pres cmpe 300 project
TRANSCRIPT
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Utility Based Scheduling inCognitive Radio Networks
Term ProjectCmpE-300 Analysis of Algorithms
Spring 2009Computer Engineering,Boazii University, Istanbul
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Outline
Wireless networks FDMA, TDMA, CDMA
Dynamic Spectrum Access
Cognitive Radio Networks
Problem Formulation
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Cellular Networks
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Cellular Networks
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Cellular Networks
MSC: Mobile Switching Center
How do different mobile stationscommunicate simultaneously with the BS?
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Frequency Division MultipleAccess (FDMA)
Each mobile device tunesto a frequency band
Analogous to peopletalking in different rooms
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Frequency Division MultipleAccess (FDMA)
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Time Division Multiple Access
(TDMA) Each mobile device transmits data in a different time slot
Analogous to people talking one by one
GSM: Combination of FDMA and TDMA 25 MHz bandwidth divided into 124 carrier
frequencies of 200 KHz bandwidth Each carrier frequency divided into 8 time slots
using TDMA
3G licenses: Type-A: 40 MHz, Turkcell Type-B: 35 MHz, Vodafone Type-C: 30 MHz, Avea
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Time Division Multiple Access(TDMA)
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Code Division Multiple Access(CDMA)
Analogous to people talking indifferent languages
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Dynamic Spectrum Access
(DSA) PROBLEM : Underutilized spectrum
resources due to fixed assignmentstrategy
IDEA : Utilizing white spaces in thespectrum without disturbing licensedusers [1]
CHALLENGE : Sensing the environment,
detecting white spaces white spaces frequently change
by time and space Changing radio parameters on the
fly
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Frequency Allocation Charts In Turkey:
http://www.tk.gov.tr/Duzenlemeler/teknik/marfl/_marfl1.asp
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White Space Concept
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Cognitive Radio (CR) Concept
Initially proposed by Mitola [2]
Next step evolution of Software Defined
Radio (SDR)
Cognitive Radio (CR): Intelligent devicesthat can [2]: Sense and autonomously reason
about their environment Adapt their communication
parameters accordingly Realize DSA concept
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Terminology Primary User (PU):
Licensed user Has exclusive rights for the
spectrum
Secondary User (SU): Unlicensed user Opportunistically utilizes the white
spaces Has to vacate the spectrum band
as soon as a PU appears Also called cognitive user
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IEEE 802.22 Network Architecture
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Research Problem totalNetworkUtility : Total number of SUs that are
satisfied in terms of throughput
Maximize (totalNetworkUtility)
subject to
No interference is imposed on the PUs
Reliable communication with the CBS is achievedNo collisions occur among the SUs
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Research Problem Terminology N: Total number of SUs
F: Total number of frequencies
T: Total number of time slots
Uif = Maximum number of packets that can be transmitted by user i to theCBS using frequency f
(in a time slot)
t i = Throughput (data rate) of SU i
g(t i )=The level of satisfaction of SU i from throughput t i
t imin = Minimum throughput required by SU i
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t timeslot in f frequencywithtransmitsiuser if X ift
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Problem Formulation
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totalNetworkUtility
Each SU is assigned at least 1 time slot
At most 1 user isassigned a certaintime slot and frequency pair
Throughput of SU i
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Problem Formulation
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Problem Formulation
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References
[1] Akyildiz, I., W. Lee, M. Vuran, and S. Mohanty, NeXtgeneration/dynamic spectrum access/cognitive radiowireless networks: A survey , Computer Networks, Vol.50, No. 13, pp. 2127-2159, 2006.
[2] Mitola, J., Cognitive Radio: AnIntegrated Agent Architecture for
Software Defined Radio, Doctor of
Technology, Royal Institute of Technology(KTH), Stockholm, Sweden, 2000.
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Questions?
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