Conjugate Symmetric Constraint Differential Constant Modulus Beamforming Algorithm

Conventional constant modulus beamforming algorithms (CMA) may converge to interference with high probability when signal-to-noise ratio (SNR) of desired signal is low, which would result in severe performance degradation of beamforming methods. In order to above problem, a conjugate symmetry constraints differential CMA (CSC-DCMA) is proposed in this paper. Firstly, the algorithm introduces a novel differential constant modulus cost function. Then according to the special structure of the steering vector of uniform linear array, a conjugate symmetry constraint is given out. Finally, by normalizing input data, the selection of step factor is independent of the input signal power. As a result, the difficulty of selecting step factor is relieved and practicability of the proposed algorithm is improved. Simulation results show that the proposed algorithm is able to maintain good convergence performance at low SNR. Also, the robustness against initial weight vector error and sensor gain and phase error is verified.