1. Download from http://research.microsoft.com/~jckrumm/NearMe.htm The NearMe Wireless Proximity Server John Krumm and Ken Hinckley Microsoft Research Redmond, WA, USA

2. Download from http://research.microsoft.com/~jckrumm/NearMe.htm The Basic Idea 802.11 Wi-Fi access point NearMe Proximity Server

3. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Location vs. Proximity s 1 = measured signals s 2 = measured signals x 1 = (x,y) location x 2 = (x,y) location d 12 = f(x 1, x 2 ) d 12 = g(s 1, s 2 )

4. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Who Cares? Schilit, Adams, & Want, “Context-Aware Computing Applications”, 1994. Which of my friends, colleagues, relatives, or enemies are nearby? Who are these strangers with me? What are the names of nearby printers? What conference rooms are nearby? How far away is the nearest receptionist desk? Other elements of context: velocity, mode of transportation, task, goal, mood …

5. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Other Proximity Methods Location from Active badges Cameras Wi-Fi GPS Cell Phones … Conference Devices SpotMe nTAG TM IntelliBadge TM - NCSA Conference Assistant – Georgia Tech Proxy Lady – Viktoria Institute Digital Assistant – ATR Synchronous Context Synchronous Gestures – Microsoft “Are You With Me?” – U. Washington SyncTap – Sony Stitching – Microsoft Smart-Its Friends – Disappearing Computer Initiative SpotMenTAG TM Services Trepia iChat – Apple Short Range Networking Infrared Bluetooth

6. Download from http://research.microsoft.com/~jckrumm/NearMe.htm NearMe Client Windows XP PocketPC 2003 Requirements: Windows XP WWW access Microsoft.NET Framework

7. Download from http://research.microsoft.com/~jckrumm/NearMe.htm NearMe Client – Test Connections

8. Download from http://research.microsoft.com/~jckrumm/NearMe.htm NearMe Client – Register Register with: Name Email (optional) URL (optional) Expiration interval

9. Download from http://research.microsoft.com/~jckrumm/NearMe.htm NearMe Client – Report Wi-Fi List of detectable Wi-Fi access points Access points used only as beacons Periodic reports for mobility

10. Download from http://research.microsoft.com/~jckrumm/NearMe.htm NearMe Client -- Query Adjustable “Look back” time to filter outdated reports

11. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Register as thing NearMe Client – Nearby Things personelevatorkitchenbathroom conference roomstairsmail roomstitchable device printercafeteriareception deskdemo person Report signal strengths Query for things

12. Download from http://research.microsoft.com/~jckrumm/NearMe.htm NearMe Server SQL Server.NET Web ServiceClients

13. Download from http://research.microsoft.com/~jckrumm/NearMe.htm NearMe Server Data Expiration deletes source of Wi-Fi data, but not Wi-Fi data itself

14. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Access Point Layout 2 1 3 A F B D C E F A B C D E Access point topology in database Recomputed every hour

15. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Hops = Distance Estimate Extends proximity range beyond radio range

16. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Access Point Travel Times Minimum observed client travel time between access points Recomputed every hour Could be computed from other “wardriving” data, e.g. Intel Research Place Lab NetStumbler To Do Path plan, e.g. A→C = A→B + B→C Cluster times, e.g. times for walk, bike, drive

17. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Travel Times = Distance Estimate Observed lower bound on travel time

18. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Distance Estimation How to estimate distance between things?

19. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Distance Functions Wi-Fi Signature = s = { (mac 1, rssi 1 ), (mac 2, rssi 2 ), …, {(mac n, rssi n ) } Candidate Distance Features: 1.n ∩ = number of access points in common 2.ssd ∩ = sum of squared differences of rssi in common 3.n u = number of access points not in common 4.ρ s = Spearman rank coefficient of access points in common sasa sbsb d = f(s a,s b )

20. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Compare Ranked Signal Strengths mac 1 mac 2 mac 3 mac 2 mac 3 Spearman rank = ρ s -1 <= ρ s <= 1 “RightSPOT”, UbiComp 2003

21. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Distance Functions d = f(s a,s b ) d = f(n ∩, ssd ∩, n u, ρ s ) Example: d = a∙n ∩ 2 + b∙ssd ∩ + c∙n u 3 + d∙ρ s 4 features + polynomials to 3 rd degree = 45 different test functions

22. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Test Data Wi-Fi Cards 1.Dell built-in laptop 2.Microsoft Wireless USB 3.ORiNOCO PC Card 4.Actiontec USB 5.Cisco Aironet PC Card 6.Linksys USB Office Building:1,441,739 pairs Cafeteria: 572,027 pairs

23. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Simple Distance Function d = -2.53∙ n ∩ – 2.90∙ ρ s - 22.31 rms error = 14.04 meters ρ s = 0.39

24. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Applications Look up URLs of nearby people Send email to people nearby Stitching

25. Download from http://research.microsoft.com/~jckrumm/NearMe.htm What Makes NearMe Different? Works on existing Wi-Fi devices Minimal setup –“Out of the box” for nearby people –Capability grows with use Short range proximity –Accounts for different Wi-Fi hardware –Sorted by distance Long range proximity –Hop distances via adjacency analysis –Travel times via timestamp analysis

26. Download from http://research.microsoft.com/~jckrumm/NearMe.htm Demo