WO2013159516A1

WO2013159516A1 - Wireless side tcp data retransmission method and device

Info

Publication number: WO2013159516A1
Application number: PCT/CN2012/085231
Authority: WO
Inventors: 柴新旺
Original assignee: 大唐移动通信设备有限公司
Priority date: 2012-04-28
Filing date: 2012-11-26
Publication date: 2013-10-31
Also published as: CN102664718A; CN102664718B

Abstract

Disclosed in an embodiment of the present invention are a wireless side TCP data retransmission method and device, comprising: by applying the technical solution in the embodiment of the present invention, when a TCP entity receives an uplink message transmitted by a terminal device and containing a Dup ACK message, and if the TCP entity determines that an RLC layer has transmitted to the terminal device all the fragment packets of a data packet corresponding to the Dup ACK message and has received an ACK message returned by the terminal device, then counting and accumulating the Dup ACK messages; and when the count value reaches 2, retransmitting the data packet corresponding to the Dup ACK message, so as to screen the Dup ACK of the terminal device by flexibly utilizing the local data buffering and retransmission characteristics of the TCP entity and in combination with the reliable transmission characteristic of the RLC, and quickly retransmit the TCP layer data, so that the wireless side as an agency on the TCP can accurately determine whether the data packet requires the retransmission of the TCP layer, thus improving TCP performance and air interface resource utilization rate, and avoiding wasting system resources caused by unnecessary data retransmission.

Description

Method and device for wireless side TCP data retransmission

The present invention relates to the field of communications technologies, and in particular, to a method and device for wireless side TCP data retransmission. Background technique

TCP (Transmission Control Protocol) is a connection-oriented (connection-oriented), reliable, byte-based transport layer transport protocol.

On the radio side of a RNC (Radio Network Controller) with a TCP proxy function or a 3G (3rd Generation, 3rd Generation, 3rd Generation Mobile Telecommunications) terminal with a TCP entity, due to air packet loss and non-sequential delivery, The terminal receives a large number of out-of-order packets. The TCP entity corresponding to the terminal sends a Dup ACK (repeated acknowledgement) or SACK (selective acknowledgement) after receiving the out-of-order packet, indicating that a certain packet is lost.

In fact, these packets are divided into many small packets for transmission in the air interface. Due to the discarding of a small packet, the entire large packet cannot be delivered to the TCP entity of the terminal. At this time, the TCP entity of the terminal sends a Dup ACK or SACK, requesting the RNC side. The TCP proxy retransmits the packet data. After the packet is lost, it will be retransmitted at the RLC (Radio Link Control) layer. When the retransmitted packet is correctly received by the terminal, the entire packet is handed over to the TCP layer of the terminal.

However, if the RNC's TCP layer retransmits the packet data at this time, it will cause the packet to be repeatedly transmitted in the air interface, resulting in waste of air interface resources and bandwidth.

In the above process, Dup ACK or SACK is the TCP protocol to inform the sender that data loss can be used in two ways:

One way is to continuously receive 3 Dup ACKs (a total of 4 ACKs have the same acknowledgment number), indicating that the data packet receiving end of the acknowledgment number is not received; another way is that SACK directly tells the sender which data is received. , which data was not received.

For the unreceived data, retransmission processing is required. Currently, the TCP proxy has a large processing for retransmission. Mostly, according to the retransmission mechanism of TCP protocol or the improvement of TCP retransmission mechanism, including: (1) TCP protocol fast retransmission algorithm

If the sender continuously receives 3 Dup ACKs (a total of 4 ACKs have the same acknowledgment number) before the retransmission timer expires, it is highly probable that a certain packet of data has been lost, and the fast retransmission algorithm is started immediately. That is, the packet data is immediately retransmitted.

(2) Retransmission timer

When TCP sends a segment, it creates a retransmission timer for a specific segment based on RTT (Round-Trip Time). If the acknowledgment of the segment is received before the timer expires, the timer is revoked; if the acknowledgment for the segment is not received before the timer expires, the segment is retransmitted, and Clear the timer.

(3) Power retransmission algorithm

This algorithm is an improvement on the fast retransmission algorithm. If 3 Dup ACKs are received before the retransmission timer expires (-a total of 4 ACKs have the same acknowledgment number), the packet is retransmitted immediately and continues to be received later. 3 Dup ACKs, no longer retransmitted, until 8 ACKs are received with the same acknowledgment number, the packet is retransmitted, and subsequent 16 ACKs have the same acknowledgment number before retransmitting the packet... ... thus avoiding unnecessary unnecessary multiple retransmissions.

