Transcript AirFiber 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)
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
Access Network
Core Network
Premise Network
NTU
NOC
ATM
Switch
Fiber
Distribution
ADM
LAN
ADM
ADM
OC12c
/STM4
ADM
OC12c
/STM4
Fiber Optic
SONET/SDH Ring
Router
February 19, 2001
WEB
Free-space Loss
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
 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
February 19, 2001
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
February 19, 2001
February 19, 2001
Time
5:04:22
4:26:13
3:48:46
3:10:34
2:31:26
-45
1:54:13
1:15:44
0:38:34
0:00:26
23:21:19
22:43:10
22:05:47
21:27:35
20:48:24
20:10:19
19:32:12
18:54:01
18:17:34
17:40:16
17:04:47
16:28:24
15:54:11
15:14:38
14:37:23
13:59:12
13:21:02
12:42:32
12:05:20
11:27:08
10:49:34
10:09:56
9:31:07
8:52:36
0
8:14:25
7:36:16
6:58:06
6:18:56
5:39:31
Attenuation (dB/km)
Atmospheric Attenuation Effects
(Tokyo)
7-21 KDI 1
Very Heavy Rain Conditions
-5
-10
-15
-20
-25
-30
-35
-40
Tokyo
7-21-1999
-50
Benchmark Visibility Data
(Tokyo)
 Clear, good visibility
February 19, 2001
 Heavy rain
Atmospheric Attenuation Effects
(Montgomery Field)
50
Fog Conditions
Attenuation (dB/km)
0
-50
-100
-150
-200
4-15-99 Montgomery
-250
0:00:00
4:48:00
9:36:00
Time
February 19, 2001
14:24:00
19:12:00
0:00:00
4:48:00
Benchmark Visibility Data
(Montgomery Field)
 Clear, good visibility
 Heavy fog visibility
Laser retro-reflection
February 19, 2001
Atmospheric Attenuation Effects
(Ottawa)
Attenuation (dB/km)
Snow Conditions
Time
February 19, 2001
Benchmark Visibility Data
(Ottawa)
 Clear, good visibility
February 19, 2001
 Snow
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
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
Network Topology = Reliability (Point to Point)
D
Building with Point to Point
A
• Reliability decreases
with expansion
• Available market limited
- Reliability
- LOS
B
• Roof costs increase
POP
C
• No alternate route
• No flexibility
Availability
Addressable market
February 19, 2001
A: 100%
B: 99.999%
C: 99.99%
D: 99.9%
0 min
5 min
52 min
525 min
San Francisco
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
Network Topology = Reliability (Mesh)
To alternate POP
D
A
Migrating to a Mesh:
• Reliability increases
with expansion
- Shorter links
- Path protection
- Equipment
B
POP
C
• Available market increases:
- Reliability
- LOS
• Roof costs decrease
• Many alternate routes
• Flexible
Availability
Addressable market
February 19, 2001
A: 100%
B: 100%
C: 100%
D: 99.999%
0 min
0 min
0 min
5 min
San Francisco
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
Microwave provides backhaul;
Optical provides access
Benefits:
1.
• Increased capacity on
backhaul links – Higher ROI
• Preserves frequency
spectrum for short hops
• Lowers deployment costs
• Minimizes aesthetic problems
February 19, 2001
Fiber
Microwave Link
Optical Link
Optical with Microwave Backup
Optical link at clear air
distance with RF backup
Benefits:
• Higher speed
2.
• 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
February 19, 2001
Fiber
Microwave Link
Optical Link
Mesh Extension
Microwave system
provides alternate
path to reroute
between locations
• Microwave is part
of mesh
OptiMesh Node
Microwave Node
Fiber POP
• Media is
transparent to
network.
• Allows for fully
integrated, end to
end network.
February 19, 2001
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
February 19, 2001