Two-way Serial Multi-relay Transmission Performance Based On Network Coding

Due to the limitation of physical communication distance and the impact of wireless channel fading,it is necessary to forward their data packets sequentially through multiple relays to complete wireless communication between two end users.This combination of two end users and multiple relay nodes forms a two-way wireless relay network.Existing literature has proven that if each node in the network adopts an appropriate network coding mechanism,a two-way serial relay network can obtain transmission performance superior to traditional store-and-forward technology.For example,for a single-relay bidirectional relay network,the analog network coding technology based on the amplyand-forward method and the digital network coding technology based on the decode-andforward method can obtain 100% and 33.33% higher theoretical transmission throughput than the store-and-forward technology,respectively.However,because analog network coding faces technical difficulties such as clock synchronization,self-information elimination,and channel state information estimation,this paper focuses on the design of a more practical two-way serial relay transmission mechanism based on digital network coding.In this respect,this paper first proposes a new two-way serial relay transmission mechanism based on decode-and-forward and digital network coding technologies.Its main advantage is that it supports a two-way serial relay network with any number of relay nodes to exchange two data packets in every three consecutive timeslots,so that it can obtain a superior transmission and spectral efficiency to the existing two-way serial relay transmission mechanism of the same type.Secondly,in order to solve the transmission error diffusion problem faced by the two-way serial relay network,we have designed an error control mechanism,This mechanism retransmits erroneous data packets in an appropriate manner by each network node,which can effectively correct transmission errors that may occur in the network without affecting the operation of the proposed two-way serial relay transmission mechanism.Numerical simulation results and analysis show that compared with the efficient store-and-forwaed scheme and two existing two-way serial relay transmission mechanisms based on digital network coding(ie,M-DF-NC and SNC-DM),the two-way serial relay transmission mechanism proposed in this paper under ideal channel conditions without transmission errors,the throughput increment of the relay transmission scheme in this paper can reach 66.67%?66.67% and 33.33% in the ideal condition,respectively.On the other hand,by combining with the error control mechanism proposed in this paper,this transmission mechanism can also obtain an effective transmission throughput over Rayleigh fading channels that is superior to MDF-NC and SNC-DM.