Spatio-Temporal WiFi Localization

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

1© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

Final Conference of MOVE COST Action IC903, Vienna, Austria, Sept 30-Oct 1, 2013

Spatio-Temporal WiFi Localization

Demetris Zeinalipour

Assistant Professor

Data Management Systems Laboratory

Department of Computer Science

University of Cyprus

http://dmsl.cs.ucy.ac.cy/University of

Piraeus

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

2© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

Motivation• People spend 80-90% of their time inside buildings,

while 70% of cellular calls and 80% of data connections originate from indoors.

• GPS has low availability indoors due to the blockage or attenuation of the satellite signals, alternative geolocation solutions are required.

• Smartphones can nowadays localize off-the-shelf with onboard sensors and WiFi signal fingerprints (coined Hybrid Localization)

• New Applications:– In-building Navigation (Malls, Airports, Museums, Schools, etc.)– Asset Tracking and Inventory Management (Hospitals, etc)– Elderly support for Ambient and Assisted Living (AAL) – Augmented Reality (Firefighters), Social Networking, etc.

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

3© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

Related Work• Indoor Localization using proprietary

infrastructure: Infrared, Bluetooth, Visual or Acoustic Analysis, RFID, Inertial Measurement Units, Ultra-Wide-Band, Wireless Sensor Network, Wireless LAN,

• IMU+WifI (acceler., gyro, digital compass) MapMatching, Magnetic Data, pedometer

• Smartphone Localization:

Good

Cywee / Airplace

Demo at ACM Mobisys'13,

Taiwan

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

4© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

RadioMap (Server Side)

• The Server maintains a 2-D MATRIX[N][M] by recording the RSS values of M APs at N geo-locations (x,y)

• For example, Radiomap MATRIX format:AP1, AP2, .... APM => x1,y1

AP1, AP2, .... APM => x2,y2

AP1, AP2, .... APM => x3,y3

....

AP1, AP2, .... APM => xN,yN

• typically constructed by centrally overlaying several RSS vectors.

4

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

5© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

RadioMap (Server-Side)

RadioMap Service

Cellular

WiFi

Cellular

...

I can see these Reference Points,

where am I?

(x,y)!

User u

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

6© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

Anyplace Indoor Navigation

http://anyplace.cs.ucy.ac.cy/

TU Wien Demo!RadioMap (Client-site)

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

7© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

Temporal VectorMap (TVM)

RadioMap (server-side)

WiFi

WiFi

WiFi

...

Bloom Filter (u's APs)

K=3 Positions

User u

Demo!

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

8© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

TVM – Bloom FiltersBloom filters – basic idea:

- allocate a vector of b bits, initially all set to 0- use h independent hash functions to hash every

Access Point seen by a user to the vector.

To test whether an element is a member of a set:- compare the vector of the query to the RadioMap on

the server.

0 1 0 0 1 0 0 1 0 0

AP1AP1AP2 AP2

b

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

9© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

TVM – Bloom Filters

• The most significant feature of Bloom filters is that there is a clear tradeoff between b and the probability of a false positive

• Given h optimal hash functions, b bits for the Bloom filter and the number M of elements we can calculate the amount of false positives produced by the Bloom filter:

– False Positive Ratio:

– Size of vector:

h-hM/b )e-(1 fpr

)fpr-ln(1

hM- b

h

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

10© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

TVM Continuous

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

11© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

References• Anyplace Website: http://anyplace.cs.ucy.ac.cy/• Privacy-Preserving Indoor Localization on Smartphones with Vectormap,

Andreas Konstantinidis, Paschalis Mpeis, Demetrios Zeinalipour-Yazti and Yannis Theodoridis, in preparation.

• "Demo: Indoor Geolocation on Multi-Sensor Smartphones", C.-L. Li, C. Laoudias, G. Larkou, Y.-K. Tsai, D. Zeinalipour-Yazti and C. G. Panayiotou, In ACM Mobisys '13, Taipei, Taiwan, 2013.

• "The Airplace Indoor Positioning Platform for Android Smartphones", C. Laoudias, G. Constantinou, M. Constantinides, S. Nicolaou, D. Zeinalipour-Yazti, C. G. Panayiotou, In IEEE MDM'12, Bangalore, India, 2012 (Best Demo Award)

• "Towards planet-scale localization on smartphones with a partial radiomap", A. Konstantinidis, G. Chatzimilioudis, C. Laoudias, S. Nicolaou and D. Zeinalipour-Yazti. In ACM HotPlanet'12, in conjunction with ACM MobiSys '12, ACM, Pages: 9--14, 2012.

• "Demo: the airplace indoor positioning platform", C. Laoudias, G. Constantinou, M. Constantinides, S. Nicolaou, D. Zeinalipour-Yazti and C. G. Panayiotou, In ACM Mobisys'12, 2012

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

12© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

Testbed Issues

SmartLab: http://smartlab.cs.ucy.ac.cy/

Static Androids["Demo: a programming cloud of smartphones", A. Konstantinidis, C. Costa, G. Larkou, D. Zeinalipour-Yazti, In ACM Mobisys'12."Managing Smartphone Testbeds with SmartLab", G. Larkou, C. Costa, P. Andreou, A. Konstantinidis, D. Zeinalipour-Yazti , In USENIX LISA'13.

Mobile Androids

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

13© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

Testbed Issues

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

14© Konstantinides, Mpeis, Zeinalipour-Yazti, Theodoridis

Final Conference of MOVE COST Action IC903, Vienna, Austria, Sept 30-Oct 1, 2013

Spatio-Temporal WiFi Localization

Thanks!

Questions?

Demetris Zeinalipour

dzeina@cs.ucy.ac.cyUniversity of

Piraeus