Wireless Optical Networking: An Overview

Wireless Optical Networking: An Overview Tim Miller Product Manager Broadband Wireless World Forum 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)

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

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

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

Free-space Loss Signal power loss due to light beam divergence in free space • 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 Pointsource emitter Photodiode Only a portion of the emitting power is captured by the receiver due to geometric spreading losses

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 • OptiMesh Features: • < 500m links • Power Control • Automatic Tracking • Mesh Network

Atmospheric Attenuation Effects(Tokyo) Very Heavy Rain Conditions Attenuation (dB/km) Tokyo 7-21-1999 Time

Clear, good visibility Heavy rain Benchmark Visibility Data(Tokyo)

Atmospheric Attenuation Effects(Montgomery Field) Fog Conditions Attenuation (dB/km) Time

Clear, good visibility Heavy fog visibility Benchmark Visibility Data(Montgomery Field) Laser retro-reflection

Atmospheric Attenuation Effects(Ottawa) Snow Conditions Attenuation (dB/km) Time

Clear, good visibility Snow Benchmark Visibility Data(Ottawa)

Scintillation The variation of refractive index along the propagation path caused by slight temperature variations among different air pockets Amplitude fluctuation Image dancing • 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

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

Network Topology = Reliability (Point to Point) D 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 A 150m, 100% B 200m, 99.999% 300m, 99.99% C San Francisco Availability A: 100% 0 min B: 99.999% 5 min C: 99.99% 52 min D: 99.9% 525 min Addressable market

Wireless Optical Networking • AirFiber’s OptiMesh: • Automatic Acquisition – easy installation • Automatic Tracking – always optimized • Mesh Network – ultimate protection scheme • Element Management System – carrier class

Network Topology = Reliability (Mesh) To alternate POP D 250m, alternate path A • 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% 150m, 100% 200m, 99.999% B 125m, 100% C Availability A: 100% 0 min B: 100% 0 min C: 100% 0 min D: 99.999% 5 min San Francisco Addressable market

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

Network Architecture

Planning a Wireless Optical Network

Fiber Microwave Link Optical Link Microwave Backhaul, OptiMesh Access • 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.

Fiber Microwave Link Optical Link Optical with Microwave Backup • 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.

Mesh Extension • 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. OptiMesh Node Microwave Node Fiber POP 3.

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

Wireless Optical Networking: An Overview