Utilization and fairness in spectrum assignment for opportunistic spectrum access
Mobile Networks and Applications
NeXt generation/dynamic spectrum access/cognitive radio wireless networks: a survey
Computer Networks: The International Journal of Computer and Telecommunications Networking
White space networking with wi-fi like connectivity
Proceedings of the ACM SIGCOMM 2009 conference on Data communication
Dynamic spectrum access in DTV whitespaces: design rules, architecture and algorithms
Proceedings of the 15th annual international conference on Mobile computing and networking
Mining spectrum usage data: a large-scale spectrum measurement study
Proceedings of the 15th annual international conference on Mobile computing and networking
Optimal Transmission Strategies for Dynamic Spectrum Access in Cognitive Radio Networks
IEEE Transactions on Mobile Computing
Supporting demanding wireless applications with frequency-agile radios
NSDI'10 Proceedings of the 7th USENIX conference on Networked systems design and implementation
Device-to-device communication as an underlay to LTE-advanced networks
IEEE Communications Magazine
Full length article: Empirical time and frequency domain models of spectrum use
Physical Communication
Decentralized cognitive MAC for opportunistic spectrum access in ad hoc networks: A POMDP framework
IEEE Journal on Selected Areas in Communications
Realizing the future of wireless data communications
Communications of the ACM
Forty data communications research questions
ACM SIGCOMM Computer Communication Review
Building efficient spectrum-agile devices for dummies
Proceedings of the 18th annual international conference on Mobile computing and networking
The effectiveness of opportunistic spectrum access: a measurement study
IEEE/ACM Transactions on Networking (TON)
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Dynamic spectrum access networks are designed to allow today's bandwidth hungry "secondary devices" to share spectrum allocated to legacy devices, or "primary users." The success of this wireless communication model relies on the availability of unused spectrum, and the ability of secondary devices to utilize spectrum without disrupting transmissions of primary users. While recent measurement studies have shown that there is sufficient underutilized spectrum available, little is known about whether secondary devices can efficiently make use of available spectrum while minimizing disruptions to primary users. In this paper, we present the first comprehensive study on the presence of "usable" spectrum in opportunistic spectrum access systems, and whether sufficient spectrum can be extracted by secondary devices to support traditional networking applications. We use for our study fine-grain usage traces of a wide spectrum range (20MHz--6GHz) taken at 4 locations in Germany, the Netherlands, and Santa Barbara, California. Our study shows that on average, 54% of spectrum is never used and 26% is only partially used. Surprisingly, in this 26% of partially used spectrum, secondary devices can utilize very little spectrum using conservative access policies to minimize interference with primary users. Even assuming an optimal access scheme and extensive statistical knowledge of primary user access patterns, a user can only extract between 20-30% of the total available spectrum. To provide better spectrum availability, we propose frequency bundling, where secondary devices build reliable channels by combining multiple unreliable frequencies into virtual frequency bundles. Analyzing our traces, we find that there is little correlation of spectrum availability across channels, and that bundling random channels together can provide sustained periods of reliable transmission with only short interruptions.