Low complexity BICM demodulation for MIMO transmission

Abstract

In this paper we deliberate on channel coding for spatial data streams and focus on their equal-rate non-uniform power distribution in successive interference cancellation (SIC) detection algorithm. We focus on high spectral efficiency bit interleaved coded modulation (BICM) MIMO OFDM system where, after serial to parallel conversion, per antenna coding and antenna cycling, spatial data streams are simultaneously transmitted by using an antenna array. The reception is based on SIC detection algorithm. Standard receiver solutions for such schemes employ minimum mean square error (MMSE) successive stripping decoders. Application of MMSE filters combined with the Gaussian assumption of post detection interference institutes sub-optimality in the metrics and furthermore these equalizers are intricate in computation. We propose a novel near optimal demodulator based on match filter outputs for a 2 times 2 system which reduces the sub optimality of the metric resulting in an improved performance and a significant reduction in computational complexity with respect to the MMSE based solutions. We further extend the idea to higher-dimensional MIMO systems showing that there is a slight degradation in the performance with increase in dimensionality of the system but is concurrently coupled with a boost in complexity savings.