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PhD Final Oral Examination – Nadia Adem


Friday, September 16, 2016 9:00 AM - 11:00 AM

Jamming Attack Resiliency and Performance Analysis of Cognitive Radio Communication Networks
Cognitive radio technology emerges as a promising solution for overcoming shortage and inefficient use of spectrum resources. In cognitive radio networks, secondary users, which are users equipped with cognitive radios, can opportunistically access spectrum assigned to primary users, the spectrum license holders. Although it improves spectrum utilization efficiency, this opportunistic spectrum access incurs undesired delays that can degrade the quality of service (QoS) of delay-sensitive applications substantially. It is therefore important to understand, model, and characterize these delays, as well as their dependency on primary user behaviors. Moreover, the lack of access priority also leads to significant performance degradation when the network is under jamming attacks. It turns out that addressing jamming attacks while maintaining a desired QoS is very challenging. In this thesis, we characterize the properties of the random process that describes the availability of the opportunistic resources, and analytically model and analyze cognitive network average delays. Furthermore, we propose and study new techniques that mitigate jamming attacks in mobile cognitive radio networks. More specifically, this thesis consists of the following three complimentary frameworks:

  1. Stochastic Resource Availability Modeling and Delay Analysis: In this framework, we define and characterize the properties of the random process that describes the availability of the opportunistic network resources. We apply the mean residual service time concept to derive an analytical solution for the cognitive network queueing delay. We model the service mechanism, and determine the manner in which it depends on spectrum availability. We show that the delay becomes unbounded if spectrum dynamics are not carefully considered in network design.
  2. Pseudorandom Time-Hopping Anti-Jamming Technique: In this framework, we propose and evaluate jamming countermeasure approaches for mobile cognitive users. We propose two time-based techniques which, unlike other existing frequency-based techniques, do not assume accessibility to multiple channels and hence do not rely on switching to countermeasure jamming. In these two techniques, we allocate data over time based on cryptographic and estimation methods. We derive analytical expressions of the jamming, switching and error probabilities. Our findings show that our proposed technique outperforms other existing frequency-based techniques.
  3. Optimally Controlled Time-Hopping Anti-Jamming Technique: In this framework, we propose a jamming and environment aware resource allocation method for mobile cognitive users. We propose to mitigate jamming based on an optimal allocation of data over time. In addition, we optimally control network mobility to meet a desired QoS. Our findings show that our proposed technique achieves better QoS than those achieved by existing cryptographic methods while not compromising jamming resiliency.

Major Advisor: Bechir Hamdaoui
Committee: Attila Yavuz
Committee: Arun Natarajan
Committee: Rakesh Bobba
GCR: Maggie Niess


Kelley Engineering Center (campus map)
1007
Nicole Thompson
1 541 737 3617
Nicole.Thompson at oregonstate.edu
Sch Elect Engr/Comp Sci
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