Multitarget AOA Estimation Using Wideband LFMCW Signal and Two Receiver Antennas

Abstract

Linear frequency modulated continuous wave (LFMCW) signals have been widely used in target detection and localization, thanks to their good detection sensitivity and high range resolution. However, estimation of the angle of arrival (AOA) of the LFMCW signal reflected from each target in a multitarget environment is still quite limited at present. In this paper, we propose a novel AOA estimation framework in which one transmitter antenna and two receiver antennas are employed to transmit a wideband LFMCW signal and receive the signals reflected from different targets, respectively. The signals received at two receiver antennas are processed in three steps. First, each of them is demodulated by mixing with the transmitted signal to transform the wideband nonstationary signal into superposition of a series of single-tone signals. Second, signals received at each receiver antenna from different targets are separated using bandpass filtering. Third, the corresponding AOA of each target is estimated using the phase difference between two receiver antennas. Different from the traditional subspace-based methods, the number of targets is not limited by the number of receiver antennas. The theoretical analysis and simulation results show that the proposed algorithm can achieve accurate AOA estimation for multiple targets even at a low signal to noise ratio.