EXIT-chart-based LDPC code design for spatial modulation

The low-density parity-check (LDPC) code optimization for spatial modulation (SM) is studied using the extrinsic information transfer (EXIT) chart technique. First, for the maximum a posteriori probability (MAP) detector of the SM, its EXIT chart is characterized through Monte Carlo simulations. Then, the optimized degree distribution is acquired by matching the check node decoder curve to the combined detector and variable node decoder curve. Simulation results show that these optimized codes have performance gains from 0.3 to 1.3 dB, compared with the regular code and the optimized code for the additive Gaussian white noise channel, in 4×4 and 16×16 multiple-antenna systems.