DOA estimation under the coexistence of nonuniform noise and mutual coupling

This paper investigates the problem of direction-of-arrival (DOA) estimation under the coexistence of nonuniform noise and mutual coupling. Though either the issue of nonuniform noise or mutual coupling has been widely discussed in the literature, the problem of DOA estimation in the specific scenario where these two issues coexist still remain open. As far as we know, the existing algorithms for mutual coupling calibration require a uniform white noise environment in general, and on the other hand, the techniques for nonuniform noise environments are proposed for well-calibrated arrays (i.e., without unknown mutual coupling and other errors). In this work, we attempt to estimate the DOAs in the coexistence case. Towards this end, a two-stage least squares (LS)-based approach is developed. In particular, the signal and noise subspaces are estimated by solving an LS minimization problem in the first stage. Next, the DOAs are estimated through a subspace-based approach taking into account the special structure of the mutual coupling matrix (MCM). Numerical examples are provided to illustrate the performance of the proposed method.