Bipolar Chaotic Pulse Position Modulation Communication System Based On LDPC

With the development of communication technology, chaotic digital communication system shows a great value in theoretical research and engineering application and meet the needs of safe, secure communication especially. However, the transmission channel conditions are complex, the noise interference and multi-path effect always reduce the communication quality. The application of LDPC code in chaotic digital communication system will improve the BER performance. In this paper, on the basis of previous research, the chaoic shift keying communication system and chaotic pulse position modulation system were studied, the LDPC code was applied to the improved scheme, and some useful conclusions were obtained.Firstly, the definition, characteristic, description parameters and application potential of chaos were introduced. Methods to generate discrete chaotic sequence and analysis the characteristics of chaotic signal were studied. The classification of chaotic communication system were introduced.Secondly, the chaos communication systems based on shift keying were discussed at first. Then, the DCSK system built by DSP Builder platform were given, the simulation results in Simulink and Model Sim were compared.Once more, the CPPM communication system were studied at first, and the time division multiple access scheme for CPPM was discussed. Then a new scheme named BCPPM was proposed, and the BER performance of the above two schemes was compared in Matlab.Finally, the basic theory of LDPC code was introduced at first. Then, the performances of the different three decoding algorithms were compared in simulation by Matlab. Turned the LDPC code into the BCPPM scheme and verified the BER performance increment after simulation.The innovation of this paper is mainly at using the DSP Builder to build the DCSK system and comparing the simulation results from Simlink and Model Sim, the proposed bipolar chaotic pulse position system, using the cyclic-LDPC code into the proposed BCPPM to improve BER performance.