RFID based design for vehicle location system

RFID BASED DESIGN FOR
VEHICLE LOCATION
SYSTEM
A Thesis
Submitted to the College of Engineering
of Al-Nahrain University in Partial Fulfillment
of the Requirements for the Degree of
Master of Science
in
Computer Engineering

by
HASSAN ABDULSALAM HAMID
(B.Sc., 2006)

Thoul Hijjah 1432
November 2011

Abstracts

Due to the rapid growth in the number of vehicles on the street, traffic
problems are bound to exist. Hence, implementation of Intelligent
Transportation Systems (ITS) to obtain traffic information from roads by
Automatic Vehicle Identification (AVI) is becoming an urgent necessity. The
Radio Frequency Identification (RFID) Technology can be used for AVI to
collect the traffic information in real-time from roads by getting the vehicles
ID from RFID readers.
This thesis tackles the problem of designing Vehicle Location System
(VLS), the proposed system consists of a passive RFID tags on vehicles,
RFID reader, reader's antenna, wireless communication with a Central
Computer System (CCS) and commanding software (RFID middleware and
database structure), also VLS applications, SMS server and website. The
designed system controls, manages and monitors the performance of RFID
readers. It also filters and stores the information in a suitable form to be easily
used in the application system and website. The system implemented by using
Rifidi Platform as simulator for RFID system and VLS is programmed by
Visual Basic 2010. The VLS is composed of installing of two RFID readers in
traffic intersections; each reader has four antennas, for monitoring all entries
and exits of the intersection.
The VLS used the gathered data from traffic intersections RFID readers
in many applications including the following: location of vehicles in
intersections at any time, path and orientation of vehicle in intersections,
numbers and vehicles ID passed in each intersection at any time, estimate the
traffic congestion situation in roads and intersections through SMS server and
websites, drawing path of vehicles within VLS region on map, monitoring
illegal and stolen vehicles real-time and tracking certain vehicle color.

I

List of Contents

Contents Page

Abstract I
List of Contents II
List of Abbreviations IV
List of Tables VI
List of Figures VII

Chapter One: Introduction
1.1 Overview 1
1.2 Literature Survey 2
1.3 Aim of the Work 6
1.4 Thesis Outline 7

Chapter Two: RFID Technology and Applications
2.1 Introduction 8
2.2 RFID System Components 8
2.3 RFID Tags 9
2.3.1 Tag Types 11
2.3.2 Tag operation 12
2.3.3 Electronic Product Code (EPC) Tag 12
2.3.4 Tag Memory 14
2.4 RFID Reader 15
2.4.1 Energize the Tag 17
2.4.2 Frequency ranges 18
2.4.3 Communicate with the Host Computer 19
2.5 RFID Antenna 19
2.6 RFID Middleware 22
2.7 Automatic Vehicles Identification (AVI) based on RFID 25
2.7.1 RFID Hardware’s Properties Requirements 25
2.7.2 Applications of System 26

Chapter Three: The Proposed Vehicle Location System
3.1 Introduction 29
3.2 System Architecture 29
3.3 System Structure 32

II

3.3.1 The VLS Middleware 33
3.3.2 Database 37
3.3.2.1 Traffic Intersections Table 37
3.3.2.2 Vehicles Table 38
3.3.2.3 Data Online Table 38
3.3.2.4 Vehicle Location Table 39
3.3.2.5 Black List Vehicles Table 39
3.3.2.6 Authorized Users Table 39
3.4 Rifidi Platform 39
3.5 Roads and Traffic Intersections Simulation (RTIS) 41
3.5.1. The RTIS Architecture 41
3.5.2. The RTIS Scenario 42
3.6 RFID Readers Connection Protocols 45
3.7 The Methods of VLS Applications 46
3.7.1 Tracking Method for Vehicle Movement 46
3.7.2 Estimation of Traffic Congestion 49
3.8 VLS Client Access 51

Chapter Four: Implementation of Vehicle Location System
4.1 Introduction 54
4.2 Vehicle Location System 54
4.3 The Main Program of VLS 56
4.3.1 The VLS Security 56
4.3.2 The VLS Tables 57
4.3.3 Setting Database and Authorization 63
4.3.4 The Connection with RFID Readers 66
4.3.5 The Traffic Congestion Appraisal 68
4.3.6 The Vehicles Locations Discovery 71
4.3.7 The Vehicle Path Map 71
4.3.8 The Intersection Monitoring and Tracking Vehicle 72
Color
4.4 Traffic Congestion Status Website in VLS 74
4.5 Street Traffic Congestion Appraisal / SMS Server 76
4.6 General Discussion 78

Chapter Five: Conclusions and Suggestions for Future Work
5.1 Conclusions 80
5.2 Suggestions for Future Work 81

References 83

III

List of Abbreviations

AT Attention
AT commands Set of commands used to control the modem
AVI Automatic Vehicles Identification
AIDC Automatic Identification Data Collection
API Application Programming Interface
ASP.Net Active Server Pages.Net
CCS Center Computer System
DHCP Dynamic Host Configuration Protocol
DSRC Dedicated-Short Range Communications
EAS Electronic Article Surveillance
EIRP Effective Isotropic Radiated Power
EPC Electronic Product Code
ETC Electronic Toll Collection
GIS Geographic Information System
GPRS General Packet Radio Service
GPS Global Positioning System
GSM Global System for Mobile Communications
GUI Graphical User Interface
IFF Identity: Friend or Foe
IIS Internet Information Server
IOT Internet of Things
ISO International Standards Organization
ITMS Intelligent Traffic Management System
ITS Intelligent Transport System
PDU Protocol Description Unit
RFID Radio Frequency Identification
RO Read-Only
RTIS Roads and Traffic Intersections Simulation
RW Read-Write
SIM Subscriber Identity Module
SMS Short Message Service

IV

SNMP Simple Network Management Protocol
SQL Structured Query Language
STCA Street Traffic Congestion Appraisal
TCP Transmission Control Protocol
TCP/IP Transmission Control Protocol/Internet Protocol
TICS Traffic Information Collection System
TMS Traffic Management System
UHF Ultra High Frequency
V2I Vehicle-to-Infrastructure
V2V Vehicle-to-Vehicle
VLS Vehicle Location System
VRT Virtual Route Tracking
Wi-Fi Wireless Fidelity
WORM Write Once-Read Many

V

List of Tables

Table Title Page

2-1 EPC RFID classes 13
2-2 EPC RFID chip generations 14
2-3 RFID frequency bands 18

VI

List of Figures

Figure Title Page

(2-1) Components of an RFID system 9
(2-2) Typical design of passive tag 9
(2-3) Passive UHF RFID tag block diagram 10
(2-4) EPC tag content 14
(2-5) Typical electrical connections for RFID reader 16
(2-6) Typical passive RFID tags with different antennas 20
(2-7) Estimation of velocity 28
(3-1) Architecture of traffic intersection in VLS 30
(3-2) Simulation of traffic intersection 31
(3-3) The communication method for VLS system 32
(3-4) The flowchart of the middleware performance 36
(3-5) The vehicles and roads network in RTIS 43
(3-6) The gathered data 44
(3-7) The significance of the gathered data 44
(3-8) The connection between client and server on 45
specific port
(3-9) Principle of VRT algorithms 46
(3-10) The flowchart for drawing the VRT on the map 48
(3-11) The flowchart for traffic congestion estimation 51
(3-12) GSM modem communications 52
(4-1) The layout of the VLS environment 55
(4-2) The implemented VLS 55
(4-3) Main form of VLS 56
(4-4) The security form 56
(4-5) Traffic intersection table 57
(4-6) Vehicles table 58
(4-7) Data online table 59
(4-8) Vehicle location table 59
(4-9) Black list vehicles table 60
(4-10) The vehicle which in black list is detected 60
(4-11) Deleting vehicle ID from black list table 61
(4-12) Tables update form 61
(4-13) Update of traffic intersections table 62
(4-14) Update of vehicles table 63

VII

(4-15) Setting database and authorization 63
(4-16) A message of cleaning tables successfully 64
(4-17) Restore database 65
(4-18) Password change form 65
(4-19) The connection form with RFID readers 66
(4-20) The connection shutdown irregularly 67
(4-21) RFID readers table 67
(4-22) The connection stream 68
(4-23) The traffic intersections congestion appraisal 69
(4-24) The street traffic congestion appraisal 70
(4-25) The vehicles locations discovery 71
(4-26) The vehicle path map 72
(4-27) The Intersection Monitoring 73
(4-28) Tracking vehicle color 73
(4-29) The website of intersection congestion estimation 75
(4-30) The website of street congestion estimation 75
(4-31) Street Traffic Congestion Appraisal / SMS Server 76
(4-32) Sony Ericsson GSM Modem Configurations 77

VIII

Chapter One
Introduction

1.1 Overview

The modernization of transport has become one of the essential signs
for the urban modernization level, the increase in the number of cars leads to
serious problems concerning transport system. With the development of the
technology of computer, communication, electron, information and
intelligence has become important factors in achieving convenient and
efficient transport system. According to these circumstances, the Intelligent
Transport System (ITS) came into existence [1]. Collection of transportation
information systems based on conventional detection techniques such as loop
detectors, video image processing, and Dedicated Short Range
Communication (DSRC) leads to high installation and maintenance costs, the
high costs prevented the proliferation of these detection techniques [2].
Radio Frequency Identification (RFID) technology is one of the most
rapidly growing segments of today's Automatic Identification Data Collection
(AIDC) industry [3]. Using "RFID tags" on objects or assets, and "RFID
readers" to gather the tag information, RFID represents an improvement over
bar codes in terms of non-optical proximity communication, information
density, and two-way communication ability. It can automatically identify
target and obtain relevant data without contacting with the target. It has many
advantages such as high precision, easy adapting ability and quickly operation
and so on. Moreover, it is able to work under harsh environment and reads
from long distance [4].

