CN103888215A - Data transmission method, device and communication system - Google Patents

Abstract

The invention relates to the technical field of communication, and discloses a data transmission method, which comprises the following steps: and the source base station sends a serial number SN state transmission message to the target base station, wherein the SN state transmission message comprises SN information corresponding to a packet data convergence protocol PDCP protocol data unit PDU packet used for indicating that the source base station does not receive acknowledgement character ACK feedback. The invention also provides a device for data transmission and a communication system. The invention ensures that the PDCP SDU packet which is already distributed with the sequence number by the source eNB can be distributed with the same sequence number on the target eNB after the data forwarding is carried out by the source eNB by including the sequence number information which is used for indicating that the source base station does not receive the PDCP PDU packet corresponding to the confirmation in the sequence number state transmission message sent by the source base station, thereby ensuring the continuity of the PDCP SDU packet.

Description

Data transmission method, device and communication system

technical field

The present invention relates to the technical field of communication, in particular to a data transmission method, device and communication system.

Background technique

Figure 1 shows the handover process between evolved Node Bs (Evolved Node B, eNB) in the existing Long Term Evolution (LTE) system. In the process of Figure 1, in the Unacknowledged Mode (Unacknowledged Mode, UM) mode, when the user equipment (User Equipment, UE) switches from the source eNB to the target eNB, the IP packets cached in the source eNB can be forwarded to the target through the X2 interface The eNB may not forward it to the target eNB. When the target eNB performs packet data convergence protocol (PacketData Convergence Protocol, PDCP) layer processing on the buffer data, it restarts from PDCP sequence number (Sequence Number, SN)=0. In 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 eNode Bs, one is not through the PDCP layer The processed IP packets are the PDCP service data unit (Service data unit, SDU) packet, and the second is the PDCP protocol data unit (Protocol DataUnit, PDU) packet that has not received the feedback of the acknowledgment character (Acknowledgment, ACK). The ACK is fed back by the user equipment during uplink, and fed back by the base station during downlink.

A Relay architecture (called ALT-4) is proposed in 3GPP TR36.806. The protocol stacks of the control plane and the user plane of the ALT-4 are shown in Figure 2 and Figure 3 . For the user plane of the ALT-4 architecture, the data of the communication interface (Un) between the relay node and the eNB does not need to carry out IP, User Datagram Protocol (User Datagram Protocol, UDP), general packet radio service tunneling protocol-user plane Layer processing, but only needs to be processed to the PDCP layer, thereby shortening the processing delay of data transmission. However, when using ALT-4, since there is no transfer network layer (Transfer Net Layer, TNL), when data is forwarded, the target eNB cannot distinguish which data packets received from the X2 interface are PDCP SDU packets that have not been processed by the PDCP layer. Which data are PDCP PDU packets processed by the PDCP layer that have not received ACK feedback, which may cause disorder of the forwarded data when the target eNB performs SN association.

Contents of the invention

Embodiments of the present invention provide a data transmission method, device, and communication system, so that after the source eNB performs data forwarding, it can be ensured that the PDCP SDU packet that has been assigned a sequence number SN on the source eNB can still be assigned to the same SN on the target eNB , so as to ensure the continuity of PDCP SDU packets.

In order to solve the above technical problems, the embodiment of the present invention discloses the following technical solutions:

In the first aspect, a data transmission method is provided, the method comprising the steps: the source base station sends a serial number SN status transmission message to the target base station, and the SN status transmission message includes a character used to indicate that the source base station has not received the confirmation SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet fed back by the ACK.

In a first possible implementation manner of the first aspect, the SN status transmission message is a PDCP PDU packet for which the source base station has not received ACK feedback, and the SN information is a field PDCP PDU number.

The PDCP PDU packet also includes a field F for indicating whether to transmit the SN information corresponding to the PDCP PDU packet for which ACK feedback has not been received.

The PDCP PDU packet also includes a field for counting PDCP PDU packets for which the source base station has not received ACK feedback.

