Frequency domain equalizer 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 linear frequency domain canceller operates in the spreaded signal in such a way that the interference and noise at its output is minimized (minimum mean squared error criterium). The performance is evaluated in two configurations: one including the frequency shift canceller (FSC) and the other concatenated with parallel interference canceller (PIC). The results are benchmarked against the performance of the conventional RAKE detector and the conventional PIC detector.