Cognitive Radio Networks (CRN)

Speaker: You-Min LinAdvisor: Dr. Kai-Wei KeDate: 2011/04/25Cognitive Radio Networks (CRN)11OutlineIntroduction

Basic cognitive cycle

MAC Layer Design

Applications

Conclusions and Future

Reference

2What is Cognitive Radio(CR)Mitolas definition (1999):Software radio that is aware of its environment and its capabilities Alters its physical layer behaviorCapable of following complex adaptation strategiesA radio or system that senses, and is aware of, its operation environment and can dynamically and autonomously adjust its radio operating parameters accordingly3What 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 manner4What is Cognitive Radio Networks (CRN) Primary Network

Primary User (or Licensed User)

Secondary Networks (or Unlicensed Network)

Secondary User (or Unlicensed User)

5Cognitive Radio Networks (CRN) 6

TV White SpaceDigital 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

Spectrum utility (1/3) Spectrum Scarcity

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Spectrum utility (2/3) 9

Spectrum utility (3/3) 10

3kHz~300GHzSpectrum hole11

Worldwide Regulatory AgenciesFCC 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 Bandshttp://edocket.access.gpo.gov/2009/pdf/E9-3279.pdf12FCC 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 channelsand are further divided into 2 types: Mode I and Mode II.

13FCC 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. 14FCC 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.

15Some Fun

16Some Fun

17Some Fun18

Basic cognitive cycle19

Main functionsSpectrum sensingDetecting unused spectrum

Spectrum managementCapturing the best available spectrum

Spectrum mobilityMaintaining seamless communication during the spectrum transition

Spectrum sharingProviding fair spectrum scheduling method

20MAC Layer DesignThe basic building blocks for MAC Beaconing protocols and channel access protocols.

Multi-device beaconingSingle-device beaconing can lead to the potential interference between adjacent networks.

Channel reservation accessTo achieve high protocol efficiency and strict QoS provisioning.

21MAC Structure and Beaconing

22Single-device beaconingClient 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.

23Multi-device beaconingBeaconing 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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Channel selection 25

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.26Applications (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.27Conclusions and FutureFundamental research

Implementation

Government

28Reference29[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