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Dynamic spectrum access (DSA) is an important design aspect for the cognitive radio networks. Most of the existing DSA schemes are to govern the unlicensed user (i.e., secondary user) traffic in a licensed spectrum without compromising the transmissions of the licensed users, in which all the unlicensed users are typically treated equally. In this paper, prioritized unlicensed user traffic is considered...
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...
In this paper, we propose an opportunistic scheduling scheme to serve bursty traffics in cognitive radios, where cooperative beamforming is exploited to access busy timeslots or spatial spectrum holes to forward messages without causing interference to primary users. Specifically, based on cooperative beamforming in the physical layer and automatic repeat request for error recovery in the link layer,...
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...
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