Challenges in Covert Wireless Communications with Active Warden on AWGN channels
This addresses security vulnerabilities in low-probability-of-detection communications for wireless systems, highlighting a critical limitation in existing models.
The paper tackles the problem of covert wireless communications by analyzing the impact of an active warden on AWGN channels, finding that the warden can easily detect transmissions via a trend test, invalidating the square root law and shortening detection time.
Covert wireless communication or low probability of detection (LPD) communication that employs the noise or jamming signals as the cover to hide user's information can prevent a warden Willie from discovering user's transmission attempts. Previous work on this problem has typically assumed that the warden is static and has only one antenna, often neglecting an active warden who can dynamically adjust his/her location to make better statistic tests. In this paper, we analyze the effect of an active warden in covert wireless communications on AWGN channels and find that, having gathered samples at different places, the warden can easily detect Alice's transmission behavior via a trend test, and the square root law is invalid in this scenario. Furthermore, a more powerful warden with multiple antennas is harder to be deceived, and Willie's detection time can be greatly shortened.