WO2014094613A1

WO2014094613A1 - Data transmission method and device, and communication system

Info

Publication number: WO2014094613A1
Application number: PCT/CN2013/089763
Authority: WO
Inventors: 刘菁; 衡鹏
Original assignee: 华为技术有限公司
Priority date: 2012-12-21
Filing date: 2013-12-18
Publication date: 2014-06-26
Also published as: CN107911201A; CN103888215A; CN103888215B; CN107911201B

Abstract

The present invention relates to the technical field of communications, and disclosed is a data transmission method. The method comprises the steps of: a source evolved Node B sending a sequence number (SN) state transmission message to a target evolved Node B, the SN state transmission message containing SN information corresponding to a protocol data unit (PDU) packet of the packet data convergence protocol (PDCP) used for indicating that the source evolved Node B has not received the acknowledgement (ACK) feedback. Also provided are a device for data transmission and a communication system. By means of the present invention, by containing the sequence number information corresponding to the PDU packet of the PDCP used for indicating that the source evolved Node B has not received the acknowledgement in the sequence number state transmission message sent by the source evolved Node B, after the source eNB forwards data, it can be guaranteed that an SDU packet of the PDCP already allocated with a sequence number on the source eNB also can be allocated with the same sequence number on the target eNB, thereby guaranteeing the continuity of the SDU packet of the PDCP.

Description

The present invention claims the priority of a Chinese patent application filed on December 21, 2012 by the Chinese Patent Office, the application number is 201210563440.9, and the invention is entitled "data transmission method, device and communication system". The entire contents of this application are incorporated herein by reference.

The present invention relates to the field of wireless communication technologies, and in particular, to a data transmission method, apparatus, and communication system. The switching process between Evolved Node Bs (eNBs) in the Long Term Evolution (LTE) system is shown in FIG. 1 . In the process of FIG. 1, in the Unacknowledged Mode (UM) mode, when the user equipment (User Equipment, UE) switches from the source eNB to the target eNB, the IP packet buffered by the source eNB can be forwarded to the target through the X2 interface. The eNB may not be forwarded to the target eNB, and the target eNB restarts the data of the buffer data in the Packet Data Convergence Protocol (PDCP) layer from the PDCP sequence number (SN)=0. . In the Acknowledged Mode (AM) mode, in order to ensure the continuity of data packets during the handover process, two types of data need to be forwarded on the communication interface (X2) between the eNode Bs, one without passing through the PDCP layer. The processed IP packet, that is, the PDCP Service Data Unit (SDU) packet, and the second is the PDCP Protocol Data Unit (PDU) packet that does not receive the Acknowledgement (ACK) feedback. The ACK is fed back by the user equipment when it is uplink, and is fed back by the base station when it is downlink.

A Relay architecture (referred to as ALT-4) is proposed in 3GPP TR 36.806. The protocol stack of the control plane and user plane of ALT-4 is shown in Figure 2 and Figure 3. For the user plane of the ALT-4 architecture, the data of the communication interface (Un) of the relay node and the eNB does not need to perform IP, User Datagram Protocol (UDP), General Packet Radio Service Tunneling Protocol-User plane. Layer processing, It only needs to be processed to the PDCP layer, thereby shortening the processing delay of data transmission. However, when ALT-4 is used, the target eNB cannot discern which packets received from the X2 interface are PDCP SDUs that have not been processed by the PDCP layer due to data transfer without the Transport Net Layer (TLL). Packet, which data is the PDCP PDU packet processed by the PDCP layer that has not received the ACK feedback, which may cause the out-of-order of the forwarding data when the target eNB performs SN association. SUMMARY OF THE INVENTION Embodiments of the present invention provide a data transmission method, apparatus, and communication system, so that after data forwarding by a source eNB, it can be ensured that a PDCP SDU packet to which a source eNB has been assigned a sequence number SN can be allocated the same on the target eNB. SN, thus ensuring the continuity of the PDCP SDU package.

