1. Wireless Optical Networking: An Overview Tim Miller Product Manager Broadband Wireless World ForumFebruary 19, 2001

2. February 19, 2001 AirFiber Overview  Telecommunications equipment supplier of wireless optical mesh networks to carriers worldwide  San Diego, California  Founded in 1998  Investors: –Enterprise Partners –Foundation Capital –Nortel Networks –Qualcomm  Strategic Partners –Nortel Networks (OEM, OPTera Metro 2400)

3. February 19, 2001 Agenda  Introduction  Overview of free-space optics (FSO) and wireless optical networks (WON) –FSO – As it was Obstacles to deployment Affects of weather –FSO – As it is Technology improvements Network topologies – FSO vs. WON  Planning a WON  Integrating WON and Microwave Systems

4. February 19, 2001 Free-Space Optics – Technical Challenges  Free-Space Optics – an experienced technology  Misapplied in early implementations  Four leading obstacles of free-space laser transmission –Free-space loss –Attenuation –Mie scattering - Fog –Scintillation

5. February 19, 2001 Last Mile(s) Access – As It Was Fiber Optic SONET/SDH Ring ATM Switch ADM OC12c /STM4 Fiber Distribution NOC ADM OC12c /STM4 NTU Router LAN WEB Premise Network Access Network Core Network Fiber Microwave Copper

6. February 19, 2001 Free-space Loss  Possible solutions –Increase power – marginal gain, lowers MTBF, not optimized –Increase # beams – expensive, still not optimized –Focus beam and auto track – cost effective, always optimized Signal power loss due to light beam divergence in free space Point source emitter Photodiode Only a portion of the emitting power is captured by the receiver due to geometric spreading losses

7. February 19, 2001 OptiMesh Features: < 500m links Power Control Automatic Tracking Mesh Network Typical Weather Attenuation  Clear Conditions: -5 to -15 dB/km  Rain: -20 to -50 dB/km  Snow: -50 to -150 dB/km  Fog: -50 to -300 dB/km

8. February 19, 2001 Attenuation (dB/km) Time Atmospheric Attenuation Effects (Tokyo) Very Heavy Rain Conditions Tokyo 7-21-1999

9. February 19, 2001 Benchmark Visibility Data (Tokyo)  Clear, good visibility  Heavy rain

10. February 19, 2001 Attenuation (dB/km) Time Atmospheric Attenuation Effects (Montgomery Field) Fog Conditions

11. February 19, 2001 Benchmark Visibility Data (Montgomery Field)  Clear, good visibility  Heavy fog visibility Laser retro-reflection

12. February 19, 2001 Attenuation (dB/km) Atmospheric Attenuation Effects (Ottawa) Snow Conditions Time

13. February 19, 2001 Benchmark Visibility Data (Ottawa)  Clear, good visibility  Snow

14. February 19, 2001 Solution: - Scintillation is not significant for links less than 500 m; but effects increase rapidly with longer distances - Avoid links over/through vents, hot roofs, A/C ducts, etc - Space diversity Scintillation Image dancing Amplitude fluctuation The variation of refractive index along the propagation path caused by slight temperature variations among different air pockets

15. February 19, 2001 Free Space Optics – As It Is Today  Demographics have changed –Internet has created bandwidth explosion in urban areas –Fiber access – only 5% commercial buildings  Technology has improved –Reliability, eye safety, network management  Maintains price performance lead – bandwidth / $ A reliable, affordable and quickly deployable way to extend fiber’s reach in access network

16. February 19, 2001 D 150m, 100% 200m, 99.999% A C B 300m, 99.99% 400m, 99.9% Building with Point to Point Reliability decreases with expansion Available market limited - Reliability - LOS Roof costs increase No alternate route No flexibility Availability A: 100%0 min B: 99.999%5 min C: 99.99%52 min D: 99.9%525 min San Francisco Network Topology = Reliability (Point to Point) Addressable market

17. February 19, 2001 Wireless Optical Networking  AirFiber’s OptiMesh: –Automatic Acquisition – easy installation –Automatic Tracking – always optimized –Mesh Network – ultimate protection scheme –Element Management System – carrier class

18. February 19, 2001 D 150m, 100% A C B Migrating to a Mesh: Reliability increases with expansion - Shorter links - Path protection - Equipment Available market increases: - Reliability - LOS Roof costs decrease Many alternate routes Flexible 100m, 100% 200m, 99.999% 125m, 100% To alternate POP 250m, alternate path Availability A: 100%0 min B: 100%0 min C: 100%0 min D: 99.999%5 min Addressable market Network Topology = Reliability (Mesh) San Francisco

19. February 19, 2001 Availability - Achieving 99.999%  Tree -> Mesh Network –Shorter links –Multiple redundant paths into each building –Automatic re-routing of circuits  Node Equipment –8-year Mean-Time-Between-Failure (MTBF) –Single unit to replace in case of failure –No scheduled maintenance  Automatic tracking –Continuous optimization of the link alignment –Adjusts for building movement from solar and wind load

20. February 19, 2001 Network Architecture

21. February 19, 2001 Planning a Wireless Optical Network

22. February 19, 2001 Planning a Wireless Optical Network

23. February 19, 2001 Planning a Wireless Optical Network

24. February 19, 2001 Microwave Backhaul, OptiMesh Access Fiber Microwave Link Optical Link Microwave provides backhaul; Optical provides access Benefits: Increased capacity on backhaul links – Higher ROI Preserves frequency spectrum for short hops Lowers deployment costs Minimizes aesthetic problems 1.

25. February 19, 2001 Optical with Microwave Backup Fiber Microwave Link Optical Link Optical link at clear air distance with RF backup Benefits: Higher speed Extends reach of optics. Achieves 99.999% availability with backup Provides migration path to mesh network / redeployment Less expensive than fully redundant radio Provides for load balancing without using more spectrum 2.

26. February 19, 2001 Mesh Extension OptiMesh Node Microwave Node Fiber POP Microwave system provides alternate path to reroute between locations Microwave is part of mesh Media is transparent to network. Allows for fully integrated, end to end network. 3.

27. February 19, 2001 Summary  Wireless Optical Networks – Ready for Prime Time –Fiber capacity without the costs –Demographics – short links –Automatic tracking –Highest performance (bandwidth/$)  Network Topology = Increased Reliability –Grow network into a mesh topology  Complementary with other technologies….not a replacement