Performance Analysis Of Network-assisted Full Duplexing System Based On Stochastic Geometry

With the continuous popularization of new generation mobile devices such as smart phones and tablet computers,mobile data services have shown explosive growth.Diversified and personalized mobile communication services,such as high-speed uplink and downlink mobile data services and delay sensitive services,result in higher requirements for duplex techniques in next generation mobile communication system.Recently,a novel full-duplex method named as network assisted-full duplexing(NAFD)has been proposed.NAFD can be regarded as a unified duplex technology,flexible duplex,hybrid duplex,full duplex and other duplex methods are all its special forms.For NAFD technology,all remote radio heads(RRHs)are connected to the baseband unit through high-speed optical cables,so the downlink-to-uplink interference can be eliminated in the digital domain.In addition,stochastic geometry is a powerful mathematical tool for modeling,analyzing and designing wireless networks.The signal to interference plus noise ratio(SINR)and spectral efficiency performance of two kinds of NAFD systems using stochastic geometry are analyzed in this paper.Firstly,the application of stochastic geometry theory in modeling and analyzing downlink cellular network and uplink cellular network is introduced,which provides a theoretical basis for the subsequent stochastic geometry based performance analysis of the NAFD system.Then,the SINR coverage probability and spectral efficiency of the flexible duplex system with directional antennas are studied by using stochastic geometry theory.Based on this model,the theoretical expressions of the downlink and uplink SINR coverage probability,the instantaneous achievable rate coverage probability and the average achievable rate are derived respectively.The theoretical expressions of SINR coverage probability is verified by Monte Carlo simulations.In addition,the numerical results show that the NAFD flexible duplex system outperforms both the traditional flexible duplex system and the time division duplex system in spectral efficiency.Finally,the SINR coverage probability and spectral efficiency of the hybrid duplex system are studied by using stochastic geometry theory.Based on this model,the theoretical expressions of SINR coverage probability and average achievable rate are derived.The theoretical expressions of SINR coverage probability is verified by Monte Carlo simulations and the spectral efficiency of the hybrid duplex system is analyzed.For SINR coverage probability,numerical results show that when the hybrid duplex system has perfect self interference cancellation,the change of RRH density has little effect on SINR performance;When the self interference cancellation capability of hybrid duplex system is poor,the greater the density of RRH,the better the SINR performance of the system.For spectral efficiency,numerical results show that in order to maximize the spectral efficiency of the hybrid duplex system with perfect self interference cancellation,all RRHs should be operated in FD mode.