Iterative Decoding of Multiple Descriptions

This paper considers the transmission of multiple descriptions over noisy channels rather than the on-oo channels that are traditionally considered. We introduce the use of iterative decoding techniques similar to those used in \turbo" decoding to decode multiple correlated descriptions transmitted over a noisy channel. For a given transmission rate per channel and a given channel state, the eecacy of iterative decoding depends on the correlatedness of the two descriptions produced by the multiple description encoder. We demonstrate that there is an optimal amount of redundancy or correlation for a given channel state. Hence, multiple description codes may also be viewed as joint source-channel codes.