Lecture 1: Overview of Wireless Standards


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Lecture 1: Overview of Wireless Standards

  1. 1. RFID Academic Convocation AUTO-ID Laboratory at MIT CWINS Trends in RF Location Sensing Prepared by: Kaveh Pahlavan, Prof. of ECE and CS and Director CWINS, WPI Presented by: Allan H. Levesque January 23, 2006 ©KP
  2. 2. Outline Evolution of RF Location Sensing Applications – in Commerce – in Military and Public Safety – in other disciplines Localization Research at CWINS/WPI – RSS Localization – Accurate Localization Using TOA January 23, 2006 RFID Research Convocation
  3. 3. Evolution of Localization Industry Problem of locating soldiers carrying mobile radios was first addressed in World War II During the Vietnam conflict US department of defense lunched a series of GPS satellites to support military operation In 1990 signals from GPS satellites became accessible to public In 1996 FCC required locating mobile phones with in 100 meters in 67% of locations In 1997 urban and indoor geolocation started – Military: SUO/SAS project – Commercial: PinPoint, WearNet In 2000 indoor WiFi localization (Newbury Networks and Ekahau) In 2003 UWB localization for WPANs In 2004 localization for sensor networks In 2005 outdoor WiFi localization as a GPS alternatives – Commercial: WiFi positioning in outdoor areas (Skyhook) – Military: Signals of opportunity for disaster recovery (DARPA) January 23, 2006 RFID Research Convocation
  4. 4. Localization in Commerce January 23, 2006 RFID Research Convocation
  5. 5. Typical Commercial Applications Asset tracking in warehouses and hospitals Dispatching and monitoring support staff Locating elderly persons Locating children in public areas Emergency management in hospitals Invisible fencing of pets Tracking golf balls Locating surgical equipment in operation rooms Guiding visitors in museums Navigating sight impaired persons GPS complement for indoor applications January 23, 2006 RFID Research Convocation
  6. 6. Today Everything is a Terminal! iBook Printer Location Sensors VCR Entertainment / Home Networking Scanner Computer/Communication Appliances/Security Control/Metering PROGRAM January 23, 2006 RFID Research Convocation
  7. 7. Bandwidth (Kbps) (100 Mbps) (10 Mbps) (1 Gbps) (1 Mbps) 1 10 100 1,000 1000,000 100,000 10,000 January 23, 2006 Smart Appliances Utility Metering Security Systems Phone Appliances 802.15.4 WPAN Real Audio MP3 Audio Traditional Games Printing 802.11 WLAN Internet Access Camcorder DV MPEG2 Video Standards and Terminals 3D Games USB Connectors 802.15.3a WPAN Multiple HDTV RFID Research Convocation
  8. 8. Localization Accuracy Mobility E-911 (100 meters 67%) Vehicle Outdoor WiFi Positioning (a few meters indoors) Walk 2G Cellular 3G Fixed Cellular UWB (a few centimeters indoor) WLAN Walk Indoor Fixed/ WPAN Desktop 0.1 1 10 100 1000 Mbps User Bitrate, Datacom services January 23, 2006 RFID Research Convocation
  9. 9. Accurate Localization in Military and Public Safety January 23, 2006 RFID Research Convocation
  10. 10. Typical Applications Navigation for fireman Navigation for policemen Providing situation awareness for soldiers Tracking inmates in prisons Tracking in disaster recovery zones January 23, 2006 RFID Research Convocation
  11. 11. January 23, 2006 RFID Research Convocation
  12. 12. SUO-SAS and Urban Fighting January 23, 2006 RFID Research Convocation
  13. 13. Localization Everywhere Robot in rubble Inside caves Forces inside buildings Urban canyons Unattended ground sensors January 23, 2006 RFID Research Convocation
  14. 14. Using Signals of Opportunity January 23, 2006 RFID Research Convocation
  15. 15. Localization in other Research Areas Location-based handoff Location-based routing in ad hoc networks Location-based authentication and security January 23, 2006 RFID Research Convocation
  16. 16. Localization Research at CWINS/WPI January 23, 2006 RFID Research Convocation