In the second possible implementation of the first aspect, the SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback .

The method also includes the step of: performing data forwarding at the source base station in the following order: first forwarding the PDCP PDU package that has not received ACK feedback to the target base station, and then forwarding the PDCP service data unit SDU package to the target base station.

The method is applied in the relay architecture defined by the 3GPP TR36.806 protocol.

In a second aspect, a data transmission method is provided, the method comprising the steps: the target base station receives a serial number SN status transmission message from the source base station, and the SN status transmission message includes a character used to indicate that the source base station has not received the confirmation character SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet fed back by the ACK;

The target base station assigns 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.

The PDCP PDU packet also includes a field F for indicating whether to transmit the SN information corresponding to the PDCP PDU packet for which ACK feedback has not been received.

The PDCP PDU packet also includes a field for counting PDCP PDU packets for which the source base station has not received ACK feedback.

In a second possible implementation of the second aspect, the SN status transmission message is a PDCP SN status report, and the PDCP SN status report includes the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback .

According to the SN information, before or after the target base station allocates a sequence number for the received PDCP SDU packet, it also includes a step: the target base station performs PDCP layer processing on the data forwarded by the source base station in the following order: first process The source base station forwards the PDCP PDU packet for which ACK feedback has not been received, and then processes the PDCP SDU packet forwarded by the source base station.

The method is applied in the relay architecture defined by the 3GPP TR36.806 protocol.

In a third aspect, a device for data transmission is provided, the device includes: a sending unit, configured to send an SN status transfer message, the SN status transfer message includes an ACK indicating that the source base station has not received an acknowledgment character ACK SN information corresponding to the fed back packet data convergence protocol PDCP protocol data unit PDU packet.

In the first possible implementation of the third aspect, the SN status transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback.

In a second possible implementation of the third aspect, the device further includes a forwarding unit, and the forwarding unit is configured to forward data in the following order: first, forward the PDCP PDU packets for which ACK feedback has not been received to the The target base station then forwards the PDCP service data unit SDU packet to the target base station.

According to a fourth aspect, a device for data transmission is provided, the device includes: a receiving unit, configured to receive an SN state transmission message sent by a source base station, and the SN state transmission message includes a message indicating that the source base station has not received SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet fed back by the confirmation character ACK;

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

In the first possible implementation of the fourth aspect, the SN status transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback.

In a second possible implementation of the fourth aspect, the device further includes a processing unit, configured for the allocation unit to assign a sequence number before or after 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 in the following order: first process the PDCP PDU packets forwarded by the source base station for which ACK feedback has not been received, and then process the PDCP SDU packets forwarded by the source base station.

In a fifth aspect, a communication system for data transmission is provided, the communication system includes the device in any possible implementation manner in the above third aspect, and the device in any possible implementation manner in the fourth aspect .

In a sixth aspect, a system for data transmission is provided, the system comprising: a network interface, configured to send an SN status transfer message, the SN status transfer message includes an ACK used to indicate that the source base station has not received an acknowledgment character ACK SN information corresponding to the fed back packet data convergence protocol PDCP protocol data unit PDU packet.

In the first possible implementation of the sixth aspect, the SN status transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback.

In a second possible implementation of the sixth aspect, the system further includes a processor, and the processor is configured to perform data forwarding in the following order: first, forward the PDCP PDU packets for which ACK feedback has not been received to the target The base station then forwards the PDCP service data unit SDU packet to the target base station.

In a seventh aspect, a system for data transmission is provided. The system includes: a network interface, configured to receive an SN state transmission message sent by a source base station, and the SN state transmission message includes a message indicating that the source base station has not received SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet fed back by the confirmation character ACK;

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

In the first possible implementation of the seventh aspect, the SN status transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback.

The system also includes a processor, used for the controller to perform PDCP on the data forwarded by the source base station in the following order before or after assigning a sequence number to the received PDCP service data unit SDU packet according to the SN information Layer processing: first process the PDCP PDU packets forwarded by the source base station without receiving ACK feedback, and then process the PDCP SDU packets forwarded by the source base station.

