Improvement And Analysis Of Differential Chaos Shift Keying Communication System

Chaos communication is a new field of communication technologies, to which chaos will be applied. It has short history of the development, but really has a good communication quality and performance. Chaos is a spread spectrum signal which has sensitivity to initial conditions, seemingly random behavior, continuous power spectrum of broadband, low cross-correlation properties and other characteristics. Moreover, it can be produced by a simple circuit, so that the transmitter and the receiver could decrease the cost. These features make the chaotic characteristic has broad application prospects in the field of communication. Present study showed that chaos can be used to achieve high-quality and high-performance communications, so, the chaos is very necessary to be used for the field of communication.This paper describes the development history of chaos and chaos communications, research and application of research at home and abroad as well as the main problem. Then, the theoretical basis of chaos theory is elaborated, including the definition, characteristics, generation of chaos, chaotic model and its common characteristics. After that, several shift keying communication systems are compared where the advantages and disadvantages are given. The bit error rates of two important shift keying communications, CSK and DCSK, are analyzed in Gaussian White Noise channel.Finally, in this paper, a diversity reception and inverting demodulation scheme for DCSK in Rayleigh multipath fading channels was proposed by drawing lessons from the diversity reception technology and inverting demodulation technology, then making its theoretical analysis and performance simulation in Rayleigh and Rice multipath fading channel. In the scheme, transmitting signals are delayed appropriately to generate multi-channel signals. After each signal adding up, the result is inverted by correlative operation. And the receiving end made decisions according to the calculation result. Theoretical analysis and simulation results indicate, compared with the original DCSK communication system, DCSK communication system based on the diversity reception and inverting demodulation scheme made some improvement that the BER performance of this scheme satisfied demands far better. Also, it can effectively suppress noise.