Multiple antennas and multiuser detection in high data rate CDMA systems

We investigate the use of multiple antennas in the downlink of a high data rate (HDR) system where the base station transmits to a single user at a time on 16 CDMA channels. Multiple transmit antennas allow for space-time spreading (STS), a code-conserving technique for achieving transmit diversity. They also allow for increased spectral efficiency if independent data substreams are transmitted from different antennas using the same spreading code. This latter technique, sometimes known as Bell Labs Layered Space-Time (BLAST) transmission, requires multiple receive antennas and multiuser detection to spatially resolve the mutually interfering signals. In this paper we show how BLAST transmission can achieve transmit diversity using STS. We combine link level and system level simulations to study the potential increase in achievable data rates in a cellular HDR system using combinations of BLAST, STS and space-time multiuser detectors.