The above technical solution has the following advantages: the present invention includes the SN information used to indicate that the source base station has not received the SN information corresponding to the acknowledgment PDCP PDU packet in the serial number SN status transmission message sent by the source base station, so that after the source eNB performs data forwarding , it can ensure that the PDCP SDU packet that has been assigned a sequence number SN on the source eNB can also be assigned to the same SN on the target eNB, thereby ensuring the continuity of the PDCP SDU packet.

Description of drawings

FIG. 1 is a flow chart of handover between eNBs in an existing LTE system;

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

Fig. 3 is ALT-4 user name protocol stack;

Fig. 4 is a schematic diagram of an existing PDCP PDU packet format;

Fig. 5 is a schematic diagram of the PDCP PDU packet format used in one embodiment of the method of the present invention;

Fig. 6 is a block diagram of an embodiment of the device for data transmission of the present invention;

FIG. 7 is a block diagram of another embodiment of the device for data transmission of the present invention;

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

Fig. 9 is a block diagram of an embodiment of the system for data transmission of the present invention;

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

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

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

As shown in Fig. 1, the data transmission method of the present invention mainly improves the sequence number SN status transmission message sent in step 8, so that after the UE confirms that the handover is successful (step 11), the target base station (in this implementation eNB in the example) will not be out of order when receiving data from the source base station (eNB in this embodiment).

The embodiment of the first data transmission method of the present invention describes the process of data transmission in step 8 in FIG. 1 from the source base station side. The method includes the steps: the source base station sends a serial number SN state transmission message to the target base station, and the SN state transmission The message includes the SN information corresponding to the PDCP PDU packet (the PDCP PDU packet refers to the data packet processed by the PDCP layer) used to indicate that the source base station has not received the acknowledgment character ACK feedback. The SN status transmission message is a PDCP PDU packet for which the source base station has not received ACK feedback, and the SN information is a field PDCP PDUnumber.

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

The format of the original PDCP PDU packet 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 PDCP SN is the interface between the PDCP PDU packet passing through the RN and the target eNB When the Un interface is transmitting, the serial number generated by the PDCP layer on the Un interface is used to ensure the correctness of the serial number of the PDCP PDU packet transmitted by the Un interface. PDCPSN (cont.) is the count value of the transmitted PDCP PDU packet, Data and ellipsis It is the data part of the PDCP PDU packet, and Oct represents octal.

The format of the modified PDCP PDU packet is shown in Figure 5. Among them, R, which was originally a reserved field, is modified to be an F field: occupying 1 bit, used to indicate whether to transmit the PDCP PDU that the source base station has not received ACK feedback on the Un interface SN information corresponding to the package. That is, when the F field is 0, it means that the SN information corresponding to the PDCP PDU packet that the source base station has not received ACK feedback on the Un interface does not need to be transmitted; when it is 1, it indicates that the PDCP that the source base station has not received ACK feedback on the Un interface needs to be transmitted. The SN information corresponding to the PDU packet; the newly added PDCP PDU number field: occupies 12 bits, indicating that the source base station has not received the SN information corresponding to the PDCP PDU packet fed back by the ACK. In Figure 5, the newly added PDCP PDU number (cont.) is used to count the PDCP PDU packets that the source base station has not received ACK feedback, and the ellipsis indicates data. In this case, when F=1, reading the 12-bit PDCP DPU number can obtain the sequence number of the PDCP PDU packet that the source base station has not received the ACK feedback, because the sending order of the PDCP PDU packet that has not received the ACK feedback The priority is higher than the PDCP SDU packet, so according to the sequence number in the PDCP PDU packet received first, the sequence number of the PDCP SDU packet received later can be assigned to ensure the continuity of the PDCP SDU packet.

