Adaptive Minimum-Distance Based Precoder for NB-LDPC Coded MIMO Transmission

In this paper, we focus on a multiple-input multiple-output (MIMO) linear precoder based on the minimum Euclidean distance criterion, the max- dmin precoder. We propose an optimization of this precoder for the case of an association with a non-binary low density parity check code (NB- LDPC). After recalling the well-known max-dmin precoder, we set forth an optimization of the mutual information of initial message, i.e. I(0), through the extrinsic information transfer (EXIT) analysis of the system. We present a new adaptive precoder whose forms are determined in function of an adaptive threshold angle, optimized in terms of the mutual information I(0), and depending on the signal-to-noise ratio at the reception (SNR_R). The performance of the new precoder is brought out through a theoretical study along with a series of numerical simulations.