In the process of implementing the present invention, the inventors have found that at least the following problems exist in the prior art: The above three methods, the TCP protocol fast retransmission algorithm and the retransmission timer are part of the TCP protocol, and the power retransmission algorithm is based on fast An improvement in the retransmission algorithm. These methods have great limitations in solving the problem of whether the wireless side needs to retransmit data packets. The specific analysis is as follows:

(1) TCP protocol fast retransmission algorithm, this is the implementation method specified by the TCP protocol. The drawback of this method is obvious. In the case of poor wireless environment, the data packet sent by the TCP entity is divided into multiple in the RLC. If a small packet is lost, and the process of retransmitting these small packets takes a certain amount of time or the packets are repeatedly discarded in the air interface, the terminal will send a large number of Dup ACKs. If the fast retransmission algorithm is used, the entire data packet Being sent non-stop, wasting bandwidth and air interface resources.

(2) The method of retransmission timer has limitations in the wireless environment, mainly because the RTT is a very large value in the air interface, and the prediction according to the previous value is often inaccurate. If the RTT time prediction is short, It will lead to unnecessary retransmission, waste bandwidth and air interface resources; if the RTT time prediction is long, the real-time performance will be poor first, and then the transmission window will be full, which will also cause the air interface to be idle, resulting in unnecessary waste of air interface resources.

(3) The power retransmission algorithm is an improvement to the TCP protocol fast retransmission algorithm. Although it can reduce the number of times a TCP entity sends duplicate packets, it cannot be avoided. Moreover, if the data packet is lost again, the data packet is retransmitted again. The real-time performance is poor.

In summary, these methods inevitably bring about the waste of air interface bandwidth resources, and may also introduce other problems such as poor real-time performance. Summary of the invention

The embodiments of the present invention provide a method and a device for retransmitting a TCP data on a wireless side. In the prior art solution, in a system in which a TCP connection is established across a wireless network, the wireless side retransmission processing cannot be reasonably solved, and the system resources are wasted. .

To achieve the above objective, an embodiment of the present invention provides a method for retransmitting a wireless side TCP data, including at least the following steps: When a TCP entity receives an uplink message sent by a terminal device, the TCP entity determines the uplink. Whether the Dup ACK message is included in the message; if yes, the TCP entity determines whether the RLC layer has sent all the fragment packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the terminal device The acknowledgment message returned; if the judgment result is yes, the TCP entity counts and accumulates the Dup ACK message; the TCP entity determines whether the current count value of the Dup ACK message reaches 2; The data packet corresponding to the Dup ACK message is transmitted, and the count value of the Dup ACK message is set to zero.

Preferably, the TCP entity determines whether the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the acknowledgement message returned by the terminal device, including: The TCP entity determines a sequence number of the fragment packet that has been confirmed by the terminal device in each fragment packet of the data packet corresponding to the Dup ACK message; and the TCP entity determines whether the maximum value of the sequence number reaches the Determining the sequence number of the data packet corresponding to the Dup ACK message at the RLC layer; if so, the TCP entity confirms that the RLC layer has already performed the Dup ACK All the fragmented packets of the data packet corresponding to the message are sent to the terminal device, and an acknowledgement message returned by the terminal device is received.

Preferably, after the TCP entity determines whether the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and after receiving the acknowledgement message returned by the terminal device, The method includes: if the judgment result is no, the TCP entity sets the count value of the Dup ACK message to zero.

Preferably, in the process of retransmitting the data packet corresponding to the Dup ACK message, the TCP entity further includes: the TCP entity records a termination sequence number of the data packet that is retransmitted at the RLC layer.

Preferably, after the TCP entity determines that the uplink message does not include a Dup ACK message, or the TCP entity retransmits the data packet corresponding to the Dup ACK message, the method further includes: the TCP entity determining the uplink Whether the SACK message is included in the message; if yes, the TCP entity selects a corresponding data packet according to the sending sequence of each data packet corresponding to the SACK message; the TCP entity determines whether the RLC layer has already selected the currently selected data. All the fragmented packets of the packet are sent to the terminal device, and an acknowledgement message returned by the terminal device is received; if the determination result is yes, the TCP entity retransmits the currently selected data packet.

Preferably, the TCP entity determines whether the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, and receives the acknowledgement message returned by the terminal device, including: a sequence number of a fragment packet that has been confirmed by the terminal device in each fragment packet of the currently selected data packet; the TCP entity determining whether the maximum value of the sequence number reaches the currently selected data a termination sequence number of the RLC layer; if so, the TCP entity confirms that the RLC layer has sent all the fragment packets of the currently selected data packet to the terminal device, and receives the return from the terminal device Confirm the message.

Preferably, the TCP entity determines whether the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, and after receiving the acknowledgement message returned by the terminal device, the method further includes: If not, the TCP entity confirms that each data packet corresponding to the SACK message after the currently selected data packet is not sent.

