Installation and Evaluation of RFID Readers on Moving

Vehicles

VANET 2009Eun Kyu Lee, Young Min Yoo, Chan Gook Park,

Minsoo Kim, and Mario Gerla

2

RFID applications◦ RFID-enabled vehicular applications

RFID system◦ RFID read performance

Installation of RFID system on vehicle Road test Conclusion

Agenda

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RFID Applications

www.infoworld.com

Supply Chain & Warehouse

ePassport

4

RFID Applications

www.ti.com

www.ezpass.com

www.wikipedia.org

Human implant

Automatic toll collection

Smart payment

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RFID system review RFID communication

2. Radio Frequency Identification (RFID)

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What is RFID?◦ Identify physical objects

through a radio interface

◦ Identification? Assign ID to each object Bar code, license plate, student ID

How does RFID work?◦ RFID tag + RFID reader + antenna◦ Backscattering coupling (UHF)

Radio Frequency Identification (RFID)

Chip

Antenna

02.3DFEX4.78AF51

EasyToll card #816

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Tag type

Radio frequency range

Radio Frequency Identification (RFID)

www.hitachi.com & www.vicariousconversations.com

Passive tag Active tag

Power No power source Internal battery

Pros Small & cheap (~10cents)Long radio range (~150m) & high performance

Cons Short radio range (~10m)Expensive & limited lifetime

FrequencyHF UHF Microwave

13.56MHz 433.92MHz 860-960MHz 2.45GHz

Range < 60Cm 50~100Cm < 3.5m, <10m 1m

Tag Passive Active Passive/Active Passive/Active

Property- Cheap reader- Short range

- Real-time tracking- Cheapest- Multiple-tag contact

- Sensitive to noise

Contact time Slow --------------------------------- Fast

Robustness(Sensitivity)

Robust --------------------------------- Sensitive

Tag size Big --------------------------------- Small

Application- Library books- Access Control

- Container- Real-time location tracking

- Automatic tolling- Supply chain tracking

- Asset tracking- Forgery avoidance

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Framed slotted Aloha (FSA)

RFID Communication

Slot .. .. .

CW Query CyclePower down

CW Query CyclePower down .. .. ..

A response from one RFID tag

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RFID-enabled Vehicular Applications On-board RFID reader system

3. RFID in Vehicular Applications

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Methodology of data producer/consumer◦ RFID tag

Stores data in memory, which is provided to RFID readers A data producer

◦ RFID reader Obtains RFID data from tags and utilizes it for further programs A data consumer

RFID-enabled Vehicular Applications

Each vehicle is a data producer !!

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Tag on vehicle (data producer)◦ Readers are on the roadside◦ Automatic toll collection◦ Intelligent traffic signal system◦ Electronic license plate◦ Priority lane management

Lane reservation and enforcement

RFID-enabled Vehicular Applications

www.ti.com

Reservation/Enforcement

SystemEnforce

Enforce

ReserveReserve

RFID Reader/Camera

High-Priority Lane

Low-PriorityLanesLane Entrance

AssistanceSystem

cs.rutgers.edu

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Reader on vehicle (data consumer)◦ Tags on the roadside units (road surface, sign post,

direction sign)◦ RFID positioning and Road beacon system (RBS)◦ Lane-level GPS (Donath’06)

RFID tags along each lane contains useful data (e.g., position) Intersection collision avoidance, Enhancement of driver’s situation awareness, Lane by lane incident management

RFID-enabled Vehicular Applications

RFID tag

RFID reader

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Tag/reader on vehicle (data prosumer)◦ Intelligent priority lane management◦ Peer localization

RFID-enabled Vehicular Applications

RFID tag

RFID reader

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Challenges◦ High vehicle speed

