QAM with interference cancellation for high-speed multicode CDMA

The potential of multi-level modulation for forward link of multicode CDMA systems with interference cancellation to support high data rate service is studied. In third generation (3G) CDMA systems, multicode and/or multicarrier modulation schemes are used to support high data rate service, meanwhile, quadrature amplitude modulation (QAM) is a more promising candidate for transmission of even higher rate data due to its high spectrum efficiency. In this paper, the BER performance of the M-QAM WCDMA system with interference cancellation is evaluated. Numerical results show that a M-QAM wideband CDMA system is more sensitive to the channel estimation error. Moreover, with high quality channel estimates, 16-QAM or 64-QAM with multicode interference cancellation in the WCDMA system is more attractive to increase the system capacity.