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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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