Design And Simulation Of DSSS Based On Chaotic Sequence

Due to excellent ability of security and anti-jamming, spread spectrum communication has a great deal of applications in modern communication system. The modulation technology based on chaos has been studied in recent years. On the basis of analyzing spectrum spreaded communication, aim at the flaw in secrecy of DSSS, system design and performance simulation have been done in this thesis. The system is in a cascade way to promote its secrecy and different chaotic sequence will be used in different communication to implement that while spreading the spectrum of the information code the system will simultaneously complete the encryption to the information.The performance of the spread spectrum communication system is determined by the spread spectrum code used in the system. Traditional spread spectrum sequences have flaws in secrecy which cause the system unsecured. In view of this flaw, the chaotic spread spectrum sequence was selected in this thesis. Different chaotic spread spectrum sequences were used at a time in each communication so that the system can encrypt the information sequence as while as spreading the spectrum of the information. RSA was used to encrypt the initianal value of the chaotic spread spectrum sequence in order to enhance the securecy of the system.The system is divided into the chaos sequence the module, LDPC coding and decoding module, the RSA encryption and decryption module. These modules the design and the mathematical simulation completed, the whole system performance simulation was carried on. Several kinds of common chaos map was simulated to generate chaotic sequence. Then perfomance analysis of these sequences were done in this thesis. The simulation to the LDPC encoding and the decoding was carried on as well as the simulation to the RSA encryption and decryption. Finally simulation to the whole system was done, and results showed that the performance of the system is good.The work of this thesis showed the feasibility of the use of chaotic sequence in DSSS, and the system designed in this thesis is stronger than traditional DSSS in secrecy. Use of LDPC in the system further strengthens the system communication performance.