Crsm 8 2009 John Chapin Mit Cognitive Use Of Tv White Space

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Crsm 8 2009 John Chapin Mit Cognitive Use Of Tv White Space

  1. 1. Version 3: 10 May 2009 Cognitive Use of TV Whitespace Regulatory and Market Implications John Chapin William Lehr MIT RLE MIT CSAIL jchapin@mit.edu wlehr@mit.edu First IBBT-MIT Joint Workshop on Cognitive Radio Standardization and Markets 11 May 2009 Claude E. Shannon Communication and Network Group Communications Futures Program Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology
  2. 2. Outline TV whitespace in the USA Policy analysis of the TVBD approach Technical and market analysis Copyright © 2009 John Chapin and William Lehr, MIT 2
  3. 3. What / Where are the TV White Spaces? VHF & Lower UHF Bands More (> 70 MHz) in smaller markets Not much in urban markets New Orleans San Francisco Washington DC Minneapolis St Louis Boston Copyright © 2009 John Chapin and William Lehr, MIT Slide by: Peter Tenhula, SDRF 3
  4. 4. FCC proposal: unlicensed secondary access to TV spectrum Primary users in the US –  High-power television –  Low-power television repeaters, relays –  Public safety land-mobile radio channels 14-20 in some big cities –  Wireless microphones only 1 out of 400 are legal users Cognitive radio methods to protect primary users –  Secondary user determines own location –  Query central database to determine potentially available channels –  Listen for primary users in specific channel Secondary device requirements –  Check central database every day –  Detect primary users at -114 dBm •  approximately -15 dB signal to noise ratio –  Max transmit power 4 W if fixed, 100 mW if portable Copyright © 2009 John Chapin and William Lehr, MIT 4
  5. 5. TV whitespace status in the USA Rules adopted November 2008, published February 2009 Unknown when the rules will take effect, if at all –  17 petitions for reconsideration –  3 lawsuits •  National Association of Broadcasters •  Association for Maximum Service Television •  Coaltion of wireless microphone users (ESPN, sports leagues, theaters) –  New Obama government with new priorities In this talk, “TVBD” means the FCC’s current proposal Copyright © 2009 John Chapin and William Lehr, MIT 5
  6. 6. Outline TV whitespace in the USA Policy analysis of the TVBD approach Technical and market analysis Copyright © 2009 John Chapin and William Lehr, MIT 6
  7. 7. Potential goals for TV whitespace policy Maximize productive use of spectrum –  Technical efficiency amount of data transmitted –  Economic benefit value of economic surplus generated –  Social value number of people served or needs met Provide low-cost spectrum access –  Promote services for underserved populations –  Promote innovative business models –  Enhance competition for existing services Establish viability of cognitive radio for spectrum sharing –  Make it easier to share other bands in the future Copyright © 2009 John Chapin and William Lehr, MIT 7
  8. 8. Goal: Maximize productive use of TV broadcast spectrum TVBD proposal is one approach... –  TVBD = non-cooperative unlicensed secondary use of TV spectrum ... out of many possible policy options –  Market-oriented mechanisms –  Non-market mechanisms Cognitive Radio can be used to support any of the policy options Copyright © 2009 John Chapin and William Lehr, MIT 8
  9. 9. Market-oriented mechanisms Make licenses more technically and service neutral Establish property rights –  Coasian: allow compensation for interference –  Secondary market for transmission licenses Example: Qualcomm MediaFLO in UHF chan 55 (716-722 MHz) Cognitive radio can support these market mechanisms –  When deploying new systems, use CR to avoid interference –  Cooperative secondary use •  Contract between licensee and secondary users •  CR enables licensee to retain some transmission rights •  e.g. CPC broadcasts availability, terms and conditions Copyright © 2009 John Chapin and William Lehr, MIT 9
  10. 10. Non-market mechanisms Regulator allows unlicensed secondary use –  “TVBD” approach –  Non-cooperative: existing licensees do not have control Regulator reallocates existing licenses –  FCC reserved some UHF channels for for public safety broadband Regulator allocates new secondary use licenses –  TVBD proposal reserves 2 channels nationwide for wireless microphones –  De facto this is a license for (currently illegal) wireless microphone users Cognitive Radio can support these non-market mechanisms –  Eg. use CR to avoid interference during reallocation transition Copyright © 2009 John Chapin and William Lehr, MIT 10
