CN104683070A - Transmission control method based on random linear network coding - Google Patents

Abstract

The invention discloses a transmission control method based on random linear network coding and mainly solves the problems of large time delay of a transmission control protocol (TCP) under a high-bit error rate link and decrease of throughput. The transmission control method comprises the following realization steps: (1) adding network coding (NC) layers between a transmission control protocol layer and an internet protocol (IP) layer which are respectively at the transmitting end and the receiving end; (2) performing grouping random linear network coding on data packets of the transmission control protocol through the network coding layer at the transmitting end and transmitting to the internet protocol layer at the local end; (3) receiving the coded data packets from the internet protocol layer at the local end through the network coding layer at the receiving end, wherein the data packets are subjected to response and grouping decoding in sequence and are submitted to the transmission control protocol layer. According to the transmission control method, the network throughout capacity under the high-bit error rate link is effectively improved, and the effect of round-trip delay of the link on the transmission control protocol performance is reduced.

Description

Based on the transfer control method of random linear network encoding

Technical field

The invention belongs to Transmitting of Multi-media Information field, the transmission control protocol TCP of particularly a kind of improvement, under being used in high bit-error link, improve the throughput of network.

Background technology

TCP is a kind of connection-oriented, provides the transport layer communication protocol that reliable byte stream is served.It can ensure the correct transmission of data, and has very high throughput in the reliable situation of link, is therefore widely used in the transmission of the network data such as file transfer protocol (FTP) FTP, HTML (Hypertext Markup Language) HTTP.But because TCP has the controlling mechanism of network data flow, its application in high bit-error network is restricted.The network data flow-control mechanism of TCP mainly comprises flow control and congestion control.Flow control refers to and controls between the data transmission interval of transmitting terminal by sliding window, prevents the loss of data because transmission rate and receiving velocity do not mate and cause; Congestion control refers to that TCP connects according to network congestion degree dynamic conditioning Internet resources, prevents from causing network link to transship in multiple data stream injection network.Wherein, network congestion refers in network that there is excessive packet makes intermediate node router store spilling, produces information dropout and causes network performance to reduce.When TCP detects that network occurs congested, data package transmission velocity will be reduced to reduce rapidly the throughput in network by flow control and congestion control mechanism.If but TCP is applied in high bit-error network, once there is packet loss in network, congested situation will be there is and process in TCP according to network, cause network throughput sharply to decline, and the throughput that as far as possible should strengthen the transmission rate ability keeping system of transmitting terminal when Network Packet Loss maintain in higher level.Therefore the application of TCP in the high bit-error networks such as wireless network is restricted.

Summary of the invention

The object of the invention is to the problem for above existing transmission control protocol TCP, a kind of transfer control method based on random linear network encoding is proposed, with under there is congested or packet drop at network without the need to retransmitting the packet of appointed sequence number, the transmission rate of packet under increase high bit-error, effectively improves the throughput in high bit-error lower network.

Technical scheme of the present invention is achieved in that

Network code theoretical foundation is pointed out, node in network is by carrying out Code And Decode operation to the information of transmission, effectively can shorten the time required for information transmission, reduce the number of times that node sends data, thus realize improving network throughput and the object reducing energy consumption.Based on this thought, the present invention utilizes random linear network encoding to improve TCP, can be applicable in the higher network of the error rate.Its technical thought is that the network packet by having divided into groups to TCP splits, random linear network encoding and the mode such as to re-assembly, and realizes the transfer of data of TCP under congested or packet drop occur network.

According to above-mentioned thinking, technical step of the present invention comprises as follows:

(1) between the transmission control protocol TCP layer and Internet protocol IP layer of transmitting terminal and receiving terminal, network code NC layer is added;

(2) the network code NC layer of transmitting terminal carries out grouping random linear network encoding to the packet of transmission control protocol TCP, and is sent to the Internet protocol IP layer of local terminal;

(3) the network code NC layer of receiving terminal receives encoded packet from the Internet protocol IP layer of local terminal, replys successively and packet decoding, and submit to transmission control protocol TCP layer to these packets.

The present invention compared with prior art has the following advantages:

1, the present invention is owing to carrying out random linear network encoding to transmission control protocol TCP packet, and thus complexity is low, and coding rate is fast.

