1. INTRODUCTION:

RFID is used in the applications such as animal tracking, in hospitals, preventing theft of automobiles, collecting tolls without stopping, managing traffic, gaining entrance to buildings, automating parking, controlling access of vehicles to gated communities, in corporate campuses and airports, dispensing goods, providing ski lift access, tracking library books, buying hamburgers, and the growing opportunity to track a wealth of assets in supply chain management [2].

Radio Frequency Identification is data collection technology that uses electronic tags for storing data. Currently RFID is most commonly used in asset management, inventory system, product tracking, access control, in social media etc [3].

RFID technology can be considered as up gradation on bar codes. RFID technologies focus on tags that emit short-range radio frequency signals. Devices can pick up this signal and that may be networked to databases of varying sophisticated databases that hold student account, attendance or other information that is used by a single entity or by multiple entities [2]. Software integrates information supplied by the tag to the reader with information held in one or more databases.

2. RFID Module

RFID system consists of following mandatory components for successful identification of any object or location.

(1) Tag

(2) Reader or integrator

(3) Software

Fig : 1 RFID Module [2]

2.1 RFID tags

The tag is also known as an "electronic label," "transponder" or "code plate," which is made up of an RFID chip attached to an antenna. Transmitting in the kilohertz, megahertz and gigahertz ranges, tags may be battery-powered or derive their power from the RF waves coming from the reader. A radio frequency identification tag can be attached to the objects to be identified. Two-way radio transmitter-receivers called interrogators or readers send a signal to the tag and read its response [4].

Tag is RFID device incorporating a silicon memory chip usually with on-board rectification bridge and other RF front-end devices, a wound or printed input/output coil, and at lower frequencies a tuning capacitor. The tag contains an antenna connected to a small microchip containing up to two kilobytes of data. Tags may either be read-only or read-write. Read only tags have a factory-assigned serial number that is used as a key into a database. In read-write tags according to the requirement object specific data can be written into the tag by the system user. Field programmable tags may be write-once, read-multiple. Blank tags may be written with an electronic product code by the user. If a tag has no specific identity then it is always susceptible to manipulation [4].

RFID tags contain at least two parts: an integrated circuit for storing and processing information, modulation and demodulation of radio frequency signals collecting power form reader if it is passive tag and some other special functions; and an antenna for receiving and transmitting the signal. The tag information is stored in a non-volatile memory. The RFID tag includes either a chip-wired logic or a programmed or programmable data processor for processing the transmission and sensor data, respectively[4].

RFID tags can be passive, active or battery-assisted passive.

2.1.1 Active tag

An active tag has an on-board battery and periodically transmits its ID signal. It can be read at distances of one hundred feet or more which greatly improves the utility of the device. It may have other sensors that can use electricity for power. The tag cannot function without battery power, which limits the lifetime of the tag. This type of tag is typically more expensive; often costing $25 or more. The tag is physically larger, which may limit applications. The long-term maintenance costs for an active RFID tag can be greater than those of a passive tag if the batteries are replaced. This tag has highest data bandwidth and longest communication range compared to other types of tag [4].

Fig 2 : Active tags [2]

2.1.2 Passive tag

A passive tag has no battery. But to start operation of passive tags, they must be illuminated with a power level roughly three magnitudes stronger than for signal transmission. That makes a difference in interference and in exposure to radiation. As this tag functions without a battery it has a useful life of twenty years or more. The tag is typically much less expensive to manufacture. The tag is much smaller. It may be as small as the size of a grain of rice. These tags have almost unlimited applications in consumer goods and other areas. The tag can be read only at very short distances, typically a few feet at most. This greatly limits the device for certain applications. With this tag it may not be possible to include sensors that can use electricity for power. The tag remains readable for a very long time even after the product to which the tag is attached has been sold and is no longer being tracked [5].

Fig 3 : Passive tags [2]

2.1.3 Battery assisted passive tag

Passive can also be battery-assisted (BAP) with has a small battery on board and is activated in the presence of an RFID reader. When the battery is discharged, BAP RFID tags continue working as common passive RFID tags. BAP tags are usually more expensive than “comparable” passive tags and cheaper than active tags. As for active RFID tags, battery can be a limiting factor for usage in extreme environmental conditions [5].

