Wireless Optical Networking: An Overview

Tim Miller

Product Manager

Broadband Wireless World Forum February 19, 2001

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)

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

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

February 19, 2001

Last Mile(s) Access – As It Was

Fiber OpticSONET/SDH Ring

ATMSwitch

ADM

ADM

ADMOC12c /STM4

FiberDistribution

NOC

ADMOC12c /STM4

NTU

Router

LAN

WEB

Premise NetworkAccess NetworkCore Network

Fiber

MicrowaveCopper

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

Pointsourceemitter

Photodiode

Only a portion of the emitting power is captured by the receiver due to geometric

spreading losses

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

February 19, 2001

Att

enu

atio

n (

dB

/km

)

Time

Atmospheric Attenuation Effects(Tokyo)

7-21 KDI 1

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

5:39

:31

6:18

:56

6:58

:06

7:36

:16

8:14

:25

8:52

:36

9:31

:07

10:0

9:56

10:4

9:34

11:2

7:08

12:0

5:20

12:4

2:32

13:2

1:02

13:5

9:12

14:3

7:23

15:1

4:38

15:5

4:11

16:2

8:24

17:0

4:47

17:4

0:16

18:1

7:34

18:5

4:01

19:3

2:12

20:1

0:19

20:4

8:24

21:2

7:35

22:0

5:47

22:4

3:10

23:2

1:19

0:00

:26

0:38

:34

1:15

:44

1:54

:13

2:31

:26

3:10

:34

3:48

:46

4:26

:13

5:04

:22

Very Heavy Rain Conditions

Tokyo7-21-1999

February 19, 2001

Benchmark Visibility Data(Tokyo)

Clear, good visibility Heavy rain

February 19, 2001

Att

enu

atio

n (

dB

/km

)

Time

Atmospheric Attenuation Effects(Montgomery Field)

Fog Conditions

4-15-99 Montgomery

-250

-200

-150

-100

-50

0

50

0:00:00 4:48:00 9:36:00 14:24:00 19:12:00 0:00:00 4:48:00

February 19, 2001

Benchmark Visibility Data(Montgomery Field)

Clear, good visibility Heavy fog visibility

Laser retro-reflection

February 19, 2001

Att

enu

atio

n (

dB

/km

)

Atmospheric Attenuation Effects(Ottawa)

Snow Conditions

Time

February 19, 2001

Benchmark Visibility Data(Ottawa)

Clear, good visibility Snow

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 dancingImage dancing

Amplitude fluctuation

Amplitude fluctuation

The variation of refractive index along the propagation path caused by slight temperature variations among different air pockets

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

February 19, 2001

POP

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

AvailabilityA: 100% 0 minB: 99.999% 5 minC: 99.99% 52 minD: 99.9% 525 min

San Francisco

Network Topology = Reliability (Point to Point)

Addressable market

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

February 19, 2001

POP

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

AvailabilityA: 100% 0 minB: 100% 0 minC: 100% 0 minD: 99.999% 5 min

Addressable market

Network Topology = Reliability (Mesh)

San Francisco

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

February 19, 2001

Network Architecture

February 19, 2001

Planning a Wireless Optical Network

February 19, 2001

Planning a Wireless Optical Network

February 19, 2001

Planning a Wireless Optical Network

February 19, 2001

Microwave Backhaul, OptiMesh Access

Fiber Microwave LinkOptical Link

Microwave provides backhaul;Optical provides access

Benefits:

• Increased capacity onbackhaul links – Higher ROI

• Preserves frequency spectrum for short hops

• Lowers deployment costs

• Minimizes aesthetic problems

1.

February 19, 2001

Optical with Microwave Backup

Fiber Microwave LinkOptical 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.

February 19, 2001

Mesh Extension

OptiMesh NodeMicrowave NodeFiber 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.

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