A Study On The Performance Of Full Duplex Relay Systems

A promising technology for next generation wireless networks is relaying,which can provide significantly improved throughput and coverage.Nevertheless,most existing works on relaying only focus on the half-duplex mode(i.e.,half-duplex relaying(HDR))due to its implementation simplicity.This leads to an inherent spectral efficiency loss as the orthogonal channel use is required for relay transmissions.With recent advances in self-interference cancellation technologies,researches have shown the feasibility of full-duplex wireless,which allows radios to receive and transmit on the same frequency band simultaneously.Indeed,full-duplex relaying(FDR)has received a lot of attentions from both academia and industry to further improve the performance of next-generation wireless networks.How to analyze and measure the theoretical performance limits of FDR systems is a fundamental problem.Based on the basic three-node relay model,the outage performance of an amplify-and-forward(AF)FDR protocol is studied.We provide a new closed-form expression for the outage probability that captures the joint effect of residual self-interference(RSI)and a direct link.In addition,when the processing delay of the relay is larger than 1,which is often the case in practice,the proposed closed-form outage performance expression still applies.Finally,all the theoretical results are validated through numerical simulations.Conventionally,relays are used to enhance the coverage and improve the signal-to-noise ratio(SNR).However,introducing relays can also aid interference management and improve the degrees of freedom(DoF)of the system.Interference neutralization(IN)is a novel interference management technique found from relay-assisted interference networks.In this thesis,we study the feasibility of IN for a two-user interference channel(IC)with a multi-input-multi-output(MIMO)instantaneous FDR.Assuming linear transceivers with an amplify-and-forward(AF)relay,we first present the necessary condition for generalized IN.Then,we derive the necessary and sufficient conditions for coordinated IN and pure IN.The derived sufficient conditions give rise to the minimum relay antenna configuration to support interference-free transmission.Our proof throws lights on how to use the relay resources to neutralize the interference efficiently.