For example: the source node wants to send data packets 1, 2, 3, 4, and 5, among which data packets 4 and 5 are PDCP SDU packets. After sending data packets 1, 2, and 3, the ACK feedback of PDCP PDU packets 1 and 2 is received. , but no ACK feedback for PDCP PDU packet 3 was received. 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, and 4. Since the SN=3 of the PDCP PDU packet is specified in the PDCP PDU packet, After receiving the PDCP PDU packet, the target node assigns sequence numbers 4 and 5 to the PDCP SDU packet in the order of the received PDCP SDU packets, thus 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 in FIG. 1 from the target base station side. The method includes the steps: the target base station receives a serial number SN state transmission message from the source base station, and the SN state The transmission message includes the SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet used to indicate that the source base station has not received the acknowledgment character ACK feedback;

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

After introducing the ALT-4 relay architecture, since the SN information corresponding to the PDCP SDU packet cannot be carried when the PDCP SDU packet is forwarded on the Un interface, the PDCP SN transmitted by the downlink X2 interface after the introduction of the ALT-4 relay architecture The status report is changed to include the SN information corresponding to the PDCP PDU packet that has not received ACK feedback. The PDCP SDU packet has not been processed by the PDCP layer, and there is no serial number assigned. Its serial number is allocated by the target base station, and when it is sent, its priority is the lowest, and the PDCP layer has not received ACK feedback. The priority of the PDCP PDU packet is higher, so the data forwarding mechanism of the source base station is: the source base station first forwards the data of the PDCP PDU packet that has not received the ACK feedback, and then forwards the data of the PDCP SDU packet. AM mode, so the target base station can receive the data forwarded by the source base station in sequence. Then the target base station can use the SN information delivered in the PDCPSN status report to ensure that the PDCP SDU packet that has been assigned a sequence number on the source base station can still be assigned the same sequence number on the target base station, ensuring the continuity of the PDCP SDU packet. The forwarded PDCP SDU data can be processed at the PDCP layer on the Un interface in sequence.

For example: the source node wants to send data packets 1, 2, 3, 4, and 5, among which data packets 4 and 5 are PDCP SDU packets. After sending data packets 1, 2, and 3, the ACK feedback of PDCP PDU packets 1 and 2 is received. , but no ACK feedback for PDCP PDU packet 3 was received. At this time, the source node needs to resend data packets 3, 4, and 5 to the target node in the order of data packets 3, 4, 5 or 3, 5, and 4, because the PDCP SN status report indicates that the SN of the PDCP PDU packet is 3 After receiving the PDCP PDU packet, the target node assigns sequence numbers 4 and 5 to the PDCP SDU packet in the order of the received PDCP SDU packets, thus ensuring the continuity of the PDCP SDU packets.

The data transmission method of the present invention can be applied to the relay architecture defined by the 3GPP TR36.806 protocol.

Corresponding to the embodiments of the data transmission method of the present invention, the present invention also provides embodiments of a device for data transmission and a communication system.

Referring to FIG. 6 , it is a block diagram of an embodiment of an apparatus for data transmission according to the present invention, and the apparatus describes the process of data transmission from the side of the source base station.

The device includes: a sending unit 610, configured to send an SN status transfer message, the SN status transfer message including SN information corresponding to a PDCP PDU packet indicating that the source base station has not received ACK feedback;

Forwarding unit 620, the forwarding unit is used to perform data forwarding in the following order: firstly forward the PDCP PDU package that has not received ACK feedback to the target base station, and then forward the PDCP service data unit SDU package to the target base station .

As an implementation manner, the SN status transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback.

Referring to FIG. 7 , it is a block diagram of another embodiment of the device for data transmission according to the present invention, which describes the process of data transmission from the target base station side.

