Exact BER Performance of Asynchronous DS-CDMA Systems using Quadriphase Spreading and QPSK Modulation over Rayleigh Channels

摘要

An accurate closed-form expression is derived for calculating the average BER in an asynchronous DS-CDMA system using random complex-valued spreading sequences for transmission over Rayleigh channels. This accurate solution is based on the Characteristic Function (CF) approach and only requires a single numerical integration. Our numerical simulation results verify its accuracy, and also demonstrate the relative inaccuracy of the Gaussian approximation.