A cyclostationary receiver for aperiodic CDMA signals

In a long-code/aperiodic direct-sequence code-division multiple-access (DS/CDMA) system, the user spreading sequences span multiple information symbols. Most interference suppression techniques have been proposed for short-code/periodic CDMA systems where the spreading sequence is confined to a single symbol interval and generally cannot be applied directly to a long-code system. In this paper, we investigate a cyclostationary receiver with a parallel architecture that converts an aperiodic CDMA signal into a set of periodic signals, one in each arm of the parallel receiver. Blind interference suppression based on Tikhonov regularization is performed by the cyclostationary receiver for real Interim Standard 95 (IS-95) signals captured inside a building and its performance is compared to that of a conventional matched filter (MF) receiver. The performance of the receiver is improved using blind recursive algorithms and a decision-directed approach.