Wireless Location Technologies

Nobuo Kawaguchi

Graduate School of Eng.Nagoya University

Today’s Topic

Wireless Location Technologies What is WiFi based Positioning HistoryCharacteristics

WiFi Location Database Wireless Location Information Systems

PlaceLab Skyhook Wireless Loki PlaceEngine Locky.jp Apple iPhone

Location Enhanced Services

1m 10m 100m

Estimation Accuracy

Env

iron

men

t

PHS

GPS

Outdoors

Indoors

CellPhone

Ultra Sonic RFID

UWB

Wireless LAN

Wireless Location Technologies Tech. for both Indoor / Outdoor is required

WiFi Everywhere

Wireless LAN has become popular infrastructure A large number of position estimation system

using wireless LAN have been developed

Station

Home

Restaurant

Airport

Wide spread of wireless LAN

RSSI

BSSID, Latitude, Longitude

University

Company

WiFi location

WiFi Location Technology Every WiFi Access Point(AP) has followings

ESSID 　 (String) BSSID 　 6 byte vendor assigned unique address

(MAC) Construct a database with BSSID and Position

One can estimate the position just receive a WiFi BSSID.

A lot of WiFi APs are already exist in the Wild.

One can easily add new APs by oneself. Can increase accuracy by adding APs. Each AP do not requires network access for positioning.

Important Points

now

2000:RADAR(Microsoft)

2000:Ekahau

2005/7:Locky.jp(Nagoya Univ)

2006/7:PlaceEngine(Sony CSL)

History of WLAN positioning

Start around 2000 (MS RADER)

2006/3:Loki(Skyhook Wireless)

2003:AirLocation(Hitachi)

2003:PlaceLab(Intel)

Service/Activities

Products

Technology

2007/9:Digial Camera(Sony)

2008/1:iPhone (Apple)

Triangulation Lateration (RSSI or TDOA)

RADAR (MS Research), WiPS (Kyusyu Univ. Japan)

AirLocation (TDOA)(Hitachi) Angulation (AOA)

Proximity GUIDE Project (Keith et al)

Scene Analysis RADAR(MS Research), Ekahau (Ekahau corp.) Place Lab (Intel Research)

Existing methods are classified into following three types.

Positioning methods using WLAN

Positioning Access Point

Triangulation

Using more than 3 reference point’s distance

Using more than 2 reference points direction

AB

C

a b

c

E

AB

E

α

β

(Lateration)(Angulation)

Reference PointEstimated Point

Reference Direction

Positioning Access Point Proximity

Consider the position of most powerful APas a current position.

Transmission range of Wireless LAN is about 100 meters in the open air

Not good accuracy but simple.

Scene Analysis Consider Difficult to construct learning data as target area is

spread Inappropriate for our objective

Terminal’s location

APn(xn,yn)

AP2(x2,y2)Reference Point

AP1(x1,y1)

Communication Area of Reference Point

This method consider communication area of AP as user’s position.

Proximity

Lecture RoomA

Lecture RoomB

Lecture RoomC

Lecture RoomD

Lecture RoomE

This method use pre-observation wireless information called radio map.

Most system use Monte Carlo family method (ex. Bayesian filter, particle filter) and radio map.

Scene Analysis

GPS vs WiFi Location

From , Delivering Real-World Ubiquitous Location Systems, C. ACM 2006.

WiFi Location: Characteristics

WiFi characteristicsDifference of WLAN Adapter/AntennasDifference on OrientationWiFi Signal Strength Distribtion

WiFi Positioning AcitivitiesLocky.jp Project

WiFi AP positioning

Difference on WLAN Adapter

Wireless LAN Adapter B

Wireless LAN Adapter A

Distribution Difference

0º

45º315º

225º 135º

90º270º

180º

Wireless LAN Card A

Wireless LAN Card B

Wireless LAN Card C

Difference on Orientation

Received Signal Strength (dBm)

Prob

abil

ity

Den

sity

0

0.05

0.1

0.15

0.2

0.25

-60 -55 -50 -45 -40

Distribution Pattern of WiFi RSSI

WiFi Location Database

Required for wide area location system. Acquisition Method

AccuracyEfficiency

How to construct a large DatabaseLocky.jp

Acquisition Methods Variety of acquisition methods with different transportation

Car30km/h

Bicycle15km/h

Walking5km/h

Near to the buildings and houses

Influenced by traffic jams and regulations

20%

30%

40%

50%

60%

70%

80%

90%

100%

Learning　Data　(　Walking　)Learning　Data　(　Bicycle　)Learning　Data　(　Car　)

Estimation Accuracy

The position estimation using the learning data acquired by walking can make estimates at less than 30m in 63% of the area

The estimation data by car is worse by about 5% in all ranges Beyond 40 m, the bicycle data can estimate almost as well as that

obtained by walking

Cumulative estimation accuracy of evaluative data by walkingAccuracy(m)

