Download fso-onr - Shivkumar Kalyanaraman

Ultra-High-Speed Wireless Ad-Hoc Networks using
Free-Space-Optics (FSO)
Shiv Kalyanaraman, Murat Yuksel, Partha Dutta
[email protected]
: “shiv rpi”
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Motivations: Free-Space-Optical (FSO) AdHoc Networks: Mobile or Fixed Multi-Hop
Application: Mixed RF/FSO Ad-Hoc Networks
(Military Application)
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Bringing Optical Communications and Ad Hoc
Networking Together…
Free-Space-Optical
Communications (FSO)
Ad Hoc
Networking
High bandwidth
Low power
Directional
Mobile communication
Auto-configuration
Free-Space-Optical
Ad Hoc Networks
Spatial reuse and angular diversity in nodes
Low power and secure
Electronic auto-alignment
Optical auto-configuration (switching, routing)
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Current Commercial FSO
Point-to-Point Links in dense metros, competing with “wires”
and “leased lines”
Issue: How to achieve link reliability/availability despite weather
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Ad-Hoc/Meshed Optical Wireless:
Why?

Positive points:





High-brightness LEDs (HBLEDs) are very low cost and highly reliable
components
 35-65 cents a piece, and $2-$5 per transreceiver package + upto 10 years
lifetime
Very low power consumption (100 microwatts for 10-100 Mbps!)
 Even lower power for 1-10 Mbps
 4-5 orders of magnitude improvement in energy/bit compared to RF
Directional => Huge spatial reuse => multiple parallel channels for huge
bandwidth increases due to spectral efficiency
More Secure: Highly directional + small size & weight => low probability of
interception (LPI)
Issues:


Need line-of-sight (LOS); and alignment of LOS & network auto-configuration
Need to deal with weather & temporary obstacles, alignment loss
Challenge: leverage huge benefits while tackling problems.
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Optical Wireless: Commodity
components
LEDs…
VCSELs…
IrDAs…
Lasers…
Many FSO components are very low cost and available
for mass production.
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Spatial Re-use: 2D FSO Arrays: 1-100Gbps
Backhaul
Node 1
Node 2
D
D/N
…
Node 1
Repeater 2
Repeater 1

Node 2
Repeater N-1
1cm2 LED/PIN => 1000 pairs in 1ft x 1ft square structure
 100 Gbps aggregate bandwidth (= 1000 x 100 Mbps)
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Aggregate Capacity in 2-d Arrays:
Interference vs Density vs Distance
Interference Error vs.
Packaging Density
Bandwidth-Volume Product
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Auto-Alignment: 3D Spherical FSO
Structures
LED
Micro Mirror
PhotoDetector
Spherical Antenna
Cluster of FSO Components Optical Transmitter/Receiver Unit
LOS
Step1: LOS Detection Through the use of Spherical FSO Antenna Array
Step2: Links Set-Up by Bundling LOS’ through Mirror adjustments for each LED-Photodetector Units
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Initial Ad-Hoc FSO Prototypes
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Initial Ad-Hoc FSO Prototypes (contd)
60
50
Misaligned
Aligned
40
Duration of Alignment (%)
30
20
10
100
128
121
112
105
97.5
88.5
79
72
65
51.5
40.5
33
23
17
11
0
0
Light Intensity (lux)
Received Light Intensity
from the moving
train.
70
50
Angular Position of the Train (degree)
Very dense packaging
and high mobility are
feasible.
0
0
0
20
10
40
20
60
30
80
40
100
50
120
Circuit Delay (milliseconds)
Shivkumar Kalyanaraman
Angular Speed (degrees/second)
Rensselaer Polytechnic Institute
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Initial FSO Prototypes
Inside of the sphere
is coated w/ mirror
Photo-detector
Integrating ball to increase
angle of reception – inside is
coated with mirror.
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Audio Transmission on FSO Link using low cost
LED’s and Photo Diodes: Two Channel Mixing
a) Two transmitters on different
channels
Rensselaer Polytechnic Institute
b) Single receiver and circuit for both
the channels
Indoor FSO ad-hoc networks Shivkumar Kalyanaraman
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Indoor Ad-Hoc FSO: Music App (contd)
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Hybrids: 3D Auto-Alignment with 2D Arrays
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Auto-configuration: Location tracking and
management

Location tracking: (optional integration w/ GPS)
Use highly granular spherical FSO antennas (e.g. hundreds of
transceivers)  can detect angle of arrival
 Use time of flight or signal strength  can detect distance
 Unlike RF, no need for triangulation: sense of direction is available.
Allows easy integration with Community Wireless Networks (CWNs)
 Organic network growth


 - angle of arrival
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Emerging Apps: Broadband Sensor Networks:
Eg: Mobile/Fixed Camera Networks


More than 10,000
public and private
cameras in
Manhattan, 2.5
million in the UK!
Subways, airports,
battlefields,
factory floors,
highways…

Thousands of un-supervised and moving cameras w/o centralized
processing or control
 Key: Mix of Low Power AND High Speed AND Ad-Hoc/Unsupervised
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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SUMMARY: Ultra-Broadband
Wireless: puzzle falling in place…

(1) Infinite Spectrum in Thin Air!
 Key: use unlicensed spectrum or larger licensed bands

(2) Multi-hop architecture w/ Base-Station Interfaces
 Wireless is fundamentally cheap for shorter distances, smaller coverage
 Organic architecture: auto-conf, self-management (10+ years of research in ad-hoc
networks), community wireless
 IP/geographic routing, fully distributed traffic engineering mechanisms
 Technology neutral, extensible, modular: 802.11x, 802.16x, FSO
 (2a) Multi-hop Free-space-optics (FSO) using ultra-low-cost components for
100 Gbps+ capabilities

Key: Broadband CWNs & ad-hoc FSO complementary to ongoing advances in
FTTH, DSL/Cable, WiMax, 3G rollouts.
 Open Problems in upgrading the network and transport layers to leverage raw, but
distributed bandwidth, and tolerate higher bursty losses (weather related)
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Thanks!
Student Heroes:
Jayasri Akella, [email protected]
Dr. Murat Yuksel (post-doc): [email protected]
Chang Liu, [email protected]
David Partyka, [email protected]
Sujatha Sridharan
Bow-Nan Cheng: [email protected] (CWN project)
: “shiv rpi”
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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