Achieving Covert Wireless Communications Using a Full-Duplex Receiver (1810.06741v1)

Abstract: Covert communications hide the transmission of a message from a watchful adversary while ensuring a certain decoding performance at the receiver. In this work, a wireless communication system under fading channels is considered where covertness is achieved by using a full-duplex (FD) receiver. More precisely, the receiver of covert information generates artificial noise with a varying power causing uncertainty at the adversary, Willie, regarding the statistics of the received signals. Given that Willie's optimal detector is a threshold test on the received power, we derive a closed-form expression for the optimal detection performance of Willie averaged over the fading channel realizations. Furthermore, we provide guidelines for the optimal choice of artificial noise power range, and the optimal transmission probability of covert information to maximize the detection errors at Willie. Our analysis shows that the transmission of artificial noise, although causes self-interference, provides the opportunity of achieving covertness but its transmit power levels need to be managed carefully. We also demonstrate that the prior transmission probability of 0.5 is not always the best choice for achieving the maximum possible covertness, when the covert transmission probability and artificial noise power can be jointly optimized.

• The paper proposes using a full-duplex receiver to generate artificial noise, enhancing covert wireless communications by obscuring transmissions from an adversary.
• Key findings include analyzing the trade-off between artificial noise power, self-interference, and detection error probability at the adversary, showing how managing these is crucial for covertness.
• The research implies that robust self-interference mitigation is essential for applying full-duplex systems in covert communications and suggests flexible transmission probabilities for maximum security.

Achieving Covert Wireless Communications Using a Full-Duplex Receiver

The paper "Achieving Covert Wireless Communications Using a Full-Duplex Receiver" by Khurram Shahzad et al. provides a sophisticated analysis of covert communication strategies in wireless networks, focusing on utilizing a full-duplex receiver to enhance communication security. This research is critical as it addresses the ever-increasing need for secure transmission in environments prone to eavesdropping.

Overview

The paper explores covert communications in wireless systems characterized by fading channels, emphasizing the role of a full-duplex (FD) receiver in generating artificial noise (AN) to obscure transmissions from a potential adversary, termed Willie. The pivotal contribution of the paper lies in the analytical derivation of optimal detection performance at Willie, the adversary, whose detection strategy is hindered by the randomness introduced in the AN's transmit power. Importantly, the researchers address the balance between self-interference and the necessity for AN in achieving effective covert communications.

Numerical Results and Analytical Insights

Key findings indicate that while AN significantly enhances the covertness of communication, managing its power levels is crucial due to the self-interference at the FD receiver. This self-interference impacts the signal-to-noise ratio (SNR) at the intended receiver. The paper presents a closed-form expression for detection errors at Willie and explores the optimization of AN power range alongside the transmission probability to maximize detection errors.

The authors justify the assumption of a radiometer at Willie for its simplicity and efficacy in practical applications. They establish that with fading channel conditions, a square root limit, which typically diminishes achievable rates in covert communications under perfect statistical conditions, can be surpassed. The analytical framework identifies scenarios where a positive covert communication rate is achievable by leveraging Willie's ignorance regarding the statistical characteristics of the AN power.

Implications and Future Directions

The findings from this research have both theoretical and practical implications. They underline that robust self-interference mitigation techniques can increase the feasibility of applying FD systems for covert communications in dynamic environments. Furthermore, the paper challenges the conventional wisdom on transmission probability, suggesting that a priori probabilities of transmission should be more flexible to ensure maximum covertness.

The implications extend towards the design of future communication systems where covert communications become increasingly crucial, such as in settings demanding secure data exchange without detection – military operations being a prime example. The methodology can further inspire designs involving cooperation between multiple nodes generating AN and how these can be orchestrated to optimize secure communication strategies.

Conclusion

The research by Shahzad et al. furnishes the academic community with profound insights into covert wireless communication strategies utilizing FD receivers. By meticulously analyzing the interdependencies between self-interference, transmission probability, AN power, and detection likelihood, this work not only opens avenues for enhancing communication security but also sets a benchmark for further explorations in physical layer security. Future developments in artificial noise strategies and self-interference management will indeed benefit from the comprehensive analytical groundwork laid by this paper.

This paper is a valuable addition to the literature on wireless security, providing a substantial foundation for researchers aiming to explore innovative solutions for secure covert communication in complex network scenarios.