和射频装置。另一种可选的实现方式中，所述通信装置包括处理单元(有时也称为处理模块)和收发单元(有时也称为收发模块)。收发单元的实现方式可参考第四方面的介绍。
其中，所述收发单元(或，所述接收单元)，用于从终端设备接收K个压缩数据包，所述K个压缩数据包是基于第一缓存对K个数据包压缩得到的，K为正整数；
所述处理单元，用于重建PDCP层，且不重置第二缓存，所述第二缓存用于所述第一网络设备对基于所述第一缓存压缩的数据包进行解压缩。
或者，
所述收发单元(或，所述接收单元)，用于从第一网络设备接收K个压缩数据包，所述K个压缩数据包是基于第一缓存对K个数据包压缩得到的，所述第二网络设备是终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；
所述收发单元(或，所述接收单元)，还用于从所述第一网络设备接收指示信息，所述指示信息用于指示第二缓存的内容，所述第二缓存用于所述第一网络设备对基于所述第一缓存压缩的数据包进行解压缩；
所述处理单元，用于根据所述第二缓存的内容更新第三缓存，所述第三缓存用于所述第二网络设备对基于所述第一缓存压缩的数据包进行解压缩。
或者，
所述收发单元(或，所述发送单元)，用于向终端设备发送M个压缩数据包，所述M个压缩数据包是基于第一缓存对M个数据包压缩得到的，M为正整数；
所述处理单元，用于重建PDCP层，且不重置所述第一缓存。
或者，
所述收发单元(或，所述接收单元)，用于从第一网络设备接收指示信息，所述指示信息用于指示第一缓存的内容，所述第一缓存用于所述第一网络设备对数据包进行压缩，所述第二网络设备是终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；
所述处理单元，用于根据所述第一缓存的内容更新第二缓存，所述第二缓存用于所述第二网络设备对数据包进行压缩。
或者，
所述收发单元(或，所述发送单元)，用于向终端设备发送切换命令，所述切换命令包括第一指示信息和第二指示信息，所述第一指示信息用于指示重建PDCP层或小区切换，所述第二指示信息用于指示继续使用第一缓存，所述第一缓存用于所述终端设备对数据包进行压缩；
所述处理单元，用于重建PDCP层，且不重置第二缓存，所述第二缓存用于所述第一网络设备对基于所述第一缓存压缩的数据包进行解压缩。
或者，
所述收发单元(或，所述发送单元)，用于向终端设备发送切换命令，所述切换命令包括第一指示信息和第二指示信息，所述第一指示信息用于指示重建PDCP层或小区切换，所述第二指示信息用于指示继续使用第三缓存，所述第三缓存用于所述终端设备对基于第一缓存或第二缓存压缩的数据包进行解压缩；
所述处理单元，用于重建PDCP层，且不重置所述第一缓存，所述第一缓存用于所述第一网络设备对数据包进行压缩。
在一种可选的实现方式中，所述通信装置还包括存储单元，所述处理单元用于与所述存储单元耦合，并执行所述存储单元中的程序或指令，使能所述通信装置执行上述第一至第九方面中的任意一方面所述的第一网络设备或第二网络设备的功能。
第十二方面，提供一种计算机可读存储介质，所述计算机可读存储介质用于存储计算机程序或指令，当其被运行时，使得上述各方面中终端设备、第一网络设备或第二网络设备所执行的方法被实现。
第十三方面，提供一种包含指令的计算机程序产品，当其在计算机上运行时，使得上述各方面所述的方法被实现。
附图说明
图1为LTE系统中数据包的压缩和解压缩过程的示意图；
图2为LTE系统中终端设备发生小区切换时终端设备和基站之间数据包传输过程的示意图；
图3和图4为本申请实施例的两种应用场景示意图；
图5为本申请实施例涉及的UDC技术的示意图；
图6为数据包的计数值的构成示意图；
图7为本申请实施例提供的第一种通信方法的流程图；
图8为本申请实施例中终端设备重传部分压缩数据包的示意图；
图9为本申请实施例中终端设备对数据包进行压缩的示意图；
图10为本申请实施例提供的第二种通信方法的流程图；
图11为本申请实施例提供的第三种通信方法的流程图；
图12为本申请实施例提供的第四种通信方法的流程图；
图13为本申请实施例提供的通信装置的一种示意性框图；
图14为本申请实施例提供的终端设备的一种示意性框图；
图15为本申请实施例提供的网络设备的一种示意性框图。
具体实施方式
为了使本申请实施例的目的、技术方案和优点更加清楚，下面将结合附图对本申请实施例作进一步地详细描述。
本申请实施例中，终端设备是一种具有无线收发功能的设备，可以是固定设备，移动设备、手持设备(例如手机)、穿戴设备、车载设备，或内置于上述设备中的无线装置(例如，通信模块，调制解调器，或电路系统等)。所述终端设备用于连接人，物，机器等，可广泛用于各种场景，例如包括但不限于以下场景：蜂窝通信、设备到设备通信(device-to-device，D2D)、车到一切(vehicle to everything，V2X)、机器到机器/机器类通信(machine-to-machine/machine-type communications，M2M/MTC)、物联网(internet of things，IoT)、虚拟现实(virtual reality，VR)、增强现实(augmented reality，AR)、工业控制(industrial control)、无人驾驶(self driving)、远程医疗(remote medical)、智能电网(smart grid)、智能家具、智能办公、智能穿戴、智能交通，智慧城市(smart city)、无人机、机器人等场景的终端设备。所述终端设备有时可称为用户设备(user equipment，UE)、终端、接入站、UE站、远方站、无线通信设备、或用户装置等等。
本申请实施例中的网络设备，例如包括接入网设备，和/或核心网设备。所述接入网设备为具有无线收发功能的设备，用于与所述终端设备进行通信。所述接入网设备包括但不限于上述通信系统中的基地收发站(BTS)，节点B(Node B)，演进节点B(eNodeB/eNB，或gNodeB/gNB)、收发点(transmission reception point，TRP)，第三代合作伙伴计划(3rd generation partnership project，3GPP)后续演进的基站，无线保真(wireless fidelity，WiFi)系统中的接入节点，无线中继节点，无线回传节点等。所述基站可以是：宏基站，微基站，微微基站，小站，中继站等。多个基站可以支持上述提及的同一种接入技术的网络，也可以支持上述提及的不同接入技术的网络。基站可以包含一个或多个共站或非共站的传输接 收点。网络设备还可以是云无线接入网络(cloud radio access network，CRAN)场景下的无线控制器、集中单元(centralized unit，CU)，和/或分布单元(distributed unit，DU)。网络设备还可以是服务器，可穿戴设备，或车载设备等。例如，车到一切(vehicle to everything，V2X)技术中的网络设备可以为路侧单元(road side unit，RSU)。以下对接入网设备以为基站为例进行说明。所述通信系统中的多个网络设备可以为同一类型的基站，也可以为不同类型的基站。基站可以与终端设备进行通信，也可以通过中继站与终端设备进行通信。终端设备可以与不同接入技术中的多个基站进行通信。所述核心网设备用于实现移动管理，数据处理，会话管理，策略和计费等功能。不同接入技术的系统中实现核心网功能的设备名称可以不同，本申请实施例并不对此进行限定。以5G系统为例，所述核心网设备包括：访问和移动管理功能(access and mobility management function，AMF)、会话管理功能(session management function，SMF)、或用户面功能(user plane function，UPF)等。
本申请实施例中，用于实现网络设备功能的通信装置可以是网络设备，也可以是能够支持网络设备实现该功能的装置，例如电路系统，该装置可以被安装在网络设备中。在本申请实施例提供的技术方案中，以用于实现网络设备的功能的装置是网络设备为例，描述本申请实施例提供的技术方案。
本申请实施例中，对于名词的数目，除非特别说明，表示“单数名词或复数名词”，即"一个或多个”。“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B的情况，其中A,B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。例如，A/B，表示：A或B。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a,b,或c中的至少一项(个)，表示：a,b,c,a和b,a和c,b和c,或a和b和c，其中a,b,c可以是单个，也可以是多个。
本申请实施例提及“第一”、“第二”等序数词是用于对多个对象进行区分，不用于限定多个对象的大小、内容、顺序、时序、应用场景、优先级或者重要程度等。例如，第一缓存和第二缓存，可以是同一个缓存，也可以是不同的缓存，且，这种名称也并不是表示这两个缓存的内容、优先级、应用场景或者重要程度等的不同。
请参考图1，为LTE系统中的数据包压缩和解压缩的过程。图1中，上面两行的PDCP和RLC是指发送端的PDCP层和RLC层，以缓存大小是2个数据包为例，每个虚线框就表示缓存所包括的内容，另外虚线框中有画“/”的方框，表示缓存中包括的预设的信息。每个数据包都基于当前的缓存所包括的内容进行压缩。图1中下面两行的PDCP和RLC是指接收端的PDCP层和RLC层。在AM模式下，因为RLC层支持数据重传机制，因此虽然发送端是按照顺序发送压缩数据包，但接收端接收到的压缩数据包可能存在乱序的现象。在LTE系统中，接收端的RLC层会对接收到的压缩数据包进行排序，再将排序后的压缩数据包递交给PDCP层。例如图1中，接收端的RLC层对于压缩数据包1、压缩数据包2、压缩数据包3和压缩数据包4的接收顺序是压缩数据包3、压缩数据包4、压缩数据包2和压缩数据包1，那么在接收压缩数据包1后，RLC层对这4个压缩数据包进行排序，再按照正常的顺序将这4个压缩数据包递交给PDCP层，PDCP层接收这4个压缩数据包后就对这4个压缩数据包依次通过UDC协议栈进行解压缩。之后，接收端接收了压缩数据包5，接收端的RLC层将压缩数据包5递交给PDCP层，PDCP层对压缩数据包5进行解 压缩。之后，接收端又接收了压缩数据包6、压缩数据包7和压缩数据包8，但接收端对于这3个压缩数据包的接收顺序是压缩数据包8、压缩数据包7、压缩数据包6，那么在接收压缩数据包6后，接收端的RLC层对这3个压缩数据包进行排序，再将排序后的3个压缩数据包递交给PDCP层，PDCP层接收这3个压缩数据包后，依次通过UDC协议栈进行对这3个压缩数据包进行解压缩。例如，PDCP层对压缩数据包1解压缩，依据的是压缩缓存中包括的预设的信息，PDCP层对压缩数据包2进行解压缩，依据的是压缩缓存中包括的预设的信息以及压缩数据包1解压缩后得到的信息，PDCP层对压缩数据包3进行解压缩，依据的是压缩数据包1解压缩后得到的信息以及压缩数据包2解压缩后得到的信息(因为以缓存能够容纳两个数据包的内容为例，因此认为预设的信息已经被挤出了缓存)，等等，以此类推。其中，图1中出现的数据包的序号(或，压缩数据包的序号)均为PDCP层的序列号(sequence number，SN)，或该序号还可以理解为该数据包PDCP层的计数(count)值。