The device includes: a receiving unit 710, configured to receive an SN status transmission message sent by a source base station, wherein the SN status transmission message includes SN information corresponding to a PDCP PDU packet indicating that the source base station has not received an acknowledgment character ACK feedback; and

The allocation 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 used for the allocation unit 720 to perform PDCP layer processing on the data forwarded by the source base station in the following order before or after allocating a sequence number for the received PDCP service data unit SDU packet according to the SN information: First process the PDCP PDU packet forwarded by the source base station without receiving ACK feedback, and then process the PDCP SDU packet forwarded by the source base station.

As an implementation manner, the SN status transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback.

Referring to FIG. 8 , it is a block diagram of an embodiment of a communication system for data transmission according to the present invention.

The communication system includes: any embodiment of the device 810 for data transmission described above from the source base station side, and any embodiment of the device 820 for data transmission described from the side of the target base station, for example, the communication The system may be an LTE system.

Referring to FIG. 9 , it is a block diagram of an embodiment of the system for data transmission of the present invention.

The system includes: a system for data transmission is provided, the system includes: a network interface 910, configured to send an SN status transfer message, and the SN status transfer message includes a message indicating that the source base station has not received ACK feedback SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet;

Processor 920, the processor 920 is configured to perform data forwarding in the following order: firstly forward the PDCP PDU package that has not received ACK feedback to the target base station, and then forward the PDCP service data unit SDU package to the target base station base station.

As an implementation manner, the SN status transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback.

Referring to FIG. 10 , it is a block diagram of another embodiment of the system for data transmission of the present invention.

The system includes: a network interface 1010, configured to receive the SN status transfer message sent by the source base station, and the SN status transfer message includes a packet data convergence protocol PDCP protocol data unit used to indicate that the source base station has not received the acknowledgment character ACK feedback SN information corresponding to the PDU packet;

The controller 1020 is configured to assign a sequence number to the received PDCP service data unit SDU packet according to the SN information;

The processor 1030 is configured to perform PDCP layer processing on the data forwarded by the source base station in the following order before or after the controller 1020 assigns a sequence number to the received PDCP service data unit SDU packet according to the SN information: First process the PDCP PDU packet forwarded by the source base station without receiving ACK feedback, and then process the PDCP SDU packet forwarded by the source base station.

As an implementation manner, the SN status transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback.

It can be seen from the above embodiments that in the present invention, the SN information used to indicate that the source base station has not received the SN information corresponding to the acknowledgment PDCP PDU packet is included in the serial number SN status transmission message sent by the source base station, so that data is forwarded at the source eNB Afterwards, it can be guaranteed that the PDCP SDU packet that has been assigned a sequence number SN on the source eNB can also be assigned to the same SN on the target eNB, thereby ensuring the continuity of the PDCP SDU packet.

Those of ordinary skill in the art will understand that various aspects of the present invention, or possible implementations of various aspects, may be embodied as systems, methods or computer program products. Accordingly, aspects of the present invention, or possible implementations of various aspects, may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, etc.), or an embodiment combining software and hardware aspects, described in These are collectively referred to herein as "circuits," "modules," or "systems." In addition, aspects of the present invention, or possible implementations of various aspects, may take the form of computer program products, and computer program products refer to computer-readable program codes stored in computer-readable media.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. Computer-readable storage media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or devices, or any appropriate combination of the foregoing, such as random access memory (RAM), read-only memory (ROM), Erase Programmable Read-Only Memory (EPROM or Flash), Fiber Optic, Portable Read-Only Memory (CD-ROM).

The processor in the computer reads the computer-readable program code stored in the computer-readable medium, so that the processor can execute the functional actions specified in each step in the flow chart, or a combination of steps; A device that performs functional actions specified in each block or a combination of blocks.

The computer readable program code may execute 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 a remote computer, or entirely on the remote computer or server . It should also be noted that, in some alternative implementations, the functions noted at the steps in the flowcharts or blocks in the block diagrams may occur out of the order noted in the figures. For example, two steps, or two blocks shown in succession, may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and replacements can also be made, these improvements and replacements It should also be regarded as the protection scope of the present invention.

