overview of localisation technologies - ask-it by radio frequency transmission ability: •...

Overview of Localisation Technologies

ASK-IT for Technical Providers

13th October 2005 - Stuttgart

Richard [email protected]

School of Civil Engineering & GeosciencesPGR Centre, Cassie Building,

University of Newcastle upon Tyne,NE1 7RU, England

With RFID/Smartdust and Galileo

Contents

• ASK-IT Outline• Technology in context• Satellite technologies• RFID• Smartdust• Mobile phone based technologies• Wireless network based technologies• Summary• Conclusion

ASK-IT Outline

• …to provide personalised, configurable, intuitive and context-related applications and services. These will be derived from a number of sources and will be made available via a web-based system serving a variety of fixed and mobile devices.’(ASK-IT Outline)

Contents

ASK-IT OutlineTechnology in contextSatellite technologies

RFIDSmartdust

Mobile phone based technologiesWireless network based technologies

SummaryConclusion

Technology in context

• Need to match localisation technology with user location and profile

• Must appreciate limitations of technologies• Redundancy• Why?

– GPS in a multi level indoor shopping centre– Wireless networking in large open areas

Context: User location

• Outdoors– Dense urban – cities– Low density urban – suburbs– Open areas – recreation grounds, tourist

areas

Context: User location

• Indoors– Shopping centres– Sports centres– Transport interchanges– Hotel / Restaurant / Bar / Other leisure

Context: User profile

• Pedestrian– Weight– Power– Portability– Discreteness– Compatibility

Smartphone PDA

Context: User profile

PDA in-car

Full in-car solution

• Transport user– Integration– Power– Display– Private / Public

Contents


RFIDSmartdust


SummaryConclusion

Satellite Technologies

• Galileo• GPS• Differential

Corrections• EGNOS• SISNeT

GPS Satellite

Galileo – basic facts

• European GPS• 30 satellites• 27 active + 3 spare• 10 SVs in 3 orbits• Altitude of 23 222 km• Operational: 2010

Image: ESA, J. Huart

Galileo constellation

Galileo Launch Schedule• Currently lab testing• Galileo test bed satellite

launch end 2005• Test campaign for 2.5

years• Secure Galileo

frequencies• Atomic clock

characterisation• Test signals broadcast• Operating environment

surveyedImage: ESA

Galileo Constellation Population

• Launch by Ariane 5• Europe’s heavy

launcher• Up to 10 tonnes

payload mass• Capable of holding 8

Galileo satellites

Payload of 8 Galileo satellitesImage: Astrium

Galileo Services

• OS two free civil signals

• CS provides added value

• PRS for security agencies

• SoL gives integrity warnings

• SAR for fast rescue operations

• Open Service (OS)• Commercial Service

(CS)• Public Regulated

Service (PRS)• Safety of Life (SoL)• Search & Rescue

(SAR)

Galileo Services

• Free open access service for civilian users.

• Provides position, timing and velocity information

• Two frequencies, support for single frequency users




(SAR)

Galileo Services

• Provides added value• External agencies able to

buy bandwidth• Built on top of OS• Two further frequencies• Data carrier available for

transmission of data such as maps/charts, databases & correction data




(SAR)

Galileo Services

• Devoted to security agencies

• Anti-spoofing and anti-jamming




(SAR)

Galileo Services

• Provides integrity warnings to OS users

• 12 m horizontal• 20 m vertical• 6 seconds time to

alarm• Free service, though

charge for equipment (tbc)




(SAR)

Galileo Services

• Provides added functionality on top of current SARSAT / COSPAS

• Uses data carrier for acknowledgements

• Accurate position at time of alert




(SAR)

Galileo PerformanceOpen Service

Carriers Single Frequency Dual-FrequencyComputesIntegrity

No

Type of ReceiverIonosphericcorrection

Based on simplemodel

Based on dual-frequencymeasurements

Coverage GlobalAccuracy (95%) H: 15 m

V: 35 mH: 4 mV: 8m

Alarm LimitTime-To-Alarm

Integrity

Integrity riskNot Applicable

Continuity Risk 8x10-6/15 sTiming Accuracy wrt UTC/TAI Not defined 50 nsecCertification/Liability No NoAvailability 99 % - 99.9 %

Service Performance for Open Service with the Satellite Navigation Signalsonly and without any other augmentations.

From Forrest, W., 2002

GPS

• GPS and Galileo very similar

• Differences– Galileo two civil

frequencies from start– GPS one civil

frequency, one more in future

– SoL life service not available with GPS (currently)

28 m Vertical accuracy

15 mHorizontal accuracy

95% Confidence

4 mVertical accuracy

2 m Horizontal accuracy

95% Confidence

Ref: users.erols.com

Average GPS accuracy

Average GPS accuracy with differential correction

GNSS Multipath Effects

(Evans, J., 2005)

(Evans, J., 2005)

Differential Corrections

• DGPS, WAAS etc.• Basic theory:• Two receivers, stationary known position and

roving receiver• Stationary receiver works out timing signals from

GNSS coordinates and its known position• Stationary receiver compares real with receivers• Difference is correction factor• Transmitted in local area

Augmentation technologies• EGNOS• European Geostationary

Navigation Overlay Service

• Three satellites• Contains information

about accuracy and reliability plus correctional data

• Allows users to determine position to about 5 meters

• Operational early 2006

• SISNeT• Signal in Space over

internet• Gives access to wide area

differential corrections including EGNOS integrity messages

• Gets over problems that satellites have in urban areas including EGNOS

EGNOS Demonstration

• Used in German round of World Rally Championships in August

• Simultaneous recording of GPS and EGNOS data

• Comparison of positing by displaying GPS and EGNOS position of the car relative to highly accurately surveyed track

