Mean convergence rate of a decision directed adaptive beamformer with Gaussian interference

New analytic results on the convergence of a blind decision directed adaptive algorithm in a beamforming application are presented. The data received at multiple antennas is assumed to consist of a desired PSK signal plus additive Gaussian noise and interference. The mean improvement in output SINR obtained with one iteration of the adaptive algorithm is predicted. This is used to estimate the number of iterations required for convergence. Results are presented for BPSK and QPSK signals. The performance of the decision directed algorithm and a constant modulus algorithm is also compared.