Preferably, in the process of retransmitting the currently selected data packet, the TCP entity further includes: the TCP entity records a termination sequence number of the data packet that is retransmitted at the RLC layer. On the other hand, the embodiment of the present invention further provides a network device, as a TCP entity, is applied to a network system that has a TCP connection across a wireless network, and includes: a receiving module, configured to receive an uplink message sent by the terminal device; a determining module, configured to determine whether the uplink message received by the receiving module includes a Dup ACK message, and the second determining module is configured to determine whether the RLC layer is already included when the determining result of the first determining module is included Sending, to the terminal device, all the fragmented packets of the data packet corresponding to the Dup ACK message, and receiving an acknowledgement message returned by the terminal device; and the counting module configured to be determined by the second determining module If yes, the Dup ACK message received by the receiving module is counted and accumulated; the third determining module is configured to determine whether the current count value of the Dup ACK message counted by the counting module reaches 2; processing module, configuration Retransmitting the data corresponding to the Dup ACK message when the judgment result of the third determining module is reached. , And notifies the module counts the count value to zero Dup ACK message.

Preferably, the second determining module is configured to: determine a sequence number of a fragment packet that has been confirmed by the terminal device in each fragment packet of the data packet corresponding to the Dup ACK message; determine the sequence Whether the maximum value of the number reaches the termination sequence number of the data packet corresponding to the Dup ACK message at the RLC layer; if so, it is confirmed that the RLC layer has sent all the fragment packets of the data packet corresponding to the Dup ACK message to the The terminal device is received, and an acknowledgement message returned by the terminal device is received.

Preferably, the counting module is further configured to: when the determination result of the second determining module is negative, set the count value of the Dup ACK message to zero.

Preferably, the processing module is further configured to: when retransmitting the data packet corresponding to the Dup ACK message, record a termination sequence number of the data packet that is retransmitted at the RLC layer.

Preferably, the fourth determining module, the selecting module, and the fifth determining module are configured to: the fourth determining module is configured to determine, in the first determining module, that the uplink message does not include a Dup ACK message, or After the processing module retransmits the data packet corresponding to the Dup ACK message, it is determined whether the uplink message includes a SACK message, and the selecting module is configured to: when the determination result of the fourth determining module is included, The sending sequence of each data packet corresponding to the SACK message selects a corresponding data packet; the fifth determining module is configured to determine whether the RLC layer has been Sending, by the processing module, all the fragmented packets of the data packet currently selected by the selection module to the terminal device, and receiving the confirmation message returned by the terminal device; When the judgment result of the module is YES, the currently selected data packet is retransmitted.

Preferably, the fifth determining module is configured to: determine, in each fragment packet of the data packet currently selected by the selecting module, a sequence number of the fragment packet that has been confirmed by the terminal device; determine the sequence Whether the maximum value of the number reaches the termination sequence number of the currently selected data packet at the RLC layer; if so, confirming that the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, And receiving the confirmation message returned by the terminal device.

Preferably, the processing module is further configured to: when the determination result of the fifth determining module is negative, confirm that each data packet corresponding to the SACK message after the data packet currently selected by the selecting module is Not sent.

Preferably, the processing module is further configured to: when retransmitting the data packet currently selected by the selecting module, record a termination sequence number of the data packet that is retransmitted at the RLC layer.

Compared with the prior art, the technical solution proposed by the embodiment of the present invention has the following advantages: In the case that the TCP entity receives the uplink message including the Dup ACK message sent by the terminal device, by applying the technical solution of the embodiment of the present invention, If the TCP entity determines that the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the acknowledgement message returned by the terminal device, the Dup ACK message is counted and accumulated, and is counted. When the value reaches 2, the data packet corresponding to the Dup ACK message is retransmitted, so that the characteristics of the local buffering and retransmission of the TCP entity data can be flexibly utilized, and the Dup ACK of the terminal device is distinguished according to the characteristics of the reliable transmission of the RLC. To achieve fast retransmission of TCP layer data, accurately determine whether the data packet needs TCP layer retransmission on the wireless side of the TCP proxy, improve TCP performance and air interface resource utilization, and avoid unnecessary data retransmission. The system resources are wasted. DRAWINGS

FIG. 1 is a schematic flowchart of a method for wireless side TCP data retransmission according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a method for retransmitting wireless side TCP data according to an embodiment of the present invention; Schematic diagram of a SACK message for performing packet retransmission processing;

FIG. 3 is a schematic flowchart of a method for retransmitting wireless side TCP data in a specific scenario according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a network device according to an embodiment of the present invention. detailed description

As described in the background art, TCP is a reliable transmission protocol researched and developed for the wired network Internet. The transmission characteristics of the wired network are low bit error rate and easy congestion. Therefore, its transmission control algorithm is mainly designed based on the network congestion model.

However, when a TCP connection spans both wired and wireless networks, TCP will not be able to adapt to the high bit error rate, high latency jitter, cell handover, out-of-order, etc. of the wireless transmission channel, causing false slow start and congestion avoidance. And retransmission, when the quality of the air interface is quickly restored, TCP data cannot be transmitted in time, resulting in a decrease in bandwidth resource utilization, a decrease in effective bandwidth, and fluctuations in throughput.