In order to solve the above technical problem, the embodiment of the present invention discloses the following technical solutions: In a first aspect, a data transmission method is provided, where the method includes the following steps: The source base station sends a sequence number SN status transmission message to a target base station, where the SN status The transport message includes SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet indicating that the source base station does not receive the acknowledgement character ACK feedback.

In a first possible implementation manner of the first aspect, the SN status transmission message is a PDCP PDU packet that the source base station does not receive the ACK feedback, and the SN information is a field PDCP PDU number

The PDCP PDU packet further includes a field F for indicating whether it is necessary to transmit the SN information corresponding to the PDCP PDU packet that has not received the ACK feedback.

The PDCP PDU packet further includes a field for counting PDCP PDU packets for which the source base station does not receive ACK feedback.

In a second possible implementation manner of the first aspect, the SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes SN information corresponding to a PDCP PDU packet that the source base station does not receive ACK feedback. .

The method further includes the steps of: performing data forwarding in the source base station in the following order: Forwarding the PDCP PDU packet that did not receive the ACK feedback to the target base station, and then

The PDCP Service Data Unit SDU packet is forwarded to the target base station.

The method is applied to a relay architecture as defined by the 3GPP TR 36.806 protocol.

The second aspect provides a data transmission method, where the method includes the following steps: the target base station receives a sequence number SN status transmission message from the source base station, where the SN status transmission message includes, to indicate that the source base station does not receive the confirmation character. SN information corresponding to the ACK feedback packet data convergence protocol PDCP protocol data unit PDU packet;

The target base station allocates a sequence number to the received PDCP service data unit SDU packet according to the SN information.

In a first possible implementation manner of the second aspect, the SN information is a field PDCP PDU number

In a second possible implementation manner of the second aspect, the SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes SN information corresponding to a PDCP PDU packet that the source base station does not receive ACK feedback. .

Before the target base station allocates a sequence number to the received PDCP SDU packet according to the SN information, the method further includes: the target base station performs PDCP layer processing on the data forwarded by the source base station according to the following sequence: The PDCP PDU packet forwarded by the source base station without receiving the ACK feedback, and then processing the PDCP SDU packet forwarded by the source base station.

The third aspect provides an apparatus for data transmission, where the apparatus includes: a sending unit, configured to send an SN status transmission message, where the SN status transmission message includes, to indicate that the source base station does not receive the acknowledgement character ACK The SN information corresponding to the fed back packet data convergence protocol PDCP protocol data unit PDU packet.

In a first possible implementation manner of the third aspect, the SN state transmission message is a source base The station does not receive the PDCP PDU packet of the ACK feedback, and the SN information is the field PDCP PDU number; or

The SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes SN information corresponding to the PDCP PDU packet that the source base station does not receive the ACK feedback.

In a second possible implementation manner of the third aspect, the apparatus further includes a forwarding unit, where the forwarding unit is configured to perform data forwarding according to the following sequence: first forwarding a PDCP PDU packet that does not receive the ACK feedback to the The target base station then forwards the PDCP Service Data Unit SDU packet to the target base station.

The fourth aspect provides an apparatus for data transmission, where the apparatus includes: a receiving unit, configured to receive an SN status transmission message sent by a source base station, where the SN status transmission message includes a data unit PDU packet SN information;

And an allocating unit, configured to allocate a sequence number to the received PDCP service data unit SDU packet according to the SN information.

In a first possible implementation manner of the fourth aspect, the SN status transmission message is a PDCP PDU packet that the source base station does not receive the ACK feedback, and the SN information is a field PDCP PDU number; or

In a second possible implementation manner of the fourth aspect, the apparatus further includes: a processing unit, configured, by the allocation unit, before, after, or after the sequence number is received for the received PDCP service data unit SDU packet according to the SN information Performing PDCP layer processing on the data forwarded by the source base station according to the following sequence: first processing the PDCP PDU packet forwarded by the source base station without receiving the ACK feedback, and then processing the PDCP SDU packet forwarded by the source base station. A fifth aspect, a communication system for data transmission, the communication system comprising the apparatus of any one of the foregoing possible implementations of the third aspect, and the apparatus of any one of the possible implementations of the fourth aspect .

