Optimized Design And Performance Simulation Of Turbo Code

Turbo codes are a new class of error-correcting codes that can approach the Shannon limit. It is considered as the most exciting and potentially important development in coding theory in recent years. Its invention has changed the conventional design principles of the coding scheme from the attempt to increase the minimum Hamming distance of the code to the goal of reducing the number of code words with low Hamming weights.This thesis investigates some problems of turbo codes with emphasis on the problem of the selection for constituent encoder in turbo code construction, especially the non-systematic convolutional codes, the performance of turbo codes in a frequency-hopped system, and so on. The main results and contents of this dissertation are as follows:1. The development on the theory and technique of channel coding is outlined; the development and application of turbo codes is also discussed.2. The principle of iterative decoding of turbo codes is illustrated, and the decoding algorithm of turbo codes over AWGN channel is displayed.3. An analysis on the selection of constituent encoder of turbo codes, especially the non-systematic convolutional codes is proposed. After the study on Effective Free Distance and convergence characteristic of encoder, some non-systematic turbo codes with good performance are given.4. The principle and applications of Frequency-Hopped system are discussed. According to the characteristics of AWGN and Rayleigh fading channel, and combining with the Frequency-Hopped system property, the performance of turbo codes is shown.Since turbo codes has excellent performance and become more popular used in communication system and information security system, the study of turbo code is of great significance. The application of turbo code still faces some problems. There are many problems left on the turbo theory which need advanced study. Nowadays, we have little work on this title, and great effort will be done to this problem.