2.1.4 RFID tags past and present

RFID technology has been around since 1970, but until recently, it has been too expensive to use on a large scale. Originally, RFID tags were used to track large items, like cows, railroad cars and airline luggage that were shipped over long distances, these original tags, called inductively coupled RFID tags which were complex systems of metal coils, antennae and glass. Inductively coupled RFID tags were powered by a magnetic field generated by the RFID reader. Electrical current has an electrical component and a magnetic component and it is electromagnetic. Because of this, you can create a magnetic field with electricity, and you can create electrical current with a magnetic field. The name "inductively coupled" comes from this process -- the magnetic field inducts a current in the wire [9].

Classification of tags

Class 1: This class includes passive, read-only tag with one-time, field programmable non volatile memory.

Class 2: This class includes passive tag with up to 65 KB of read-write memory.

Class 3: This class includes a semi-passive tag, with up to 65 KB read-write memory.

Class 4: This class includes an active tag that uses a built-in battery to power a transmitter that broadcasts a signal to a reader.
Class 5: This class includes an active RFID tag with read-write memory that can communicate with other Class 5 tags or devices.

2.2 RFID reader

RFID reader is very important part of the RFID module. It works as both transmitter and receiver. It can send and receive information from tag. It reads information from tag using an antenna attached with tag using radio waves and passes this data using communication interfaces to host computer. The host computer stores that information for future use for taking necessary actions. When passive tag is used in the system reader pass some signals to tag to make it active so that tag can respond the reader [4].

Fig : 4 RFID reader [2]

Fig : 5 RFID reader [2]

Above figure shows sample readers. Readers also come in different sizes and features.

Readers (interrogators) can be at a fixed point such as

· Entrance/exit

· Point of sale

· Warehouse

Readers can also be mobile, joined, hand-held, or wireless

The RF field generated by a tag reader (the energy transmitter) has three purposes:

1. Induce enough power into the tag coil to energize the tag.

Passive tags have no battery or other power source; they must derive all power for operation from the reader field. 125 kHz and 13.56 MHz tag designs must operate over a vast dynamic range of carrier input, from the very near field (in the range of 200 VPP) to the maximum read distance (in the range of 5 VPP).

2. Provide a synchronized clock source to the tag.

Many RFID tags divide the carrier frequency down to generate an on-board clock for state machines, counters, etc., and to derive the data transmission bit rate for data returned to the reader. Some tags, however, employ onboard oscillators for clock generation.

3. Act as a carrier for return data from the tag.

Backscatter modulation requires the reader to peak-detect the tag's modulation of the reader's own carrier.

2.3 Software

The information which is transmitted to or received by the reader from tag using radio waves should be converted to the logical form understood by the host computer. For this host computer uses different software in different computer languages. This software can be within reader or can be with host computer. For example if the data received from tag is ID of any product then software checks whether product with that particular ID exists in the database or not. If it exists then it takes further required actions. If it doesn’t exist then it prints required messages on user interface [5].

2.4 Sequence of communication in RFID module

• Host Manages Reader(s) and Issues Commands

• Reader and tag communicate via radio frequency signal

• Carrier signal generated by the reader (upon request from the host application)

• Carrier signal sent out through the antennas

• Carrier signal hits tag(s)

• Tag receives and modifies carrier signal

– sends back modulated signal

• Antennas receive the modulated signal and send them to the Reader

• Reader decodes the data

• Results returned to the host application

3. RFID frequencies

RFID uses different frequency bands for different applications. Some examples are given below [3].

· Low Frequency: 125-134.2 KHz and 140-148.5 KHz. This frequency range is generally used for applications like vehicle tracking or animal tracking

· Medium Frequency: 7.400 MHz to 8.800 MHz

· High Frequency: 13.55 MHz to 13.567 MHz The second range is for item tracking or in smartcard.

