Jointly gaussian approximation and multi-stage LLR combining in the iterative receiver for MIMO-BICM systems

In this letter, we propose a new multi-stage LLR combining (MLC) algorithm in an iterative receiver for MIMOBICM systems. This algorithm combines the soft information from different receive antennas in a multi-stage fashion, where the combining factors are derived based on the joint likelihood function of bivariate Gaussian random variables. The variance transfer (VT) function of the proposed scheme is derived for performance analysis. For slow fading channels, we show that the proposed MLC algorithm can achieve almost the same performance as the linear minimum mean square error (LMMSE) filtering approach, whereas the computation-demanding matrix inverse for LMMSE can be avoided.