Multiuser signal design and detection using interference-resistant modulation

Recently developed space-time code has shed new insights in designing signals over multiple transmit antennas. In this paper, by considering a set of independent and synchronized users communicating with the base station in the reverse link, the joint users' signals can be analyzed within the framework of space-time code. As multiuser transmission requires that each user's signal is confined to its own transmitting antenna, co-channel/inter-antenna interference degrades the performance significantly. We propose a novel multiuser signal structure called Interference-Resistant Modulation (IRM) to improve the performance without coding and bandwidth-expansion. We prove that, both analytically and by simulations, the asymptotic performance of IRM with maximum-likelihood detection achieves the single-user performance. Further, to reduce the prohibitive complexity posed by ML detection, we propose a simple MMSE-based pre-combining detector. It is shown that the proposed detector combined with IRM provides sign ificant improvement over previous approaches with the same complexity.