Faster than 100Km/h on a freeway

◦ Short communication distance Much less chance of RFID communication

◦ Random mobility of reader Reader position affects performance

significantly than tag placement Random fading effects

On-board RFID Reader System

3m~4m

0.3m

RFID tag

RFID reader

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Motivation◦ Initial deployment of RFID reader/tag is important for

better performance◦ Necessary to measure performance in a real test road

In this work, we◦ Install RFID reader on a vehicle and tags on a road

surface◦ Evaluate RFID read performance in a laboratory

environment◦ Propose antenna diversity and tag multiplicity for

improvement◦ Conduct a road test to study feasibility of the system

On-board RFID Reader System

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Specification of the RFID system RFID performance

◦ RFID read area◦ Read latency◦ RFID read rate

4. Understand RFID Read Rate

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RFID System

RFID Reader

RFID Reader Antenna RFID Tag

Antenna

EEPROM

Data

Energy

RFID Communication

Server

RFID reader

FrequencyRF powerRead distanceModulationRadio access

910~914MHz4w EIRP~5mASKFHSS

RFID reader antenna

AngleGainSize

60°(3dB)6 dBi215x420x55

RFID tagDataData rateMax pause time

64bit256kbps62.5ms

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RFID read area◦ Size and moving speed

RFID Performance

h cm

θ° 68°Side view

h cm

68°

RFID Reader Antenna

RFID Reader Antenna

Front viewRead area

Read area

1X cm

2X cm

For instance, if h=37.5cm and θ=45°, then X1=58.58cm and X2=185.63cm

Speed [km/h]

Computed [ms]

Measured [ms]

10 665 360

20 332 180

30 222 120

40 166 90

50 133 72

60 111 60

70 95 51

80 83 45

90 74 40

100 67 36

RFID read area

Moving speed of RFID area

Measured X2≒100cm (1m)

RFID communication should occur in 1m read area within 36m

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Read latency◦ Time period when one RFID communication occurs◦ Measured 38.39ms on average

Mostly due to the maximum pause time of the tag: 62.5ms

◦ However, RFID read area moves at 36ms > 38.39ms Even 60ms at 60km/h < 62.5ms

RFID read rate

RFID Performance

<- 36ms

38.39ms

# of tags successfully read = -----------------------

total # of tags deployed

High possibility of RFID communication failure

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Experiment setup RFID reader antenna

◦ Height◦ Pitch angle◦ Antenna diversity

RFID tag◦ Yaw angle ◦ Pitch angle◦ Tag multiplicity

Result

Laboratory Experiment

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Target performance◦ 0.5m of read area and 18m of read latency

Height of RFID reader antenna h=30cm◦ Similar performance in h=20~40cm◦ Height of the test vehicle is 30cm

Installation◦ RFID reader antenna & RFID tag

Laboratory Experiment

30°of tag yaw angle and 30°of antenna pitch angle 0.5m

RFID tag

18ms of read latency

RFID reader antenna

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Pitch angle◦ Varying pitch angle of the antennas◦ Measure the read area given 18ms of read latency◦ 30° of pitch angle

RFID Reader Antenna

60°

0°Floor

21cm

70cm

Side view

Pitch angle of antenna Length of read area [cm]

50º40º

73.8972.3854.62

74.40

20º

68.95

30º

60º

21cm

10°20°30°

40°

10º

70º

0º 50.86

65.5866.77

50°

70° of pitch angle

30cm

0°10°

20°30°40°50

°60°70°

RFID Reader Antenna

RFID tags are attached on the floor with 0°

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Antenna diversity◦ Install one and dual antenna(s)◦ Measure the read area given 18ms of read latency

RFID Reader Antenna

RFID Tag

RFID Reader Antenna

43 cm

80 c

m

78 c

m

RFID Reader Antenna 1

RFID Reader Antenna 2

65 cm

3m2m

1.5m

1 Antenna

RFID Tag

2 Antennas

0.86m

1.3m

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Yaw angle and pitch angle◦ Measure the read latency given 0.5m of the read area◦ Both are set 0°

RFID Tag

RFID Reader

Antenna

Yaw angle (front view)

Yaw angle

RFID Tag

Floor

30cm

Pitch angle

Pitch angle (side view)

