STTC-SD with LMMSE multi-user detection for WCDMA downlink

In this paper we analyze the performance of Space Time Trellis Coded-Scrambling Diversity (STTC-SD) scheme for WCDMA downlink, when a linear minimum mean squared error multi-user detection (LMMSE-MUD) receiver is used. STTC-SD scheme for CDMA systems was introduced in [1, 2] and was shown to perform better than conventional STTC scheme under low system loads. At high system loads, the STTC-SD scheme suffers excessively from multiple access interference. In this paper we show that, by using a LMMSE-MUD receiver, this problem can be rectified so that STTC-SD scheme performs significantly better than standard STTC scheme at all system loads.