2, the present invention is owing to replying accordingly according to the dissimilar of transmission control protocol TCP packet, enables receiving terminal receive enough encoded packets, without the need to the packet loss process in channel, effectively improves the throughput in high bit-error link lower network.

3, the present invention carries out packet decoding due to the coded data packet received receiving terminal, and its complexity is low, and decoding speed is fast, and accuracy is high.

Accompanying drawing explanation

Fig. 1 is realization flow figure of the present invention.

Fig. 2 is the random linear network encoding schematic diagram in the present invention.

Fig. 3 is the response schematic diagram in the present invention.

Fig. 4 is the decoding schematic diagram in the present invention.

Fig. 5 is the throughput of the present invention and transmission control protocol TCP and the graph of a relation of the error rate under single-hop networks scene.

Fig. 6 is the throughput of the present invention and transmission control protocol TCP and the graph of a relation of the error rate under multihop network scene.

Embodiment

Describe the present invention referring to accompanying drawing:

With reference to Fig. 1, the present invention is based on the transfer control method of random linear network encoding, comprise the following steps:

Step 1: add network code NC layer between the transmission control protocol TCP layer and Internet protocol IP layer of transmitting terminal and receiving terminal.

Step 2: the network code NC layer of transmitting terminal carries out grouping random linear network encoding to the packet of transmission control protocol TCP, and be sent to the Internet protocol IP layer of local terminal.

With reference to Fig. 2, being implemented as follows of this step:

2a) packet of transmission control protocol TCP layer arrival network code NC layer is carried out buffer memory by transmitting terminal, and when the packet number of buffer area reaches N, then these N number of data are set to a grouping, N is the number of prespecified order;

2b) take out the original tcp data handbag head in above-mentioned grouping, and buffer memory;

2c) transmitting terminal produces coding core, and namely length is a random vector of N, each value stochastic generation in galois field in this random vector;

2d) under galois field, the n-th random number in this random vector is multiplied with the n-th packet in this above-mentioned grouping, and the results added that will obtain, wherein n≤N;

2e) using core and the 2d of encoding) in the result of calculation that obtains repack as data, and add 2b successively) in the TCP head of institute buffer memory, be sent to the Internet protocol IP layer of local terminal together, turn back to step 2a), until all data are encoded.

Step 3: the network code NC layer of receiving terminal receives encoded packet from the Internet protocol IP layer of local terminal, replys successively and packet decoding, and submit to transmission control protocol TCP layer to these packets.

3a) encoded packet is replied:

With reference to Fig. 3, being implemented as follows of this step:

3a1) receiving terminal is by the encoded packets that receives stored in decoding buffer area, and judges the decoding bag grouping whether this encoded packets belongs to current decode pointer and point to:

If newly arrived encoded packets belongs to the decoding bag grouping pointed by current decode pointer, then check whether the number of this block encoding bag is N, if N then decodes, and host-host protocol TCP layer is submitted in the grouping of successfully decoded, perform step 3a2);

If newly arrived encoded packets does not belong to the decoding bag grouping pointed by current decode pointer, then perform step 3a4);

Described decode pointer, refers to the integer pointing to the current encoded packets grouping not having to decode;

3a2) decode pointer is pointed to the grouping of next decoding bag, and whether the number of packet is N in judging the grouping that decode pointer points to, if N, then continue decode pointer to be pointed to the grouping of next decoding bag, until the decoding package pointed by it is not N, perform step 3a3);

3a3) receiving terminal sends to transmitting terminal and retransmits the information of encoded packets, wherein needs the number that retransmits for the number of packet in N deducts pointed by current decode pointer decoding package;

3a4) open up new decoding buffer area, by the data pack buffer that receives to new decoding buffer area, turn back to step 3a1).

