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Cellular Positioning

Cellular Positioning. Shashika Biyanwila Research Engineer. Outline. What is Cellular Positioning Positioning Parameters Feasible Approaches Identified Implementation Some Trial Results Future Approach of the Research. What is cellular positioning ?.

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Cellular Positioning

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  1. Cellular Positioning Shashika BiyanwilaResearch Engineer

  2. Outline • What is Cellular Positioning • Positioning Parameters • Feasible Approaches Identified • Implementation • Some Trial Results • Future Approach of the Research Cellular Positioning

  3. What is cellular positioning ? • Determining the position of a Mobile Station (MS), using location sensitive parameters • Why ???? • To provide Location Based Services… Cellular Positioning

  4. Applications of cellular positioning • Operator services • Billing • Network management • Location based services • Wireless Gaming • Assistance • Roadside assistance • Personal or vehicle emergency • Alarm management • Driving Directions • Tracking • Tracking criminals • Tracking external resources containers etc • Monitoring • Monitoring delivery process • Fleet & freight tracking • Personal Child Security • Mobile Worker management • Information • Traffic • Nearest service • news • navigation help • advertising • Information Directory Cellular Positioning

  5. Positioning Parameters • Cell-ID • Received Signal Strength Intensity (RSSI) • Timing Advance (TA) • Uplink Time (Difference) Of Arrival (TDOA) • Downlink Observed Time Differences (E-OTD) • Angle of Arrival (AOA) Cellular Positioning

  6. Feasible Approaches Identified Cellular Positioning

  7. 1. Geometrical Approach • Based on distance measurements • Two Steps: - Distance calculation - Location Estimation Cellular Positioning

  8. Geometrical approach contd.. • Distance Calculation - Measure the RSSI from neighboring cells - Apply Propagation models to calculate the distance • Propagation Models - Hata Model - Extended Hata Model - Lee’s Model - CCIR Model - Walfisch-Ikegami Model (for micro cells) Cellular Positioning

  9. 2. Statistical Approach • Construct a statistical propagation model for the RSSI • Find RSSI at distance d from the transmitter • Offsite calibration is necessary to estimate the propagation parameters • Define a probability distribution for the RSSI • Location estimation problem is solved as an inverse or, rather, inference problem Cellular Positioning

  10. Statistical Approach contd.. • Log-loss or Log-distance model • Gaussian Probability Distribution • Propagation Parameter Estimation - Maximum Likelihood estimation • Location Estimation - Maximum A posteriori Probability Cellular Positioning

  11. Statistical Approach cntd.. • Area being considered is divided into several squares • A posterior probability of the location be within a square, is calculated for each square Square with Maximum A posterior Probability Cellular Positioning

  12. 3. Database correlation Method (DCM) • Involves a database of reference fingerprints for the whole area of interest. • Fingerprint – a recorded measurement sample from a certain location in the area GPS coordinates of a location RSSI (from available cells) in that location Cellular Positioning

  13. Fingerprint Measurement Fingerprint Test route DCM contd… • How to collect fingerprints? • By measurements • Using a Network planning tool • High sampling resolution is needed. Cellular Positioning

  14. Input Measurement DCM Algorithm Estimated Location Database DCM contd… • Location estimation • Compare the input measurement with reference fingerprints • - Using Cost Functions • Location of the best matching reference fingerprint • Estimated Location Cellular Positioning

  15. RSS RSSI + GPS Reading Location ? Measurement Unit Commands • Interfacing Program • Database • Location Estimation Algorithm • Display Program • Software environment Implementation Hardware Environment Cellular Positioning

  16. Urban - Wellawaththa to Kolpetty Suburban - Katubedda to Piliyandala Rural - Ibbagamuwa Trial & Results Cellular Positioning

  17. Urban area….. Cellular Positioning

  18. Suburban area ………. Cellular Positioning

  19. Rural area …….. Cellular Positioning

  20. Future Approach of the Research • Improvements to the current DCM approach • Drawbacks - Few instances of poor estimations - Creating, updating & maintenance of the database • How To Overcome - Refined estimation techniques - Use of a Network planning tool to create fingerprints Cellular Positioning

  21. GSM Network Received Signal Fingerprint Estimated Location • System Information • Calibration Fingerprints • Digital Maps Location Estimation using Received Signal Fingerprint & database Positioning Engine • Implementation of a positioning engine and associated services Services • Get your own location • Track others – web-based location on a map Cellular Positioning

  22. Thank You

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