1. SENSOR (RFID) NETWORKS AND COMPLEX
MANUFACTURING SYSTEMS MONITORING
(COMMSENS): LABORATORY FOR RFID
RESEARCH
Satish Bukkapatnam
Associate Professor
Oklahoma State University
Stillwater OK
REPORT OF WORK CONDUCTED UNDER THE AEGIS OF CELDi
STRATEGIC RESEARCH GRANT 2005: “EXPERIMENTAL TEST
BED FOR PERFORMANCE EVALUATION OF RFID SYSTEMS”
Contributing Members:
Jayjeet M. Govardhan
Sharethram Hariharan
Vignesh Rajamani
Brandon Gardner
Andrew Contreras
Oklahoma State University
Stillwater OK

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TABLE OF CONTENTS
EXECUTIVE SUMMARY ....................................................................................................................3
SECTION 1: INTRODUCTION...........................................................................................................5
SECTION 2: GUIDELINES FOR RFID SYSTEM DESIGN AND DEPLOYMENT PART 1:
TAG AND READER DESIGN GUIDELINES..................................................................................10
SECTION 3: GUIDELINES FOR RFID SYSTEM DESIGN AND DEPLOYMENT PART 2:
USE CASE MODEL AND ARCHITECTURE OF SAVANT..........................................................28
SECTION 4: SUMMARY OF BEST INDUSTRY PRACTICES & DEVELOPMENTS IN RFID
SYSTEMS AND THEIR EXPERIMENTAL INVESTIGATION ...................................................45
SECTION 5: STATISTICAL ANALYSIS AND DESIGN OF RFID SYSTEMS FOR
MONITORING VEHICLE INGRESS/EGRESS IN WAREHOUSE ENVIRONMENTS............77

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Executive Summary
In the late fall of 2004, CELDi approved our proposal on developing
"Experimental test bed for performance evaluation of RFID systems." This grant has
spurred the development of a laboratory for Sensor (RFID) Networks and Complex
Systems Monitoring (COMMSENS) research. This lab is spread over 1000 sq. ft.
space in the Advanced Technology Research Center (ATRC) of Oklahoma State
University. Our initial efforts under this grant were focused on procuring the
instrumentation to create an experimental test bay for RFID systems performance
assessment. The test bay consisted of AWID and Alien readers and 200 passive
tags. Using this test platform, we have successfully validated a systematic approach,
based on combining statistical analysis and Electromagnetic principles, for robust
design of RFID systems. Publications on the following three topics have emerged as
a result of our investigations:
1. Development of Guidelines for Front/Backend Design of an RFID System,
2. Best Industry Practices in RFID System Deployment, and
3. Statistical Analysis and Design of RFID Systems for Monitoring Vehicle
Ingress/Egress in Warehouse Environments
Furthermore, in order to facilitate a broad dissemination of research undertaken in the
COMMSENS on RFID systems and sensor technologies, a new course on RFID
applications in manufacturing systems was created in Spring 2005. This course, open
to both undergraduates and graduate students at OSU, is one of the first ones offered
on RFID applications in production systems. Collaborating with University of
Nebraska, we have offered a 6-hour tutorial on RFID fundamentals and Applications
at CELDi pre-conference event during Spring 2005. The course content for the next
offering of RFID course in the spring of 2005 has been re-designed taking into
account an increase in enrollment levels and the need to include the developments that
have taken place since the last offering of the course. In fact, many developments
have taken place in the recent times that can lead the industries towards efficient
adoption of RF and sensor technologies. We strongly feel that more background
preparation is necessary in order to bolster the exponential growth of these
technologies as well as their adoption in the real world applications.

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A research is never complete or successful unless it can reach the end users,
namely, the industries. Towards this end, we have initiated partnership projects with
GM, FAA Logistics Center, and Oklahoma Department of Transportation. This
allows us to share our knowledge of RFID systems and sensor technologies with, in
some sense, the business world. We have also initiated dialogues with SUN RFID
Center, and RFID component vendors, including manufactures like Alien and AWID,
RFID consultants, and academic institutions, particularly, the University of Nebraska.
We have also been successful in attracting 12 students to participate in our
research activities. Their qualification levels range from undergraduate to graduate
standing (M.S. to Ph.D. level) with diverse backgrounds such as from mathematics,
mechanical and aerospace engineering, industrial engineering, and electrical
engineering. Their passion for advancing RFID systems and sensor technologies is a
common thread that binds them all. COMMSENS lab research conducted under the
aegis of CELDi, thus, has had a positive impact on the students involved as well as on
our knowledge and understanding of RFID systems and sensor technologies.

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Section 1: Introduction
1.1 Background
The Sensor Networks (RFID) and Complex Manufacturing Systems
Monitoring Research (COMMSENS) lab was established in 2004 at the Advanced
Research Center (ATRC) of Oklahoma State University in Stillwater, OK. The
COMMSENS Lab facilities are spread over 1000 square feet at the ATRC for hosting
test-beds for RFID and RF Sensing research. Lab facilities include antennae and
readers from Alien and AWID, as well as 200 passive tags of various specifications.
The lab also features RF sensing devices like motes from moteiv® (IEEE 802.15.4
compliant) for wireless mesh networking. All RFID information is processed in a
Linux server that uses the SUN JAVA RFID software package with an Application
Server and Enterprise Manager. Oracle 10i is used as the database to store
information collected from our experiments. New experimental test bays with the
latest Gen 2 specific hardware and software are being set up for the future
applications.
1.2 Mission
The mission of the lab is to study the principles of monitoring real world
complex systems by harnessing information from a network of wired and wireless
sensors. Such applications include various complex manufacturing machines,
processes, enterprises, consumer products, and infrastructures like bridges, pipelines
and railroads. Furthermore, we are attempting to harness large amounts of sensor data
to bring substantial improvements to the design and operations, particular in quality
and integrity assurance, of these engineering systems, which include many precision
manufacturing machines and processes, the Internet, supply networks and
infrastructure and lifelines systems. Overall, the objectives of our research are the
following:
• Study the origins of complicated patterns in sensor signals from
manufacturing machines, processes, and specific infrastructure and lifeline
systems

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• Derive theory and methods to capture the dynamics underlying these signals
for quality and integrity monitoring
1.3 Accomplishments
The following is a list of accomplishments and awards received as a result of
COMMSENS research:
• The lab efforts have received support from NSF, CELDi (the nation’s largest
Industry-University consortium focused on logistics), General Motors, FAA,
and the US Department of Transportation to the tune of $0.9M during 2004-
05
• A new course focusing on RFID system applications in manufacturing and
engineering systems (one of the firsts of its kind in Industrial Engineering)
offered in spring 2005
• A systematic statistical approach for experimental design of an RFID system
developed. Also the research has yielded new principles for harnessing
information on the complex (nonlinear and stochastic) nature of the process
underlying signals from RFID and other sensor networks
• The research has yielded 25+ journal papers and 20+ publications in refereed
conference proceedings apart from being the basis for 3 PhD theses
• Currently 16 students including 3 PhD, 5 MS thesis, 2 MS creative
component, and 3 undergrad students take part in the lab activities (these
include 3 members from underrepresented groups)
1.4 Education
Accompanying the research at the COMMSENS lab are several educational
components, which include:
• A new course on RFID Applications in Manufacturing Systems offered in
Spring 2005
• Guest lectures offered by several prominent industry speakers and
implementers of RFID to share ideas and discuss technical issues
surrounding RFID; thus supplementing course material with practical aspects
• Field trip to SUN-RFID Testing Center in Texas was organized where pallet
level and item level readability in conveyor environment was demonstrated

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• White papers that describe the quantitative and qualitative aspects of
deploying RFID in a given environment have been published ─ papers
detailing recent experiments are forthcoming
• A 6 hour tutorial on RFID fundamentals and applications offered to industry
participants as part of 2005 CELDi pre-conference event
1.5 Capabilities
Capabilities and resources of the COMMSENS lab are the following:
• Test bays and a statistical approach for RFID system design and deployment
• New design method based on combining statistical and electromagnetism
principles to screen parameters affecting an RFID system performance
• Framework to undertake customized ROI studies
• RFID /RF sensor deployment, instrumentation and integration studies for
quality, integrity, performance monitoring and surveillance
• Simulation based evaluation of decision enrichment using RFID/RF sensor
information
• A new simulation approach based on continuous flow dynamics for fast
evaluation of system performance
• Quality and integrity monitoring of complex machines and processes
including precision machining and other manufacturing operations
• Sensor-based health monitoring of complex structures for condition-based
maintenance and Integrity assurance
• Characterization of nonlinear stochastic dynamics underlying in large
complex systems including various manufacturing machine operations, smart
material and structural systems, large supply and transportation networks,
and the Internet. See lab photographs below

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1.6 People
The people involved in COMMSENS research come from a variety of
backgrounds such as mathematics, industrial, mechanical, and electrical engineering.
The following is a list of the people involved with COMMSENS research at OSU:
• Satish T. S. Bukkapatnam, Ph.D., Associate Professor
Topic: Overall Project Supervision
• Brandon Gardner, Graduate Student, Dept. IEM
Topic: Financial Model of RFID Systems
• Sharethram Hariharan, Graduate Student, Dept. IEM
Topic: Improved Decision Making in Business Process by the use of Markov
Decision Process
• Vignesh Rajamani, Graduate Student, Dept. EE
Topic: EM Theory Applications in Antennae and RFID Systems Design
Foam Metal Liquids
Linux
SystemHigh Tag
Density
Reader & Antenna
Setup
Bubble
Wrap
EDS
Reader & Antenna
setup

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• Jayjeet Govardhan, Graduate Student, Dept. IEM
Topic: Technical Aspects of RFID System Design
• Alicia Jones, Undergraduate Student, Dept. IEM
Topic: RFID Sensor Documentation
• Andrew Contreras, Undergraduate Student, Dept. MAE
Topic: Gen 2 System Analysis
• Amjad Awawdeh, Graduate Student, Graduate Student, Dept. EE
Topic: RFID Sensor Applications
• Tanay Bapat, Graduate Student, Dept. IEM
Topic: Documentation of RFID Coursework
• Randy Clark, Undergraduate Student, Dept. of IEM
Topic: RFID front-end design
• Gerardo Myrin, Undergraduate student, Dept. of IEM
Topic: RFID front-end design
• Vipul Navale, Graduate student, Dept. of IEM
Topic: RFID front-end design
• Chetan Yadati, Graduate Student, Dept. of IEM
Topic: Implementation of Use Case Analysis in RFID middleware
development
1.7 Organization of Report
This report is divided in to four main components:
I. Guidelines for RFID System Design and Deployment Part 1: Tag and Reader
Design Guidelines
II. Guidelines for RFID System Design and Deployment Part 2: Use Case Model
and Architecture of Savant
III. Summary of Best Industry Practices & Developments in RFID systems and
their experimental investigation
IV. Statistical Analysis and Design of RFID Systems for Monitoring Vehicle
Ingress/Egress in Warehouse Environments