According to a sixth aspect, a system for data transmission is provided, where the system includes: The port is configured to send an SN state transmission message, where the SN state transmission message includes SN information corresponding to a packet data convergence protocol PDCP protocol data unit PDU packet indicating that the source base station does not receive the acknowledgement character ACK feedback.

In a first possible implementation manner of the sixth aspect, the SN status transmission message is a PDCP PDU packet that the source base station does not receive the ACK feedback, and the SN information is a field PDCP PDU number; or

In a second possible implementation manner of the sixth aspect, the system further includes a processor, where the processor is configured to perform data forwarding according to the following sequence: first forwarding a PDCP PDU packet that does not receive ACK feedback to the target The base station then forwards the PDCP Service Data Unit SDU packet to the target base station. The seventh aspect provides a system for data transmission, where the system includes: a network interface, configured to receive an SN state transmission message sent by a source base station, where the SN state transmission message encapsulates a data unit PDU packet corresponding to The SN information is used by the controller to allocate a sequence number to the received PDCP service data unit SDU packet according to the SN information.

In a first possible implementation manner of the seventh aspect, the SN status transmission message is a PDCP PDU packet that the source base station does not receive the ACK feedback, and the SN information is a field PDCP PDU number; or

The SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes SN information corresponding to the PDCP PDU packet that the source base station does not receive the ACK feedback. The system further includes a processor, configured to perform PDCP on the data forwarded by the source base station in the following order before or after the sequence number is assigned to the received PDCP service data unit SDU packet according to the SN information. Layer processing: first processing the PDCP PDU packet forwarded by the source base station without receiving ACK feedback, and then processing the PDCP SDU forwarded by the source base station package.

The foregoing technical solution has the following advantages: the present invention includes, by using the sequence number SN status transmission message sent by the source base station, the SN information corresponding to the source base station not receiving the acknowledgement PDCP PDU packet, so that after the source eNB performs data forwarding It can be ensured that the PDCP SDU packets with the sequence number SN already allocated by the source eNB can also be allocated to the same SN on the target eNB, thereby ensuring the continuity of the PDCP SDU packets.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a flowchart of handover between eNBs in an existing LTE system;

Figure 2 is the ALT-4 control plane protocol stack;

Figure 3 is the ALT-4 username protocol stack;

4 is a schematic diagram of a format of a conventional PDCP PDU packet;

Figure 5 is a schematic diagram showing the format of a PDCP PDU packet used in an embodiment of the method of the present invention;

Figure 6 is a block diagram of one embodiment of an apparatus for data transmission of the present invention;

Figure 7 is a block diagram of another embodiment of an apparatus for data transmission of the present invention;

Figure 8 is a block diagram of an embodiment of a communication system of the present invention;

Figure 9 is a block diagram of one embodiment of a system for data transmission of the present invention;

Figure 10 is a block diagram of another embodiment of a system for data transmission of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, specific embodiments of the present invention will be described in further detail with reference to the accompanying drawings and embodiments. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

First, an LTE system using the ALT-4 architecture is taken as an example to describe a handover method between eNBs in an existing LTE system, and a flowchart thereof is shown in FIG. 1. In FIG. 1, UE represents a user equipment, MME represents a mobility management entity, SGW represents a serving gateway, and MME and SGW are involved in the entire handover process. The network entity to. The entire switching process includes 18 steps, including a control plane process and a user plane process. The control plane switching process includes a handover preparation process, a handover execution process, and a handover completion process, and the user plane process includes data forwarding.

As shown in FIG. 1, the data transmission method of the present invention is mainly modified for the sequence number SN status transmission message transmitted in step 8 such that after the UE confirms that the handover is successful (step 11), the target base station (this implementation) In the example, the eNB) does not appear out of order when receiving data from the source base station (eNB in this embodiment).

