基于乘性加扰的卫星信号遮蔽传输方案

Covert satellite signal transmission scheme based on multiplicative interference

针对卫星发送功率受限的情况,提出了一种卫星信号遮蔽传输的新方案。在卫星上,通过将待传输的业务信号与特别设计的非恒包络遮蔽信号相乘,隐藏了原业务信号的时频域特征。在授权地面站,利用遮蔽信号副本进行互相关时延估计并解遮蔽,从而恢复原业务信号。该方案具有不增加卫星的传输功耗、星上遮蔽运算复杂度低、传输安全性强等特点。此外,通过处理损耗、互信息等定量评价指标,分析了遮蔽方案的遮蔽性能。仿真实验表明,该遮蔽方案可以实现良好的时频域遮蔽效果。遮蔽后信号与原业务信号间的互信息结果表明:遮蔽后信号与原业务信号间相关性很弱,已基本掩盖原业务信号通信特征。在遮蔽信号与原业务信号带宽之比不小于0.3、信噪比不小于–4 dB的条件下,授权地面站解遮蔽的处理损耗可以控制在1 dB以内,具有良好的实用价值。

In view of the limited transmission power of satellite,a new scheme of covert satellite signal transmission is proposed.On the satellite,the time-frequency domain characteristics of the original service signal are hidden by multiplying the service signal to be transmitted with the specially designed non-constant envelope masking signal.At the authorized ground station,the masking signal replica is used for cross-correlation time delay estimation and de-masking,so as to restore the original service signal.This scheme has the advantages of no increase in transmission power consumption,low complexity of on-board masking operation and strong transmission security.In addition,the covert performance of the scheme is analyzed through quantitative evaluation indexes such as processing loss and mutual information.Simulation results show that the masking scheme can achieve good masking effect in time-frequency domain.The mutual information between the masked signal and the original service signal shows that the correlation between the masked signal and the original service signal is very weak,and the communication characteristic of the original service signal has been basically covered.Under the condition that the ratio of the masking signal to the original service signal bandwidth is not less than 0.3,and the signal-to-noise ratio is not less than–4 dB,the processing loss of authorized ground station de-masking processing can be controlled within 1 dB,which has good practical value.