Simulation And Research On Turbo Trellis Coded Modulation

In 1982, Ungerboeck proposed trellis coded modulation (TCM) scheme, and broke the traditional independent mode of encoder and modems. The advantage of TCM scheme is that it can win excellent decode performance without increasing system bandwidth and reducing the speed of data transmission. TCM scheme bases on convolution codes. So when Turbo codes were put forward as a new channel coding method whose performance is close to the Shannon theoretical limit in low SNR, it became the best choice of TCM scheme. The schemes of Turbo codes combined with different higher-order modulation are called Turbo trellis coded modulation, notes for Turbo-TCM or TTCM.Since the technology of TTCM was put forword, its specific realization schemes have aroused many people's keen interest. On the basis of further study in codec structure and implementation principle of Turbo codes and TTCM scheme, the thesis simulates Turbo codes and TTCM scheme in gauss channel with computer simulation by the technology of Matlab 2008a and VC++ 2008 mixing programming, and analyses the results.This thesis mainly includes the following aspects:First, in VC++ 2008 and Matlab 2008a environment, the thesis research specific realization principle and method of mixing programming, which is applied to the thesis simulation to improve simulation efficiency. Secondly the thesis realize the performance simulation of binary Turbo codes decoding by the technology of mixing programming. The simulation results verify that Turbo codes can get decode performance close to Shannon theory limit in low SNR. Finally, on the basis of Turbo codes research, this thesis mainly studies TTCM scheme and achieves the codec simulations of TTCM combined with 8PSK modulation and 16QAM modulation by mixing programming technology of VC++ 2008 and Matlab 2008a. This thesis gave the simulation results of TTCM decode performance with different iterations, different frame lengths and different ways to modulation symbols mapping. The simulation results verify that the effectiveness of TTCM scheme in both improving traditional TCM system error correction performance and improving spectrum utilization efficiency.