Research On Relay Selection Scheme For Full-Duplex Cooperative Communication Systems

The unprecedented growth in wireless devices and mobile data traffic has motivated the research and development of next generation wireless networks with higher data rate,spectrum efficiency,and energy efficiency.As a promising technology which can not only effectively utilize various network resources,extend the coverage,but also improve the efficiency of the spectrum,full-duplex(FD)cooperative communication technology has become a hot research topic.With the FD mode,the relay node will receive the self-interference with the same frequency at the same time and the destination node will receive the direct-link signal as well.Considering both the residual self-interference(RSI)and the direct-link signal,this paper proposes an optimal relay selection(ORS)strategy for the FD cooperative networks with different relaying protocols,where two cases are considered according to whether the diversity combining technique is adopted or not.Then,the system performances are analyzed and verified by simulations.The main contributions are as follows:For the FD relaying systems without diversity combining technique,this paper first investigates the ORS schemes based on maximizing the instantaneous capacity by taking the RSI and the direct-link interference into consideration.Then we analyze the outage probability of proposed schemes for FD relaying cooperative networks under DF and AF protocols and derive the closed-forms expression of outage probabilities.Simulation results are shown to validate the analytical results and demonstrate the significant performance gain of the proposed schemes compared with the conventional schemes which neglect the direct-link interference.Then,the results show that the FD ORS schemes considering the direct link indeed improve the system performance even if the direct link exists as an un-selectable link.For the FD relaying systems with combining method,we first investigate the ORS scheme based on maximizing the instantaneous capacity by taking the RSI and the desired direct-link signal into consideration for FD DF cooperative networks.Then,we analyze the outage probability of the proposed scheme and derive the closed-form expression.Simulation results are shown to validate the analytical results and demonstrate the significant performance gain of the proposed scheme compared with the conventionalscheme especially in the middle signal-noise-ratio(SNR)range.As for the FD AF cooperative networks,it is found that the selection result of ORS scheme based on maximizing the instantaneous capacity is the same as that of the conventional scheme.What's more,for small RSI,the system performance of the ORS scheme with DF protocol is superior to that of the scheme with AF protocol and the larger loop interference makes the result reversed.