Research On Relay Selection For In-band Full Duplex Communication Networks

In-band full duplex communication is one of the core technologies of next generation communication,which have important applications in current 5G and even future 6G communication.Different from the conventional half duplex communication mode,full duplex mode can transmit and receive signals in the same frequency band simultaneously,which also enables full-duplex communication to provide higher spectral efficiency.However,for the full duplex terminal,the transmitted signal will coupled to the received signal,resulting in loop interference between the transmitted and received links.The loop interference damages system performance seriously.The integration of antenna isolation,radio frequency cancellation and digital cancellation can effectively reduce the influence of loop interference and increase the practicability of full-duplex communication.This paper focuses on the problem of relay selection in the full duplex wireless communication system.Different relay selection strategies make decisions based on different channel state information.In this paper,outage probability is taken as an evaluation index to analyze the system performance provided by different relay selection strategies.Firstly,we take Rayleigh fading channel as the channel model,and studies the outage performance for different relay selection strategies without channel estimation error and quantization error.Based on the expression of channel capacity and the statistical distribution of various channel parameters,analytic solution expressions of outage probability for different relay selection schemes are obtained.In addition,two power allocation algorithms are also provided,and the optimal power allocation factors are obtained,respectively.Secondly,we investigate the influence of quantization error caused by low resolution analog-to-digital converter and estimate error.By modeling the two errors,we further obtain the analytic solution expressions of outage probability for different relay selection schemes with them.Finally,we extend the communication scenario to vehicle-to-vehicle communication networks.The vehicle-to-vehicle communication is one of the ideal scenarios for full duplex communication which can largely meet the requirements of loop interference cancellation technologies.The application of full duplex communication in vehicle-to-vehicle communication can significantly improve the reliability and timeliness of vehicle-to-vehicle networks.Different from common communication scenarios,in the vehicular networks,scatters are around both transmit and receive antennas.All of these antennas are usually in high-speed motion.Therefore,vehicular networks may suffer severer channel fading than conventional communication networks.We analyze two channel models which are suitable for vehicle-to-vehicle communication.The new channel models are n-Rayleigh fading and Nakagami fading.The approximate expressions of outage probability for different relay selection strategies based on above two channel fading models are also derived,respectively.Based on the expressions,influence of different channel fading models on system outage performance is analyzed.In conclusion,this paper systematically investigates the full-duplex multi-relay system,which is helpful to improve the research depth of full-duplex relay and provide effective support for its practical application.