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Automatic Vehicles Identification (AVI) system based on RFID is
design for all legally registered vehicles; these vehicles must hold RFID tags.
When these vehicles travel along a road or intersection which is installed AVI
system (RFID reader), the information of vehicle tag is read and sent
immediately to Center Computer System (CCS) for achieving the purpose of
real-time monitoring and management for vehicle movement conditions. The
CCS receives the information and position of the vehicle from traffic
intersection and then analyzes and filters to store it in database [5].

1.2 Literature Survey

In an endeavor to enhance efficiency and safety in transport systems,
research is being done in RFID applications in smart E-parking, toll
collection, virtual route tracking, digital traffic light control and with some
other RFID applications. Several designs of such systems are given in the
following literature:
 S. Tenqchen et al. in 2006 [6] proposed a website to exhibit the traffic
information for every 5 minutes at certain places of street measured by
three RFID readers for 125 tags installed on two different urban-bus
companies and transmit that information via GPRS modem from testing
point to control center. Each data can be used to indicate the exact point
of traffic condition in a big city. Three different readers installed in
certain places; those readers are used to collect traffic information by
recording the tag’s information of incoming urban-buses. The result
shows that the application of RFID tag and reader is an alternative way
to extract the traffic information instead of traditional loop detector.
 J. D. Tseng et al. in 2007 [7] proposed a vehicle management system
based on UHF band RFID technology. The system is applied for

2

vehicle entering/leaving at road gates. The system consists of tag-on-
car, reader antenna, reader controller, and the monitoring and
commanding software. The entering time, leaving time, and tag number
of each vehicle are all recorded and saved for further processing. The
experimental results demonstrated the proposed system is reliable on
this application. The system could not only reduce the cost of guard and
payload in the maximum by the decrement of manpower, but also
promote the security and efficiency of the parking lot.
 M. Kim et al. in 2008 [8] developed an active RFID - based national
Traffic Information Collection System (TICS) in ubiquitous
environments. RFID readers have been installed at 130 spots and
operate as 65 pairs at road side to obtain speed and location of vehicles.
Active RFID tags are attached to 2,000 vehicles including normal cars,
taxies and buses. The tag information is sent to middleware in the
central center through the communication network, processed and
saved in database, and utilized by various traffic related applications.
Experiments were performed for four months. As time goes, the
number of recognized tag identifiers decreases quite fast due to battery
failures, detached tags, and other reasons.
 K. A. S. Al-Khateeb et al. in 2008 [9] developed an intelligent RFID traffic
control, to solve the traffic congestion problem. RFID technology with
appropriate algorithm and data base were applied to provide an
efficient time management scheme. The simulation result has shown
that, the dynamic sequence algorithm has the ability to intelligently
adjust itself even with the presence of some extreme cases. The real
time operation of the system emulated the judgment of a traffic
policeman on duty, by considering the number of vehicles in each
column and the routing proprieties. The great challenge would be to

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design a system that is capable of understanding and identifying traffic
movement for a whole city. Understanding the routine traffic pattern
can provide accurate information to the traffic planner or urban
designer to develop a traffic jam free city.
 Y. Zhang in 2009 [10] proposed a framework in which moving vehicles
with attached passive RFID tags can be located with RFID readers
installed at the roadside near the road intersections thus to improve the
ITS traffic real-time road status. A challenging issue in his approach is
to avoid multiple RFID reader collision problems to ensure the integrity
of traffic sampling data. The location information of road intersection is
preloaded in RFID reader. By tracing individual vehicles’ information
the system can evaluate the road status throughout the city.
Implementations have been conducted to evaluate the feasibility of the
proposed framework.
 H. He and Y. Zhang in 2009 [11] introduced a new method based on RFID
technology to get the vehicle running state parameters. Vehicle
traveling data recorder (which is also called automobile block box) can
accurately record the state parameters of the automotive traveling
process, which can offer a real, effective and scientific legal basis for
the analysis of traffic accidents. The system adds RFID module on the
base of the traditional vehicle traveling data recorder, which achieves
non-stopping to get the vehicle’s running parameters on some section
of highway. The tag module of this system adopts Mifare1 S50 card,
the reader module uses MCM200 produced by PHILIPS Company; and
the system takes Linux as the operating system. The results show that
the system has a small volume, complete function, high reliability and
high performance ratio.

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 H. Tao et al. in 2010 [12] proposed management system optimized design
to solve traffic intersection problems in the management of traditional
vehicles. The system includes the hardware architecture and system
software. At the four directions of the intersection (e.g. east, south,
west, north), in each direction to set two RFID readers, they can
simultaneously scan in the reverse direction from the two vehicles, and
can record relevant information for each vehicle, including the vehicle
electronic tag encoding and the driver electronic label encoding.
 Z. Feng et al. in 2010 [13] designed the vehicle path recognition based on
RFID and an Electronic Toll Collection (ETC) system of expressway.
The ETC system will toll collection without parking, also census traffic
flow and audit road maintenance fees. It uses 920MHz passive RFID
tag as carrier to identify actual vehicle path. High-speed long-distance
UHF reader is installed in all sections of the monitoring points and
highway entrances and exits, so as to automatically read the electronic
tag information carried by the vehicles pass through the marking
station, so that the system can record the driving path.
 Iswanjono et al. in 2011 [14] proposed an algorithm for predicting the
speed of traffic light violators. The traffic light system is equipped
RFID reader as the main tool for identifying the vehicle's RFID tags.
The simulation by Scilab simulator gives evidence of violation and
prediction of vehicle flow. The violation can detect if the vehicle's IDs
have moved from one RFID reader to the others. A randomization
generates vehicle IDs, vehicle numbers and vehicle branch destination
that can show the function of RFID reader to detect tags. From the
simulation conducted, the algorithm is able to predict the speed of
traffic light violators ranging from 5 km/h up to 80 km/h in real-time.

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 M. Yu et al. in 2011 [15] implemented active RFID tag based system for
automatically identifying running vehicles on roads and collecting their
data. The design principles and the architecture of the system includes
active electronic tags and reading equipment (readers and antennas),
the monitoring base station deployment, the two-layered network
construction, and the monitoring software. The system used electronic
tag and reading base station is based on SCM C8051F920; it is a low-
power high-speed general with a 24.5MHz oscillator, and a
programmable flash memory. The effectiveness and efficiency of the
system is analyzed. The system will have wide applications in traffic
IOT (Internet of Things) to support traffic monitoring, traffic flow
statistics, traffic scheduling, and special vehicle tracking.

1.3 Aim of the Work

The aim of this work is to show how technologies of identification by
RFID can be used to build VLS by collecting the traffic information in urban
cities. This work is designed to monitor the traffic intersections in real-time
via RFID system. This will be applied in all intersections for each vehicle.
This is achieved by installing RFID readers in the traffic intersections and
attaching RFID tags in vehicles. Then, the VLS will use the acquired
information in several applications of ITS as the following:
 Discovery the vehicles locations.
 Displaying the route of the vehicle on the city map.
 Monitoring the intersections.
 Tracking vehicles color.
 Tracking the illegal and robbed vehicles in real-time.
 Estimating the status of congestion in roads and traffic intersections.

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1.4 Thesis Outline

This thesis is organized in five chapters. The contents of the following
chapters are briefly reviewed as follows:
 Chapter Two: This chapter explains RIFD technology and RFID
system components like readers, tags and host system. Then specify the
discussion on using RFID technology in transport systems.
 Chapter Three: This chapter discusses the proposed VLS, VLS
structure, the database of VLS, RFID simulation and the methods of
VLS applications.
 Chapter Four: This chapter discusses the implementation of VLS,
SMS server and websites.
 Chapter Five: This chapter includes conclusions and suggestions for
possible future work.

7

Chapter Two
RFID Technology and Applications

2.1 Introduction

RFID technology is currently being used in numerous applications
throughout the world [3]. RFID is not a new technology, for example, the
principles of RFID has been employed by the British in World War II to
identify their aircraft using the IFF system (Identity: Friend or Foe) [16], and
it is still being used today for the same purposes.
RFID uses tags to transmit data upon RFID reader queries. RFID tag
responds to a reader query with its fixed unique serial number (tag ID). This
fixed tag ID enables tracking of tags and the bearers. In addition to the unique
serial number, some tags carry information about the objects they are attached
to [17]. RFID is used for a wide variety of applications ranging from the
familiar building access control proximity cards to supply chain tracking, toll
collection, vehicle parking access control, retail stock management, tracking
library books, theft prevention, etc.

