Naam, AfdelingNaam, Afdeling

07/01/2009

To localise or to be localised with Wi-Fi in the Hubei Museum?Edward Verbree, Sisi Zlatanova, Karl van Winden, Eva van der Laan, Antigoni Makri, Li Taizhou, Ai Haojun

Introduction

• MSc Geomatics - DaRen Syntheses Project• Hubei Provincial Museum – Wuhan China• Localisation• Wi-Fi Fingerprinting• Wi-Fi Monitoring• Wi-Fi Monitored Fingerprinting

Introduction

• The overall goal of the project is to investigate the potential of a 3D indoor navigation systems and raise awareness of the possibilities provided by the technology for every-day users.

• This goal is achieved by creating a 3D multi-purpose

indoor navigation application named DaRen • Chinese words Da “intelligence, accessibility” and Ren

“people”

Hubei Provincial Museum

ApplicationNavigation

• Localisation• Routing• Visualisation

LocalisationResearch Question

What are the possibilities of Wi-Fi monitoring in comparison to the commonly known fingerprinting method for the purpose of a 3D indoor navigation system?

LocalisationGranularity

• Localisation ≠ (Point) Positioning• Localisation = Place oriented (floor, room, exhibition)• Localisation = Needed as starting place for routing• Localisation = Needed for location based services (sec)

Wi-Fi Fingerprinting

•Existing WLAN-infrastructure can be used•Every second a location can be given•No privacy issues regarding storage of locations

1.Measurements of Signal StrengthReference Points

2.Creation of Radio Map3.Location Determination

Reference Points

Measuring Procedure

• Offline / Training Phase:• Measurements RSS have been performed in 4 directions• Time of measuring: 1 minute / direction

• Creating probability radio map:• Consists of mean value and standard deviation

• Online / Localisation:• Calculating the most probable location

Wi-Fi FingerprintingResults

High Spatial Resolution of Reference Points+Probabilistic RSS values=Accurate Localisation

Implemented @ Wuhan University

Wi-Fi FingerprintingLimitation

• Device driven (Wi-Fi scanning)• Apple devices excluded

• ‘Space segment’ (Wi-Fi Access Points) not under control• Access Point re-configuration requires update of radio map

Wi-Fi MonitoringMeshlium Xtreme

Wi-Fi Monitoring

• Beacon frames• Send by ALL mobile devices (smartphones, laptops, etc.) in order to connect to

Access Point• Iff Wi-Fi is on (Free Internet in Museum)• Device doesn’t have to be connected

• Wi-Fi Monitor – Meshlium Xtreme: Receives and stores • MAC-address, • Strength of Signal Indicator (%), • Timestamp (Date/Time), • Vendor (Apple, Samsung, Nokia, etc)

• Advantages• No additional application is required to acquire RSSI• Data can be stored at an external database, which can be used to provide

information to museum and users every moment of the day

Wi-Fi MonitoringApplications

• Localisation• Proximity (near) to Wi-Fi monitor• Distance to monitor

• RSSI gives indication in ‘open’ space

• Wi-Fi Monitored Fingerprinting possible• Business information

• Count of (Wi-Fi enabled) visitors• Time spent at exhibation• Direction of movement of visitors (with two or more monitors)• Crowd control• No need of installed app, no user-involvement

Wi-Fi MonitoringLimitation

• Relies on probe request frames of devices

• Interval between two successful scans can be large

• Not all mobile devices were scanned• Newer types of devices > update of firmware of monitor

• Privacy Issues: Renew Recycling Bins• “City of London bans data-collecting Wi-Fi smart bins

Wi-Fi Monitored FingerprintingTest

• Two Meshlium Xtreme Wi-Fi Monitors part of Access Point configuration while creating radio-map

• Correlation determined between RSSI (Monitor) and RSS (devices)• RSSI Radio Map created for each Monitor

Wi-Fi Monitored Fingerprinting

• RSSI Radio Map First monitor

Wi-Fi MonitoredFingerprinting

• Where am I?

RSSI ‘Distance’to First Monitor

RSSI ‘Distance’to Second Monitor

Wi-Fi MonitoredProbability map

To localise or to be localisedConclusions

To localise (to sniff)App needed at devices (if possible)Happy few (early adopters)Wi-Fi infrastructure not under control for localisation purposes

or

To be localised (to be sniffed)Web-application can be used at devicesEveryone (Free Internet)Dedicated Wi-Fi-Monitors under control for localisation purposes