1. doc.: IEEE 802.11-09/1212r0 Submission Nov 2009 Dong Kyoo Kim, ETRISlide 1 Time-based ranging technology for IEEE802.11 Notice: This document has been prepared to assist IEEE 802.11. 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 grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Date: 2009-11-17 Authors:

2. doc.: IEEE 802.11-09/1212r0 Submission Nov 2009 Slide 2 Abstract We talk about IEEE802.11 enhancement for ranging measurement. –WLAN Localization –General WLAN System architecture –Problems –Accurate measurement of time delay –Experiment –Conclusion Dong Kyoo Kim, ETRI

3. doc.: IEEE 802.11-09/1212r0 Submission WLAN Localization Many RSS-based methods RTT-based methods 1.Measurement at 1 usec resolution 2.Measurement at 22.7 nsec resolution Andre et al, “Measureing round trip times to determine the distance between WLAN nodes,” IFIP2005 Fernan et al, Performance evaluation of a TOA-based trilateration method to locate terminals in WLAN, 2006 Nov 2009 Dong Kyoo Kim, ETRI 1000 samples

4. doc.: IEEE 802.11-09/1212r0 Submission General WLAN System Architecture TSF Timer accuracy : 100ppm ‘MAC – Buffer – PHY’ Architecture causes uncertain delay. PHY System Bus PHY Interface DMA TX BUF RX BUF Control TSF Timer RPC MAC H/W TX Crd RX Crd MPDU Other Blocks Interface 8-bit TX 8-bit RX 10MHz Interface Nov 2009 Dong Kyoo Kim, ETRI +-25 ppm

5. doc.: IEEE 802.11-09/1212r0 Submission Problems Do the legacy devices response with the fixed time? Time variation of several hundreds of nanoseconds gives ranging error of over 100 meters. It is said that the current WLAN is inappropriate for a ranging device. Nov 2009 Dong Kyoo Kim, ETRI

6. doc.: IEEE 802.11-09/1212r0 Submission Accurate measurement of Time delay? For the accurate time-delay measurement, accurate and consistent response time is required. The existing MAC-layer response mechanisms such as CTS response and ACK response have the performance limit due to the implementation architecture. Nov 2009 Dong Kyoo Kim, ETRI

7. doc.: IEEE 802.11-09/1212r0 Submission Experimental Setup Round-trip-time is measured using 80MHz counter Measurements are performed 50000 times Sep 2009 Hitoshi MORIOKA, ROOT Inc.Slide 7 WLAN AP (11g) RTT Measurement Module

8. doc.: IEEE 802.11-09/1212r0 Submission Experimental results The following figure shows that the RTT is varied from 6605 to 6634 From 6609 to 6624, it is almost uniform (187.5nsec) Nov 2009 Dong Kyoo Kim, ETRI X-axis: RTT counter value Y-axis: Occurrence

9. doc.: IEEE 802.11-09/1212r0 Submission Conclusion We have a plan to test about the RTT-based ranging performance. We also have a plan to test several PHY-layer ranging methods by using our measurement module, and report test results in the next session. Sep 2009 Hitoshi MORIOKA, ROOT Inc.Slide 9

10. doc.: IEEE 802.11-09/1212r0 Submission Nov 2009 Slide 10 Questions & Comments Dong Kyoo Kim, ETRI

11. doc.: IEEE 802.11-09/1212r0 Submission Nov 2009 Slide 11 Straw Poll “Should IEEE802.11 WNG receive further presentations analyzing the WLAN-based ranging technology?” Yes: No: Need More Discussion: Don’t Care: Dong Kyoo Kim, ETRI