Threshold of LDPC coded BICM for Rayleigh fading: density evolution and EXIT chart

In this paper we focus on the threshold computation and convergence analysis of regular LDPC coded BICM for Rayleigh fading channels. We compute the decoding threshold using discretized density evolution with and without channel state information. The convergence properties of DE are analyzed using extrinsic information transfer (EXIT) chart. The key parameter, the power correlation coefficient is identified and threshold degradation is quantified when perfect CSI is not available at the receiver. The optimal energy allocation between pilots and coded symbols is found to be sensitive to the normalized Doppler spread of the channel, the interpolation filter, modulation schemes and the pilot selection.