Interference suppression in CDMA downlink through adaptive channel equalization

Abstract

In the synchronous CDMA downlink using orthogonal spreading codes, the multiple access interference (MAI) is essentially caused by the multipath channel. This is why the MAI can be suppressed by channel equalization. In this paper we present a receiver algorithm which performs adaptive channel equalization by estimating the transmitted chip sequence. The adaptation uses Griffiths' algorithm and converges to the LMMSE solution. The receiver is applicable in systems using long code scrambling such as in the 3/sup rd/ generation wideband CDMA proposals, and it is shown to offer significant performance gains when compared to conventional RAKE receivers.