Acknowledgment of 3GPP WCDMA random and packet access applying space-time transmit-diversity

Advanced packet-access based services are now widely considered to play the key role in 3/sup rd/ generation (3G) mobile communication systems. The FDD-mode (commonly denoted as WCDMA) standardized by the 3/sup rd/ Generation Partnership Project (3GPP) provides a variety of logical, transport and physical channels to assist efficient packet based transmission. Random access channel (RACH) and common packet channel (CPCH) are reverse link (packet) channels that are shared among several users. So-called acquisition indicator channels (AICH) are used with RACH and CPCH on the physical layer to assist fast acknowledgment of (packet) access grants or rejections. Space-time transmit diversity (STTD) is the WCDMA concept for performance improvement of forward link, nonpower-controlled, physical channels like AICH. This paper describes the RACH and CPCH concept with emphasis of the AICH. It introduces the STTD concept for AICH and shows link layer performance results with and without applying STTD.