An embodiment of the first data transmission method of the present invention describes a process of data transmission in step 8 of FIG. 1 from a source base station side, the method comprising the steps of: the source base station transmitting a sequence number SN status transmission message to a target base station, the SN status transmission The message includes SN information corresponding to the PDCP PDU packet (the PDCP PDU packet refers to the data packet processed by the PDCP layer) that the source base station does not receive the acknowledgment character ACK feedback. The SN status transmission message is a PDCP PDU packet that the source base station does not receive the ACK feedback, and the SN information is a field PDCP PDU number „

Since the data is transmitted between the source eNB and the target base station through the relay node (RN) under the ALT-4 architecture, there is no GTP (GPRS Tunneling Protocol) layer between the RN and the target eNB, and only the PDCP layer. In order for the target eNB to know which of the RN retransmission data packets are PDCP PDU packets that the source base station has not received the ACK feedback, which are the PDCP PDU data packets that the source base station has received the ACK feedback, need to be in the existing PDCP PDU packet format. A field is added to indicate that the source base station does not receive the SN information corresponding to the PDCP PDU packet of the ACK feedback.

The original PDCP PDU packet format is shown in Figure 4. D/C indicates whether the PDCP PDU packet is a data plane packet or a control plane packet, R is a reserved field, and the PDCP SN is a PDCP PDU packet passing through an interface between the RN and the target eNB. When the Un port is transmitted, the sequence number generated by the PDCP layer on the Un port is used to ensure the correctness of the serial number of the PDCP PDU packet transmitted by the Un interface. The PDCP SN ( cont. ) is the count value of the transmitted PDCP PDU packet, Data and The ellipsis is the PDCP PDU packet data portion, and Oct is the octal.

The format of the modified PDCP PDU packet is as shown in Figure 5, where the original reserved field R is modified to be the F field: 1 bit, used to indicate whether the PDCP PDU that the source base station has not received ACK feedback on the Un interface needs to be delivered. The SN information corresponding to the packet. That is: when the F field is 0, it means that no source is needed. The SN information corresponding to the PDCP PDU packet that the base station has not received the ACK feedback on the Un interface; the value of 1 indicates that the SN information corresponding to the PDCP PDU packet that the source base station has not received the ACK feedback on the Un interface needs to be transmitted; the newly added PDCP PDU number Field: 12 bits, indicating the SN information corresponding to the PDCP PDU packet that the source base station has not received the ACK feedback. In Figure 5, the newly added PDCP PDU number ( cont. ) is used to count the PDCP PDU packet value for which the source base station does not receive ACK feedback, and the ellipsis indicates data. In this case, when F=l, the 12-bit PDCP DPU number can be read to obtain the sequence number of the PDCP PDU packet that the source base station does not receive the ACK feedback, because the PDCP PDU packet is not received. The priority is higher than the PDCP SDU packet. Therefore, the sequence number in the PDCP PDU packet received first can be assigned to the sequence number of the PDCP SDU packet received later, thereby ensuring the continuity of the PDCP SDU packet.

For example: The source node wants to send packets 1, 2, 3, 4, 5, where packets 4, 5 are PDCP SDU packets, and after sending packets 1, 2, 3, receive ACK feedback for PDCP PDU packets 1, 2 , but did not receive ACK feedback from PDCP PDU packet 3. At this time, the source node needs to resend the data packets 3, 4, and 5 to the target node in the order of data packets 3, 4, 5, or 3, 5, 4, because the PDCP PDU packet indicates that the SN=3 of the PDCP PDU packet is After receiving the PDCP PDU packet, the target node assigns sequence numbers 4 and 5 to the PDCP SDU packets in the order of the received PDCP SDU packets, thereby ensuring the continuity of the PDCP SDU packets.

