Improving Physical Layer Secrecy Using Full-Duplex Jamming Receivers (1308.0094v1)

Abstract: This paper studies secrecy rate optimization in a wireless network with a single-antenna source, a multi-antenna destination and a multi-antenna eavesdropper. This is an unfavorable scenario for secrecy performance as the system is interference-limited. In the literature, assuming that the receiver operates in half duplex (HD) mode, the aforementioned problem has been addressed via use of cooperating nodes who act as jammers to confound the eavesdropper. This paper investigates an alternative solution, which assumes the availability of a full duplex (FD) receiver. In particular, while receiving data, the receiver transmits jamming noise to degrade the eavesdropper channel. The proposed self-protection scheme eliminates the need for external helpers and provides system robustness. For the case in which global channel state information is available, we aim to design the optimal jamming covariance matrix that maximizes the secrecy rate and mitigates loop interference associated with the FD operation. We consider both fixed and optimal linear receiver design at the destination, and show that the optimal jamming covariance matrix is rank-1, and can be found via an efficient 1-D search. For the case in which only statistical information on the eavesdropper channel is available, the optimal power allocation is studied in terms of ergodic and outage secrecy rates. Simulation results verify the analysis and demonstrate substantial performance gain over conventional HD operation at the destination.

• The paper develops a secrecy rate optimization framework that leverages full-duplex jamming receivers to mitigate interference and enhance physical layer security.
• It demonstrates that, with global CSI, the optimal jamming covariance matrix is rank-1 and can be computed efficiently via a one-dimensional search.
• For scenarios with limited eavesdropper information, the study proposes optimal power allocation to achieve superior outage and ergodic secrecy rates compared to half-duplex systems.

An Analysis of "Improving Physical Layer Secrecy Using Full-Duplex Jamming Receivers"

This paper delineates an innovative approach to bolster physical layer security in wireless networks through the deployment of full-duplex (FD) jamming receivers. The problem addressed involves enhancing the secrecy rate in the presence of an eavesdropper within a system comprising a single-antenna source, a multi-antenna destination, and a multi-antenna eavesdropper. This scenario poses a significant challenge due to the interference-limited nature of the system.

Core Contributions

The core contributions of the research are articulated through the development of a secrecy rate optimization framework which navigates the interference issues using FD receivers adept in simultaneously transmitting jamming noise while receiving data. The authors highlight several technical achievements, including:

• Optimal Jamming Covariance Matrix: The research identifies that when global Channel State Information (CSI) is available, the optimal jamming covariance matrix is rank-1 and can be efficiently determined through a 1-D search.
• Impact of Limited Information: For cases where only statistical information about the eavesdropper's channel is available, the paper explores optimal power allocation strategies, considering both ergodic and outage secrecy rates, to demonstrate substantial performance gains over conventional half-duplex (HD) operations.
• Analytical Insights on Gain and Performance: The work provides analytical insights indicating that the system's interference-limited nature can be overcome, and the secrecy rate does not suffer from saturation at high Signal-to-Noise Ratios (SNR) as in the HD case.

Critical Findings and Numerical Results

The paper also emphasizes certain numerical results which substantiate the theoretically proposed solutions:

1. Secrecy Rate Sustainability: The introduction of FD operations at the destination results in secrecy rates that can continuously improve with increasing SNR, thus avoiding the saturation typically observed in HD systems.
2. Impact of Receiver Design: The research systematically establishes that the receiver design plays a crucial role in dealing both with the desired signal and residual self-interference, particularly when multiple antennas are available for transmission and reception.
3. Outage and Ergodic Secrecy Rates: When only the Channel Distribution Information (CDI) of the eavesdropper is known, the proposed FD system can successfully enhance both ergodic and outage secrecy rates when contrasted against HD systems.

Implications and Future Directions

The implications of this paper are profound, reflecting both theoretical and practical advancements in the field of secure wireless communication. This FD approach mitigates the dependency on external jamming nodes, thereby addressing the concerns related to helper mobility, synchronization, and trustworthiness. Furthermore, the research enriches the understanding of PHY layer security mechanisms in interference-prone environments.

Looking forward, the integration of advanced interference mitigation techniques, such as the simultaneous employment of zero-forcing for self-interference reduction, can further enhance system efficiency. Additionally, exploring adaptive schemes that reconcile varying levels of interference with dynamic system configurations remains a fertile area for future investigations. The work also opens avenues to broaden adversary models to include FD capabilities, thereby enriching the game-theoretical frameworks applied within security-oriented network designs.

In conclusion, this paper provides a comprehensive quantitative and qualitative exploration of employing FD jamming receivers for PHYSICAL layer security, demonstrating its viability as an apt counter-measure against passive eavesdropping threats in complex wireless networks.