Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS) Submission Title: [UWB: a solution for location awareness in TG4 applications] Date Submitted: [January 2003] Revised: [14 January 2002] Source: [Roberto Aiello] Company [Discrete Time Communications] E-mail [Roberto@DiscreteTime.com], [Vern Brethour] Company [Time Domain] E-mail [vern.brethour@timedomain.com], Uri Kareev Company [Pulsicom Technologies], E-mail [kareev@pulsicom.com] Re: [UWB for location awareness] Abstract: [This presentation is an introduction to UWB for location awareness for TG4 applications.] Purpose: [Tutorial contribution] Notice:This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual or organization. The material in this document is subject to change in form and content after further study. The contributor reserves 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 P802.15.

2. UWB: a solution for location awareness in TG4 applications Roberto Aiello (Roberto@DiscreteTime.com) Discrete Time Communications Vern Brethour(Vern.Brethour@TimeDomain.com) Time Domain Uri Kareev (kareev@pulsicom.com) Pulsicom Technologies DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

3. Summary • TG4 applications that require location awareness • Requirements • Methods of location estimation • Time of arrival measurements • Relevant issues DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

4. Application examples • Building automation (ease of installation and maintenance) • Home automation • Inventory (hospital, warehouses, file tracking, etc.) • People tracking (resource optimization in offices), optimize efficiency/security in factories, etc.) DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

5. Location relevant requirements • No mobility or low speed requirement • Relatively fast response time for tracking • Centimeters to meters resolution and accuracy • Low power (long battery lifetime) • Low cost DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

6. Methods for location awareness • Fixed infrastructure • Access points synchronization • Inverse GPS triangulation • Ad hoc network • No engineered access points • Only relative distances between nodes are known • Ad hoc network with fixed references • Some network nodes fix location and provide reference • 2 references to fix in 2D, 3 references to fix in 3D DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

7. Location measurement with time of arrival t0 TX d1 t1 d2 RX1 • Time of arrival • TX sends UWB signal at time t0 • RX1receives UWB signal at time t1 • RX2 receives UWB signal at time t2 • Absolute time of arrival • Calculate distance d1 = (TX-RX1) = (t1 – t0)*c • Estimate location with distances • Requires clock synchronization between access points and nodes • Relative time of arrival (differential) • Calculate distance difference (d1-d2) = [(t1-t0)-(t2-t0)]*c = (t1-t2)*c • No need for synchronization with the node • Estimate location with curves intercepts • Requires clock synchronization between access points RX2 d3 t2 d4 t3 t4 RX4 RX3 DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

8. Time of arrival characteristics • Line-Of-Sight • Time of arrival = distance • Resolution inversely proportional to risetime (proportional to bandwidth) • UWB works well for time of arrival measurement • Non-Line-Of-Sight • Always catch the earliest path • Additional error caused by difference between shortest radio path and direct path) • Additional error gets better with information from multiple nodes and additional algorithms DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

9. Time of arrival performance • UWB • 10 centimeters accuracy in LOS with minimum processing • Few centimeters accuracy achievable in NLOS with post-processing algorithms • Narrowband (ISM or U-NII) • 3m accuracy in LOS with minimum processing • Few meters in accuracy achievable in NLOS with post-processing algorithms • Location awareness advantages • No location information -> go look for the object • Location information (narrowband) -> go find the object • Location information (UWB) -> go get the object DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

10. Example of location measurements (units in mm) DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

11. Office trial (units in m) DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

12. UWB advantages • High accuracy (proportional to bandwidth) • Robust to multipath and to interference • Low power consumption • Leads to low cost implementation DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

13. Other issues relevant to TG4 • Communication and location potentially require processing different paths • Communication and location are probably separate functions • Most of location function is PHY related -> no MAC modifications required DTC – TDC - Pulsicom, Aiello - Brethour - Kareev

14. Conclusions • UWB is a natural technology for location awareness • Provides additional feature beyond a “communications only” platform • UWB works in multipath environments where narrow band approaches are challenged DTC – TDC - Pulsicom, Aiello - Brethour - Kareev