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Section 2: Guidelines for RFID System Design and
Deployment Part 1: Tag and Reader Design Guidelines
Summary
The design and selection of appropriate RFID system components is usually
among the first steps in the implementation of an RFID system. Over twenty
parameters govern the performance of an RFID system in a given environment. This
document is the first of a two part series that guidelines for developing a basic RFID
system for a particular application and introduces the relevant RFID fundamentals
concepts.
2.1 Introduction to RFID
Radio frequency identification (RFID) is a generic term used to describe the
technologies that harness radio-frequency waves to transfer data between a reader and
a tag to identify, categorize and track objects. RFID is fast, reliable, and does not
require physical sight or contact between reader and the tagged object.
An RFID system consists of tags (also known as transponders), readers and a
computing infrastructure for storing and analyzing the data received from the reader.
A transponder is usually a memory device (e.g. Electrically Erasable Programmable
Read-only Memory EEPROM) fitted on the object to be identified. It contains
information to uniquely identify an object. The reader is capable of generating,
receiving, demodulating and deciphering RF signals. As summarized in Figure 1, the
reader sends RF signal into the environment. As soon as a tag comes into the reader’s
RF electromagnetic field, the tag circuit sends signals back to the reader, thus
identifying the object. This identification technology can be used for real time object
tracking, goods and/or asset management, etc.
The tags can be classified into various types depending on whether they are
active or passive, read only and/or writable, etc. The readers too have different
specifications like frequency, type of data transmission method, etc. The selection of
the tag and reader attributes strongly impact the performance of the RFID system.

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Figure 1: Components of an RFID System [1]
2.2 RFID Tag Selection Guide
The selection of RFID tag plays critical role in the successful deployment of
an RFID system. The appropriate tag should conform to the required functionality
expected in the given field, application, environmental conditions, and government’s
regulations on the frequency use.
2.2.1 Parameters considered in Tag Selection:
Following are the seven major parameters [2] considered in the process of tag
selection (See Figure 2):
1. Application Requirements
2. Read Range
3. Frequency
4. Functionality
5. Environmental Conditions
6. Form Factor
7. Standard Compliance EPC/ISO

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Figure 2: Parameters Affecting Tag Selection
2.2.1.1 Application Requirements
RFID system applications include dock door reading, asset management, and
transportation, inventory management in warehouses, conveyor reading, and point of
sale reading, handheld mobile reading and smart identification card systems. These
are the typical examples based on our observation. [The different applications and
estimated growth of the global market for RFID systems can be seen in Figure 3].The
application determines where and what objects are to be tracked. The application-
imposed constraints, ultimately determine the choice of the read range.
Figure 3: Estimated growth of global market for RFID systems[3]

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2.2.1.2 Read Range
Read Range is the farthest distance between reader and tag at which reader can
read the tag. Determinants of read range include frequency of operation,
Electromagnetic Interference (EMI) levels, power of the reader (which is usually
limited by Federal mandates), tag functionality, size of stored data, read time, relative
velocity between the tagged object and the reader, and antenna design. The major
factor among these is the frequency of operation based on the read range requirement
2.2.1.3 Frequency Range
The frequency ranges are categorized as Low (LF), High (HF), Ultra High
(UHF) and Microwave frequency. The choice of frequency range depends upon the
application / performance requirements and the regulatory requirements. The actual
frequency values vary as per geographical regions. For US and Canada, 13.56 MHz is
considered as HF and UHF ranges from 902 MHz-928MHz. This variation in actual
frequency range values for geographical regions is a hindrance in developing a unique
RFID system that can be deployed worldwide. Refer table for more details [4], [5]

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Table 1: Geographical Variation in Frequency Ranges
Frequency
Zones
Low
Frequency(LF)
High
Frequency(HF)
Ultra High
Frequency(UHF)
Microwave
US and
Canada
125 - 134 KHz 13.56 MHz 902 - 928 MHz 2.4 - 2.48 GHz
Europe 125 - 134 KHz 13.56 MHz 868 - 870 MHz 2.4 - 2.48 GHz
Japan 125 - 134 KHz 13.56 MHz 950 - 956 MHz 2.4 - 2.48 GHz
2.2.1.4 Functionality
Based on functionalities, tags may be classified as passive, active and semi-
passive. Passive tags are not supported with batteries, but they are powered by the energy
supplied by reader field. Passive tags are cost effective and used in supply chain for
identifying and tracking objects. Active tags are battery powered. See Figure 4. They can
be used for long-range applications. Semi-passive tags are supported with batteries, but
they are activated by the reader field. These tags are used for capturing additional details
like temperature, humidity, etc.
Figure 4: Tag Functionality
2.2.1.5 Form Factor
Form factor determines the size and shape of a tag. Generally, larger tags provide
better range performance over tags with smaller form factors. The trade off analysis

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between the size of the tag and required range performance must be carried out while
selecting tag for particular application. See Figure 5.
Figure 5: RFID system classification based on tag functionality
2.2.1.6 Environmental Conditions
Environmental conditions and materials near RFID systems can affect RF field
parameters like reflectivity/refractivity, absorptive and dielectric properties (detuning).
Hence, tag performance is dependant upon materials near the tag and environmental
conditions like temperature, humidity, etc. Different frequency ranges experience
different degree of effects due to above materials. For example, the attenuation of
reflectivity increases with the frequency. The suitable frequency range and tags should be
chosen in order to minimize these effects.
Table 2: Effect of Materials on RF field
Material Effect on RF field
Cardboard
Absorption (moisture), Detuning
(dielectric)
Conductive liquids Absorption
Plastics Detuning (dielectric)
Metals Reflection
Groups of cans
Complex effects (lenses, filters),
Reflection
Human body /
animals
Absorption, Detuning (dielectric),
Reflection

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2.2.1.7 RFID Standard Compliance
In order to avoid interferences from other RF applications like electric and radio
equipments and to achieve interpretability between different tags and readers, RFID
system standards are being developed. These standards deal with air-interface protocol,
data content, conformance with regulatory requirements, and application. Two major
standards available today are Electronic Product Code (EPC) Global and ISO/IEC
standards.
• EPC Standards
EPC has specified standards for tag data content, communication between tag &
reader (air-interface protocols), reader protocols, Savant specifications, Physical Mark-up
language (PML) specifications, and Object Naming Service (ONS) specifications for HF
and UHF ranges. There are two versions of these standards. Version 1 is already in use
and version 2(Generation 2) is ratified and going to be adopted in near future. As per this
standard, data is stored on the tag, in the format as shown in Figure 6.
Version 1 is already in use and version 2(Generation 2) is ratified and going to be
adopted in near future. Companies like Texas Instruments, Impinj, Philips
Semiconductors, Alien Technology, Symbol Technologies and Intermec Technologies
have announced their plans to manufacture Gen 2 tags.
Figure 6:Tag Data Partition

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Table 3: Tag Classification based on EPC Global Protocol [4]
EPC
Class
Description Functionality Remarks
0 Read Only Passive tags
Data can be written only once
during tag manufacturing and
read many times
1
Write Once and
Read only
Passive tags
Data can be written only once
by tag manufacturer or user and
read many times
2 Read/Write Passive tags
User can read/write data many
times
3 Read/Write
Semi-passive
tags
Can be coupled with on board
sensors for capturing parameters
like temperatures, pressure, etc.
4 Read/Write Active tags
Can be coupled with on board
sensors and act as radio wave
transmitter to communicate with
reader
• ISO/IEC 18000 Series
ISO & IEC have established Joint Technical Committee to address technology
standards. Within JTC -1, Subcommittee 31, Work Group 4 deals with RFID. ISO
15693 and ISO 18000 series provide air interface standards for communication
between tag-reader and reader-tag at LF, HF, UHF and microwave frequencies.
These standards also specify parameters like data encoding rules, data
transmission rates, types of signal modulations and anti-collision protocols [6],
[7].
• 18000-1 Part 1 - Generic Parameters for the Air Interface for Globally Accepted
Frequencies
• 18000-2 Part 2 - Parameters for Air Interface Communications below 135 KHz
18000-3 Part 3 - Parameters for Air Interface Communications at 13.56 MHz

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• 18000-4 Part 4 - Parameters for Air Interface Communications at 2.45 GHz
• 18000-5 Part 5 - Parameters for Air Interface Communications at 5.8 GHz
(Withdrawn)
• 18000-6 Part 6 - Parameters for Air Interface Communications at 860 to 930 MHz
• 18000-7 Part 7 - Parameters for Air Interface Communications at 433 MHz
Efforts are initiated to form a unique standard that will avail a common platform
for widespread adoption of RFID technology all over the world.
2.3 Market Survey
Below is the summary of available tags and tag manufacturers in today’s market.
This summary of various tag manufacturers, tag functionalities and their features will
help user to select appropriate tag for his application.
Table 4: RFID Tag Market Survey
Manufacturer Model Frequency Functionality Standard Remark
ALL-9238,
ALL-9250,
ALL-9254
UHF
(902-928
MHz)
Passive and
64 bit
EPC
Global
Class 1
General purpose
item tracking,
suitable in
metallic
environment
Alien
Technology [8]
ALL-9338,
ALL-9354,
ALL-9334
UHF
(902-928
MHz)
Passive and
96 bit
EPC
Global
Class1
General purpose
item tracking
Dual Dipole
UHF
(902-928
MHz)
Passive
112,128 bits
EPC
Global
Class 0
Matrics
/Symbol
Technologies
[9]
Single
Dipole
UHF
(902-928
MHz)
Passive
112,128 bits
EPC
Global
Class 0
General labeling,
carton & pallet
labeling, and
pharmaceutical
labeling

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Manufacturer Model Frequency Functionality Standard Remark
Hitachi [10] Mu-chip 13.56 MHz
Passive and
128 bit
EPC
Global
Class 1
0.4mm x 0.4mm
x 0.060 mm size.
Can be used in
currency notes for
authentication
Tire Tag
Insert
UHF
869 /915
MHz
Passive Class 1
Used in tire
tagging. Typical
Applications
include work in
process (WIP),
quality control
Container
Tag
UHF
915 MHz
Passive Class 1
Pallet, carton and
container tracking
Intermec
Technologies
[11]
CIB
Meander
Free Space
Insert
2.45 GHz Passive Class1
Electronic Article
Surveillance tags,
and inventory
management