In order to improve the transmission performance of the TCP connection across the wireless network, a common practice in the prior art is to set a TCP proxy on the RNC side, and enhance the wireless side through mechanisms such as local buffering, sorting, flow control, local retransmission, and suppression of Dup ACK. The performance of the transmission.

However, in a wireless environment, due to large changes in the air interface environment, many out-of-order packets are caused. The retransmission of these packets can be solved in the RLC. If retransmitted at the TCP layer, it will cause unnecessary waste of air interface resources.

In order to overcome such a defect, the embodiment of the present invention provides a method for wireless side TCP data retransmission, which mainly solves how to determine whether a data packet needs a TCP layer retransmission in a wireless side of a TCP proxy, so as to improve TCP performance and air interface. Resource utilization issues.

As shown in FIG. 1 , it is a schematic flowchart of a method for retransmitting a wireless side TCP data according to an embodiment of the present invention, where the method specifically includes the following steps:

Step S101: When the TCP entity receives the uplink message sent by the terminal device, the TCP entity determines whether the uplink message includes a Dup ACK message.

If yes, step S102 is performed;

If not, use other methods according to the preset rules (for example, according to SACK message or The other information is processed and processed accordingly. The specific processing manner is described in the following description, and details are not described herein again.

Step S102: The TCP entity determines whether the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives an acknowledgement message returned by the terminal device.

If the result of the determination is yes, it indicates that the corresponding data packet has been sent in the RLC layer, but the terminal device side does not receive the data correctly. The corresponding retransmission processing may be performed, and the subsequent process needs to be determined. Therefore, step S103 is performed. ;

If the judgment result is no, it indicates that the corresponding data packet has not been sent yet in the RLC layer, or, although the RLC has been sent, but has not received the correct reception confirmation message returned by the terminal device side, the corresponding Dup ACK message. The proposed retransmission request may be resolved as the data packet is sent and received by the terminal device. Therefore, the corresponding retransmission process may be temporarily performed. In this embodiment, the TCP entity further performs step S106.

In the actual application scenario, the processing of this step specifically includes:

(1) The TCP entity determines a sequence number of a fragment packet that has been confirmed by the terminal device in each fragment packet of the data packet corresponding to the Dup ACK message.

(2) The TCP entity determines whether the maximum value of the sequence number reaches the termination sequence number of the data packet corresponding to the Dup ACK message at the RLC layer.

If yes, the TCP entity confirms that the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives an acknowledgement message returned by the terminal device.

Conversely, if it is not reached, it means that the corresponding data packet has not been sent yet in the RLC layer, or, although the RLC has already sent, it has not received the confirmation message of correct reception returned by the terminal device side.

Step S103: The TCP entity counts and accumulates the Dup ACK message.

Step S104: The TCP entity determines whether the current count value of the Dup ACK message reaches 2.

If yes, proceed to step S105; If not, it indicates that the TCP entity does not need to perform retransmission processing for the data packet corresponding to the Dup ACK message, and returns to step S101.

It should be noted that, in this embodiment, the idea that the count value of the Dup ACK message is equal to 2 is used as a trigger condition for data packet retransmission is:

In the uplink data, the ACK message (including the Dup ACK message) and the RLC layer acknowledgment data (including the correct received acknowledgment message sent after the terminal device side receives the fragment packet in the data packet) are often in the same FP (Frame) In the Protocol, frame protocol, for this reason, if the count value of the Dup ACK message is set to 1 to trigger the packet retransmission, a large probability of repeated multiple transmission occurs. However, if the count value of the Dup ACK message is equal to 2, the data packet retransmission is triggered, indicating that the RLC layer has sent the data packet to the terminal device side and receives the terminal device when the Dup ACK message is received last time. Side confirmation.

Step S105: The TCP entity retransmits the data packet corresponding to the Dup ACK message, and sets the count value of the Dup ACK message to zero.

In an actual application scenario, in the process of performing data packet retransmission, the TCP entity also needs to record the termination sequence number of the data packet that is retransmitted in the RLC layer, so as to use the termination sequence number as a subsequent processing. In the process, it is judged whether or not the data packet is retransmitted.

Through such processing, the retransmission processing of the data packet corresponding to the Dup ACK message is completed. After the execution of this step is completed, the process proceeds to step S106.

Step S106: The TCP entity sets the count value of the Dup ACK message to zero.

After the count value of the Dup ACK message is set to zero, a new counting process can be started for the Dup ACK message to determine to perform a new retransmission process.

It should be further noted that the TCP entity performs the process of retransmitting the data packet according to the Dup ACK message. On this basis, the TCP entity may also use other methods according to the preset rule (for example, processing according to the SACK message or other information). The subsequent processing is continued, and the specific processing manner is described in the following description, and details are not described herein again.

