Sequential DOA estimation method for multi-group coherent signals

In order to cope with multi-group coherent signals induced by multipath propagation, this paper presents a novel approach to estimate the direction of arrivals (DOAs) of each group sequentially. For each time, we just estimate the DOAs of one group which has the minimum coherent signals based on forward spatial smoothing (FSS), and the information of this group is eliminated from the array covariance matrix with oblique projection technique. Then we estimate the next group similarly until all groups are estimated. Afterwards, we use the forward/backward spatial smoothing (FBSS) to further improve the estimation accuracy of the DOAs in each group separately. The new method not only utilizes less array sensors to resolve multi-group coherent signals, but also estimates the same DOAs from different groups. Simulation results are presented to demonstrate the effectiveness of the proposed method especially in low signal-to-noise ratio (SNR) and small number of snapshots.