Multi level Multiple Descriptions

Multiple Description (MD) source coding is a method to overcome unexpected information loss in a diversity system such as the internet, or a wireless network. While classic MD coding handles the situation where the rate in some channels drops to zero temporarily, thus causing unexpected packetloss, it fails to accommodate more subtle changes in link rate such as rate reduction. In such case, a classic scheme can't use the link capacity left for information transfer, causing even minor rate reduction to be considered as link failure. In order to accommodate such a frequent situation, we propose a more modular design for transmitting over a diversity system, which can handle unexpected reduction in link's rate, by downgrading the original description into a more coarse description, so it would fit to the new link's rate. The method is analyzed theoretically, and performance results are presented.