Generalized Capacity and Source-Channel Coding for Packet Erasure Channels

We study the transmission of a stationary ergodic Gaussian source over a packet erasure channel, which is a composite channel with degraded states. A broadcast channel code can be applied to a composite channel to obtain different rates in the different channel states. However, we show that a non-broadcast direct transmission strategy achieves a higher expected rate than the broadcast code, although it does not meet Shannon´s definition of reliable communication since it does not guarantee which bits will be received. Each channel code has a matching source code: the multiresolution source code allows the broadcast channel code to transmit prioritized information, and the symmetric multiple description source code enables direct transmission of unprioritized information. The end-to-end expected distortions of these schemes are also compared.