· Ultra High Frequency: 860 MHz - 960 MHz

· Super High Frequency: 2.45 GHz to 2.454 GHz

4. RFID Application Overview

Radio Frequency Identification (RFID) systems use radio frequency to identify, locate and track people, assets, and animals. There are almost as many RFID applications as there are business types [6].

Automotive

Auto-makers have added security and convenience into an automobile by using RFID technology for anti-theft immobilizers and passive-entry systems [6].

Animal Tracking

Ranchers and livestock producers use RFID technology to meet export regulations and optimize livestock value. Wild animals are tracked in ecological studies, and many pets that are tagged are returned to their owners.

Some animals with serious diseases can be controlled to keep them within some specific range so that we can prevent to spread that disease more. Unique RFID tag can be attached with such animals. Required data like ID, disease name, animal name can be stored in the database. If such animal try to go out of the specific range then software can give some warning message and we can easily track the animal and prevent them to go outside the range [7].

Asset Tracking

Hospitals and pharmacies meet tough product accountability legislation with RFID; libraries limit theft and keep books in circulation more efficiently; and sports and entertainment entrepreneurs find that "smart tickets" are their ticket to a better bottom line and happier customers [7].

Contactless Payments

Blue-chip companies such as American Express, ExxonMobil, and MasterCard use innovative form factors enabled by TI RFID technology to strengthen brand loyalty and boost revenue per customer [7].

Supply Chain

Most of the retailers have discovered that RFID technology can keep inventories at the optimal level, reduce out-of-stock losses, limit shoplifting, and speed customers through check-out lines [2].

Animal tracking

Hospitals

In hospitals RFID can be used to track the location of different staff members and medical instruments [6].

Library

Libraries have used RFID to replace the barcodes on library items. The tag can contain identifying information or may just be a key into a database. An RFID system may replace or supplement bar codes and may offer another method of inventory management and self-service checkout by patrons [6].

Infrastructure management and protection

Company can introduce RFID technology to identify and locate underground infrastructure assets such as gas pipelines, sewer lines, electrical cables, communication cables, etc [7].

Transportation and logistics

Logistics and transportation are major areas of implementation for RFID technology. Yard management, shipping and freight and distribution centers use RFID tracking technology. In the railroad industry, RFID tags mounted on locomotives and rolling stock identify the owner, identification number and type of equipment and its characteristics. This can be used with a database to identify the lading, origin, destination, etc. of the commodities being carried [8].

Security and Control

RFID tags can be attached to ID cards and vehicles. By doing this, secure zones can be created which allow only authorized personal or vehicle to enter or leave [7].

E-Passport

This is the next generation passport. RFID chip is implemented on each passport. This chip holds the digital information and biometric data of passport holder [4]. Also, the recent visiting records are also stored digitally in the chip. The main purpose is to reduce fraud, make immigration control faster and enhance level of security [8].

Patrolling Log Applications

RFID can be used in auditing and controlling security persons themselves. Checkpoints are provided for patrolling security guards. Checkpoints are RFID tags, that security guard have to scan during their patrol. The reader maintains all record. This aids to check the performance of guards as well as to track events [8].

5. RFID systems design issues

Collision

In many existing applications, a single-read RFID tag is sufficient and even necessary: animal tagging and access control are examples. However, in a growing number of new applications, the simultaneous reading of several tags in the same RF field is absolutely critical: library books, airline baggage, garment, and retail applications are a few.

In order to read multiple tags simultaneously, the tag and reader must be designed to detect the condition that more than one tag is active. Otherwise, the tags will all backscatter the carrier at the same time, and the amplitude-modulated waveforms [1].

This is referred to as a collision. No data would be transferred to the reader. The tag/reader interface is similar to a serial bus, even though the “bus” travels through the air. In a wired serial bus application, arbitration is necessary to prevent bus contention. The RFID interface also requires arbitration [1].

So that only one tag transmits data over the bus at one time. A number of different methods are in use and in development today for preventing collisions; most are patented or patent pending, but all are related to making sure that only one tag talks (backscatters) at any one time [1].

Cost

The cost of active tag is about $25 or up and the cost of passive tag is about 7 to 15 U.S. cents. At the moment tags typically represent upwards of 60% of implementation costs, with other spending on systems integration and on readers, agreement on standards for tags, devices and data. This cost should be reduced to improve the utilization of RFID system [1].

