Research On Relay-Assisted Wireless Networks Transmission With Network Coding

Network coding is an information fusion technology that allows to encode the information received linearly or nonlinearly at the intermediate node.Using network coding can make the transmission capacity approach to the theoretical maximum value.In the wireless network the relay coordination transmission based on network coding combines the advantage of network coding and the characteristics of the relay coordination transmission technology,which can effectively improve network throughput,reduce the power transmission consumption,and enhance network fault tolerance etc.This thesis focuses on the specific network scenario,researches on the network coding application in wireless relay cooperative communication.First,single relay cooperative broadcast and multicast transmission based on network coding are studied.In current relay coordination transmission the effect of relay coordination is not obvious,and the performance of package selection strategy is poor.A classified network coding retransmission approach based on the minimum set cover is proposed.In this scheme,to make full use of the advantage of relay-assisted transmission,lost packets of receivers are classified into two categories according to the packet reception status of relay node after the initial transmission,and then encoded for retransmission.For each classification,according to the corresponding status feed matrix search for encoding opportunities and generate encoding packets,and apply set cover problem to simulate the coded packets selecting procedure to minimize the number of retransmissions and improve retransmission efficiency.The analysis and simulation results show the effectiveness of the scheme proposed.Second,further focus on the application of network coding in the multiple source multiple relay wireless transmission.Current scheduling schemes in multi-relay wireless network mainly focus on single source wireless network with the same link status.Furthermore,the sequential-forward scheduling scheme is used usually,and the transmission efficiency is comparatively low.To solve this problem,a priority scheduling scheme based on random linear network coding is proposed.In different transmission stages,the feedback information is generated according to the packets accepting state or the linear relation among the encoding vectors.The number of the effective packets of the corresponding relay node is calculated.In the condition of different link status,the effective information of each relay node and the link transmission reliability is taken into consideration comprehensively to generate the priority index and complete scheduling.According to the simulation results,this scheme can effectively improve network throughput and reduce the number of retransmission compared with the traditional scheduling schemes for single source wireless network.