Research On Network Transmission Scheme Based On Circular-Shift Linear Network Coding

With the development of mobile communication,wireless multi-hop network plays an increasingly important role in production and daily life.Traditional routing schemes can not meet the requirements of large capacity,high reliability and low latency for wireless multihop networks due to uneliminated multi-hop error accumulation.Network coding becomes one of the solutions of future wireless communication because of its reachable capacity and other advantages.However,in the current network coding schemes,high computational complexity caused by large finite field and the high packet delay caused by block transmission restrict its practical application.To solve these two problems,this paper proposes a multi-hop endurance transmission scheme based on circular-shift linear network coding,and extends it to multipath multi-hop wireless networks,providing some new perspectives for future wireless communication.The main work of this paper is as follows:(1)A multi-hop network endurance transmission scheme based on circular-shift linear network coding is proposed.In this scheme,the source node precodes a group according to the network capacity in order to improve the success rate of the group in the first transmission.The intermediate node uses a special upper triangular block matrix to recode the received packets: in the recoding matrix,the corresponding columns of the correctly received packets are zero matrix except the diagonal position of the unit matrix.In the corresponding columns of the lost packets,only the rows corresponding to the correctly received packets of the same group have non-zero coefficient matrix,and the other positions are zero matrix.This upper triangular block matrix can be used to recode the packets so that the correctly received packets do not stay in the intermediate node and are directly forwarded down,which greatly reduces the transmission delay of these packets.It is proved that the recoding matrix can satisfy the maximum distance separability and improve the decoding probability of the receiver.The feedback mechanism is introduced at the receiver to further improve the transmission reliability,and the feedback times are limited to ensure that the maximum packet delay will not exceed.The theoretical analysis of the scheme proves its capacity reactibility,gives the average delay of the scheme,and compares its computational complexity with scalar code.Simulation results show that when the packet loss rate is low,this transmission scheme can achieve throughput close to capacity and keep low delay and success rate above 99.7%.(2)Soft handoff scenario in mobile communication can be modeled as a multipath multihop network.Aiming at the problem of low transmission efficiency of soft handoff,three network coding schemes,i.e.,proportional allocation before coding,coding before average allocation and coding before proportional allocation,are proposed on the basis of circularshift linear network coding endurance scheme.First,the coding efficiency of traditional soft handoff and three network coding schemes is compared.The results show that the three network coding schemes can achieve higher coding efficiency and higher success rate.The coding before average allocation scheme performed best,achieving a success rate of more than 99.99% when the number of packets sent reached a low value.Then three network coding schemes are described in detail,and the packet delay and throughput expressions of each scheme are given.It is particularly innovative to add the point-to-point feedback on the path with poor channel condition to the coding before proportional allocation scheme,which is independent of the end-to-end feedback.A separate maximum retransmission times is introduced,which can make more efficient use of the network in the case of different path capacity disparity.Finally,the simulation results show that the performance of the proposed three network coding schemes is the best,which can approach the network capacity when the group is large,and keep the lowest delay and the success rate of more than 99.3 %.The performance of coding before average allocation,and then proportional allocation before coding decreases successively.But on the whole,the three transmission schemes proposed in this paper can achieve high throughput,low delay and success rate of more than 99%.