Frequency shift based multiple access interference canceller for DS-CDMA systems

Abstract

The cyclostationary properties of direct sequence spread spectrum signals are well known. These cyclostationary properties imply a redundancy between frequency components separated by multiples of the symbol rate. We present a multiple access interference canceller that explores this property and applies it to UMTS-TDD. This frequency domain canceller acts on the spread signal in such a way that minimizes the interference and noise at its output (minimum mean squared error criterium). The performance is evaluated in two detector configurations: one including the frequency shift canceller (FSC) and the other plus a parallel interference canceller (PIC). The results are benchmarked against the performance of the conventional RAKE detector and the conventional PIC detector.