Combined beamspace and element space technique for partial adaptive concentric ring array

Partial adaptive concentric ring arrays (CRA) are very attractive for beamforming in 3-D, because they substantially reduce the computation time and improve tracking ability with respect to a fully adaptive CRA. In some practical situations the impinging signal contains some interferences whose characteristics such as directions of arrival (DOAs) could be estimated a priori. Previous partial adaptive CRA methods that utilize prior knowledge were not able to always maintain a low residual interference and noise level in the beam-former output. Even when they could, the performance degrades quickly if the estimated characteristics of the interferences contain errors. In this paper we propose a combined beamspace and element space (CBSES) partial adaptive CRA that is able to maintain a low residual interference and noise level after beamforming, and at the same time, is robust under uncertainties in the estimated characteristics (DOAs) of some of the interferences.