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Factors effecting positional accuracy of iBeacons

Factors effecting positional accuracy of iBeacons . Chris Thomson ( chris@codepilots.com ) . Background. Indoor localization. ?. Where am I. Small (50x30mm) Cheap (£8-30 per beacon) Range of up to 75m Battery powered Supported by Apple (unlike RFID tags). iBeacons.

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Factors effecting positional accuracy of iBeacons

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  1. Factors effecting positional accuracy of iBeacons

    Chris Thomson (chris@codepilots.com)
  2. Background
  3. Indoor localization ? Where am I
  4. Small (50x30mm) Cheap (£8-30 per beacon) Range of up to 75m Battery powered Supported by Apple (unlike RFID tags) iBeacons
  5. Distance to a iBeacon Anon (2014) 'Adjust beacon range with Estimote’s new App and change UUID using Estimote’s new SDK', Reality matters [Online]. 28/1/2014. Available at http://blog.estimote.com/post/74816977799/estimote-app-v1-2 (Accessed 19/3/2014).
  6. iBeacon localization Estimote iBeacons, from http://estimote.com
  7. The only maths: distance Qiu, T, Zhou, Y, Xia, F, Jin, N, & Feng, L 2012, 'A localization strategy based on n-times trilateral centroid with weight', International Journal Of Communication Systems, 25, 9, pp. 1160-1177, Academic Search Complete, EBSCOhost, viewed 18 March 2014. Bulusu, N, Heidemann, J, & Estrin, D n.d., 'GPS-less low-cost outdoor localization for very small devices', Ieee Personal Communications, 7, 5, pp. 28-34, Science Citation Index, EBSCOhost, viewed 18 March 2014.
  8. Bayesian learning (Öktem& Aydin, 2010) Real-time reference measurements (Hyo-Sung & Wonpil 2009) Clever uses of the radio (Wu et al, 2013) Overcoming Environmental factors Öktem R, & Aydin, E 2010, 'An RFID based indoor tracking method for navigating visually impaired people', Turkish Journal Of Electrical Engineering & Computer Sciences, 18, 2, pp. 185-196, Academic Search Complete, EBSCOhost, viewed 18 March 2014. Hyo-Sung, A, & Wonpil, Y 2009, 'Environmental-Adaptive RSSI-Based Indoor Localization', IEEE Transactions On Automation Science & Engineering, 6, 4, pp. 626-633, Business Source Complete, EBSCOhost, viewed 18 March 2014. Wu, K, Xiao, J, Yi, Y, Chen, D, Luo, X, & Ni, L 2013, 'CSI-Based Indoor Localization', IEEE Transactions On Parallel & Distributed Systems, 24, 7, pp. 1300-1309, Business Source Complete, EBSCOhost, viewed 18 March 2014.
  9. Differences in devices: Tablets, Smart phones and iBeacons Noisy environments Objects in the environment Cost of deployment and maintenance Limited access to raw hardware Practical issues to consider
  10. Solutions?
  11. 4mx3m Test ‘Lab’ IPad Air (2013 wi-fi only model) 3 Estimote pre-production iBeacons (early 2014) Core Location SDK and Estimote SDK Trilateration algorithm (wwnick &Austin, 2010) Experimental setup wwnick, Austin, J. (2010) 'Trilateration using 3 latitude and longitude points, and 3 distances', Geographic Information Systems Stack Exchange [Online]. 26/6/2012. Available at http://gis.stackexchange.com/a/415 (Accessed 18/3/2014).
  12. Estimotes x 3 Hardware: D3.2, Software: A1.9 Power: 4 dBm, Interval 200ms Estimote API dated 19/02/2014 Elevation: 210cm (wall) or 240cm (celling) iPad Air Elevation: 130cm (held) or 70cm (on stool) Held flat, home button to left of operator, hands under the device. Technical stuff
  13. Measured power levels (typical) at 1 meter. Receiver iPad Air, home button towards Estimote spot. Typical RSSI values: -65 dBm, -71 dBm, -66 dBm Levels fluctuated approximately ±5 dBM Stayed within this range with other WiFi and Bluetooth devices disabled. Estimote Uniformity
  14. Test ‘lab’ Beacon and reported distance Operator and facing direction Trilateration location
  15. Test ‘lab’ obstructions Mac with WIFI Shelf below beacon Beacon on bookshelf, obstructed to left Window Door Lamp shade WiFi access point Door
  16. Operator Rotation
  17. iPad rotation
  18. No Operator
  19. Rotation of iBeacon Bottom right beacon rotated only, stuck to wall, vertical orientation facing iPad, operator stood in front of iPad, iPad at 70cm elevation on stool.
  20. Rotation of iBeacon Bottom right beacon rotated only, stuck to wall, Horizontal orientation, base facing iPad
  21. Rotation of iBeacon Bottom right beacon rotated only, stuck to celling, horizontal orientation facing iPad, operator stood in front of iPad
  22. Ceiling mounting of Estimotes reduces variance and may also help with blocking by the operator Signal transmission and reception are dependent on the orientation of both the transmitter and receiver. So this should be built into positioning models. Radio absorption by the operator is significant in determining distance. Again models should take account of the direction of the operator. Other radio interference does not seem significant in practice. Recommendations
  23. Does other hardware suffer from the same directionality issues? Improve experimental protocol to eliminate operator issues, and take more accurate measurements. Collect further data on the variation in signal strength, to check for statistical significance of effects observed. Experiment with a predictive model to take observed effects into account. Future research
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