Cum

ulat

ive

rate

0

0.1

0.2

0.3

0.4 Car

Motor Bike

Bicycle

0-20 21-40 41-60 61-80 81-100 101- unknown

Pro

babi

lity

Den

sity

Accuracy (m)

Car

Motor Bike

Bicycle

Accuracy of WiFi location

Result: Bicycle is more suitable than Others

Bicycle has better efficiency than others

Walking

(5km/h)

Bicycle

(15km/h)

Car

(30km/h)

All data

No. of APs 247 269 183

Accuracy (m) 24.3 26.7 29.6

Coverage (%)

86.8 87.8 83.3

First-round data

No. of APs 214 209 122

Accuracy (m) 31.3 23.2 26.0

Coverage (%)

72.2 74.6 68.2

Strong signal APs

(1st round) (RSSI > -90)

No. of APs 155 178 49

Accuracy (m) 30.1 23.5 32.9

Coverage (%) 68.1 73.2 53.8

Table: Position Estimation of Experimental data （ Walking, Proximity ）

GPS

Note PC

WiFi Antenna / Card

Battery

Stumbler

WarDriving using bycicle

Locky.jp Project

Locky.jp 　 Project

WiFi Location Portal for JapanData Collection of WiFi AP(BSSID) + LocationPlace Information

Begins July 2005

Currently, we have collected

369,045 APs currently

Locky.jp

Goals of Locky.jp Wide-area WiFi Location acquisition by collaboration with user Creation of position estimation system using WiFi Location database Producing Low-Cost positioning system for everywhere everybody

Activity Research on positioning system Public relations of positioning system Creation of acquisition assistance tools

Locky.jp

Environment full of wireless LAN

Users

WiFi　LocationDatabase

Information Service

WiFi Location

Effect on …Service areaEstimation accuracy

WiFi LocationWiFi LocationWiFi Location

Collecting AP’s by Collaborators

300 over members collecting AP

Mainly for Tokyo/Osaka/Nagoya - Ranking

Trend of No. of AP in Locky.jp

Over 530,000 WiFi locations in Japan

0

50000

100000

150000

200000

250000

Oct-05

Nov-05

Dec-05

J an-06

Feb-06

Mar-06

Apr-06

May-06

J un-06

J ul-06

Aug-06

Sep-06

0

20

40

60

80

100

120

WiFiUser

Month

No. of collaboratorNo. of AP

Tokyo area ( over 50000 AP)

Tokyo APs plotted on GoogleEarth

View from Tokyo-Castle

　 Nagoya Area , Over 40000APs

Access Point

Total 8788.8 unit / 100m×100m

1km

Access Points in Nagoya City Area

1km Square878 APs

Center of NagoyaJAPAN

Access Point

Total 2783.5 unit /100m×100m

Residential Area

APs in Residential Area

1km

Residential areaHeight is restricted

278 APs in 1km square area

Locky.jp upload page

Tools for Locky.jp

Locky Stumbler

KML converterLog→ KML (Google Earth)

Wireless Location Lib for WLDB

Locky ToolkitBy using Locky Toolkit, one can easily

develop a WiFi Location ApplicationJust a few line of Java code.

//　Creation　of　LockyToolkit　objectLockyToolkit　lockyToolkit　=　new　LockyToolkit();

//　Load　a　WiFi　Location　DBlockyToolkit.openDB();

//　Get　Locky　Code　from　current　wireless　measurementLockyCode　lockyCode　=　lockyToolkit.getLockyCode();

//　Get　latitide,　Longitudedouble　latitude　=　lockyCode.getLatitude();double　longitude　=　lockyCode.getLongitude();

Locky Toolkit example program （ Java ）

Bootstrapping Location-enhanced ComputingEnabling privacy-observant, wide scale, indoor & outdoor device positioning with low barriers to participation

Research Agenda• Previous research: small communities, high cost systems

• Our goal: enable large communities by reducing barriers to adoption

• Provide low-cost, highly convenient position-sensing technology

• Make users comfortable with respect to their location privacy

• Develop services and toolkits to make it easy to build location-aware applicationsUsage Model

Client devices cache snapshots of WiFi Beacon Databases

Applications use location to provide customized, dynamic

content and services

Devices that hear WiFi beacons estimate location locally & privately.

New beacons get added to user-contributed database

Urban areas have dense WiFi coverage

PlaceLab Approach • Rely on increasing WiFi densities to provide low-cost device positioning

• Build a public user-contributed data store to map RF beacons to geographic locations

• Improve quality of positioning data via Bayesian filter and sensor fusion techniques

• Understand privacy management tradeoffs by studying use of location-aware applications

• Provide a “PlaceLab” for educators with toolkits and curriculum for web and ubicomp courses

• Offer developers a mechanism to use “place” abstractions in addition to low-level coordinates(Reference http://www.placelab.org/ )

PlaceLab （２００３ ~ Intel Research)

Skyhook wireless

Loki

200 employee

8million APs

http://loki.com/

　 Loki Toolbar

By using the Loki toolbar, one can locate the place of the terminal in major cities in U.S.

