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CSI 5169 --- Wireless Networks and Mobile Computing Indoor Localization

CSI 5169 --- Wireless Networks and Mobile Computing Indoor Localization. Zhang Zhang zhangzhang@uottawa.ca. Outline. Introduction Definition Important parameters Indoor Localization Methods Proximity Detection Triangulation Scene Analysis Indoor Localization Systems Proximity Based

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CSI 5169 --- Wireless Networks and Mobile Computing Indoor Localization

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  1. CSI 5169 --- Wireless Networks and Mobile Computing Indoor Localization Zhang Zhang zhangzhang@uottawa.ca

  2. Outline • Introduction • Definition • Important parameters • Indoor Localization Methods • Proximity Detection • Triangulation • Scene Analysis • Indoor Localization Systems • Proximity Based • RF Based • Cameras Based • Comparison of Common Indoor Localization Systems

  3. Introduction - Defination • Def. Wirelessly locate objects or people inside a building in real time. • Indoor Positioning Systems (IPS) • Real-time Locating Systems (RTLS)

  4. Introduction - Important Parameters • Accuracy • Coverage • Availability • Update Rate • Line of Sight (LoS) and Non Line of Sight (NLoS) • Costs and System Complexity

  5. Introduction - LoS / NLoS • Line of Sight (LoS) and Non Line of Sight (NLoS)

  6. Indoor Localization Methods / Algorithm

  7. Methods / Algorithm - Proximity / Cell of Origan • Proximity Detection: Sensors detect and measure reflected Infrared or • visiable light or RF wave to detect the presence of • an object or person in certain areas. • Highest Received Signal Strength = Highest Probability

  8. Methods / Algorithm - Proximity / Cell of Origan • Advantages • No complicated algorithms • Easy to implement • Low cost • Disadvantages • Low accuracy - room level • Identification problem

  9. Methods / Algorithm - Time based • ToA: Time of Arrival • The precise measurement of the arrival time of a signal transmitted • from a mobile device to several receiving sensors. • The distance between the mobile device and each receiving sensor • can be determined.

  10. Methods / Algorithm - Time based - ToA • Advantages • High Accuracy • 2D / 3D • Disadvantages • Precise time synchronization (1 micro-second, 300m error) • Solutions are typically challenged in environments where a • large amount of multipath or interference may exist.

  11. Methods / Algorithm - Time based - TDoA • TDoA: Time Difference of Arrival • Using relative Arrival time measurements at each receiving sensor • The synchronization between tag and each sensor is not necessary • Example: • TXC - TXA = 10-8s • TDoAC_A • TXB - TXA = 10-7s • TDoAB_A

  12. Methods / Algorithm - Angle based - AoA • AoA/DoA: Angle of Arrival / Direction of Arrival (DoA) • Determining the angle of incidence at which signals arrive at the receiving sensor.

  13. Methods / Algorithm - Angle based - AoA • More sensors = Higher accuracy

  14. Methods / Algorithm - Angle based - AoA • Advantages • No synchronization requirement • Works well in situations with direct line of sight • Disadvantages • Susceptibility to multipath interference

  15. Methods / Algorithm - Signal Property Based Signal attenuation can be exploited for distance estimation.

  16. Methods / Algorithm - Signal Property Based RSS: Based on the attenuation model, the Received Signal Strength can be used to estimate the distanced of a person or a mobile object. • PR: Received signal strength at the receiver • PT: Transmitted power strength at the emitter • GT GR: Antenna gains of transmitter and receiver • d: Distance • P: The path loss factor

  17. Methods / Algorithm - Signal Property Based The path loss factor (P) is related to the environmental conditions • P = 2 for free space • P > 2 for environments with NLoS multipath • P ≈ (4 - 6) for typical indoor environments In real world application, interference, multipath propagation and presence of obstacles and people leads to a complex spatial distribution of RSS. RSS Indicator (RSSI): averaged PR over a certain sampling period

  18. Methods / Algorithm - Fingerprinting Off-Line

  19. Methods / Algorithm - Fingerprinting M(-35, -50, -48, -60, -58,-24) vs. Database

  20. Methods / Algorithm - Fingerprinting • Advantages • High accuracy • NLoS • Disadvantages • Complicated algorithms • Not easy to implement • High cost

  21. Indoor Localization Systems

  22. Indoor Localization Systems - WIFI WIFI: (a superset of IEEE 802.11 standard) can be used to estimate the location of a mobile device within this network.

  23. Indoor Localization Systems - RFID • RFID (Radio Frequency IDentification) system consists of readers with antennas which interrogates nearby active transceivers or passive tags.