  17. 17. Two Technologies RSS – Simple hardware • Accuracy is not sensitive to multipath and bandwidth • Does not need synchronization • Can work with any existing infrastructure and card which can measure power – For accurate localization • Needs high density of references or long training procedure • Needs more complex and computationally intensive algorithms – Used for WiFi Positioning by Ekahau, Newbury Networks, PanGo, Skyhook. TOA – Suitable for accurate indoor positioning • Only needs a few references • Does not need training – More complex hardware • Accuracy is sensitive to multipath and bandwidth • Needs synchronization of the reference time – Used in GPS, PinPoint, WearNet, 802.15.3 and 4. January 23, 2006 RFID Research Convocation
  18. 18. Two Classes of Algorithms Tx1 d1 Tx2 Distance Based Localization d2 Reference Point Tx x x x x x x x x x x 3 x x x x x x x x x x x x AP4 x x x x AP5 x x x x d3 x x x x x x x x x x Grid Resolution x x x x x x x x x x 100 m AP3 x x x x x x x x x x MH x x x x x x x x x x x x x x AP1 x x x x AP2 x x Pattern Recognition x x x x x x x x x x x x x x x x x x x x 100 m Y X January 23, 2006 RFID Research Convocation
  19. 19. RSS Localization at CWINS Microsoft: Nearest Neighbor algorithm based on signature data collection in a training period. – P. Bahl and V. Padmanabhan, “RADAR: an in-building RF-based user location and tracking system,” IEEE INFOCOM, Israel, March 2000. Ekahau: Uses a statistical algorithms for localization with improved accuracy and reduced training data. – T. Roos, P. Myllymaki, H. Tirri, P. Miskangas, and J. Sievanen, “A Probabilistic Approach to WLAN User Location Estimation,” International Journal of Wireless Information Networks, Vol. 9, No. 3, July 2002. CWINS: Develops a real time laboratory testbed and a framework for comparactive performance evaluation of localization algorithms. – M. Heidari and K. Pahlavan, Performance Evaluation of Indoor Geolocation Systems Using PROPSim Hardware and Ray Tracing Software, IWWAN’04, Oulu, Finland, May 2004. CWINS: Uses channel modeling techniques (Ray Tracing and WiFi channel models) to eliminate the need for training data and improve the performance. – A. Hatami, and Kaveh Pahlavan, " Comparative statistical analysis of indoor positioning using empirical data and indoor radio channel models," Consumer communications and networking conference, 2006. January 23, 2006 RFID Research Convocation
  20. 20. Challenges for TOA Estimation Coverage – Existing knowledge only supports coverage of the total power while in TOA estimation we are keen on the coverage of the DP. We need more measurement and modeling effort to solve this problem. Bandwidth – Common belief: increase in bandwidth increases the resolution therefore UWB is the final solution – Problem: Increase in bandwidth reduces the coverage of the first path, which means UWB is not the ultimate solution for Indoor Geolocation UDP – Errors caused by UDP conditions are very large – Detection of UDP is difficult, so we can not avoid UDPs – If we detect the UDP and avoid, coverage become very small Therefore: we need research in algorithms which operate in UDP conditions and provide good coverage with reasonable bandwidth January 23, 2006 RFID Research Convocation
  21. 21. TOA Research at CWINS Modeling of the behavior of TOA sensors (for NSF) UWB – For high-resolution short distance (for DARPA) Super-resolution algorithms – For signals of opportunity (with NSF and RCI) Diversity Techniques – AOA (with Draper Laboratory) – Space and cooperative location estimation (with IWT) January 23, 2006 RFID Research Convocation
  22. 22. Conclusion Localization is one of the fastest growing industries attracting strong research investments from military and commerce Variety of applications are emerging around RSS and TOA based technologies CWINS is the oldest laboratory working in both RSS and TOA technologies with close ties to commerce and military Localization for RFID applications is one the areas of interest at CWINS for future research January 23, 2006 RFID Research Convocation
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