Optimal and suboptimal receivers for maximal-rate root-LDPC codes over MIMO block-fading channels

This paper deals with full-diversity schemes for MIMO systems in a slowly-varying fading environment. We consider LDPC codes expressly designed for block-fading channels (rootcheck LDPC) and we couple them with spatial multiplexing, to show that they achieve diversity gain, unlike traditional LDPC codes. At the receiver, we consider an iterative turbo-like receiver, both with the optimal demodulator and a suboptimal one, based on linear MMSE filtering. To improve the performance of the latter one, a power unbalance between transmit antennas is introduced. Simulation results and semianalytical techniques like EXIT charts show that our optimized schemes do achieve full diversity.