DOA Estimation for Distributed Sources With the Mixture of Circular and Noncircular Signals: A Rank-Reducing Method

With the development of urbanization, more communication applications emerge in dense urban areas. Local scattering caused by buildings and vehicles in cities poses challenges to the signal parameter estimation. Also, the evolution of modulation techniques leads to the fact that different types of signals could propagate to the sensors array simultaneously, leading to a high computational load. Therefore, in this article, we propose a low-complexity direction-of-arrival (DOA) estimation algorithm for the coherently distributed (CD) sources under the coexistence of circular and noncircular (NC) signals. The rank-reducing theory is adopted to decouple the interested DOA from other nuisance parameters. Theoretical analysis and numerical simulation results are provided to illustrate the superiority of our algorithm. A remarkable decrease in complexity is observed with slight degradation of direction-finding accuracy. It is also proved that the proposed algorithm is not restricted by the types of the angular distribution.