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Keywords:

  • blind beamforming;
  • array processing;
  • adaptive signal processing;
  • multipath receivers

Abstract

The constant modulus algorithm (CMA) is a popular and effective method for blind adaptive beamforming in various wireless communication systems. Traditionally, signals of arrival are considered to be independent. However, multipath propagations in wireless systems often results in several correlated signal arrivals. Because of multipath arrivals, CMA beamformers cannot be expected to place nulls in the direction of all interferers as assumed in some existing beamforming. In this paper, we present a simple convergence analysis of CMA under multipath correlated arrival signals. We propose two adaptation techniques based on CMA to capture different source signals. One approach is to use an orthogonal projection constraint on the beamformer parameters. The other approach relies on the independence of source signals and exploit a Gram–Schmidt orthogonalization at beamformer outputs. Both methods are tested through computer simulations. © 1998 John Wiley & Sons, Ltd.