Speaker: You-Min Lin Advisor: Dr. Kai-Wei Ke Date: 2011/04/25
Cognitive Radio Networks (CRN) 1
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Outline Introduction Basic cognitive cycle MAC Layer Design
Applications Conclusions and Future Reference 2
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What is Cognitive Radio(CR) Mitolas 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 3
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What is Cognitive Radio(CR) 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 4
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What is Cognitive Radio Networks (CRN) Primary Network Primary
User (or Licensed User) Secondary Networks (or Unlicensed Network)
Secondary User (or Unlicensed User) 5
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Cognitive Radio Networks (CRN) 6
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TV White Space 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. 7
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Spectrum utility (1/3) Spectrum Scarcity 8
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Spectrum utility (2/3) 9
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Spectrum utility (3/3) 10 3kHz~300GHz
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Spectrum hole 11
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Worldwide Regulatory Agencies 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
12
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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. 13
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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. 14
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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 operate
on these channels. 15
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Some Fun 16
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Some Fun 17
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Some Fun 18
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Basic cognitive cycle 19
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Main functions 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 20
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MAC Layer Design 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. 21
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MAC Structure and Beaconing 22
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Single-device beaconing 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. 23
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Multi-device beaconing 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. 24
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Channel selection 25
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Applications (1/2) 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 of ISM bands. 26
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Applications (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. 27
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Conclusions and Future Fundamental research Implementation
Government 28
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Reference 29 [1] S. Haykin, Cognitive radio: Brain-empowered
wireless communications, IEEE Journal on Selected Areas in
Communications, pp. 201-220, 2005. [2] Ecma 392, MAC and PHY for
Operation in TV White Space , Dec.2009. [3] Carlos Cordeiro, Kiran
Challapali, and Dagnachew Birru, IEEE 802.22: An Introduction To
The First Wireless Standard Based On Cognitive Radios, JOURNAL OF
COMMUNICATIONS, VOL. 1, NO. 1, APRIL 2006. [4] I. F. Akyildiz et
al., NeXt Generation/Dynamic Spectrum Access/Cognitive Radio
Wireless Networks: A Survey, Comp. Networks J., vol. 50, Sept.
2006, pp. 212759