2.2 RFID System Components

RFID is a generic term for technologies that use radio waves to
automatically identify people or objects. There are several methods of
identification, the most common of which is to associate the RFID tag unique
identifier with an object or person. RFID system (as shown in Fig. 2-1) will
typically comprise the following [4]:
 RFID tag.

8

 RFID reader with an antenna and transceiver.
 A host system or connection to an enterprise system.

Figure 2-1 Components of RFID system [18]

2.3 RFID Tags

The tag, also known as the transponder (derived from the terms
transmitter and responder), holds the data that is transmitted to the reader
when the tag is interrogated by the reader. The most common tags today
consist of an Integrated Circuit (IC) with memory, essentially a
microprocessor chip [19], see Fig. 2-2.

Figure 2-2 Typical design of passive tag [3]

9

The implementation of a passive UHF RFID tag is shown in Fig. 2-3, a
block diagram of RFID tag using backscatter modulation. The tag consists of
tag antenna and tag chip. The tag chip contains a RF-analog front end (voltage
rectifier, clock generator, modulator and demodulator), a digital control block,
and a non-volatile memory [17].

Figure 2-3 Passive UHF RFID tag block diagram [17]

Other tags are chipless and have no onboard IC. Chipless tags are most
effective in applications where simpler range of functions is required;
although they can help achieve more accuracy and better detection range, at
potentially lower cost than their IC-based counterparts [19].
When a tag is interrogated, the data from its memory is retrieved and
transmitted. A tag can perform basic tasks (read/write from/to memory) or
manipulate the data in its memory in other ways [19].
RFID tags can interfere with each other. When multiple tags are present
in a reader‟s field, the reader may be unable to decipher the signals from the
tags. For many applications, such as raising the gate in a parking lot, this is
not a problem. The systems are optimized so that only one tag is within range
at a time. However, for other applications, reading multiple tags at once is
essential, for these applications, the tags need to support an anti-collision
protocol to allow each tag reads without interference from the others [20]. An
effective anti-collision algorithm can reduce the operating time and increase

10

the read rate. Two algorithms, slotted ALOHA and binary search, are always
used in the RFID protocol. The slotted ALOHA algorithm needs a
synchronous signal and a longer time to process when more tags are in
collision. Also the discrimination ratio is not as high as that with the binary
search algorithm. However, the binary search algorithm has strict
requirements for its computing slot and bad security [21].

2.3.1 Tag Types
RFID tags fall into two broad categories: those with a power supply (a
battery) and those without. RFID tag that actively transmitted to a reader is
known as „„active tags‟‟. Unpowered passive tags are known as „„passive
tags‟‟. Active tags are typically also read/write tags while passive tags are
generally read only.
Active tags are larger and more expensive than passive tags. The use of
a battery places a limit on the life of the tag, although with current battery
technology this may be as much as 10 years [4].
Passive tags have an unlimited life, are lighter, smaller and cheaper.
The trade-off is limited data storage capability, a shorter read range and they
require a higher-power reader. Performance is reduced in electromagnetically
„„noisy‟‟ environments.
There are also semi-passive tags where the battery runs the chip‟s
circuitry but the tag communicates by drawing power from the reader.
Tags are available in a wide variety of shapes, sizes and protective
housings. The smallest tags commercially available measure 0.4 x 0.4 mm
and are thinner than a sheet of paper [4].

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2.3.2 Tag operation
In LF or HF systems, tag-to-reader communication is achieved via inductive
coupling (load modulation). Load modulation is achieved by modulating the
impedance of the tag as seen by the reader. In UHF or above systems, tag-to-
reader communication is achieved via propagation coupling (backscatter).
Backscatter is achieved by modulating the radar cross section of the tag
antenna [3].
In load modulation process, when a tag is placed within the alternating
magnetic field created by the reader, it draws energy from the magnetic field.
This additional power consumption can be measured remotely as a voltage
perturbation at the internal impedance of the reader antenna. The periodic
switching on/off of a load resistance at the tag therefore affects voltage
changes at the reader‟s antenna and thus has the effect of an amplitude
modulation of the antenna voltage by the remote tag. If the switching on and
off of the load resistance is controlled by the tag‟s stored data stream, then
this data is transferred from the tag to the reader. In load modulation the
carrier signal is modulated by switching impedance from a matched condition
to an unmatched condition to alter the reflection coefficient [3].
In backscatter modulation process, a reader sends a signal (energy) to a
tag, and the tag responds by reflecting a part of this energy back to the reader.
A charge device such as a capacitor contained in the tag makes this reflection
possible. The capacitor gets charged as it stores the energy received from the
reader. As the tag responds back, it uses this energy to send the signal back to
the reader. The capacitor discharges in the process [19].

2.3.3 Electronic Product Code (EPC) Tag
The specifications for UHF passive tags and RFID readers developed first by
the Auto-ID Center and then by EPCglobal, a standards body that was formed

12

from the article-numbering barcode associations around the world, to promote
the use of RFID in commerce [21]. At the heart of the EPC suite of standards
is the EPCglobal EPC Gen2 protocol (as well as its counterpart ISO 18000-
6c) that specifies the air interface protocol for communication between
readers and tags [3]. The EPC Gen2 protocol is a very powerful one with a
number of features almost unimaginable in a lower-cost tag even a few years
ago [21]. EPCglobal has defined a series of RFID tag “classes” and
“generations” of RFID tags, see Tables 2-1 and 2-2.

Table 2-1 EPC RFID classes [20]

13

Table 2-2 EPC RFID chip generations [20]

The EPC tag data standard specifies the format for encoding and
reading data from 96-bit RFID tags, as shown in Fig. 2-4.

Figure 2-4 EPC tag content [4]

2.3.4 Tag Memory
A tag's memory attribute can be read-only (RO), write once-read many
(WORM), or read-write (RW), see Table 2-1. Memory write capability

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generally increases the cost of a tag, along with its capability to perform
higher-level functions. At the same time, read-only tags eliminate the risk of
accidental or malicious over-writing of tag data [19].
Tag memory configurations can vary greatly based on cost and physical
requirements. In case of Electronic Article Surveillance (EAS), tags have
essentially 1 bit of memory and are relatively inexpensive when compared to
tags with more memory. These tags have no unique identifiers and are used
only to signal their presence when they are in the field of a reader. Beyond the
1-bit tags, typical memory footprints can range from 16 bits to several
hundred Kbits for certain active tags. The amount of memory present on a tag
is then defined by application requirements and/or any relevant standards or
regulations. For example, due to the expected global acceptance of the
EPCglobal standards, the memory size for the newer generation of passive
tags will be 2 Kbits or more [19].

2.4 RFID Reader

Reader, as a scanning device, detects the tags that attached to or
embedded in the selected items. It varies in size, weight and may be stationary
or mobile. Reader communicates with the tag through the reader antenna, as
shown in Fig. 2-5, which broadcasting radio waves and receiving the tags
response signals within its reading area. After the signals from tags are
detected, reader decodes them and passes the information to middleware [18].
The reader for a read/write tag is often called an interrogator. Unlike
the reader for a read-only tag, the interrogator uses command pulses to
communicate with a tag for reading and writing data [3].

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Figure 2-5 Typical electrical connections for RFID reader

RFID reader sends a pulse of radio energy to the tag and listens for the
tag‟s response. The tag detects this energy and sends back a response that
contains the tag‟s serial number and possibly other information as well.
Historically, RFID readers were designed to read only a particular kind
of tag, but so-called multimode readers that can read many different kinds of
tags are becoming increasingly popular.
Like the tags themselves, RFID readers come in many sizes. The
largest readers might consist of a desktop personal computer with a special
card and multiple antennas connected to the card through shielded cable. Such
a reader would typically have a network connection as well so that it could

16

report tags that it reads to other computers. The smallest readers are the size
of a postage stamp and are designed to be embedded in mobile telephones
[20].

2.4.1 Energize the Tag
In the case of passive and semi-active tags, the reader provides the energy
required to activate or energize the tag in the reader's electromagnetic field.
The reach of this field is generally determined by the size of the antenna and
the power of the reader. The size of the antenna is generally defined by
application requirements. However, the power of the reader (through the
antenna), which defines the intensity and reach the electromagnetic field
produced, is generally limited by regulations. Each country has its own set of
standards and regulations relating to the amount of power generated at various
frequencies. For this reason, incompatibilities do exist between RFID systems
in various countries [19].
EPCglobal and ISO created standards to solve this problem. EPCglobal
initiated the creation of a standard to facilitate full-scale interoperability
between multivendor RFID systems and to propel RFID technology into a
broad array of markets. EPCglobal established and supports the EPC as the
worldwide standard for immediate, automatic, and accurate identification of
any item in the supply chain. EPCglobal is sponsored by many of the world's
leading corporations and it has published a set of RFID protocol standards
(see sec. 2.3.3).
Also, ISO is a network of the national standards institutes of 148 countries,
making it more global and governmental than EPCglobal. ISO bridges the
needs of the public and private sectors, focusing on creating standards and
building universal consensus for the acceptance of those standards [19].

