Both Deterministic Interleaver Research And Improvement

Turbo code is a new class of error-correcting codes that can approach the Shannon bound. 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 low weight distribution and two deterministic interleavers. The main results and contents of this dissertation cover the follows:1. The development of the theory and technique of channel coding are outlined; the development and application of turbo codes are also discussed.2. The low weight distribution of turbo codes is illustrated, and some methods which calculate the low weight distribution are described.3. The types of the interleaver is illustrated, the algorithms of a few deterministic interleavers are expatiated particularly.4.Based on the quadratic congruence interleaver ,a new algorithm which is improved on the linear congruence is advanced , the choices of its parameters are analyzed systematically and The new algorithm has the effects on the low weight codewords distribution.5. In the 3GPP interleaver, a new scheme for optimal energy allocation based on the distribution of low weight codewords which allocates energies to the different codewords that have different weights is employed. By employing this scheme, the improvements for the BER are very apparent for the higher Eb/NO.