PlaceEngine by Sony CSL

You can upload theWiFi Info to PlaceEngine Serverusing Web Service

(Reference http://www.placeengine.com/ )

PlaceEngine

Web service for WLAN location 200,000 access point in Tokyo area.

(Reference http://www.placeengine.com/ )

PlaceEngine 150,000 access point in Tokyo area.

Mash up with PlaceEngine

PlaceEngine can be used as a Web parts.

PlaceEngine Client

Web Browser

PlaceEngineWeb DB

Web Service

PE button

Your PC

PlaceEngine×Station Info.

PlaceEngine can be used as a Web parts.

PlaceEngine × Restaurant Search

PlaceEngine × Restaurant Search

Asked to send “location” to Web Application

PlaceEngine × Restaurant Search

Apple iPhone

Apple iPhone utilize WiFi Positioning System by Skyhook Wirelessand GSM Location System by Google.

Google Maps for Mobile

"My Location" Technology

http://www.google.com/intl/en/press/annc/20071128_maps_mobile_my_location.html

Adds a GSM Location technology ontomobile phones

Do not require GPS (only 15% of mobile phone has GPS)

Community:

War Driving Communityhttp://wigle.net

12,886,129 points from 796,376,798 person

(2008/01/23)

Mostly for use WiFi Hotspot.Not for positioning.

Applications of WLAN Positioning

Beacon Print (Intel Research: UbiComp2005)Detect User’s Preferred PlacesDo not require pre-acquisition

NearMe (MS Research:UbiComp2004)Wireless Proximity

Detect near person using BSSID

Self organization of WLAN AP dataPlaceEngine uses this technology

WiFi Tagged Photo Exif for JPEG

Date , Time , other photo data add WiFi BSSID.. ||Location Enhanced Photo

If you put photos on Flickr with BSSID, You can find the closer photos.With WiFi tag, and WiFi Location DB,

You can find the photo using Place.

This does not require offline WiFi location database

Digital camera with WiFi is now on Market

Utilization of WiFi Location System

Location systems are widely spreadBut not for WiFi Location System

GPS is primary location sourceA lot of GPS application are public

NMEA format

We need integrate WLS with GPS

Implementation of Virtual GPS

Virtual COM driverGPS Application

Get NMEA data from COM port

Virtual COM Driver

Locky VirtualGPS

WiFi

WLDB

COM X COM Y

NMEAoutput

Hybrid Positioning with GPS

Virtual COM driverGPS Application

Get NMEA data from COM port

Virtual COM Driver

Locky VirtualGPS

WiFi

WLDB

COM X COM Y

NMEAoutput

GPS

Selection module

Indoor positioning for public area

Outdoors data can be easily collected Locky.jp tool (GPS+ WiFi)

How to collect data for indoor area.There is no way to locate position.We need some tool for data acquisition.

Which place we should collect?Public place with WiFi

Subway of Nagoya

We have WiFi on all stations

We collected underground WiFi

Map of undergroundUse a photo of floor map.

Plot a location by Hand on the photo.Any place can be collected with this tool.Other data can be offered with Photo.

Subway Stumbler

We have developed a tool for indoors

How many data have we collected?

Current Subway WiFi data.83 Nagoya Subway Stations 30 person-day2000 Unique APs82500 point of locations

How many data have we collected?

Current Subway WiFi data.83 Nagoya Subway Stations 30 day collection2000 Unique APs82500 point of locations

Only 30 day are required to collect subway data in Nagoya ( 2 million city )

Location Processing

Subway knowledgeTime table

Arrival time can be estimate

There are shops in the station.RestroomsExchange station

It is not only a location information

Possible Applications

Train Navigation with “Time”

Exit navigation

If you collect WiFi data every seconds,Your route is stored in the device.Station/Route can be estimated.

　 →　 Train fee is easily calculated.

Underground Map of Nagoya

ALPSLAB Underground(Since 2007/12)

We already collected WiFi

Total Unique Sakae Area AP = 160 Nagoya Station AP ： 241

Experiment with iPod Touch

Writing 　 Enquate

FriendMap

Shows the position of Friends and Chat

iNavi

Location Dependent Database

Input Query Result set Infomation

NextTrain

Realtime TimeTable

Station Map Countdown for next train

Realtime Train Map

Shows position of trains by time-table

Shows current position Trace the train

Station Map

Maps for underground station

U Underground Map

Summary

Wireless Location TechnologyWith WiFi, one can easily estimate one’s

position Collection of WiFi Location Database

Locky.jp

Experiment in Real In-door EnvironmentNagoya Subway