Cognitive Radio and Its Applications-Xiao Zhengrong

8/14/2019 Cognitive Radio and Its Applications-Xiao Zhengrong

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Cognitive Radio and Its Applications


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OutlineBackgroundCognitive Radio DefinitionSpectrum Sharing Cognitive RadioApplications of Cognitive RadioChallenges of Cognitive Radio


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Backgroud Spectrum Scarcity

Spectrum drought ?How much spectrum is actually being used? Measured spectrum occupancy from 54 MHz to 3000

MHz

Average occupancy 5.2% Source, http://www.sharedspectrum.com

Dynamic Spectrum Access (DSA) for example, secondary users use vacant spectrum

with guaranteeing non-interference to primary users


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Cognitive Radio Definition

Cognitive radio Coined by Joseph Mitola late in 1999. Spectrum sharing cognitive radio: DSA Full cognitive radio: both DSA and ultimate SDR

CWT Cognitive Radio definition A transceiver that is aware of its environment and cancombine this awareness with knowledge of its userspriorities, needs, operational procedures, and governingregulatory rules. It adapt s to its environment and configuresitself in an appropriate fashion. The radio learn s throughexperience and is capable of generating solutions forcommunications problems unforeseen by its designers


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DefinitionCognitive radio is an intelligent wireless communication system

that is aware of its surrounding environment (i.e. outside world),and uses the methodology of understanding-by-building to learnfrom the environment and adapt its internal states to statisticalvariations in the incoming RF stimuli by making correspondingchanges in certain operating parameters (e.g., transmit power,carrier frequency, and modulation strategy) in real-time, with twoprimary objectives in mind: Highly reliable communications whenever and wherever needed; Efficient utilization of the radio spectrum.

Source:Cognitive Radio: Brain-Empowered Wireless Communications,S. Haykin


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Cognitive Radio


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Spectrum Sharing CR

IEEE Spectrum Sharing CR definition a radio frequency transceiver that is designed to

intelligently detect whether a particular segment of theradio spectrum is currently in use, and to jump into

(and out of, as necessary) the temporarily-unusedspectrum very rapidly without interfering with thetransmissions of other authorized users.

The most challenging technology is to agilelydetect signals even at low SNR sensitivity within awide frequency range


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Spectrum Sharing CR Architecture

Spectrum Sharing CR prototype is developed on a CellBroadband Engine powered Playstation 3 installed withGNU RadioFocus on signal detection and classification algorithms


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Applications of Cognitive Radio


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Intelligent allocation of resources andprioritization of tasks: Based on battery life, reduce the load on the

processor If a voice call comes through cache the

streaming audio download.


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Public Safety Applications


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Public Safety Communication SystemRequirements Rapidly deployable Support multiple services such as voice, data, etc.

efficiently Reliable Interoperable

aim at providing universal interoperable communicationservice of voice and data in public safety domain.


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ChallengesHidden Node ProblemHeterogeneous System Design Available channels: do not share the same propagation characteristics

have different bandwidths change with timeFrequency Assignment

Find Common broadcast channel Find Frequency assignment for nodesNegotiation of Resources


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Cognitive Radio will enable significantefficiencies in the use of radio spectrum butthere are a number of significant challenges

that need to be overcome before we canrealize full cognition in a radio system.


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Thank you!

Cognitive Radio and Its Applications-Xiao Zhengrong

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