Design Of Chaos Frequency Hopping Sequences With Given Minimum Gap And The Application In Communication System

In recent years, the use of chaotic maps to generate frequency hopping sequence with chaoticproperties, which is used in frequency hopping communications, has been research focus of spreadspectrum communications and secure communications. With the development of wirelesscommunication technology, the third even the fourth generation mobile communication technologyhave developed intensively and used widely. As a major physical layer technology for4G era,OFDM is what we should further explore and improve.In this paper, an improved map based on Logistic map is proposed. The proposed map is anovel chaos map which made by two levels of Logistic map. By designing fractal coefficient ofLogistic map, the proposed map can effectively overcome the problems of attractor in Logistic map.Analysis and simulation carried out from Lyapunov indicator show that the range of fractalcoefficient of the improved map is wider than the existing Logistic map. Besides, analysis andsimulation from the perspective of power spectrum and phase space show that the improved maphas good chaos characteristic, which result in excellent confidential performance in chaos hoppingcommunications.Second, based on the improved map mentioned above, two new methods of frequency hoppinginterval extension are then proposed in this paper, one method is adding fixed prefix, and the othermethod is adding random prefix. Both have their own advantages and can effectively extend theinterval of the frequency hopping sequence, and are more effective than traditional method. Theproposed method improves anti-multipath interference performance of the chaotic frequencyhopping communications. Compared to traditional methods, this method has the advantages of highefficiency of sequence generation.Finally, the paper proposes the adoption of chaotic FH sequences in FH-OFDM system,modulate FH-OFDM system with chaotic frequency hopping sequence with given minimum gapconstructed in this paper, and make a comparison of different mapping’s sequences. This paper alsopreliminarily analyzes the simulation results and makes some worthy attempts to the FH-OFDMcommunication system in secure communication.