Post on 05-Jan-2016
description
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Ultra-High-Speed Wireless Ad-Hoc Networks using Free-Space-Optics (FSO)
Shiv Kalyanaraman, Murat Yuksel, Partha Dutta
shivkuma@ecse.rpi.edu
: “shiv rpi”
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Motivations: Free-Space-Optical (FSO) Ad-Hoc Networks: Mobile or Fixed Multi-Hop
Application: Mixed RF/FSO Ad-Hoc Networks (Military Application)
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Bringing Optical Communications and Ad Hoc Networking Together…
Mobile communicationAuto-configuration
Free-Space-Optical Communications (FSO)
Ad Hoc Networking
Free-Space-Optical Ad Hoc Networks
Spatial reuse and angular diversity in nodesLow power and secureElectronic auto-alignmentOptical auto-configuration (switching, routing)
High bandwidthLow powerDirectional
Shivkumar KalyanaramanRensselaer 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 KalyanaramanRensselaer 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 KalyanaramanRensselaer Polytechnic Institute
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Optical Wireless: Commodity components
Many FSO components are very low cost and available for mass production.
Lasers…
LEDs…
VCSELs…
IrDAs…
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Spatial Re-use: 2D FSO Arrays: 1-100Gbps Backhaul
1cm2 LED/PIN => 1000 pairs in 1ft x 1ft square structure 100 Gbps aggregate bandwidth (= 1000 x 100 Mbps)
Node 1 Node 2
…Node 1 Node 2
Repeater 1 Repeater 2 Repeater N-1
DD/N
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Aggregate Capacity in 2-d Arrays: Interference vs Density vs Distance
Bandwidth-Volume Product
Interference Error vs. Packaging Density
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Auto-Alignment: 3D Spherical FSO Structures
LED
PhotoDetector
Micro Mirror
Spherical Antenna Cluster of FSO Components Optical Transmitter/Receiver Unit
Step2: Links Set-Up by Bundling LOS’ through Mirror adjustments for each LED-Photodetector Units
Step1: LOS Detection Through the use of Spherical FSO Antenna Array
LOS
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Initial Ad-Hoc FSO Prototypes
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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0
20
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60
80
100
120
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10
20
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40
50
0
50
100
Circuit Delay (milliseconds)
Duration of Alignment (%)
Angular Speed (degrees/second)
0
10
20
30
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60
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0
11
17
23
33
40
.5
51
.5 65
72
79
88
.5
97
.5
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2
12
1
12
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Angular Position of the Train (degree)
Lig
ht
Inte
ns
ity
(lu
x)
Initial Ad-Hoc FSO Prototypes (contd)
Very dense packaging and high mobility are
feasible.
Misaligned Aligned
Received Light Intensity from the moving
train.
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Initial FSO Prototypes
Integrating ball to increase angle of
reception – inside is coated with mirror.
Inside of the sphere is coated
w/ mirror
Photo-detector
Shivkumar KalyanaramanRensselaer 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
b) Single receiver and circuit for both the channels
Indoor FSO ad-hoc networks
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Indoor Ad-Hoc FSO: Music App (contd)
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Hybrids: 3D Auto-Alignment with 2D Arrays
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Time o
f flig
ht
- angle of arrival
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
Shivkumar KalyanaramanRensselaer Polytechnic Institute
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Emerging Apps: Broadband Sensor Networks:
Eg: Mobile/Fixed Camera Networks
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
More than 10,000 public and private cameras in Manhattan, 2.5 million in the UK!
Subways, airports, battlefields, factory floors, highways…
Shivkumar KalyanaramanRensselaer 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 KalyanaramanRensselaer Polytechnic Institute
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Thanks!
: “shiv rpi”
Student Heroes: Jayasri Akella, sri@networks.ecse.rpi.eduDr. Murat Yuksel (post-doc): yuksem@ecse.rpi.eduChang Liu, c.liu@ee.unimelb.edu.auDavid Partyka, partyd@rpi.eduSujatha SridharanBow-Nan Cheng: chengb@rpi.edu (CWN project)