Security

In the system of RFID there are many issues related with security and privacy. A common concern is the loss of privacy when companies scan tags to acquire information about customers and then using data mining techniques to create individual profiles. There are many possibilities where RFID tags can be exploited. So some solution should exist to defeat those threats or at least make them harder to execute [2].

Tracking

The tag can be attached with any product. When any customer purchases the tag the store keeper easily track the location of that product as well as the location of that customer. The location information of the customer can be misused by any person [2].

Attacks against RFID

There are many possible attacks which can harm RFID system. Attacker can be any human or any device as well. Some examples are given here,

1. Simple RFID tags do not provide any protection against being read by a wrong reader. Attacker reads the data coming from the tag and can use this data later to make attack against the RFID system. For example if tag is sending total information about any employee of the company then it is possible to create completer profile of an employee by the attacker it collects all information from the tag. That results in a loss of privacy [3].

2. An attacker can interrupt communication between a reader and a tag. At a later time the original tag's response can be reused when attacker receives a query from the reader [3].

3. Most of the tags do not provide any kind of authentication or access control mechanism. So an attacker can read easily read the original tag’s data and can copy that data on the blank tag of same type for later use. The attacker reads the tag's data from an item at a store and creates a new tag that replaces the tag for a similar item with raised price [3].

4. An attacker can jam the frequencies used in any RFID system which will stop the communication between tag and reader. If the tag is simply wrapped in some metal foil then it does not get enough energy to respond the queries from reader and communication stops [3].

5. Reader passes data read from the tag to the host computer using some intermediate interface. If an attacker gets success to inject some virus in the software then it can crash the database where actual data is stored. Virus can also change the data in the database which may not identify the right data [3].

6. Possible solutions to RFID system issues

There are some possible solutions which can improve the RFID system at some extent.

Kill Command

Kill command can be issued to the tag after which it stops communication at all. Once there is a successful communication between the tag and the authenticate reader, kill command can make the system safe [10].

Encryption

Encryption is the way to convert the original data into some other form at one side which can be decrypted at the other end to get the original data. Cryptography provides greater data security by storing encrypted serial numbers on tags. Encryption can’t stop tracking of the tag by attacker. But the only advantage here is that if the data or key of the tag is encrypted then it is not easy for the attacker to read the original data [1].

Tag passwords

Tag can have passwords. A tag could send critical information only if it receives the correct password. One another variation in the password based tag is that tag does not have static password but its password changes each time it is read by the reader. It implements some specific logic or algorithm to get new password. An attacker could not know the password and so when it tries to read the tag with wrong password, the tag simply does not respond at all [10].

7. REFERENCES:

1. http://www.bridge-project.eu/data/File/BridgesecuritypaperDL_9.pdf

2. http://en.wikipedia.org/wiki/Radio-frequency_identification

3. http://www.rfidjournal.com

4. RFID handbook by Claus Finkenzeller and Dorte Muller

5. RFID (Radio Frequency Identification): Principles and Applications by Stephen A. Weis

6. Ron Weinstein, “RFID: A Technical Overview and Its Application to the Enterprise,” IT Pro-fessional, Vol. 7, No. 3, June 2005, pp. 27-33.

7. Roy Want, “An Introduction to RFID Technology,” IEEE CS and IEEE ComSoc, Vol. 5, No. 1, Santa Clara, 2006, PP. 25-33.

8. Badri Nath, Franklin Reynolds, Roy Want, “RFID Technology and Applications,” IEEE CS and IEEE ComSoc, Vol. 5, No. 1, 2006, pp. 22-24.

9. [Landt01] Jerry Landt, "Shrouds of Time": outlines history and present of RFID: http://www.aimglobal.org/technologies/rfid/ resources/shrouds_of_time.pdf

10. http://www.cse.wustl.edu/~jain/cse574-06/ftp/rfid/

Received on 19.02.2014 Accepted on 12.03.2014

Research J. Engineering and Tech. 5(1): Jan.-Mar. 2014 page 33-37