White Space Networking: The Road Ahead
Ranveer Chandra
Microsoft Research
Challenge 1: Limited Capacity due to Growing Demand
24 HOURS
UPLOADED EVERY
60 SECONDS
20X - 40X
OVER THE NEXT
FIVE YEARS
*See Ericsson Press Release, quoting its President and Chief Executive Officer Hans Vestberg, April 13, 2010, available at
http://www.ericsson.com/thecompany/press/releases/2010/04/1403231
**. Federal Communications Commission, Staff Technical Paper, Mobile Broadband: The Benefits of Additional Spectrum, OBI Technical Paper No. 6 (Oct. 2010).
50 BILLION
CONNECTED DEVICES
BY 2020
35X
2009 LEVELS
BY 2014
Challenge 2: Limited Range for Universal BB Access
2 Billion
Internet Connected
Consumers
555 Million
Wired Broadband
Subscribers
*2010 Estimates: ITU World Telecommunications/ ICT Indicators database
943 Million
Wireless
Broadband
Subscribers
5 Billion
Cell Phones
Spectrum Policy Needs to Become More Nimble
Industry Forecasts of Mobile Data Traffic
50X
Traffic Relative to 2009
45X
40X
35X
Cisco
30X
Increasingly sophisticated
online databases that
automate spectrum allocation
and use.
Coda
25X
Yankee Group
20X
Average
15X
10X
5X
0X
2009
2010
2011
2012
2013
2014
Wideband radios with sensing,
channel notching,
suppression, bonding, and
other capabilities.
Our Ask of Policy Makers
What are TV White Spaces?
• TV band white spaces are gaps left between broadcast channels
• They occur in different places on different channels
Database Access Safeguards Incumbents from Interference –
This is No Free-For-All!
White Spaces
Database
White Spaces
Base Station
White Spaces
Client Device
TV White
Spaces Link
1. Devices only use the TV white spaces
channels specified by the database.
2. Devices are required to re-check the
database for the list of available channels.
3. Databases are prohibited from providing
devices access to the channels occupied by
incumbent operators (e.g., broadcasters).
4. Databases are required to maintain up-todate lists of protected operators.
5. Databases can block newly occupied
channels to prevent further white spaces
device access.
TV White Spaces Access
Powe
r
PU1
PU3
PU2
PU4
Frequency
•
•
•
•
•
Query the availability database
Transmit in “available frequencies”
Detect if primary user appears
Move to new frequencies
Adapt bandwidth and power levels
• Operation of unlicensed devices on
unused channels in the TV bands
 Protection for licensed services
 And some others
• Available channels identified via
 Geo-location capability
 Database access
Sample TV Band Channels Available for White Spaces Devices
UHF TV Bands Enable New Wi-Fi Opportunities
Capacity versus Range
350
TVWS
TVWS-Fixed
WLAN-2.4
WLAN-5
250
200
150
100
50
Range (meters)
1250
1200
1150
1100
1050
1000
950
900
850
800
750
700
650
600
550
500
450
400
350
300
250
200
150
100
50
0
10
Capacity (Mega bits per second)
300
Sub 1 GHz: Key to Ubiquitous Access
Wi-Fi , 5 GHz
This slide shows the results of simulating the coverage that could be achieved,
with 20% access point penetration, in a 1 km2 urban area, with 5K population,
in Fulham, London. The simulation was repeated for each of the three bands
Wi-Fi , 2.4 GHz
TV White Spaces, 600 MHz
Source: BT Innovate & Design
TV White Spaces Signals Travel Farther
Wi-Fi: 100 Meters
TV White Spaces: 400 Meters (with
increased flexibility, could be up to 8
kms or more)
Four times the distance; 16
times the area covered.
Same power comparing
2.4 GHz to 600 MHz. The
result is more bandwidth,
lower network costs, lower
power consumption.
TV White Spaces Signals Penetrate More Walls
•In a typical home, a Wi-Fi
signal can penetrate up to
two walls. At the same
power, a TV white spaces
signal can penetrate more
walls and obstacles,
enabling whole home
media distribution.
•This will simplify and
enrich in-home/in-building
networking opportunities.
Potential TV White Spaces Use Cases
• Utilizing long range characteristics
 Rural broadband
 Wide-coverage hotspots
 Bridge among small networks
 Sensor network
 Wireless surveillance system
 Cellular offloading
• Utilizing obstacle penetration/avoidance characteristics
 M2M –factory floor automation
 Indoor video distribution
 Device to device network
Greater Spectrum Sharing Opportunities Should Be Pursued
Who I am.
My willingness to pay/be paid for interference.
What I am.
My desired power output.
Where I am.
My out-of-band emission mask.
My knowledge of nearby transmissions (sensing).
My geolocation accuracy.
My spectrum tuning range.
My desired quality of service.
Am I moving.
Where I am going.
When I will get there.
How long I will be there.
© 2011 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions,
it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation.
MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.
What Is “Unlicensed” Spectrum Use?
• Devices are permitted to emit radio frequency energy without a specific grant
of a license.
 Devices still undergo certification and are subject to regulatory oversight.
 In the case of white spaces, databases operate under authority granted by
the relevant regulatory authority.
• Devices cannot cause harmful interference to licensed operations.
 And, they must accept interference from operation of an authorized radio
station.
• Licensed and unlicensed uses can readily coexist.
 Complementary business models
 Each supports the other (think Wi-Fi in a coffee shop)
The Value of Unlicensed Spectrum
• 20,339 unlicensed devices certified in 2.4 GHz spectrum band
 Three times more than any other band
• Wi-Fi devices will use more bandwidth than wired devices in 2015
• Mobile data offloaded to Wi-Fi from the networks of mobile operators
 Expected to reach almost 90% by 2015
• Wi-Fi accounts for over 50% of mobile user connections to the Internet
• The Internet of Things is coming …