-20 -15 -10 0 10 20 30 40 50 60 70 800

10

20

30

40

50

60

70pitch 0 deg

pitch 10 deg

pitch 20 deg

Distance from the center of reader antenna to a tag [cm]

Ave

rage

rea

d la

tenc

y [m

s]

Yaw angle 0° 30° 60° 90° 120° 150° 180°

Read latenc

y44.3 44.2 x x x 45.1 46.9

30° of reader antenna

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Tag multiplicity◦ To mitigate effect of the random pause time◦ Measure the read latency given 0.5m of the read area◦ Cluster model 3 having 3 or 4 member tags

RFID Tag

Cluster 1 Cluster 2 Cluster 3 Cluster 4

1 2 3 4 510

15

20

25

30

35

40Cluster 1 Cluster 2Cluster 3 Cluster 4

Number of RFID member tags in a cluster

Ave

rage

rea

d la

tenc

y [m

s]

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RFID communication successfully occurs within 0.8m of RFID read area and 18ms of read latency

Antenna diversity and tag multiplicity◦ Showed improved performance

Estimation of the maximum vehicle speed◦ At which RFID communication can occur◦ 161.7km/h◦ Equivalent to previous researches

Results

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Test road configuration Effect of antenna diversity Effect of tag multiplicity

Road Test

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Test Road

RFID Tag RFID Reader Antenna

RFID Reader

Server

Deployment parametersTest1 Test2 Test3 Test4 Test5 Test6

# of antenna 1 2 2 2 2 2

# of member tags 1 1 3 4 3 4

RFID tag interval 2m 2m 2m 2m 5m 5m

Maximum speed [km/h] ~100 ~80 ~80 ~80 ~80 ~100

Test scenarios with variables

RFID reader antenna

RFID tag

Number 1 or 2 Yaw 0°

Height 30cm Pitch 0°

Pitch 30° Member tags 1, 3, or 4

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Effect of antenna diversity◦ Proof of concept in terms of width◦ Reduced length does not affect performance much

Road Test

Average duplication read

Average read rate

10 20 30 40 50 60 70 80 90 1000

20

40

60

80

100 Single RFID reader antenna

Dual RFID reader antenna

Ave

rage

rea

d ra

te [

%]

Vehicle speed [km/h]

10 20 30 40 50 60 70 80 90 1000

2

4

6

8

10 Single RFID reader antenna

Dual RFID reader antenna

Ave

rage

dup

lica

tion

re

ad [

num

ber]

Vehicle speed [km/h]3m

2m

1.5m

1 Antenna

RFID Tag

2 Antennas

0.86m

1.3m

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Effect of tag multiplicity◦ Tag cluster outperforms single tag (Test 2, 3, and 4)◦ Tag interval influences performance (Test 3 and 5)

In particular, at high speed

◦ Duplication read dramatically decreases at high speed

Road Test

10 20 30 40 50 60 70 80 90 1000

5

10

15

20

25

30

Vehicle Speed [km/h]

Ave

rage

Dup

lica

tion

Rea

d [n

umbe

r]

Average duplication read

4 Tags, 5m Interval (Test 6)

1 Tag, 2m Interval (Test 2)3 Tags, 2m Interval (Test 3)4 Tags, 2m Interval (Test 4)3 Tags, 5m Interval (Test 5)

10 20 30 40 50 60 70 80 90 1000

10

20

30

40

50

60

70

80

90

100

Vehicle Speed [km/h]

Ave

rage

Rea

d R

ate

[%]

Average read rate

4 Tags, 5m Interval (Test 6)

1 Tag, 2m Interval (Test 2)3 Tags, 2m Interval (Test 3)4 Tags, 2m Interval (Test 4)3 Tags, 5m Interval (Test 5)

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Summary◦ RFID-enabled vehicular applications◦ On-board RFID reader system◦ Experiment

In a laboratory RFID reader antenna and RFID tag

On a test road

Contribution◦ A different approach to RFID-enabled vehicular system◦ Address antenna diversity and tag multiplicity

The newest topics for performance improvement

◦ Experiment data from a real test bed

Conclusion

Thank you

VANET 2009