Linear precoders for multiuser MIMO for finite constellations and a simplified receiver structure under controlled interference

This paper is an extension to the earlier proposed idea of exploiting the discrete constellation alphabets in linear precoding for the downlink of multiuser (MU) MIMO. In the earlier work, it was shown that the transmission of controlled interference to the users bears the potential of exploiting the interference structure in improving the error resilience. In this paper we propose a linear precoding strategy for the downlink of multiuser MIMO on the idea of controlled interference. However under the controlled interference, intuitive optimal receiver is Maximum Likelihood (ML) detector which would require an exhaustive search of the controlled interferers. It would have exponential search complexity in the number of users and their constellation sizes. We further propose in this paper a simplified receiver structure which exploits the interference structure by ML detection but its complexity is equivalent to that of a receiver that confronts no interference (in two user case). Monte Carlo simulations show the improved performance of the proposed linear precoding strategy relative to the existing linear precoding schemes.