Consideration on performance of the CMA adaptive array antenna for 16 QAM signals

The CMA adaptive array was developed for capture of constant modulus signals. As is well known, the CMA adaptive array can suppress interferences successfully under multipath environments. In order to investigate the availability of CMA adaptive array for other non-constant modulus signals, this paper deals with performance of the CMA adaptive array for 16 QAM signals which have high bandwidth efficiency. Several CMA-based cost functions modified for the QAM signals are introduced and also an algorithm of switching those cost functions in the process of adaptation is proposed. Via computer simulation, it is shown that the CMA adaptive array with the cost functions changed in adaptation has significantly better convergence characteristics for the 16 QAM signals. In addition, the BER performance of the cost functions is clarified