Differential space-time modulation schemes for smart antenna aided generalized multicarrier DS-CDMA systems

Differential space-time modulation (DSTM) schemes were proposed for detection without any knowledge of the channel state information (CSI), which is an attractive feature in the presence of fast fading channels, where accurate channel estimation is a challenging task. In this contribution we invoke two DSTM schemes for improving the achievable performance in the downlink of a generalized MC DS-CDMA system employing smart antennas, namely the differential space-time spreading (DSTS) scheme and the differential steered space-time spreading (DSSTS) scheme. In the MC DS-CDMA system considered the transmitter employs multiple antenna arrays and each of the antenna arrays consists of several antenna elements. Furthermore, the generalized MC DS-CDMA system employs both time- and frequency (TF) domain spreading, where a user-grouping technique is employed for reducing the effects of multiuser interference