通常情况下，接收端的PDCP层将按顺序收到压缩数据包，保证接收端的缓存和发送端的缓存对齐，实现按序解压。
在LTE系统中，当终端设备发生小区切换时，基站的无线链路控制(radio link control，RLC)层发生重建，如果RLC层已有接收的乱序的压缩数据包，或者说RLC层还有数据包尚未接收，则RLC层不再等待接收尚未接收的压缩数据包，而是会将已接收的压缩数据包递交给PDCP层。例如参考图2，基站(接收端)的RLC层在发生重建时，已接收了压缩数据包3、4、5、7，尚未接收压缩数据包1、2、6，则RLC层会将压缩数据包3、4、5、7递交给PDCP层。其中，压缩数据包0是RLC已接收且已成功解压缩的，压缩数据包1解压得到的数据包0已递交给了PDCP层。PDCP层接收压缩数据包3、4、5、7后，会对这些压缩数据包进行解压缩。PDCP层在对压缩数据包3进行解压缩时，需要根据压缩数据包2的解压缩结果更新缓存，这样才能对压缩数据包3解压缩成功。但由于PDCP层并未接收压缩数据包2，因此PDCP层会对压缩数据包3解压缩失败，同理，PDCP层对压缩数据包4、5、7也会解压缩失败，则PDCP层会丢弃压缩数据包3、4、5、7。另外，基站的RLC层在接收压缩数据包后，会向终端设备发送混合自动重传请求(hybrid automatic repeat request，HARQ)-应答(ACK)信息，对于已接收的压缩数据包，基站的RLC层会向终端设备发送肯定应答(ACK)。例如RLC层在发生重建时尚未接收压缩数据包1，那么RLC层就不会向终端设备发送压缩数据包1的ACK。
终端设备(发送端)在进行小区切换完毕后，可以向基站重传压缩数据包，例如终端设备从第一个未收到ACK的压缩数据包开始顺序重传。例如终端设备收到了压缩数据包3、4、5、7的ACK，未收到压缩数据包1、2、6的ACK，则终端设备会重传压缩数据包1～压缩数据包7。终端设备在小区切换过程中会重建PDCP层，也会重置终端设备对应于UDC的缓存及UDC协议栈等，则终端设备会根据重置的缓存重新对数据包进行压缩。终端设备之前发送给基站的压缩数据包1～压缩数据包7都是根据重置前的缓存对相应数据包进行压缩得到的，而此时终端设备会根据重置的缓存重新再次对这些数据包进行压缩，以得到压缩数据包1～压的数据包7，终端设备再将这些压缩数据包发送给基站。可见，对于同一个数据包，终端设备需要进行两次压缩。而多次压缩过程显然增加了终端设备的处理时间，尤其是数据包较多的情况下，会在很大程度上降低终端设备的处理效率。
UDC技术目前只存在于LTE系统中，还未引入新无线(new radio，NR)系统。在NR 系统中是否能够使用UDC技术，目前尚无定论。
本申请实施例提供一种通信方法，通过本申请实施例提供的方法，能够在NR系统中应用基于缓存进行数据压缩的技术(例如UDC技术)。而且在本申请实施例中，终端设备在重建PDCP层的情况下，不重置第一缓存，那么如果终端设备需要重传数据包，则终端设备可将之前得到的压缩数据包进行重传即可，无需再次对数据包进行压缩，这样就减少了数据包的压缩次数，减少了终端设备的处理时间，提高了处理效率。而且由于减少了终端设备的工作量，也就减小了终端设备的功耗。如果终端设备作为数据接收端，则终端设备也可以正常处理数据，无需重置缓存，减少了终端设备的工作量，也减小了终端设备的功耗。
本申请实施例提供的技术方案可以应用于LTE系统，例如可以应用于普通的LTE系统或车联网等，例如车到一切(vehicle to everything，V2X)、LTE-V等，或者可以应用于NR系统，例如可以应用于普通的NR系统或车联网等，例如V2X、NR-V等，或者还可以应用于其他类似的通信系统或下一代通信系统。
请参见图3，为本申请实施例的一种应用场景。在图3中包括一个网络设备以及一个终端设备。其中，该网络设备例如工作在演进的通用移动通信系统陆地无线接入(evolved UMTS terrestrial radio access，E-UTRA)系统中，或者工作在NR系统中。例如终端设备在进行小区切换前和小区切换后，都是接入该网络设备。
请参考图4，为本申请实施例的另一种应用场景。在图4中包括两个网络设备以及一个终端设备，例如网络设备1是终端设备进行小区切换前接入的网络设备，网络设备2是终端设备进行小区切换后接入的网络设备。其中，该网络设备1或网络设备2例如工作在演进的通用移动通信系统陆地无线接入(evolved UMTS terrestrial radio access，E-UTRA)系统中，或者工作在NR系统中，且网络设备1和网络设备2所工作的系统可以相同也可以不同。
图3或图4中的网络设备例如为基站。其中，网络设备在不同的系统对应不同的设备，例如在4G系统中可以对应eNB，在5G系统中对应5G中的网络设备，例如gNB。在5G系统中网络设备也可以是LTE网络设备与NR网络设备混合组网的设备，与终端设备组成混合空口双连接(mixed radio-dual connectivity，MR-DC)。当然本申请实施例所提供的技术方案也可以应用于未来的移动通信系统中，因此图3或图4中的网络设备也可以对应未来的移动通信系统中的网络设备。图3和图4都以网络设备是基站为例，实际上参考前文的介绍，网络设备还可以是RSU等设备。
考虑一种本申请实施例的实际应用场景。当用户持有终端设备，要进行VoLTE/新无线语音承载(voice over new radio，VoNR)电话或数据上网(如发起直播，玩游戏上网)等操作时，需要接入网络。在接入网络之初，终端设备一般需要向基站上报是否支持数据压缩的能力。当确定终端设备具备支持数据压缩的能力时，基站可以根据用户发起的业务，决定是否给终端设备配置数据压缩的相关参数(例如配置对应的承载支持UDC功能及其激活状态)。当终端设备被基站配置了可以进行数据压缩时，例如可以进行UDC，则终端设备在进行上行传输时，例如发起VoLTE/VoNR电话或者发起直播或者玩实时游戏等的过程中，可以采用UDC方式。在这种情况下，终端设备可以使用本申请实施例所提供的方法来进行UDC，可以减少甚至避免上行数据压缩导致的丢包，节约重复压缩带来的功耗。类似的，如果进行下行数据压缩，也可以采用本申请实施例提供的方法，以减少甚至避免 下行数据压缩导致的丢包。
另外，本申请实施例并不限制于是网络设备和终端设备之间的通信，还可以是网络设备与网络设备之间的通信，或者也可以是终端设备与终端设备之间的通信等。
下面结合附图介绍本申请实施例提供的技术方案。需要注意的是，在本申请的各个实施例对应的附图中，凡是用虚线表示的步骤均为可选的步骤。另外，本申请的各个实施例均以NR系统为例。
在介绍本申请提供的实施例之前，先介绍本申请的各个实施例所涉及的UDC技术。
UDC是终端设备作为发送端对数据包进行压缩，网络设备作为接收端对数据包进行解压缩，而压缩和解压缩均是基于发送端和接收端共同维护相同的缓存状态来进行的。缓存状态，可以是指缓存所包括的内容(或者说，缓存所包括的信息)。发送端在对数据包进行压缩时，基于缓存当前的状态进行压缩，在压缩成功后，发送端会将当前压缩数据包在压缩之前的原始信息从缓存的后端放入该缓存，进行缓存的更新。其中，对于第一个数据包，在压缩时缓存中可能并不包括之前的数据包的信息，那么发送端可以基于预设的信息进行压缩，预设的信息，例如为预制字典等。例如可参考图5，缓存中包括“abc”，“abc”例如为预制字典。发送端需要对数据包“def”进行压缩时，可以基于“abc”进行压缩，对数据包“def”压缩后得到压缩数据包1，而发送端可以将“def”从缓存的后端放入该缓存。之后，发送端需要对数据包“ghijkl”进行压缩，则可以基于buffer中的“abcdef”来压缩，也就是说，每次都是基于缓存中的全部内容来进行压缩。对数据包“ghijkl”压缩后得到压缩数据包2，而发送端可以将数据包“ghijkl”从缓存的后端放入缓存。由于buffer的存储空间有限，因此按照先入先出(first in first out，FIFO)的原则，“abcd”会被挤出缓存，那么，如果发送端还需要再对其他的数据包进行压缩，就会基于缓存中包括的“efghijkl”来进行压缩。对于接收端来说，在接收压缩数据包1后，可以基于缓存中的预制字典“abc”对压缩数据包1进行解压缩，得到数据包“def”，将数据包“def”从缓存的后端放入缓存。在接收压缩数据包2后，接收端可以基于缓存中的信息“abcdef”对压缩数据包2进行解压缩，得到数据包“ghijkl”，将数据包“ghijkl”从缓存的后端放入缓存，则“abcd”被挤出缓存。可见，接收端的缓存状态和发送端的缓存状态始终保持一致，这样就可以保证接收端能够正确解压缩。
在本申请的各个实施例中，压缩前的数据包(在下文中也称为数据包)和对应的压缩数据包，其序号可以是相同的。例如，对第一数据包进行压缩可得到第一压缩数据包，第一压缩数据包的序号和第一数据包的序号是相同的；对第二数据包进行压缩可得到第二压缩数据包，第二压缩数据包的序号和第二数据包的序号是相同的。另外，本申请的各个实施例所提供的技术方案，可以应用于UM/AM的数据无线承载(data radio bearer，DRB)的传输，或应用于信令无线承载(signalling radio bearer，SRB)的传输，或DRB中某一个服务质量流(QoS flow)的传输。
在空口传输中，每个数据包都有PDCP层对应的编号。其中，一个数据包在PDCP层的编号可以由两部分构成，这两部分为序列号(sequence number，SN)和超帧号(hyper frame number，HFN)，这两部分合起来就构成数据包的编号，或者说是数据包的计数(count)值。可参考图6，为数据包的计数值的构成示意图。在本申请实施例中所述的数据包的序号，可以是指数据包的序列号，或者是指数据包的计数值。
本申请实施例提供第一种通信方法，请参见图7，为该方法的流程图。在下文的介绍过程中，以该方法应用于图3所示的网络架构为例。下文所述的终端设备例如为图3所示 的网络架构中的终端设备，下文所述的第一网络设备例如为图3所示的网络架构中的网络设备。
S701、终端设备向第一网络设备发送能力信息，相应的，第一网络设备接收来自终端设备的能力信息。
例如终端设备可在随机接入过程中向第一网络设备发送该能力信息，或者终端设备可以在随机接入成功后向第一网络设备发送该能力信息。该能力信息可指示终端设备的能力，例如该能力信息指示终端设备可以支持UDC。又例如，该能力信息可指示支持继续使用第一缓存，这表明终端设备支持继续使用第一缓存的功能(该功能也可称为缓存继续(buffer continue))，或指示不支持继续使用第一缓存。buffer continue可以理解为是在重建PDCP层时不重置与数据压缩/解压缩功能对应的缓存，因此，该能力信息也可以指示在重建PDCP层时支持不重置第一缓存，或指示在重建PDCP层时不支持不重置第一缓存。可选的，除此之外，该能力信息还可以指示终端设备其他方面的能力，例如指示终端设备支持的天线数量等，对此不做限制。第一缓存由终端设备维护，用于压缩数据包，或者说，终端设备可基于第一缓存对数据包进行压缩。
第一网络设备根据该能力信息就能明确终端设备是否支持继续使用第一缓存。如果终端设备支持继续使用第一缓存，第一网络设备就可以指示终端设备继续使用第一缓存，如果终端设备不支持继续使用第一缓存，第一网络设备可不指示终端设备继续使用第一缓存或指示终端设备重置第一缓存。或者，终端设备也可以不发送能力信息，第一网络设备可以根据其他因素确定是否指示终端设备继续使用第一缓存，或者终端设备是否继续使用第一缓存也可以通过协议规定，因此S701是可选的步骤。
