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Cognitive Radio Networks Neil Tang 1/28/2009

Explore the motivation, definition, network architecture, and critical issues of cognitive radio networks. Learn about MAC layer and upper layer challenges, as well as cross-layer optimization.

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Cognitive Radio Networks Neil Tang 1/28/2009

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  1. Cognitive Radio NetworksNeil Tang1/28/2009 CS541 Advanced Networking

  2. Outline • Motivation • Definition • Network Architecture • Characteristics • Critical Issues • MAC layer Challenges • Upper Layer Challenges • Cross-layer Optimization CS541 Advanced Networking

  3. Motivation If the static approach is used to manage the spectrum: • On one hand, certain parts of the spectrum, such as the 2.4GHz band and the 5GHz band, are heavily used by various wireless devices. • On the other hand, a significant amount of spectrum remains under-utilized or even not utilized at all. CS541 Advanced Networking

  4. Cognitive Radio • “A Cognitive Radio is a radio that can change its transmitter parameters based on interaction with the environment in which it operates.” • A cognitive radiois able to sense and analyze the spectrum, and make a decision on the selection of the spectrum band, data rate and so on. CS541 Advanced Networking

  5. Network Architecture CS541 Advanced Networking

  6. Characteristics • Dynamic spectrum availability • Spectrum heterogeneity CS541 Advanced Networking

  7. Critical Issues • Spectrum sensing • Spectrum analysis: Characterize each spectrum band (transmission range, data rate, packet loss ratio, etc). • Spectrum mobility/handoff • Spectrum sharing: Spectrum allocation and access • Upper layer issues: routing and transport layer CS541 Advanced Networking

  8. MAC Layer Challenges • Centralized VS. distributed • Inter-network interference • Spectrum heterogeneity • Common Control Channel (CCC) and message exchange • Maximize throughput and achieve fairness • Minimize power consumption CS541 Advanced Networking

  9. Upper Layer Challenges • Route discovery: broadcast on a common channel or a set of channels. • Route selection is coupled with spectrum selection. • Re-route scheme • End-to-end rate depends on spectrum allocation. CS541 Advanced Networking

  10. Cross-layer Optimization Joint routing and spectrum sharing • Maximize the end-to-end rate. • Minimize the end-to-end delay and satisfy a given end-to-end rate requirement. CS541 Advanced Networking

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