Covert or low probability of detection communication is crucial to protect user privacy and provide a strong security. We analyze the joint impact of imperfect knowledge of the channel gain (channel uncertainty) and noise power (noise uncertainty) on the average probability of detection error at the eavesdropper and the covert throughput in Rayleigh fading channel. We characterize the covert throughput gain provided by the channel uncertainty as well as the covert throughput loss caused by the channel fading as a function of the noise uncertainty. Our result shows that the channel fading is essential to hiding the signal transmission, particularly when the noise uncertainty is below a threshold and/or the receive SNR is above a threshold. The impact of the channel uncertainty on the average probability of detection error and covert throughput is more significant when the noise uncertainty is larger.Covert or low probability of detection communication is crucial to protect user privacy and provide a strong security. We analyze the joint impact of imperfect knowledge of the channel gain (channel uncertainty) and noise power (noise uncertainty) on the average probability of detection error at the eavesdropper and the covert throughput in Rayleigh fading channel. We characterize the covert throughput gain provided by the channel uncertainty as well as the covert throughput loss caused by the channel fading as a function of the noise uncertainty. Our result shows that the channel fading is essential to hiding the signal transmission, particularly when the noise uncertainty is below a threshold and/or the receive SNR is above a threshold. The impact of the channel uncertainty on the average probability of detection error and covert throughput is more significant when the noise uncertainty is larger.

International Conference on CommunicationsMay 1, 201978 citations

Secret Communication Under Channel Uncertainty

Yingbin Liang, H. Vincent Poor, Shlomo Shitz Shamai

Springer eBooksJan 1, 20091 citation

Stealthy Communication over Noisy Channels: Channel Capacity and The Role of Randomization

Abdalla Ibrahim, Johannes Rosenberger, Boulat A. Bash +2 more

IEEE International Symposium on Information Theory (ISIT)Jun 1, 20260 citations

Covert Communications Under Environmental Uncertainty on a Continuous-Time Channel

Amna Gillani, Tamara V. Sobers, Don Towsley +1 more

Covert communication is achieved when a transmitter Al-ice can successfully transmit a message to a receiver Bob without being detected by an attentive and capable adversary Willie. Early results demonstrated the difficulty of the covert communications problem: with AWGN discrete-time channels between all parties, only $O(\sqrt{n})$ bits can be sent in $n$ channel uses. But it was soon recognized that uncertainty about the environment at Willie, for example, uncertainty in his own noise statistics, could allow for a positive rate: $O(n)$ bits can be sent covertly in $n$ channel uses. However, most covert communication results, including this promising positive rate result, have been obtained for a discrete-time communications channel. Here, we demonstrate that the assumption of a discrete-time channel is problematic when trying to exploit Willie's noise uncertainty. In particular, we demonstrate that if Alice transmits $\omega(\sqrt{T})$ bits in a length $T$ interval to Bob on a continuous-time channel, then there exists a detector at Willie that can detect her transmission, as the probability of false alarm and missed detection $P_{MD}+P_{FA}\rightarrow 0$ as $T\rightarrow\infty$ . In other words, the communication is not covert, unlike the case of a discrete-time channel.Covert communication is achieved when a transmitter Al-ice can successfully transmit a message to a receiver Bob without being detected by an attentive and capable adversary Willie. Early results demonstrated the difficulty of the covert communications problem: with AWGN discrete-time channels between all parties, only$O(\sqrt{n})$bits can be sent in$n$channel uses. But it was soon recognized that uncertainty about the environment at Willie, for example, uncertainty in his own noise statistics, could allow for a positive rate:$O(n)$bits can be sent covertly in$n$channel uses. However, most covert communication results, including this promising positive rate result, have been obtained for a discrete-time communications channel. Here, we demonstrate that the assumption of a discrete-time channel is problematic when trying to exploit Willie's noise uncertainty. In particular, we demonstrate that if Alice transmits$\omega(\sqrt{T})$bits in a length$T$interval to Bob on a continuous-time channel, then there exists a detector at Willie that can detect her transmission, as the probability of false alarm and missed detection$P_{MD}+P_{FA}\rightarrow 0$as$T\rightarrow\infty$. In other words, the communication is not covert, unlike the case of a discrete-time channel.

Asilomar Conference on Signals, Systems and Computers (ACSSC)Oct 29, 20231 citation

Research on improving the security and reliability of covert communication systems

Yaocong Xie, Haoming Wang, Enyu Li +2 more

Annals of TelecommunicationsJul 30, 20260 citations

Covert Communication Based on Noise Uncertainty Against Multi-Antenna Detection: Analyses of Limit Covert and Reliable Rate

Weiyu Chen, Haiyang Ding, Shilian Wang +3 more

Uncertainty about noise variance is unavoidable. Many existing works exploited the noise uncertainty for covert communication and meanwhile assumed that the adversary third party Willie adopts a radiometer detector, in which case a positive covert and reliable rate O(N) bits/N channel uses is achievable. Nonetheless, the radiometer is not optimal in general. The limit covert and reliable rate based on noise uncertainty against the optimal detector remains unknown. To shed light on this problem, this letter proves that when Willie suffers from noise uncertainty but has two or more antennas for detection, the limit covert and reliable rate over additive white Gaussian noise channels is O(N) bits/N channel uses. This rate is the same as the limit rate without the noise uncertainty, which means that the covert performance gain stemming from the noise uncertainty is indeed fragile. The key of the proof is the proposed correlation detector for Willie, which is easy to deploy and does not require any knowledge about channel coefficients or transmitter’s codebook.Uncertainty about noise variance is unavoidable. Many existing works exploited the noise uncertainty for covert communication and meanwhile assumed that the adversary third party Willie adopts a radiometer detector, in which case a positive covert and reliable rate O(N) bits/N channel uses is achievable. Nonetheless, the radiometer is not optimal in general. The limit covert and reliable rate based on noise uncertainty against the optimal detector remains unknown. To shed light on this problem, this letter proves that when Willie suffers from noise uncertainty but has two or more antennas for detection, the limit covert and reliable rate over additive white Gaussian noise channels is O(N) bits/N channel uses. This rate is the same as the limit rate without the noise uncertainty, which means that the covert performance gain stemming from the noise uncertainty is indeed fragile. The key of the proof is the proposed correlation detector for Willie, which is easy to deploy and does not require any knowledge about channel coefficients or transmitter’s codebook.

IEEE Wireless Communications LettersOct 11, 20235 citations

O(\sqrt{n})

bits can be sent in

n

channel uses. But it was soon recognized that uncertainty about the environment at Willie, for example, uncertainty in his own noise statistics, could allow for a positive rate:

O(n)

bits can be sent covertly in

n

channel uses. However, most covert communication results, including this promising positive rate result, have been obtained for a discrete-time communications channel. Here, we demonstrate that the assumption of a discrete-time channel is problematic when trying to exploit Willie's noise uncertainty. In particular, we demonstrate that if Alice transmits

\omega(\sqrt{T})

bits in a length

T

interval to Bob on a continuous-time channel, then there exists a detector at Willie that can detect her transmission, as the probability of false alarm and missed detection

P_{MD}+P_{FA}\rightarrow 0

T\rightarrow\infty

. In other words, the communication is not covert, unlike the case of a discrete-time channel.