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2.4 RFID Reader Selection Guide
A reader is critical to a successful deployment of a RFID system. The appropriate
reader should fit with required functionality based on the application, environment
conditions and country’s frequency norms. This section presents the criteria for reader
selection.
2.4.1 RFID Reader Selection Guide
Following are major parameters considered in the process of reader selection:
1. Application Requirement
2. Frequency Range
3. Read/Write Range
4. Functionality of Tag
5. Standard EPC/ISO Air Interface
Figure 7: Parameters Affecting Reader Selection

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2.4.1.1 Application Requirement
The shape, size and functionality of a reader change according to the application
of the RFID system. Some of the common RFID systems are conveyor reading, dock
door reading, forklift reading, mobile reading etc.
2.4.1.2 Frequency Range
A suitable reader, for a given application, can be selected to match the frequency
range chosen (LF, HF, UHF or Microwave). Multi-frequency readers can be chosen if the
application requires using both short as well as long read/write ranges.
2.4.1.3 Read/Write Range
Read range is based on the frequency chosen, functionality of the tag and power
of the reader. Write range is the distance from which a reader can write tags. This range
is usually 70% of read range.
2.4.1.4 Functionality of Tag
Active and passive tags talk to reader using different air-interface protocols.
Hence, reader should support the functionality of tag. A multi-protocol reader which
supports different protocols is seen as the best solution and is quiet popular in today’s
market.
2.4.1.5 Air Interface Protocol
Reader should support the air-interface specifications provided by either EPC or
ISO standards. The reader and tag should comply with these standards. Some readers can
support EPC as well as ISO standard protocols and these are the most popular ones in the
market.
2.4.1.6 Other Factors
Other factors like the number of tags read per second, interface to the host and
anti-collision (Tag collision and Reader collision) are also important. Based on need of
application, suitable parameters can be chosen for the selection of the reader. Anti-
collision requirement can be the most demanding feature. Reader should recognize

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uniquely the identity of tags lying in the range of the reader. ISO and EPC protocols
define anti-collision implementations.
2.5 Market Survey
Below is the summary of readers and their manufacturers in today’s market.
Table 5: RFID Reader Market Survey
Manufacturer Model Frequency Type Standard Remark
ALR-
9780
UHF
902-928
MHz
Fixed
EPC Global
Class1
Compatible with any LAN
network, perfect match for
applications where high-
speed, highly reliable
reads are required.
Alien
Technology [8]
ALR-
9640
UHF
902-928
MHz
Fixed
EPC Global
Class1
Low-cost, flexible
industrial reader, The
reader electronics and
antenna reside in a single
package, eliminating
external antenna cables,
resulting in a simple and
inexpensive installation.
Matrics/Symbol
Tech [9]
AR-400
UHF
902-928
MHz
Fixed
EPC Class 0
and Class 1
Multiprotocol reader-
Supports all EPC-
compliant passive RFID
tags, Allows dynamic data
updates for broader
application support and
provides flexibility in tag
usage, EPC Generation 2
Upgradeable

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Manufacturer Model Frequency Type Standard Remark
Samsys
Technologies
[12]
MP9320
MP9310
UHF
902-928
MHz
Fixed
EPC Class
0, 0+, Class
1,
ISO18000-
6A, 6B, 6B
"fast",
Philips U-
code 1.19,
1.19 "fast",
Intermec
Intellitag,
EM Marin
4022, 4222,
4223
Flexibility in supporting
multiple tag protocols,
multi-regional regulatory
compliance, and
programmability for a
multitude of EPC
applications environments
Configurable for North
America FCC (902-928
MHz) and European ETSI
(865-869 MHz) regulatory
environments

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2.6 Boilerplate for RFID Component Selection of a Typical
Warehouse
2.6.1 Warehouse Operations
RFID technology has great potential in streamlining warehouse operations to meet
the dynamic market demand. We have developed RFID tag and reader selection guide
which can be used to configure the RFID system for particular applications. This section
contains a brief discussion of the various warehouse operations and how the RFID tag-
reader selection guide can be used to configure RFID system for these operations.
2.6.2 Assumptions
In preparing the above boilerplate, the following assumptions are made:
1. The warehouse under consideration is used only for consumer goods.
2. Case and pallet level tagging are the only ways to deploy RFID tags on the
products. (Item level tagging is not considered).
The key operations in warehouse are:
1. Receiving
2. Inspection
3. Bulk Storage / Cross Docking
4. Order Picking and Sorting
5. Shipping
Figure 8: Material Flows in a Warehouse

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The above operations can be defined briefly, as follows and depicted in Figure 8
and explained below:
1. Receiving
Incoming truck is identified and routed to appropriate receiving dock. At
receiving dock, products (raw material, semi-finished, or finished) are unloaded.
2. Inspection
The quality (mostly visual inspection for damage detection of cartons) and
quantity of received products is assured as per requirement. The faulty products are
separated.
3. Cross Docking
Cross docking is the process of unloading material from one truck or trailer and
loading it to outbound truck or trailer without storing it in warehouse.
4. Bulk Storage
Received products are identified and routed to appropriate storage location in
warehouse. Generally, the products are stored in carousals, racks or on pallets.
5. Order Picking and Sorting
Once the order is received, the products are picked in correct quantity. Once order
is filled, the products are routed to correct shipping dock.
6. Shipping
The shipment of right products to the right customer is ensured.

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Figure 9: Operations in Warehouse: Receiving, Inspection, Bulk Storage/Cross Docking, Order
Picking/Sorting, Shipping
2.6.3 RFID tag and reader selection
The various parameters that should be considered for tag and reader selection are
application requirement, frequency, read range, functionality of tags, environmental
conditions, form factor and standard/compliance.
The RFID applications in warehouse include, dock door or portal reading, forklift
reading, conveyor reading, stretch wrap reading and overhead reading. Based on these
applications, there is a need of RFID system that can track tags placed on individual
pallets and cases, at long distances and in large quantities. Low frequency RFID system
has read range of few centimeters. For High Frequency systems, range is up to 1m. For
Ultra High Frequency (UHF) systems range can be obtained more than 1 m and up to
15m or even more. For above mentioned warehouse applications, UHF is the best
suitable frequency due to longer read range and fast and large amount of data transfer.
The environmental conditions and the nature of the product also play an important role in
selecting RFID frequency range. The presence of metals and liquids near RFID systems
can have deleterious effects on RF field like reflection/refraction and absorption. In the

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case of a consumer goods warehouse, UHF range can yield better results by proper
shielding system environment.
Passive tags are the best suitable for warehouse operations. The supplier can fix a
tag with a unique ID on the cases and pallets. This unique ID can be linked to specific
information about individual product ID, product type, product name, date of
manufacturing and batch number, etc.
Form factor plays an important role the range of any RFID system. In the case
leveling tracking, usually a "slap and ship" kind of tag is deployed. In case of pallet level
tagging various forms of tags such as plastic coated tags, label tags etc. can be used.
These kinds of tags are cost effective for warehouse applications.
EPC Global Class 0 tags can be used where the structure of tag information like
the number of object classes is fixed and the tag user does not require programming of
the tag at it site. When the product range changes are very frequent EPC Global Class 1
tags can be deployed. In this case the tag user has the freedom to program the tag
according to its specifications where except the Header partition, all other partitions are
programmable. The user can use its own programming techniques for better security.

28. 28
Section 3: Guidelines for RFID System Design and Deployment
Part 2: Use Case Model and Architecture of Savant
Summary
Software products like any other engineered product should be based on solid analysis
and realistic modeling. A brilliant solution applied to a wrong problem causes as much, if
not more, damage as a bad solution to the problem. Software systems unlike other
engineered products are not physically measurable and hence the relevance of analysis
and modeling becomes more critical in their development. We attempt to define and
describe the middleware of a typical RFID system, called Savants through the use of IBM
Rational Unified Process(RUP)® [13].
3.1 Introduction
3.1.1 RFID technology
Radio Frequency Identification has recently gained much attention owing to the various
mandates by commercial and federal organizations [14], [15]. The concept of using Radio
frequencies to store and retrieve information from products has suddenly made many
hitherto fantasies very practical. Enterprises are keenly interested in the economics of
such a solution. The possibility of tracking every product and being able to store
considerable data into each of them has opened up possibilities of unique identification
and total automation. As can be expected, however, the technology is still not completely
mature in its implementation. There exists a definite lack of benchmarking the
performance of various RFID tags has been seen as a major hurdle to be crossed before
large-scale adoption can be carried out.
RFID solutions typically contain four main components: Tag readers, the Middleware,
the Applications that use the RFID data and the tags themselves. From a systems
engineering perspective, the performance of components on deployment makes a very
interesting study. Clear guidelines, however, on the specifications of each of these

29. 29
components will go a long way in properly understanding the benefits of an RFID
solution.
3.1.2 Savants
The middleware components of an RFID solution are collectively called the Savant. They
are the most important links that collect raw data and convert it into information that can
be understood. Savants are primarily intended to collect, filter and aggregate data that are
derived from the readers. Their primary functionalities also include interfacing with other
enterprise applications that wish to make use of the information they have collected.
The tags read by the tag readers have a unique identification code associated with each of
them. Currently there are two standards associated with naming the products - the ISO
code[16] and the EPC code [4]. These codes contain information regarding the
manufacturer, the current owner, the product type and much more. The savants are
expected to collect the tag data and filter out the replications and smoothen out the data
set and persists the so collected information. We will examine the functionalities of the
savants in more detail in section2.
3.1.3IBM® Rational Unified Process®
IBM Rational Unified Process (formerly known as Rational IBM Rational Unified
Process) is a software engineering paradigm that specifies a UML [17] based
methodology for developing systems. Although the UML is generic and can be applied to
the design and development of any system we primarily apply it to the software
engineering process in this paper.
RUP is IBM Rational Unified Process, or RUP®, is a configurable software development
process platform that delivers proven best practices and a configurable architecture
[13].Our primary focus in this paper is to apply RUP in an effort to understand the
functionalities of a Savant in clear detail and come up with a generic architecture for the
system.

