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A Wireless Tipping Point, Open Spectrum Implications Brough Turner http://www.broughturner.com
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A Wireless Tipping Point, Open Spectrum Implications
Brough Turner
http://www.broughturner.com
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1920s consumer radio receivers
� Very early tech, i.e. primitive
� Crystal, Regenerative, Tuned RF …
� Poor selectivity, low sensitivity, low stability
Crystal
Tuned RF
Philips 2501
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Radio Spectrum Occupancy
As measured by Shared Spectrum Company and the
University of Kansas Center for Research for the
NSF National Radio Network Research Testbed (NRNRT)
Urban areas, 30 MHz to 3 GHz. Above 3 GHz mostly vacant.
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New York City
Unusually heavy communications during Republican National Convention
August 30 to September 3, 2004 brought spectrum occupancy up to 13%.
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Most spectrum idle most of the time
Dublin Ireland Spectrum Occupancy MeasurementsCollected On April 16-18, 2007Shared Spectrum Company, www.sharedspectrum.com
806 – 928 MHz
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Most spectrum idle most of the time
Dublin Ireland Spectrum Occupancy MeasurementsCollected On April 16-18, 2007Shared Spectrum Company, www.sharedspectrum.com
806 – 928 MHz
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Most spectrum idle most of the time
Dublin Ireland Spectrum Occupancy MeasurementsCollected On April 16-18, 2007Shared Spectrum Company, www.sharedspectrum.com
806 – 928 MHz
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Open Spectrum
� Noise, Interference, Chaos … !
How could it work?
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Open Spectrum
� Noise, Interference, Chaos … !
How could it work?
� Focus on Receiver Performance
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Visible light analogy
Our vision system (eyes + visual cortex) = extremely efficient 400-790 THz receiver
� The product of years of evolution!
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Spatial discrimination
� For Humans:~ 1/60th of a degree
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Enormous knowledge base
� Detailed catalog of the characteristics of most potential visible light sources
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Leveraging source motion
to increase received information …
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1920: Regulation made sense
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1920: Regulation made sense
� 2009: We’ve come a long way
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1920: Regulation made sense
� 2009: We’ve come a long way
� Shared use of unlicensed spectrum
� Enormous value creation
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1920: Regulation made sense
� 2009: We’ve come a long way
� Shared use of unlicensed spectrum
� Enormous value creation
Thermex Thermatron RF Dryers
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Open spectrum prospects
Regulation � Vested interests
TV White Spaces
� Crippled for now…
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Open spectrum prospects
Regulation � Vested interests
TV White Spaces
� Crippled for now…
What about higher frequencies?
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Spectrum Myth
TV Spectrum is “beach front” spectrum
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Spectrum Myth
TV Spectrum is “beach front” spectrum
� Based on legacy technology, not physics!
� Travels farther – No!
� Goes thru walls – Not that different…
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Refraction and reflections
More at shorter wavelengths
� Multiple versions � “Multipath”
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MIMO: Multiple Input Multiple Output
� Multiple paths improve link reliability and increase spectral efficiency (bps per Hz), range and directionality
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Rich Indoor MIMO Multipath
Source: Fanny Mlinarsky, Octoscope
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Municipal Multipath Environment
Source: Fanny Mlinarsky, Octoscope
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TVWS – Beach-front Property?
� MIMO antenna separation >= ½ wavelength
� 2.1 meters at 70 MHz
� 21 cm at 700 MHz
� But
� 2.5 cm for 5.8 GHz Wi-Fi
Wavion NetworksD-Link DAP-2553
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Multiple radios per chip
Like CPU cores …
� 2x2 MIMO – 2008
� 4x4 MIMO – 2010-11
then
� 8 radios, 16 radios?, …what to use the silicon for?
Beam-forming !
Intel
Fujitsu
AMD
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Beamforming
2014: >200 Mbps Wi-Fi to >1 Kmat mass market prices ?
4x4 MIMOwith 12-16 antenna elements
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Beamforming
2014: >200 Mbps Wi-Fi to >1 Kmat mass market prices ?
4x4 MIMOwith 12-16 antenna elements
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Gaining spectrum for open use
Seeking only “Secondary access”
� No interference with existing users
� Geographic database; Listen-before-talk
� License-exempt stations under positive control of a “lightly” licensed station
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Wi-Fi 802.11y - 2008
Rich protocol set for “secondary access”
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Open spectrum
Wireless tipping point ahead
� Focus on spectrum blocks above 3 GHz
� More access at 5 GHz (4.9-6 GHz)
� Anything between 6-10 GHz
� “Secondary use”
� Light licensing – 802.11y protocols
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Credits
� Beyond those noted on individual pages…� Images…� Office building facade: http://commons.wikimedia.org/wiki/User:Beek100
� Laptop icon: http://www.flickr.com/photos/ichibod/
� Microwave oven: http://www.flickr.com/photos/code_martial/
802.11n performance in the field� http://www.tomshardware.com/reviews/beamforming-wifi-ruckus,2390.html
� http://www.muniwireless.com/2009/02/23/80211n-dramatically-improves-outdoor-wifi/
