Research On Transmission Scheme Of Co-time Co-frequency Full Duplex Relay Based On SC-FDE

As a research hotspot,the FDR(full duplex relay)technology has aroused more and more attention in recent years.The FDR system can transmit and receive data in the same time and same frequency band,theoretically doubling the spectral efficiency compared with the traditional half duplex communication.In addition,it has the advantages of expanding the cell's coverage area and improving the QoS(Quality of Service),so it would be a promising key technology of the coming 5th generation communication system.Its application is helpful to solve the problem of data traffic rapidly soaring in the today society.SI(Self interference)is the core component of limiting the performance of FDR system in the relay node.As the SI cannot be completely cancelled by the present technogy,the residual part repeatedly reruns in the loop,degrading the system's SINR(Signal to Interference plus Noise Ratio).The FDR system with AF(amplify-and-forward)protocol can automatically control the gain by optimizing the amplification factor,so as to achieve the goal of reducing the power of transmision signal and improving the quality of the end to end link.The traditional schemes of gain control usually consider the received signal from the source node to be useful,and the feedback signal from the loop interference channel is considered to be interference,thus losing the power of the signal.Based on the traditional schemes of gain control,we propose a new scheme of FDR equivalent channel.It regards the first several sub-cycles signal as multipath signal in the relay loop and acquires the realization of the reduced ISI(inter symbol interference),obtaining better BER performance of the FDR system depending on the fact that CP(cyclic prefix)of SC-FDE overcomes the multipath fading.The main contents of this paper are listed as follows:(1)We briefly introduce the structure of SC-FDE system and prove that CP can effectively combat the multipath fading based on matrix theory.(2)We study the principle of the FDR system and investigate two classical schemes of gain control:maximum power scheme and Wichman scheme.Deduction of the optimal amplify factor,maximum SINR(Signal to Interference plus Noise Ratio)and the corresponding outage probability of these two schemes is also fulfilled.The difference of the two schemes is depicted in simulation results.(3)We propose a novel scheme of full duplex relay equivalence channel based on the Wichman scheme.The principle of the scheme that operates and gets down the system's ISI in the equivalent channel is presented.We derive analytical expression of the optimal amplify factor and SINR.Simulation results confirm the validity of our scheme.Besides,we focus on the effect of relay and destination nodes' noise,the SI level and the modulation mode on the BER of FDR system based on that.Simulation results suggest that the scheme indeed outperform the optimal gain control one in the BER performance.