30. 30
3.2 Software Requirements Definition
3.2.1 Goal
To develop and deploy a middleware system that enables effective communication
between the tag-readers and various other external software applications.
3.2.2 Top level requirements definition
1. The system should be able to recognize each reader and gather required
data from it and be able to handle exceptional situations like reader breakdown.
2. The system should be able to perform aggregation activities like counting
the number of items, rate of filling and emptying of aisles/locations of item
storage, Positional counts etc.
3. The System should be able to filter the gathered data so as to help derive
useful information from them.
4. The system should be able to convert gathered data into proper data
formats (PML).
5. The system should be able to persist the data gathered into a predefined
repository. The system should also be able to communicate with the repository
and perform query response activities.
6. The system should be able to communicate with other external
applications like ERP systems (may be other savants themselves) to enable
decision making activities.
7. The system should be able to allow a web user to logon and view various
statistics related to the current status of the data gathered. That is, there should be
a web interface for viewing the information generated by the savant using the data
gathered from the tag reader.
8. The system should be configurable, i.e. it should be able to recognize and
understand various product code specifications

31. 31
3.3.2 Requirements analysis
RUP® suggests that the requirements analysis should be carried out using Use case
diagrams. Use case Diagrams are one of the five Diagrams in Unified Modeling
Language which forms the basis for the Rational Unified Process. They are central to the
modeling of the behavior of the intended system. They aid us in visualizing, specifying
and documenting the intended behavior of the system. They adopt a black-box view of
the system allowing users to specify just the intended use of the system. This paradigm
allows developers to separate the implementation of the system from its interface.
3.3.2.1 Components of a Use case diagram
• Use cases: A use case is a description of a set of sequences of actions,
including variants, that a system performs to yield an observable result of value to
an actor [17]. It is graphically represented as an ellipse. Typically use cases are
represented as verbs.
• Actors: An Actor represents a coherent set of roles that users play when
interacting with these use cases [1]. They typically represent a human, a hardware
device (like tag readers) or even other systems (like other systems). In modeling
terms they represent entity being serviced by the use cases.
• Relationships: Use cases can exhibit aggregation, generalization or just
association relationships. Several stereotypes are used to qualify the relationships
between use cases and actors. Relationships between use cases are also allowed.
• Notes and Constraints: Notes and any specific constraints can also be
stated in an use case diagram
3.3.2.2 Use Case analysis of Savant
We first start with the detection of actors, use cases and then the relationships
respectively.
3.3.2.2.1 Actors
Actors in practical terms are the stakeholders of the system under consideration. Any
change in the system affects the actors alone directly. We expect the following actors for
the savant.

32. 32
1. Web User: Although this actor could be modeled as a part of the Applications,
we choose to model him separately since, the roles and requirements of this actor
are very specific and to an extent different from that of the Applications. This
actor is intended to use the savants directly to gather product information. He is
expected to view the current status of the product inventory. His set of
requirements are as follows:
(a) Login
(b) Logout
(c) View the current status of the RFID installation
2. Tag Readers: The relation between the tag holders and the savant is an inverse
relation in the sense that the services are expected by the savant than by the tag
reader itself. However since the model is for the savant, we try to capture the
requirements as if the tag reader requests for it. The following are the
requirements of the tag reader:
(a) Identify Tag reader
(b) Process Tag reader data
(c) Process Control
3. Applications: These are other software systems which use the data gathered by
the savant to perform other activities. Although, the requirements for the
Applications are custom defined for each deployment, we assume a least common
set of requirements for the current effort. Other requirements could be modeled as
extensions of the existing set of requirements and can easily be accommodated.
The following are identified as the requirements for the Applications
(a) Identify and recognize applications1
(b) Process Application queries 2
(c) Cache queries
(d) Get PML3
1
This could become a critical requirement when the savant information is transacted
between different enterprises automatically, since in such a situation, the savants would
have to recognize the message headers from the enterprise applications
2
Applications could be monitoring the reader information in real time.
3
Applications sometimes prefer data to be in particular formats so that they could

33. 33
3.3.2.2.2 Use Cases
Use cases capture the behavioral description of the system. They formalize graphically
the functional requirements of the system. Although there are no formal set of rules in
detecting the use cases, we try to detect the use cases by as king the following questions
1. What functions does each actor require from the system?
2. What inputs does the system need?
3. What outputs does the system provide for each role?
4. Does the actor need to create, destroy modify or store some kind of
information?
5. Does the actor require the system to identify/validate access?
Basing on the above questions the following use cases were detected.
1. login
Assumptions:
• The user is registered
Main flow:
• The user presents his username and password
• The System recognizes the user and authenticates him
2. logout
Main flow:
• The user logs out
• The system records the changes if any and stops all transactions initiated
by the user
3. view
Main flow:
• The user requests the system to show him specific details.
• The system creates a view with the requested details and presents it to him
Alternate Flow:
• The user is unauthorized to view the requested details
• The systems informs the user about his restrictions and asks him to
understand them. An ideal example would be an XSLT engine which could translate the
PML to any other ML

34. 34
reformulate his request
4. process data
Assumptions:
• The interface of the tag reader is known to the savant
Main flow:
• The savant strips out the headers and converts the data into more a
compact form
5. process control
Assumptions:
• The interface of the tag reader is known to the savant
Main flow:
• The savant instructs the tag reader to perform specific activities
Alternate Flow:
• The savant is not able to communicate with the savant
• The savant generates an alert displaying the status
6. identify reader
Main flow:
• The system recognizes the location indicators in the message headers
• The system recognizes the reader id
Alternate Flow:
• The message headers carry an unregistered savant id or location id
• The system generates an alert displaying the misbehaving reader
particulars
7. process EPC data
Main flow:
• The system recognizes EPC headers
• It extracts the EPC codes from the tag reader data
• It runs preliminary consistency checks to determine if the data obtained is
good
Alternate Flow:
• Corrupt data is obtained

35. 35
• The savant initiates a re-read
8. process ISO data
Main flow:
• The system recognizes ISO headers
• It extracts the ISO codes from the tag reader data
• It runs preliminary consistency checks to determine if the data obtained is
good
Alternate Flow:
• Corrupt data is obtained
• The savant initiates a re-read
9. perform maintenance
Main flow:
• The system performs maintenance activities of the readers. This includes,
checking the communication link between the reader and the savant and similar
activities
10. handle interrupts
Assumptions:
• The interrupt handling procedures are well defined
Main flow:
• The savant recognizes the interrupt
• It initiates the interrupt handling procedure
11. initiate reads
Assumptions:
• Either there has been a ’bad read’ or there is a specific instruction by an
authorized application to initiate the reread process
Main flow:
• The system identifies the reader to be instructed
• It initiates the reread procedure
12. recognize reader id
Assumptions:
• The reader id is registered

36. 36
Main flow:
• looks up the reader id and checks if it matches any existing entry
13. recognize reader location
Assumptions:
• Reader id has been recognized
Main flow:
• Obtains the reader location using the reader id
14. identify application
Assumptions:
• Application interface is known
Main flow:
• Savant associates the application with permissions and restrictions
• Savant associates the application with data formats
15. cache queries
Assumptions:
• Valid queries have been made
Main flow:
• Stores both the query and the result in a local cache for further usage
Alternate Flow:
• The result of a cached query has components which have changed since
last query
• The savant discards the cached information
16. get PML
Assumptions
• The XSD for the PML is known
Main flow:
• The system creates a view specific to the PML document
• It Converts the view into PML
17. process queries
Main flow:
• Checks if there is any cached result

37. 37
• If there is one then the system displays it
• Otherwise, the system initiates a fresh query to the local persistence.
Alternate Flow:
• There is an invalid query
• The system informs the application
18. filter data
Main flow:
• The system checks the data obtained
• It filters out the redundant information from the data and smoothens it out
19. aggregate/create view
Main flow:
• Creates a view from existing data
20. persist
Main flow:
• Stores the filtered data into predefined data structures
Table 6 : Use Case Nomenclature
Number Use Case
Questions
motivating
the discovery
of Use case
Software
Requirements
traced to Use
case
U1 login Q5 SR7
U2 logout Q5,Q4 SR7
U3 view Q1,Q3 SR7
U4 process data Q1,Q2,Q3 SR1,SR8
U5 process control Q1 SR1
U6 identify reader Q2,Q4,Q5 SR1
U7 process EPC
data
Q1,Q2,Q3 SR1,SR8
U8 process ISO
data
Q1,Q2,Q3 SR1,SR8

38. 38
Number Use Case
Questions
motivating
the discovery
of Use case
Software
Requirements
traced to Use
case
U9 perform
maintenance
Q1 SR1
U10 handle
interrupts
Q1 SR1
U11 initiate reads Q1 SR1
U12 recognize
reader id
Q2,Q4,Q5 SR1
U13 recognize
reader location
Q2,Q4,Q5 SR1
U14 identify
application
Q2,Q5,Q4 SR6
U15 cache queries Q1,Q2,Q3 SR5
U16 get PML Q1,Q3 SR4
U17 process queries Q1,Q2,Q3 SR5,SR6
U18 filter data Q1,Q2,Q4 SR3
U19 aggregate/create
view
Q1,Q3 SR2,SR5,SR6
U20 persist Q4 SR5

39. 39
Figure 10: Use case diagram
3.4 Architecture
Architecture of a system depicts the bridge between the actual design and the
requirements model. It tells us meta-relationships between functionalities and structural
components of the requirements model. We depict a generic architecture for the design of
savants which can be implemented through the use of any set of coherent technologies. In
the later section we also present a case study of the Sun Java RFID solution’s savant
architecture.