The embodiment of the second data transmission method of the present invention describes the process of data transmission in step 8 of FIG. 1 from the target base station side, the method comprising the steps of: the target base station receiving a sequence number SN status transmission message from the source base station, the SN status The transport message includes SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet indicating that the source base station does not receive the acknowledgement character ACK feedback;

After the introduction of the ALT-4 trunking architecture, the PDCP SDU packet transmitted on the Un interface cannot carry the SN information corresponding to the PDCP SDU packet. Therefore, the PDCP SN transmitted on the downlink X2 interface after the ALT-4 relay architecture is introduced. Status report changed to include PDCP that has not received ACK feedback SN information corresponding to the PDU packet. The PDCP SDU packet is not processed by the PDCP layer. The sequence number is not assigned. The sequence number is allocated at the target base station, and its priority is the lowest when transmitting. The PDCP layer has not received the ACK feedback. The PDCP PDU packet has a higher priority. Therefore, the data forwarding mechanism of the source base station is: the source base station first forwards the PDCP PDU packet that has not received the ACK feedback, and then forwards the data to the PDCP SDU packet, because the Un interface is used. The AM mode is also adopted, so the target base station can receive the data forwarded by the source base station in order. Then, the target base station uses the SN information transmitted in the PDCP SN status report to ensure that the PDCP SDU packet with the sequence number already allocated on the source base station can be allocated the same sequence number on the target base station, thereby ensuring the continuity of the PDCP SDU packet. The PDCP layer data on the Un interface can also be processed in sequence for the PDCP SDU data that is forwarded.

For example: The source node wants to send packets 1, 2, 3, 4, 5, where packets 4, 5 are PDCP SDU packets, and after sending packets 1, 2, 3, receive ACK feedback for PDCP PDU packets 1, 2 , but did not receive ACK feedback from PDCP PDU packet 3. At this time, the source node needs to resend the data packets 3, 4, and 5 to the target node in the order of data packets 3, 4, 5, or 3, 5, 4, because the PDCP SN status report indicates that the SN=3 of the PDCP PDU packet is specified. After receiving the PDCP PDU packet, the target node assigns sequence numbers 4 and 5 to the PDCP SDU packet according to the received PDCP SDU packet, thereby ensuring the continuity of the PDCP SDU packet.

The data transmission method of the present invention is applicable to a relay architecture defined by the 3GPP TR 36.806 protocol. Corresponding to the embodiment of the data transmission method of the present invention, the present invention also provides an embodiment of an apparatus, a communication system for data transmission.

Referring to Figure 6, there is shown a block diagram of one embodiment of an apparatus for data transmission of the present invention, which describes the process of data transmission from the source base station side.

The device includes: a sending unit 610, configured to send an SN status transmission message, where the SN status transmission message includes SN information corresponding to a PDCP PDU packet indicating that the source base station does not receive the ACK feedback;

The forwarding unit 620 is configured to perform data forwarding in the following sequence: The PDCP PDU packet that has not received the ACK feedback is forwarded to the target base station, and then the PDCP service data unit SDU packet is forwarded to the target base station.

As an implementation manner, the SN status transmission message is a PDCP PDU packet that the source base station does not receive the ACK feedback, and the SN information is a field PDCP PDU number.

As another implementation manner, the SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes SN information corresponding to the PDCP PDU packet that the source base station does not receive the ACK feedback.

Referring to Figure 7, there is shown a block diagram of another embodiment of an apparatus for data transmission of the present invention, which describes a process of data transmission from a target base station side.

The device includes: a receiving unit 710, configured to receive an SN state transmission message sent by the source base station, where the SN state transmission message includes SN information corresponding to a PDCP PDU packet indicating that the source base station does not receive the acknowledgement character ACK feedback;

The allocating unit 720 is configured to allocate a sequence number to the received PDCP service data unit SDU packet according to the SN information.

The processing unit 730 is configured to perform, by the allocation unit 720, PDCP layer processing on the data forwarded by the source base station before or after the sequence number is received for the received PDCP service data unit SDU packet according to the SN information: First, the PDCP PDU packet that is not received by the source base station and does not receive the ACK feedback is processed, and then the PDCP SDU packet forwarded by the source base station is processed.

