Physical-Layer Security with Multiuser Scheduling in Cognitive Radio Networks (1311.0404v1)

Abstract: In this paper, we consider a cognitive radio network that consists of one cognitive base station (CBS) and multiple cognitive users (CUs) in the presence of multiple eavesdroppers, where CUs transmit their data packets to CBS under a primary user's quality of service (QoS) constraint while the eavesdroppers attempt to intercept the cognitive transmissions from CUs to CBS. We investigate the physical-layer security against eavesdropping attacks in the cognitive radio network and propose the user scheduling scheme to achieve multiuser diversity for improving the security level of cognitive transmissions with a primary QoS constraint. Specifically, a cognitive user (CU) that satisfies the primary QoS requirement and maximizes the achievable secrecy rate of cognitive transmissions is scheduled to transmit its data packet. For the comparison purpose, we also examine the traditional multiuser scheduling and the artificial noise schemes. We analyze the achievable secrecy rate and intercept probability of the traditional and proposed multiuser scheduling schemes as well as the artificial noise scheme in Rayleigh fading environments. Numerical results show that given a primary QoS constraint, the proposed multiuser scheduling scheme generally outperforms the traditional multiuser scheduling and the artificial noise schemes in terms of the achievable secrecy rate and intercept probability. In addition, we derive the diversity order of the proposed multiuser scheduling scheme through an asymptotic intercept probability analysis and prove that the full diversity is obtained by using the proposed multiuser scheduling.

• The paper proposes a multiuser scheduling scheme designed to enhance the physical-layer secrecy rate in cognitive radio networks while satisfying primary user quality of service.
• Comparative analysis demonstrates that the proposed multiuser scheduling strategy generally provides superior secrecy rates compared to traditional scheduling and artificial noise methods, particularly at higher main-to-eavesdropper ratios.
• Asymptotic analysis reveals the proposed scheme achieves full diversity proportional to the number of cognitive users, highlighting its potential for improved security and resource efficiency in cognitive radio deployments.

Analysis of Physical-Layer Security in Cognitive Radio Networks with Multiuser Scheduling

In the paper titled "Physical-Layer Security with Multiuser Scheduling in Cognitive Radio Networks," the authors address the critical challenge of safeguarding cognitive radio networks against eavesdropping, leveraging multiuser scheduling techniques. The network architecture comprises a cognitive base station (CBS) and multiple cognitive users (CUs) coexisting with several eavesdroppers.

Key Contributions

1. Proposed Multiuser Scheduling Scheme: The central proposition of the paper is a multiuser scheduling (MUS) method aimed at enhancing the secrecy rate of cognitive transmissions. The method selects the cognitive user that can fulfill primary user's quality of service (QoS) requirements while maximizing secrecy.
2. Comparative Analysis: The paper undertakes a comprehensive analysis, juxtaposing the proposed MUS scheme with traditional scheduling techniques and artificial noise generation strategies in Rayleigh fading environments.
3. Diversity Order Improvement: An asymptotic analysis reveals that the proposed MUS scheme achieves full diversity, scaling with the number of CUs, thereby outperforming traditional multiuser strategies under specific conditions.

Numerical Insights

Through simulation, the authors demonstrate that, subject to a primary QoS constraint, the MUS strategy generally provides superior secrecy rates compared to other methods. This advantage becomes more pronounced as the main-to-eavesdropper ratio (MER) increases, underscoring MUS's efficacy in scenarios where the wiretap links are weak relative to the main link.

1. Secrecy Rate Trends: In low MER regimes, artificial noise outperforms both scheduling methods due to its capability to obscure eavesdroppers effectively. However, as MER escalates, the efficiency of this noise diminishes, and the MUS scheme gains the upper hand, showcasing its robustness against variations in channel conditions.
2. Impact of User and Eavesdropper Count: While increases in the number of CUs lead to higher achievable secrecy rates for the MUS scheme, adding more eavesdroppers has a less detrimental impact on artificial noise due to its inherent interference generation capability.

Theoretical and Practical Implications

• Security Enhancement: The research reinforces the potential of exploiting multiuser diversity in boosting physical-layer security, a critical consideration in the design of secure cognitive radio systems.
• Resource Efficiency: By optimizing user scheduling rather than relying on resource-intensive strategies such as artificial noise, MUS offers a resource-conserving approach that aligns with the imperative to maintain QoS for primary users.
• Future Applications: This work lays foundational insights for developing more adaptive, fair, and efficient scheduling algorithms that incorporate user fairness and dynamic environmental considerations, enhancing the security landscape of future cognitive radio deployments.

Conclusion

The detailed analysis presented in this paper highlights multiuser scheduling as a viable strategy for mitigating eavesdropping threats within cognitive radio networks. By demonstrating its superior performance in various channel conditions, the authors provide a compelling case for integrating MUS into the design and deployment strategies of wireless communication systems. Future explorations could further refine these results, incorporating additional real-world constraints and user fairness considerations, poised to broaden the applicability and effectiveness of cognitive radio solutions.