40. 40
Architectural components are hard to find. Some of them naturally classify into many
architectural modules. Hitting the right granularity of modules becomes a critical decision
during the architecture phase. We as earlier use a question based approach to find
architectural components. Our belief is that with this approach the right granularity is
easier to attain. Some of typical questions we ask ourselves to detect architectural
components are:
1. Are there functional requirements, which operate with the same
interfaces?
2. Are there use cases, which have generalization, aggregation relationships?
3. Are there use cases, which have tightly coupled functionalities?
4. Are there possibilities that use case implementations could be varied over
time?
5. Are there use cases related to specific functionalities like security etc?
In answer to these questions and a few more, we detected that there were the following
architectural components:
1. Reader Interface module: This component handles all the reader specific
activities like reader types, physical reader interfaces etc
2. Event Management module: This component handles all event triggered
activities like parsing the data received, filtering the received data, initiating
rereads in case of bad data and such
3. Information processing module: This module handles the semantics of
the gathered data. It performs aggregation and persistence related activities
4. Application Interface Module: This component allows for application
level customization where the system is configured to interact with particular
application types
5. Messaging layer: This layer forms the bus for message transactions
between different modules
6. Data Access and Filtering: This module handles the different code
formats of the data and filtering of received data
7. Control module: This module handles all physical control activities to be

41. 41
performed by the savant with respect to the tag reader
8. Persistence manager module: this module handles the local and real time
persistence
Figure 11: General Architecture of a Savant
3.5 Case Study: Sun JAVA ™System RFID Software [18]
Sun Microsystems middleware or Savant are geographically distributed servers which are
connected to RFID readers at various locations, collect data from them, and also pass on
the control signals from the ERP systems. Savants in this system:
• Gathers, stores, and processes EPC data from one or more readers
• Smoothes data i.e. filters redundant read values
• Corrects duplicate reader or tag entries
• Stores and also forwards data up or down the architecture
• Monitors for events like low-stock level
• Passes up the data to the ERP systems used by the company either
continuously or on a periodic basis
Information that is typically collected by a Savant includes:
• EPC of the tag read
• EPC of the reader that scanned the tag
• Time stamp of the reading i.e. at what instant of time the tag was read by

42. 42
the reader
• Other information such as temperature or geographical position that the
reader is programmed to collect along with the EPC of the tag
There are three software modules in the Sun’s version of the auto-id architecture:
1. Event Management System (EMS)
2. Real-time in-memory data structure (RIED)
3. Task Management System (TMS)
3.5.1. Event Management System (EMS)
The Event Management system provides event triggered functionality. Its functionalities
include:
• A Java TM technology based system
• Provide a common interface for various types of readers
• Collect data in a standard format
• Allow customized filters to smooth and clean data
• Provide various mechanisms to log data into a database or remote servers
using standard protocols (HTTP, SOAP, Java Message Service and Java Message
Queue)
3.5.2. Real-time in-memory data structure (RIED)
The features of the RIED include:
• Stores event information by Edge Savants
• Provides the same interface as a database, but offers much better
performance
• Applications can access RIED using JDBCTM technology or a native Java
technology interface
• Also supports SQL operations and can maintain snapshots of the database
at different time stamps
3.5.3. Task Management System (TMS)
Task Management system provides an interface to perform administration and
maintenance activities.

43. 43
• It provides an external interface to schedule tasks
• It simplifies the maintenance of distributed Savants because the enterprise
can maintain Savants by merely keeping the tasks on a set of class servers up to
date, and appropriately scheduling tasks on the Savants
• In addition to data gathering and transmission the TMS can be used to
request PML and ONS activity and schedule and administer tasks on other
Savants
Figure 12: Sun Java System RFID architecture for Savant
The below table captures a trace of the Sun java architecture from our Software
requirements:

44. 44
Table 7: Sun Java Architecture
Sun Java
System
RFID solution
component
General
Architecture
component
Use Case
Software
Requirements
Event
Management
Module
U4,U7,U8,U13, SR
Event
Management
System
Data filtering
Module,
Reader
Interface
Module
U12,U18,U11
Real-Time In-
memory
Information
processing
module,
U14,U15,U16,U17, SR
Data Structure
Persistence
manager
U19,U20
Task
Management
System
Control
Module
U5,U9,U10,U11 SR
3.6 Conclusion
Use case analysis and Architectural modeling of Savants enables better understanding of
the system. It provides a basis for further improvements in the design of future versions
of the savant. In addition, it provides us with a basis to perform further refinements into
the savant specifications.

45. 45
Section 4: Summary of Best Industry Practices &
Developments in RFID Systems and their Experimental
Investigation
4.1 Best Industry Practices & Developments in RFID Systems:
Application
/ Area of
Interest
Variables
Affecting Tag
Readability
Description Suggested By
The wear of interconnections between
antenna and chip of a tag affects the
reliability and read distance of the tag.
Effect of tag
wear
Contacts made by silver epoxy or
compression contacts on copper or
aluminum degrade over time and are
affected by high temperatures
Effect of form
factor
There is an almost linear relationship
between the size of tag and its
readability
AVANTE Labs
Effect of
variations in
tags
Effect of tag
orientation
The read range of a dipole tag
increases when the tag becomes
parallel to the field and is least when it
is perpendicular to the field. Tag
flipping reduces the tag readability.
Same is the case with the write range
though it is less in all events as
compared to the read range.
K.V.S. Rao
(Intermec)

46. 46
Application
/ Area of
Interest
Variables
Affecting Tag
Readability
Description Suggested By
Effect of large
number of tags
scanned by a
single reader
The average tag readability in large
scale events is 96.8%
Yusuke
Kawakita, and
et al ( Keio
University
Tokyo, Japan)
Usually tags require 7-8db in power for
reading at a fixed distance of 1m. The
"bad" or weak tags require 25-26 db of
power to get activated. Sorting of such
"bad" tags from a pool of can increase
the tag readability to more than 98%
Effect of
"weak" tags
Sorting of tags on the basis of energy
required to respond is a very time
consuming process and if done in the
RFID printer itself, requires high
degree of calibration when each tag is
tested at variable levels of power. If
done on a post-application level, it
increases the rework by 3-5%.
Dan Dobkin
(Enigmatics)
Effect of tag
velocity on
number of
reads
The number of reads decrease
exponentially with the increase in the
tag's velocity
Effect of tag
velocity on
average
reading time
The average reading time decrease
exponentially with the increase in the
tag's velocity
Katariina
Penttila, and et
al ( Tampere
University of
Technology,
Finland)

47. 47
Application
/ Area of
Interest
Variables
Affecting Tag
Readability
Description Suggested By
Effect of
number of tags
on
identification
time
Tag identification time increases
linearly with the increase in number of
tags in close proximity. Multiple tag
identification is successful only up to
4m/s of tag velocity
Katariina
Penttila, and et
al ( Tampere
University of
Technology,
Finland)
Effect of
high tag
density
Effect of
number of tags
on response
time
The running time in tag response for a
set of 60 tags close to each other but
well inside the optimized field
coverage of the antenna, is more than
6000 milliseconds
Vogt. H.
Antenna size
Increase in antenna size of both the tag
and the reader can increase the read
distance by 25-50%
AVANTE Labs
Effect of
antenna
Relationship
between
antenna
diameter and
read range
100% tag readability of UHF tags is
obtained by properly identifying the
form factor suitable for a specific read
range required for the application. A
tag antenna with diameter of 18 mm
can result in 100% readability only
within 500 mm distance from the
reader
Hosaka, R.
Effect of
reader Power of
reader
Low powered handheld readers can
achieve a reader distance of 1/3rd of
the fixed antenna reader i.e. up to 2-3
feet distance
AVANTE Labs

48. 48
Application
/ Area of
Interest
Variables
Affecting Tag
Readability
Description Suggested By
Forklift mounted RFID readers are the
best in warehouse environments. They
provide the flexibility in inventory
counting procedures.Type of reader
The tags should be placed facing out,
towards the aisle on every asset for this
solution to work properly
John McGinnis
(AVID
Wireless)
Effect of
Liquids
Effect of
proximity to
liquids
Attenuation of signals may reduce the
read distance by few hundred percents
AVANTE Labs
Effect of
Metallic
environments
Proximity to
metals
Metals reduce the read as well as write
range of tag in their vicinity. For a tag
placed on a metal sheet and at a
distance of 1 m from the reader has a
4/5th reduction in read range as that of
a tag not in the proximity of metals
AVANTE Labs
Effect of Rain
Read distance can fall even by 100% in
rainy or high humidity environments
Effect of
climate
Effect of snow
Snow has the same effect as that of
rain, but here the reduction in read
range can be as low as zero
AVANTE Labs

49. 49
Application
/ Area of
Interest
Variables
Affecting Tag
Readability
Description Suggested By
Hardened plastic, foam and plastic
wrap have little effect on tag
readability
Effect of
plastics
To increase the accuracy and precision
of tag readability, use of additional tags
per component, use of higher
frequency ranges, use of additional
receivers, increase in antenna power,
and/or improvement in post processing
data must be practiced
Effect of
wooden
enclosures
Tags covered with wooden blocks from
all sides, have zero readability
Proximity of metals reduce the tag
readability by more than 50% as
compared with non-occluded tagsEffect of
metallic
enclosures
Any line of sight occlusions (involving
metal) between a tag and any of the
receivers results in the occluded
receiver not even detecting the tag
Effect of
packaging
material
Effect of
Ceramics
Tags placed under ceramic moldings
have reduced accuracy and less
readability in tag localization as
compared to non-occluded tags
Tucker Balch,
Adam Feldman
and Wesley
Wilson
Effect of
occlusions
Effect of PVC
pipelines
RFID tags enclosed in a PVC container
have less read range though this
Hussein Al-
Mousawi

50. 50
Application
/ Area of
Interest
Variables
Affecting Tag
Readability
Description Suggested By
decrease in read range is very less.
Effect of
Concrete
Tags up to a distance of 200mm behind
a concrete bar are detectable but
writing range of such tags is just
100mm (though the tag readability also
depends on the water and steel content
of the concrete block)
Effect of air
gap
When tags are enclosed in a plastic
container, a small air gap between the
tag and the container walls increases
the readability
Effect of water
content in
concrete
Water content in concrete blocks,
decreases the tag readability by up to
20%
(Adger
University
College,
Norway)
Use of WiFi
With a WiFi enabled reader, the last
location of the forklift movement with
the identifiable RFID tag can be found
out which can help in relating the tag
movement and its location the
warehouse
Michael Oh
(TCM RFID Pte
Ltd)
Use of
performance
enhancing
technologies
and tools
Use of "SAW-
RFID
Technology"
Surface Acoustic Waves (SAW) work
better and has a read range of around
300 feet. It works better through metals
and tags in the vicinity of metals
John McGinnis
(AVID
Wireless)

51. 51
Application
/ Area of
Interest
Variables
Affecting Tag
Readability
Description Suggested By
The tags have very small data storage
capacity and work only if we do not
need to write anything on the tag and
cost a few dollars.
Able to scan through all shelves to
have an update of stock level with high
tag readability.
High cost of implementation
Michael Oh
(TCM RFID Pte
Ltd)
100% tag readability is possible
Will not achieve 100% performance
above 3 inches off the surface
Use of "Smart
Shelf"
Close proximity of tags may reduce the
tag readability
Ron Marino
(RAM
Engineering &
Consulting,
Inc.)
Use of non-
metallic slider
bed conveyor
Non-metallic conveyor eliminates
electro-magnetic interferences by using
composite polymers that can work at
temperatures ranging from -40°F to
165°F and the conveyor is virtually
transparent to all frequency ranges
(HF, UHF and Microwave). Multiple
readers can be mounted on the within
close proximities. This type of
conveyor helps in reducing scattering
of RF signals due to metals. Upstream
reading and downstream writing or
Carl Forsythe
(Globe
Composite
Solutions, Ltd.)

