Opportunistic spectrum access (OSA) is at the core of the cognitive radio technologies with the focus on improving spectrum utilization efficiency and reliability. Despite the benefits, existing OSA protocols suffer from their deterministic nature and cannot prevent an ill-intended jammer from disrupting legitimate communications. A cognitive jammer can always effectively jam the idle channels by exploiting public-available channel statistics and causes serious spectrum underutilization. This project addresses the challenge of establishing robust anti-jamming communication in cognitive radio networks (CRNs) through a multiple-line of defense approach. The research considers a variety of network environments and integrates defense technologies from different dimensions, including adaptive uncoordinated frequency hopping (AUFH), power control, and signal processing. The defense approach enables both reactive and proactive protections, from evading jammers to competing against jammers, and to expelling jamming signals, and thus ensures robust user communications in CRNs.

The research in this project has a potential to significantly advance the state-of-the-art and develop innovative and sophisticated defense strategies using the proposed multiple lines of defense approach. The proposed solutions will contribute towards eventually building robust and dependable CRNs that are critical to the future communication systems. The project will also contribute directly to the curriculum development, teaching, student supervising and future security engineer training. Major results of this project will be disseminated through presentations, publications, as well as online materials in the forms of tutorials and software packages.

The first research module is Jamming-resistant Opportunistic Spectrum Access in CRNs. In our most recent work, we formulate the anti-jamming multi-channel access problem as a non-stochastic multi-armed bandit (NS-MAB) problem. By leveraging probabilistically shared information between the sender and the receiver, our proposed protocol enables them to hop to the same set of channels with high probability while gaining resilience to jamming attacks without affecting PUs’ activities. In this work, we considered a SU network with a single sender-receiver pair, i.e., one hop and single sender-receiver setting. In this performance period, we further consider the following two problems.

Our second research module is Privacy-preserving Spectrum Auction in CRNs. In our most recent work, we investigate the problem of allocating idle channels to spectrum users with homogeneous demands in CRNs where available channels are arriving in a dynamic and random order. Taking spectrum reusability into consideration, we first propose THEMIS-I: a novel and efficient spectrum auction algorithm that achieves fair pricing for homogeneous channels, online spectrum auction under dynamic spectrum supply and a log approximation to the optimal social welfare. To enhance the robustness of the system, we further propose THEMIS-II: a collusion-resistant design that can resist any number of coalition groups of small size while still possessing all the above desirable properties. We analytically show that THEMIS can achieve either truthfulness without collusion or t-truthfulness tolerating a collusion group of size t with high probability. In this performance period, we further consider the following problems.

Our third research module is Physical-Layer Identification in Wireless Networks. The wireless physical-layer identification (WPLI) techniques utilize the unique features of the physical waveforms of wireless signals to identify and classify authorized devices. As the inherent physical-layer features are difficult to forge, WPLI is deemed as a promising technique for wireless security solutions. The results and findings can be used in legitimate spectrum user authentication in CRNs. In this research component, through both theoretical modeling and experiment validation, the reliability and the differentiability of the WPLI techniques are rigorously evaluated, especially under the constraints of the state-of-the-art wireless devices, real operation environments, as well as wireless protocols and regulations. The real-world requirements and constraints are characterized along each step in WPLI, including: 1) the signal processing at the transmitter (device to be identified); 2) the various physical-layer features that originate from circuits, antenna, and environments; 3) the signal propagation in various wireless channels; 4) the signal reception and processing at the receiver (the identifier); and 5) the fingerprint extraction and classification at the receiver.

Q. Wang, Q. Sun, K. Ren, and X. Jia, “Themis: Collusion-resistant and fair pricing spectrum auction under dynamic supply,” IEEE Transactions on Mobile Computing (TMC), 2017. [cite]

Y. Dou, H. Li, K. Zeng, J. Liu, Y. Yang, B. Gao, K. Ren, “Preserving Incumbent Users’ Privacy in Exclusion-Zone-Based Spectrum Access Systems,” in Procedings of IEEE 35th International Conference on Distributed Computing Systems (ICDCS), 2017. [cite]

C. Guan, A. Mohaisen, Z. Sun, L. Su, K. Ren, Y. Yang, “When Smart TV Meets CRN: Privacy-preserving Fine-grained Spectrum Access,” in Procedings of IEEE 35th International Conference on Distributed Computing Systems (ICDCS), 2017. [cite]

Y. Dou, K. Zeng, H. Li, Y. Yang, B. Gao, K. Ren, S. Li, “P2-SAS: Privacy-Preserving Centralized Dynamic Spectrum Access System,” IEEE Journal on Selected Areas in Communications, 2016. [cite]

Y. Dou, K. Zeng, Y. Yang, K. Ren, “Preserving incumbent users' privacy in exclusion-zone-based spectrum access systems: poster,” Proceedings of the 22nd Annual International Conference on Mobile Computing and Networking (MobiCom’16), 2016. [cite]

Q. Wang, K. Ren, P. Ning, and S. Hu, “Jamming-resistant multi-radio multi-channel opportunistic spectrum access in crns,” IEEE Transactions on Vehicular Technology (TVT), 2016. [cite]

W. Wang, Z. Sun, S. Piao, B. Zhu, and K. Ren, “Wireless physical-layer identification: Modeling and validation,” IEEE Trans. Information Forensics and Security, vol. 11, no. 9, pp. 2091–2106, 2016. [cite]

W. Wang, Z. Sun, K. Ren, and B. Zhu, “Increasing user capacity of wireless physical-layer identification in internet of things,” in Proc. of GlobeCom’16, 2016. [cite]

• Q. Wang, K. Ren, G. Li, C. Xia, X. Chen, Z. Wang, and Q. Zou, "Walls Have Ears! Opportunistically Communicating Secret Messages Over the Wiretap Channel: from Theory to Practice", in Proceedings of the 2015 ACM SIGSAC Conference on Computer Communications Security (CCS), 2015 [cite]

• Q. Wang, Q. Sun, K. Ren, X. Jia, and Z. Wang, "Themis: Collusion-resistant and fair pricing spectrum auction under dynamic supply," IEEE Transactions on Mobile Computing (TMC), 2015, under review.

• Q. Wang, K. Ren, and P. Ning, "Jamming-resistant multi-radio multi-channel opportunistic spectrum access in CRNs," IEEE Transactions on Vehicular Technology (TVT), 2015, under review.

2013-2014

• B. Zhang and Q. Zhan and J. Wang and K. Ren and C. Wang and D. Ma, "PriWhisper: Enabling Keyless Secure Acoustic Communication for Smartphones.", IEEE Internet of Things, 2014 [cite]

• Q. Yue, Z. Ling, X. Fu, B. Liu, K. Ren, and W. Zhao,"Fair Pricing in the Sky: Truthful Frequency Allocation with Dynamic Spectrum Supply", IEEE 22nd International Conference on Network Protocols (ICNP), 2014 [cite]

• M. Li, H. Zhu, Z. Gao, S. Chen, L. Yu, S. Hu, and K. Ren, "All Your Location Are Belong to Us: Breaking Mobile Social Networks for Automated User Location Tracking", Proceedings of the 15th ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), 2014 [cite]

• K. Ren and Q. Wang, "Opportunistic spectrum access: from stochastic channels to non-stochastic channels", IEEE Wireless Communications, 2013 [cite]