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2.4.2 Frequency Ranges
One of the more important aspects of a tag and reader connection (coupling)
is the frequency at which it operates. Frequency allocations are generally
managed through legislation and regulation by individual governments.
Internationally, there are differences in frequencies allocated for RFID
applications although standardization through ISO and similar organizations
is assisting in compatibility [4].
In general, the frequency defines the data transfer rate (speed) between
the tag and the reader. Lower frequency performs slower transfer rate.
However, speed is not the only consideration in designing RFID solution.
Environmental conditions can play a significant role in determining the
optimal operating frequency for a particular application.
Higher frequency usually means smaller antenna, smaller tag size, and
greater range and typically, more regulatory of use restrictions and often,
higher cost [19]. Table 2-3 summarizes the most popular frequency bands,
and characteristics.

Table 2-3 RFID frequency bands [16]

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2.4.3 Communication with the Host Computer
The reader is also responsible for the flow of data between the tags and the
host computer. Typically the reader communicates with a host computer
through a Serial or Ethernet connection. A reader may also be equipped to
communicate with the host computer through a wireless connection,
particularly if the reader is a portable or handheld device [19].

2.5 RFID Antenna

The reader antenna establishes a connection between the reader
electronics and the electromagnetic wave in the space. In the HF range, the
reader antenna is a coil (like the tag antenna), designed to produce as strong a
coupling as possible with the tag antenna. In the UHF range, reader antennas
(like tag antennas) come in a variety of designs. Highly directional, high-gain
antennas are used for large read distances [3].
Antenna design and placement plays a significant factor in determining
the coverage zone, range and accuracy of communication [19]. Physical
interdependencies mean that the antenna gain is linked to the antenna size.
The higher the gain (or the smaller the solid angle into which the antenna
emits), the larger the mechanical design of the antenna will be. All other
things being equal, a high-gain antenna will transmit and receive weaker
signals farther than a low-gain antenna. Omnidirectional antennas, such as
dipole antennas, will have lower gain than directional antennas because they
distribute their power over a wider area. Parabolic antennas usually have the
highest gain of any type of antenna [3].
The tag antenna is usually mounted on the same surface as the IC and
packaged as a single unit. Fig. 2-6 shows several common passive tag and
antenna configurations. Although the tag IC can be tiny (the size of a grain of

19

rice or smaller), the size and shape of the antenna typically determines the
limits of the dimensions of the entire tag packaging [19].

Figure 2-6 Typical passive RFID tags with different antennas [19]

Let the power transmitted by the reader be and the gain of the
reader antenna be Greader. The power density at distance R where the tag is
placed can be expressed as

The power received by the tag is calculated by

Where

Then

20

The power density of the return wave from the tag at the position of the reader
is

Thus the power received by the reader is

That is

Where Greader stands for the gain of the reader antenna, Areader the equivalent
aperture of the reader antenna, Gtag the gain of the tag antenna, and Atag the
equivalent aperture of the tag antenna.
Where Effective Isotropic Radiated Power (EIRP) is the power transmitted by
the reader, the equivalent transmitted power as

Then

Denote by the threshold power of the sensitivity. Then the maximum
reading range is expressed as

21

Now we analyze the RFID system by using the radar principle. Suppose that
the backscattering section of the tag, including the antenna and the chip, is
σtag, then the backscattering power of the tag is

The power density of the backscattering wave at the position of the reader is

So we have

By adjusting the tag chip impedance according to the stored data in tag, σtag
will be changed, and then the return wave coming from the tag and received
by the reader will be changed such that the amplitude modulation and
demodulation can be realized. In this manner, the tag information can be read,
and the object detected by the tag can be identified [22].

2.6 RFID Middleware

A middleware, as the name suggests, is a piece of software that lies
between a lower layer processing device or software and an upper layer server
or software, usually at the application level. Therefore, data from RFID
readers are sent to a middleware platform that acts as a bridge between RFID
readers and host application software [23] [24].
Typically, RFID middleware platform performs aggregation of data
across different readers, filtering of unwanted or noisy RFID data, forwarding
of relevant data to subscriber servers or application-level systems, and
persistent storage for context aware and other added value services. However,

22

RFID middleware is often given the task of managing, monitoring and
configuring the different readers and interrogators. The middleware performs
monitoring task on RFID readers to check operational status of the readers.
This is a very important function, especially when readers are located in
distributed manner, and manual monitoring is impractical [23] [24].
According to the main functionalities hosted by RFID middleware platform
can be classified as follows [23]:
1- Configuration Service Set
 Network interface configuration. Discovers and sets reader
networking parameters and identity, e.g. the IP address.
 Firmware management. Distribute and manage firmware version on
readers
 Antenna, tag population and memory selection. Specify reader
antennas and tag population to be inventoried. In case of tag memory
access, specifies memory fields to be accessed.
 Base service set scheduling. Sets how different services, such as tag
inventory, access, and deactivation, are triggered and stopped.
 RF transmitter configuration. Sets transmit channel, hop sequence,
and transmit power for readers.
 Air interface protocol configuration. Configures timing, coding and
modulation parameter of a specific air interface protocol on the readers.
2- Data Processing Service Set
 Filtering. Removes unwanted tag identifiers from the set of tag
identifiers captured, e.g. based on the product type or manufacturer
encoded in the identifier.

23

 Aggregation. Computes aggregates in the time domain (entry/exit
events) and the space domain (across reader antennas and readers) and
generates the corresponding “super” events.
 Identifier translation. Translates between different representation of
the identifier, e.g. from raw tag object identifier in hexadecimal format
to EPC.
 Persistent storage. Stores RFID data captured for future application
requests.
 Reliable messaging. Allow RFID data to be delivered reliably in the
presence of software component, system and network failures.
 Location/Movement estimation. Detects false positive reads of far-
away tags that are outside the “typical” read range and estimate the
direction of movement.
 Application Logic execution. Interprets the RFID data captured in an
application context and generate the corresponding application events,
e.g. detect whether a shipment is complete.
3- Monitoring Service Set
 Network connection monitoring. Check that the reader can
communicate captured RFID data over the network
 RF environment monitoring. Check RF noise and interference levels
to safeguard reliable identification operation
 Reader Monitoring. Check that the reader is up, running and
executing as configured for example via monitoring the number of
successful/failed read and write operations.
Now, not all these functionalities are mandatory to be hosted by the
middleware. This depends on the reader architecture employed. Two types of
architectures can be followed: one in which many of the above functionalities

24

are hosted by the reader itself, which will be called decentralized reader
architecture, and the one in which all the functionalities, except the basic ones
used in the reader, will be hosted by the middleware platform or a controller
appliance [23].

2.7 Automatic Vehicles Identification (AVI) based on RFID

AVI system based on RFID is a design that covers every vehicle legally
registered which carries RFID tag. When these vehicles travel along a road in
which AVI system is installed, all kinds of vehicles information of car tag is
read and transmitted in real-time to data processing controlling unit realizing
the purpose of real-time monitor and management for vehicle operating
conditions [5].
The main components of the AVI system based on RFID include: (i)
hardware, i.e. passive RFID tags and readers for generation of traffic
information; (ii) RFID middleware and database structure, and application
software consisting of real-time process; and (iii) network architecture to
deploy AVI system nationwide [8].

2.7.1 RFID Hardware’s Properties Requirements
Using RFID in AVI systems that requires specific properties for RFID
reader‟s devices to realizes the system requirements. The following
characteristics should be available in RFID reader for using it in AVI system:

1. Multi-tags recognition rate
2. High tag recognition speeds
3. Operating in UHF or higher frequency
4. Read only (not need writing in tags)
5. Large coverage distance, for 9 meters or higher

25

6. The antenna is separated from reader‟s device (not incorporated
with reader)
7. Support multi-static antenna system (transmit and receive)
8. Support for multiple antenna‟s ports, four or more
9. Support for Ethernet connection, TCP/IP

2.7.2 Applications of System
The ITS based on RFID technology is a comprehensive managing system,
which integrates information technology, communication technology,
automatic control technology and information processing technology,
combines traffic planning, traffic engineering and traffic management as a
whole to enhance traffic capability. The communication between road and
vehicles is one of the key technologies [1].
The application of RFID technology in ITS is widely utilized at the present
time and in the future. The following list of applications of AVI system based
on RFID:
1. Electronic Toll Collection (ETC) System
ETC system adopted in highways can solve many problems brought by
traditional way of charging, such as time-consuming and inconvenience
of supervision. The system can read the ID number from the vehicles
affixed with RFID tags, and transmits the information to the manage
center through network under the control of the RF controller, with the
exact passing time and the driveway number. The ETC system will
charge automatically according to the passing time and give green light
to the cars with the effective tags, and hold up the cars without card or
the null card [1] [25] [26].