S702、终端设备向第一网络设备发送M个压缩数据包，相应的，第一网络设备接收来自终端设备的K个压缩数据包。M为正整数，K为小于或等于M的正整数。K个压缩数据包可以是M个压缩数据包中的部分或全部，或者说K个压缩数据包是M个压缩数据包的子集。
之所以第一网络设备是接收K个压缩数据包而不是接收M个压缩数据包，是考虑到了丢包的情况，例如可能有M-K个压缩数据包在传输过程中丢失，未被第一网络设备正确接收。K个压缩数据包的序号可能连续，也可能不连续。可选的，K个压缩数据包的序号与第一网络设备已成功解压缩的数据包之间的序号是不连续的。例如，M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，则K个压缩数据包的序号不连续，且第一网络设备已成功解压缩的序号最大的压缩数据包为压缩数据包0，则K个压缩数据包的序号与第一网络设备已成功解压缩并向上层递交的最后一个的数据包之间的序号也不连续。又例如，M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、6，则K个压缩数据包的序号连续，第一网络设备已成功解压缩的序号最大的压缩数据包为压缩数据包0，则K个压缩数据包的序号与第一网络设备已成功解压缩的数据包之间的序号不连续。
M个压缩数据包是终端设备基于第一缓存对M个数据包压缩得到的，压缩数据包和数据包为一一对应的关系。第一缓存为终端设备对数据包进行压缩的缓存，例如终端设备可采用UDC技术，基于第一缓存对数据包进行压缩。第一缓存例如对应于第一无线承载，第一无线承载可包括该终端设备的全部或部分无线承载，所述的无线承载例如为DRB或SRB等。或者，第一缓存例如对应于DRB中的某一个或多个QoS flow。
例如在发送M个压缩数据包之前，终端设备尚未向第一网络设备发送压缩数据包，那么终端设备在对M个压缩数据包进行压缩之前，第一缓存例如包括预制字典，即第一缓存中填充了预制字典。终端设备基于该预制字典对M个数据包中的数据包1进行压缩，得到压缩数据包1。接着，终端设备基于数据包1的内容更新第一缓存，再基于更新的第一缓存对M个数据包中的数据包2进行压缩，得到压缩数据包2，以此类推，直到得到M个压缩数据包。关于此过程的示例，也可参考图5。
第一网络设备可以向终端设备发送K个压缩数据包的反馈信息，以表示第一网络设备已接收了K个压缩数据包。例如第一网络设备的RLC层每接收一个压缩数据包，就可向终端设备发送该压缩数据包的ACK，则第一网络设备共可以向终端设备发送K个ACK，K个ACK对应K个压缩数据包，终端设备接收K个ACK后就可以获知第一网络设备接收了K个压缩数据包。
可选的，第一网络设备的PDCP层还可向终端设备发送状态报告，该状态报告可指示第一网络设备已接收的压缩数据包，对于本申请实施例来说，该状态报告就可指示K个压缩数据包，终端设备接收该状态报告后，就可以获知第一网络设备接收了K个压缩数据包。例如，该状态报告可通过比特地图(bitmap)实现，该bitmap包括的比特数可以为M，M个比特与M个压缩数据包一一对应。如果第一网络设备接收了一个压缩数据包，则该压缩数据包对应的比特就置为“1”，如果第一网络设备未接收一个压缩数据包，则该压缩数据包对应的比特就置为“0”，这样可以使得终端设备很快明确第一网络设备接收了哪些压缩数据包。又例如，该状态报告可包括第一网络设备已接收的压缩数据包的序号，和/或，包括第一网络设备未接收的压缩数据包的序号，这样都能使得终端设备明确第一网络设备接收了哪些压缩数据包。
需要注意的是，终端设备可对压缩数据包进行相应处理后再发送。例如，终端设备对压缩数据包进行完整性保护以及加密处理(例如在PDCP层进行相应处理)，将处理后的压缩数据包递交给终端设备的底层(例如RLC层，媒体接入控制(media access control，MAC)层，或物理层等)，再由终端设备的底层发送处理后的压缩数据包。终端设备发送M个压缩数据包，后文中将要涉及的终端设备发送N个压缩数据包，均可以采用类似的方式，不多赘述。
S703、第一网络设备向终端设备发送切换命令，相应的，终端设备接收来自第一网络设备的切换命令。
例如，该切换命令包括第一指示信息，第一指示信息可指示重建PDCP层，或者指示小区切换。可选的，该切换命令还可包括第二指示信息，第二指示信息可指示继续使用第一缓存，或者，第二指示信息可指示在重建PDCP时不重置第一缓存。在这种情况下，如果该切换命令包括第二指示信息，则终端设备在重建PDCP层的情况下可继续使用第一缓存，而如果该切换命令不包括第二指示信息，则终端设备在重建PDCP层的情况下不会继续使用第一缓存，例如终端设备在重建PDCP层的情况下会重置第一缓存。或者，在这种情况下，第二指示信息指示在重建PDCP时是否重置第一缓存。或者，在这种情况下，第二指示信息的值指示在重建PDCP时是否重置第一缓存。
或者，第二指示信息也可以不包括在该切换命令中，第一网络设备可以通过其他的消息向终端设备发送第二指示信息。如是这种情况，那么第一网络设备可以在S703之前向终端设备发送第二指示信息，或者在S703之后向终端设备发送第二指示信息，或者第一 网络设备也可以同时向终端设备发送切换命令和第二指示信息。在这种情况下，如果终端设备接收了第二指示信息，则终端设备在重建PDCP层的情况下可继续使用第一缓存，而如果终端设备未接收第二指示信息，则终端设备在重建PDCP层的情况下不会继续使用第一缓存，例如终端设备在重建PDCP层的情况下可重置第一缓存。
在第一网络设备发送第二指示信息的情况下，第一网络设备也支持继续使用第二缓存。第二缓存是与第一缓存相对应的，由第一网络设备维护，例如第一网络设备可根据第二缓存对基于第一缓存得到的压缩数据包(或者说，基于第一缓存压缩的数据包)进行解压缩。在第一网络设备不发送第二指示信息的情况下，第一网络设备可以支持继续使用第二缓存，也可以不支持继续使用第二缓存，无论第一网络设备是否支持继续使用第二缓存，由于第一网络设备未发送第二指示信息，则第一网络设备在重建PDCP层的情况下不会继续使用第二缓存，而是会重置第二缓存，以与终端设备的行为保持一致。
或者，例如协议规定继续使用第一缓存，或者协议规定在重建PDCP时不重置第一缓存，则第一网络设备也可以不发送第二指示信息。在这种情况下，网络设备可根据协议确定在重建PDCP层时继续使用第二缓存，终端设备也可根据协议确定在重建PDCP层时继续使用第一缓存。
除了进行小区切换外，终端设备还可能在其他情况下重建PDCP层，因此S703是可选的步骤。
S704、终端设备重建PDCP层，且不重置第一缓存。
终端设备在进行小区切换时，可重建PDCP层。或者，终端设备也可以在除了小区切换外的其他事件触发下重建PDCP层，因此S703是可选的步骤。
如果终端设备接收了第二指示信息，或者协议规定继续使用第一缓存，则终端设备在重建PDCP层时可不重置第一缓存。而如果终端设备未接收第二指示信息，且协议也未规定继续使用第一缓存，则终端设备在重建PDCP层时可以重置第一缓存。终端设备重置第一缓存，例如包括将第一缓存的内容清空，且在清空后的第一缓存内添加预制字典。在本申请的各个实施例中，预制字典的内容例如与业务相关，在设备所进行的业务不同时，预制字典可以相同，或者也可以不同。或者，预制字典的内容也可以与其他因素相关，具体的不做限制，后文也不再多赘述。本申请实施例以终端设备在重建PDCP层时不重置第一缓存为例。
S705、第一网络设备重建PDCP层，且不重置第二缓存。
如果终端设备进行小区切换，则第一网络设备也会重建PDCP层。在本申请实施例中，终端设备进行小区切换前和小区切换后接入的都是第一网络设备，例如终端设备是从第一网络设备提供的第一小区切换到了第一网络设备提供的第二小区。如果第一网络设备确定继续使用第二缓存，那么第一网络设备在重建PDCP层时不重置第二缓存。而如果第一网络设备确定不继续使用第二缓存，那么第一网络设备在重建PDCP层时可以重置第二缓存。第一网络设备重置第二缓存，例如包括将第二缓存的内容清空，且在清空后的第二缓存内添加预制字典。对于第一网络设备和终端设备来说，由于需要保持缓存状态一致，因此用于重置第一缓存的预制字典和用于重置第二缓存的预制字典可以是相同的。本申请实施例以第一网络设备在重建PDCP层时不重置第二缓存为例。
S704可能发生在S705之前，或者可能发生在S705之后，或者也可能与S705同时发生。
S706、终端设备向第一网络设备发送N个压缩数据包，相应的，第一网络设备接收来自终端设备的N个压缩数据包。N个压缩数据包是M个压缩数据包中的部分或全部，例如N为小于或等于M的整数。
终端设备在进行小区切换完毕后，或者终端设备在PDCP层重建完毕后，未切换网络设备，可以向第一网络设备重发N个压缩数据包。终端设备从第一网络设备的第一个未确定成功接收的压缩数据包开始，按照压缩数据包的序号升序的顺序发送N个压缩数据包。例如N个压缩数据包中的第一个压缩数据包(或者说，N个压缩数据包中序号最小的压缩数据包)，可以是第一网络设备第一个未成功接收的压缩数据包(或者说，是第一网络设备未成功接收的数据包中序号最小的压缩数据包)。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1～压缩数据包7，则N个压缩数据包中的第一个压缩数据包为压缩数据包1，压缩数据包1就是第一网络设备第一个未成功接收的压缩数据包。
在如上的示例中，N＝M，终端设备相当于重发了M个压缩数据包，这样可以提高第一网络设备获得压缩数据包的成功率。可选的，如果第一网络设备向终端设备发送了状态报告，该状态报告指示了第一网络设备已接收的压缩数据包，那么对于第一网络设备已接收的压缩数据包，终端设备可以不再发送，而只需发送第一网络设备未接收的压缩数据包，在这种情况下，N个压缩数据包就可以不包括第一网络设备已接收的压缩数据包。例如，M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，第一网络设备向终端设备发送的状态报告指示K个压缩数据包，则终端设备发送的N个压缩数据包例如压缩数据包1、2、6，而对于压缩数据包3、4、5、7，终端设备可不再发送，这样可以减少终端设备重发的数据量，节省传输开销。
可参考图8，终端设备的PDCP层发送的M个压缩数据包例如为压缩数据包1～压缩数据包7，第一网络设备的PDCP层接收了压缩数据包3、4、5、7，并未接收压缩数据包1、2、6，另外终端设备的PDCP层在发送M个压缩数据包之前还向第一网络设备发送了压缩数据包0，第一网络设备的PDCP层接收了压缩数据包0，且也对压缩数据包0解压缩成功，得到了数据包0，则第一网络设备的PDCP层将数据包0递交给PDCP层的上层，例如服务数据适配协议(service data adaptation protocol，SDAP)层。第一网络设备的PDCP层向终端设备的PDCP层发送状态报告，该状态报告指示第一网络设备接收了压缩数据包3、4、5、7。例如该状态报告通过bitmap实现，该bitmap可包括7个比特，该bitmap例如为1011100，从低位到高位依次对应压缩数据包1～压缩数据包7，第一网络设备接收了压缩数据包3、4、5、7，则这些压缩数据包对应的比特取值为“1”，第一网络设备未接收压缩数据包1、2、6，则这些压缩数据包对应的比特取值为“0”。终端设备接收该状态报告后，终端设备的PDCP层向第一网络设备重发压缩数据包1、2、6，而不必再重新发送压缩数据包3、4、5、7，以节省上行传输资源。
