I. Introduction
AN important result of the Shannon's celebrated paper [1] is that the source and channel coding operations can be separated without any loss of optimality. This has been the basic idea of enormous research endeavors in separate treatment of source and channel coders. However, in practise, due to strict design constraints such as limited transmission bandwidth, high error protection requirements along with restricted delay and limitations on the complexity of the systems involved, the joint design of source and channel coders has found increasing interest.