3b) packet decoding is carried out to encoded packet:

With reference to Fig. 4, being implemented as follows of this step:

3b1) receiving terminal first carries out decoding buffer memory to the encoded packets number of decoding end nonlinear correlation when reaching N after receiving packet, and this N number of packet is set to a decoded packet;

3b2) receiving terminal network code NC layer extracts the TCP head of packet in above-mentioned decoded packet, puts into buffer memory;

3b3) receiving terminal network code NC layer again will through step 3b2) after remaining data division change into a grouping Matrix C:

$C=\left[\begin{array}{cccccc}{\mathrm{\α}}_{11}& {\mathrm{\α}}_{12}& {\mathrm{\α}}_{13}& {\mathrm{\α}}_{14}& {\mathrm{\α}}_{15}& C_{d1}\\ {\mathrm{\α}}_{21}& {\mathrm{\α}}_{22}& {\mathrm{\α}}_{23}& {\mathrm{\α}}_{24}& {\mathrm{\α}}_{25}& C_{d2}\\ {\mathrm{\α}}_{31}& {\mathrm{\α}}_{32}& {\mathrm{\α}}_{33}& {\mathrm{\α}}_{34}& {\mathrm{\α}}_{35}& C_{d3}\\ {\mathrm{\α}}_{41}& {\mathrm{\α}}_{42}& {\mathrm{\α}}_{43}& {\mathrm{\α}}_{44}& {\mathrm{\α}}_{45}& C_{d4}\\ {\mathrm{\α}}_{51}& {\mathrm{\α}}_{52}& {\mathrm{\α}}_{53}& {\mathrm{\α}}_{54}& {\mathrm{\α}}_{55}& C_{d5}\end{array}\right]$

Applying Elementary Row Operations will be carried out to above-mentioned grouping Matrix C, obtain decoding matrix D:

Wherein, decoding matrix D rightmost one arranges the corresponding data bag obtained of decoding exactly, i.e. D ₁, D ₂, D ₃, D ₄, D ₅for the packet of gained of decoding;

D 3b4) will obtained ₁, D ₂, D ₃, D ₄, D ₅this column data bag successively with step 3b2) in transmission control protocol TCP head assemble, complete one group of decoding, and submit to transmission control protocol TCP layer, turn back to step 3b1), until all data complete decoding.

Effect of the present invention can be further illustrated by following emulation experiment:

1, experiment condition:

This experiment is based on NS3 instrument the Realization of Simulation, and emulate transmission control protocol TCP and the network throughput based on the transfer control method of random linear network encoding respectively, scene is single-hop networks scene and multihop network scene, and error rate scope is: 10 ^-6~ 10 ^-3, chain-circuit time delay is 10ms, and link capacity is 1Mbps.Network code packet size is N=5, and the finite field size of random linear network encoding is 2 ⁸, for the sake of simplicity, the jumping figure of multi-hop emulation is set to 3 jumpings.

2, experiment content

Experiment one: under single-hop networks scene, diplomatic copy invention and the throughput of transmission control protocol TCP and the relation of the error rate, result curve as shown in Figure 5.

Fig. 5 shows, the error rate is 10 ^-6~ 10 ^-4time in scope, transmission control protocol TCP performance sharply declines, and the present invention is not when 0 in the error rate, network throughput higher than transmission control protocol TCP throughput, and throughput to control Transmission Control Protocol with the speed ratio transmission that the error rate declines slow.

Experiment two: under multihop network scene, diplomatic copy invention and the throughput of transmission control protocol TCP and the relation of the error rate, result as shown in Figure 6.

Fig. 6 shows, transmission control protocol TCP and network throughput of the present invention all can decline along with the rising of the error rate, but under multi-hop scene, network throughput of the present invention when the error rate is higher far above the network throughput of transmission control protocol TCP, this affects less causing by RTT two-way time due to the present invention, and therefore the present invention is more suitable for the higher situation of the error rate in wide area network.

Claims (4)

1. based on a transfer control method for random linear network encoding, it is characterized in that, comprise the steps:

(1) between the transmission control protocol TCP layer and Internet protocol IP layer of transmitting terminal and receiving terminal, network code NC layer is added;

(2) the network code NC layer of transmitting terminal carries out grouping random linear network encoding to the packet of transmission control protocol TCP, and is sent to the Internet protocol IP layer of local terminal;

(3) the network code NC layer of receiving terminal receives encoded packet from the Internet protocol IP layer of local terminal, replys successively and packet decoding, and submit to transmission control protocol TCP layer to these packets.

