Transmit Diversity for Combined 2G and 3G CDMA Systems

In this memo, we propose modifications to existing transmit diversity techniques to provide transmit diversity in CDMA cellular systems which must support both second generation and third generation mobiles. The proposed method, which we call symmetric sweep transmit diversity, combines Phase Sweep Transmit Diversity (PSTD) and Space-Time spreading (STS) in a way that allows second generation mobiles to obtain the full advantage of PSTD while third generation mobiles obtain the full advantage of STS.