An Accurate Analytical Model for Overloaded DS-CDMA under Imperfect Synchronization

A DS-CDMA system is said to be Overloaded if the number of users supported is more than the spreading factor N. Overloading is an attractive candidate for next generation cellular telephony that calls for a higher user capacity than that supported by conventional DS-CDMA systems. This work derives an accurate analytical model for Overloaded DS-CDMA system under imperfect synchronization. The Model also takes care of the degradation in signal energy due to the loss in Autocorrelation value at the matched filter receiver. BER expressions for Individual users are also derived for uniformly distributed synchronization errors that happen to be the case in practical scenario. Monte-Carlo simulations verify the presented analysis.