EXIT Chart Analysis Aided Turbo MUD Designs for the Rank-Deficient Multiple Antenna Assisted OFDM Uplink

Abstract

In this paper, the mutual information transfer characteristics of several novel turbo multiuser detectors (MUD) employed in space division multiple access (SDMA) aided orthogonal frequency division multiplexing (OFDM) systems are investigated with extrinsic information transfer (EXIT) charts. These novel schemes are the Bayesian, the Soft Interference cancellation aided minimum bit error rate (SIC-MBER) and the reduced-complexity minimum Bit Error Rate (RMBER) turbo MUDs. In order to increase the effective throughput of the system, a powerful MUD has to be employed in the so- called "rank-deficient" scenario, namely when the number of transmit antennas exceeds that of the receiver antennas. The classic minimum mean square error (MMSE) solutions exhibit a low complexity. However, they are overwhelmed in rank-deficient scenarios. In these situations powerful non-linear MUDs are required, which are designed in this treatise.