可再参考图9，为终端设备对数据包1～7进行压缩的过程。图9中的第一行的1～7表示7个PDCP服务数据单元(service data unit，SDU)，也就是7个数据包，即，第一行的1～7表示待压缩的7个数据包。第二行表示终端设备基于第一缓存对数据包1～7压缩后得到的压缩数据包1～7。第三行表示对第二行的压缩数据包1～压缩数据包7按照第一加密方式加密后得到的加密数据包1～加密数据包7，终端设备可向第一网络设备发送这7个加密数据包，该过程可视为终端设备向第一网络设备发送M个压缩数据包，例如M＝7，这7 个加密数据包就是对M个压缩数据包按照第一加密方式加密得到的，第一加密方式是终端设备在进行小区切换前接入的第一小区所对应的加密方式。第四行表示对第二行的压缩数据包1～压缩数据包7按照第二加密方式加密后得到的加密数据包1～加密数据包7，终端设备可向第一网络设备发送这7个加密数据包，该过程可视为终端设备向第一网络设备发送N个压缩数据包，例如N＝7，这7个加密数据包就是对N个压缩数据包按照第二加密方式加密得到的，第二加密方式是终端设备在进行小区切换后接入的第二小区所对应的加密方式。通过图9可以看到，终端设备对于这些数据包的压缩过程只执行了一次，如果需要重传这些压缩数据包，则只需对已得到的压缩数据包按照小区切换后对应的加密方式进行加密即可，无需重新对数据包进行压缩，减少了终端设备的压缩过程，相应提高了终端设备的处理效率。
对于第一网络设备来说，在接收K个压缩数据包后，如果不向终端设备发送状态报告，则第一网络设备可对K个压缩数据包进行解压。由于K个压缩数据包的序号与第一网络设备已成功解压缩的数据包的序号不连续，则第一网络设备对于K个压缩数据包可能会解压失败，那么第一网络设备可丢弃解压失败的K个压缩数据包。终端设备会再向第一网络设备发送N个压缩数据包，终端设备由于未接收状态报告，则N个压缩数据包中序号最小的压缩数据包是第一网络设备未成功接收的压缩数据包中序号最小的压缩数据包，且N个数据包的序号是连续的，例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1～压缩数据包7。这样，即使第一网络设备丢弃了K个压缩数据包，由于终端设备会再次发送N个压缩数据包，N个压缩数据包会包括K个压缩数据包，则第一网络设备还是能够获得K个压缩数据包。继续上述示例，由于第一网络设备获得了压缩数据包1～7，而第一网络设备之前已经对压缩数据包0进行了正确的解压缩，则第二缓存的状态是根据数据包0确定的，那么第一网络设备基于未重置的第二缓存就能对压缩数据包1～压缩数据包7进行正确的解压。
或者，第一网络设备在接收K个压缩数据包后，如果不向终端设备发送状态报告，也可以不对K个压缩数据包进行解压，而是等待来自终端设备的N个压缩数据包。PDCP层可能有去重功能，例如对于压缩数据包3，第一网络设备已经接收过了，且第一网络设备并未丢弃，则如果N个压缩数据包中包括压缩数据包3，第一网络设备接收N个压缩数据包中的压缩数据包3后会丢弃该压缩数据包3，而继续存储之前接收的压缩数据包3。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1～压缩数据包7，则第一网络设备会丢弃所接收的N个压缩数据包中的压缩数据包3、4、5、7。但由于第二缓存并未重置，第一网络设备所存储的压缩数据包3、4、5、7与第一网络设备丢弃的压缩数据包3、4、5、7是一样的，则第一网络设备基于未重置的第二缓存，依然能够对K个压缩数据包3、4、5、7，以及对N个压缩数据包中的压缩数据包1、2、6进行正确的解压，通过这种方式，能够减小第一网络设备的丢包率。
而第一网络设备在接收K个压缩数据包后，如果向终端设备发送了状态报告，则终端设备所发送的N个压缩数据包中可能不再包括K个压缩数据包，如果第一网络设备对K个压缩数据包进行了解压，又因为解压失败丢弃了K个压缩数据包，而终端设备也不再发送K个压缩数据包，会导致第一网络设备无法获得K个压缩数据包，还可能影响第一网络设备对其他压缩数据包的解压。因此，第一网络设备在接收K个压缩数据包后，如果向终 端设备发送了状态报告，则第一网络设备可以不对K个压缩数据包进行解压，而是等待来自终端设备的N个压缩数据包，且因为终端设备不会重复发送相同序号的数据包，因此第一网络设备也无需使用去重功能。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1、2、6，第一网络设备基于未重置的第二缓存，能够对K个压缩数据包3、4、5、7，以及对N个压缩数据包1、2、6进行正确的解压。
S707、第一网络设备基于第二缓存对N个压缩数据包进行解压缩，或，第一网络设备基于第二缓存对N个压缩数据包和K个压缩数据包进行解压缩。
例如，N个压缩数据包中包括了K个压缩数据包，那么可理解为，第一网络设备基于第二缓存对N个压缩数据包进行解压缩。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1～压缩数据包7，则第一网络设备基于第二缓存对压缩数据包1～压缩数据包7进行解压缩。
又例如，N个压缩数据包中包括了K个压缩数据包，那么可理解为，第一网络设备基于第二缓存对N个压缩数据包和K个压缩数据包进行解压缩。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1、2、6，则第一网络设备基于第二缓存对压缩数据包1～压缩数据包7进行解压缩，压缩数据包1～压缩数据包7就是K个压缩数据包和N个压缩数据包的并集。
通过本申请实施例提供的技术方案，可以减少终端设备的压缩次数，提升终端设备的处理效率。如果第一网络设备向终端设备发送状态报告，还可以减少终端设备所发送的数据量，节省传输开销。而且由于终端设备的第一缓存和第一网络设备的第二缓存均未重置，在第一网络设备不向终端设备发送状态报告的情况下，无论第一网络设备在接收K个压缩数据包后对K个压缩数据包是否进行解压缩，第一网络设备都能够获得M个压缩数据包，减少了丢包量。
前文介绍的都是终端设备和第一网络设备不重置缓存的情况，而如果终端设备接收的第二指示信息指示不继续使用第一缓存，或者协议规定不继续使用第一缓存，则终端设备在重建PDCP层时可以重置第一缓存，对于第一网络设备来说也会重置第二缓存。如下简单介绍这种情况下终端设备和第一网络设备的处理方式。
例如继续参考图2，第一网络设备的PDCP层在发生重建时，已接收了压缩数据包3、4、5、7，尚未接收压缩数据包1、2、6。其中，压缩数据包0是PDCP层已接收且已成功解压缩的压缩数据包，PDCP层对压缩数据包0解压缩得到了数据包0。PDCP层接收压缩数据包3、4、5、7后，PDCP的重建指示可以触发对这些压缩数据包进行解压缩，PDCP层对压缩数据包3、4、5、7会解压缩失败，则PDCP层会丢弃压缩数据包3、4、5、7，或者，PDCP的重建指示可以触发PDCP层丢弃乱序的压缩数据包(有一种特殊情况，如果来自发送端的数据包是未经压缩的数据包，则这些数据包即使乱序，也无需丢弃)，即，PDCP层不对压缩数据包3、4、5、7解压缩，而是直接丢弃压缩数据包3、4、5、7。直接丢弃乱序的压缩数据包的方案可以减少接收端的解压缩次数，提高处理效率，节约能耗，避免浪费资源进行无效的解压缩处理。另外，第一网络设备的RLC层在接收压缩数据包后，会向终端设备发送ACK信息，对于已接收的压缩数据包，例如第一网络设备的RLC层会向终端设备发送ACK。后续如果第一网络设备会向终端设备发送PDCP层的反馈报告，则反馈报告既可指示第一网络设备未接收的数据包，也可指示第一网络设备未解压缩成功的 数据包。
终端设备在进行小区切换完毕后，或者在PDCP层重建完毕后，可以向第一网络设备重传压缩数据包，例如终端设备从第一个未收到ACK的压缩数据包开始顺序重传。例如终端设备收到了压缩数据包0、3、4、5、7的ACK，未收到压缩数据包1、2、6的ACK，则终端设备会重传压缩数据包1～压缩数据包7。终端设备在小区切换过程中会重建PDCP层，也会重置第一缓存，则终端设备会根据重置的第一缓存重新对数据包进行压缩。终端设备之前发送给第一网络设备的压缩数据包1～压缩数据包7都是根据重置前的第一缓存对数据包1～数据包7进行压缩得到的，而此时终端设备会根据重置的第一缓存重新再次对数据包1～数据包7进行压缩，以得到压缩数据包1～压缩数据包7，终端设备再将这些压缩数据包发送给第一网络设备。可见，如果不继续使用第一缓存，则对于同一个数据包，终端设备需要进行两次压缩。
在本申请实施例中，可由第一网络设备指示是否继续使用第一缓存，则第一网络设备可根据具体情况相应指示是否继续使用第一缓存，例如对于能力较低的终端设备，第一网络设备可不指示继续使用第一缓存，或者可指示不继续使用第一缓存，以符合终端设备的能力需求；又例如，对于时延要求较高的场景，第一网络设备可指示继续使用第一缓存，终端设备只需压缩一次，节省终端设备的处理时间，从而减小数据包的传输时延。可见，本申请实施例的方案较为灵活。
图7所示的实施例所应用的场景是共站的场景，即，终端设备切换前和切换后接入的都是同一个网络设备。接下来介绍本申请实施例提供的第二种通信方法，该方法可应用于图4所示的网络架构，请参见图10，为该方法的流程图。在该方法中，终端设备在进行小区切换前接入的是第一网络设备，在进行小区切换后接入的是第二网络设备，可理解为，终端设备从第一网络设备提供的第一小区切换到了第二网络设备提供的第二小区，第一网络设备和第二网络设备是不同的网络设备。下文所述的终端设备例如为图4所示的网络架构中的终端设备，下文所述的第一网络设备例如为图4所示的网络架构中的网络设备1，下文所述的第二网络设备例如为图4所示的网络架构中的网络设备2。
S1001、终端设备向第一网络设备发送能力信息，相应的，第一网络设备接收来自终端设备的能力信息。
关于S1001的更多内容，可参考图7所示的实施例中的S701。
S1002、终端设备向第一网络设备发送M个压缩数据包，相应的，第一网络设备接收来自终端设备的K个压缩数据包。M为正整数，K为小于或等于M的正整数。
在本申请实施例中，第一网络设备在接收K个压缩数据包后，可以向终端设备发送K个压缩数据包的反馈信息，例如第一网络设备的RLC层可向终端设备发送K个ACK。可选的，第一网络设备还可以向终端设备发送K个压缩数据包的状态报告，该状态报告指示第一网络设备已接收的压缩数据包，例如指示K个压缩数据包。关于这些内容，可参考图7所示的实施例中的S702。或者，第一网络设备也可以不向终端设备发送K个压缩数据包的状态报告。
关于S1002的更多内容，也可参考图7所示的实施例中的S702。
S1003、第一网络设备向第二网络设备发送第一消息，相应的，第二网络设备接收来自第一网络设备的第一消息。第一消息可用于询问是否在切换后支持终端设备继续使用第一缓存，或者，第一消息可用于询问是否支持终端设备在重建PDCP层时不重置第一缓存。 其中，第一缓存为终端设备维护的用于对数据包进行压缩的缓存，如果第一缓存发生重置，则第二网络设备维护的用于解压缩的第三缓存的内容也需要是重置后的状态，例如在第三缓存中填入预制字典。第三缓存由第二网络设备维护，第二网络设备可根据第三缓存对基于第一缓存压缩的数据包进行解压缩。
第一缓存、第二缓存、第三缓存都是对应的，第一缓存由终端设备维护，终端设备根据第一缓存对数据包进行压缩；第二缓存由第一网络设备维护，终端设备在进行小区切换前接入的是第一网络设备，第一网络设备可基于第二缓存对来自终端设备的压缩数据包(基于第一缓存压缩的数据包)进行解压缩；第三缓存由第二网络设备维护，终端设备在进行小区切换后接入的是第二网络设备，第二网络设备可基于第三缓存对来自终端设备的压缩数据包(基于第一缓存压缩的数据包)进行解压缩。
