Static spectrum allocation policies of the past have led to an artificial spectrum scarcity problem. The ideal solution is dynamic spectrum sharing, where wireless devices dynamically access spectrum matching their demands and share spectrum with peers to minimize interference.
Realizing dynamic spectrum sharing in practical systems, however, faces significant challenges. First, the nature of dynamic access, combined with the strong inter-dependency across devices, leads to frequent and unpredictable fluctuations in resulting spectrum usage. Unaddressed, these fluctuations will translate into significant loss in both network and user performance. Second, managing spectrum in a large-scale dynamic system is highly challenging due to the strong inter-dependency across devices caused by complex radio interference. Third, as various wireless devices become densely populated, heterogeneous devices must coexist. The heterogeneity in power profiles, protocols and network architecture makes device coordination, interference management and access scheduling highly challenging. Finally, we must provide a secure spectrum access environment where unauthorized spectrum usage can be detected and removed.
In this PhD work, we design and implement novel algorithms and systems for dynamic spectrum sharing to overcome these challenges. Our designs consider several key application and network scenarios. First, we develop a frequency-domain spectrum sharing system which provides decentralized, robust and high-bandwidth wireless transmissions. This is particularly desirable for demanding media applications which require continuous access to spectrum. Second, for densely deployed devices, we develop a guardband configuration system to suppress the strong inter-device interference at frequency boundaries. Third, we extend our system to large-scale networks and develop an allocation framework to distribute spectrum efficiently. Fourth, we consider hierarchical spectrum sharing and design cross-network WiMAX scheduling algorithms for efficient WiMAX and WiFi coexistence. Finally, we enforce spectrum distribution by designing a secure dynamic spectrum system that can verify authorized spectrum access and identify spectrum misuse. Together, we provide a systematic design of reliable, efficient and enforceable dynamic spectrum sharing.
|Commitee:||Belding, Elizabeth M., Zhao, Ben Y.|
|School:||University of California, Santa Barbara|
|School Location:||United States -- California|
|Source:||DAI-B 72/08, Dissertation Abstracts International|
|Keywords:||Complex radio interference, Inter-dependency, Spectrum matching, Spectrum sharing, Static spectrum allocation|
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