  24. Indoor Localization Systems - ZigBee • ZigBee is a wireless technology particularly designed for applications which demand low power consumption and low data transmission.

  25. Indoor Localization Systems - Cameras • Images → Cameras • Cameras → Database • Database → Virtual Map

  26. References • [1] Z. Farid, R. Nordin, and M. Ismail, "Recent Advances in Wireless Indoor Localization Techniques and Systems," Journal of Computer Networks and Communications, vol. 2013, 2013. • [2] R. Mautz, "Indoor positioning technologies," Habilitation Thesis, Department of Civil, Environmental and Geomatic Engineering, Institute of Geodesy and Photogrammetry, Habil. ETH Zürich, Zurich, 2012. • [3] H. Koyuncu and S. H. Yang, "A survey of indoor positioning and object locating systems," IJCSNS International Journal of Computer Science and Network Security, vol. 10, pp. 121-128, 2010. • [4] A. Aboodi andW. Tat-Chee, “Evaluation ofWiFi-based indoor (WBI) positioning algorithm,” in Proceedings of the 3rd FTRA International Conference on Mobile, Ubiquitous, and Intelligent Computing (MUSIC ’12), pp. 260–264, June 2012. • [5] S. Chan and G. Sohn, ¡°Indoor localization using Wi-Fi based fingerprinting and trilateration techiques for LBS applications,¡± in Proceedings of the 7th International Conference on 3D Geoinformation, Quebec, Canada, May 2012.

  27. 1 5 5 3 2 2 1 1 1 2 1 2 3 1 3 3 3 4 1 1 1 1 2 3 4 2 2 5 3 3 Question 1 • The RSSI pattern is shown below. • 3 Wifi routers • 9 refernces points • Q: Where is M(1.2, 2.6, 4.5) in this pattern?

  28. 1 5 5 3 2 2 1 1 1 2 1 2 3 1 3 3 3 4 1 1 1 1 2 3 4 2 2 5 3 3 Question 1 Q: Where is M(1.2, 2.6, 4.5) in this pattern? A: Measured RSSI of Wifi one is 1.2. Red zone (referenced RSSI of Wifi one is 1) are possible locations.

  29. 1 5 5 3 2 2 1 1 1 2 1 2 3 1 3 3 3 4 1 1 1 1 2 3 4 2 2 5 3 3 Question 1 Q: Where is M(1.2, 2.6, 4.5) in this pattern? A: Measured RSSI of Wifi two is 2.6. Green zone(referenced RSSI of Wifi two is 3) are possible locations.

  30. 1 5 5 3 2 2 1 1 1 2 1 2 3 1 3 3 3 4 1 1 1 1 2 3 4 2 2 5 3 3 Question 1 Q: Where is M(1.2, 2.6, 4.5) in this pattern? A: Measured RSSI of Wifi three is 4.5. Blue zone(referenced RSSI of Wifi two is 5) are possible locations. The intersection of three zones is the location of M.

  31. 1 5 5 3 2 2 1 1 1 2 1 2 3 1 3 3 3 4 1 1 1 1 2 3 4 2 2 5 3 3 Question 2 • The RSSI pattern is shown above. • 3 Wifi routers • 9 refernces points • Q: Where is M(5, 2, 1) in this pattern? • Is there any methods to increase the acceracy by optimizeing the system?

  32. 1 1 2 3 4 2 4 Question 2 • Q: Is there any methods to increase the acceracy of this system? • A: More Wifi routers, more reference points.

  33. Question 3 • A company with 3 buildings. • Building A: Working Office (Wifi coverd) • Building B: Assembly lines • Building C: Warehouse • Q: Building A: Locating persons + high rate data transmission • Building B: Accurate positioning products + no data transmission • Building C: Locating forklifts + low rate data transmission • Which indoor localization system will you choose for Building A, Building B, • Building C, respectively? why?

  34. Question 3 • A company with 3 buildings. • Building A: Working Office (Wifi coverd) • Building B: Assembly lines • Building C: Warehouse • Q: Building A: Locating persons + high rate data transmission • Building B: Accurate positioning products + no data transmission • Building C: Locating forklifts + low rate data transmission • Which indoor localization system will you choose for Building A, Building B, • Building C, respectively? why? • Answers: • A: WIFI. Wife covered, high data rate, mobile phone. • B: RFID(Passive). Small tag size, high acceracy, low cost. • C: ZigBee. Low power consumption, low cost, low data rate

  35. Thank you!

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