Ultra-High-Speed Wireless Ad-Hoc Networks using Free-Space-Optics (FSO)

1. Ultra-High-Speed Wireless Ad-Hoc Networks using Free-Space-Optics (FSO) Shiv Kalyanaraman, Murat Yuksel, Partha Dutta shivkuma@ecse.rpi.edu : “shiv rpi”

2. Motivations: Free-Space-Optical (FSO) Ad-Hoc Networks: Mobile or Fixed Multi-Hop Application: Mixed RF/FSO Ad-Hoc Networks (Military Application)

3. 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) Bringing Optical Communications and Ad Hoc Networking Together…

4. 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

5. 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.

6. Optical Wireless: Commodity components LEDs… VCSELs… IrDAs… Lasers… Many FSO components are very low cost and available for mass production.

7. Node 1 Node 2 D D/N … Node 2 Node 1 Repeater 2 Repeater N-1 Repeater 1 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)

8. Aggregate Capacity in 2-d Arrays: Interference vs Density vs Distance Bandwidth-Volume Product Interference Error vs. Packaging Density

9. 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 Auto-Alignment: 3D Spherical FSO Structures

10. Initial Ad-Hoc FSO Prototypes

11. Initial Ad-Hoc FSO Prototypes (contd) Very dense packaging and high mobility are feasible. Received Light Intensity from the moving train. Misaligned Aligned

12. 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.

13. 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

14. Indoor Ad-Hoc FSO: Music App (contd)

15. Hybrids: 3D Auto-Alignment with 2D Arrays

16. Time of flight  - 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

17. 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…

18. 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 fundamentallycheap 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)

19. Thanks! Student Heroes: Jayasri Akella, sri@networks.ecse.rpi.edu Dr. Murat Yuksel (post-doc): yuksem@ecse.rpi.edu Chang Liu, c.liu@ee.unimelb.edu.au David Partyka, partyd@rpi.edu Sujatha Sridharan Bow-Nan Cheng:chengb@rpi.edu (CWN project) : “shiv rpi”