Claims (21)

1. A data transmission method, characterized in that, the method comprises the steps: the source base station sends a serial number SN state transmission message to the target base station, and the SN state transmission message includes a message for indicating that the source base station has not received an acknowledgment SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet fed back by the character ACK. 2. The method according to claim 1, wherein the SN status transfer message is a PDCP PDU packet for which the source base station has not received ACK feedback, and the SN information is a field PDCP PDU number. 3. The method according to claim 2, wherein the PDCP PDU packet further includes a field F for indicating whether to transmit the SN information corresponding to the PDCP PDU packet that has not received the ACK feedback. 4. The method according to claim 3, wherein the PDCP PDU packet also includes a field for counting PDCP PDU packets that have not received ACK feedback for the source base station. 5. 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 the SN corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback information. 6. The method according to any one of claims 1, 2, and 5, characterized in that, the method further comprises the step of: the source base station forwards data in the following order: first, the PDCP that has not received 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. 7. The method according to any one of claims 1 to 5, wherein the method is applied in the relay architecture defined by the 3GPP TR36.806 protocol. 8. A data transmission method, characterized in that the method comprises the steps: the target base station receives a serial number SN status transmission message from the source base station, and the SN status transmission message includes a message indicating that the source base station has not received an acknowledgment SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet fed back by the character ACK; The target base station assigns a sequence number to the received PDCP service data unit SDU packet according to the SN information. 9. The method according to claim 8, wherein the SN information is a field PDCP PDU number. 10. The method according to claim 9, wherein the PDCP PDU packet further includes a field F for indicating whether to transmit the SN information corresponding to the PDCP PDU packet for which ACK feedback has not been received. 11. 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 has not received ACK feedback. 12. 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 the SN corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback information. 13. The method according to any one of claims 8, 9, 12, wherein the target base station further comprises the step of assigning a sequence number to the received PDCP SDU packet according to the SN information, before or after : The target base station performs PDCP layer processing on the data forwarded by the source base station in the following order: first process the PDCP PDU packets forwarded by the source base station without receiving ACK feedback, and then process the PDCP SDU packets forwarded by the source base station. 14. The method according to any one of claims 8 to 12, wherein the method is applied to the relay architecture defined in the 3GPP TR36.806 protocol. 15. A device for data transmission, characterized in that the device comprises: a sending unit, configured to send an SN status transfer message, the SN status transfer message includes an ACK indicating that the source base station has not received an acknowledgment character SN information corresponding to the fed back packet data convergence protocol PDCP protocol data unit PDU packet. 16. The device according to claim 15, wherein the SN state transmission message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback. 17. The device according to claim 15 or 16, wherein the device further comprises a forwarding unit configured to forward data in the following order: first forward the PDCP PDU packets that have not received ACK feedback to the target base station, and then forward the PDCP service data unit SDU packet to the target base station. 18. A device for data transmission, characterized in that the device comprises: a receiving unit, configured to receive the SN status transmission message sent by the source base station, and the SN status transmission message includes a message indicating that the source base station has not received SN information corresponding to the packet data convergence protocol PDCP protocol data unit PDU packet fed back by the confirmation character ACK; The allocation unit is configured to allocate a sequence number for the received PDCP service data unit SDU packet according to the SN information. 19. The device according to claim 18, wherein the SN status transfer message is a PDCP PDU packet for which the source base station has not received 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 the SN information corresponding to the PDCP PDU packet for which the source base station has not received ACK feedback. 20. The device according to claim 18 or 19, wherein the device further comprises a processing unit, configured for the allocation unit to allocate a sequence number for the received PDCP service data unit SDU packet according to the SN information Before or after, the PDCP layer processing is performed on the data forwarded by the source base station in the following order: first process the PDCP PDU packets forwarded by the source base station without receiving ACK feedback, and then process the PDCP SDU packets forwarded by the source base station. 21. A communication system for data transmission, characterized in that the communication system comprises the device according to any one of claims 15-17 and the device according to any one of claims 18-20.

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