The Myth of Spectrum Scarcity:

Hybrid Networks and Opportunistic Access to the Airwaves

eCommEmerging Communications Conference

October 30, 2009

Michael CalabreseDirector, Wireless Future ProgramNew America Foundationcalabrese@newamerica.net

Wireless Future Program

Mission: Pervasive Connectivity• Universal• Ubiquitous• Affordable

Means: Openness• Open Spectrum• Open Networks• Open Technologies

Conventional Wisdom: Spectrum is Scarce

Exploding Demand for Mobile Data- iPhone: Canary in the Spectrum Coal Mine

- Total US mobile data demand: 16 to 366 terabytes by 2013 (Cisco)

Estimated Growth in Monthly Data Consumption from Smartphones

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Reality: Spectrum Licenses are Scarce

Reality: Spectrum Capacity is Abundant (90% not in use)

“The spectrum is completely, unbelievably underutilized. It’s terribly inefficient and grossly unfair

to rural America”– Tri-County Telephone Co-Op, Wyoming

More Conventional Wisdom:Meet Mobile Data Demand

with Spectrum Auctions

US Wireless Industry (CTIA): Petitions FCC for 800 Additional MHz of exclusively-licensed spectrum

This is based on ITU Projections that advanced market economies require total allocations of roughly 1,300 MHz by 2015 and 1,720 by 2020 (vs. 500 MHz today in U.S.)

ITU Spectrum Requirements for Competitive Markets is Higher Still

Source: ITU, Estimated total spectrum requirements for future development of IMT-2000 and IMT-Advanced (2006).

More Spectrum is Just One Part of the Solution to Exploding

Mobile Data Demand

Increase spectrum access Shrink cell sizes (spectrum re-use) More effective use of wired backhaul

(offload data traffic) More efficient/cooperative wireless

architectures and technologies

Exclusively-Licensed, Hub-Spoke, Tower-Based Model is

Not Sustainable . . . Clearing incumbents off 800+ MHz not feasible

Physical limits on cell capacity- ITU estimate assumes 4G at 75% of theoretical limit (Shannon’s Law)

Limits on how close carrier-owned transmitters and backhaul can be brought to individual users

- Total U.S. cell sites increased only 14% over past two years

. . . Nor Desirable . . . Most mobile data should flow short

distances over shared spectrum to consumer-owned or shared backhaul

Consumers should not pay for data transport over expensive carrier spectrum/infrastructure

Carriers evolve into ‘quality of service’ component of hybrid networks

- Consumers pay only for needed mobility, remote access and latency-sensitive aps

Carriers are Increasingly Offloading Data Traffic to WiFi

Signs of the Times: AT&T: 25.6 million WiFi connections

through June > double all of 2008. T-Mobile offering office and home service

that default to WiFi, potentially replacing wired lines (but charging for ‘free’!)

Devicescape survey: 81% of smartphone users prefer using WiFi for mobile browsing/email

Far More Spectrum Can be Freed Via Opportunistic Access by

Cognitive Radios Tragedy of the Anti-Commons:

Spectrum is infinitely renewable – bandwidth not used at any place/time is wasted.

A band can be ‘white’ (underutilized) and shared on a number of dimensions:• Geographically (not in use everywhere)• Time (not continually in use)• Spatially (in the air, not on the ground)• Angle of Reception (directional or ‘smart

antennas’)

Underlay: Sharing Underutilized Frequency Band

Example: WiFi Backhaul Shares Upper 5 GHz with Military Radar – Listen Before Talk Sensing

Overlay: Filling Unoccupied FrequenciesExample: TV Guard Bands (“White Space”)

TV WS: Opportunistic Access to ‘Swiss Cheese’ Spectrum

Majority of interleaved (TV WS) channels become useable on opportunistic, license-exempt basis if:-- Cognitive Radio: Occupied channel detection and frequency hopping via . . .

- Geolocate database: Lists permitted channels, or- Listen-Before-Talk Sensing

-- Low Power: - FCC (40 mW for mobile on channels adjacent to

DTV)- OfCom (variable power when rely on geo-database)

Some Benefits:- Spectrum efficiency: frequency re-use at low power- National availability (even in large Metro markets)- No permanent assignment channels: bands and access

conditions changeable with CR

FCC’s TV White Space Order Adopted Nov. 4, 2008: 5-0 Vote Unlicensed access to all unassigned

channels- Mobile: 40mW (or 50mW non-adjacent)- Fixed Access: 4 W (non-adjacent only)

Devices must have GPS & Check Location Against Online Database of Licensed transmitters

- Reliance on sensing/DFS unresolved

UK and EU ‘Digital Dividend’ OfCom (July ‘09): Adopts license-exempt

access to ‘interleaved’ channels by CRs relying on geo-permission database

ECC/CEPT Working Group (Oct. ‘09): Draft Report on technical and operational requirements for CR systems in the ‘white spaces’ (WG-SE43)

“[T]he digital dividend presents an opportunity to introduce a more flexible spectrum approach, giving Europe a competitive edge over other regions.” --EC Consultation Document, July ‘09

Future: Opportunistic Access

Let ‘Smart Radios’ Operate Around the Dinosaurs

• Clarify License Rights: Protect only incumbent services, not unused spectrum capacity

• Open unused spectrum for non-interfering use, millisecond to millisecond

Rules of the Road: Like Public Highways and Ocean Shipping Lanes, Exclusive Licenses are Inefficient for

Low-Power Use of the Airwaves

Next Steps to Open Spectrum

Inventory the Airwaves• In U.S., legislation pending to survey assigned

and actual uses, frequency-by-frequency, to identify ‘white spaces’ and where sharing is possible

• Actual use measurement & monitoring is key – and increasingly affordable

Add Available Frequencies to TV

White Space Database• Devices with GPS and/or sensing can identify open

frequencies locality by locality.• Software defined radio allows devices to

dynamically hop across a very wide range of frequencies: opportunistic access.

Market-Based Sticks & Carrots:

• Levy annual lease fees on all government and private license holders that do not open unused capacity for opportunistic sharing.

• At a minimum, require license holders to take micro-payments for unused bandwidth.