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
Piraeus