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

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 [[email protected]], [Vern Brethour] Company [Time Domain] E-mail [[email protected]], Uri Kareev Company [Pulsicom Technologies], E-mail [[email protected]]

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.

January 2003

DTC – TDC - Pulsicom, Aiello - Brethour - KareevSlide 2

doc.: IEEE 802.15-03/050r1

Submission

UWB: a solution for location awareness in TG4 applications

Roberto Aiello ([email protected])

Discrete Time Communications

Vern Brethour([email protected])

Time Domain

Uri Kareev ([email protected])

Pulsicom Technologies

January 2003


doc.: IEEE 802.15-03/050r1

Submission

Summary

• TG4 applications that require location awareness• Requirements • Methods of location estimation• Time of arrival measurements• Relevant issues

January 2003


doc.: IEEE 802.15-03/050r1

Submission

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.)

January 2003


doc.: IEEE 802.15-03/050r1

Submission

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

January 2003


doc.: IEEE 802.15-03/050r1

Submission

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

January 2003


doc.: IEEE 802.15-03/050r1

Submission

Location measurement with time of arrival

• 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

t0

RX1RX2

RX3 RX4

TX

t1

t3

t2

t4

d1 d2

d3

d4

January 2003


doc.: IEEE 802.15-03/050r1

Submission

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

January 2003


doc.: IEEE 802.15-03/050r1

Submission

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

January 2003


doc.: IEEE 802.15-03/050r1

Submission

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

-5000 -4000 -3000 -2000 -1000 0 1000 2000 3000 4000 5000 6000 7000

X-Y

X-Z Y-Z

X

Y

Z

Example of location measurements (units in mm)

January 2003


doc.: IEEE 802.15-03/050r1

Submission

Office trial (units in m)

January 2003


doc.: IEEE 802.15-03/050r1

Submission

UWB advantages

• High accuracy (proportional to bandwidth)• Robust to multipath and to interference• Low power consumption• Leads to low cost implementation

January 2003


doc.: IEEE 802.15-03/050r1

Submission

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

January 2003


doc.: IEEE 802.15-03/050r1

Submission

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

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

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