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Precision Geolocation in Challenging Environments

This tutorial addresses improving geo-location range and accuracy in challenging environments. Learn about location techniques for various use cases like rural, urban, and integrated positioning systems. Discover solutions for signal propagation and multipath mitigation.

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Precision Geolocation in Challenging Environments

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  1. Precision Geolocation in Challenging Environments Authors: Abstract This tutorial is for the IEEE 802 Plenary session on July 2011 in San Francisco The presentation describes how location techniques can improve the proposed geo-location range and accuracy for determining location in challenging environments. Notice: This Document has been prepared to assist the IEEE P802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.22. Russ Markhovsky, InvisiTrack, Inc.

  2. Possible Use Cases Russ Markhovsky, InvisiTrack, Inc.

  3. Rural Geo-Location BS 30 km Backhaul CPE CPE CPE July 2011 Slide 3 Russ Markhovsky, InvisiTrack, Inc.

  4. Outdoor Geo-Location July 2011 • Geo-Locate over long distances • Needs either multiple Base Stations … • or a Base Station and a number of reference CPEs for which the latitude and longitude are known Slide 4 Russ Markhovsky, InvisiTrack, Inc.

  5. Urban Corridor and Indoor Geo-Location July 2011 • Geo-Locate over shorter distances • Needs to operate in harsh multipath environment • Either a terminal (nomadic CPE) or base station/ fixed CPE originates the ranging signal Slide 5 Russ Markhovsky, InvisiTrack, Inc.

  6. Multiple Use Cases SALES & MARKETING Location-aware Advertising Social Networking Social Gaming LBS / ASSET TRACKING Warehouses Disaster Recovery Equipment & Supplies PUBLIC SAFETY/MILITARY Locate/Track Personnel Search & Rescue Monitor Military Campaigns Russ Markhovsky, InvisiTrack, Inc.

  7. Integrated (Hybrid Positioning Enhancement) GPS A-GPS Cell-ID ISM BANDS TVWS BANDS 50 meters 3 meters 300 meters 100 meters 6 meters 400 meters 150 meters Russ Markhovsky, InvisiTrack, Inc.

  8. Defining Core Problem Russ Markhovsky, InvisiTrack, Inc.

  9. Signal Propagation - Background • Signal penetration in dielectric • Loss varies as square root of wavelength • Lower frequencies penetrate better than higher • Example: with the same loss, 240 MHz penetrates 3.2 times further than 2.4 GHz or, at same distance, loss at 2.4 GHz is 10 dB greater. • Dispersion (multipath): inversely proportional to wavelength • Objects smaller than the wavelength don’t reflect; • Objects larger than the wavelength, reflect and generate multipath dispersion. Russ Markhovsky, InvisiTrack, Inc.

  10. White Spaces Superior Platform for Location Obstacle: Metal Beam High 5.6 GHz (UWB) 2.4 GHz Frequency Spectrum 900 MHz Ideal for Terrestrial Geolocation 512 MHz Low The lower the frequency, the greater the ability to penetrate buildings and thereby improve location positioning accuracy and reliability. Russ Markhovsky, InvisiTrack, Inc.

  11. Proposed Solutions Russ Markhovsky, InvisiTrack, Inc.

  12. How do you deal with complex environment location? • With the required +/- 15 m ranging accuracy, once impact of SNR and other imperfections are taken into account, there is little room left for the actual ranging errors that are associated with ranging in a dense multipath environment in buildings/ urban corridors where multipath echoes are closely spaced • Multipath Mitigation • Real-time ranging signal (terrestrial positioning signal) processing algorithm (method) that mitigates multipath and delivers high accuracy using < 6 MHz of bandwidth Russ Markhovsky, InvisiTrack, Inc.

  13. Multipath Mitigation Russ Markhovsky, InvisiTrack, Inc.

  14. Multipath Mitigation Overview • Can be easily incorporated into OFDM based wireless networks, • Employs existing wireless network signals • Reference and/ or pilot signals, etc. • No changes to HW and OS • Developed for indoor and challenging outdoor environments • Dense multipath environment • Low computational intensity multipath mitigation algorithms • Can be executed in software by a mobile terminal • Developed for fixed and mobile environment • Allows simultaneous tracking of hundreds terminals Russ Markhovsky, InvisiTrack, Inc.

