This document discusses the use of radio frequency identification (RFID) devices to manage warehouses. It describes the basic structure of an RFID system including tags, readers, antennas, and application software. It explains how RFID provides advantages over barcodes for warehouse management by allowing multiple items to be scanned simultaneously from a distance in diverse environments. The document outlines how an RFID-based warehouse management system works, highlighting synchronization between readers to avoid interference. It proposes using external sensors and RF absorbing materials to further reduce reader collisions in dense warehouse settings.

1. WAREHOUSE MANAGEMENT WITH RADIO FREQUENCY IDENTIFICATION DEVICE
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WAREHOUSE MANAGEMENT WITH RADIO
FREQUENCY IDENTIFICATION DEVICE
Anirudh Tandon
Student , B.TECH. IV year
Department of Electronics & Communication Engineering ,
SRMCEM , Lucknow-227105
(U.P. Technical University , Lucknow)
ani_bourne87@yahoo.com
Abstract
The Radio frequency identification device (RFID) is the latest ,more secure and fastest technology in
warehouse management. There has a considerable amount of reduction in transaction costs and decrease in
stock shortage with the use of RFID. Most RFID networks include a wide range of automation technologies .
These technologies are RFID tags , RFID readers, RFID smart sensors , RFID controllers .This paper also
stresses on the need for synchronization between the readers in denser environments to avoid serious reader
collisions.
Index Terms: RFID , Automation , Warehouse , Synchronization .
1. Introduction
2.1. The basic structure of RFID system
Radio Frequency Identification (RFID) is a A whole set of RFID system is composed of
technology to realize no contact information four parts, which are, Reader, Tag (also
transmission by the application to radio known as responder), Antenna and
frequency signal and space coupling Application Software System. The basic
(alternating magnetic field or electromagnetic structure of RFID is shown as
field) and identify with the information C h a r t 1.Its working principle is as such:
transmitted. As a promising technology, RFID Reader transmits radio wave energy of a
products have been playing important roles certain frequency to the receiver so as to the
inn materials circulation and supplychain receiver circuit could sent forth the data inside
management, anti-counterfeit and safety and the Reader then receives and read the
control, traffic management and control and data in sequence and finally sent to the
production management and control and have application program for corresponding
improved the efficiency of management and processing.
commercial value of industries such as (1) Tag
service,manufacture, commercial distribution, Tag is the real carrier of RFID system.
transportation, military, postal service and Generally speaking, a tag is made up of a tag
tobacco. It is predicted that RFID antenna and a special tag chip. Each tag has
technology will be an important technology one single electronic code to be attached on
that changes people’s life in the 21st century. the target object of a substance. Tag functions
as barcode symbol of the bar code technology
and is used for the memory of information
2. Working Principle of RFID needs identifying and transmitting.
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2. WAREHOUSE MANAGEMENT WITH RADIO FREQUENCY IDENTIFICATION DEVICE
According to the difference between the and writing to the tag. It could be database or
power supply modes of the tag, it could be management information system in an
divided into active tag and passive tag, from enterprise. Users could buy highly
the functions, it could be divided into RO, specialized inventory management database
RW, tag with microprocessor and tag with which is designed for certain industries
transducer, from the type of modulation, tag
could also be divided into active tag and 2.2. The work flow of RFID system
passive tag . The basic work flow of RFID system is,
(2) Reader after Reader transmitting radio frequency
Reader is the device used to read or signal with certain frequencies through
write the tag information. It could read, transmitting antenna, the induced current
write, indicate and process solely or work will be produced while entering along
with other computers or systems to with the target object of the tag into
complete the operation to the tag . the working area of transmitting antenna
and then, relying on the energy obtained
by the induced current, the tag transmits
the product information memorized in the
chip or transmit signal of a certain
frequency actively, after the
demodulation and decoding of carrier
wave signal sent from the tag to the
receiving antenna, the Reader sends the
information to data management system for
relevant treatment, data management system
judges the validity of the tag by logical
operation and processes and control
correspondingly according to the different
settings and then send out command signal
to control the operation of actuator.
3. The Application of RFID
A typical Reader is made up of control Technology in
module, radio frequency module, and Warehouse Management
interface module and Reader antenna.
Besides, there are additional interfaces 3.1. The advantages of RFID technology
(RS232, RS485 and interfaces of Ethernet, compare with the traditional Bar Code
etc.) for many Readers to transmit the Compare with bar code, RFID electronic
data received to application system or label has several advantages as following:
receive orders from them. First, Quick Scan: Bar code scans one
(3) Antenna bar-code each time, RFID identifier can scan
Antenna is the device used to provide radio several RFID labels at the same time.
frequency signal transmission space for tag Second, Volume Miniaturization and
and Reader. It could be installed inside the Figure Diversification: The accuracy of
Reader or connected with the antenna RFID access does not require fixed paper
interface of it through coaxial cable. size and quality of printing, it is not limited
(4) Data management system by measures and figures. Moreover, RFID
Data management system mainly label could head for volume
memories and manages the data and miniaturization and figure diversification to
information as well as controlling the reading
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3. WAREHOUSE MANAGEMENT WITH RADIO FREQUENCY IDENTIFICATION DEVICE
apply to different production. inspection, warehousing, cargo delivery,
Third, Anti-pollution and Durability: allocation, cargo shift, inventory check
Traditional bar code is made from paper and other operation process to ensure the
accuracy and speed of the input data. Thus the
which is easily polluted. However, RFID enterprise could master the real storage data
has a strong resistance of water, oil and at the first time, which could help them
chemistry medicine, etc. Besides, as the reasonably keep and control the storage.
