Maximizing Achievable Covert Rate in XL-RIS Empowered Near-Field Communications

Keskeiset käsitteet

This paper proposes an optimization framework to maximize the achievable covert rate in an XL-RIS empowered near-field communication system, by jointly optimizing the hybrid analog-digital beamforming at the transmitter and the reflection coefficient matrix at the XL-RIS.

Tiivistelmä

The paper studies an XL-RIS empowered covert communication system in the near-field region. Alice covertly transmits messages to Bob with the assistance of the XL-RIS, while evading detection by Willie.
Key highlights:

The near-field communications can achieve a higher covert rate than the far-field covert communications, and still realize covert transmission even if Willie is located at the same direction as Bob and closer to the XL-RIS.
An alternating optimization algorithm is proposed to solve the joint beamforming design problem.
For the hybrid beamformer design, a semi-closed-form solution for the fully digital beamformer is first obtained by a weighted minimum mean-square error based algorithm, then the baseband digital and analog beamformers at Alice are designed by approximating the fully digital beamformer via manifold optimization.
For the XL-RIS's reflection coefficient matrix design, a low-complexity alternating direction method of multipliers based algorithm is proposed to address the challenge of large-scale variables and unit-modulus constraints.
The proposed algorithm leads to a beam diffraction pattern that can bypass Willie and achieve high-rate covert transmission to Bob.

Tilastot

The received power at Willie is given by ∥FΘGWRFWBB∥2F.
The maximum allowed leakage power at Willie is given by pleak = min{MWbσ2W(ρ-1)/ρ, (e2κln(ρ)-1)/(MWbσ2W/ρ)}.

Lainaukset

"The near-field communications can achieve a higher covert rate than the far-field covert communications, and still realize covert transmission even if Willie is located at the same direction as Bob and closer to the XL-RIS."
"The proposed algorithm leads to a beam diffraction pattern that can bypass Willie and achieve high-rate covert transmission to Bob."

Tärkeimmät oivallukset

RIS Empowered Near-Field Covert Communications

by Jun Liu, Gan... klo arxiv.org 09-10-2024

https://arxiv.org/pdf/2401.13564.pdf

Syvällisempiä Kysymyksiä

How can the proposed algorithm be extended to scenarios with imperfect or partial Willie CSI at Alice?

The proposed algorithm can be adapted to scenarios with imperfect or partial Channel State Information (CSI) of Willie at Alice by employing robust optimization techniques. One approach is to utilize statistical methods that account for uncertainty in the channel estimates. For instance, the S-procedure and Bernstein-type inequalities can be applied to derive bounds on the performance metrics, allowing Alice to optimize her transmission strategy while considering the worst-case scenarios of Willie’s detection capabilities.
Additionally, the algorithm can incorporate a game-theoretic framework where Alice anticipates Willie’s strategies based on the available partial CSI. By formulating the optimization problem as a minimax problem, Alice can optimize her beamforming strategy to minimize the maximum possible detection probability by Willie. This approach ensures that even with limited information about Willie’s channel, Alice can maintain a desired level of covert communication performance.

What are the potential applications of the XL-RIS empowered near-field covert communications beyond wireless communications?

The XL-RIS empowered near-field covert communications have potential applications beyond traditional wireless communications, including:

Military Communications: In military operations, covert communication is crucial for secure information exchange among units without revealing their positions to adversaries. The use of XL-RIS can enhance stealth capabilities by directing signals away from enemy detection systems.

Smart Cities: In smart city environments, where numerous devices communicate wirelessly, XL-RIS can facilitate covert data transmission between sensors and control centers, ensuring privacy and security against unauthorized access.

Healthcare: In medical settings, covert communication can be vital for transmitting sensitive patient data between devices without alerting unauthorized personnel. XL-RIS can help maintain patient confidentiality while ensuring reliable data transfer.

Financial Transactions: Secure and covert communication is essential in financial services to protect sensitive transaction data. XL-RIS can enhance the security of wireless transactions, reducing the risk of interception.

Autonomous Vehicles: In vehicular networks, covert communication can be used for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications, ensuring that critical information is exchanged without being detected by potential attackers.

How can the proposed techniques be adapted to enhance the security and privacy of other wireless systems, such as Internet of Things or vehicular networks?

The proposed techniques from the XL-RIS empowered near-field covert communications can be adapted to enhance the security and privacy of other wireless systems, such as the Internet of Things (IoT) and vehicular networks, through the following methods:

Adaptive Beamforming: By implementing adaptive beamforming techniques, devices in IoT networks can dynamically adjust their transmission patterns to minimize the risk of detection by unauthorized entities. This can be particularly useful in environments with high interference or eavesdropping risks.

Covert Channels: The concept of covert channels can be integrated into IoT systems, allowing devices to communicate sensitive information without raising suspicion. By utilizing the XL-RIS to manipulate signal propagation, devices can create hidden communication paths that are less likely to be monitored.

Secure Data Aggregation: In vehicular networks, secure data aggregation techniques can be employed where vehicles use XL-RIS to transmit aggregated data to central servers covertly. This reduces the amount of sensitive information exposed during transmission, enhancing privacy.

Multi-layer Security Protocols: The algorithms can be incorporated into multi-layer security protocols that combine physical layer security with higher-layer encryption methods. This dual approach ensures that even if the physical layer is compromised, the data remains secure.

Anomaly Detection: By leveraging the detection performance analysis techniques used in covert communications, IoT systems can implement anomaly detection mechanisms to identify unauthorized access attempts or unusual communication patterns, thereby enhancing overall security.

By adapting these techniques, the security and privacy of wireless systems can be significantly improved, making them more resilient against various threats and vulnerabilities.