A Novel Constrained Adaptive Algorithm Using the Conjugate Gradient Method for Smart Antennas

In this paper, several reported blind adaptive beam- forming algorithms, including the stochastic gradient (SG) methods and the recursive least squares (RLS) methods are reviewed. Then, the conjugate gradient (CG) algorithm is introduced as a tradeoff between SG and RLS algorithms. On the basis of this idea, a novel constrained constant modulus (CCM) design criterion is described and employed for deriving a modified conjugate gradient (CG) optimization algorithm, which does not require the information of the desired user beforehand. Simulations are performed to compare the performance of the proposed method with both SG and RLS methods. The results indicate that the proposed approach has a significant faster convergence rate and superior resolution compared with the SG algorithms and lower computation complexity compared with the RLS algorithms.