  15. Solution Integration • Geolocation ranging signal is < 6 MHz BW(i.e., does not require channel bonding). • The ranging signal consists of: • Pilot signals or subcarrier signals; or • A combination of pilots and subcarriers; • The ranging signal subcarriers do not need to be modulated; the modulation may also be applied, for example QPSK, as long as the modulation signal is known beforehand. Russ Markhovsky, InvisiTrack, Inc.

  16. Multipath Mitigation Processor • Maps time delay to phase offset – resulting in observables sums of complex sinusoids; • Uses optimized high-resolution spectrum estimation analysis methods and techniques; • Algorithms designed to separate direct path for Accurate range estimation • Methods and techniques support frequency estimations (delays) that approach the Cramer-Rao Bound (CRB). Russ Markhovsky, InvisiTrack, Inc.

  17. Solution Integration New option for 802.22 Geo-location model Current 802.22 Geo-location model • Can be seamlessly integrated into the current 802.22 geolocation model – uses complex channel impulse response in the frequency domain Signal Noise Multipath Processor Russ Markhovsky, InvisiTrack, Inc.

  18. Ranging Modes Russ Markhovsky, InvisiTrack, Inc.

  19. One-way and Two-way mode ranging

  20. Test Results July 2011 Slide 20 Russ Markhovsky, InvisiTrack, Inc.

  21. Geo-location Results • Developed portable, battery-operated proof of concept: • Dimensions: 3x4x2 inches • Operating frequencies: VHF (High-band) • Operating bandwidth: 5 MHz • In all tests TX and RX antennas heights were between 0.5 meter to 1.5 meters from the ground . Russ Markhovsky, InvisiTrack, Inc.

  22. Geolocation Results Russ Markhovsky, InvisiTrack, Inc.

  23. UMBC Field Amplitude Estimate Phase Estimate Russ Markhovsky, InvisiTrack, Inc.

  24. Conversion to Distance Russ Markhovsky, InvisiTrack, Inc.

  25. UMBC Field Russ Markhovsky, InvisiTrack, Inc.

  26. UMBC Engineering Russ Markhovsky, InvisiTrack, Inc.

  27. Conversion to Distance Russ Markhovsky, InvisiTrack, Inc.

  28. Result Russ Markhovsky, InvisiTrack, Inc.

  29. Additional Test Results Russ Markhovsky, InvisiTrack, Inc.

  30. UMBC Parking Garage Russ Markhovsky, InvisiTrack, Inc.

  31. Conversion To Distance Russ Markhovsky, InvisiTrack, Inc.

  32. Result Russ Markhovsky, InvisiTrack, Inc.

  33. UMBC Commons Russ Markhovsky, InvisiTrack, Inc.

  34. UMBC Engineering (Example 2) Russ Markhovsky, InvisiTrack, Inc.

  35. Conversion to Distance Russ Markhovsky, InvisiTrack, Inc.

  36. Results Russ Markhovsky, InvisiTrack, Inc.

  37. UMBC Parking Garage (Example 2) Russ Markhovsky, InvisiTrack, Inc.

  38. Conversion to Distance Russ Markhovsky, InvisiTrack, Inc.

  39. Result Russ Markhovsky, InvisiTrack, Inc.

  40. Backup Slides Russ Markhovsky, InvisiTrack, Inc.

  41. Geolocation accuracy vs fine ranging accuracy • For a given geolocation error, the ranging error has to be smaller because geolocation methods/ techniques can be subject to location geometry degradation. Good Geometry Trilateration Triangulation Assuming that the geometry degradation amplification is 2X (on average), the required ranging accuracy is +/- 25 meters. • In addition, the network device electronics propagation delays (residual delay) accuracy is assumend to be +/- 30 ns. This results in +/- 10 meters ranging error • In 802.22, this residual delay needs to be measured by the manufacturer with an accuracy ofat least +/-30 ns (IEEE Std 802.22-2011, subclause 7.7.7.3.4.10.) • Thus the required fine ranging accuracy needs to be +/- 15 meters Bad Geometry Gerald Chouinard, Russ Markvosky

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