Full Duplex Relay Transmission Based On OFDM

In recent years,communication technology developed rapidly,technologies like 4G has been widely commercialized,and meanwhile,5G is constantly advancing.Society has pay more and more attention on new technologies such as Self-driving technology,Internet of things.Higher reliable,lower transmission delay,wider bandwidth as well as wider coverage area are required when they are applied in the future.One of the potential technologies(applications)of 5G is in the scheme of Full-duplex relay transmission,the node will transmit and receive at the same time and the same frequency band,and compare with the half duplex relay transmission scheme,it double the spectrum efficiency theoretically,which will solve the problem that currently,the lack of spectrum.One of the main drawback on development of the full-duplex relay transmission technology is the existence of the loop self-interference signal.Many related research groups have made contribution in the aspect of the interference elimination,but the current technology is limited.There will be residual loop self-interference signals still.The residual loop selfinterference signals in full-duplex relay node will be iteratively iterated,which will affect the transmission performance of the system.In this situation,I studied and analyzed the transmission system of unidirectional and bidirectional full-duplex relay from both theory and practice in this paper.First,based on unidirectional full duplex relay transmission model and mathematically analyzing of fullduplex relay signals iterative expressions,the relay equivalent channel model was established.Then in order to reduce the impact of residual loop self-interference signals on the system the cyclic prefix of OFDM was applied.At the same time,with the help of maximize the SINR in receiving node,the method of solving the best amplification factor of relay was obtained.In addition,the transmission performance of the optimal amplification factor and equivalent multipath scheme were analyzed by simulation.Besides,the two new scheme in the bidirectional full-duplex relay transmission model was proved.After all,analyzed the transmission performance by simulation for bidirectional full-duplex relay transmission and compared with unidirectional case.The above schemes are all based on the ideal channel estimation.The performance of full-duplex relay transmission in practical applications are studied in the following context.A full-duplex relay transmission scheme which can be applied to the real actual channel scene is proposed by adding channel pre-estimation,channel monitoring and correction plan,.The error rate performance of actual channel estimation and ideal channel estimation are compared and analyzed.The scheme mentioned in this paper has a better performance at the high SINR or low self-interference suppression level.Finally,realized the full-duplex relay transmission based on OFDM at the USRP and MATLAB platform;proved and analyzed the feasibility of full duplex relay transmission and the actual error rate performance of full-duplex transmission.