Detectors and Asymptotic Analysis for Bandwidth-Efficient Space–Time Multiple-Access Systems

Detectors and Asymptotic Analysis for Bandwidth-Efficient Space–Time Multiple-Access Systems In this paper, a narrowband multiple-channel transmission scheme with multiple transmit antennas is proposed and analyzed. The channelization is based on space–time signature matrices, which do not expand bandwidth, unlike conventional schemes such as code-division or time-division multiplexing (CDM or TDM). The channels can be used by multiple independent users in an uplink or downlink scenario (multiple access or broadcast channels, respectively), or by one user in a multiplexing scenario. The data transmitted on each channel is convolutionally encoded, interleaved, and then space–time block encoded before space–time channelization. Each channel has a unique interleaver and space–time signature, but the convolutional encoder and space–time block code can be identical across channels. It is shown that asymptotic single-user-like performance can be achieved with optimal detection and decoding, in a Rayleigh fading channel. Practical receiver algorithms are developed based on the iterative (turbo) detection technique. The simulation results demonstrate that these suboptimal receivers achieve single-user performance at moderate signal-to-noise ratios and moderate user loads. In the single-user multiplexing case, a significant performance gain over single-channel transmission with the same data rate is obtained.