52. 52
Application
/ Area of
Interest
Variables
Affecting Tag
Readability
Description Suggested By
verification of tags is possible. FID
readers can be mounted, above, below
or on either sides of the conveyor thus
making it possible to achieve any read
angle adjustments
Read range as high as 300mm can be
obtained while using Mu-chip. The tag
is 0.3mm x 0.3mm x 0.06 mm in
dimensions and can be fitted easily on
electronic circuit boards, miniature
electronic parts, etc.
Use of "Mu-
chip"
Very complicated design with high
cost of production
Mitsuo Usami
(Hitachi Ltd.)
Active tags work best in metallic
environments and have high read range
The maximum possible read range
achieved by an active tag is not more
than 9 meters for tags enclosed in
machine tools.
Use of active
tags
The reliable read range is limited to
just above 1.5 meters when used in
chilling stations
Paul Goodrum
and et al
(University of
Kentucky,
Lexington)

53. 53
4.2 Experimental Investigation
4.2.1 Standard tests and test setups
4.2.1.1 Options for varying distance:
Switched attenuator, fully tested and calibrated, to simulate changes in read
distance. An attenuator is a device that attaches to a transmission line (a coaxial cable)
and reduces the power of a signal as it travels from the reader to the reader antenna
through the cable. Attenuators are usually rated in terms of decibels (dB), a logarithmic
measurement of the intensity of emitted energy, and the frequency spectrum they are
designed for. They work by dissipating the RF energy into heat.
4.2.1.2 Tags near metal
To assess the performance of tags near metal, each tag can be placed at varying
distances from a large, flat piece of steel. The tags and metal plate are separated by air.
Then use an attenuator to determine the dB attenuation level at which the tag could no
longer read. A higher attenuation level, expressed in dB, corresponds to a longer reading
distance. At each distance, increase the reader's dB attenuation level until no reads were
observed. This will provide an approximate maximum read distance for each tag.
4.2.1.3 Tags near water
Placing an aquarium near to the reader or in between the reader and the tag
4.2.1.4 Using a spectrum analyzer
A spectrum analyzer can be used to measure ambient RF energy in the room to
ensure that there was no electromagnetic interference that would affect the test results.
4.2.1.5 Antenna pattern
Separating the reader and the tag by a constant distance and rotating one of them
360º with respect to the other - a 3D plot that shows how much RF is radiated in all

54. 54
directions. The same can be repeated inside an anechoic chamber and a comparison can
be provided.
4.2.1.6 Reader placement
Increasing the accuracy of read without placing more readers is of great
importance when considering minimizing the cost of deployment of RFID systems. This
is essentially finding the optimal place for the readers to detect maximum number of tags
Varying the reader antenna placement is usually the easiest thing to try first, but is
one of the trickiest things to do well. The reader antenna must be placed in a position
where powering the tag and receiving data can be optimized for the particular application.
In a multiple antenna system, the radiation pattern of all the antennas must be known as
well as the location of other nearby readers. It is important to keep in mind that the read
range of an RFID system is generally limited by the amount of power that can be
captured by the tag. This requirement serves as a simple guide for determining initial
antenna placement.
Both OATS (Open Air Tests / Free space) measurement and measurements inside
the anechoic chamber can be done to determine the antenna pattern of all the antennas
that we use in the reader and tags. Once the 3D plot of the antenna pattern is plotted, it
will help us largely in the placement of readers [19].
4.2.2 Equipments available for testing
• An anechoic chamber with RF field measurement and analysis instrumentation
• Simulation software’s to simulate the cases
• Spectrum analyzer to measure EM power levels and the frequency domain
measurements of the response of the tags and readers
• Oscilloscope to capture the signal response of the tag and the reader
• Vector Network Analyzer to measure the antenna parameters of the tag and the
readers
• Attenuator – to be purchased

55. 55
• Antenna tuner for better tuning of the tag and the reader antenna
• Signal generator to output certain signals at the desired frequency and power
levels
• Logistics software’s
• Alien and AWID readers/tags
• Computers and software’s for specific readers
4.2.3Proposed test beds:
Some of the proposed test beds are suggested in Figure 13. The idea was imported
from the existing test facility show in Figure 14. For a conveyor belt application, another
test bed is proposed as in Figure 15.
Figure 13: Test setup 1: For pallet testing and moving a loaded cart
Antenna

56. 56
Figure 14 : Test setup[20]
Figure 15: Test setup 2: For conveyor belt applications
4.2.4 Challenges
It is a challenge because the radio waves that underlie RFID technology can go
haywire when placed close to certain items containing liquid or metal. For example,
liquids, like soda in a can, tend to absorb the electromagnetic energy needed to power the
RFID chip. Meanwhile, the metal of the soda can tends to reflect this energy, bouncing it

57. 57
around in unpredictable ways. In either case, the RFID signal sent by a chip to the reader
faces interference, thus dramatically reducing read rates for RFID tags [21].
Could RFID technology be deployed successfully on a factory floor? There are
many issues to address:
• Metal: Both the products and the carts used to transport them around the factory floor
were made primarily of metal, which blocks radio waves. In addition, directly attaching
a tag to metal could create difficulties in reading it. Tags were placed on system
components located on an interior surface of the metal chassis, providing further
reading difficulties.
• Orientation and placement: Tag orientation (with respect to the reader antenna) and
placement on the product had an affect on tag-reading ability.
• Interference: A factory floor is generally filled with radio waves from other sources,
including cellular phones and 802.11 wireless devices. Will these interfere with EPC
network tags?
• Stray or missed reads: The intend is to prove that the readers could sense all tags
that were intended to be read, would not miss any reads, and would not unintentionally
pick up stray reads from units that were passing by.
There are some additional goals, such as determining read accuracy and
throughput in a production environment; enterprise information systems (EIS) integration
capabilities; and gaining hands-on experience. This will be a step toward a larger goal of
determining if an EPC network could be implemented throughout a factory, which is
expected to eliminate manual key entry and inventory counts while providing item-level
tracking and history [22].
The key challenges to using RFID tags are read range and interference from metal
objects. The power and size of the reader antenna, the system frequency, and the size of
the tag will affect the range. Preliminary research has shown that both inductive and
capacitive tags can operate on some products containing metal, such as batteries, but

58. 58
inductive tags need to be specially tuned if they are to be installed on a battery or other
metal-containing object in order to maximize the read range. Capacitive tags have been
shown to work well on metal products such as steel or aluminum cans, though inductive
tags do not. Capacitive tags can also be read through small metal objects, as long as the
metal object is not grounded. Both inductive and capacitive tags work well on fluorescent
light bulbs, even when placed on a part of the bulb containing metal [23].
4.2.4.1 Questions related to readability and usage of RFID with respect to change in
temperature
• How does the tag operate when tags are placed are on the products present inside
a cooler?
• When the tags are stored at high temperature (Higher than the room temperature)
how is the readability affected?
4.2.5 Electromagnetic Issues that the lab can address
There are many physical interactions taking place in an RFID system. The most
important factors are listed below.
4.2.5.1 Absorption and Attenuation
As the electromagnetic field propagates through various materials, the dielectric
loss and conductive losses in the material attenuate the field of the reader as well as the
response signal of the tag. This effect is of particular concern in pallet-level interrogation,
where users desire to read multiple tags embedded inside large heterogeneous pallet
containers. This can be addressed by simulating multiple tags embedded inside a large
pallet using FEMLAB. This will help in better placement of the tags on pallets in a way
that the interference between the tags is minimized.
4.2.5.2 Shielding
Electromagnetic shielding occurs in materials having high electrical conductivity.
In particular, the shielding effect is the result of induced currents by the applied

59. 59
electromagnetic field, which act to cancel the applied field. Understanding this
phenomenon is particularly relevant to situations such as reading multiple items inside a
pallet containing metal cans or liquids, as well as reading items on a shelf through
different shelf materials.
4.2.5.3 Antenna Detuning
The conductive and dielectric environment surrounding an RFID label can result
in a detuning of the label. This reduces the amount of energy being captured by the tag
and also reduces the modulation signal detected by the reader. Although this problem is
most well-known for RFID tags operating at 13.56MHz that have a high Q-factor, this is
also relevant to some degree for 868-930MHz (ultra-high frequency/UHF) RFID labels
as well. In the case of a UHF or microwave backscatter tag, the antenna tuning is
primarily a function of the tag geometries and material properties, but it is also
susceptible to detuning effects if the tag antenna is made highly resonant.
4.2.5.4 Reflections and Interference
The reflected waves from one or more metal surfaces in the environment combine
to produce a non-uniform and non-monotonic variation in the field produced by the
reader due to the phase differences between the multiple paths. This is the same effect
that we experience walking around with a mobile phone inside a building. Depending on
the position of the tag, this interference can either enhance read range or it can destroy it,
leading to "null spots." For a given RFID frequency, if the geometry of the environment
is known, this field variation can be calculated and mapped.
Multiple propagation paths can also be created in situations where the reader field
is partially blocked or absorbed. Examples of this situation might be a loading dock or
warehouse environment where the reader field can be partially blocked by several large
objects or perhaps blocked by containers in the pallets themselves. Once again, in this
case, if the geometry of the environment is known, the interference effects can be
predicted and hopefully avoided.

