An Improved Adaptive Turbo Code And Its Application In The Wireless Transmission Of Images

In 1993, C. Barrou published a famous and important paper about Turbo code,undrawing prelude of researching Turbo code. Turbo code can approach the Shannon limit,which arouses forceful influence in coding theory. Turbo code is the most importantresearch development form the information theory proposed, which leads to zealousresearchers on Turbo coding technique in the communication system.This thesis investigates some problems of Turbo codes with emphasis on the problemof adaptive modulation and Turbo coding. Firstly, adaptive modulation and Turbo codingmodel and wireless channel model are presented. Secondly, adaptive modulation and Turbocoding is lucubrated in coding rate, stopping criterion of iterative decoding and time delay.A new lowering coding rate scheme is presented, a stopping criterion of iterative decodingis improved, and the simulation results and performance analysis are presented. Finally,based on the above Turbo code research, a new adaptive modulation and Turbo codingadding ARQ (Automatic Repeat Request), two iterative decoding schemes are presented,and the best scheme will be selected by simulation results. This new scheme will becompared with threshold method, and the simulation results and performance analysis arepresented. Simulation results prove that this scheme has conquered the threshold method'sdisadvantage of not satisfying time-varying channel, and the correlated results are obtained.The results play an important role in the designing of real communication systems.