例如第一消息为切换请求(handover request)消息，可理解为，切换请求消息包括询问信息，该询问信息可用于询问第二网络设备是否支持终端设备继续使用第一缓存。或者第一消息也可以是其他消息。
S1004、第二网络设备向第一网络设备发送第二消息，相应的，第一网络设备接收来自第二网络设备的第二消息。第二消息可指示支持终端设备继续使用第一缓存，或者指示不支持终端设备继续使用第一缓存。或者，第二消息可指示支持终端设备在重建PDCP层时不重置第一缓存，或指示不支持终端设备在重建PDCP层时不重置第一缓存。例如第二消息为切换请求应答(handover request acknowledge)消息，可理解为，切换请求应答消息包括第三指示信息，第三指示信息可指示支持终端设备继续使用第一缓存，或指示不支持终端设备继续使用第一缓存；或者，第三指示信息可指示支持终端设备在重建PDCP层时不重置第一缓存，或指示不支持终端设备在重建PDCP层时不重置第一缓存。或者第二消息也可以是其他消息。
或者，第一网络设备也可以无需获知第二网络设备是否支持终端设备继续使用第一缓存，或者第一网络设备也可以通过其他方式获知第二网络设备是否支持终端设备继续使用第一缓存，因此S1003和S1004是可选的步骤。
S1005、第一网络设备向终端设备发送切换命令，相应的，终端设备接收来自第一网络设备的切换命令。该切换命令可指示终端设备进行小区切换，或指示PDCP进行重建。可选的，该切换命令还可以包括用于指示终端设备继续使用第一缓存或不继续使用第一缓存的信息。
关于S1005的更多内容，可参考图7所示的实施例中的S703。
S1006、终端设备重建PDCP层，且不重置第一缓存。
关于S1006的更多内容，可参考图7所示的实施例中的S704。
S1007、第一网络设备重建PDCP层，且不重置第二缓存。
关于S1007的更多内容，可参考图7所示的实施例中的S705。
S1008、第一网络设备向第二网络设备发送第二缓存的内容，相应的，第二网络设备接收来自第一网络设备的第二缓存的内容。例如，第一网络设备可向第二网络设备发送指示信息，为了与前述的指示信息相区分，该指示信息也可称为第四指示信息，第四指示信息可指示第二缓存的内容。例如第四指示信息包括第二缓存的内容(例如，根据第二缓存的大小，第二缓存的大小的常见配置为2k、4k、或8k字节)，或者第四指示信息不包括第二缓存的内容，但第二网络设备根据第四指示信息可确定第二缓存的内容。
如果第二网络设备支持终端设备继续使用第一缓存，则第一网络设备可向第二网络设备发送第四指示信息，而如果第二网络设备不支持终端设备继续使用第一缓存，则第一网络设备可不必向第二网络设备发送第四指示信息。
或者，S1008与S1003也可以是同一条消息，第一网络设备向第二网络设备发送第二缓存的内容，可以隐式或显示询问第二网络设备是否支持终端设备继续使用第一缓存。
S1009、第二网络设备根据第二缓存的内容更新第三缓存。
第二网络设备可用第二缓存的内容放入第三缓存中，或用第二缓存的内容替换第三缓存内原本的内容，使得第三缓存的状态与第二缓存的状态一致，也相当于使得压缩某个数据包前的第三缓存的状态与解压该数据包时的第一缓存的状态一致。
S1010、第一网络设备向第二网络设备发送K个压缩数据包，相应的，第二网络设备接收来自第一网络设备的K个压缩数据包。
在本申请实施例中，由于终端设备进行了小区切换，则第一网络设备不必对K个压缩数据包进行解压缩，而是可将K个压缩数据包通过网络设备间接口(如Xn口)转发或发送给第二网络设备，由第二网络设备对K个压缩数据包进行处理。或者，第一网络设备也可以不将K个压缩数据包发送给第二网络设备，即第一网络设备仅向第二网络设备转发解压缩成功的数据包，例如根据图7所示的实施例的介绍可知，终端设备如果从第一个未接收ACK的压缩数据包开始发送连续的N个压缩数据包，则N个压缩数据包会包括K个压缩数据包，在这种情况下，即使第一网络设备未将K个压缩数据包发送给第二网络设备，第二网络设备也可以从终端设备接收K个压缩数据包。因此，S1110是可选的步骤。
如果第一网络设备向第二网络设备发送了K个压缩数据包，那么可选的，第二网络设备接收K个压缩数据包后，可以向终端设备发送K个压缩数据包的状态报告，该状态报告指示第二网络设备已接收的压缩数据包，例如指示K个压缩数据包，或者，第二网络设备也可以不向终端设备发送该状态报告。也就是说，本申请实施例中，第一网络设备和/或第二网络设备可以向终端设备发送K个压缩数据包的状态报告。对于终端设备来说，可能会从第一网络设备接收K个压缩数据包的状态报告，或者可能会从第二网络设备接收K个压缩数据包的状态报告，或者也可能会从第一网络设备和第二网络设备都接收K个压缩数据包的状态报告。或者，本申请实施例中，第一网络设备和第二网络设备也可能都不向终端设备发送K个压缩数据包的状态报告，则终端设备就不会接收K个压缩数据包的状态报告。
另外，除了K个压缩数据包外，第一网络设备可能还从该终端设备接收了其他压缩数据包，第一网络设备已对这些压缩数据包成功解压缩，则第一网络设备可将解压缩成功的数据包也发送给第二网络设备。
S1011、终端设备向第二网络设备发送N个压缩数据包，相应的，第二网络设备接收来自终端设备的N个压缩数据包。N个压缩数据包是M个压缩数据包中的部分或全部，例如N为小于或等于M的整数。
终端设备在进行小区切换成功后，可以向第二网络设备继续发送数据包，因此终端设备对于N个压缩数据包的重传，就会重传给第二网络设备。关于S1011的更多内容，可参考图7所示的实施例中的S706。
前文介绍的是终端设备和第一网络设备不重置缓存的情况，而如果终端设备接收的第二指示信息指示不继续使用第一缓存，或者协议规定不继续使用第一缓存，则终端设备在重建PDCP层的情况下可以重置第一缓存。对于第一网络设备来说在重建PDCP层的情况 下也会重置第二缓存。在这种情况下，终端设备和第一网络设备的处理方式介绍如下。
例如，第一网络设备的PDCP层在发生重建时，已接收了压缩数据包3、4、5、7，尚未接收压缩数据包1、2、6。PDCP层接收压缩数据包3、4、5、7后，PDCP的重建指示可以触发对这些压缩数据包进行解压缩，PDCP层对压缩数据包3、4、5、7会解压缩失败，则PDCP层会丢弃压缩数据包3、4、5、7，或者，PDCP的重建指示可以触发PDCP层丢弃乱序的压缩数据包(有一种特殊情况，如果来自发送端的数据包是未经压缩的数据包，则这些数据包即使乱序，也无需丢弃)，即，不对压缩数据包3、4、5、7解压缩，而是直接丢弃压缩数据包3、4、5、7。直接丢弃乱序的压缩数据包的方案可以减少解压次数，提高处理效率，节约能耗，避免浪费资源进行无效的解压缩处理。第一网络设备只需将解压正确的数据包或未丢弃的乱序的压缩数据包发送给第二网络设备即可，无需向第二网络设备发送解压失败或未解压的压缩数据包。另外，第一网络设备的RLC层在接收压缩数据包后，会向终端设备发送ACK信息，对于已接收的压缩数据包，例如第一网络设备的RLC层会向终端设备发送ACK。
终端设备在进行小区切换完毕后，或者在PDCP层重建完毕后，可以向第二网络设备重传压缩数据包，例如终端设备从第一个未收到ACK的压缩数据包开始顺序重传。例如终端设备收到了压缩数据包0、3、4、5、7的ACK，未收到压缩数据包1、2、6的ACK，则终端设备会重传压缩数据包1～压缩数据包7。终端设备在小区切换过程中会重建PDCP层，也会重置第一缓存，则终端设备会根据重置的第一缓存重新对数据包进行压缩。终端设备之前发送给第二网络设备的压缩数据包1～压缩数据包7都是根据重置前的第一缓存对数据包1～数据包7进行压缩得到的，而此时终端设备会根据重置的第一缓存重新再次对数据包1～数据包7进行压缩，以得到压缩数据包1～压缩数据包7，终端设备再将这些压缩数据包发送给第二网络设备。可见，如果不继续使用第一缓存，则对于同一个数据包，终端设备需要进行两次压缩。
S1012、第二网络设备基于第三缓存对N个压缩数据包进行解压缩，或，第二网络设备基于第三缓存对N个压缩数据包和K个压缩数据包进行解压缩。
例如，N个压缩数据包中包括了K个压缩数据包，例如第二网络设备未从第一网络设备接收K个压缩数据包，或者虽然第二网络设备从第一网络设备接收了K个压缩数据包，但N个压缩数据包中包括K个压缩数据包，那么可理解为，第二网络设备基于第三缓存对N个压缩数据包进行解压缩。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1～压缩数据包7，则第二网络设备基于第三缓存对压缩数据包1～压缩数据包7进行解压缩。
又例如，N个压缩数据包中不包括K个压缩数据包，例如第二网络设备从第一网络设备接收了K个压缩数据包，且N个压缩数据包中不包括K个压缩数据包，那么可理解为，第二网络设备基于第三缓存对N个压缩数据包和K个压缩数据包进行解压缩。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1、2、6，则第二网络设备基于第三缓存对压缩数据包1～压缩数据包7进行解压缩，压缩数据包1～压缩数据包7就是K个压缩数据包和N个压缩数据包的并集。
通过本申请实施例提供的技术方案，可以减少终端设备的压缩次数，提升终端设备的处理效率。如果第一网络设备和/或第二网络设备向终端设备发送状态报告，还可以减少终 端设备所发送的数据量，节省传输开销。而且由于终端设备的第一缓存和第一网络设备的第二缓存均未重置，第二网络设备的第三缓存也可以根据第二缓存进行设置，则在第一网络设备和第二网络设备都不向终端设备发送状态报告的情况下，无论第二网络设备在接收K个压缩数据包后对K个压缩数据包是否进行解压缩，或者无论第二网络设备是否会接收K个压缩数据包，第二网络设备都能够获得M个压缩数据包，减少了丢包量。
图7所示的实施例和图10所示的实施例介绍的都是上行数据包的压缩过程，使用的例如为UDC技术。而本申请实施例还提供下行数据包的压缩过程，下面进行介绍。
本申请实施例提供第三种通信方法，请参见图11，为该方法的流程图，该方法涉及的是下行数据包的压缩过程。在下文的介绍过程中，以该方法应用于图3所示的网络架构为例。下文所述的终端设备例如为图3所示的网络架构中的终端设备，下文所述的第一网络设备例如为图3所示的网络架构中的网络设备。
S1101、终端设备向第一网络设备发送能力信息，相应的，第一网络设备接收来自终端设备的能力信息。该能力信息可指示支持在发生PDCP重建时继续使用第三缓存，或者指示在发生PDCP重建时不支持继续使用第三缓存；或者，该能力信息可指示支持在重建PDCP层时不重置第三缓存，或指示不支持在重建PDCP层时不重置第三缓存。第三缓存由终端设备维护，用于对数据包进行解压缩，或者说，终端设备可基于第三缓存对数据包进行解压缩，例如终端设备可采用下行压缩技术，基于第三缓存对接收的压缩数据包进行解压缩。
第一网络设备根据该能力信息就能明确终端设备是否支持继续使用第三缓存。如果终端设备支持继续使用第三缓存，第一网络设备就可以在发生切换时选择是否指示终端设备继续使用第三缓存，如果终端设备不支持继续使用第三缓存，第一网络设备就不指示终端设备继续使用第三缓存。或者，终端设备也可以不发送能力信息，第一网络设备可以根据其他因素确定是否指示终端设备继续使用第三缓存，或者终端设备是否继续使用第三缓存也可以通过协议规定，因此S1101是可选的步骤。
关于S1101的更多内容，可参考图7所示的实施例中的S701。