60. 60
It should also be noted that interference effects (diffraction) can also result from a
single aperture alone. This situation may occur if trying to read distant tags from a high-
frequency reader through a narrow space, such as layers in a pallet or items stacked on a
shelf [24].
4.2.6 RFID security and privacy – can our lab address any of the privacy issues by
doing some preliminary tests
• Cover RFID tags with protective mesh or foil
• How to kill RFID tags?
• Some method of having a encryption thus making the tags not readable with non
legitimate readers
• Using a blocker tag that can shield the other tags being read from non legitimate
readers [25], [26]
4.2.7 Test articles
Test articles are used to evaluate the performance of the tags. Here tests are done
with products that come in plastic containers and metal containers which have the same
shape. The test results will help us in evaluating which tags will be performing better on
plastic containers and what will be the effect of bringing a metal into the same tests. The
test articles are also chosen in various sizes so that the effect of placing the tags at the
right places for large containers can also be determined for increasing the readability.
Cylindrical:
Large – Folgers coffee cans – Plastic/Metal
Medium – Coke cans (Metal) and same size juice bottles (Plastic)
Small - Salt shaker (Plastic)

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4.2.8 Experiments and Results
This is a list of all the experiments that have been conducted in the lab in
marching towards our goals in the research front. In addition to this a novel method for
reading the tags in high metal environment is also under development.
4.2.8.1 No. of tags vs. readability:
Using 20 tags:
Free space
• 20 tags were stuck to a piece of cardboard sheet at random orientations. The tags
are separated from each other i.e., they don’t over lap as shown in Figure 16
• The sheet with the tags is held against the reader at distances 20 inches and 50
inches as shown in Figure 17. The plane of testing is parallel plane and as the
reader antenna is circularly polarized, the orientation of the tags does not matter
• For 20 inches, 18 tags were read successfully and for 50 inches of separation, 14
tags were read successfully
Presence of Metal
• A big sheet of metal was placed right behind the cardboard sheets (Ref: Figure
18) and the same experiment was repeated for a distance of 20 and 50 inches
• With the metal present at the back, for a separation of 20 inches 3 tags were read
successfully and for 50 inches of separation, only 1 tag was read
Note: In this experiment, the tags and the reader antenna are always in the line of sight.

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Figure 16: 20 tags placed on a cardboard sheet in random orientations
Figure 17: Reader antenna and tag sheet separated by a distance of 20 inches in free space

63. 63
Figure 18: Tag sheet placed on a big sheet of metal
Using 50 tags stacked:
• 50 tags are bunched up together randomly and the reader antenna was held at a
distance of 20 inches
• 20 tags were read successfully. The low read is because of the influence of the
tags that are placed one over the other.
• When the separation distance was increased from 20 inches to 50 inches, the
readability reduced further. This is expected. As the read distance increases, the
readability decreases because the power decreases exponentially.
• The results for different tests are tabulated in Table 8
Table 8: Experimental results using 20 and 50 tags
Number of
Tags
Distance between
reader and tag
(inch)
No. of
hits
No. of hits when a sheet of metal
is placed at the back
20 18 320
50 14 1

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Number of
Tags
Distance between
reader and tag
(inch)
No. of
hits
No. of hits when a sheet of metal
is placed at the back
20 20 N/A50
50 13 N/A
4.2.8.2 Tags in books:
4.2.8.2.1 in a book shelf:
Using RFID for maintaining a library and getting quick information on the books
and their availability is also of interest in the RFID field. So some experiments that will
support this theory were done. This experiment is done to get a good idea about tag
placement.
• Alien tags are placed inside the books in a book shelf. Ref: Figure 19
• The tags are placed in a similar fashion that they are located right below the main
cover of the book
• There were in total 38 books present and hence 38 tags
• The reader antenna is placed perpendicular to the books in the shelf

65. 65
Figure 19: Tags placed inside the books in a book shelf
• Number of reads was recorded for varying distance of separation between the tags
and the reader
• The results are tabulated in Table 9
Table 9: Experimental results using tags on books (Tag orientation - perpendicular)
Number of Tags Distance between reader and tag
(inch)
No. of hits
20 22
35 1738
73 8
• From the tabulation it can be seen that the readability decreases with increase in
the distance of separation

66. 66
• Even for small distance of separation, the efficiency of read is low because the
tags are in the presence of metal and as seen from the previous experiments, the
presence of metal at the back of the tags decreases the read rate
• Also the tags are placed in the perpendicular plane with respect to the reader
antenna and as known, the read rate in the perpendicular plane is not high
• Hence the experiment was repeated by putting the tags in the parallel plane with
respect to the reader antenna
• The placement of the tags in a parallel plane and on the books can be seen in
Figure 20
Figure 20: Tags placed on the sides of the books in a book shelf
• When the tags are placed on the sides, they are parallel to the reader so a
enhancement in the readability is anticipated
• The reader is placed at varying distance from the shelf and the number of hits is
determined
• The results are tabulated in Table 10

67. 67
Table 10: Experimental results using tags on books (Tag orientation - parallel)
Number of Tags Distance between reader and tag
(inch)
No. of hits
70 11
40 2233
20 28-30
• As expected the readability has increased when the tags are in parallel in spite of
the metal present behind
4.2.8.2.2 Half filled book shelf:
This experiment was done to look at the change in readability with the change in
tag density. Hence for the same settings the experiment is repeated when the rack in the
book shelf is half empty.
• Number of tags is 18. The tags are placed at the same spot as before
• The reduced number of tags in books placed in the book shelf can be seen in
Figure 21
• The reader antenna is held at a distance of 35 inches from the rack and the number
of hits is determined and the results are tabulated in Table 11

68. 68
Figure 21: Tags placed inside the books in a half filled book shelf
Table 11: Experimental results using tags on books (Tag density – Half as in the precious stage)
Number of Tags Distance between reader and tag
(inch)
No. of hits
18 35 16
4.2.8.2.3 Pile of books:
• The tags are placed inside the front cover of the books and the books are piled up
on the floor as shown in Figure 22
• The reader antenna was placed at a distance of 36 inch from the pile and the
number of hits is determined
• Note: Now the tags are in a parallel plane with respect to the reader antenna and
there is no metal behind the books (While the books were placed in shelves, there
was metal present at the back of the books)

69. 69
• Also as the books are piled in random orientation, the tags are also in random
places
Figure 22: Tags placed inside the books when the books are not in the influence of metal
• The number of hits table is given below in Table 12
Table 12 : Experimental results using tags on books
(Books are stacked on floor. No influence of metal)
Number of
Tags
Distance between reader and tag
(inch)
No. of hits
10 36 10
14 36 14
18 36 16

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4.2.9 Readability with books considering tag density along with presence of metal
After the preliminary set of experiments that was used to determine the readability
of tags when present inside books, a more practical and more procedural experiment was
carried out to determine how the tag density plays a role in the presence of metal when
we are trying to read the tags present in the books.
Note: From the results of previous experiments it was noted that the parallel orientation
of the tag with respect to the reader is giving maximum readability hence, the same is
followed in this set of experiments also. The tag is placed in the side.
• The tags are placed in a similar fashion that they are located parallel to the reader.
Ref : Figure 23 and Figure 24
• The experiment was carried on for two sets of tags
Number of tags = 20
Number of tags = 48
• Three tag densities are used for the experimentation
Low – Sparsely placed
Medium – Closely placed
High – Very tightly placed
• The experiments were carried on for two varying distances (Distance refers to the
distance between the reader and the tag)
Small – 20 inches
Large – 50 inches
• The reader is placed opposite to the tags at the line of sight
• The results are tabulated in Table 13 and Table 14
Table 13: Experimental results using tags on books (Influence of metal)
No. of
Tags
Distance
(inch)
Tag density
Presence of
metal
No. of
Hits
Metal 18
Low No Metal 20
Metal 17
20
Small
Medium No Metal 20

71. 71
No. of
Tags
Distance
(inch)
Tag density
Presence of
metal
No. of
Hits
Metal 18
High No Metal 20
Metal 15
Low No Metal 17
Metal 14
Medium No Metal 11
Metal 15
Large
High No Metal 17
Table 14: Experimental results using tags on books (Influence of metal)
No. of
Tags
Distance
(inch)
Tag density
Presence of
metal
No. of Hits
Metal 35
Low No Metal 38
Metal 31
Medium No Metal 38
Metal 30
Small
High No Metal 38
Metal 29
Low No Metal 32
Metal 21
Medium No Metal 32
Metal 25
48
Large
High No Metal 35
• From the table it can be seen that the presence of metal reduces the readability
and it gets worse with the increase in distance and tag density

72. 72
Figure 23: Tags placed on the sides of the books in free space
Figure 24: Tags placed on the sides of the books in a book shelf

73. 73
4.2.10 Readability in the presence of water
• Plastic bottles are tagged using the Alien 9354 tag. As the reader antenna is
circularly polarized, the orientation of the tag on the plastic bottle is not
significant
This would be significant in using RFID in medicinal applications
like in a drug store where it would be easier to find the stock of
drugs available
• Bottles with the tags placed on them will be placed opposite to the reader as
shown in Figure 25 and Figure 26 and the number of successful reads are
determined for three varying tag densities
• When the tags are placed against water in the bottle, the water will influence the
readability of the RFID system so positioning the tag at the right place on the
bottle is very important
• The effect of having the bottles full of water and half empty with the tags placed
near the brim was determined
• The experiment was carried on for two sets of bottles
Number of bottles = 5
Number of bottles = 10
• Three tag densities are used for the experimentation
Low – Sparsely placed
Medium – Closely placed
High – Very tightly placed
• The experiments were carried on for two varying distances (Distance refers to the
distance between the reader and the tag)
Small – 20 inches
Large – 50 inches
• The results are tabulated in Table 15 and Table 16

74. 74
Table 15: Experimental results using 5 tags on bottles
No. of
Tags
Distance
(inch)
Tag density
Presence of
Water
No. of
Hits
Water 1
Partial 1Low
(Sparsely placed) No Water 5
Water 4
Partial 2Medium
(Closely placed) No Water 5
Water 3
Partial 1
Small
(20 inch)
High
(Tightly placed) No Water 5
Water 0
Partial 0Low
(Sparsely placed) No Water 5
Water 0
Partial 0Medium
(Closely placed) No Water 5
Water 0
Partial 0
5
Large
(50 inch)
High
(Tightly placed) No Water 4

75. 75
Table 16: Experimental results using 10 tags on bottles
No. of
Tags
Distance
(inch)
Tag density
Presence of
Water
No. of
Hits
Water 4
Partial 3Low
(Sparsely placed) No Water 10
Water 6
Partial 2Medium
(Closely placed) No Water 10
Water 2
Partial 2
Small
(20 inch)
High
(Tightly placed) No Water 10
Water 1
Partial 0Low
(Sparsely placed)
No Water 6
Water 0
Partial 0Medium
(Closely placed) No Water 6
Water 0
Partial 0
10
Large
(50 inch)
High
(Tightly placed) No Water 7
• From the table it can be seen that the presence of water affects the readability of
the RFID system and the variation with respect to distance is also obvious

76. 76
Figure 25: Tags placed on the sides of the bottles with high tag density
Figure 26: Tags placed on the sides of the bottles with low tag density

77. 77
Section 5: Statistical Analysis and Design of RFID Systems for
Monitoring Vehicle Ingress/Egress in Warehouse Environments
Summary
Many academic and industry research efforts are currently focused on evaluating
the potentials of RFID technology for industrial applications. Major applications of RFID
technologies are anticipated in warehouse and depot environments. One needs systematic
methodologies for effective design and deployment of RFID systems in these
environments. The authors present a statistically designed experimentation approach
determining the most desirable settings of an RFID system, deployable at vehicle
ingress/egress points of a typical warehouse, depot, or a manufacturing plant. The
approach yields phenomenological insights into the joint effects of multiple RFID system
parameters on the performance of the ingress/egress monitoring system.

