一种新型混沌扩频卫星隐蔽通信算法

Novel Algorithm of Satellite Covert Communication Based on Chaotic Spread Spectrum Modulation

针对Logistic及改进型混沌映射只存在唯一满映射点的缺陷,设计了一种新型混沌映射函数,拓宽了满映射参数的取值范围,进而提高了混沌序列遍历性,并基于相干混沌移位键控技术,构建了新型混沌扩频卫星隐蔽通信系统。分别对新型混沌序列的随机性、相关性和平衡性,以及隐蔽通信系统的误码率进行了仿真分析,结果表明:新型混沌映射比已有映射遍历性更好,平衡性更高。原业务信号与扩频调制信号的功率比值大于20dB时,原业务接收机接收误码率基本不受影响。扩频因子为80、信道信噪比大于6dB时,隐蔽接收机误码率小于10-3,能满足一定的隐蔽通信要求。

In view of the fact that traditional Logistic-Map as well as the modified Logistic-Map only have one surjective parametera,a new chaotic map function was designed,which broadens the range of surjective parameter so as to improve the ergodic property of the chaotic sequence.Based on the coherent chaos shift-keying modulation,a new satellite covert communication system with chaotic spread spectrum was installed.The randomness correlationbalance property of the referred chaotic sequence and the error rate of the covert communication system were analyzed.The simulation results show that the referred chaotic is better than the traditional Logistic chaotic in ergodic property and balance property.The bit error rate of original service receiver is not changed when the power ratio of original service signal to spread spectrum modulated signal is greater than 20 dB.The bit error rate of covert communication receiver is below 10-3 when the spread spectrum factor is 80 and the SNR（Signal to Noise Ratio）is greater than 6dB.The proposed system can meet the covert communication requirements.