Spatial smoothing for arrays with arbitrary geometry

The spatial smoothing (SS) technique has been proved to be effective in decorrelating coherent signals thus making MUSIC algorithm operative in a coherent interference environment. However, such scheme can only be applied to uniformly spaced linear arrays which are known to be very sensitive to the directions of arrivals (DOAs) and can be used to estimate azimuth angles only. To significantly improve the robustness of DOA estimation, to estimate both azimuth and elevation angles, we developed techniques for applying SS on arrays with arbitrary geometry. We also study the cause of ambiguities in a multiple signal environment and find the necessary and sufficient conditions of an ambiguity free three-sensor array manifold. We evaluated the forward/backward spatial smoothing on a nonlinear array with central symmetry and found that this technique outperform regular SS in terms of improved efficiency and estimation resolution. Finally, we expand the application of our technique to ESPRIT. All the predicted results are verified by simulations