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 sourcechannel 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.