Direction of arrival estimation of coherent wideband LFM signals in multipath environment

A novel direction of arrival (DOA) estimation method is proposed for coherent wideband linear frequency modulated (LFM) signals in multipath environment. In this method, the wideband LFM signals are first transformed into fractional Fourier (FRF) domain to construct the array model, in which time-variant steering vector is changed into time-invariant one and wideband LFM signals are converted to narrowband stationary ones. Afterwards, the coherent wideband LFM signals are resolved separately by performing a Toeplitz decorrelation scheme on the covariance matrix. Then, the DOAs of coherent wideband LFM signals are estimated by the signal parameters via rotation invariance technique (ESPRIT). The proposed method can resolve more coherent wideband LFM signals without reducing the array aperture, and can obtain more accurate DOA estimation at low SNR with a low computation complexity. Simulation results demonstrate the effectiveness and efficiency of the proposed method.