S1102、第一网络设备向终端设备发送M个压缩数据包，相应的，终端设备接收来自第一网络设备的K个压缩数据包。M为正整数，K为小于或等于M的正整数。K个压缩数据包可以是M个压缩数据包中的部分或全部，或者说K个压缩数据包是M个压缩数据包的子集。M个压缩数据包是第一网络设备基于第一缓存(或者，本申请实施例中的第一缓存也可称为第二缓存)对M个数据包进行压缩得到的。第一缓存由第一网络设备维护，用于第一网络设备对数据包进行压缩，例如第一网络设备可采用下行压缩技术，基于第一缓存对数据包进行压缩。
需要注意的是，第一网络设备可对压缩数据包进行相应处理后再发送。例如，第一网络设备对压缩数据包进行完整性保护以及加密处理(例如在PDCP层进行相应处理)，将处理后的压缩数据包递交给第一网络设备的底层(例如RLC层，MAC层，或物理层等)，再由第一网络设备的底层发送处理后的压缩数据包。第一网络设备发送M个压缩数据包，后文中将要涉及的第一网络设备(或，第二网络设备)发送N个压缩数据包，均可以采用类似的方式，不多赘述。
关于S1102的更多内容，可参考图7所示的实施例中的S701，在参考时，可将S701中的“终端设备”和“第一网络设备”的角色互换。
S1103、第一网络设备向终端设备发送切换命令，相应的，终端设备接收来自第一网络设备的切换命令。该切换命令可指示终端设备进行小区切换或PDCP层重建。可选的，该切换命令还可以指示在终端设备重建PDCP时继续使用第三缓存，或指示在终端设备重建PDCP时不重置第三缓存。
关于S1103的更多内容，可参考图7所示的实施例中的S703，在参考时，可将S703中终端设备维护的“第一缓存”替换为“第三缓存”，以及将第一网络设备维护的“第二缓存”替换为“第一缓存”。
S1104、终端设备重建PDCP层，且不重置第三缓存。
关于S1104的更多内容，可参考图7所示的实施例中的S704，在参考时，可将S704中终端设备维护的“第一缓存”替换为“第三缓存”。
S1105、第一网络设备重建PDCP层，且不重置第一缓存。
关于S1105的更多内容，可参考图7所示的实施例中的S705，在参考时，可将S705中第一网络设备维护的“第二缓存”替换为“第一缓存”。
S1106、第一网络设备向终端设备发送N个压缩数据包，相应的，终端设备接收来自第一网络设备的N个压缩数据包。N个压缩数据包是M个压缩数据包中的部分或全部，例如N为小于或等于M的整数。第一网络设备可从终端设备的第一个未确定成功接收的压缩数据包开始，按照压缩数据包的序号升序的顺序发送N个压缩数据包。
关于S1106的更多内容，可参考图7所示的实施例中的S706，在参考时，可将S706中的“终端设备”和“第一网络设备”的角色互换，以及将“第一缓存”和“第三缓存”的角色互换。
S1107、终端设备基于第三缓存对N个压缩数据包进行解压缩，或，终端设备基于第三缓存对N个压缩数据包和K个压缩数据包进行解压缩。
例如，N个压缩数据包中包括了K个压缩数据包，那么可理解为，终端设备基于第三缓存对N个压缩数据包进行解压缩。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1～压缩数据包7，则终端设备基于第三缓存对压缩数据包1～压缩数据包7进行解压缩。
又例如，N个压缩数据包中包括了K个压缩数据包，那么可理解为，终端设备基于第三缓存对N个压缩数据包和K个压缩数据包进行解压缩。例如M个压缩数据包为压缩数据包1～压缩数据包7，K个压缩数据包为压缩数据包3、4、5、7，N个压缩数据包为压缩数据包1、2、6，则终端设备基于第三缓存对压缩数据包1～压缩数据包7进行解压缩，压缩数据包1～压缩数据包7就是K个压缩数据包和N个压缩数据包的并集。
通过本申请实施例提供的技术方案，可以减少第一网络设备的压缩次数，提升第一网络设备的处理效率。如果终端设备向第一网络设备发送状态报告，还可以减少第一网络设备所发送的数据量，节省传输开销。而且由于终端设备的第三缓存和第一网络设备的第一缓存均未重置，在终端设备不向第一网络设备发送状态报告的情况下，无论终端设备在接收K个压缩数据包后对K个压缩数据包是否进行解压缩，终端设备都能够获得M个压缩数据包，减少了丢包量。
如果终端设备接收的第二指示信息指示不继续使用第三缓存，或者协议规定不继续使用第三缓存，则终端设备可以重置第三缓存。对于第一网络设备来说也会重置第一缓存。在这种情况下，终端设备和第一网络设备的处理方式也可参考图7所示的实施例的介绍， 在参考时，可将图7所示的实施例中的“终端设备”和“第一网络设备”的角色互换。
在本申请实施例中，可由第一网络设备指示是否继续使用第三缓存，则第一网络设备可根据具体情况相应指示是否继续使用第三缓存，例如对于能力较低的终端设备，第一网络设备可不指示继续使用第三缓存，或者可指示不继续使用第三缓存，以符合终端设备的能力需求；又例如，对于时延要求较高的场景，第一网络设备可指示继续使用第三缓存，第一网络设备只需压缩一次，节省第一网络设备的处理时间，从而减小数据包的传输时延。可见，本申请实施例的方案较为灵活。
图11所示的实施例所应用的场景是共站的场景，即，终端设备切换前和切换后接入的都是同一个网络设备。接下来介绍本申请实施例提供的第四种通信方法，该方法可应用于图4所示的网络架构，请参见图12，为该方法的流程图，该方法依然涉及的是下行压缩过程。在该方法中，终端设备在进行小区切换前接入的是第一网络设备，在进行小区切换后接入的是第二网络设备，第一网络设备和第二网络设备是不同的网络设备。下文所述的终端设备例如为图4所示的网络架构中的终端设备，下文所述的第一网络设备例如为图4所示的网络架构中的网络设备1，下文所述的第二网络设备例如为图4所示的网络架构中的网络设备2。
S1201、终端设备向第一网络设备发送能力信息，相应的，第一网络设备接收来自终端设备的能力信息。
关于S1201的更多内容，可参考图7所示的实施例中的S701。
S1202、第一网络设备向终端设备发送M个压缩数据包，相应的，终端设备接收来自第一网络设备的K个压缩数据包。M为正整数，K为小于或等于M的正整数。K个压缩数据包可以是M个压缩数据包中的部分或全部，或者说K个压缩数据包是M个压缩数据包的子集。M个压缩数据包是第一网络设备基于第一缓存对M个数据包进行压缩得到的。第一缓存由第一网络设备维护，用于第一网络设备对数据包进行压缩，例如第一网络设备可采用下行压缩技术，基于第一缓存对数据包进行压缩。
关于S1202的更多内容，可参考图7所示的实施例中的S701，在参考时，可将S701中的“终端设备”和“第一网络设备”的角色互换。
S1203、第一网络设备向第二网络设备发送第一消息，相应的，第二网络设备接收来自第一网络设备的第一消息。第一消息可用于询问是否支持终端设备继续使用第三缓存，或者，第一消息可用于询问是否支持终端设备在重建PDCP层时不重置第三缓存。其中，第三缓存为终端设备维护的用于对数据包进行解压缩的缓存，如果第三缓存发生重置，则终端设备维护的用于解压缩的第三缓存的内容为重置第三缓存后的状态，例如第三缓存会被填入预制字典。另外，第二网络设备维护第二缓存，第二缓存用于第二网络设备对数据包进行压缩，例如第二网络设备可根据第二缓存对数据包进行压缩。
第一缓存、第二缓存、第三缓存都是对应的，第一缓存由第一网络设备维护，终端设备在进行小区切换前接入的是第一网络设备，第一网络设备基于第一缓存对数据包进行压缩；第二缓存由第二网络设备维护，终端设备在进行小区切换后接入的是第二网络设备，第二网络设备可基于第二缓存对数据包进行压缩；第三缓存由终端设备维护，终端设备可基于第三缓存对来自第一网络设备和/或第二网络设备的压缩数据包进行解压缩，或者说，终端设备可根据第三缓存对基于第一缓存压缩的数据包进行解压缩，和/或，根据第三缓存对基于第二缓存压缩的数据包进行解压缩。
例如第一消息为切换请求消息，可理解为，切换请求消息包括询问信息，该询问信息可用于询问是否支持终端设备继续使用第三缓存，或询问是否支持终端设备在重建PDCP层时不重置第三缓存。或者第一消息也可以是其他消息。
S1204、第二网络设备向第一网络设备发送第二消息，相应的，第一网络设备接收来自第二网络设备的第二消息。第二消息可指示支持终端设备继续使用第三缓存，或者指示不支持终端设备继续使用第三缓存。例如第二消息为切换请求应答消息，可理解为，切换请求应答消息包括第三指示信息，第三指示信息可指示支持继续使用第三缓存，或指示不支持继续使用第三缓存。或者第二消息也可以是其他消息。
或者，第一网络设备也可以无需获知第二网络设备是否支持终端设备继续使用第三缓存，或者第一网络设备也可以通过其他方式获知第二网络设备是否支持终端设备继续使用第三缓存，因此S1203和S1204是可选的步骤。
S1205、第一网络设备向终端设备发送切换命令，相应的，终端设备接收来自第一网络设备的切换命令。该切换命令可指示终端设备进行小区切换。
关于S1205的更多内容，可参考图7所示的实施例中的S703，在参考时，可将S703中终端设备维护的“第一缓存”替换为“第三缓存”，以及将第一网络设备维护的“第二缓存”替换为“第一缓存”。
S1206、终端设备重建PDCP层，且不重置第三缓存。
关于S1206的更多内容，可参考图7所示的实施例中的S704，在参考时，可将S704中终端设备维护的“第一缓存”替换为“第三缓存”。
S1207、第一网络设备重建PDCP层，且不重置第一缓存。
关于S1207的更多内容，可参考图7所示的实施例中的S705，在参考时，可将S705中第一网络设备维护的“第二缓存”替换为“第一缓存”。
S1208、第一网络设备向第二网络设备发送第一缓存的内容，相应的，第二网络设备接收来自第一网络设备的第一缓存的内容。例如，第一网络设备可向第二网络设备发送指示信息，为了与前述的指示信息相区分，该指示信息也可称为第四指示信息，第四指示信息可指示第一缓存的内容。例如第四指示信息包括第一缓存的内容(例如根据第一缓存的大小，第一缓存的内容的大小的常见配置为2k、4k、或8k字节)，或者第四指示信息不包括第一缓存的内容，但第二网络设备根据第四指示信息可确定第一缓存的内容。
或者，S1208与S1203为同一条消息，第一网络设备向第二网络设备发送第二缓存的内容，可以隐式或显示询问第二网络设备是否支持终端设备继续使用第三缓存。
如果第二网络设备支持终端设备继续使用第三缓存，则第一网络设备可向第二网络设备发送第四指示信息，而如果第二网络设备不支持终端设备继续使用第三缓存，则第一网络设备可不必向第二网络设备发送第四指示信息，因此S1208为可选的步骤。
S1209、第二网络设备根据第一缓存的内容更新第二缓存。
第二网络设备可用第一缓存的内容替换第二缓存内原本的内容，使得第二缓存的状态与第一缓存的状态一致，也相当于使得压缩某个数据包前的第二缓存的状态与在解压缩该数据包时的第三缓存的状态一致。
S1210、第一网络设备向第二网络设备转发来自核心网设备的数据包，相应的，第二网络设备接收来自第一网络设备的数据包。例如这些数据包中包括由第一网络设备压缩过的数据包(SDU)，和/或，包括未被压缩过的数据包(SDU)。
终端设备在发生小区切换前，从第一网络设备接收到的数据包是来自核心网设备(例如UPF user plane function)的数据包。当终端设备从第一网络设备切换到第二网络设备时，后续终端设备的数据包将从核心网设备传输到第二网络设备。而在终端设备进行小区切换时，对于第一网络设备已发送但终端设备未成功接收的数据包，第一网络设备将从序号最小的未接收到来自终端设备的ACK的数据包开始，向第二网络设备进行数据包转发，即，第一网络设备将未接收到来自终端设备的ACK的数据包转发给第二网络设备。转发给第二网络设备的这部分数据包可包括第一网络设备已经压缩过的数据包，和/或，包括第一网络设备未压缩过的数据包。
