Challenges in Coding for Quantized MIMO Systems

This paper provides analysis of binary space-time block codes with optimum decoding for multi-input multi-output (MIMO) systems with one-bit receive signal quantization. Exhaustive investigation of short binary space-time block codes with unity code rate shows some remarkable results. For instance, almost all codes perform poorly, except one optimum channel-dependent code which can achieve large coding gain. There are no binary 2×2 space-time block codes (including the Alamouti codes) which can achieve transmit diversity without some channel knowledge. However, there exist a few semi-universal codes which are optimum for almost all MIMO channels and can be selected by feedback from the receiver. Design of longer and more powerful codes remains a challenge and requires further research activity.