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2. Gate Automatic Identification System
RFID technology could also be utilized in some military places,
parking places, communities and confidential departments by adopting
GAI system. When the vehicles affixed with RFID tags approach the
driveway, the system can get the ID of RFID tags, and transmits the
vehicles‟ information to the manage center. Then, the manage center
decides whether or not give green light the vehicles, by means of
sending control order to the executive machine. Under the surveillance
of GAI system, it can identify all the passing cars and give green lights
to the cars which have been registered (affixed with effective RFID
tags), solving the problems often existed in the traditional way of
household guards, which often causes big loss, inconvenience, and
feelings of insecurity, etc. [1].
3. Automatic Equipment Identification System
AEI systems are mainly used in the identification of the containers,
such as application to the sea, road and rail containers transport or
logistics management with the advantages of both safety and
convenience. RFID tags would be affixed to these containers, with the
information of containers‟ number, quantity, and the shipping sites and
its destination. Once the containers are shipped to the port of
destination, AEI system would read the information via the automatic
identification, and then exchange information with these tags [1].
4. Vehicles Speed Estimation
The speed of vehicle is estimated to check if vehicle exceeded the
limited speed of street or not. The speed of vehicle is estimated based
on measured detection time difference and distance between two
readers. To estimate the velocity of the vehicle, two RFID readers must
be installed [24].

27

Figure 2-7 Estimation of velocity [24]

As shown in Fig. 2-7, (d1) is the distance between reader A and the
vehicle, (d2) is the distance between the readers and (d3) is the distance
between reader B and the vehicle. Then, the velocity of the vehicle
calculates as

Where t1 and t2 denote the communication moment between readers
and tags.
Other applications of AVI system fall in many fields [5,27-30] such as smart
E-parking, intelligent security management system, customs electronic license
plate AVI system, public transport e-ticketing, missing and stolen vehicle
tracking system, virtual route tracking, TICS, traffic violation monitoring,
variable speed limits, enhancement of driver‟s situation awareness, collision
avoidance systems, Intelligent Traffic Management System (ITMS), digital
traffic light control, the data dissemination between vehicle-to-infrastructure
(V2I) or vehicle-to-vehicle (V2V), etc.

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Chapter Three
The Proposed Vehicle Location System

3.1 Introduction

This chapter discusses the design of VLS which consists of CCS, SMS
server and websites. The CCS contains the middleware, database management
and the system applications. The RFID readers of VLS are simulated to
evaluate the system works and test its ability to collect and manage the traffic
information from several RFID readers in real-time.
The middleware is programmed to connect the VLS with readers from
one side and with database on the other, and to arrange the information that is
received from readers in appropriate format to be used in the application
system and website. Wireless communication system is used to communicate
the CCS with readers.

3.2 System Architecture

The first step in the VLS is to attach RFID tag to all vehicles that can
be identified by RFID readers. It is suggested that the data is stored in tag
only be tag ID and without any other details of vehicle, so to keep the persons'
privacy of the vehicles’ owners. In this form no privacy’s information is
available, and if any snooper tries to install illegal reader to snoop, he cannot
enter to the private information of vehicle owner, he will save the normal
information like he records the information by sight to vehicle license plate.
The VLS is composed of installing of two RFID readers in each traffic
intersections, as shown in Fig. 3-1. The four branches of the traffic

29

intersection are North, East, South and West were represented as Road 1,
Road 2, Road 3 and Road 4 respectively. In each branch set two RFID
antennas, they can simultaneously scan in the opposite directions from the
two vehicles, and these antennas can record relevant information for each
vehicle.

Figure 3-1 Architecture of traffic intersection in VLS

In each branch, two antennas are installed in the mid island of the road
near the traffic intersection, and separated by a convenient distance. In this
architecture of arranging the direction of antennas, each antenna's RF
radiation areas do not overlap each other.
The RFID antennas are numbered as 0, 1, 2 and 3. The even antennas
are installed on the ways-in of intersections while the odd antennas are
installed on the ways-out of intersections. Hence, for reader 1 install antenna
(0) is on way-in of road 1, antenna (2) is on way-in of road 2, antenna (1) is

30

on way-out of road 1 and antenna (3) is on way-out of road 2, so for reader 2
in roads 3 and 4, see the simulation of traffic intersection in VLS in Fig. 3-2.

Figure 3-2 Simulation of traffic intersection

In CCS, according to the order of receiving the same tag ID from two
different antennas, the direction of vehicle movement will be known from its
entry and to its exit. In this architecture of the system, the VLS will monitor
the path direction for all vehicles in the traffic intersections in real-time.
In the proposed VLS, RFID readers communicate with CCS via
wireless network, RFID reader is connected with wireless station by STP
cable, while the wireless access point is connected with CCS directly by UTP
cable. The stations communicate with access point as shown in Fig. 3-3.

31

Figure 3-3 The communication method for VLS system

3.3 System Structure

The VLS components are divided into two parts: software and
hardware. The software part is implemented while the hardware part is
simulated. The software part is programmed by using (Microsoft Visual Basic
2010 program) that works in (Microsoft .NET Framework 4.0) environment
and the large database system is designed by (Microsoft SQL Server 2008 R2
Management Studio).
The hardware part of VLS consists of RFID readers and tags, wireless
network, CCS, GSM modem, database's storage memory and cables.
In VLS, the RFID readers are simulated by the use of Rifidi Platform
(see sec. 3.4) and Roads and Traffic Intersections Simulation (RTIS) (see sec.
3.5).
In brief, the following components are used for building VLS system:

32

 Two computer devices (one as RFID reader(s) via Rifidi and/or
RTIS simulators and another for CCS)
 Wi-Fi system
 Microsoft Visual Basic 2010 with .NET Framework 4.0 and
Microsoft ASP .NET Web Site Designer.
 Microsoft SQL Server 2008 R2 Management Studio
 Sony Ericsson GSM Modem

3.3.1 The VLS Middleware
The middleware is the software program (see sec. 2.6) used to establish the
connections with several RFID readers synchronous and communicate with
them. On the other side, it connects with SQL Server Management Studio to
communicates with database.
To connect VLS to RFID reader the middleware must have the following:
1- Traffic Intersection ID
2- RFID reader IP and Port
3- RFID reader Username and Password
To get this information, the system should communicate with the database
and request this information from Traffic Intersections Table (see sec. 3.3.2).
After getting the traffic intersection ID, IP, Port, Username and Password, the
system will achieve connection with that reader. After the connection is
accomplished, the system sends (Get TagList) request. The reader will reply
by the list of tags that is gathered from antennas. Each tag's information is
sent as a form of one packet, see a flowchart in Fig. 3-4.
The packet information is filtered as tag ID, antenna number, date and
time. This information will be stored in Data Online Table.
Then check antenna number whether even or odd (see sec. 3.2). If the
antenna number is even, the packet data are stored in temporary table, and if

33

the antenna number is odd, the system requests to search in temporary table
on that tag ID. When fetch the even packet with odd packet, the system infer
the vehicle ID from tag ID that is passed through, traffic intersection ID,
from-road, to-road, date, in-time and out-time. The inferred information will
be stored in the Vehicle Location Table.
The next step is to check whether this vehicle ID is in Black List Table
or not. If this is detected, the system displays warning message that the
vehicle passed through the traffic intersection ID, from-road, to-road, date,
and time.
Then, the following step checks the connection with that reader if still
connected or not. If not, the system will display (The reader -ID- is
disconnected or turn off) message.

34

Start

Load from database: Reader’s IP,
Port, Username and Password

Connecting with
reader via socket

Connection No Display: Can’t
established? connect to reader
Yes

Display:
Login Successfully
1

Send: Get TagList

Receive: Tag List

Yes
No tags?

No

Analyzing data into:Vehicle IDs,
Date, Time and Antenna No.

Storing data in
data online table

2 3

35

2

Yes
Is antenna Storing in
no. even? temporary table

No
Looking for vehicle ID in
temporary table

No
Display:
ID found?
Miss Data
Yes
Store in vehicle location table: Vehicle
ID, Intersection ID, from-road, to-road,
date and time (in-out)

Looking for vehicle ID in
black list table

Yes Display:
ID found?
Warning
No

Connection Yes
1
Status: OK?
No
Display: Reader is
disconnected or turned off

3

End

Figure 3-4 The flowchart of the middleware performance

36

3.3.2 Database
All RFID systems require smart database for storing all data received from
readers in real-time. Microsoft SQL Server 2008 R2 Management Studio was
selected to build the VLS's database, as it is robust compatible with Microsoft
Visual Basic 2010 and Visual Basic support special Application Programming
Interface (API) command to communicate with it. Also SQL has fast response
and effective with robust request such as in one instruction that can query
many tables. Besides, SQL Server can have enough large database size for
VLS. It supports databases’ size over a terabyte [31].
SQL Server is necessary to build several tables for VLS system, each
one for specific purpose. These tables are: traffic intersections table, vehicles
table, data online table, vehicle location table, black list table and authorized
users table.

3.3.2.1 Traffic Intersections Table
This table is constructed to define each intersection by a unique ID and each
intersection must have eight records (if the intersection has four roads) to
define all ways and antennas’ number that are installed in them.
The traffic intersections table has all the information about
intersections. It has the intersection ID, intersection number (from 0 to 7 if the
intersection has four roads), the region of the traffic intersection within the
city as (Baghdad/Al-Mansur), the IPs and Ports of the readers that are
installed in that intersection, the number of antenna on the road, the road is
going to any intersection ID (if possible) and the distance between them, and
the Username and Password of readers.
Besides, through the traffic intersections table, the system can define
the number of roads meeting in intersection, whether the intersection has
three, four, five or more roads. Also, if the road is one or two ways, that

37

depends on the number of records and the distribution of antennas in ways.
For example, five roads meeting in the intersection, VLS must have three
RFID readers and ten antennas, one of these readers have two antennas only
and they are numerated (from 0 to 9).

