Research On FM-DCSK Based Chaotic Communication System

With the fast development of science and technology, the convenience of wireless and mobile communication makes it more appealing and widely applied. However they are inevitably impaired by fading especially multipath fading through wireless radio transmitting signals. In the conventional communication, compensative techniques like rake reception are introduced to resist such fading. The estimation of channel is necessary under the situation, but it's not easy to ensure the accuracy of estimation. Chaos communication, namely chaotic modulation & demodulation (FM-DCSK) with no need for knowledge of the channel, in some sense, provides a brand new and simple solution for fading problem, thus holding special attention from the academics.Chaos communication is different from the conventional communication in that the former applies a chaotic modulation. A non-periodic chaotic signal serves as the carrier and the application of non-coherent demodulation free it from the synchronization problem of chaotic carrier thus making it possible for realization. A chaotic signal is a pseudo-random sequence sensitive to the initial value, which has a broad spectrum like a white noise. What's more, a chaotic signal has good performance of both auto-correlation and cross-correlation. All the characteristics above enable a chaotic signal competent as a carrier in digital modulation, and chaotic modulation has a hybrid function of conventional spread spectrum and modulation, thus having a potential capability of anti-multipath fading. Together with the simplicity of a chaotic signal generation, it's easy for implementation and popularization. The Chaos modulation technology is really a promising one for wireless and mobile communication systems.The work of this paper focuses on FM-DCSK, which has offered the best robustness against multipath fading under channel imperfections so far. Through investigation, design and simulation, we reveal the essence and advantages of FM-DCSK. Based on that, comparative simulation and analysis between chaos spread-spectrum system based on FM-DCSK and its conventional equivalent is done and the superiority of a chaos communication over a conventional equivalent is found. Finally, several efficient error correcting codes are selected to verify the adaptability between FM-DCSK and channel coding. Those works are of practical signification for FM-DCSK to be applied in future wireless and mobile communication systems.