It should be noted that, in the step S101, the result of the determination is no, and after the step S106 is completed, the process in which the TCP entity processes in other manners according to the preset rule is mentioned. In the actual application, the preset rule corresponds to Processing can include multiple types, where The comprehensiveness and accuracy of the packet retransmission process can be handled in accordance with the SACK message. Specifically, when the TCP entity determines in step S101 that the uplink message does not include Dup

After the ACK message, or the TCP entity retransmits the data packet corresponding to the Dup ACK message in step S105, the following process includes performing the data packet retransmission process according to the SACK message, and the process flow diagram of the process is shown in FIG. 2. As shown, the following steps are specifically included:

Step S201: The TCP entity determines whether the uplink message received by itself is included in the uplink message.

SACK message.

If yes, step S202 is performed;

If not, perform other processing or directly stop the current packet retransmission process. Step S202: The TCP entity selects a corresponding data packet according to a sending sequence of each data packet corresponding to the SACK message.

Step S203: The TCP entity determines whether the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, and receives the acknowledgement message returned by the terminal device.

If the result of the determination is yes, step S204 is performed;

If the result of the determination is no, step S205 is performed.

Similar to the foregoing step S102, the process of determining in this step is specifically as follows: the TCP entity determines, among the fragment packets of the currently selected data packet, the fragment packet that has been confirmed by the terminal device. serial number.

The TCP entity determines whether the maximum value of the sequence number reaches the termination sequence number of the currently selected data packet at the RLC layer.

If so, the TCP entity confirms that the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, and receives an acknowledgement message returned by the terminal device.

Step S204: The TCP entity retransmits the currently selected data packet.

Step S205, the TCP entity confirms the SACK after the currently selected data packet Each packet corresponding to the message has not been sent.

Through this step, the transmission status of subsequent data packets can be quickly determined, and the system resources and processing time caused by separately determining each data packet corresponding to the SACK message can be avoided, and the corresponding processing efficiency is improved.

It should be noted that the foregoing process of processing according to the SACK message may perform more comprehensive processing on the information returned by the terminal device on the basis of the foregoing retransmission process according to the Dup ACK message, thereby determining whether the data is more accurately determined. Retransmit the corresponding data packet.

Compared with the prior art, the technical solution proposed by the embodiment of the present invention has the following advantages: In the case that the TCP entity receives the uplink message including the Dup ACK message sent by the terminal device, by applying the technical solution of the embodiment of the present invention, If the TCP entity determines that the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the acknowledgement message returned by the terminal device, the Dup ACK message is counted and accumulated, and is counted. When the value reaches 2, the data packet corresponding to the Dup ACK message is retransmitted, so that the characteristics of the local buffering and retransmission of the TCP entity data can be flexibly utilized, and the Dup ACK of the terminal device is distinguished according to the characteristics of the reliable transmission of the RLC. To achieve fast retransmission of TCP layer data, accurately determine whether the data packet needs TCP layer retransmission on the wireless side of the TCP proxy, improve TCP performance and air interface resource utilization, and avoid unnecessary data retransmission. The system resources are wasted. The technical solutions proposed by the embodiments of the present invention are described below in conjunction with specific application scenarios.

The technical solution proposed by the embodiment of the present invention is a feature of flexibly utilizing local buffering and retransmission of TCP entity data, and combining the characteristics of reliable transmission of RLC (Radio Link Layer) to perform Dup ACK message sent by the terminal device side. Screening to achieve fast retransmission of TCP layer data.

FIG. 3 is a schematic flowchart of a method for retransmitting a wireless side TCP data in a specific application scenario according to an embodiment of the present disclosure, where the method specifically includes the following steps:

Step S301: The TCP entity performs normal data packet transmission at the RLC layer.

In this process, the TCP entity records the sequence number of the last fragment packet of each packet at the RLC layer, that is, the aforementioned termination sequence number. In the actual application scenario, the processing of this step is actually:

The TCP layer sends the data packet to the RLC layer, and the RLC segments the data packet into a plurality of fragment packets, and records the sequence number (EndSn, that is, the foregoing termination sequence number) of the last fragment packet at the TCP layer.

Step S302: The TCP entity receives an ACK message sent by the terminal device, and determines whether it is Dup.

ACK message.

If the result of the determination is yes, step S303 is performed;

If the result of the determination is no, step S308 is performed.

Step S303: The TCP entity determines an EndSn of the data packet that needs to be retransmitted corresponding to the Dup ACK message, and a fragment packet sequence number AckSn of the data packet that has been confirmed by the terminal device received by the RLC layer.

Step S304: The TCP entity compares the determined maximum AckSn and EndSn.

If the AckSn is greater than or equal to EndSn, step S305 is performed;

If the AckSn is smaller than the EndSn, it indicates that the TCP entity does not need to perform retransmission processing for the data packet corresponding to the Dup ACK message, and the processing of the Dup ACK message in the received ACK message ends, and the steps may be performed. S308 performs SACK processing or performs other processing, and in Fig. 3, it indicates that other processing is performed.

