Multi-sensor frequency domain multiple access interference canceller for DS-CDMA systems

Abstract

Direct Sequence Code Division Multiple Access (DS-CDMA) signals exhibit cyclostationary properties which imply redundancy between frequency components separated by multiples of the symbol rate. In this paper a Multiple Access Interference (MAI) Canceller (Frequency Shift Canceller (FSC)) that explores this property is presented. The linear frequency domain canceller operates on the spreaded signal so as to minimise the interference and noise at the output (Minimum Mean Squared Error Criterium). The performance of multi-sensor configurations for the cases of beamforming and uncorrelated spatial channels was evaluated considering both synchronous (UMTS-TDD) and time misalignment systems. The FSC configurations were concatenated with 2D-PIC structure and evaluated. The simulation results show considerable improvement relative to the conventional 2D-RAKE and 2D-PIC receiver. A performance close to the single-user RAKE case was achieved when it was evaluated jointly with 2D-PIC.