3.3.2.2 Vehicles Table
This table is used to register all vehicles’ information and properties. The
vehicles table contains the vehicle ID, the vehicle's owner, vehicle's type,
vehicle's description, vehicle's color, vehicle's model, the engine number of
vehicle and the tag ID that is attached in the vehicle.
The vehicle ID is a unique ID for each vehicle and consists of the city
that this vehicle is registered in, the number of this vehicle and the type of
number. The number type is P as Private (the plate’s color is white), L as
Load (the plate’s color is yellow), T as Taxi (the plate’s color is red) or Gov
as Government (the plate’s color is blue) and it takes the first character from
the name of any ministry.
The vehicle ID form is (city/number/type), for example:
(Baghdad/1234/P) the city is Baghdad, the number of the vehicle is 1234 and
the number type is Private that has white color. Other example:
(Gov/4321/H), H as Ministry of Higher Education and Scientific Research.

3.3.2.3 Data Online Table
This table is constructed to keep all the useful data received from readers. It
keeps all the information of tag recognition arrived online to CCS as tag ID,
the reader IP and Port that sent this tag, antenna number, the date and time of
detection.

38

3.3.2.4 Vehicle Location Table
A vehicle location table is an important table because it keeps all the inferred
information by middleware. It keeps information of vehicle path in all
intersections for each vehicle.
The vehicle location table records the vehicle ID that passed through
specific intersection ID, from-road number, to-road number, the date and the
entry time and the exit time from intersection.

3.3.2.5 Black List Vehicles Table
The black list table is used to enable the administrator to monitor set of
vehicles ID. Also, it will enable the administrator to add and delete vehicle’s
ID. The black list table has set of vehicles ID with their tags ID and the date
of the addition these vehicles in black list table.

3.3.2.6 Authorized Users Table
This table is constructed to secure and protect the information of VLS from
anyone unlicensed that may be penetrating VLS system and destroying a
system and database. The authorized users table consists of set of pairs as
administrators name and passwords.

3.4 Rifidi Platform

Rifidi is the premier open source simulator for RFID. It enables to
develop RFID system entirely with software components and remove the
dependency on hardware and infrastructure that RFID typically demands.
Furthermore, Rifidi is implemented in Java and it is possible to download the
source code and modify it.

39

Rifidi makes it possible to 'Virtualize' the RFID infrastructure with
software that defines RFID Readers, RFID Tags, and RFID Events that
behave like their real-life counterparts [32].
This Rifidi development project was born when a team of industrial
engineers tried to implement a client for 10’s a readers and they were stuck by
the complexity of this task. After discussing with many software development
companies and RFID experts they realized that RFID simulation tool would
be appreciable for testing applications. Since that, in March 2006, this team of
developers and RFID consultants started to work on this RFID simulation
project [32].
Rifidi is a complete RFID application platform; it allows the virtual
creation of RFID-based scenario while being sure that the software created for
this purpose will run as it is also in the real world. Indeed, Rifidi is a program
that simulates the reader/client interface of RFID reader. This means that a
client communicates with the Rifidi reader in the same way that it would
communicate with a real reader. For example, with the Alien reader, a client
would send messages to retrieve tag reads. The virtual Alien reader in Rifidi
Emulator responds to messages in the same way a real Alien reader does [33].
Rifidi team provided several software programs; each one has its
properties and design for specific case. The programs are Rifidi Edge server
and client, Rifidi Designer, Prototyper, Rifidi Emulator and Rifidi Tag
Streamer.
In VLS tests, two Alien ALR-9800 readers are considered that have
four antennas, as intersection readers and also several RFID tags are created.
The RFID tags are represented as vehicles.
The operations with Rifidi can be divided into two parts: connection
and send/receive data. In the first part, the connection is started between the
middleware and virtual readers. In fact, CCS will manage these readers and

40

will set the connections. In the second part, the virtual readers reply (Get
TagList) request by sending the tags list to CCS at each second.
In VLS, the both Rifidi Emulator and Rifidi Tag Streamer are used for
testing the system. Rifidi Emulator is used to test the middleware connection
protocols in communication performance with Alien ALR-9800 Reader and
to test sending the request (Get TagList) at each second and receive the reply
(the tags) from the reader.
Also, Rifidi Tag Streamer is used to test the robust of VLS middleware
in filtering the data that are received from readers at real-time and stored it in
data online table.

3.5 Roads and Traffic Intersections Simulation (RTIS)

Before introducing VLS in a real-life, the ability, functionality,
efficiency, and further effects have to be tested carefully. To evaluate the
improvements that can be achieved, the simulations have to be done.

3.5.1 The RTIS Architecture
A realistic simulation of roads and traffic intersections scenarios is needed.
Various parameters are needed to simulate the traffic, the application, and the
environment.
Traffic includes the physical movements of vehicles on an arbitrary
road network. Application simulation means the simulation of applications
that are to be integrated in real world vehicles. For this purpose, inner vehicle
interfaces have to be emulated to allow the application to interact with RFID
readers, as attached RFID tag on vehicles. The last part is the environment
simulation which includes the roads network with traffic intersections.
Also, TCP/IP server is built to simulate connection method in RTIS as

41

Alien ALR-9800 Enterprise RFID reader. The VLS connection with RTIS is
like the connection with real Alien readers.

3.5.2 The RTIS Scenario
To evaluate the effectiveness of the VLS and to identify potential problems, a
simulation scenario is selected as uncomplex as possible. For this reason, a
special region is assumed. This region has nine in-out ways and five traffic
intersections. One intersection is composed of three roads intersected and the
others are composed of four roads intersected. This region is chosen because
it provides a good road structure for VLS tests. The assumed region is called
Al-Mansur in VLS simulation.
The intersection ID is given to each intersection as sequence 146, 147,
…,150. Ten RFID readers are simulated, two readers to each intersection.
Each reader has IP and Port as sequence 10.20.30.22:20000,
10.20.30.23:20000,...., 10.20.30.31:20000, as shown in Fig. 3-5.
Seven vehicles are simulated and each vehicle is given specific vehicle
ID, tag ID and color. These vehicles move on the road network in random
path. Several routes are designed for each vehicle on road network. The
vehicle selects specific route which will pass through it by using random
function (that is supported in Visual Basic program). The random function
gives a random value, by depending on this value RTIS will decide the route
that the vehicle will pass.

42

Figure 3-5 The vehicles and roads network in RTIS

Specific car can be activated in the test to simplify tracking its
information in VLS by selecting the car check box, or activate all cars to test
the ability of VLS system. Also the speed of vehicles moving can be
controlled in RTIS.
The RTIS simulates RFID reader scanning and receiving tag ID from
vehicles. The virtual reader accumulates these data until it receives (Get
TagList) instruction from VLS. Then, it will send the gathered data to VLS in
CCS by TCP/IP server.
To illuminate the data sent to VLS, RTIS displays all data that are
gathered in the readers and will send them online to VLS in table. This table
displays the vehicle's tag ID that is captured by a reader, reader's IP and Port,
the number of antenna, the date, and the time of capturing tag ID, as shown in
Fig. 3-6.

43

Figure 3-6 The gathered data

Also, RTIS displays the meaning of these data that will be concluded in
the middleware of VLS as vehicle ID, intersection ID, from-road and to-road
in another table, as shown in Fig. 3-7.

Figure 3-7 The significance of the gathered data

The RTIS is designed for creating a scenario that is as real as possible.
All the unnecessary or unpredictable factors that can influence the results
such as side roads traffic or complex traffic light systems are avoided in order
to provide significant results.

44

3.6 RFID Readers Connection Protocols

Alien ALR-9800 Enterprise RFID Reader supports Serial port (RS-232,
DB-9 F) and TCP (LAN, RJ-45) connections. Serial connection is not useful
in VLS because the readers are distributed on large area. A TCP connection
provides DHCP, TCP/IP and SNMP network protocols.
When a CCS needs to connect to RFID reader in wide area network
such as the Internet, it uses a software component called a socket. The socket
opens the network connection for the middleware, allowing data to be sent
and read over the network. It is important to note that these sockets are
software, not hardware.
The socket interface is originally developed in UNIX to provide an
interface to the TCP/IP protocol suite. Internet socket, network socket or
socket is used for inter-process communication. A socket is one end of a two-
way communication link between two programs running on the network. A
socket address is the combination of an IP address and a port number [34].
Sockets are used to represent the connectivity between client and server. Fig.
3-8 shows the connection between client and server on specific port.

Figure 3-8 The connection between client and server on specific port [35]

Normally, a server runs on a specific host (RFID reader in VLS) and
has socket which is bound to a specific port number. The server waits from

45

client side for listening to the socket and makes a connection request. On the
client end (the middleware in VLS) the client knows the IP address of the
server and the port number of the server listening. Making a connection
request the client program tries to negotiate with the server program on the IP
address and port number. When connection is established between server and
client, client used that socket to communicate with server (read/write) [35].

3.7 The Methods of VLS Applications

VLS has several applications; these applications infer the useful
information from VLS data in database. The VLS applications display the
results in tables, figures or as reports. The following, the methods those used
in VLS applications.

