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Continuous authentication is an important prevention-based approach to protect high security mobile ad-hoc networks (MANETs). On the other hand, intrusion detection systems (IDSs) are also important in MANETs to effectively identify malicious activities. Considering these two approaches jointly is effective in optimal security design taking into account system security requirements and resource constraints...
Opportunistic spectrum access (OSA) is a key technique for the secondary user (SU) in a Cognitive Radio network to transmit over the "spectrum holes" unoccupied by the primary user (PU). Most existing work on the design of OSA has assumed a non-reactive (NR) PU model, i.e., the PU transmission on-off status is independent of the SU access policy, which may not be practical. In this paper,...
We consider an opportunistic channel access problem over multiple primary bands. We exploit primary ACK/NAK packets overhearing to overlay secondary communications on top of permanently busy primary channels. Through the theory of multi-armed restless bandit processes (MARB), we prove optimality of the myopic policy with a simple structure that does not require channel state-transition probabilities...
A critical challenge in Cognitive Radio Networks (CRN) is to make decision in real-time on accessing and releasing available channels that maximize the spectrum utilization and the overall system throughput. In this work, we make investigations on optimal action point to explore and exploit the frequency-temporal diversity in addition to spectrum availability. By modeling the Rayleigh fading channel...
Analytical formulations of the throughput of cognitive multi-channel MACs with perfect and imperfect sensing are presented. Both imperfect concurrent sensing and imperfect sequential sensing schemes are considered. A discrete time Markov chain is used to model the number of communicating node pairs in the MAC protocols. The throughput of the MAC protocol with perfect sensing is expressed as a function...
Many spectrum sensing and access schemes have been proposed in recent years for opportunistic spectrum access (OSA). Most of them model the spectrum sensing and access problem as a partially observed Markov decision process (POMDP), where the channel statistics are assumed to be known to the secondary users (SU). However, few of them have considered the attackers who can launch effective jamming attacks...
In cognitive radio networks, it is important to effectively use the under-utilized spectrum resources without affecting the primary users. In an underlay system, cognitive users are allowed to share the channel simultaneously with primary users with the restriction on interference level but not in an overlay system. In this paper, we consider a system where cognitive users can switch between overlay...
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