Hybrid digital-analog joint source-channel coding for broadcasting correlated Gaussian sources

We consider the transmission of a bivariate Gaussian source S = (S1, S2) across a power-limited two-user Gaussian broadcast channel. User i (i = 1, 2) observes the transmitted signal corrupted by Gaussian noise with power σi2 and wants to estimate Si. We study hybrid digital-analog (HDA) joint source-channel coding schemes and analyze these schemes to obtain achievable (squared-error) distortion regions. Two cases are considered: 1) source and channel bandwidths are equal, 2) broadcasting with bandwidth compression. We adapt HDA schemes of Wilson et al. [1] and Prabhakaran et al. [2] to provide various achievable distortion regions for both cases. Using numerical examples, we demonstrate that for bandwidth compression, a three-layered coding scheme consisting of analog, superposition, and Costa coding performs well compared to the other provided HDA schemes. In the case of matched bandwidth, a three-layered coding scheme with an analog layer and two layers, each consisting of a Wyner-Ziv coder followed by a Costa coder, performs best.