Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 1 Towards Ultra-High-Speed Wireless Distribution Networks Shiv Kalyanaraman, Murat Yuksel, Partha Dutta Supported by NSF Strategic Tech. (STI) & Intel Corp : “shiv rpi”

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 2 Why not have a Moore’s law equivalent for Residential Internet Access? Problems today: 1.FTTH is expensive ($100B+), but game is changing 2.Last-mile telecommunications has a duopoly structure ?

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 3 The Ultra-Broadband Opportunity q Optical networking slowly closing in on the last 10 miles: q Copper and Cable networks still dominate final mile q Wireless is slowly creeping in as a complementary technology: q 3G Mobility, WiFi hot-spots, WiFi LANs q WiMax: will open the era of broadband wireless access (true competitor to DSL, cable modems) q Community wireless networks (CWNs) under experimentation: auto-configured, auto-managed networks q The problem of cheap wireless 1-10 Gbps-to-the-home via wireless technologies is a good stretch target for the next 10 years…

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 4 Ultra-BB Wireless Prognosis made in 1996! q Tim Shepard (MIT) Thesis, and SIGCOMM’96 paper q “… We show that with a modest fraction of the radio spectrum pessimistic assumptions about propagation resulting in maximum possible self- interference and an optimistic view of future signal processing capabilities that a self-organizing packet radio network may scale to millions of stations within a metro area with raw per-station rates in the hundreds of megabits per second…” q Why has wireless ultra-broadband not happened yet? q Need cheap, open wireless MAN technology building blocks q Physical layer innovations (MIMO, OFDM) integrated into open standards q Multi-hop meshes still cannot compete with the cellular model q Need to allow it to truly self-manage (largely!) and scale organically.

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 5 Community Wireless Networks (CWNs) RPI, Troy, NY

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 6 Broadband exists. Why CWN? q Ans: Multiplicity. q Cable modem and DSL and CWN and … q Commodity => cheap to get multiple access facilities … Ethernet WiFi (802.11b) a USB/802.11a/b Firewire/802.11a/b Phone modem

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 7 Multipath P2P Video/Data Over CWNs “Fast” path I “Slow” path P Traffic engineering & Transport level upgrades

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 8 Mixed Model: Infrastructure Wireless/Wired Networks Coexisting with Multi-Hop Ad Hoc Wireless Access WiMax Mesh Network Goals: Ultra high-speeds, Low-costs, Organic, Self-Managed, Complements Wired

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 9 Bringing Optical Communications and Ad Hoc Networking Together… Mobile communication Auto-configuration Free-Space-Optical Communications (FSO) Ad Hoc Networking 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) High bandwidth Low power Directional

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 10 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 11 Ad-Hoc/Meshed Optical Wireless: Why? q Positive points: q High-brightness LEDs (HBLEDs) are very low cost and highly reliable components q cents a piece, and $2-$5 per transreceiver package + upto 10 years lifetime q Very low power consumption (100 microwatts for Mbps!) q Even lower power for 1-10 Mbps q 4-5 orders of magnitude improvement in energy/bit compared to RF q Directional => Huge spatial reuse => multiple parallel channels for huge bandwidth increases due to spectral efficiency q More Secure: Highly directional + small size & weight => low probability of interception (LPI) q Issues: q Need line-of-sight (LOS); and alignment of LOS & network auto-configuration q Need to deal with weather & temporary obstacles, alignment loss Challenge: leverage huge benefits while tackling problems.

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 12 Optical Wireless: Commodity components Many FSO components are very low cost and available for mass production. Lasers… LEDs… VCSELs… IrDAs…

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 13 Spatial Re-use: 2D FSO Arrays: 1-100Gbps Backhaul q 1cm 2 LED/PIN => 1000 pairs in 1ft x 1ft square structure q 100 Gbps aggregate bandwidth (= 1000 x 100 Mbps) Node 1 Node 2 … Node 1 Node 2 Repeater 1 Repeater 2Repeater N-1 D D/N

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 14 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 Kalyanaraman Rensselaer Polytechnic Institute 15 Initial Ad-Hoc FSO Prototypes

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 16 Initial Ad-Hoc FSO Prototypes (contd) Very dense packaging and high mobility are feasible. Misaligned Aligned Received Light Intensity from the moving train.

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 17 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 Kalyanaraman Rensselaer Polytechnic Institute 18 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 Kalyanaraman Rensselaer Polytechnic Institute 19 Indoor Ad-Hoc FSO: Music App (contd)

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 20 Hybrids: 3D Auto-Alignment with 2D Arrays

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 21 Time of flight  - angle of arrival Auto-configuration: Location tracking and management q Location tracking: (optional integration w/ GPS) q Use highly granular spherical FSO antennas (e.g. hundreds of transceivers)  can detect angle of arrival q Use time of flight or signal strength  can detect distance q Unlike RF, no need for triangulation: sense of direction is available. q Allows easy integration with Community Wireless Networks (CWNs) q Organic network growth

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 22 Other Apps: Broadband Sensor Networks: Eg: Camera Networks q Thousands of un-supervised and moving cameras w/o centralized processing or control q Key: Mix of Low Power AND High Speed AND Ad-Hoc/Unsupervised q More than 10,000 public and private cameras in Manhattan, 2.5 million in the UK! q Subways, airports, battlefields, factory floors, highways…

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 23 SUMMARY: Ultra-Broadband Wireless: puzzle falling in place… q (1) Infinite Spectrum in Thin Air! q Key: use unlicensed spectrum or larger licensed bands q (2) Multi-hop architecture w/ Base-Station Interfaces q Wireless is fundamentally cheap for shorter distances, smaller coverage q Organic architecture: auto-conf, self-management (10+ years of research in ad-hoc networks), community wireless q IP/geographic routing, fully distributed traffic engineering mechanisms q Technology neutral, extensible, modular: x, x, FSO q (2a) Multi-hop Free-space-optics (FSO) using ultra-low-cost components for 100 Gbps+ capabilities q Key: Broadband CWNs & ad-hoc FSO complementary to ongoing advances in FTTH, DSL/Cable, WiMax, 3G rollouts. q 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 24 Thanks! : “shiv rpi” Student Heroes: Jayasri Akella, Dr. Murat Yuksel (post-doc): Chang Liu, David Partyka, Sujatha Sridharan Bow-Nan Cheng: (CWN

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 25 Free-Space-Optical (FSO) Ad-Hoc Networks: Mobile or Fixed Multi-Hop Application: Mixed RF/FSO Ad-Hoc Networks (Military Application)

Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 26 Aggregate Capacity in 2-d Arrays: Interference vs Density vs Distance Bandwidth-Volume Product Interference Error vs. Packaging Density