VANET 2009
Eun Kyu Lee, Young Min Yoo, Chan Gook Park,
Minsoo Kim, and Mario Gerla

RFID applications
◦ RFID-enabled vehicular applications

RFID system
◦ RFID read performance



2
Installation of RFID system on vehicle
Road test
Conclusion
Supply Chain & Warehouse
ePassport
www.infoworld.com
3
Human implant
www.wikipedia.org
Automatic toll collection
www.ezpass.com
Smart payment
4
www.ti.com


5
RFID system review
RFID communication

What is RFID?
◦ Identify physical objects
Antenna
 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)
02.3DFEX4.78AF51
EasyToll card #816
6
Chip

Tag type
Passive 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

www.hitachi.com &
www.vicariousconversations.com
Radio frequency range
Frequency
HF
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
Contact time
Tag size
Application
- Real-time tracking
- Cheapest
- Multiple-tag contact
Slow ---------------------------------
Robustness
(Sensitivity)
7
Active tag
- Library books
- Access Control
- Sensitive to noise
Fast
Robust
---------------------------------
Sensitive
Big
---------------------------------
Small
- Container
- Real-time location tracking
- Automatic tolling
- Supply chain tracking
- Asset tracking
- Forgery avoidance

Framed slotted Aloha (FSA)
A response from
one RFID tag
Slot
CW
8
Query Cycle
Power
down
CW
Query Cycle
.. .. .
Power
down
.. .. ..


9
RFID-enabled Vehicular Applications
On-board RFID reader system

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
10
Each vehicle is a data producer !!

Tag on vehicle (data producer)
◦
◦
◦
◦
◦
Readers are on the roadside
Automatic toll collection
Intelligent traffic signal system
Electronic license plate
Priority lane management
Enforce
 Lane reservation
and enforcement
www.ti.com
cs.rutgers.edu
Reservation/
Enforcement
System
Enforce
Reserve
Reserve
RFID Reader/
Camera
Lane Entrance
Assistance
System
Low-Priority
Lanes
High-Priority Lane
11

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 reader
RFID tag
12

Tag/reader on vehicle (data prosumer)
◦ Intelligent priority lane management
◦ Peer localization
RFID tag
RFID reader
13

Challenges
◦ High vehicle speed
 Faster than 100Km/h on a freeway
◦ Short communication distance
0.3m
 Much less chance of RFID communication
◦ Random mobility of reader
 Reader position affects performance
significantly than tag placement
 Random fading effects
RFID tag
RFID
reader
14
3m~4m

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
15


Specification of the RFID system
RFID performance
◦ RFID read area
◦ Read latency
◦ RFID read rate
16
Server
RFID reader
Frequency
RF power
Read distance
Modulation
Radio access
910~914MHz
4w EIRP
~5m
ASK
FHSS
RFID reader
antenna
Angle
Gain
Size
60°(3dB)
6 dBi
215x420x55
RFID tag
Data
Data rate
Max pause time
64bit
256kbps
62.5ms
RFID Communication
RFID
Reader
Data
Energy
RFID Reader
Antenna
17
Antenna
EEPROM
RFID Tag
RFID read area

RFID read area
◦ Size and moving speed
RFID Reader
Antenna
h cm
RFID Reader
Antenna
68°
Read area
Front view
X1 cm
Side view
h cm
θ°
68°
Read area
X 2 cm
For instance, if h=37.5cm and θ=45°,
then X1=58.58cm and X2=185.63cm
Measured X2≒100cm (1m)
18
Moving speed of RFID area
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 communication should occur in 1m read area within 36m

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
High possibility of RFID
communication failure

RFID read rate
# of tags successfully read
= ----------------------total # of tags deployed
19
<- 36ms
38.39ms


Experiment setup
RFID reader antenna
◦ Height
◦ Pitch angle
◦ Antenna diversity

RFID tag
◦ Yaw angle
◦ Pitch angle
◦ Tag multiplicity

20
Result

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
18ms of read latency
◦ RFID reader antenna & RFID tag
RFID reader
antenna
RFID tag
21
30°of tag yaw angle and
30°of antenna pitch angle
0.5m

