The Matlab Implementation Of Joint Source And Channel Decoding Of Turbo Code Based On Meanmatch

The so-called joint source and channel encoding, as the name suggests, is a encoding scheme with comprehensive consider on the factors of source and channel. Its main purpose is to make the design and implementation of communication system more simple and economic under the guarantee of the reliability and effectiveness.The thesis focuses on a branch of joint source and channel encoding: joint source and channel decoding. The implementation of joint source and channel decoding requires two conditions: the source own redundancy and decoding-end should be able to use this redundancy to guide decoding. The digital image is selected as a source of information to meet the first condition and Turbo code with iterative decoding is used in decoding-end to fulfill the second condition. At first, this thesis introduces the profile of joint source and channel encoding. Secondly, the thesis compares the basic principles of traditional coding/decoding methods and joint source and channel encoding, then focuses on the basic idea of joint source and channel decoding, and introduces the basic characters of digital image. Thirdly, the principle of Turbo code/decode is introduced. The Turbo code can resist to noise by guiding decoding with the redundant of image source, because of its character of iterative decoding. After that, the thesis proposed a method of Turbo code joint source and channel decoding based on mean match, and then introduced its basic idea and the principles of two main modules: error detection and operation of weight. Finally, the modules of the error detection and operation of weight are implemented in MATLAB, and then the thesis simulates and compares the performance of the joint source and channel decoding and the traditional coding/decoding. The idea of doubt and second doubt is put forward in error detection module. In the modules of weight operation, the thesis does the comparative simulation of multiply modify and plus modify. Then compares the performances of fixed and variable modify of the plus modify scheme on conditions of different bit, different iterative, different SNR.The results show that,the performance of Turbo code joint source and channel decoding based on the mean match is much better than that of the ordinary decoding method in a certain extent SNR.