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The Significance of TV White Spaces

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Although I have high hopes for TVWS I also expect that, 10-20 years from now, we will look back on the TV White Spaces decision and recognize it as a breakthough in getting access to all otherwise unused spectrum, for example in the 3 GHz - 9 GHz range.

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The Significance of TV White Spaces

  1. 1. Significance     of  TV  White   Spaces   Brough  Turner   netBlazr   brough@netblazr.com  
  2. 2. Disclaimer   •  I  look  forward  to  great  things  from  TVWS   •  I  am  worried  adop@on  will  be  slowed  by:   –  Law  suits   –  Restric@ve  requirements  for  an  antenna’s   Height  Above  Average  Terrain  (HAAT)   –  Adjacent  channel  restric@ons  limit  urban  use   and  limit  the  poten@al  market  size   •  But  Carl  invites  me  because  I’m  disrup@ve!   4  October  2010   2  
  3. 3. Long  term  significance   •  License-­‐exempt  access  to  otherwise   unused  spectrum,  on  a  secondary  use   basis,  despite  powerful  vested  interests   4  October  2010   3  
  4. 4. Long  term  significance   •  License-­‐exempt  access  to  otherwise   unused  spectrum,  on  a  secondary  use   basis,  despite  powerful  vested  interests   •  20  year  dream:    similar  access  to  unused   spectrum  between  3  GHz  and  9  GHz   •  Why?    Higher  spectrum  more  useful  !   4  October  2010   4  
  5. 5. Spectrum  Myths          TV  Spectrum  is  “beach  front”  spectrum   5  
  6. 6. Spectrum  Myths          TV  Spectrum  is  “beach  front”  spectrum   •  Based  on  20th  century  technology,  not  physics!   –  Travels  farther  thru  the  air  –  No!   –  Thru  windows  –  roughly  the  same   –  Goes  thru  masonry  –  yes,  with  50,000  waas!   6  
  7. 7. Higher  frequency   •  Tighter  Fresnel  zone   •  Less  clearance  required   4  October  2010   7  
  8. 8. Noise   4  October  2010   8  
  9. 9. Free  space  path  loss   9  
  10. 10. Free  space  path  loss   Seems  to  say  more    ,  more  loss   10  
  11. 11. Free  space  path  loss   Seems  to  say  more    ,  more  loss   But  this  equa@on  encapsulates  two  effects:     Actual  path  loss  (independent  of  frequency!  )     Receiving  antenna  aperture  (assumed  to  be  ½  wavelength)   11  
  12. 12. Free  space  path  loss   Seems  to  say  more    ,  more  loss   But  this  equa@on  encapsulates  two  effects:     Actual  path  loss  (independent  of  frequency!  )     Receiving  antenna  aperture  (assumed  to  be  ½  wavelength)   5  GHz  photons  go  just  as  far  as  50-­‐700  MHz  photons  !   12  
  13. 13. Refrac@on  and  reflec@ons   Shorter  wavelength  -­‐  more  reflec@ons,  refrac@on     “Mul@Path”    “Ghosts”  if  a  single  receiver   13  
  14. 14. MIMO:  Mul@ple  Input  Mul@ple  Output   •  Mul@ple  paths  improve  link  reliability  and  increase   spectral  efficiency  (bps/Hz),  range  &  direc@onality   14  
  15. 15. Beamforming   ~2014:    >300  Mbps  Wi-­‐Fi  to  ~1  Km        at  mass  market  prices  …   4x4  MIMO   with  8     antenna     elements   15  
  16. 16. Beamforming   ~2014:    >300  Mbps  Wi-­‐Fi  to  ~1  Km        at  mass  market  prices  …   4x4  MIMO   with  8     antenna     elements   16  
  17. 17. Beamforming   ~2014:    >300  Mbps  Wi-­‐Fi  to  ~1  Km        at  mass  market  prices  …   4x4  MIMO   with  8     antenna     elements   17  
  18. 18. MIMO  &  Beamforming   •  Ideal  antenna  element     separa@on  >=  ½  wavelength   –  2.1  meters  at  70  MHz   –  21  cm  at  700  MHz   •  But  only   –  2.5  cm  for  5.8  GHz  Wi-­‐Fi   Ruckus  Wireless   Wavion  Networks   D-­‐Link  DAP-­‐2553   18  
  19. 19. Thank  You   Brough  Turner   brough@netblazr.com  

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