WO2012024949A1

WO2012024949A1 - Data retransmission method and apparatus

Info

Publication number: WO2012024949A1
Application number: PCT/CN2011/074444
Authority: WO
Inventors: 任泰云
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-08-26
Filing date: 2011-05-20
Publication date: 2012-03-01
Also published as: CN102377553A

Abstract

The present invention discloses a data retransmission method and apparatus. The method includes: judging whether to add one to the number of Protocol Data Unit (PDU) retransmissions by comparing the Negative Acknowledgement (NACK) information received by a Radio Link Control (RLC) this time with the NACK information stored last time. The present invention also provides a data retransmission apparatus, which includes a comparison and judgment module for judging whether to add one to the number of PDU retransmissions by comparing the NACK information received by the RLC this time with the NACK information stored last time. With the present invention, the accuracy for counting the number of PDU retransmissions is ensured, and meanwhile, the frequency of reestablishment during the data transmission process is reduced, and the system reliability is enhanced.

Description

Data retransmission method and device

The present invention relates to a wireless communication technology, and in particular, to a data retransmission method and apparatus for a Long Term Evolution (LTE) system. Background technique

As shown in Figure 1, the Radio Link Control (RLC) protocol layer is located under the Packet Data Convergence Protocol (PDCP) layer in the LTE radio interface protocol stack. Media Access Control (MAC, Media) Above the Access Control layer is a sublayer of Layer 2 protocols for error recovery and flow control in 3G systems. The RLC sublayer provides segmentation and retransmission services for user service data and control data. The functions of the RLC sublayer include link control, delivery of upper layer (RRC/PDCP) Protocol Data Unit (PDU), reassembly, segmentation, re-segmentation and cascading, sequential delivery of PDUs to the upper layer, automatic repeat request (ARQ, Automatic Repeat Request) error correction, repetitive detection, flow control, protocol error detection and repair, RLC reconstruction, etc. The functions of the RLC sublayer are implemented by RLC entities, and each RLC entity can be configured into three modes by RRC (Radio Resource Control) for performing data transmission: transparent mode (TM, Transparent Mode), unacknowledged mode ( UM, Unacknowledged Mode) and acknowledgment mode (AM, Acknowledged Mode). In the three modes, the ARQ retransmission in the acknowledgment mode is that the receiver sends a status report to the sender, and the sender ACK_SN (Acknowledgement Sequence Number) and NACK-SN (Negative) in the advertisement according to the status. Acknowledgement Sequence Number) determines which PDUs have been acknowledged by the receiving end, and which PDUs or PDU fragments need to be retransmitted, thereby ensuring the reliability of data transmission.

In the prior art, in the process of constructing retransmission data in the RLC layer, the number of retransmissions needs to be If the number of retransmissions of a PDU reaches a maximum, the RRC layer needs to report the maximum number of retransmissions to initiate the RRC reestablishment process. But in the prior art, as long as it is

The retransmission of the PDU, whether it is the retransmission of the entire PDU or the retransmission of the PDU fragment, is recorded as a retransmission of the PDU, which may cause a processing exception in the following cases.

4, the RLC layer receives the scheduling result of the MAC layer, and the size of the TB block is 8192 bytes.

The RLC groups 8192 bytes of PDUs according to the size of the TB block and sends them to the peer. The PDU is PDU_1. However, the TB block is lost during transmission, and the channel quality deteriorates at this time. Thereafter, the size of the scheduling result TB of the MAC is 100 bytes each time, and the RLC constructs a retransmission PDU through the PDU_1, each time the configurable size If the TB is sent to the peer, the peer can receive the retransmitted PDU fragment after the PDU_1 is split, but the PDU_1 needs to be sent through the retransmission packet. After more than 80 times, it can be sent out. According to the processing method of the existing system, how the RLC layer handles the maximum number of retransmissions, and sends an error indication to the RRC layer to initiate the re-establishment process, but this is a normal situation. This initiates the rebuild process. SUMMARY OF THE INVENTION The present invention is to provide a data retransmission method and apparatus, which solves the problem that the bandwidth of the radio link is wasted due to the deficiencies in the process of constructing the RLC layer in the LTE existing system due to retransmission of data packets.

The present invention provides a data retransmission method for determining whether to increase the number of retransmissions of a PDU by comparing the NACK information received by the RLC with the last saved NACK information.

Further, the comparison is specifically: if the size of the retransmission data included in the received NACK information is smaller than the size of the retransmission data in the last saved NACK information, the retransmission data is constructed only by the NACK information, and the PDU is not The number of retransmissions is incremented by one; otherwise, after the retransmission data is constructed by the NACK information, the number of retransmissions of the PDU is incremented by one.

