Research On Novel Transmission Technology In Two-way Relay Communication System

As one of the key enhancement technologies of wireless communication system,relay communication technology is an effective means to expand the coverage of wireless service,improve the communication quality of marginal users and promote the load balancing of communication network.Among them,two-way relay technology has attracted much attention because of its advantages,such as high spectral efficiency and low relay delay.In addition,in order to avoid the strong interference caused by the transmitted signal to the received signal,the nodes of two-way relay system mostly work in half-duplex mode,which will bring some resource loss to the wireless relay system.Therefore,it is of great theoretical value and practical significance to design an effective scheme to optimize the performance of the existing relay system by combining with the new technology.In order to improve the transmission reliability and capacity of the existing wireless two-way relay system,this paper combines two-way relay technology with the new diversity technology: space-time line code(STLC),and unmanned aerial vehicle(UAV)communication technology.Firstly,the performance of STLC-based multiple-input multiple-output(MIMO)two-way relay system is analyzed theoretically.Then,the joint optimization of relay trajectory and power allocation is carried out to improve the throughput of UAV assisted mobile two-way relay system.The main work of this paper are as follows:First of all,the theoretical performance of STLC-based MIMO two-way relay system is analyzed.The system model is firstly introduced carefully,and then the theoretical results of outage probability(OP)and average bit error rate(BER)of system under Rayleigh fading channel are uniquely provided,which have important guiding significance to the system design and performance optimization.Secondly,the research on performance enhancement of UAV-assisted mobile two-way relay system is presented.Based on the high mobility of UAVs,a model of UAV-assisted mobile bidirectional relay system is established,in which a UAV is deployed as relay to help exchange information between nodes on both ends of non-direct communication link.Under some constraints,such as: UAV's mobility,the limitation of relay's average power and peak power,and information causal constraints,the motion trajectory and power allocation of UAV are jointly optimized to maximize the system end-to-end throughput and the minimum average rate of between users.Lagrange dual method,successive convex approximation(SCA)and other mathematical methods are used to obtain the optimal resource allocation scheme.Simulation results demonstrate that the proposed joint optimization strategy perform better than the traditional benchmark.