Power-constrained bandwidth-reduction source-channel mappings for fading channels

We consider the transmission of a memoryless Gaussian source over a power-constrained Rayleigh fading channel with additive white Gaussian noise. We propose the use of low-delay joint source-channel mappings and consider optimizing the non-parametric mappings through an iterative process. A design algorithm for joint source-channel mapping is proposed and numerically evaluated for 2:1, 3:1, and 4:1 bandwidth reductions. Parametric mappings are also studied. We assume three cases of fading knowledge; in the case of presence of channel state information at both encoder and decoder, optimal power allocation is solved for the parametric mappings in terms of fading gains and average power constraint. It is shown that the proposed non-parametric and parametric mappings, which have a non-linear structure, achieve a graceful and robust performance and considerably surmount the saturation effect of linear systems.