Physical Layer Security in Millimeter Wave Cellular Networks (1604.07506v1)

Abstract: Recent researches show that millimeter wave (mmWave) communications can offer orders of magnitude increases in the cellular capacity. However, the secrecy performance of a mmWave cellular network has not been investigated so far. Leveraging the new path-loss and blockage models for mmWave channels, which are significantly different from the conventional microwave channel, this paper comprehensively studies the network-wide physical layer security performance of the downlink transmission in a mmWave cellular network under a stochastic geometry framework. We first study the secure connectivity probability and the average number of perfect communication links per unit area in a noise-limited mmWave network for both non-colluding and colluding eavesdroppers scenarios, respectively. Then, we evaluate the effect of the artificial noise (AN) on the secrecy performance, and derive the analysis result of average number of perfect communication links per unit area in an interference-limited mmWave network. Numerical results are demonstrated to show the network-wide secrecy performance, and provide interesting insights into how the secrecy performance is influenced by various network parameters: antenna array pattern, base station (BS) intensity, and AN power allocation, etc.

• The paper analyzes physical layer security in mmWave cellular networks using stochastic geometry, accounting for unique channel characteristics like path-loss and blockage.
• The research shows that high-gain directional antennas significantly enhance security performance in noise-limited scenarios.
• Deploying Artificial Noise (AN) and optimizing its power allocation can significantly improve security performance in interference-limited environments.

Overview of Physical Layer Security in Millimeter Wave Cellular Networks

The paper "Physical Layer Security in Millimeter Wave Cellular Networks" by Chao Wang and Hui-Ming Wang presents a comprehensive analysis of security performance in millimeter wave (mmWave) cellular networks. The research leverages stochastic geometry to investigate network-wide physical layer security, particularly under varying scenarios of eavesdropper collusion and the impact of artificial noise (AN).

Millimeter wave technology, characterized by high frequency bands, is promising for enhancing cellular network capacity. However, the security aspects, particularly through physical layer techniques, remain under-explored. This paper adds to the field by modeling the mmWave channel differently from the conventional microwave channel, accounting for path-loss and blockage. These differences form the basis for evaluating the secure connectivity probability and the average number of perfect communication links per unit area in a mmWave network.

Key Contributions

1. Noise-Limited Network Security: The authors consider a noise-limited mmWave scenario, often a reality in urban environments due to the directional nature of mmWave signals and inherent blockages. They evaluate secure connectivity probability and deduce that high-gain narrow beam antennas significantly enhance security performance.
2. Artificial Noise-Assisted Security: With network interference considered, AN is deployed to improve security against eavesdropping in interference-limited environments. This section examines how AN impacts overall interference and security dynamically, suggesting optimal power allocation strategies based on antenna patterns and eavesdropper density.

Methodological Approach

The research applies stochastic geometry, modeling BSs and eavesdroppers as Poisson point processes. This facilitates an analytical evaluation of network-wide security metrics like secure connectivity probability and the average number of perfect communication links.

For noise-limited environments, two scenarios are evaluated: (i) non-colluding eavesdroppers, where they operate independently, and (ii) colluding eavesdroppers with shared information. The influence of the antenna array pattern, AN power allocation, and other network parameters, such as base station intensity, are assessed numerically.

Numerical Results and Insights

The numerical results reveal that mmWave networks can significantly outperform traditional microwave systems in terms of secrecy. This is attributed largely to their robustness to eavesdropper density and their use of highly directional beamforming, which decreases information leakage. The paper proves that optimal deployment of AN and directional antennas can maintain strong security performance even with increasing eavesdropper intensity.

Implications and Future Directions

Practically, this research underscores the importance of antenna design and strategic AN deployment in mmWave systems to maintain robust security. Theoretically, it sets a novel ground for leveraging stochastic geometry and directional transmissions in evaluating physical layer security.

Looking ahead, further development could include exploring multiple antenna receivers and evaluating how advanced beamforming strategies could further mitigate complex eavesdropper strategies. As mmWave technology moves closer to mainstream adoption in 5G and beyond, these insights could inform more secure and efficient cellular system designs.

In summation, the work of Wang and Hui-Ming Wang propels understanding of physical layer security in mmWave networks, suggesting that the integration of high-gain directional antennas and optimal AN allocation can achieve substantial security gains. This research will be instrumental as mmWave communications continue to evolve and expand.