Step S305: The TCP entity adds 1 to the Dup Ack variable corresponding to the Dup Ack message. Step S306: The TCP entity determines whether the Dup Ack variable is equal to 2.

If yes, step S307 is performed;

If not, it indicates that the TCP entity does not need to perform retransmission processing for the data packet corresponding to the Dup ACK message, and the processing of the Dup ACK message in the received ACK message ends, and the SACK may be performed in step S308. Processing or other processing is shown in Fig. 3 as performing other processing.

Step S307: The TCP entity retransmits the data packet to the RLC layer, and records the Sn of the last fragment packet of the newly transmitted data packet to update the EndSn of the data packet, and simultaneously clears the Dup Ack variable.

After the completion of this step, in order to achieve more accurate and comprehensive data retransmission processing, you can enter Step S308 is performed in one step.

Step S308: The TCP entity determines whether a SACK message is currently received.

If yes, step S309 is performed to perform a corresponding SACK processing flow;

If not, it indicates that the TCP entity does not need to retransmit the corresponding data packet according to the SACK message. In the actual application scenario, other processing may be performed in this case.

Step S309: The TCP entity selects a corresponding data packet according to the sending sequence of each data packet corresponding to the SACK message.

Step S310: The TCP entity determines the EndSn of the data packet, and the fragment packet sequence number AckSn of the data packet that has been confirmed by the terminal device received by the RLC layer.

Step S311: The TCP entity compares the determined maximum AckSn with the EndSn of the data packet.

If the AckSn is greater than or equal to EndSn, step S312 is performed;

If the AckSn is smaller than EndSn, step S314 is performed.

Step S312: The TCP entity retransmits the data packet.

After the execution of this step is completed, the process proceeds to step S313.

Step S313: The TCP entity determines whether all the data packets that need to be retransmitted corresponding to the SACK message are selected.

If the result of the determination is no, then return to step S309;

If the result of the determination is yes, then other processing is performed.

Step S314: The TCP entity confirms that each data packet corresponding to the SACK message after the currently selected data packet has not been sent.

After this step is completed, other processing is directly performed.

Through this step, the sending status of the subsequent data packet can be quickly determined, and the system resource and processing time consumption caused by separately determining each data packet corresponding to the SACK message can be avoided, and the corresponding processing efficiency is improved. It should be noted that, in an actual application scenario, other processes mentioned in the foregoing steps may include:

Returning to step S302, it continues to wait for the subsequent ACK message, or performs other processing operations according to the preset processing rule, and the change of the specific content of the other processing does not affect the protection scope of the present invention.

Compared with the prior art, the technical solution proposed by the embodiment of the present invention has the following advantages: In the case that the TCP entity receives the uplink message including the Dup ACK message sent by the terminal device, by applying the technical solution of the embodiment of the present invention, If the TCP entity determines that the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the acknowledgement message returned by the terminal device, the Dup ACK message is counted and accumulated, and is counted. When the value reaches 2, the data packet corresponding to the Dup ACK message is retransmitted, so that the characteristics of the local buffering and retransmission of the TCP entity data can be flexibly utilized, and the Dup ACK of the terminal device is distinguished according to the characteristics of the reliable transmission of the RLC. To achieve fast retransmission of TCP layer data, accurately determine whether the data packet needs TCP layer retransmission on the wireless side of the TCP proxy, improve TCP performance and air interface resource utilization, and avoid unnecessary data retransmission. The system resources are wasted. In order to implement the technical solution of the embodiment of the present invention, the embodiment of the present invention further provides a network device, which is used as a TCP entity in a network system that has a TCP connection across a wireless network, and a schematic structural diagram thereof is shown in FIG. 4, which includes at least :

The receiving module 41 is configured to receive an uplink message sent by the terminal device.

The first determining module 42 is configured to determine whether the uplink message received by the receiving module 41 includes a Dup ACK message;

The second judging module 43 is configured to: when the judgment result of the first judging module 42 is included, determine whether the RLC layer has sent all the fragment packets of the data packet corresponding to the Dup ACK message to the terminal device. Receiving an acknowledgement message returned by the terminal device;

The counting module 44 is configured to count and accumulate the Dup ACK message received by the receiving module 41 when the determination result of the second determining module 43 is YES;

The third determining module 45 is configured to determine whether the current count value of the Dup ACK message counted by the counting module 44 reaches 2; The processing module 46 is configured to retransmit the data packet corresponding to the Dup ACK message when the determination result of the third determining module 45 is reached, and notify the counting module 44 to count the Dup ACK message. Zero.

The second determining module 43 is specifically configured as:

Determining, in each fragment packet of the data packet corresponding to the Dup ACK message, a sequence number of the fragment packet that has been confirmed by the terminal device;

Determining whether the maximum value of the sequence number reaches the termination sequence number of the data packet corresponding to the Dup ACK message at the RLC layer;

If yes, it is confirmed that the RLC layer has sent all the fragment packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the acknowledgement message returned by the terminal device.

