[PPT] - Cognitive Radio Networks (CRN) Speaker: You-Min Lin Advisor: Dr. PowerPoint Presentation

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Speaker: You-Min Lin Advisor: Dr. Kai-Wei Ke Date: 2011/04/25

Cognitive Radio Networks (CRN)

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Ou Outl tlin ine

 Introduction  Basic cognitive cycle  MAC Layer Design  Applications  Conclusions and Future  Reference

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Wh What at is is Co Cogni niti tive e Ra Radi dio(

(CR)

CR)

 Mitola’s definition (1999):

 Software radio that is aware of its environment and its

capabilities

 Alters its physical layer behavior  Capable of following complex adaptation strategies  “A radio or system that senses, and is aware of, its operation

environment and can dynamically and autonomously adjust its radio operating parameters accordingly”

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Wh What at is is Co Cogni niti tive e Ra Radi dio(

(CR)

CR)

 A “Cognitive Radio” is a radio that can change its transmitter

parameters based on interaction with the environment in which it operates (FCC’2005)

 Capability to use or share the spectrum in an opportunistic

manner

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What i hat is Co s Cogniti gnitive Radio Ne e Radio Netw twor

rks (C

ks (CRN) RN)

 Primary Network  Primary User (or Licensed User)  Secondary Networks (or Unlicensed Network)  Secondary User (or Unlicensed User)

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Cog

gni

niti tive e Ra Radi dio

Netw

twork

rks

s (CRN RN) )

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TV Wh Whit ite S e Spac ace

 Digital TV Broadcasting systems have freed up channels used

in the analog TV frequency bands. These vacated channels are called “TV white space”.

 The economic potential for the TV white spaces was

estimated at $100 billion.

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Spec ectru trum m uti utilit ity y (1/ 1/3) 3)

 Spectrum Scarcity

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Spec ectru trum m uti utilit ity y (2/ 2/3) 3)

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Spec ectru trum m uti utilit ity y (3/ 3/3) 3)

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 3kHz~300GHz

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Spec ectru trum m hol

le

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Wor

rldw

dwid ide e Reg egul ulat ator

ry

y Agen enci cies es

 FCC in the US, Office of Communications (Ofcom) in the

UK and Electronic Communication Committee (ECC) of CEPT in Europe.

 On February 17, 2009, the FCC released the final rules for

“Unlicensed Operation in the TV Broadcast Bands”

 http://edocket.access.gpo.gov/2009/pdf/E9-3279.pdf

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FCC “Unlicensed Operation in the TV Broadcast Bands” (1/3)

 TV Band Devices (TVBDs) can only operate on channels that are

not adjacent to an incumbent TV signal in any channel between 2 and 51 except 3,4 and 37

 TVBDs are divided into two categories:

 Fixed

 Higher power (< 4W)  Must have a geolocation capability, capability to retrieve list of available

channel from an authorized database, and a spectrum sensing capability.  Personal/portable (channels 21-51(except 37)

 a maximum of 100mW on non-adjacent channel and 40mW on adjacent

channels

 and are further divided into 2 types: Mode I and Mode II.

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FCC “Unlicensed Operation in the TV Broadcast Bands” (2/3)

 Sensing is a mandatory function for all TVBDs.  A channel must be sensed for 30 seconds before determining

if it is available for use by a TVBD.

 Once Operation has started on a channel, sensing must be

done at least once every 60 seconds and if a wireless microphone is detected the channel must be vacated within 2 seconds.

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FCC “Unlicensed Operation in the TV Broadcast Bands” (3/3)

 Geolocation means must be present in all fixed and Mode II

device (+/- 50 meters)

 Safe harbor channels for wireless microphone usage are

defined in the 13 major metropolitan market to be the first available channel on either side of Channel 37.TVBDs cannot

perate on these channels.

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Som

me

e Fun un

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Som

me

e Fun un

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Som

me

e Fun un

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Ba Basi sic c co cogni niti tive e cy cycl cle

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Mai ain n fun unct ctio ions ns

 Spectrum sensing

 Detecting unused spectrum

 Spectrum management

 Capturing the best available spectrum

 Spectrum mobility

 Maintaining seamless communication during the spectrum transition

 Spectrum sharing

 Providing fair spectrum scheduling method

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MAC La Layer er De Desi sign

 The basic building blocks for MAC

 Beaconing protocols and channel access protocols.

 Multi-device beaconing

 Single-device beaconing can lead to the potential interference

between adjacent networks.

 Channel reservation access

 To achieve high protocol efficiency and strict QoS provisioning.

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MAC Str truc uctur ture e an and B d Bea eaco coni ning ng

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Sin ingle-de device vice bea eaco coni ning ng

 Client A and C becomes hidden terminal to each other. As a

result, the channel reservation and QP scheduled for client A and C will be disrupted.

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Mul ulti ti-de device vice bea eaco coni ning ng

 Beaconing Client A and C devices exchange channel

reservation information and QP schedule across network A and B periodically. Therefore, collision on channel reservation and QP is minimized.

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Chan anne nel sel selec ecti tion

n

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Ap Applic icati ations

ns (1/

1/2) 2)

 Robust delivery of High Definition Video inside home and

across multiple walls.

 The benefit of TVWS:

 Better propagation characteristics and therefore increased range

and robustness, in comparison to higher frequencies.

 The ability to operate at lower power-levels for a given range

would result in better energy efficiencies.

 Additional spectrum in the TVWS helps deal with overcrowding

f ISM bands.

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Ap Applic icati ations

ns (2/

2/2) 2)

 Robust coverage inside buildings and across campuses for wireless data

applications

 Enhanced range for municipality, community and rural Internet access.  Enhanced coverage for smart service and remote machine-to-machine

and RFID deployments.

 New interactive applications for TV broadcasters, such as weather and

news updates, upcoming program previews, interactive advertisements and games and web access.

 Enhanced range, robustness and quality for emergency-response and

public service communication networks.

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Con

ncl

clusio usions ns an and F d Futu uture

 Fundamental research  Implementation  Government

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Ref efer eren ence ce

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