AN IMPROVEMENT IN THE PERFORMANCE OF DS SS/CDMA WITH GMSK/

The CDMA system using DS/SS/GMSK modulation can realize a high spectra l efficiency by using the constant-envelope property of GMSK modulatio n, even if the signal is band-limited and the transmitter is nonlinear . This paper discusses the optimization of a receiver in order to furt her improve spectral efficiency. The idea is to apply optimal weights to the despreading matrix. Using the signal-to-noise power ratio based on a linear approximation to the DS/SS/GMSK waveform, the weights tha t minimize the signal-to-noise power ratio are determined. The perform ance is compared to that of the conventional receiver, in terms of the signal-to-noise power ratio after despreading, the bit error rate, an d the spectral efficiency. As a result, we show that performance is im proved by applying optimal weights to the despreading matrix. (C) 1998 Scripta Technica.