Seminar Ec
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Transcript of Seminar Ec
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BY :
V SHRIDHAR
08EC78
GUIDE :
Dr. JOHN DSOUZA
COGNITIVE RADIO NETWORKS
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ORGANISATIONy Introduction
y Cognitive Radio System
y Characteristics of CRN
y Spectrum Hole Concept
y Cognition Cycle
y Wireless Ad hoc networks
y Cognitive Radio Networks
y Spectrum Management of CRAHNs
-- Spectrum sensing
-- Spectrum decision
-- Spectrum sharing
-- Spectrum mobility
y Summary
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INTRODUCTION
Overview :y Background of Cognitive Radio
y Concepts behind working
y Characteristics
y Cognitive Radio Networks
y Processes in CRN
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Few example pictures of Cognitive Radios
COGNITIVE RADIO
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FREQUENCY ALLOCATIONS-US
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y Most of the spectrums already allocated for licensed users
y Few, Small, unlicensed bands are left open
y
Wi-Fi/802.11, Bluetooth, digital cordless phones, 3G operateon unlicensed band
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COGNITIVE RADIO SYSTEM
y unlicensed users can access the licensed bands.
y Cognitive Radio
- Termed by Joseph Mitola in 1991
- Radio that includes a transmitter in which operating
parameters can be altered by software."
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Continued..
- An improved software-defined radio.
Fig : An example of cognitive radio system components
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SDR vs Cognitive Radio
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Continued..
y To access under-utilized licensed bands , Cognitive Radio has to
- identify the spectrum opportunities
- use the licensed spectrum with transmit power constraint
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Spectrum Hole Concept
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CHARACTERISTICS
y Cognitive capability
y Ability to sense the information
y Reconfigurability
y Dynamically programmable capability
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Cognitive Radio -- Smart and Alert
y Location
y Services available
y Interesting services
y Future requirements
y Pattern recognition
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HOW IS IT SMART??
Fig. : Cognition cycle
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Wireless Ad Hoc Networks
y Ad hoc means
- "for this, or for this situation on hand.
y Wireless ad hoc network
- self-organizing and self-configuring
y Most of the wireless devices use it
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Classification of CRN
y Infrastructure based CR networks
y Has a central network entity to coordinate communication .
Fig : An example of infrastructure based CR networks
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Classification..
y Cognitive radio ad hoc networks(CRAHNs)
y Infrastructure less network
y No central network entity
y Communication through Ad-Hoc connection
Fig : An example of CRAHNs
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Continued..
Fig : CRAHN architecture
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y Functions incorporated in CRAHNs
y Spectrum sensing
y Spectrum decision
y Spectrum sharing
y Spectrum mobility
Spectrum management
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ySpectrum sensing
y monitor the unused spectrumbands
y
spectrum availability information
Fig : Periodic spectrum sensing structure.
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ySpectrum decision
-To select the most appropriate band to QOS req.
Fig : Spectrum decision framework for cognitive radio networks
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ySpectrum Sharing
y perform channel selection and power allocation
Fig : Inter-Cell Spectrum Sharing Framework
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ySpectrum mobility
CR users are mobile
Spectrum mobility is required when:
Primary User is detected
CR user loses its connection
QoS requirements not met
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Patents over Cognitive Radio
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Summary
y Increasing spectrum usage problems
y Solution through cognitive radio concept
y CRN Architecture
y CRN Classifications
y Spectrum Management in CRN
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References
y Wikipedia
y www.howstuffworks.com
y Cognitive Radio Ad Hoc Networks 7 (2009) 810-836, Ian F.
Akyildiz , Won-Lee, Kaushik R. Chowdhury
y Akyildiz, I.F.; Won-Yeol Lee; Vuran, M.C.; Mohanty, S. A Surveyon Spectrum Management in Cognitive Radio Networks
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