2., as claimed in claim 1 based on the transfer control method of random linear network encoding, it is characterized in that the grouping random linear network encoding in described step (2) carries out as follows:

2a) packet of transmission control protocol TCP layer arrival network code NC layer is carried out buffer memory by transmitting terminal, and when the packet number of buffer area reaches N, then these N number of data are set to a grouping, N is the number of prespecified order;

2b) take out the original tcp data handbag head in above-mentioned grouping, carry out buffer memory;

2c) transmitting terminal produces coding core, and namely length is a random vector of N, each value stochastic generation in galois field in this random vector;

2d) under galois field, the n-th random number in this random vector is multiplied with the n-th packet in this above-mentioned grouping, and the results added that will obtain, n≤N;

2e) using core and the 2d of encoding) in the result of calculation that obtains repack as data, and add 2b successively) in the TCP head of institute's buffer memory.

3., as claimed in claim 1 based on the transfer control method of random linear network encoding, it is characterized in that the response in described step (3) is carried out as follows:

3a) receiving terminal is by the encoded packets that receives stored in decoding buffer area, and judges the decoding bag grouping whether this encoded packets belongs to current decode pointer and point to:

If newly arrived encoded packets belongs to the decoding bag grouping pointed by current decode pointer, then check whether the number of this block encoding bag is N, if N then decodes, and host-host protocol TCP layer is submitted in the grouping of successfully decoded, perform step 3b);

If newly arrived encoded packets does not belong to the decoding bag grouping pointed by current decode pointer, then perform step 3d);

Described decode pointer, refers to the integer pointing to the current encoded packets grouping not having to decode;

3b) decode pointer is pointed to the grouping of next decoding bag, and whether the number of packet is N in judging the grouping that decode pointer points to, if N then continues decode pointer to be pointed to the grouping of next decoding bag, until the decoding package pointed by it is not N, perform step 3c);

3c) receiving terminal sends to transmitting terminal and retransmits the information of encoded packets, wherein needs the number that retransmits for the number of packet in N deducts pointed by current decode pointer decoding package;

3d) open up new decoding buffer area, by the data pack buffer that receives to new decoding buffer area, return and perform step 3a).

4. as claimed in claim 1 based on the transfer control method of random linear network encoding, it is characterized in that, packet decoding in described step (3), carry out as follows:

3e) receiving terminal first carries out decoding buffer memory after receiving packet, when the encoded packets number to decoding end nonlinear correlation reaches N, this N number of packet is set to a decoded packet;

3f) receiving terminal network code NC layer extracts the transmission control protocol TCP head of packet in above-mentioned decoded packet, puts into buffer memory;

3g) receiving terminal network code NC layer again will through step 3f) after remaining data division change into a grouping Matrix C:

$C=\left[\begin{array}{cccccc}{\mathrm{\α}}_{11}& {\mathrm{\α}}_{12}& {\mathrm{\α}}_{13}& {\mathrm{\α}}_{14}& {\mathrm{\α}}_{15}& C_{d1}\\ {\mathrm{\α}}_{21}& {\mathrm{\α}}_{22}& {\mathrm{\α}}_{23}& {\mathrm{\α}}_{24}& {\mathrm{\α}}_{25}& C_{d2}\\ {\mathrm{\α}}_{31}& {\mathrm{\α}}_{32}& {\mathrm{\α}}_{33}& {\mathrm{\α}}_{34}& {\mathrm{\α}}_{35}& C_{d3}\\ {\mathrm{\α}}_{41}& {\mathrm{\α}}_{42}& {\mathrm{\α}}_{43}& {\mathrm{\α}}_{44}& {\mathrm{\α}}_{45}& C_{d4}\\ {\mathrm{\α}}_{51}& {\mathrm{\α}}_{52}& {\mathrm{\α}}_{53}& {\mathrm{\α}}_{54}& {\mathrm{\α}}_{55}& C_{d5}\end{array}\right]$

Applying Elementary Row Operations will be carried out to above-mentioned grouping Matrix C, obtain decoding matrix D:

Wherein, decoding matrix D rightmost one arranges the corresponding data bag obtained of decoding exactly, and namely D1, D2, D3, D4, D5 are the packet of decoding gained;

3h) by this column data bag of D1, D2, D3, D4, D5 of obtaining successively with step 3f) in transmission control protocol TCP head assemble, complete one group of decoding.