Interference Mitigation Method And Performance Research Based On Nonlinear OFDM Receiver

Orthogonal Frequency Division Multiplexing(OFDM)is a multicarrier modulation technology,which has extensive applications in wireless communication systems.However,in practical applications,OFDM receivers are often exposed to impulsive noise.As the statistical property of impulsive noise is quite different from that of additive white Gaussian noise(AWGN),the error rate of OFDM system over impulse noise channel degrades drastically.Therefore,it is of great significance to conduct research on impulse interference mitigation for OFDM system.To improve the performance of OFDM system,the interference mitigation methods and performance analysis are investigated.The main contributions are summarized as follows:Firstly,to quantitatively analyze the reliability performance of nonlinear OFDM receiver with interference mitigation methods,the analytical signal to noise rate(SNR)expressions of OFDM receiver with peak value blanking and peak value clipping in frequency selective fading channel based on Bernoulli-Gaussian impulsive noise model are derived.Furthermore,symbol error rate(SER)performance of nonlinear OFDM receiver over frequency selective Rayleigh and Ricean fading channels with multiple phase shift keying(M-PSK)modulation and multiple quadrature amplitude modulation(M-QAM)modulation is presented based on the expressions.Finally,simulation results are provided to show good agreement with theoretical results.Following conclusions can be obtained: 1)each subchannel of the nonlinear OFDM receiver has the same SER performance.2)Comparing to the regular and peak value clipping method,the peak value blanking method has the best SER performance.Secondly,to solve the problem of the blanking threshold optimum setting in nonlinear OFDM receiver,a method based on maximizing signal-to-interference and noise ratio(SINR)criterion is presented in this paper.The closed-form expression of average output SINR over Rayleigh fading channel is derived.Then,the optimum blanking threshold is further given based on the maximizing SINR criterion.Finally,the symbol error performance of nonlinear OFDM receiver over Rayleigh fading channel based on the optimum blanking threshold is given,the simulation results demonstrate that the theorical result of optimal blanking threshold agrees with computer simulation.