78. 78
5.1. Introduction
After September 11, the US government as well as the major industries have
started placing increasing attention on tracking and monitoring of cargo and vehicles
movement [27]. It is becoming imperative for every warehouse, depot, and a
manufacturing plant to monitor vehicle ingress and egress through their premises. As a
result, many commercial warehouse or storage management systems have begun to
include components for vehicle transit monitoring. They are primarily aimed in achieving
the following three basic functions:
(1) Inventory management, (2) safety of the goods, and (3) security of the
warehouse, depot or any manufacturing plant
A typical vehicle transit monitoring system uses checkpoints placed at various
locations within a warehouse. The security personnel need to physically examine and
identify each container or item, most likely by reading the barcode information. This
information is then, transferred to an ERP system to cross-verify the goods being shipped
from or arriving into the warehouse. This procedure has some inherent lacunas. For
example, the system requires at least one dedicated person to carry out the vehicle
ingress/egress monitoring process at each checkpoint, and the system cannot keep a
check on the movement of every vehicle the enters or leaves the premises of a
warehouse. RFID and other such automatic identification technologies offer potential for
surmounting these shortcomings.
A typical RFID system consists of tags (also known as transponders), readers
(sometimes known as transreceivers) and a computer system for storing and managing
the data received from the reader and analyzing it according to the type of software
application that uses it. A transponder is usually a memory device (e.g. EEPROM), fitted
on the object to be identified [3]. It contains information that uniquely identifies an
object. A reader is capable of generating, receiving, demodulating and deciphering RF
signals.

79. 79
Tags are classified, into various types depending on whether they are active or
passive, readable and/or writable, etc., [2]. Based on the protocol of the tags, they can be
differentiated into two main types as EPC and ISO tags. Table 17 represents the
classification of EPC based tags. Among these, Class 0 and Class 1 tags are widely
accepted by the industry due to their cost effectiveness and easy availability. Tags
classified according to the frequency standards in ISO 18000 series [28] are summarized
in Table 2 [5]. Whenever a tag comes into a reader’s RF electromagnetic field, it gets
powered due to the incident electromagnetic field, and sends signals back to the reader
that identifies the tagged object. This identification technology can be used for real time
job tracking, goods and/or asset management, etc., [3].
Table 17: Tag Classification of EPC tags
EPC
Class
Description Functionality Remarks
0 Read Only Passive tags
Data can be written only once
during tag manufacturing and
read many times
1
Write Once and
Read only
Passive tags
Data can be written only once
by tag manufacturer or user and
read many times
2 Read/Write Passive tags
User can read/write data many
times
3 Read/Write
Semi-passive
tags
Can be coupled with on board
sensors for capturing parameters
like temperatures, pressure, etc.
4 Read/Write Active tags
Can be coupled with on board
sensors and act as radio wave
transmitter to communicate with
reader

80. 80
The data carrier frequencies recommended by the Federal laws is as shown in
Table 18
Table 18: Classification of Frequencies
Low
Frequency(LF)
High
Frequency(HF)
Ultra High
Frequency(UHF)
Microwave
125 - 134 KHz 13.56 MHz 902 - 928 MHz 2.4 - 2.48 GHz
As shown in Figure 27, the information stored in a tag is transmitted to a reader at
a carrier frequency. The reader de-modulates the signal and sends the tag information to
the RFID middleware. The middleware consists of an event processor and a link to the
central database. The event processor uses the central database to retrieve tag-specific
data. It then compares the data with that read from the tag. This processed-information is
sent to an enterprise application (EA) such as an ERP system [3]. An EA links the
database and the user so that a user can extract higher-level information with regard to,
vehicle arrival patterns, classification of the vehicle, vehicle authorization, etc.
Figure 27 : RFID Data Flow Diagram[29]
During the last two years, the industry has initiated a few planning studies and
pilot deployments of RFID systems. The industry has envisaged potential of RFID
systems in improving the practices of supply chain management, logistics, machine
health monitoring, warehouse management and customer support. RFID systems are
considered in quite a few scenarios to be a better substitute to bar codes due to their
ability to identify any part, product or vehicle on item level, and they are considered to be

81. 81
more cost effective compared to many global positioning systems. Many companies are
patenting new RFID solutions to an extent that some have started to believe that the bar
codes, which are prevalent in many industrial identification applications, will become
obsolete in a few years. However, RFID systems, at present have some inherent
shortcomings. They include:
1. loss of readability in the presence of metals due to signal scattering,
2. a quadratic reduction in readability of tags with an increase in the distance between
the tag and the reader, and
3. large dependence of readability on the form factor (i.e. shape, size and orientation),
make, standard compliance and reader antennas.
Implementation of RFID system in real world environments therefore requires
careful design and selection of key system parameters such as the tag orientation, reader
make, vehicle speed, etc., in order to optimize pertinent performance variables including
the read rate, robustness to noise, etc. These parameters will henceforth be referred as
Key Process Input Variables (KPIVs), and the key output variables will be referred to as
Key Process Output Variables (KPOVs).
The objective of the work presented in this paper is to derive a statistical approach
towards systematically designing an effective RFID enabled vehicle ingress/egress
monitoring system. The following benefits are achieved using such an RFID based
monitoring:
1. A current system with barcodes requires a person to manually inspect a
vehicle and have the barcode identified by using the barcode reader. An
RFID enabled system, obviates the need for such highly repetitive human
activity, and thus allows fast and easy information gathering. It will
eliminate several non-value added activities and can systematically
reduce the paper work and documentation, and excessive reliance on
routine manual labor.
2. RFID enables easy bulk identification and verification of vehicles and its
contents entering or leaving a warehouse or a manufacturing plant. A

82. 82
RFID system can be coupled with picture identification, thus allowing
faster and robust identification of a vehicle from a remote location [30].
3. The system can be used for monitoring and identification of patterns in
vehicle motion states over time. This information can then be used to
upgrade the current plant and enterprise practices towards improving
overall system performance.
Figure 28 : Schematic of an RFID based vehicle ingress/egress monitoring system
As shown in Figure 28, an RFID based vehicle ingress/egress monitoring system
would require modifications to the existing setup/infrastructure in the form of reader
antennae placed at the entry and exit checkpoints. One may use multiple (at least two)
antennae positioned in tandem to differentiate between ingressing and the egressing
vehicles. These modifications will help in tracking the flow of vehicles in the warehouse
or plant premises. Each vehicle will be equipped with an RFID tag at an appropriate
location (e.g. near the center of windshield). This tag will store information that uniquely
identifies the vehicle. Apart from this, all items/containers may be RFID tagged to allow
identification of the contents of the vehicle. We note that this paper focuses on
determining RFID system elements for vehicle monitoring only. Determination of the

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locations and other KPIVs of RFID tags on the containers requires a separate statistical
and electromagnetic (EM) field analysis, which is beyond the scope of this paper. The
presented approach can be applied to design a layer vehicle monitoring system whereby
the position of vehicles can be tracked by synchronizing antenna signals at various
locations in a warehouse and unauthorized vehicles can be easily tracked and identified.
The remainder part of this paper is organized as follows: A description of our
approach to select the KPIVs from among a large number of system parameters is
presented in Section 2, our experimentation setup and procedures are described in Section
3, and the results are presented in Section 4.

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5.2. Determination of KPIVs
As summarized in Figure 29 and Table 19, an RFID system is influenced by many
factors or Process Input Variables (PIVs). It is important that correct factors be chosen to
yield designs for successful implementation of the vehicle monitoring systems. The
current EM theoretical models are not tractable for capturing the effects of these factors
on the readability in real world environments. Statistical approaches are therefore
imperative for effective design of the RFID systems [31]. Further, different factors will
have significantly diverse influence on readability only a select set of factors have
major influence. Therefore, for facilitating tractable statistical analysis, these PIVs need
to be filtered to extract a more compact set of KPIVs. Some of them are explained below
and detailed further in Appendix A.
Figure 29 : Cause and Effect Diagram

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• The tags used for this application must be durable, cheap and the user must be
able to use its conventions to write relevant data on the tag. So, we propose to use
two types of tags EPC Class 1 [4] and ISO 18000-6 complaint tags [32]
• Orientation of tag is the relative placement of the tag w.r.t. the field of
polarization of the reader’s antenna. This may be parallel and perpendicular or
oblique to the EM field along various planes of references as shown in Figure 30.
The orientation is specified in terms of
angles )180(0,and)90(0,),90,0( °∈°∈°∈ zyx θθθ .
Z
X
Y Reader
Tag
Figure 30 : Tag Orientation (All angles at zero degrees)
• Form Factor refers to the size and shape the tag antenna. It wields a significant
influence on the EM field envelope generated in presence of a reader and the tags,
which in turn is the main determinant of readability.
• Tag Collision is the effect of one or more tags responding to the reader signal at
the same time. This confuses the reader and requires complex algorithms such as
binary tree method, etc., to distinguish between individual tags
θy
θx
θz
Y
X
Z

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• Operating environment holds significant influence on readability. For example,
metal parts of a vehicle can hinder the free flow of information from the tag to the
reader and vice versa, by reflecting the waves in all directions. There are different
tags for different purposes. A tag created exclusively for metallic environments
such as AWID’s ISO 18000-6 tag [33], works well in such environments than a
general-purpose tag. In addition, the presence of other tags and reader antennas
may cause an adverse effect on the EM field. Thus, the presence of more than one
reader antenna may become a PIV in the experimentation.
Table 19: List of PIVs
Sr. No. PIVs
Controllable(C) /
Noise(N) / Fixed(F)
1 Orientation of tag (θy,(θz) C
2 Placement of tag (θx) C
3 Weather N
4 Vehicle type N
5 Frequency range F
6 Speed of vehicle C
7 Reader placement C
8 Reader make C
9 Tag make C
10 Form factor F
11 Electronics installed in the
vehicle
N
12 Tag collision N
13 Metallic environment N
14 Number of reader antennas C
15 Frequency used F
16 Standard compliance C
17 Tag functionality C