PERFORMANCE ANALYSIS OF CMA ADAPTIVE ARRAY FOR QAM SIGNALS

Recently, land mobile communication has advanced significantly. In ord er to carry out transmission at higher speeds than ever, the problem o f frequency-selective fading due to multipath propagation must be addr essed. As a remedy, the use of an adaptive array is investigated. Of t hese adaptive arrays, the CMA adaptive array is known to have excellen t interference suppression characteristics. The CMA was originally con ceived for constant-modulus signals. However, from the point of view o f efficient frequency use, the characteristics of the CMA for signals of nonsteady modulus such as 16 QAM signals have been recognized and o perating examples have been reported. However, to date no discussion h as been reported as to the excellent operation of the CMA for QAM sign als. In this paper, by using the two-wave model, an operation analysis (multipath suppression and convergence) of the CMA for QAM signals is carried out theoretically. Also, computer simulation is carried out t o verify the validity of the theoretical analysis. (C) 1997 Scripta Te chnica, Inc.