Joint Source-Channel Coding at the Application Layer

The multicasting of an independent and identically distributed Gaussian source over a binary erasure broadcast channel is considered. This model applies to a one-to-many transmission scenario in which some mechanism at the physical layer delivers information packets with losses represented by erasures, and users are subject to different erasure probabilities. The reconstruction signal-to-noise ratio (SNR) region achieved by concatenating a multiresolution source code with a broadcast channel code is characterized and four convex optimization problems corresponding to different performance criteria are solved. Each problem defines a particular operating point on the dominant face of the SNR region. Layered joint source-channel codes are constructed based on the concatenation of embedded scalar quantizers with binary raptor encoders. The proposed schemes are shown to operate very close to the theoretical optimum.