Post on 03-Apr-2018
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Opportunities and Challenges of
Cognitive Radio Networks
Loredana ArienzoLoredana Arienzoloredana.arienzo@jrc.it
EC Joint Research Center,
Italy
Ispra - June 29, 2009
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Fixed Spectrum Assignment
300 GHz
3 kHz
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Fixed Spectrum Util ization
Amplitu
de
(dBm)
Heavy Use Heavy Use
Medium UseSparse Use
Frequency3 kHz300 GHz
Spectrum use is inefficient
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Cognitive Radio Networks
Dynamic Spectrum Allocation Networks
Dynamic SpectrumDynamic SpectrumAllocationAllocation
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Cognitive Radio
Key enabling technology for Dynamic Spectrum Access
A Cognitive Radio is a radio that can change its transmitter
parameters based on interaction with the environment in
which it operates (FCC2005)
Capability to use or share the spectrum in an opportunistic
manner -> BANDWIDTH HARVESTING
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Recent Standardization Activity - ETSI
ETSI created a Technical Committee for Reconfigurable Radio
Systems (RRS) in January 2008 to study the feasibility of
standardization related to Software Defined Radio (SDR) and
Cognitive Radio
Feasibi lity report expected by Jan 2010
Committee focus on systems aspects, equipment architecture,
functional architecture
Clear focus on Public Safety application, recognizing
requirement for SDR and CR from Defence and Public Safety
segments
TC RRS
Systems
Aspects
Equipment
Architecture
Functional
Architecture
and CPC
Public
Safety
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Some Concepts
Primary Network An existing network infrastructure which has an access right to a
certain spectrum band.
e.g., Common cellular systems and e.g., Common cellular systemsand TV broadcast networks.
Primary User (or Licensed User) Has a license to operate in a certain spectrum band.
Secondary Network (or Unlicensed Network) Does not have license to operate in a desired band.
Hence, the spectrum access is allowed only in an opportunisticmanner !
Secondary User (or Unlicensed User ) has no spectrum license
Hence, additional functionalities are required to share the licensedspectrum band !
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Cognitive Radio NetworkArchitecture
PrimaryBase-station
PrimaryUser
Primary Network
Licensed Band I
Unlicensed Band
Licensed Band II
Cognitive Radio Network
CRNetworkAccess
CRUser
Spectrum Band
Primary
NetworkAccess
CRBase-station
Other
CRNetworks
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
PrimaryBase-station
PrimaryUser
Primary Network
Licensed Band I
Unlicensed Band
Licensed Band II
Cognitive Radio Network
CRAd Hoc
Access
CRUser
Spectrum Band
Primary
NetworkAccess
CR Ad Hoc Network Architecture
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Research Challanges
Spectrum Sensing:A CR user should monitor the available
spectrum bands and detect unused spectrum or spectrumholes avoiding harmful interference with other users.
Spectrum Decision:A CR user can select the best availablechannel to meet the communication requirements.
Spectrum Sharing: A CR user should coordinate theaccess to this channel to prevent collision of multiple users.
Spectrum Mobility:CR users should vacate the channel
when a licensed user is detected.
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Spectrum Holes
Time
FrequencySpectrum Holes
Power
Spectrum occupied
by Licensed usersSensing issue
PU Detection(Sensing issue)
Channel Switching
(Hardware issue)
Resume
Communication(Sharing issue)
Sharing issue
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Receiver Uncertainty Problem
Primary User(Transmitter)
Primary
TransmitterRange
Primary User
CRTransmitter
Range
Interference
CR User
Cannotdetect the
PU transmitter
Interference due to uncertainty of receiver location
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Shadowing Problem
Hidden Terminal Problem due to Shadowing
CR
TransmitterRange
Primary User(Transmitter)
CR User
PrimaryTransmitter
Range
Primary User
Interference
Cannotdetect the
PU transmitter
Primary User
CR User
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Solution: Cooperation
Primary
User
PU
Multi-pathfading
Weak signals
are received
due to themulti-path
fading maynot detect the
PU
Shadowing
Cannot detect
the PU due tothe obstacles
Detect theprimary usercorrectly
By exchanging theirsensing information,
CR users can detect
the PU under fading
and shadowing
environments
CR User 22
CR User 3
CR User 1
BUS
IDLE
IDLE
BUSYBUSY
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Cognitive Radio Research
Fundamental research and algorithms based on:
Information and Coding Theory
Relay cooperation, User Cooperation, Coding techniques for
cooperation, Collaborative MIMO techniques
Signal Processing
Collaborative signal processing, Signal design for spectrum
sharing, Interference avoidance, Distributed sensing algorithms Game Theory
Microeconomics and pricing based schemes for spectrum
sharing, negotiation and coexistence, Incentive mechanisms for
cooperation
MAC and Networking Algorithms
Discovery protocols, Etiquette protocols, Self-organization
protocols, Multihop routing
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Spectrum Sensing
Objectives:
Opportunity discovery with interference avoidance
PU Detection
Measures the received signal level and determines the
presence of transmissions
Our concerns:Asymptotic approximations are useful only when enough
data is available, which is not always possible due to
time constraints, the nature of the signal or the
measurement setting
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Spectrum Sensing
InterferenceTemperatureManagement
TransmitterDetection
Spectrum Sensing
ReceiverDetection
Matched FilterDetection
EnergyDetection
CyclostationaryFeature Detection
Classification of Spectrum Sensing TechniquesClassif ication of Spectrum Sensing Techniques
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Our Approach: Bootstrap Hypothesis Test
We assume both PU and CR users operating over a wideband channel.
We consider the IEEE 802.15.4a channel model 3, i.e. a LOS indooroffice. We have f =8GHz and f=500MHz (i.e. T=T=2ns).
2 3 4 5 6 7 8
x 109
0
0.5
1
1.5
2
2.5
x 104
Frequency (Hz)
|H|2
IEEE 802.15.4a Channel Frequency Response
L. Arienzo, Bootst rapping the Spectrum in Ultra Wide-Band Cogniti ve Radio Networks , 2nd Int. Workshop on Cognit ive Radioand Advanced Spectrum Management (CogArt09) in conjunct ion with Wireless VITAE 2009, Aalborg, May 18-20, 2009
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Our Approach: Bootstrap Hypothesis Test
probability of false alarm equal to 0.01;
noise power level is v = 1;
wild bootstrap with 1000 samples for the bootstrap simulation.
Density of the true statistic, its wild bootstrap approximation, and the
corresponding asymptotic normal density
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Cognitive radio networks require a large of amount of
network (and channel) state information to enable efficient
Discovery Self-organization
Cooperation Techniques
In addition to advances in cognitive radio technology, Network
Architectures and Information Aids that support these arerequired
Coordination mechanisms for coexistence and cooperation
Network architectures
Spectrum Servers to advise/mediate sharing
Information aids
Spectrum Coordination Mechanisms (Cognitive Control
Channel)
Concluding Remarks
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Workshop on Dynamic spectrum management and cognitive radio for the public safety June 29, 2009
Cognit ive Radio Applications
Sensor Network
Mapping
Environment monitoring
Event tracking
Localization of Mobile Devices
Location not only allows people to find you, but also allowsyou to find people
Primary location applications: navigator surveyor, tracking
busses, taxis, fleets and people, emergency, mil itary,
industrial or business operators