EGNOS Demonstration

Satellite Technology for Localisation

• Points to consider:• Outdoor• Large error – block size• Urban canyons• Indoor?• Signals through (wireless)

internet• Compactness of current

devices• Low cost – mature

technology

Contents


RFIDSmartdust


SummaryConclusion

RFID System

• Radio Frequency IDentification• A complete RFID system has three key

components and maybe extended

Image: GAO

RFID System - Tags

• Quite mature technology• Friend of Foe -1939• Comprises of antenna

(wire coil), microchip and is most often stuck to the underside of a label

• Uses:– Security (stock)– Inventory systems– Freight handling

The back (underside) of a typical simple RFID tag

Image: GAO

RFID

Image: kennedy group

RFID Tag Classification

• By power:• Passive

– Not powered• Active

– Has internal battery or connected to an external power source

– Hence greater cost

• By radio frequency transmission ability:

• Passive RF– Can only transmit data

by reflecting incoming electromagnetic waves

• Active RF– Can transmit data by

using internal power source to power aerial and microchip

RFID Tag Classification

• By tag type:• Type I

– Read-only

• Type II– Read/write

• Type II+– As type II but with

enhanced external features

• Type II++– As type II but with

serial connection

• Type III– Read/write plus LCD

display

• Type IV– Read/write as

smartcard

RFID Sytem - Reader• RF passive, non-powered

tags:• Reader initiates

conversation• Reader emits RF energy

that cause a current flow in the antenna and powers the chip

• Reader extracts data from the chip via the antenna and powers off

Proximity smartcard and reader

RFID reader in stock room (www.philips.com)

RFID System - Reader

• Powered, RF active tags:• Reader or tag may initiate

conversation• Tag uses power source to

power microchip and send data via antenna

• Range is larger than RF passive tags

• Read write tags may have new data written e.g. road user charging

Image: www.cs.hku.hk/~clwang/

Image: www.derwinbell.com

State Road-91 Express Lanes (SR91) in Orange County, CA the first totally automated electronic toll collection system in the U.S

RFID Performance Characteristics

10 – 100 tags / s

100 –1000 tags / s

RFID Tags – Size and Costs

• Size: any size, from in car units – smart cards – stock labels –millimetre dimensions

• Cost: average price for passive type I tags around €0,15 - 0,40

• Ultra small in large quantities ˜ €0,05

• More complex tags with long transmission range ˜ €17 ($20)

A 0.25mm2 RFID tagImage: smartcode

RFID Standards

• EPCglobal Class 1 Generation 2 RFID Specification

• Establishes a single UHF specification over several previous ones

• Sets minimum read and write speeds to 500 / 30 tags/sec

RFID for Localisation

• RFID tags in doorways, lifts, shop fronts, breadcrumb trail

• Map database integrated into reader

• Considerations:• Power• Range• Low cost simple tags

Newcastle Smart Sign Project

SmartSignNCLU/0008

www.smartsign.co.uk

Contents


RFIDSmartdust

Cellular phone based technologiesWireless network technologies

SummaryConclusion

Smartdust (motes)• Motes > smartdust• Similar to Class IV

RFID tags• RF active• Powered• Tiny OS• Sensor stack

Images: intel, xbow

Ad Hoc Networks

Smartdust @ Newcastle

• ASTRA project• Smartdust corridor• Network reporting of

bus position• Demonstration of use

for localisation• Various MSc projects

Newcastle Smartdust Corridor

Smartdust for Localisation

• Similar characteristics to RFID

• IEEE802.11.x standards widely used

• Hence better compatibility with existing equipment

• Costs:• Current devices are

not cheap• ˜ €140 for MICA2

mote

• Smartdust costs will be signifcantly lower

Contents


RFIDSmartdust


SummaryConclusion

Mobile phone based technologies

• Cellular mobile phone based

• GSM (TDMA)– Triangulation method gives

horizontal accuracy of 50 –200 meters

• 3G (CDMA)– Smaller sized cells with

greater overlapping accuracy more than that of TDMA networks

– 4G phones will have GPS chips inside to allow the phone to calculate it’s position

Mobile phone based technologies

• Mobile Phone Features• Good in urban areas

where cells overlap• Can be used indoors with

additional network access points e.g. Metrocentrethough leaky coaxial not suitable

• Tend to have good network strength around major road networks

• Limited signal in remote areas

Wireless Networks• Wireless networks• Infrastructure based

– e.g. university network, device can detect range to nearest access points and calculate position

• Mobile ad-hoc– Allows information from

devices with knowledge to pass to other devices and so on e.g. traffic jams

• Bluetooth• Smartdust

Key Issues

1. Technology must be compatible with the users mode of travel and application area

2. Accuracy of localisation signal3. Compatibility with existing equipment4. Unit cost5. Combination & redundancy of

technologies

References and links• Kennedy Group

www.kennedygrp.com• European Space Agency

www.esa.int• SmartCode Corp.

www.smartcodecorp.com• United States

Government Accountability Office www.gao.gov

• EPCglobal Inc. www.epcglobalinc.org

• Intel www.intel-research.net

• Xbow www.xbow.com• Evans, J. 2005, Central

London Congestion Charging Scheme, presentation, October 7th

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