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Demetris Zeinalipour Assistant Professor Data Management Systems Laboratory Department of Computer Science University of Cyprus http://dmsl.cs.ucy.ac.cy/. Spatio-Temporal WiFi Localization. University of Piraeus.
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Demetris Zeinalipour Assistant Professor Data Management Systems Laboratory Department of Computer Science University of Cyprus http://dmsl.cs.ucy.ac.cy/ Spatio-Temporal WiFi Localization University of Piraeus Final Conference of MOVE COST Action IC903, Vienna, Austria, Sept 30-Oct 1, 2013
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.
Related Work Cywee / Airplace • 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: Demo at ACM Mobisys'13, Taiwan Good
RadioMap (Server Side) • The Server maintains a 2-D MATRIX[N][M] byrecording 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.
RadioMap (Server-Side) I can see these Reference Points, where am I? Cellular WiFi (x,y)! RadioMap Service ... User u Cellular
Anyplace Indoor Navigation TU Wien Demo! RadioMap (Client-site) http://anyplace.cs.ucy.ac.cy/
Temporal VectorMap (TVM) Demo! Bloom Filter (u's APs) WiFi WiFi K=3 Positions RadioMap (server-side) ... User u WiFi
TVM – Bloom Filters Bloom 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. AP1 AP1 AP2 AP2 b
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 numberM of elements we can calculate the amount of false positives produced by the Bloom filter: • False Positive Ratio: • Size of vector:
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
Testbed Issues SmartLab: http://smartlab.cs.ucy.ac.cy/ Static Androids Mobile 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.
Thanks! Questions? Demetris Zeinalipour dzeina@cs.ucy.ac.cy Spatio-Temporal WiFi Localization University of Piraeus Final Conference of MOVE COST Action IC903, Vienna, Austria, Sept 30-Oct 1, 2013