Multipath direction finding in both multiplicative noise and additive noise environments via exploitation of cyclostationarity

This work examines the direction estimation problem in the presence of multipath propagation and when the received signal is corrupted by both multiplicative noise and additive noise, which is often encountered in actual wireless communication systems. By exploiting cyclostationarity of the signals, a multipath direction finding algorithm using third-order cyclic moment is proposed to detect multiple nonGaussian cyclostationary coherent sources in the complicated noise environments. The forward-backward spatial smoothing method is developed in cyclic covariance matrix to resolve the directions of multiple coherent signals of interest (SOIs). The simulation results indicate that the proposed method can effectively resolve directions of multiple coherent SOIs even if the total number of impinging signals is no less than the number of sensors. The stationary additive and nonzero-mean multiplicative noises with any distribution can be suppressed no matter the noises are Gaussian and nonGaussian, white or colored. Also, the cyclostationary interference with different cyclic frequency from the SOIs can be effectively removed.