Further, the counting module 44 is further configured to set the count value of the Dup ACK message to zero when the determination result of the second determining module 43 is negative.

It should be noted that, the processing module 46 is further configured to record, in the process of retransmitting the data packet corresponding to the Dup ACK message, the termination sequence number of the data packet that is retransmitted at the RLC layer.

In another aspect, the network device further includes a fourth determining module 47, a selecting module 48, and a fifth determining module 49, wherein:

The fourth determining module 47 is configured to: after the first determining module 42 determines that the uplink message does not include a Dup ACK message, or the processing module 46 retransmits the data packet corresponding to the Dup ACK message, Determining whether the uplink message includes a SACK message;

The selecting module 48 is configured to select a corresponding data packet according to a sending sequence of each data packet corresponding to the SACK message when the determining result of the fourth determining module 47 is included; the fifth determining module 49. The method is configured to determine whether the RLC layer has sent all the fragmented packets of the data packet currently selected by the selecting module 48 to the terminal device, and receives an acknowledgement message returned by the terminal device.

The processing module 46 is further configured to retransmit the currently selected data packet when the determination result of the fifth determining module 49 is YES.

The fifth determining module 49 is specifically configured as:

Determining, in each fragment packet of the currently selected data packet of the selection module 48, The serial number of the fragment packet confirmed by the end device;

Determining whether the maximum value of the serial number reaches the termination sequence number of the currently selected data packet at the RLC layer;

If so, it is confirmed that the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, and receives an acknowledgement message returned by the terminal device.

Further, the processing module 46 is further configured to: when the determination result of the fifth determining module 49 is negative, confirm each data corresponding to the SACK message after the data packet currently selected by the selecting module 48 None of the packages have been sent.

In an actual application scenario, the processing module 46 is further configured to record, in the process of retransmitting the data packet currently selected by the selecting module 48, the termination sequence number of the data packet that is retransmitted in the RLC layer. .

Compared with the prior art, the technical solution proposed by the embodiment of the present invention has the following advantages: In the case that the TCP entity receives the uplink message including the Dup ACK message sent by the terminal device, by applying the technical solution of the embodiment of the present invention, If the TCP entity determines that the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the acknowledgement message returned by the terminal device, the Dup ACK message is counted and accumulated, and is counted. When the value reaches 2, the data packet corresponding to the Dup ACK message is retransmitted, so that the characteristics of the local buffering and retransmission of the TCP entity data can be flexibly utilized, and the Dup ACK of the terminal device is distinguished according to the characteristics of the reliable transmission of the RLC. To achieve fast retransmission of TCP layer data, accurately determine whether the data packet needs TCP layer retransmission on the wireless side of the TCP proxy, improve TCP performance and air interface resource utilization, and avoid unnecessary data retransmission. The system resources are wasted. Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments of the present invention may be implemented by hardware, or may be implemented by means of software plus a necessary general hardware platform. Based on the understanding, the technical solution of the embodiment of the present invention may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (which may be a CD-ROM, a USB flash drive, a mobile hard disk, etc.). Including a plurality of instructions for causing a computer device (which may be a personal computer, a server, or a network side device, etc.) to perform the various implementation scenarios of the embodiments of the present invention. Methods.

A person skilled in the art can understand that the drawings are only a schematic diagram of a preferred implementation scenario, and the modules or processes in the drawings are not necessarily required to implement the embodiments of the present invention.

Those skilled in the art can understand that the modules in the apparatus in the implementation scenario may be distributed in the apparatus for implementing the scenario according to the implementation scenario description, or may be correspondingly changed in one or more devices different from the implementation scenario. The modules of the above implementation scenarios may be combined into one module, or may be further split into multiple sub-modules.

The serial numbers of the foregoing embodiments of the present invention are merely for description, and do not represent the advantages and disadvantages of the implementation scenarios. The examples are not limited thereto, and any changes that can be made by those skilled in the art should fall within the scope of the business restrictions of the embodiments of the present invention.

Claims

Claim

A method for wireless side TCP data retransmission, comprising the following steps:

When the TCP entity receives the uplink message sent by the terminal device, the TCP entity determines whether the uplink message includes a Dup ACK message;

If yes, the TCP entity determines whether the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives an acknowledgement message returned by the terminal device;

If the judgment result is yes, the TCP entity counts and accumulates the Dup ACK message;

The TCP entity determines whether the current count value of the Dup ACK message reaches 2;

If so, the TCP entity retransmits the data packet corresponding to the Dup ACK message, and sets the count value of the Dup ACK message to zero.

The method of claim 1, wherein the TCP entity determines whether the RLC layer has sent all the fragment packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the The confirmation message returned by the terminal device includes:

Determining, by the TCP entity, a sequence number of a fragment packet that has been confirmed by the terminal device in each fragment packet of the data packet corresponding to the Dup ACK message;

Determining, by the TCP entity, whether the maximum value of the sequence number reaches a data packet corresponding to the Dup ACK message.

