Rapid and stable optimization of CMA adaptive array by Marquardt method

The authors present a rapidly converging and well-conditioned algorithm based on the nonlinear least squares method referred to as the Marquardt method for the CMA (constant modulus algorithm) adaptive array. Computer simulation with a pi /4-shifted QPSK (quadrature phase-shift keying) signal verified its rapid and stable convergence characteristics for any radio environment. Taking into consideration the increase of computation for one weight update, the Marquardt method can reduce the convergence time by a factor of 10 to 100 compared to the steepest descent method.<<ETX>>