Referring to Figure 8, a block diagram of one embodiment of a communication system for data transmission of the present invention is shown. The communication system comprises: any of the embodiments of the apparatus 810 for data transmission described above from the source base station side, and any embodiment of the apparatus 820 for data transmission described from the target base station side, eg, the communication The system can be an LTE system. Referring to Figure 9, a block diagram of one embodiment of a system for data transmission of the present invention is shown.

The system includes: a system for data transmission, the system includes: a network interface 910, configured to send an SN status transmission message, where the SN status transmission message includes, to indicate that the source base station does not receive the ACK feedback. SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet;

The processor 920 is configured to perform data forwarding according to the following sequence: first, forward a PDCP PDU packet that does not receive ACK feedback to the target base station, and then forward the PDCP service data unit SDU packet to the target. Base station.

Referring to Figure 10, a block diagram of another embodiment of a system for data transmission of the present invention is shown. The system includes: a network interface 1010, configured to receive an SN status transmission message sent by a source base station, where the SN status transmission message includes a ACK controller 1020 for indicating that the source base station does not receive an acknowledgement character, according to the SN Information, assigning a sequence number to the received PDCP service data unit SDU packet;

The processor 1030 is configured to perform PDCP layer processing on the data forwarded by the source base station in the following sequence before or after the controller 1020 allocates a sequence number to the received PDCP service data unit SDU packet according to the SN information: First, the PDCP PDU packet that is not received by the source base station and does not receive the ACK feedback is processed, and then the PDCP SDU packet forwarded by the source base station is processed.

In another implementation manner, the SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes a PDCP PDU packet that the source base station does not receive ACK feedback. Corresponding SN information.

As can be seen from the above embodiment, the present invention includes, by using the sequence number SN status transmission message sent by the source base station, SN information indicating that the source base station does not receive the acknowledge PDCP PDU packet, so that the data is forwarded at the source eNB. After that, it can be ensured that the PDCP SDU packets whose sequence number SN has been allocated by the source eNB can also be allocated to the same SN on the target eNB, thereby ensuring the continuity of the PDCP SDU packet.

Those skilled in the art will appreciate that various aspects of the invention, or possible implementations of various aspects, may be embodied as a system, method, or computer program product. Thus, aspects of the invention, or possible implementations of various aspects, may be in the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, etc.), or a combination of software and hardware aspects, They are collectively referred to herein as "circuits," "modules," or "systems." Furthermore, various aspects of the invention, or possible implementations of various aspects, may take the form of a computer program product, which is a computer readable program code stored on a computer readable medium.

The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium includes, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing, such as random access memory (RAM), read only memory (ROM), Erase programmable read-only memory (EPROM or flash memory), optical fiber, portable read-only memory (CD-ROM).

The processor in the computer reads the computer readable program code stored in the computer readable medium, such that the processor can perform the functional actions specified in each step or combination of steps in the flowchart; A device that functions as specified in each block, or combination of blocks.

The computer readable program code can be executed entirely on the user's computer, partly on the user's computer, as a separate software package, partly on the user's computer and partly on the remote computer, or entirely on the remote computer or server. . It should also be noted that in some alternative implementations, the functions noted in the various steps of the flowcharts or in the blocks of the block diagrams may not occur in the order noted in the drawings. For example, depending on the functionality involved, the two steps shown in succession, or two blocks may actually be executed substantially simultaneously, or the blocks may sometimes be Execute in reverse order.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention. It should also be considered as the scope of protection of the present invention.

Claims

Rights request

A data transmission method, comprising: the method: the source base station sends a sequence number SN status transmission message to the target base station, where the SN status transmission message is included to indicate that the source base station does not receive the acknowledgement The SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet of the character ACK feedback.

2. The method according to claim 1, wherein the SN status transmission message is a PDCP PDU packet that the source base station does not receive ACK feedback, and the SN information is a field PDCP PDU number „

The method according to claim 2, wherein the PDCP PDU packet further includes a field F for indicating whether it is necessary to transmit SN information corresponding to a PDCP PDU packet that does not receive ACK feedback.

