Frequency shift based multiple access interference canceller for multirate UMTS-TDD systems

Direct sequence spread spectrum (DS-SS) signals exhibit cyclostationary properties which imply a redundancy between frequency components separated by multiples of the symbol rate. In this paper we present a multiple access interference canceller that explores this property and applies to UMTS-TDD This frequency domain canceller operates in the spreading signal in such way that the interference and noise at its output is minimized (minimum mean squared error criterion). The performance is evaluated in two configurations: one including the frequency shift canceller (FSC) and the other concatenated with the parallel interference canceller (PIC). The results are benchmarked against the performance of the conventional RAKE detector and the conventional PIC detector.