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The Significance of TV White Spaces
The document discusses the significance of TV white spaces (TVWS) in providing license-exempt access to unused spectrum, highlighting potential challenges like legal issues and restrictive requirements. It presents a vision for enhanced spectrum access between 3 GHz and 9 GHz, emphasizing the utility of higher frequencies. Additionally, it addresses misconceptions about TV spectrum and explores technologies like MIMO and beamforming for improved wireless communication efficiency.
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The Significance of TV White Spaces
- 1. Significance of TV White Spaces Brough Turner netBlazr brough@netblazr.com
- 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. Long term significance • License-‐exempt access to otherwise unused spectrum, on a secondary use basis, despite powerful vested interests 4 October 2010 3
- 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. Spectrum Myths TV Spectrum is “beach front” spectrum 5
- 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. Higher frequency • Tighter Fresnel zone • Less clearance required 4 October 2010 7
- 8. Noise 4 October 2010 8
- 9. Free space path loss 9
- 10. Free space path loss Seems to say more , more loss 10
- 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. 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. Refrac@on and reflec@ons Shorter wavelength -‐ more reflec@ons, refrac@on “Mul@Path” “Ghosts” if a single receiver 13
- 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. Beamforming ~2014: >300 Mbps Wi-‐Fi to ~1 Km at mass market prices … 4x4 MIMO with 8 antenna elements 15
- 16. Beamforming ~2014: >300 Mbps Wi-‐Fi to ~1 Km at mass market prices … 4x4 MIMO with 8 antenna elements 16
- 17. Beamforming ~2014: >300 Mbps Wi-‐Fi to ~1 Km at mass market prices … 4x4 MIMO with 8 antenna elements 17
- 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. Thank You Brough Turner brough@netblazr.com