Pitch angle
◦ Varying pitch angle of the antennas
◦ Measure the read area given 18ms of read latency
◦ 30° of pitch angle
Pitch angle of antenna
70°
60
50 °
°
RFID tags are attached
on the floor with 0°
0º
10º
20º
30º
40º
50º
60º
70º
°
40 °
30
20 °
10 °
0°
RFID Reader
Antenna
21cm
21cm
30cm
70° of pitch angle
60°
50°
40°
30°
20°
0°
Floor
50.86
54.62
72.38
73.89
74.40
65.58
66.77
68.95
70cm
10°
22
Length of read area [cm]
Side view

Antenna diversity
◦ Install one and dual antenna(s)
◦ Measure the read area given 18ms of read latency
78 cm
80 cm
RFID Tag
43 cm
RFID Reader
Antenna
RFID Reader
Antenna 1
65 cm
RFID Reader
Antenna 2
1.5m
1 Antenna
3m
0.86m
2 Antennas
23
RFID Tag
1.3m
2m

Yaw angle and pitch angle
◦ Measure the read latency given 0.5m of the read area
30° of reader antenna
◦ Both are set 0°
RFID
Reader
Antenna
Yaw angle
Yaw angle (front view)
er A
d
a
Re
nna
e
t
n
30°
pitch 0 deg
60
pitch 10 deg
50
pitch 20 deg
40
30
20
10
0
-20 -15 -10
0
10
20
30
40
50
60
70
80
30cm
Distance from the center of reader antenna to a
tag [cm]
Pitch
angle
Floor
Pitch angle (side view)
24
Average read latency [ms]
70
RFID Tag
Yaw
angle
0°
30°
60°
90°
120°
150°
180°
Read
latency
44.3
44.2
x
x
x
45.1
46.9

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
Cluster 2
Cluster 3
Cluster 4
40
Average read latency [ms]
Cluster 1
Cluster 1
Cluster 3
35
Cluster 2
Cluster 4
30
25
20
15
10
1
2
3
4
Number of RFID member tags in a cluster
25
5

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
26
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27
Test road configuration
Effect of antenna diversity
Effect of tag multiplicity
Server
RFID
Reader
RFID reader antenna
Number
RFID Reader
Antenna
Height
RFID Tag
Pitch
Test scenarios with variables
1 or 2
Yaw
0°
30cm
Pitch
0°
30°
Member tags
1, 3, or 4
Test1
Test2
Test3
Test4
Test5
Test6
# of antenna
1
2
2
2
2
2
# of member tags
1
1
3
4
3
4
2m
2m
2m
2m
5m
5m
~100
~80
~80
~80
~80
~100
RFID tag interval
28
RFID tag
Maximum speed [km/h]
Deployment
parameters

Effect of antenna diversity
◦ Proof of concept in terms of width
◦ Reduced length does not affect performance much
Average duplication
read [number]
10
1 Antenna
1.5m
Single RFID reader antenna
8
Dual RFID reader antenna
6
4
2
0
10
20
30
3m
50
60
70
80
90
100
Vehicle speed [km/h]
2m
0.86m
40
RFID Tag
1.3m
2 Antennas
Average read rate [%]
Average duplication read
100
Single RFID reader antenna
80
Dual RFID reader antenna
60
40
20
0
10
20
30
40
50
60
Vehicle speed [km/h]
29
Average read rate
70
80
90
100

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
100
1 Tag, 2m Interval (Test 2)
3 Tags, 2m Interval (Test 3)
4 Tags, 2m Interval (Test 4)
3 Tags, 5m Interval (Test 5)
4 Tags, 5m Interval (Test 6)
25
20
90
80
Average Read Rate [%]
Average Duplication Read [number]
30
15
10
60
50
40
1 Tag, 2m Interval (Test 2)
3 Tags, 2m Interval (Test 3)
4 Tags, 2m Interval (Test 4)
3 Tags, 5m Interval (Test 5)
4 Tags, 5m Interval (Test 6)
30
20
5
10
0
0
10
20
30
40
50
60
70
Vehicle Speed [km/h]
Average duplication read
30
70
80
90
100
10
20
30
40
50
60
70
Vehicle Speed [km/h]
Average read rate
80
90
100

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
31
VANET 2009