Research On Performance Analysis Of Backscatter-based Cooperative NOMA Communication Systems

With the high-speed development of Io T,the surge of wireless devices causes the scarcity of spectrum resources to wireless communication systems.Ambient backscatter communication(Am BC)and non-orthogonal multiple access(NOMA)are important technologies to improving the spectrum efficiency of Io T,and the combination of Am BC and NOMA can alleviate the shortage of spectrum resources.At the same time,in real communication scenarios,transceiver architectures are bound to suffer from radio-frequency front-end related impairments,among which in-phase/quadrature-phase imbalance(IQI)constitutes a major impairment in transceivers.Therefore,it is important to study the performance of backscatter-based cooperative NONA systems under IQI.In addition,the passive nature of backscatter communication makes it challenging to guarantee its security of backscatter.Therefore,there is an urgent need to investigate the physical layer security(PLS)performance of the backscatterbased cooperative NOMA communication systems.For the considered backscatter-based cooperative NOMA(BC-NOMA)system with the RF front-end suffered from IQI,the exact expressions for the outage probability,the average rate,and the asymptotic expressions for the outage probability at high signal-to-noise ratio(SNR)are derived.Furthermore,the performance of the proposed BC-NOMA scheme is compared to that of the non-cooperative NOMA(NC-NOMA)scheme.Monte Carlo simulation verifies the accuracy of the theoretical analysis.Simulation results show that IQI will cause that the system has not only the excessive outage probability but also the loss of average rate.In addition,it will be shown that the BC-NOMA system outperforms the NC-NOMA system.For the considered backscatter-based cooperative NOMA(BC-NOMA)system,where the eavesdropper is assumed to have the same decoding capability as legitimate users,the exact expression of the secrecy outage probability(SOP)and its asymptotic expression under high SNR are derived.Monte Carlo simulation verifies the accuracy of the theoretical analysis.For the considered BC-NOMA system,simulation results show that: i)As the transmit power of base station increases,the SOP of the legitimate users decreases;ii)As the power allocation factor of the near user increases,the SOP of the near user decreases and the SOP of the far user increases;iii)As the target secrecy rate increases,the SOP of the legitimate users increases.