Improving Spectrum Utilization: Some Alternative Approaches

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Improving Spectrum UtilizationSome Alternative
Approaches
Consulting on wireless technology and policy

• Michael J. Marcus, Sc.D., FIEEE
• Director
• Marcus Spectrum Solutions, Paris, France
• mjmarcus_at_alum.mit.edu
• www.marcus-spectrum.com

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Macroeconomics of SpectrumWhy Increasing
Intensity of Spectrum Use is Vital

• Wireless technology and services are not just a
  1011/year industry
• Economic growth and efficiency in the whole
  national economy (and national security) depend
  on efficient and evolving telecom infrastructure
• Low cost for economic competitiveness
• Continually creating new types of services
• New telecom services often enable whole new
  nontelecom business models, e.g. eBay, Amazon

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Options for Increasing Intensity of Spectrum Use

• Use higher spectrum
• Increase modulation/coding efficiency
• Increase frequency reuse
• Antenna issues
• MIMO
• csc2 antennas
• Wireless infrastructure vice antennas
• Use white space

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Cosecant2 Antennas

• Transmitters dont use much spectrum, receivers
  do -- Contains some truth
• Field strength or pfd greater than minimum needed
  has an impact on receivers of other systems
• Selectivity limits
• Desensitization
• Receiver generated 3rd order intermodulation

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Cosecant2 Antennas

• Developed in WWII for uniform radar
  illuminination, but now practical for comm
• Real comm systems are limited by adjacent band
  signals and receiver limitations
• Efficiency can be improved by making ground
  illumination more uniform
• Was major factor in Nextel problem

http//www.optimalrf.com/pdfs/AMH1000.pdf
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White SpaceThe Inevitable Consequence of
Traditional Spectrum Policies

• Traditional spectrum policies assign spectrum
  based on peak demand
• Uneven spatial density of demand another factor
• Newer industries at a disadvantage

Only major US city with major urban military base
Note reliable measurements are very difficult to
make
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Even at Times of Urgent Spectrum Need There is
White Space!
Observations in New York City during 2004
Republican Convention http//www.sharedspectrum.co
m/?sectionmeasurements
Heavily used band
Lightly used band
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White Space

• Exists in large amounts even in major urban areas
• Results from
• Uneven spatial demand for spectrum
• Terrain signal blockage
• Assigning spectrum for peak demand
• Users with high peak/average ratio
• Spectrum hoarding/Nonenforcement of diligence
  requirements

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Public Safety White Space Observations
Police spectrum use in NY state
Peak
Average
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A Definition of Cognitive Radio

• A radio that makes decisions on parameters like
  frequency, power, modulation etc. based on some
  or all of the following
• Location information
• Location dependent rules
• Time of day
• Observed spectrum use
• Negotiations/interactions with other users
• Avoiding interference to allow use of modest cost
  analog amplifiers and front ends

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DARPA xG Programhttp//www.daml.org/meetings/2005
/04/pi/DARPA_XG.pdf
An example of military RD on cognitive radio
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Using CR Technology in White Space

• I. Real Time Spectrum Markets
• Leasing of spectrum on a real time/near real time
  basis using a market-based system
• Modeled after electric utility real time trading
  of bulk power
• II. Interruptible Spectrum
• Leasing of public sector spectrum to other
  users at times of low demand - subject to rapid
  reliable reversion
• Modeled after electric utility load
  management/interruptible electricity practice
• Both are based on voluntary interactions between
  licensees/assignees and potential users
• III. Nonconsensual use - Not discussed today
• See Docket 04-186

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Pragmatism

• Pragmatically, these options get the efficiency
  benefits of cognitive radio without the
  confrontation/opposition associated with
  nonconsensual opportunistic use
• More likely to get fielded in near term than
  nonconsensual

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But Isnt This Unjust Enrichment?

• Some might call allowing licensees of lightly
  used spectrum to profit from it unjust
  enrichment
• But,
• Pragmatically governments can not recover lightly
  used spectrum without lengthly proceedings
• Public sector users really do need peak capacity
• Better to go with the flow

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Real Time Spectrum Markets

• FCC already permits secondary markets in
  spectrum for most licensees
• Other countries are considering comparable
  policies - spectrum trading
• Oddly, recent FCC rules appear to put a 24 hour
  delay on effect of leases
• Not explained in RO
• Work around appears to exist

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Exchange Mechanisms Facilitate Markets

• Oil, pork bellies, electric power,etc can be
  bought and sold readily because well defined
  exchange mechanisms exist and commodity is well
  defined
• Real time spectrum markets also need such
  mechanisms and definitions

Exchange Mechanism
Information about Spectrum availability
Information about Spectrum availability
Bids
Bids
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Interruptible Concept
Full Time Public Sector Block Meets
requirements 99 of time 30 Channels
Full Time Commercial Block 30 Channels
Commercial Block Subject To Interruption By
Public Sector User 60 Channels

• Suggest grouping commercial blocks, public
  sector blocks and an interruptible block
• Public sector state local public safety,
  federal civil and military use

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Who Would Want to Use Interruptible Spectrum?

• Thoughtful public sector users who are willing
  to share spectrum at time of low demand in
  exchange for income and want surge capacity for
  crises
• Wireless providers who understand they can
  acquire spectrum at low cost and use it for
  services that can tolerate time varying capacity,
  e.g. SMS, Blackberry
• Using combination of both interruptible and
  normal spectrum lowers time variability

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Interruptible in Action
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Simulation of Interruptible Spectrum
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Interruptible Implementation

• Interrupt mechanism must be both credible and
  ultrareliable
• Several options available
• Beacon enabling for positive control looks most
  promising compromise

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Regulation Interruptible Spectrum

• FCC has considered but is going slow
• Recently allowed leasing of spectrum among public
  safety users
• NTIA/IRAC has shown zero interest to date

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Cognitive Radio Summary

• Real time spectrum markets and interruptible
  spectrum may achieve spectrum intensity benefits
  of cognitive radio in the near term without the
  confrontations and regulatory difficulties
  intrinsic to nonconsensual sharing

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UCSD Symposium on Spectrally Efficient Wireless
CommunicationsThe Technology and Politics of
Increasing Intensity of Spectrum Use
Consulting on wireless technology and policy
Thanks for Listening
Questions?

• Michael J. Marcus, Sc.D., FIEEE
• Director
• Marcus Spectrum Solutions, Paris, France
• mjmarcus_at_alum.mit.edu
• www.marcus-spectrum.com