The Design And Simulation Research Of Chaotic 4-ary Digital Communication System Based On Hamilton Oscillator

Benefiting from its characteristics of aperiodicity,broadband,unpredictability and easy to produce,chaotic signal is widely used in communication area.Usually,the security of chaotic communication system is better than traditional digital communication system.However,the information transmission efficiency and bit error rate of chaotic communication system is inferior to common communication system,which also causes the stagnation of the research.The lack of breakthrough in chaos synchronization technology also hinders the applicaton of chaotic communication into practical engineering interest.The assessment of the quality of bit error rate of chaotic communication system is mainly depended on the type of chaotic mapping.Choosing appropriate chaotic mapping can greatly improve the quality of bit error rate of chaotic communication system.Given the information transmission efficiency,the research on chaos binary communication research is more common than chaos M-ary communication.At present,the research trend of chaotic communication is in two directions.The first direction is achieving the breakthrough of chaos synchronization technology and the continuous study on traditional chaotic secure communication.Along with the rapid development of chaotic theory,the second research direction is also emerged,which by searching new chaos oscillator for chaos communication will provide new area and realization scheme for chaos communication theory.Studying from the second research direction mentioned above,this dissertation inquires into the application of Hamilton oscillator in chaos 4-ary communication in order to improve the quality of bit error rate and information transmission efficiency.Based on the method of Hamilton chaotic M-ary modulation and demodulation mentioned in literature[107],this dissertation discusses the main technological problems of the application of Hamilton oscillator into chaotic 4-ary communication system,especially the design problems of Hamilton chaotic baseband demodulator in different noises and chaos Hamilton 4-ary communication system based wireless transmission.The main works of the dissertation are as follows:(1)In order to improve the information transmission efficiency of the present Hamilton chaos 4-ary communication system,this dissertation studies the problem of saving the bandwidth of chaotic modulated signals in wireless transmission.It also designs the 4-ary communication system which transmit Hamilton baseband information in Nyquist rate based on QAM RP modulation.The system makes the two way Hamilton modulated signals into one way for information transmission through Quadrature Amplitude Modulation,compared with AM modulation,it not only reduces the quantity of channel,but also improves the information transmission efficiency and the utilization ratio of bandwidth.By constructing the Hamilton chaos 4-ary communication system,it solves the problems of carrier recovery、the phase tracjectory reconstruction of Hamilton oscillator、the realization of zone partition detector、the problems of symbol synchronization recovery,the simulation results is given.Finally,it discusses the feasibility and the complexity of Hamilton chaos 4-ary communication system.By using the platform of FPGA,it realizes the Hamilton chaos baseband 4-ary modulation and demodulation module,besides,the test results and hardware design of Hamilton chaos 4-ary communication system by combining existing RF chip is given.(2)Given that Hamilton baseband demodulator is vulnerable to channel noise,this dissertation researches on the the boundary range of zone partition demodulator in white nosie and color noise,and two methods about the analysis of signal to nosie rate(SNR)with the roughness of Hamilton modulated signals’ phase trajectory are proposed in this dissertation,then the boundary fomula of zone partition demodulator is given.Firstly,based on Hamilton chaos QAM 4-ary communication system,the phase trajectory influence of Hamilton modulated signals in additive white Gaussian nosie(AWGN)channel is studied,the mathematical analysis of the probability density function of chaos demodulating signals in white noise is given,then the boundary range of zone partition demodulator is given through confidence area.Secondly,the curve fitting method is given,it also suitable for non-Gaussian noise.Finally the validity is verified in the simulation.(3)In order to given the realization of whitening filter based on Hamilton chaos 4-ary communication system,the solution to the color noise is using pre-whitening in the transmitter and pre-distortion technologies in the receiver to construct communication system.The construction problem of Hamilton chaos 4-ary communication system in additive color Gaussian noise channel is studied.The whitening process of additive color Gaussian noise is studied first,the main modules of anti color noise Hamilton chaos 4-ary communication system are constructed,such as pre-distortion,whitening,up and down convertion,zone partition demodulator and symbol synchronization circuit.The simulation result shows that the proposed system has anti color noise performance.In the final part,the future research and unsolved problemin this dissertation is elaborated.