A Design for an EXIT Chart-Aided Adaptive Transmission Control Technique for Single-Carrier Based Multi-User MIMO Systems

This paper proposes a scheduling and adaptive rate control scheme for multi-user multiple-input multiple-output (MIMO) systems in the uplink, designed to improve system throughput in single-carrier broadband wireless systems with a turbo equalizer. In the proposed scheme, to reduce computational burden for the scheduling and adaptive rate control, scheduling including stream selection is first conducted in the base station (BS) based on the expected signal to noise power ratio (SNR) after the turbo algorithm is converged. The BS also conducts coding rate optimization for each scheduled stream while convergence for the turbo equalizer is guaranteed thereby maximizing throughput efficiency. In order to guarantee the convergence property, this paper also proposes a rate control scheme suitable for the turbo equalization using an extrinsic information transfer (EXIT) trajectory which is predicted only from channel transfer functions. Computer simulation confirms that the achievable average system throughput can be significantly improved with the proposed scheme.