3.7.1 Tracking Method for Vehicle Movement
The theoretical basis of virtual route tracking (VRT) algorithm is that the
interrogation range of RFID system is very short as compared to the distance
between readers. So, the position of the corresponding reader is used to stand
for the current position of tag (vehicle).

Figure 3-9 Principle of VRT algorithms [36]

In Fig. 3-9, the black points stand for RFID readers and the matrix is
RFID reader network (assume each reader or point represent one traffic

46

intersection). As the figure depicts, when a tag moves from reader (1, 1) to
reader (2, 2), the straight line between them is regarded as the track of the tag
by us. The virtual line (VRT) in figure is defined as the track of the tag. So,
the track in the figure is:
Track = Virtual Route: (1,1)→(2,2) → (2,3) → (1,4) → (2,5) → (3,5) → (4,4)
→ (4,3) → (3,2) → (4,1)
It is noted that, when a reader interrogates one tag, the next reader
interrogating it along the track must be adjacent to the previous reader. It is
obvious in Fig. 3-10 that the tag at (2, 3) cannot jump to (2, 5) directly
without activating reader (1, 4), (2, 4) or (3, 4). Therefore, VRT algorithm
must choose adjacent readers along the track [36].
The hierarchical structure of vehicle location over RFID reader network
is constructed and dynamically maintained while the vehicle is moving along.
Exploiting the inherent spatiotemporal locality of vehicle movements, this
hierarchy enables the system to conservatively update the vehicle location
information of moving vehicle only in adjacent traffic intersections [37].
Of course, real-world RFID reader network is impossible to place
readers so regular (exactly like a matrix) and previous figure here only depicts
fundamental of this algorithm theoretically.
In VLS, the VRT is used and the route is displayed in table or drawing
the path on region map. The vehicle path map application will be explained;
the system calls the vehicle ID, region of search, date and period of time from
GUI. The system will be connected with database for request that vehicle
passed through any traffic intersections IDs and also from where it is coming
and to where it is going. Then, the intersections ID organized as First,
Second…. etc. depending on sequence of time appeared in database. After the
system got all the information about that vehicle at that period of time, the
system would call graphics functions to draw the VRT of a vehicle on a map

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of this region. First draw from-road then draw to-road in each intersection, see
Fig 3-10. To recognize the direction of VRT, i.e. the beginning and the ending
of path, the system will draw the last intersection with blue color.

Figure 3-10 The flowchart for drawing the VRT on the map

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3.7.2 Estimation of Traffic Congestion
Reporting road traffic congestion can be a confusion task since there are
different algorithms measuring congestion. Typical users need a conciseness
and easiness to understand traffic report.
The normal traffic situation can be roughly categorized into two states,
open and congestion [38]. But it is observed that such a classification is not
enough to describe the traffic situation. Thus, in VLS three traffic patterns are
used to facilitate quickness and easiness to understand report [39]. Namely
Red (Traffic Jam), Yellow (Slow Moving), and Green (Free Flow) are defined
as the following:
1. Traffic Jam: there are large numbers of vehicles and almost all of the
vehicles run very slowly and it will be represented as red color.
2. Slow Moving: there are many vehicles and most of the vehicles run at
half speed and it will be represented as yellow color.
3. Free Flow: there are few vehicles and the vehicles run at normal speed
in the region of interest and it will be represented as green color.
To determine a congestion level, three steps are applied to estimate the
congestion status: 1) Compute the average time spent, 2) Compute the
average speed of vehicles and 3) Determining the final congestion level that is
compatible to the current system and ready to be reported to the public.
Next, each procedure will be explained in detail.

1. Compute the Average Time Spent
To compute the average time that is required to pass the road, the first
step the system gets the time from GUI. Then, the system goes back
five minutes past. Therewith it requests vehicles’ IDs that went out
from road within these five minutes. The next step, the system calls the
entry time to road for those vehicles. Then, it subtracts the exit time

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from entry time for each vehicle, see Fig. 3-11. The last step is
computing the time average via sum the spent time of all the vehicles
and divides it on the number of vehicles.
2. Compute the Average Speed of Vehicles
The system will compute the average speed of vehicles after it gets the
distance of the road from traffic intersections table [24]. The system
computes the average speed of vehicles via dividing the distance on
average time spent.
3. Determining the Congestion Level
After the system obtained the average speed of vehicles in road, the
next step, congestion levels are classified using speed into three levels:
red, yellow and green.
The VLS uses two classifications thresholds, γ and δ for adjusting
parameters of the algorithm, as follows [39]:
 Green level, if average speed is larger than or equal γ.
 Yellow level, if average speed is less than γ and larger than δ.
 Red level, if average speed is less than δ.
At the end, the user obtains from the system the average required time to pass
the road and the average speed of vehicles in the last five minutes as well as
estimating the traffic congestion level.

50

Figure 3-11 The flowchart for traffic congestion estimation

3.8 VLS Client Access

The VLS collects and stores the data in a database; these are private
data and can only be entered by an administrator. But some information in
VLS applications the user can access them by internet or cellular
telecommunications (GSM Mobile). The internet pages can be uploaded by
web servers such as Apache server, IIS server (Internet Information Server) or
any other web server.

51

Cellular telecommunications through GSM network must be supported
by modem device. Wireless modems are the modem devices that generate,
transmit or decode data from a cellular network for establishing
communication between the cellular network and the computer. Wireless
modems like other modem devices use serial communication to interface with
the computer (any microprocessor or microcontroller system) [40].
A GSM modem is a wireless modem that connects a computer to a
GSM network. Like a GSM mobile phone, a GSM modem requires a SIM
card in order to operate. Fig. 3-12 shows the established communication
between the cellular network and the computer via GSM modem.

Figure 3-12 GSM modem communications [40]

An external GSM modem is connected to a computer by a serial cable.
It is possible to make and receive phone calls and send text messages SMS
(Short Message Service).
AT commands must be used for establishing communication between
the GSM modem and the computer [40]. AT is the abbreviation for Attention,
AT commands are the set of commands that are specified for controlling a
GSM phone or modem and managing the SMS feature of GSM. The AT
commands are sent by the computer to the modem. The modem sends back an
Information Response, which is followed by a Result Code. The result code
tells about the successful execution of that command. If an error occurs in the

52

execution of a command, an error result code is returned by the modem and
the execution of the command line is terminated [41].
The mode of modem can be either text mode (available on some
modems) or Protocol Description Unit (PDU) mode. In text mode, headers
and body of the messages are given as separate parameters. PDU mode is
execution command sends message from a terminal equipment to the
network. The PDU shall be hexadecimal format and given in one line; phone
converts this coding into the actual octets of PDU [41].
In VLS, the Sony Ericsson Mobile Phone Modem AAD-3880020-BV
is used, that has the Sony Ericsson built-in modem software. The VLS modem
is programmed by AT commands with PDU format mode. It is used to
send/receive SMS message with the user (the driver).

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Chapter Four
Implementation of Vehicle Location System

4.1 Introduction

The VLS programs are implemented by applying the proposed methods
and algorithms that were explained in the previous chapter. These are
achieved using Visual Basic, ASP.Net Web Site and SQL Server
Management Studio. This chapter will discuss all parts of these programs and
how they can be used, as well as the chapter will discuss system applications,
SMS server and websites.

4.2 Vehicle Location System

VLS is composed of three parts which are main program, SMS server
and websites. The main program comprises the middleware, database
management and applications. The middleware controls the connection and
communication all RFID readers and database with CCS, as shown in Fig. 4-
1. The database management organizes the data and allows user to add,
update and modify records in tables. All VLS applications depend on the data
received from RFID readers.

54

Figure 4-1 The layout of the VLS environment

The implemented VLS, which includes main program of VLS, RTIS
and Wi-Fi system, as shown in Fig. 4-2.

Figure 4-2 The implemented VLS

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4.3 The Main Program of VLS

The main program is the CCS program; it is used to control RFID
readers, and manage the database and VLS applications. Fig. 4-3 shows the
main form of the VLS which has buttons to link all parts of the system. Each
button will be explained in the following subsections.

Figure 4-3 Main form of VLS

4.3.1 The VLS Security
After running the VLS program, the user name and password form appears as
shown in Fig. 4-4. This form is necessary to avoid accessing the VLS by an
unauthorized person. The administrator must know the user name and the
password. The default for both user name and password of VLS is (admin). If
anyone tries to use invalid user name and password, an error message will
appear. To let this program to be more flexible and more secure, the VLS has
the ability to change the password (see sec. 4.3.3).

Figure 4-4 The security form

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4.3.2 The VLS Tables
VLS system contains six tables in database (see sec. 4.4.2). Specific GUI
forms are designed to display the content of VLS tables.
The first table is the traffic intersections table, which defines all the
intersections and RFID readers which are installed in these intersections, as
shown in Fig. 4-5. The columns of usernames and passwords of RFID readers
are not displayed in this form because they will be displayed in RFID readers
table (see sec. 4.3.4). To enter the traffic intersections table form
Intersections button in main form of VLS must be pressed on. Also, to return
back the Back button should be pressed on.