Further, the method further includes: after saving the NACK information received this time, according to the TB of the MAC The information fills the TB block with the constructed retransmission PDU and sends the TB block to the receiving end.

Further, the method further includes: receiving, by the RLC, the status report sent by the peer end, and obtaining the NACK information by parsing the status report.

The present invention further provides a data retransmission apparatus, comprising a comparison decision module, configured to determine whether to increase the number of retransmissions of the PDU by one by comparing the NACK information received by the RLC and the last saved NACK information.

Specifically, the comparison decision module is further configured to: if the size of the retransmission data included in the received NACK information is smaller than the size of the retransmission data in the last saved NACK information, construct the retransmission data only by using the NACK information, The number of retransmissions of the PDU is not increased by one; otherwise, after the retransmission data is constructed by the NACK information, the number of retransmissions of the PDU is incremented by one.

When the retransmission count value is incremented by one, the present invention performs comparison with the last NACK information to ensure the correctness of the retransmission PDU count; at the same time, the frequency of reconstruction in the data transmission process is reduced, and the frequency is enhanced. System reliability. DRAWINGS

Figure 1 is a schematic diagram of the structure of the RLC status report.

Figure 2 is a schematic diagram of the RLC retransmission data construction process.

3 is a flow chart of an embodiment of a method of the present invention.

4 is a schematic structural view of a data retransmission device of the present invention. detailed description

The present invention determines whether the size of the retransmission data included in the NACK information received and the size of the retransmission data in the last saved NACK information is compared when the RLC layer receives the status report constructing the retransmission message. The number of retransmissions of the PDU is increased by one. The invention is described in detail below with reference to the accompanying drawings and embodiments.

FIG. 2 is a flowchart of constructing an RLC retransmission data according to the present invention, as shown in FIG. 2, specifically including: Step 201: The RLC sending side receives a status report sent by the opposite end.

Step 202: The RLC parses the status report to obtain NACK information.

Step 203: Obtain a length RetransLen_l of the PDU retransmission part indicated by the NACK information received by the RLC and a retransmission part length RetransLen_2 indicated by the last saved corresponding NACK information.

Step 204: Compare the sizes of RetransLen_l and RetransLen_2. If RetransLen_l 'J is in RetransLen_2, go to step 205. Otherwise, go to step 206.

Step 205: The RLC layer constructs a retransmission PDU according to the NACK information received this time, and then saves the NACK information received this time, and then performs step 207.

Step 206: Construct a retransmission PDU according to the received NACK information, and add 1 to the retransmission number of the PDU corresponding to the NACK information, and then save the NACK information received this time, and then perform step 207.

Step 207: Fill the TB block with the constructed retransmission PDU according to the TD information of the MAC, and send the TB block to the receiving end.

Method embodiment

FIG. 3 shows an embodiment of a data retransmission method according to the present invention. This embodiment is an example of a retransmission data structure of a radio link control layer in an LTE system. First, it is assumed that: (1) the RLC transmitting side sends Three PDUs of 8192 bytes are recorded as PDU_1, PDU_2 and PDU3. Due to the link, the PDU_1 is lost during transmission, and the receiving side of the RLC does not receive the PDU_1. (2) The maximum number of retransmissions is 3.

As shown in Figure 3, the specific steps of the RLC layer retransmission data construction are as follows:

Step 301: The RLC sending side receives the status report Status_l sent by the peer end.

Step 302: The RLC sending side parses the status report Status_l to obtain the Nack information, indicating that the PDU_1 is not received as a whole.

Step 303, because the NACK information is not received last time, the RLC transmitting side will PDU_1 The NACK is saved, and the PDU as a whole is used as a retransmission PDU according to the NACK indication, and the number of retransmissions of the PDU is PdulRetransCount.

Step 304: The RLC sends the scheduling result of the MAC, and the size of the TB is 4000 bytes. The RLC adds the 1-4000 byte data portion of the retransmission 4 bytes to the TB block for transmission.

Step 305: The RLC sending side receives the status report Status_2 sent by the peer end.

Step 306: The RLC sending side parses the status report Status_2, and obtains the Nack information, indicating that the 4001-8192 bytes are not received.

Step 307: The RLC transmitting side compares the current NACk information with the last NACK information, and finds that the length of the retransmission part indicated by the current NACK information is smaller than the length of the retransmission part indicated by the last NACK information, and the number of retransmissions is not PdulRetransCount. The addition operation is performed, and the retransmission PDU is constructed only according to the 4001-8192 byte data portion indicated by the NACK information. Then wait for the MAC scheduling opportunity.

