Research On Full Duplex Bidirectional Relay Method Robust To Residual Loop Interference

With the portable and popularization of mobile terminals,there is a growing demand for high-speed data services such as online payment,video communication,office,and games.Thus,the wireless communication systems must be able to achieve high-speed multimedia services and data services in the future.The full duplex(FD)relay technique,which allows the relay to transmit and receive signals over the same frequency band at the same time slot,has the potential to double the spectral efficiency in comparison with the traditional half duplex(HD)relay technique.The full duplex relay technology helps solve the problem of dramatic increase in mobile Internet traffic.However,full-duplex relay nodes have serious loop interference,which is leaking from the FD node's transmission to its own reception.Several techniques of suppressing the loop interference have been proposed,but the loop interference cannot be removed totally.The residual loop interference(RLI)still limits the performance.Therefore,we propose an two-way FD relaying scheme,which is robust to the residual loop interference.In this thesis,we first briefly introduce the status and basic principles of full-duplex relay technology and SC-FDE technology.Then we compare the two-way half duplex relay system and two-way full duplex relay system transmission scheme,and the relay equivalent channel model is established according to the transmission process of the residual loop interference signal in the relay node.That is the remaining loop interference is equivalent to multipath signals within several cycles between relay transmit and receive antennas.So that we can use SC-FDE to combat the stronger residual loop interference formed by multipath effects.At the same time,we obtain the optimal amplification factor of the relay node by maximizing the signal-to-noise ratio to eliminate the symbol trailing formed by the residual loop interference.Furthermore,for multi-relay scenarios,we propose a multi-relay transmission scheme combining relay selection technology with relay-equivalent channel transmission scheme.It can be proved by simulation that the relay equivalent channel transmission scheme can effectively reduce the influence of the residual loop interference,improve the system reliability and simplify the processing of the residual loop interference of the relay node.More importantly,it can be combined with relay selection technology,applied to multi-relay scenarios.Simulation results are presented to evaluate the performance of the proposed scheme and verify the theoretical analysis.