Download from The NearMe Wireless Proximity Server John Krumm and Ken Hinckley Microsoft Research Redmond, WA, USA

Download from The Basic Idea Wi-Fi access point NearMe Proximity Server

Download from 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 )

Download from Who Cares? Schilit, Adams, & Want, “Context-Aware Computing Applications”, 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 …

Download from 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

Download from NearMe Client Windows XP PocketPC 2003 Requirements: Windows XP WWW access Microsoft.NET Framework

Download from NearMe Client – Test Connections

Download from NearMe Client – Register Register with: Name (optional) URL (optional) Expiration interval

Download from NearMe Client – Report Wi-Fi List of detectable Wi-Fi access points Access points used only as beacons Periodic reports for mobility

Download from NearMe Client -- Query Adjustable “Look back” time to filter outdated reports

Download from Register as thing NearMe Client – Nearby Things personelevatorkitchenbathroom conference roomstairsmail roomstitchable device printercafeteriareception deskdemo person Report signal strengths Query for things

Download from NearMe Server SQL Server.NET Web ServiceClients

Download from NearMe Server Data Expiration deletes source of Wi-Fi data, but not Wi-Fi data itself

Download from Access Point Layout A F B D C E F A B C D E Access point topology in database Recomputed every hour

Download from Hops = Distance Estimate Extends proximity range beyond radio range

Download from 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

Download from Travel Times = Distance Estimate Observed lower bound on travel time

Download from Distance Estimation How to estimate distance between things?

Download from 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 )

Download from 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

Download from 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

Download from 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

Download from Simple Distance Function d = -2.53∙ n ∩ – 2.90∙ ρ s rms error = meters ρ s = 0.39

Download from Applications Look up URLs of nearby people Send to people nearby Stitching

Download from 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

Download from Demo