The termination sequence number of the RLC layer;

The method of claim 1, wherein the TCP entity determines whether the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives the After the confirmation message returned by the terminal device, the method further includes:

If the result of the determination is no, the TCP entity sets the count value of the Dup ACK message to zero.

The method of claim 1, wherein the process of retransmitting the data packet corresponding to the Dup ACK message by the TCP entity further includes:

The TCP entity records the termination sequence number of the data packet for retransmission at the RLC layer.

The method according to claim 1, wherein, after the TCP entity determines that the uplink message does not include a Dup ACK message, or the TCP entity retransmits the data packet corresponding to the Dup ACK message, Includes:

Determining, by the TCP entity, whether the uplink message includes a SACK message; If yes, the TCP entity selects a corresponding data packet according to a sending sequence of each data packet corresponding to the SACK message;

Determining, by the TCP entity, whether the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, and receiving an acknowledgement message returned by the terminal device;

If the result of the determination is yes, the TCP entity retransmits the currently selected data packet.

The method according to claim 5, wherein the TCP entity determines whether the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, and receives the returned by the terminal device. The confirmation message includes:

Determining, by the TCP entity, a sequence number of a fragment packet that has been confirmed by the terminal device in each fragment packet of the currently selected data packet;

Determining, by the TCP entity, whether a maximum value of the sequence number reaches a termination sequence number of the currently selected data packet at an RLC layer;

The method according to claim 5, wherein the TCP entity determines whether the RLC layer has sent all the fragmented packets of the currently selected data packet to the terminal device, and receives the returned by the terminal device. After confirming the message, it also includes:

If the judgment result is no, the TCP entity confirms that each data packet corresponding to the SACK message after the currently selected data packet has not been transmitted.

The method of claim 5, wherein the process of retransmitting the currently selected data packet by the TCP entity further includes:

A network device, as a TCP entity, is applied to a network system that has a TCP connection across a wireless network, where the network device includes:

a receiving module, configured to receive an uplink message sent by the terminal device;

The first determining module is configured to determine whether the uplink message received by the receiving module includes a Dup ACK message; The second judging module is configured to: when the judgment result of the first judging module is included, determine whether the RLC layer has sent all the fragment packets of the data packet corresponding to the Dup ACK message to the terminal device, and Receiving an acknowledgement message returned by the terminal device;

a counting module configured to count and accumulate Dup ACK messages received by the receiving module when the determining result of the second determining module is YES;

a third determining module, configured to determine whether the current count value of the Dup ACK message counted by the counting module reaches 2;

The processing module is configured to retransmit the data packet corresponding to the Dup ACK message when the determination result of the third determining module is reached, and notify the counting module to set the count value of the Dup ACK message to zero.

The network device according to claim 9, wherein the second determining module is configured to:

If yes, it is confirmed that the RLC layer has sent all the fragmented packets of the data packet corresponding to the Dup ACK message to the terminal device, and receives an acknowledgement message returned by the terminal device.

The network device according to claim 9, wherein the counting module is further configured to: when the determination result of the second determining module is negative, set the count value of the Dup ACK message to zero.

The network device according to claim 9, wherein the processing module is further configured to:

In the process of retransmitting the data packet corresponding to the Dup ACK message, the termination sequence number of the data packet to be retransmitted at the RLC layer is recorded.

The network device according to claim 9, further comprising a fourth determining module, a selecting module, and a fifth determining module;

among them,

The fourth determining module is configured to determine, after the first determining module determines that the uplink message does not include a Dup ACK message, or after the processing module retransmits the data packet corresponding to the Dup ACK message, Whether the SACK message is included in the uplink message;

The selecting module is configured to: when the determination result of the fourth determining module is included, according to the SACK Select the corresponding data packet in the order in which the packets correspond to each other;

The fifth determining module is configured to determine whether the RLC layer has sent all the fragmented packets of the data packet currently selected by the selecting module to the terminal device, and receives an acknowledgement message returned by the terminal device;

The processing module is further configured to retransmit the currently selected data packet when the determination result of the fifth determining module is YES.

The network device according to claim 13, wherein the fifth determining module is configured to:

Determining, in each fragment packet of the data packet currently selected by the selection module, a sequence number of the fragment packet that has been confirmed by the terminal device;

Determining whether the maximum value of the sequence number reaches the termination sequence number of the currently selected data packet at the RLC layer; if so, confirming that the RLC layer has sent all the fragment packets of the currently selected data packet to the The terminal device is received, and an acknowledgement message returned by the terminal device is received.

The network device according to claim 13, wherein the processing module is further configured to:

When the determination result of the fifth determining module is negative, it is confirmed that each data packet corresponding to the SACK message after the data packet currently selected by the selecting module is not transmitted.

In the process of retransmitting the data packet currently selected by the selection module, the termination sequence number of the data packet to be retransmitted at the RLC layer is recorded.