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Sensing/monitoring of spectrum-availability has been identified as a key requirement for dynamic spectrum allocation in cognitive radio networks (CRNs). An important issue associated with MAC-layer sensing in CRNs is how often to sense the availability of licensed channels and in which order to sense those channels. To resolve this issue, we address (1) how(More)
In a cognitive radio network (CRN), in-band spectrum sensing is essential for the protection of legacy spectrum users, with which the presence of primary users (PUs) can be detected promptly, allowing secondary users (SUs) to vacate the channels immediately. For in-band sensing, it is important to meet the detectability requirements, such as the maximum(More)
Static spectrum allocation prohibits radio devices from using spectral bands designated for others. As a result, some bands are under-utilized while other bands are over-populated with radio devices. To remedy this problem, the concept of spectrum agility has been considered so as to enable devices to opportunistically utilize others’ spectral bands. In(More)
This article provides a comprehensive survey of cognitive radio technology, focusing on its application to dynamic spectrum access, especially from the perspective of realizing consumer-oriented CR networks. We first overview the state of the art in CR technology and identify its key functions across the protocol stack, such as spectrum sensing, resource(More)
Cognitive Radio (CR) HotSpot is a typical example of commercialized Dynamic Spectrum Access (DSA) in which a Wireless Service Provider (WSP) provides CR end-users access to its local-area network. A WSP temporarily leases licensed channels from the primary licensees via spectrum auction, and subleases them to CR end-users or customers, each demanding a(More)
In the recently-suggested dynamic spectrum allocation policy of cognitive radio networks [1]–[3], sensing/monitoring of spectrum availability is identified as a key requirement. To meet this requirement we address an important MAC-layer sensing issue: which of proactive and reactive sensing is more energy-efficient? An algorithm is proposed to dynamically(More)
Spectrum sensing is essential to the realization of spectrum agility in cognitive radio (CR) networks. Although fundamental tradeoffs and theoretical limits associated with spectrum sensing have been studied extensively, there have been very few experimental studies focused on building a spectrum “sensor” with commercial off-the-shelf devices. We have(More)
We consider the problem of opportunistically scheduling low-priority tasks onto underutilized computation resources in the cloud left by high-priority tasks. To avoid conflicts with high-priority tasks, the scheduler must suspend the low-priority tasks (causing waiting), or move them to other underutilized servers (causing migration), if the high-priority(More)
Static spectrum allocation has resulted in low spectrum efficiency in licensed bands and poor performance of radio devices in crowded unlicensed bands. To remedy these problems, we exploit the concept of “spectral agility” such that radio devices can dynamically utilize idle spectral bands. We establish a mathematical model for the performance gain made by(More)
In IEEE 802.22 Wireless Regional Area Networks (WRANs), each Base Station (BS) solves a complex resource allocation problem of simultaneously determining the channel to reuse, power for adaptive coverage, and Consumer Premise Equipments (CPEs) to associate with, while maximizing the total downstream capacity of CPEs. Although joint power and channel(More)