其中，如果第一网络设备没有接收来自核心网的需发送给终端设备的数据包，或者第一网络设备已将来自核心网设备的需发送给该终端设备的数据包全部发送给了该终端设备，且也都接收到了来自终端设备的ACK，则无需执行S1210，因此S1210为可选的步骤。
S1211、第二网络设备向终端设备发送N个压缩数据包，相应的，终端设备接收来自第二网络设备的N个压缩数据包。N个压缩数据包是M个压缩数据包中的部分或全部，例如N为小于或等于M的整数。第二网络设备可从终端设备的第一个未确定成功接收的压缩数据包开始，按照压缩数据包的序号升序的顺序发送N个压缩数据包。
终端设备在进行小区切换成功后，第二网络设备继续向终端设备发送数据包，由于终端设备在小区切换前有未接收成功的压缩数据包，因此第二网络设备向终端设备发送N个压缩数据包。例如，第二网络设备更新第二缓存后，可根据更新的第二缓存对N个数据包进行压缩，以得到N个压缩数据包，再将N个压缩数据包发送给终端设备。N个数据包里的部分或全部数据包例如是第一网络设备发送给第二网络设备的，或者N个数据包也可能是第二网络设备从核心网设备处获得的。关于S1211的更多内容，可参考图10所示的实施例中的S1011，在参考时，可将“终端设备”和“第二网络设备”进行角色互换，另外在参考时，如果涉及到状态报告，则本申请实施例中的状态报告可以指示K个压缩数据包，该状态报告可以是终端设备发送给第一网络设备的，第一网络设备可将该状态报告发送给第二网络设备，或者，该状态报告也可以是终端设备发送给第二网络设备的。
S1212、终端设备基于第三缓存对N个压缩数据包进行解压缩，或，终端设备基于第三缓存对N个压缩数据包和K个压缩数据包进行解压缩。
关于S1212的更多内容，可参考图11所示的实施例中的S1107。
前文介绍的是终端设备和第一网络设备不重置缓存的情况，而如果终端设备接收的第二指示信息指示终端设备不继续使用第三缓存，或者协议规定终端设备不继续使用第三缓存，则终端设备可以重置第三缓存，对于第一网络设备来说也会重置第一缓存。在这种情况下，终端设备和第一网络设备的处理方式介绍如下。
例如，终端设备的PDCP层在发生重建时，已接收了压缩数据包3、4、5、7，尚未接收压缩数据包1、2、6。PDCP层接收压缩数据包3、4、5、7后，PDCP的重建指示可以触发对这些压缩数据包进行解压缩，PDCP层对压缩数据包3、4、5、7会解压缩失败，则PDCP层会丢弃压缩数据包3、4、5、7，或者，PDCP的重建指示可以触发PDCP层丢弃乱序的压缩数据包(有一种特殊情况，如果来自发送端的数据包是未经压缩的数据包，则这些数据包即使乱序，也无需丢弃)，即，不对压缩数据包3、4、5、7解压缩，而是直接丢弃压缩数据包3、4、5、7，直接丢弃乱序的压缩数据包的方案可以减少解压次数，提高处理效率，节约能耗，避免浪费资源进行无效的解压缩处理。另外，终端设备的RLC层在 接收压缩数据包后，会向第一网络设备发送ACK信息，对于已接收的压缩数据包，例如终端设备的RLC层会向第一网络设备发送ACK。
终端设备在进行小区切换完毕后，或者在PDCP层重建完毕后，第二网络设备可以向终端设备重传压缩数据包，例如第二网络设备从第一个未收到ACK的压缩数据包开始顺序重传。例如第二网络设备收到了压缩数据包0、3、4、5、7的ACK，未收到压缩数据包1、2、6的ACK，则第二网络设备会重传压缩数据包1～压缩数据包7。第二网络设备在小区切换过程中会重建PDCP层，也会重置第二缓存，则第二网络设备会根据重置的第二缓存对数据包进行压缩。第二网络设备之前发送给终端设备的压缩数据包1～压缩数据包7都是根据重置前的第二缓存对数据包1～数据包7进行压缩得到的，而此时第二网络设备会根据重置的第二缓存重新再次对数据包1～数据包7进行压缩，以得到压缩数据包1～压缩数据包7，第二网络设备再将这些压缩数据包发送给终端设备。可见，如果不继续使用第三缓存，则对于同一个数据包，第一网络设备需要进行压缩，第二网络设备还需要再次进行压缩。
通过本申请实施例提供的技术方案，可以减少网络设备的压缩次数，提升网络设备的处理效率。如果终端设备向网络设备发送状态报告，还可以减少网络设备所发送的数据量，节省传输开销。
图13给出了本申请实施例提供的一种通信装置1300的结构示意图。通信装置1300可以是图7所示的实施例、图10所示的实施例、图11所示的实施例、或图12所示的实施例中任一个实施例所述的终端设备，用于实现上述方法实施例中终端设备所执行的方法。或者，通信装置1300也可以是图7所示的实施例、图10所示的实施例、图11所示的实施例、或图12所示的实施例中任一个实施例所述的第一网络设备，用于实现上述方法实施例中对应于第一网络设备的方法。或者，通信装置1300也可以是图7所示的实施例、图10所示的实施例、图11所示的实施例、或图12所示的实施例中任一个实施例所述的第二网络设备，用于实现上述方法实施例中对应于第二网络设备的方法。具体的功能可以参见上述方法实施例中的说明。
通信装置1300包括一个或多个处理器1301。处理器1301也可以称为处理单元，可以实现一定的控制功能。所述处理器1301可以是通用处理器或者专用处理器等。例如，包括：基带处理器，中央处理器，应用处理器，调制解调处理器，图形处理器，图像信号处理器，数字信号处理器，视频编解码处理器，控制器，存储器，和/或神经网络处理器等。所述基带处理器可以用于对通信协议以及通信数据进行处理。所述中央处理器可以用于对通信装置1300进行控制，执行软件程序和/或处理数据。不同的处理器可以是独立的器件，也可以是集成在一个或多个处理器中，例如，集成在一个或多个专用集成电路上。
可选的，通信装置1300中包括一个或多个存储器1302，用以存储指令1304，所述指令1304可在所述处理器上被运行，使得通信装置1300执行上述方法实施例中描述的方法。可选的，所述存储器1302中还可以存储有数据。所述处理器和存储器可以单独设置，也可以集成在一起。
可选的，通信装置1300可以包括指令1303(有时也可以称为代码或程序)，所述指令1303可以在所述处理器上被运行，使得所述通信装置1300执行上述实施例中描述的方法。处理器1301中可以存储数据。
可选的，通信装置1300还可以包括收发器1305以及天线1306。所述收发器1305可 以称为收发单元、收发机、收发电路、收发器，输入输出接口等，用于通过天线1306实现通信装置1300的收发功能。
可选的，通信装置1300还可以包括以下一个或多个部件：无线通信模块，音频模块，外部存储器接口，内部存储器，通用串行总线(universal serial bus，USB)接口，电源管理模块，天线，扬声器，麦克风，输入输出模块，传感器模块，马达，摄像头，或显示屏等等。可以理解，在一些实施例中，通信装置1300可以包括更多或更少部件，或者某些部件集成，或者某些部件拆分。这些部件可以是硬件，软件，或者软件和硬件的组合实现。
本申请实施例中描述的处理器1301和收发器1305可实现在集成电路(integrated circuit，IC)、模拟IC、射频集成电路(radio frequency identification，RFID)、混合信号IC、专用集成电路(application specific integrated circuit，ASIC)、印刷电路板(printed circuit board，PCB)、或电子设备等上。实现本文描述的通信装置，可以是独立设备(例如，独立的集成电路，手机等)，或者可以是较大设备中的一部分(例如,可嵌入在其他设备内的模块)，具体可以参照前述关于终端设备，以及网络设备的说明，在此不再赘述。
本申请实施例提供了一种终端设备，该终端设备(为描述方便，称为UE)可用于前述各个实施例中。所述终端设备包括用以实现图7、图10、图11或图12中的任意一个或多个附图所示的实施例中所述的终端设备功能的相应的手段(means)、单元和/或电路。例如，终端设备，包括收发模块，用以支持终端设备实现收发功能，和，处理模块，用以支持终端设备对信号进行处理。
图14给出了本申请实施例提供的一种终端设备的结构示意图。
该终端设备1400可适用于图3或图4所示的架构中。为了便于说明，图14仅示出了终端设备1400的主要部件。如图14所示，终端设备1400包括处理器、存储器、控制电路、天线以及输入输出装置。处理器主要用于对通信协议以及通信数据进行处理，以及对整个终端设备1400进行控制，执行软件程序，处理软件程序的数据。存储器主要用于存储软件程序和数据。控制电路主要用于基带信号与射频信号的转换以及对射频信号的处理。天线主要用于收发电磁波形式的射频信号。输入输出装置，例如触摸屏，显示屏，麦克风，键盘等主要用于接收用户输入的数据以及对用户输出数据。
以终端设备1400是手机为例，当终端设备1400开机后，处理器可以读取存储单元中的软件程序，解释并执行软件程序的指令，处理软件程序的数据。当需要通过无线发送数据时，处理器对待发送的数据进行基带处理后，输出基带信号至控制电路，控制电路将基带信号进行射频处理后将射频信号通过天线以电磁波的形式向外发送。当有数据发送到终端设备1400时，控制电路通过天线接收到射频信号，将射频信号转换为基带信号，并将基带信号输出至处理器，处理器将基带信号转换为数据并对该数据进行处理。
本领域技术人员可以理解，为了便于说明，图14仅示出了一个存储器和处理器。在一些实施例中，终端设备1400可以包括多个处理器和存储器。存储器也可以称为存储介质或者存储设备等，本发明实施例对此不做限制。
作为一种可选的实现方式，处理器可以包括基带处理器和中央处理器，基带处理器主要用于对通信协议以及通信数据进行处理，中央处理器主要用于对整个终端设备1400进行控制，执行软件程序，处理软件程序的数据。图14中的处理器集成了基带处理器和中央处理器的功能，本领域技术人员可以理解，基带处理器和中央处理器也可以是各自独立 的处理器，通过总线等技术互联。终端设备1400可以包括多个基带处理器以适应不同的网络制式，终端设备1400可以包括多个中央处理器以增强其处理能力，终端设备1400的各个部件可以通过各种总线连接。所述基带处理器也可以表述为基带处理电路或者基带处理芯片。所述中央处理器也可以表述为中央处理电路或者中央处理芯片。对通信协议以及通信数据进行处理的功能可以内置在处理器中，也可以以软件程序的形式存储在存储单元中，由处理器执行软件程序以实现基带处理功能。
在一个例子中，可以将具有收发功能的天线和控制电路视为终端设备1400的收发单元1410，将具有处理功能的处理器视为终端设备1400的处理单元1420。如图14所示，终端设备1400包括收发单元1410和处理单元1420。收发单元也可以称为收发器、收发机、收发装置等。可选的，可以将收发单元1410中用于实现接收功能的器件视为接收单元，将收发单元1410中用于实现发送功能的器件视为发送单元，即收发单元1410包括接收单元和发送单元。示例性的，接收单元也可以称为接收机、接收器、接收电路等，发送单元可以称为发射机、发射器或者发射电路等。
本申请实施例还提供了一种网络设备，该网络设备可用于前述各个实施例中。所述网络设备包括用以实现图7、图10、图11或图12中的任意一个或多个附图所示的实施例中所述的例如第一网络设备的功能的手段(means)、单元和/或电路。或者，所述网络设备包括用以实现图7、图10、图11或图12中的任意一个或多个附图所示的实施例中所述的例如第二网络设备的功能的手段(means)、单元和/或电路。例如，网络设备包括收发模块，用以支持网络设备实现收发功能，和，处理模块，用以支持网络设备对信号进行处理。
