Research Of Joint Source And Channel Coding

For the past 50 years,the field of communications has developed under the assumption that the two basic components of the communications problem can be performed independently with no performance degradations relative to joint design. Briefly,this idea,known as the "separation principle",states that "source coding" and "channel coding" can and should be performed independently. By dividing a single difficult problem into two simpler problems,the separation principle has led to 50 years of enormous advances in communications theory and technology. Examples of technologies made possible by communications advances include CD ROMs,fast modems,wireless communications systems,and the Internet. The separation principle is both extremely powerful and extremely limiting to the advancement of communications technology. With the development of modern communication,some systems will lead to the violation of the separation principle,such as resource constraints,multiuser system or time-varying networks. For such systems,performance improvements may be achieved by moving from separate design and operation of source and channel codes to "joint source and channel code" design and operation.In this thesis,we review the joint source and channel coding firstly,introducing fundamental theories,design methodologies,and practical applications. Secondly,an approach is presented for improving arithmetic coding by embedding hamming distance. The approach prevents error propagation of the arithmetic coding. Thirdly,a scheme of layered coding is proposed,which can be applied for rate-varying systems. Finally,the areas for further research are pointed out.