As presented at eComm Europe, October 2009. Are we using radio spectrum efficiently? No. Is this likely to change? Not soon. "Smart" radios have the potential to support much more efficient and productive use of spectrum, but spectrum regulation is a political issue with well established stakeholders. What's more, our limited experiments with commons-based spectrum management have had widely differing results: WiFi, enormous success; UltraWideBand, disappointment. WiFi's success happened in "junk" spectral bands where established players weren't interested. That will be difficult to repeat, but Brough will describe some very simple physical principals of radio propagation which, when combined with the next five years of Moore's law progress in semiconductors, suggest a path forward that's very different from TV white spaces. Indeed, the most important result of regulatory decisions on UltraWideBand and TV white spaces is they validate the concept of secondary access.

1. A Wireless Tipping Point,
Open Spectrum Implications
Brough Turner
http://www.broughturner.com

2. 1920s consumer radio receivers
Philips 2501
Very early tech, i.e. primitive
Crystal, Regenerative, Tuned RF …
Poor selectivity, low sensitivity,
low stability
Tuned RF
Crystal
2

3. Radio Spectrum Occupancy
Urban areas, 30 MHz to 3 GHz. Above 3 GHz mostly vacant.
As measured by Shared Spectrum Company and the
University of Kansas Center for Research for the
NSF National Radio Network Research Testbed (NRNRT)
3

4. New York City
Unusually heavy communications during Republican National Convention
August 30 to September 3, 2004 brought spectrum occupancy up to 13%.
4

5. Most spectrum idle most of the time
806 – 928 MHz
Dublin Ireland Spectrum Occupancy Measurements
Collected On April 16-18, 2007
Shared Spectrum Company, www.sharedspectrum.com
5

6. Most spectrum idle most of the time
806 – 928 MHz
Dublin Ireland Spectrum Occupancy Measurements
Collected On April 16-18, 2007
Shared Spectrum Company, www.sharedspectrum.com
6

7. Most spectrum idle most of the time
806 – 928 MHz
Dublin Ireland Spectrum Occupancy Measurements
Collected On April 16-18, 2007
Shared Spectrum Company, www.sharedspectrum.com
7

8. Open Spectrum
Noise, Interference, Chaos … !
How could it work?
8

9. Open Spectrum
Noise, Interference, Chaos … !
How could it work?
Focus on Receiver Performance
9

10. Visible light analogy
Our vision system
(eyes + visual cortex)
= extremely efficient
400-790 THz receiver
The product of years
of evolution!
10

11. Spatial discrimination
For Humans:
~ 1/60th of a degree
11

12. Enormous knowledge base
Detailed catalog of the characteristics of most
potential visible light sources
12

13. Leveraging source motion
to increase received information …
13

14. 1920: Regulation made sense
14

15. 1920: Regulation made sense
2009: We’ve come a long way
15

16. 1920: Regulation made sense
2009: We’ve come a long way
Shared use of unlicensed spectrum
Enormous value creation
16

17. 1920: Regulation made sense
2009: We’ve come a long way
Shared use of unlicensed spectrum
Enormous value creation
Thermex Thermatron RF Dryers
17

18. Open spectrum prospects
Regulation Vested interests
TV White Spaces
Crippled for now…
18

19. Open spectrum prospects
Regulation Vested interests
TV White Spaces
Crippled for now…
What about higher frequencies?
19

20. Spectrum Myth
TV Spectrum is “beach front” spectrum
20

21. Spectrum Myth
TV Spectrum is “beach front” spectrum
Based on legacy technology, not physics!
Travels farther – No!
Goes thru walls – Not that different…
21

22. Refraction and reflections
More at shorter wavelengths
Multiple versions “Multipath”
22

23. MIMO: Multiple Input Multiple Output
Multiple paths improve link reliability and
increase spectral efficiency (bps per Hz),
range and directionality
23

24. Rich Indoor MIMO Multipath
Source: Fanny Mlinarsky, Octoscope
24

25. Municipal Multipath Environment
Source: Fanny Mlinarsky, Octoscope 25

26. 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
D-Link DAP-2553 Wavion Networks
26

27. Multiple radios per chip
Like CPU cores … Intel
2x2 MIMO – 2008
4x4 MIMO – 2010-11
then
Fujitsu
8 radios, 16 radios?, …
what to use the silicon
for?
Beam-forming ! AMD
27

28. Beamforming
2014: >200 Mbps Wi-Fi to >1 Km
at mass market prices ?
4x4 MIMO
with 12-16
antenna
elements
28

29. Beamforming
2014: >200 Mbps Wi-Fi to >1 Km
at mass market prices ?
4x4 MIMO
with 12-16
antenna
elements
29

30. 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
30

31. Wi-Fi 802.11y - 2008
Rich protocol set for “secondary access”
31

32. 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
32

33. Thank You
Brough Turner
broughturner@gmail.com
rbt@ashtonbrooke.com

34. 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/
34