图15给出了本申请实施例提供的一种网络设备的结构示意图。如图15所示，网络设备可适用于3或图4所示的架构中。该网络设备包括：基带装置1501，射频装置1502、天线1503。在上行方向上，射频装置1502通过天线1503接收终端设备发送的信息，将终端设备发送的信息发送给基带装置1501进行处理。在下行方向上，基带装置1501对终端设备的信息进行处理，并发送给射频装置1502，射频装置1502对终端设备的信息进行处理后经过天线1503发送给终端设备。
基带装置1501包括一个或多个处理单元15011，存储单元15012和接口15013。其中处理单元15011用于支持网络设备执行上述方法实施例中网络设备的功能。存储单元15012用于存储软件程序和/或数据。接口15013用于与射频装置1502交互信息，该接口包括接口电路，用于信息的输入和输出。在一种实现中，所述处理单元为集成电路，例如一个或多个ASIC，或，一个或多个DSP，或，一个或者多个FPGA，或者这些类集成电路的组合。这些集成电路可以集成在一起，构成芯片。存储单元15012与处理单元15011可以位于同一个芯片中，即片内存储元件。或者存储单元15012也可以与处理单元15011处于不同芯片上，即片外存储元件。所述存储单元15012可以是一个存储器，也可以是多个存储器或存储元件的统称。
网络设备可以通过一个或多个处理单元调度程序的形式实现上述方法实施例中的部分或全部步骤。例如实现图7、图10、图11或图12中的任意一个或多个附图所示的实施例中第一网络设备和/或第二网络设备的相应的功能。所述一个或多个处理单元可以支持同一种制式的无线接入技术，也可以支持不同种制式的无线接入制式。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件 还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的计算机可读存储介质，可以是计算机能够存取的任何可用介质。以此为例但不限于：计算机可读介质可以包括随机存取存储器(random access memory，RAM)、只读存储器(read-only memory，ROM)、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦可编程只读存储器(electrically erasable programmable read only memory，EEPROM)、紧凑型光盘只读存储器(compact disc read-only memory，CD-ROM)、通用串行总线闪存盘(universal serial bus flash disk)、移动硬盘、或其他光盘存储、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质。另外，通过示例性但不是限制性说明，许多形式的RAM可用，例如静态随机存取存储器(static RAM，SRAM)、动态随机存取存储器(dynamic RAM，DRAM)、同步动态随机存取存储器(synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(double data rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(synchlink DRAM，SLDRAM)或直接内存总线随机存取存储器(direct rambus RAM，DR RAM)。
以上所述，仅为本申请的具体实施方式，但本申请实施例的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请实施例揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请实施例的保护范围之内。因此，本申请实施例的保护范围应所述以权利要求的保护范围为准。

Claims (24)

  1. 一种通信方法，应用于终端设备，其特征在于，
    发送M个压缩数据包，所述M个压缩数据包是基于第一缓存对M个数据包压缩得到的，M为正整数；
    重建PDCP层，且不重置所述第一缓存；
    发送N个压缩数据包，所述N个压缩数据包是所述M个压缩数据包中的部分或全部，N为小于或等于M的正整数。
  2. 根据权利要求1所述的方法，其特征在于，所述N个压缩数据包中序号最小的数据包是网络设备未成功接收的数据包中序号最小的数据包。
  3. 根据权利要求1或2所述的方法，其特征在于，所述方法还包括：
    发送能力信息，所述能力信息用于指示支持继续使用所述第一缓存。
  4. 根据权利要求1～3任一项所述的方法，其特征在于，所述方法还包括：
    接收切换命令，所述切换命令用于指示小区切换或重建PDCP层，还用于指示继续使用所述第一缓存。
  5. 根据权利要求1～4任一项所述的方法，其特征在于，
    发送M个压缩数据包，包括：向第一网络设备发送所述M个压缩数据包；
    发送N个压缩数据包，包括：向所述第一网络设备发送所述N个压缩数据包。
  6. 根据权利要求1～4任一项所述的方法，其特征在于，
    发送M个压缩数据包，包括：向第一网络设备发送所述M个压缩数据包，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；
    发送N个压缩数据包，包括：向第二网络设备发送所述N个压缩数据包，所述第一网络设备是所述终端设备进行小区切换后接入的网络设备。
  7. 一种通信方法，应用于第一网络设备，其特征在于，包括：
    从终端设备接收K个压缩数据包，所述K个压缩数据包是基于第一缓存对K个数据包压缩得到的，K为正整数；
    重建PDCP层，且不重置第二缓存，所述第二缓存用于所述第一网络设备对基于所述第一缓存压缩的数据包进行解压缩。
  8. 根据权利要求7所述的方法，其特征在于，所述方法还包括：
    向第二网络设备发送所述K个压缩数据包，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备。
  9. 根据权利要求7或8所述的方法，其特征在于，所述方法还包括：
    向第二网络设备发送指示信息，所述指示信息用于指示所述第二缓存的内容，所述第二缓存的内容用于更新第三缓存，所述第三缓存用于所述第二网络设备对基于所述第一缓存压缩的数据包进行解压缩，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备。
  10. 根据权利要求7～9任一项所述的方法，其特征在于，所述方法还包括：
    向所述第二网络设备发送第一消息，所述第一消息用于询问是否支持所述终端设备继续使用第一缓存，所述第二网络设备是所述终端设备进行小区切换后接入的网络设备，所 述第一网络设备是所述终端设备进行小区切换前接入的网络设备；
    所述第一网络设备从所述第二网络设备接收第二消息，所述第二消息用于指示支持所述终端设备继续使用所述第一缓存。
  11. 根据权利要求7所述的方法，其特征在于，所述方法还包括：
    向所述终端设备发送状态报告，所述状态报告用于指示所述第一网络设备已接收所述K个压缩数据包。
  12. 根据权利要求11所述的方法，其特征在于，所述方法还包括：
    从所述终端设备接收N个压缩数据包，所述N个压缩数据包是M个压缩数据包的中的部分或全部，所述K个压缩数据包是所述M个压缩数据包的中的部分或全部，所述M个数据包的序号连续，且所述M个压缩数据包是基于所述第一缓存对M个数据包压缩得到的，M为正整数，N为小于或等于M的正整数，且K为小于或等于M的正整数。
  13. 根据权利要求11或12所述的方法，其特征在于，所述N个压缩数据包中序号最小的数据包是所述第一网络设备未成功接收的数据包中序号最小的数据包。
  14. 根据权利要求7～13任一项所述的方法，其特征在于，所述方法还包括：
    从所述终端设备接收能力信息，所述能力信息用于指示所述终端设备支持继续使用所述第一缓存。
  15. 根据权利要求7～14任一项所述的方法，其特征在于，所述方法还包括：
    向所述终端设备发送切换命令，所述切换命令用于指示小区切换或重建PDCP层，还用于指示继续使用所述第一缓存。
  16. 一种通信方法，应用于第二网络设备，其特征在于，包括：
    从第一网络设备接收K个压缩数据包，所述K个压缩数据包是基于第一缓存对K个数据包压缩得到的，所述第二网络设备是终端设备进行小区切换后接入的网络设备，所述第一网络设备是所述终端设备进行小区切换前接入的网络设备；
    从所述第一网络设备接收指示信息，所述指示信息用于指示第二缓存的内容，所述第二缓存用于所述第一网络设备对基于所述第一缓存压缩的数据包进行解压缩；
    根据所述第二缓存的内容更新第三缓存，所述第三缓存用于所述第二网络设备对基于所述第一缓存压缩的数据包进行解压缩。
  17. 根据权利要求16所述的方法，其特征在于，所述方法还包括：
    从所述第一网络设备接收第一消息，所述第一消息用于询问是否支持所述终端设备继续使用第一缓存；
    向所述第一网络设备发送第二消息，所述第二消息用于指示支持所述终端设备继续使用所述第一缓存。
  18. 根据权利要求16或17所述的方法，其特征在于，所述方法还包括：
    向所述终端设备发送状态报告，所述状态报告用于指示所述第二网络设备已接收所述K个压缩数据包。
  19. 根据权利要求16～18任一项所述的方法，其特征在于，所述N个压缩数据包中序号最小的数据包是所述第二网络设备未成功接收的数据包中序号最小的数据包。
  20. 根据权利要求16～19任一项所述的方法，其特征在于，所述第一缓存对应于第一无线承载，所述第一无线承载包括所述终端设备的部分或全部无线承载。
  21. 一种终端设备，其特征在于，包括：
    一个或多个处理器；
    一个或多个存储器；
    以及一个或多个计算机程序，其中所述一个或多个计算机程序被存储在所述一个或多个存储器中，所述一个或多个计算机程序包括指令，当所述指令被所述终端设备的一个或多个处理器执行时，使得所述终端设备执行如权利要求1～6中任一项所述的方法。
  22. 一种网络设备，其特征在于，包括：
    一个或多个处理器；
    一个或多个存储器；
    以及一个或多个计算机程序，其中所述一个或多个计算机程序被存储在所述一个或多个存储器中，所述一个或多个计算机程序包括指令，当所述指令被所述网络设备的一个或多个处理器执行时，使得所述网络设备执行如权利要求7～15中任一项所述的方法，或使得所述网络设备执行如权利要求16～20中任一项所述的方法。
  23. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质用于存储计算机程序，当所述计算机程序在计算机上运行时，使得所述计算机执行如权利要求1～6中任一项所述的方法，或者使得所述计算机执行如权利要求7～15中任一项所述的方法，或者使得所述计算机执行如权利要求16～20中任一项所述的方法。
  24. 一种芯片，其特征在于，包括一个或多个处理器和通信接口，所述一个或多个处理器用于读取指令，以执行权利要求1～6中任一项所述的方法，或者执行权利要求7～15中任一项所述的方法，或者执行权利要求16～20中任一项所述的方法。
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