4. The method according to claim 3, wherein the PDCP PDU packet further includes a field for counting PDCP PDU packets for which the source base station does not receive ACK feedback.

The method according to claim 1, wherein the SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes an SN corresponding to a PDCP PDU packet that the source base station does not receive ACK feedback. information.

The method according to any one of claims 1 to 2, wherein the method further comprises the step of: the source base station performing data forwarding in the following order: firstly, PDCP that does not receive ACK feedback The PDU packet is forwarded to the target base station, and then the PDCP service data unit SDU packet is forwarded to the target base station.

The method according to any one of claims 1 to 5, wherein the method is applied to a relay architecture defined by the 3GPP TR 36.806 protocol.

A data transmission method, the method comprising the steps of: the target base station receiving a sequence number SN status transmission message from the source base station, where the SN status transmission message is included to indicate that the source base station does not receive the acknowledgement The SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet of the character ACK feedback;

Ii—the target station report ii-S letter, for receiving 刭^ PDCP industry preparation* according to the unit SDT The package assigns a serial number.

The method according to claim 8, wherein the SN information is a field PDCP PDU number „

The method according to claim 9, wherein the PDCP PDU packet further includes a field for indicating whether the SN information corresponding to the PDCP PDU packet that does not receive the ACK feedback needs to be delivered. .

The method according to claim 10, wherein the PDCP PDU packet further includes a field for counting PDCP PDU packets for which the source base station does not receive ACK feedback.

The method according to claim 8, wherein the SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes an SN corresponding to a PDCP PDU packet that the source base station does not receive ACK feedback. information.

The method according to any one of claims 8, 9, and 12, wherein the target base station further includes a step before or after assigning a sequence number to the received PDCP SDU packet according to the SN information. The target base station performs PDCP layer processing on the data forwarded by the source base station according to the following sequence: first processing the PDCP PDU packet that is not received by the source base station and not receiving the ACK feedback, and then processing the PDCP SDU packet forwarded by the source base station. .

The method according to any one of claims 8 to 12, wherein the method is applied to a relay architecture defined by the 3GPP TR 36.806 protocol.

An apparatus for data transmission, the apparatus, comprising: a sending unit, configured to send an SN status transmission message, where the SN status transmission message is included to indicate that the source base station does not receive the acknowledgement character ACK The SN information corresponding to the fed back packet data convergence protocol PDCP protocol data unit PDU packet.

The device according to claim 15, wherein the SN status transmission message is a PDCP PDU packet that the source base station does not receive ACK feedback, and the SN information is a field PDCP PDU number; or

The device according to claim 15 or 16, wherein the device further comprises a forwarding unit, wherein the forwarding unit is configured to perform data forwarding according to the following sequence: first forwarding the PDCP PDU packet that does not receive the ACK feedback Giving the target base station, and then forwarding the PDCP service data unit SDU packet to the target base station.

A device for data transmission, the device comprising: a receiving unit, configured to receive an SN state transmission message sent by a source base station, where the SN state transmission message is associated with a data unit PDU packet SN information; an allocating unit, configured to allocate a sequence number to the received PDCP service data unit SDU packet according to the SN information.

The device according to claim 18, wherein the SN status transmission message is a PDCP PDU packet that the source base station does not receive ACK feedback, and the SN information is a field PDCP PDU number; or

The device according to claim 18 or 19, wherein the device further comprises a processing unit, configured to allocate, by the allocation unit, a serial number to the received PDCP service data unit SDU packet according to the SN information Before or after, performing PDCP layer processing on the data forwarded by the source base station according to the following sequence: first processing the unreceived ACK feedback forwarded by the source base station

The PDCP PDU packet is then processed by the source base station to forward the PDCP SDU packet.

A communication system for data transmission, characterized in that the communication system comprises the device according to any one of claims 15 to 17 and the device according to any one of claims 18 to 20.