Figure 4-5 Traffic intersections table

The vehicles table is an important table in the system because VLS
depends on it to recognize whether the received tag ID from reader belongs to
a vehicle or other object. This table contains all the information of vehicle and
its owner, as well as the ID of tag that is attached in vehicle. This table must
contain the information about all the vehicles in different cities. GUI of

57

vehicles table as shown in Fig. 4-6 . To open this form, Vehicles button in the
main form of VLS should be pressed.

Figure 4-6 Vehicles table

The data online table keeps all tags IDs received from readers. This
table is used when there is loss in some information or tag ID is not detected,
e.g. if the vehicle is detected on entering the intersection and VLS could not
detect it on leaving the intersection for unknown reason. This vehicle ID is
not saved in the vehicle location table (see sec. 4.4.1), data online table will
be used to prove a vehicle passed through that intersection at that date and
time. Via clicking on Data Online button in the VLS form, the GUI of data
online table will show, as shown in Fig. 4-7.

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Figure 4-7 Data online table

In VLS project, all the gathered data must be analyzed and filtered. At
the end all concluded information will be saved in vehicle location table. All
the paths of vehicles are stored in this table and the date and time of in and
out. To access the GUI of the vehicle location table, Vehicle Location button
should be clicked on, as shown in Fig. 4-8.

Figure 4-8 Vehicle location table

59

The form in Fig. 4-9 shows the black list vehicles table and two buttons
for adding and deleting vehicle ID.

Figure 4-9 Black list vehicles table

The black list vehicles table is used to monitor in real time the illegal
and the stolen vehicles by adding vehicle ID to the table. Fig. 4-10 shows the
vehicle that is detected in real time.

Figure 4-10 The vehicle which in black list is detected

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To delete any vehicle ID from black list table, Delete Vehicle button
must be clicked on. Then, text box will appear to write the ID of vehicle that
needs elimination from black list, as shown in Fig. 4-11.

Figure 4-11 Deleting vehicle ID from black list table

By clicking on Tables Update button in the main VLS form, the form
in Fig. 4-12 will appear. This form gives the ability to the user to add, update
and modify traffic intersections and vehicles tables.

Figure 4-12 Tables update form

61

To update traffic intersections table, Intersections button should be
selected. Through this form the user can add, delete and modify records of
intersections table via using Navigator Tool, as shown in Fig. 4-13. Return
button is used to return to tables update form.

Add New Records Delete Record Save All Updates

Figure 4-13 Update of traffic intersections table

By selecting Vehicles button, the update form of vehicles table will be
opened, as shown in Fig. 4-14.

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Figure 4-14 Update of vehicles table

4.3.3 Setting Database and Authorization
Via clicking on Setting button in the main form of VLS, the form in Fig. 4-15
will appear. This is an important form because it can store the database as
archive and clean the tables that are automatically and continuously update
(i.e. Data Online and Vehicle Location Tables).

Figure 4-15 Setting database and authorization

63

By clicking on Backup Database button, the "Save File" dialog box
will appear to specify the place to store backup database file. After backup
database file is stored, a message (Backup database is created successfully)
will be displayed.
By clicking on Backup and Cleaning button, the VLS will create
backup database and clean data online and vehicle location tables. After
completing the backup and cleaning tables, the message in Fig. 4-16 will be
shown.

Figure 4-16 A message of cleaning tables successfully

By clicking Restore Database button, the monition message (The
restoring operation will delete the current data in database) will be shown, as
shown in Fig. 4-17. Then, by clicking on yes button, the "Open File" dialog
box will be appeared to specify place of backup file of database. The
restoration operation may need few minutes to be completed.

64

Figure 4-17 Restore database

To allow the program to be more flexible and more secure, VLS gives
the ability for the administrator to change the password by clicking on
Change Password button, then Fig. 4-18 will be shown. The old and new
password must be entered in the form. After pressing the Save Change
button, a message (Changing Password Successfully) will appear.

Figure 4-18 Password change form

65

4.3.4 The Connection with RFID Readers
This is a presentation form of the middleware. By this form RFID readers can
be connected or disconnected. Also, the performance of readers can be
managed and monitored in real-time. As well as monitoring the numbers of
tags that are received and compared with the number of the tags that are
filtered and stored in data online table. To enter this form, Connect To
Readers button in main form of VLS should be clicked on, as shown in Fig.
4-19.

Figure 4-19 The connection form with RFID readers

To connect with reader, the administrator must enter IP, Port, User
Name and Password of reader and select its check box (as shown in Fig. 4-
19). Then, by clicking on Connect button, the system will initialize the
connection and display if the connection is successful or failed. The
disconnection of any reader is achieved by selecting its check box and click
on Disconnect button. If this reader is already disconnected a monition
message will be displayed.

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When VLS project is running, if any reader's connection is shut
irregularly, the VLS will display a warning message as shown in Fig. 4-20.

Figure 4-20 The connection shutdown irregularly

The RFID Readers button will open a new form to display the
information of traffic intersections' readers. These are subset of information
that is stored in traffic intersections table, as shown in Fig. 4-21.

Figure 4-21 RFID readers table

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The Conn. Show button in Fig. 4-20 will display a new form to show
the connection stream, as shown in Fig. 4-22

Figure 4-22 The connection stream

Also, the Display button will show statistics for the numbers of tags
that are received and the numbers of the tags that are filtered and stored in
data online table.

4.3.5 The Traffic Congestion Appraisal
The VLS system supports some applications for the data that are gathered and
analyzed. Most of these applications depend on vehicle location table. The
traffic congestion appraisal is one of them. This application can estimate the
congestion in two conditions: along the street or within the intersection.
Via click on Intersection Status button in the main form of VLS, the
GUI of intersection congestion appraisal will be shown, as shown in Fig. 4-

68

23. Appraisal of traffic intersections congestion is used to estimate the
required time to cross the intersection. It calculates the average of the required
time to cross the distance between the antenna of entry and the antenna of
exit. This application uses only the first step of Estimation of Traffic
Congestion method (see sec. 4.8.2).
The traffic intersection ID should be entered in its specific field. The
congestion can be appraised for the time being (default) or at previous date
and time by selecting its button then specifying the date and time.
The suggested system uses α and β criteria to estimate the status of
congestion in intersection. The system enables α and β to be changed by the
user, via click on Setting button that activate its texts boxes. α and β are the
time range that are required (in seconds) to cross the intersection. By clicking
on Congestion Status button, the system will compute and display results as
the number of vehicles passed through the intersection in the last five
minutes, average of the required time to pass this intersection (in seconds) and
the intersection congestion status as Free Flow, Slow Moving or Traffic Jam.

Figure 4-23 The traffic intersections congestion appraisal

69

Via click on Street Status button in main form of VLS, the form in Fig.
4-24 will be appeared. The street congestion appraisal is very important
application of VLS. By this application the street congestion status can be
estimated in real-time.
The user must specify the street and the direction of traffic. This is
done by giving the ID of the intersections i.e. from-intersection to-
intersection. The time must be specified at the present time (default) or on the
previous date and time by selecting its button then specifying the date and
time. In this application, the system uses γ and δ criteria to decide status of
traffic congestion in street, γ and δ are the range of vehicles’ speed criteria (in
km/Hr) that pass through street. VLS system enables the user to change γ and
δ, via click on Setting button that activate its texts boxes.

Figure 4-24 The street traffic congestion appraisal

This application uses all steps in the method of Estimation of Traffic
Congestion. By clicking on Congestion Status button, the system will display
the required time average to pass that street, the speed average of vehicles that
passed through the street and the street traffic congestion status.

70

4.3.6 The Vehicles Locations Discovery
VLS system provides vehicles locations discovery application. This
application is used to detect the intersections where the vehicle passes through
them, also the time and the position of entry and exit within intersections.
The user ought to enter vehicle ID and specify the date and the period
of time. Then by clicking on Locating Vehicle button, the VLS will search for
that ID in this period and display the result in table, as shown in Fig. 4-25.

Figure 4-25 The vehicles locations discovery

4.3.7 The Vehicle Path Map
Vehicle path map is an application provided by VLS, it is used to draw the
route of vehicles on map of the region. This service uses The Tracking
Method for Vehicle Movement (see sec. 4.8.1).
First, the user selects the region of his search. VLS will immediately
load the map of this region. Second, the user enters vehicle ID and specifies
the date and the period of time for tracking. By clicking on Path button, the
system will draw the route of vehicle on map in red color, and the last

71

intersection the vehicle passed in will be drawn in blue color. This is done for
recognizing the beginning and the ending of the route, as shown in Fig. 4-26.
The thin violet rectangular is drawn to identify the search region on map.
Clean button must be clicked to draw route for another vehicle.

Figure 4-26 The vehicle path map

4.3.8 The Intersection Monitoring and Tracking Vehicle Color
Through intersection monitoring application certain intersection can be
monitored in terms of the number of vehicles that are passed, their IDs and
where they have come from, where to go, the time of entry and exit from the
intersection.
The user enters the ID of the intersection, limits the time and date.
Then, by pressing the Monitoring Intersection button, the system will then
show the number of vehicles that have passed during that time period, as well
as the ID of vehicles, where they have come from and where to go and the
time of entry and exit, as shown in Fig. 4-27.

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RFID based design for vehicle location system

RFID based design for vehicle location system

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