Step 308: The RLC sending side receives the scheduling result of the MAC, where the size of the TB is 5000. The RLC adds the bytes of the retransmitted message 4001-8192 to the TB block and sends it out. However, due to the link, the TB block is lost during transmission and the receiving side of the RLC is not received.

Step 309: The RLC sending side receives the status report Status_3 sent by the peer.

Step 310: The RLC sending side parses the status report Status_3, and obtains the Nack information, indicating that the 4001-8192 bytes are not received.

Step 311: The RLC transmitting side compares the current NAC K information with the last NACK information, and finds that the length of the retransmission part indicated by the current NACK information is equal to the length of the retransmission part indicated by the last NACK information, and the number of retransmissions is first. PdulRetransCount performs an operation of adding 1 to determine that PdulRetransCount is 2, less than 3, and does not initiate reconstruction. The retransmitted PDU is constructed according to the 4001-8192 byte data portion indicated by the NACK information. Then wait for the MAC scheduling opportunity.

Step 312: The RLC sending side receives the scheduling result of the MAC, where the size of the TB is 5000 bytes. The RLC adds the bytes of 4001-8192 that are retransmitted to the TB block and sends them out. Step 313: The RLC sending side receives the status report Status_4 sent by the peer end.

Step 314, the RLC sending side parses the status report Status_4, and finds that the PDU_1 has been completely received, and the RLC deletes the NACK information saved by the PDU_1.

Device embodiment

4 is a schematic structural diagram of a device according to the present invention. As shown in FIG. 4, the data retransmission device includes a comparison decision module, which is used to compare the NACK information received by the RLC and the last saved NACK information. Whether to increase the number of retransmissions of the PDU by one. Specifically, if the size of the retransmission data included in the received NACK information is smaller than the size of the retransmission data in the last saved NACK information, the retransmission data is constructed only by the NACK information, and the number of retransmissions of the PDU is not increased by one. Operation; Otherwise, after the retransmission data is constructed by the NACK information, the number of retransmissions of the PDU is incremented by one.

The data retransmission apparatus further includes: a storage module, configured to save the NACK information received this time; a receiving module, configured to receive, by the RLC transmitting side, a status report sent by the peer end; and a parsing module, configured to perform the RLC parsing the status report NACK information.

When the retransmission count value is incremented by one, the present invention performs comparison with the last NACK information to ensure the correctness of the retransmission PDU count; at the same time, the frequency of reconstruction in the data transmission process is reduced, and the frequency is enhanced. System reliability.

The above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim

A data retransmission method, characterized in that it is determined whether the number of retransmissions of the protocol data unit PDU is increased by one by comparing the negative acknowledgement NACK information received by the RLC and the last saved NACK information.

The data retransmission method according to claim 1, wherein the determining whether to add 1 to the number of retransmissions of the protocol data unit PDU is: if the size of the retransmission data included in the NACK information received this time If the size of the retransmission data in the last saved NACK information is smaller, the data is retransmitted only by the NACK information, and the number of retransmissions of the PDU is not increased. Otherwise, after the data is retransmitted by the NACK information, the PDU is retransmitted. The number of retransmissions is increased by 1.

The data retransmission method according to claim 2, wherein the method further comprises:

The NACK information received this time is saved, and the TB block is filled with the constructed retransmission PDU according to the transport block TB information of the medium access control MAC, and the TB block is sent to the receiving end.

The data retransmission method according to claim 1, wherein the method further comprises: receiving, by the RLC, the status report sent by the peer end, and parsing the status report to obtain the NACK information.

A data retransmission apparatus, comprising: a comparison decision module, configured to determine whether to increase the number of retransmissions of the PDU by one by comparing the NACK information received by the RLC and the last saved NACK information.

The apparatus according to claim 5, wherein the comparison decision module is further configured to: if the size of the retransmission data included in the NACK information received this time is smaller than the retransmission data in the last saved NACK information For the size, the retransmission data is constructed only by the NACK information, and the number of retransmissions of the PDU is not increased by 1; otherwise, after the retransmission data is constructed by the NACK information, the number of retransmissions of the PDU is incremented by one.

The device according to claim 6, further comprising: a storage module, In order to save the NACK information received this time.

The device according to claim 5, further comprising: a receiving module, configured to receive, by the RLC transmitting side, a status report sent by the peer end, and a parsing module, configured by the RLC to parse the status, to obtain the NACK information .