bar code is always attached on the plastic The mainly management objects which apply
bag or outer packing of cardboard boxes, it to RFID technique in enterprise warehouse are:
is easily damaged, RFID label stores the data 1) Warehouse Goods: It is the direct
in the chip, so it is anti-pollution. object in warehouse management. It is
classified into three forms: stock, box body and
Fourth, Replication Using of RFID Label: bulk pack. At present RFID does not apply to
The bar code today can hardly changes the single small goods management, so it is used in
information after printing, RFID label could whole box or whole stock (including single
add, amend and delete the data in the label large goods) management.
repetitively, which convenient the renew 2) Inventory Location: It refers to the district
of the information. used to place warehouse goods and doesn’t
overlapping in room. Usually, one inventory
Fifth, Penetrability and Exposed Reading: location could place several warehouse goods
RFID could penetrates communication or a large one warehouse good occupies several
despite paper, wood, plastic and other non locations.
metal or non transparent materials. Bar 3) Warehouse Management Device: It refers
code scanner could read the data only in a to the devices used in warehouse
near range and without other materials block. management, e.g. fork lift truck and hand
Sixth, Large Data Memory: The truck, etc. These devices should be proper
dispatched in time and location so as to
volume of one- dimensional bar code is improve the utilization ratio in large and busy
50Bytes while two-dimensional bar code has warehouse.
2-3000 Bytes. RFID has several MegaBytes (2) Management Task
volume maximum. With the development 1) Each inventory location has an
of memory carriers, data volume is on the electronic label which called inventory label.
trend of expansion. In future, the introduction During the operation of warehouse
could carry more and more data, thus the label management, determine the operation location
need to expand its volume. according the number of the label.
Seventh, Security: RFID carries electronic 2) The warehousing goods, for
information whose data guided by the passing management, each of them has an electronic
number and thus the content is not easy to label which called goods label. The goods has
imitate or revised. goods label should be whole large goods
which easy to labeling. During the
3.2. Object and Task of RFID warehouse operation, reading the number of
Technique in Warehouse Management the label to check the operation goods. On
(1) Management Object the purpose to save the operation cost, goods
Traditional warehouse management depends label should designed to be the label which
on non automatic system which is based could be makes a full use and could be pick
on recorded paper document to pursuing off for replication use at warehousing location.
the import and export goods, completely 3) Set up wireless LAN which covered
performed by personnel. So the depot the whole shipping department to translate
management rate is very low and the the operation data immediately. Install the
scale of the warehouse is very small. fixed wireless date termination on the fork lift
Warehouse management system based on RFID truck, and hand held wireless date termination
refers to the system which imported the for each manual operation staff. The
RFID technique. It exquisites the data wireless date termination can receive the
automatically on the chains of receiving
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4. WAREHOUSE MANAGEMENT WITH RADIO FREQUENCY IDENTIFICATION DEVICE
operation order, confirm the operation location RFIDTechnology
and feedback the operation situation. 4) Use The Warehouse Management System
AGV (Automatic Guided Vehicle) as the is mainly composed by three main parts:
platform to install the RFID scanner, (1)Basic Management Subsystem: it takes
controlling device and radio communication charge of centralized management and
equipment. The AGV truck which installed maintenance of database of WMS, the
the scanner could check the warehouse establishment of stock plan and ex-warehouse
automatically in the appointed time every plan and carry-out of orders, together with
day and conduct the result to the system make out various management report forms.
management center. (2)Warehouse Location Management
Subsystem: it issues labels of entering
3.3. Framework of RFID in WMS into the warehouse and undertakes real-
Warehouse Management System adopts the timed stock management together with
framework with three layers, described as giving orders of warehouse management
follows : operation through wireless communication
The first layer is Capture, that is, capture data
network.
mainly throughRFID equipment and other
(3)Operation Management Implementation
automatic discrimination equipment,
including labels of storage location, labels Subsystem: it completes specific operations
of consignment, wireless data terminal, AVG of entering warehouse, ex-warehouse, shifting
vehicle, etc. warehouse, distribution and check of
The second layer is Movement, that is, warehouse, etc. The implementation of every
transfer the captured data to the central data tache can be queried according to assignment.
warehouse through wireless communication The disposition of RFID equipment in
technology, including wireless access warehouse management refers to Chart-3.
equipment and some relevant network
equipment. Chart-3 Disposition of RFID Equipment in
The third layer is Management, that is, Warehouse Management
analyze and manage the captured data,
including the server of some equipment, such
as database, network, etc. together with some
systematic software of warehouse management.
