Two-Way Full Duplex Cooperative Space-time Coding Based On Self-Coded Loop Interference

In recent years,the trend of wireless communication shows that wireless communication tends to have higher transmission speed,wider range of transmission,more efficient spectrum utilization,so cooperative relay and full-duplex(FD)which have the above advantages will become the key technology of future wireless communication.Compared with the half duplex(HD)relay,the FD relay can achieve twice spectral efficiency as the HD relay,and greatly improves the system capacity.The traditional HD relay can obtain the cooperative diversity gain with distributed space-time coding(DSTC),however the inherent self-interference problem harms the system performance when applying the DSTC directly to the FD relay.In order to solve the self-interference of the FD relay,the space-time coding based on self-interference is studied in this paper.Furthermore,power allocation algorithm is investigated in order to improve the system performance.The main work of this paper is listed as follows:Distributed space-time coding scheme based on self-interference is studied.Firstly,the self-interference signal model of the two-way FD relay is analyzed,and the self-convolution character of the residual self-interference of the FD relay is obtained.Secondly,based on the study of the distributed linear convolution space-time coding(DLC-STC)in the cooperative relay system,we design the full-duplex space-time coding scheme using the self-convolution characteristics of the self-interference combined with the direct link.At last,in order to optimize the performance of two-way full-duplex space-time coding scheme,the signal-to-interference ratio(SINR)of the terminal node is derived,and the optimal relay amplification factor is obtained based on maximizing the smaller SINR of T1 and T2.The simulation results show that the proposed scheme has good robustness to the residual self-interference of the relay and can obtain full diversity gain.The power allocation algorithm of the distributed space-time coding scheme based on self-interference is proposed.Based on the analysis of the channel capacity of the HD and FD relay,the system performance of the HD and FD with different degrees of self-interference is improved with power allocation,which is also proved by simulation.The amplification factor and the power allocation of the distributed space-time coding scheme based on self-interference are jointly optimized by maximizing the smaller SINR and the channel capacity.The simulation results show that the power allocation algorithm improves the performance of the distributed space-time coding scheme based on self-interference.