Low-Delay Digital and Hybrid Digital/Analog Schemes for Wyner-Ziv Problem Over Gaussian Broadcast Channel

We consider practical low-delay coding schemes for the lossy transmission of a Gaussian source over a Gaussian broadcast channel with two receivers in the Wyner-Ziv setting. One digital scheme and one hybrid digital/analog (HDA) scheme are proposed. Both schemes combine layered coding and dirty paper coding (DPC) at the transmitter. The digital scheme uses layered coding where the common layer information is intended for both receivers while the refinement layer is destined only for the receiver with better quality. Instead of just superimposing the two layers, we propose a bit-filling procedure based DPC to transmit these two layers. A modified log-likelihood ratio based belief propagation algorithm improves the successive canceling procedure with the help of side information. If the refinement-layer decoding decision fails, a typical set-based decoding algorithm is introduced. The proposed HDA scheme superimposes not only the digital information, but also the analog information, quantization error, at the encoder with DPC. Accordingly, we present a scoring-typical set-based decoding algorithm that includes the minimum mean square error estimator for the analog component. Simulation results show that the proposed schemes exhibit performance improvements, and the distortion is shown to be reasonably low for very short block length. Finally we extend the proposed schemes to the three-users case to validate their superiority in the general case.