  11. 11. Evaluation of TVBD approach against policy goals Maximize productive use of spectrum –  Much more spectrum usage than current situation –  Likely less efficient than fully liberalized market –  Possible tragedy of the anticommons •  Many unlicensed users make it difficult to reallocate band in the future Provide low-cost spectrum access –  Unclear whether services being discussed are viable (next slides) –  Nevertheless, high potential for innovative uses Establish viability of non-cooperative spectrum sharing –  Excellent opportunity to demonstrate success –  Not a good model for some other major sharing opportunities •  Government bands Copyright © 2009 John Chapin and William Lehr, MIT 11
  12. 12. Outline TV whitespace in the USA Policy analysis of the TVBD approach Technical and market analysis Copyright © 2009 John Chapin and William Lehr, MIT 12
  13. 13. Key technical issues for the TVBD approach TV band spectrum has long range propagation –  Unlike 2.4 GHz, 5 GHz, and 60 GHz which are short range –  Possible tragedy of the commons Unlicensed users must coordinate quiet times for sensing Important class of primary users are receive-only (TV receivers) –  Hidden node problem reduces utility of spectrum sensing –  Lack of receiver standards –  Digital television picture quality “cliff” For all of these reasons, spectrum access etiquette for TVBDs is expected to evolve significantly Copyright © 2009 John Chapin and William Lehr, MIT 13
  14. 14. Market analysis All applications: uncertain payoff makes investment challenging –  Regulatory risk –  Potential congestion Low-cost internet access –  Free spectrum & long range reduce infrastructure cost for rural coverage –  Google claims TVwhitespace could increase its profits by 20-30% –  Risk: not enough spectrum available for true broadband in populated areas •  Brown/Sicker DYSPAN 2007 paper: 80 MHz needed Home consumer electronics interconnect –  Must use multiple TV channels to achieve 1 Gbps (uncompressed HD video) –  Risk: Competition from 2.4 GHz 802.11n and 60 GHz unlicensed Niche networks –  Exploit low entry cost to meet specialized needs, e.g. sensor networks –  Risk: High device cost due to low volume outweighs benefits of low entry cost Copyright © 2009 John Chapin and William Lehr, MIT 14
  15. 15. Opinion of the authors With low cost spectrum, innovative applications will develop Spectrum sharing is essential for future growth of radio services TV whitespace is an important first step to establish viability Copyright © 2009 John Chapin and William Lehr, MIT 15
  16. 16. Key takeaway points FCC TVBD is one out of many ways to use CR in the TV band Cognitive Radio techniques can also support market mechanisms for increasing productive use of the spectrum Many technical questions face the TVBD approach Methods for primary user protection will evolve over time Viable applications are unknown Copyright © 2009 John Chapin and William Lehr, MIT 16
  17. 17. Next steps Upcoming SDRF workshop –  June 16, 2009 Dearborn, Michigan, USA “Spectrum Access by TV Band Devices” http://www.sdrforum.org Stay tuned to see what happens to TVBD in the USA –  FCC will respond to petitions for reconsideration –  Then lawsuits will be argued Thank you! –  John Chapin William Lehr jchapin@mit.edu wlehr@mit.edu Copyright © 2009 John Chapin and William Lehr, MIT 17
  18. 18. BACKUP SLIDES Copyright © 2009 John Chapin and William Lehr, MIT 18
  19. 19. Managing certification risk for TV Band Devices Many subsystems must work correctly to protect primary users –  location mechanism (GPS or other) –  sensor receiver –  processing of sensor signals –  network connection to database (including security against attackers) –  device attestation –  processing of database response –  clock Policy implications –  Likelihood of problems in the field •  Cannot afford to test to 100% guarantee level –  Solution: make it easy recall to misbehaving devices FCC: DB can alter available channel list based on make/model Open issue: how to more easily determine source of interference Copyright © 2009 John Chapin and William Lehr, MIT 19

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