Fast converging CMA-aided maximum a-posteriori algorithm with a conjugate symmetric constraint for adaptive blind beamforming

Abstract

This paper investigates constant modulus algorithm-aided maximum a-posteriori algorithm (CMA+MAP) for adaptive blind beamforming based on the uniformly linear array structure. Under the assumption of the blind beamformer outputs geometrically near the optimal samples, we first contribute to deriving a closed-form optimal solution of the blind MAP algorithm. A conjugate symmetric property is further acquired for the optimal expression of the blind MAP. The additional information on conjugate symmetry is then incorporated into the CMA+MAP algorithm to develop a novel adaptive blind beamforming. Compared to the classical and state-of-the-art blind methods, this novel blind beamformer has shown in simulations to be more robust to the ambiguous decision, error propagation and real-time scenarios where only few snapshots for adapting are allowed. Keywords-Adaptive blind beamforming, constant modulus algorithm (CMA), maximum a-posteriori (MAP), uniform linear array (ULA).