SmartTrace Crowdsourced Trace Similarity with Smartphones

Demetrios Zeinalipour-Yazti, Christos Laoudias, Constantinos Costa, Michail Vlachos, Maria I. Andreou, Dimitrios Gunopulos

University of Cyprus, IBM Research Zurich, Open University of Cyprus and University of Athens

Similarity Comparison

ignore majority of noise

•

Goals and Contributions Problem:

Find the K users moving more similarly to a query trajectory Q, in a Smartphone Network.

• Privacy: User trajectories and User identities are • not disclosed to the Query Processor.

Performance: a) In-situ data storage of trajectories (on

smartphone flash) and b) Query Processing using a Top-

K Query Processing Algorithm that uses Bound Scores* Ubiquity: Our system works both outdoors (using GPS)

and indoors (using WLAN Signal Strength)

match match

– –

Flexible matching in time (ignore temporal noise) Flexible matching in space (ignore spatial noise)

System Model The SmartTrace Framework High Level Idea Performance Evaluation Smartphone Energy: ↓ 81% Server Console

SmartTrace Outdoors (GPS)

Android-based Smartphone Implementation “No Sharing” Policy

SmartTrace Indoors (WLAN RSS)

Server

• Ubuntu Linux • JDK 6, ~1500 LOC

Client

• HTC Desire smartphones • Android 2.1 (Eclair) • Google Map API • ~2500 LOC, ~250 lines XML • 510KB installation package APK • Runs on Dalvik VM (future: native C with Android NDK)

SmartTrace Client GUI

• Query devices by example • Plot and iterate through the responses using a variety of presentation styles • Configure parameters (e.g. K) • Control privacy settings • Online/Offline modes for recorded scenario playback • GPS/WiFi modes

Indoor scenario at KIOS Research Center

• 560m 2 area, 3 APs, 1 Query (Q) RSS trajectory • 4 other (T1-T4) RSS trajectories, top-2 search •

T2 and T3 correctly identified as top-2 answers

"Crowdsourced Trace Similarity with Smartphones", Demetrios Zeinalipour-Yazti and Christos Laoudias and Constandinos Costa and Michail Vlachos and Maria I. Andreou and Dimitrios Gunopulos, IEEE Transactions on Knowledge and Data Engineering (TKDE '13), IEEE Computer Society, Volume 25, Pages: 1240-1253, Los Alamitos, CA, USA, 2013.

"Disclosure-Free GPS Trace Search in Smartphone Networks", Demetrios Zeinalipour-Yazti, Christos Laoudias, Maria I. Andreou, Dimitrios Gunopulos, "Proceedings of the 2011 IEEE 12th International Conference on Mobile Data Management - Volume 01" (MDM '11), IEEE Computer Society, Pages: 78--87, Washington, DC, USA, ISBN: 978-0-7695-4436-6, 2011.

"SmartTrace: Finding similar trajectories in smartphone networks without disclosing the traces", Constandinos Costa, Christos Laoudias, Demetrios ZeinalipourYazti, Dimitrios Gunopulos, "Proceedings of the 2011 IEEE 27th International Conference on Data Engineering" (ICDE '11), IEEE Computer Society, Pages: 1288--1291, Washington, DC, USA, ISBN: 978-1-4244-8959-6, 2011.

Data Management Systems Laboratory Web: http://smarttrace.cs.ucy.ac.cy/ Email: [email protected]

Acknowledgements: This work was supported in part the third author’s Startup Grant, EU’s FP6 Marie Curie TOK “SEARCHiN” project, EU’s FP7 CONET project and EU’s FP7 “SemSorGrid4Env” and “MODAP” projects.