1ˉthe computer server of stock management
database 2
ˉthe wireless office computer 3ˉthe printer of
labels
of warehouse entry 4ˉthe laser printer 5ˉthe
wireless
antenna 6ˉthe wireless equipment terminal of
forklift 7
3.4. Composition of WMS Based on the ˉthe wireless long range code scanner 8ˉthe
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5. WAREHOUSE MANAGEMENT WITH RADIO FREQUENCY IDENTIFICATION DEVICE
handheld wireless terminal “Listening” at the same time, will start
“Talking” at the same time. If a reader is
4. Synchronization Of Readers turned on at a different time, or if a reader
loses synchronization that reader will
4.1 Tuning start again in synchronism with the rest of
EPC Radio-frequency Identification the readers, after the last reader has finished its
Protocols Class 1 Generation 2 UHF “Talk” session . . Two readers assigned to be
RFID Protocol for Communication at 860 operating in a same channel will be as far apart
MHz – 960 MHz”, in short EPC C1G2, is as possible. Also, the neighbouring antennas
the standard protocol developed by EPC will be using channels as far apart as
global for RFID devices for use within the possible. The spectrum is split into 10
supply chain. With the implementation of ETSI channels, all 5 of the odd-numbered channels
302 208 and EPC C1G2, it was discovered are reserved for tag backscattering while all 5
that when a reader is operating at a certain of the even-numbered channels are assigned
sub-band or channel, this reader will for reader interrogation. . The antenna on the
effectively prevent other readers from using furthest left is using channel 2 for
that channel within an unacceptable large area. interrogation. The next antenna on its
Under the concept of reader synchronization, immediate right is using channel 8, which
all the RFID readers in a certain area, for is 6 channels away. Channel 10, though is
example all the readers in a warehouse, are the furthest channel away, is not chosen.
networked together through a central control This is because the arrangement of [2, 8,
unit. 4, 10, 6] gives best channel separation
between every channel.
4.2 Using external sensors
Sensors can be used to turn RFID reader on
only when tags are approaching to further
reduce reader interference in that area. This
will free up the channels allocated for those
antennas, and also to avoid unnecessary
interference to other surroundings reader
antennas.
Fig 1. “listening” and “talking” mode
Fig3.using external sensors both the antennas
at dock door 3 are switched off when absence
of truck 3 is detected.
Fig2. Channeling of the allocated frequency
spectrum 4.3 Using RF absorbing materials
Another effective, but more expensive,
The connection method can be the common way to reduce readers interference and
Ethernet connection, or equivalent. All the collision, is to utilize RF opaque or RF
readers are “Listen Before Talk” compatible. absorbing materials to contain the
They are configured to start to “Listen” at the interrogating signal within the designated
same time, and then at the end of the listen zone of interrogation. Although there collision,
period, they can all synchronously start to is to utilize RF opaque or RF absorbing
“Talk”. All the readers, which start materials to contain the interrogating signal
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6. WAREHOUSE MANAGEMENT WITH RADIO FREQUENCY IDENTIFICATION DEVICE
within the designated zone of interrogation. 6. Acknowledgement
In the end I would like to acknowledge Hui
Tan(Department of business management,
Nanjing Institute of Industry Technology,
Nanjing, Jiangsu ,China).
Fig3. use of RF absorbing mateials.
7.References
Although there will signal leakage through the
door openings, it would not have caused [1].Hui Tan,”The Application of
much interference. This is due to the fact RFID Technology in the
that the signal strengths at the sides of the Warehouse Management
antenna are relatively weak as compared to the Sys t e m” ,IEEE International
front of the antenna. Accordingly the gain at Symposium on Electronic
the side of a typical RFID antenna is Commerce and Sec urit y. pp.1-
approximately 20 dB less than the gain at the 3,August2008.
front of the antenna.
[2].Kin Seong Leong,Mun Leng
5.Conclusion Ng ,Alfio R. Grasso , Peter
H. Cole, ”S ync roni za ti on of RFI D
RFID has gradually become an indispensable Reader Environments” ,IEEE
technical tool and measure to improve International Symposium on
management level of logistics and supply Applications and the Internet
chain, decrease cost, realize the Workshops.pp3-4 ,2006.
informationization of enterprise management
and increase competitive strength. Many [3].Glover,B.,Bhatt,H.,”An
typical cases abroad suggest that, the Introduction to RFID” ,Chap. 1.
enterprises which have presently applied RFID ESSENTIALS .pp12-
RFID technology into the warehouse 14,O’REILLY,2006.
management information system have
decreased the error ratio of their producing [4].Badri Nath ,Franklin
goods. This paper has identified Re ynolds and RoyWant ,”RFID
synchronization of RFID readers as a Technology and Applications”
mechanism to assist in RFID readers ,IEEE Pervasive Computing,
deployment in dense reader environments. vol.5,no.1,pp.22-24,Jan-March
Several fine-tuning methods are also 2006.
presented in optimising the performance of a
synchronised RFID system. As compared to
conventional unsynchronised RFID systems,
a synchronised RFID system can offer more
coverage, less reader collision or
interference, while strictly following the
European regulations and the EPC C1G2
recommendation. However, these benefits
require the use of more complex hardware
and hence can marginally increase
deployment costs.
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