1. Introduction

The 1800s marked the beginning of the fundamental understanding of electromagnetic energy. Michael Faraday, a noted English experimentalist, proposed in 1846 that both light and radio waves are part of electromagnetic energy. In 1864, James Clerk Maxwell, a Scottish physicist, published his theory on electromagnetic fields and concluded that electric and magnetic energy travel in transverse waves that propagate at a speed equal to that of light. Soon after in 1887, Heinrich Rudolf Hertz, German physicist, confirmed Maxwell's electromagnetic theory and produced and studied electromagnetic waves (radio waves), which he showed are long transverse waves that travel at the speed of light and can be reflected, refracted, and polarized like light. Hertz is credited as the first to transmit and receive radio waves, and his demonstrations were followed quickly by Aleksandr Popov in Russia.

20th Century
In 1906, Ernst F. W. Alexanderson demonstrated the first continuous wave (CW) radio generation and transmission of radio signals. This achievement signals the beginning of modern radio communication, where all aspects of radio waves are controlled.
In the early 20th century, approximately 1922, was considered the birth of radar. The work in radar during World War II was as significant a technical development as the Manhattan Project at Los Alamos Scientific Laboratory, and was critical to the success of the Allies. Radar sends out radio waves for detecting and locating an object by the reflection of the radio waves. This reflection can determine the position and speed of an object. Since RFID is the combination of radio broadcast technology and radar.

The 1960's through the 1980s: RFID Becomes Reality
The 1970's were characterized primarily by developmental work. Intended applications were for animal tracking, vehicle tracking, and factory automation. Examples of animal tagging efforts were the microwave systems at Los Alamos and the inductive systems in Europe. Interest in animal tagging was high in Europe. Alfa Laval, Nedap, and others were developing RFID systems.
The 1980s became the decade for full implementation of RFID technology, though interests developed somewhat differently in various parts of the world. The greatest interests in the United States were for transportation, personnel access, and to a lesser extent, for animals. In Europe, the greatest interests were for short-range systems for animals, industrial and business applications, though toll roads in Italy, France, Spain, Portugal, and Norway were equipped with RFID.
Research and development didn't slow down during the 1990s since new technological developments would expand the functionality of RFID. For the first time, useful microwave Schottky diodes were fabricated on a regular CMOS integrated circuit. This development permitted the construction of microwave RFID tags that contained only a single integrated circuit, a capability previously limited to inductively-coupled RFID transponders. Companies active in this pursuit were IBM (the technology later acquired by Intermec) Micron, and Single Chip Systems (SCS).

The 1990's
The 1990's were a significant decade for RFID since it saw the wide scale deployment of electronic toll collection in the United States. Important deployments included several innovations in electronic tolling. The world's first open highway electronic tolling system opened in Oklahoma in 1991, where vehicles could pass toll collection points at highway speeds, unimpeded by a toll plaza or barriers and with video cameras for enforcement.
Interest was also keen for RFID applications in Europe during the 1990s. Both Microwave and inductive technologies were finding use for toll collection, access control and a wide variety of other applications in commerce.

Back to the future: The 21st Century
Exciting times await those of us committed to the pursuit of advancements in RFID. Its impact is lauded regularly in mainstream media, with the use of RFID slated to become even more ubiquitous. The growing interest in telematics and mobile commerce will bring RFID even closer to the consumer. Recently, the Federal Communications Commission (FCC) allocated spectrum in the 5.9 GHz band for a vast expansion of intelligent transportation systems with many new applications and services proposed. But, the equipment required to accommodate these new applications and services will necessitate more RFID advancements.



The new generation of casino chips is giving insights into the way banks and shops could keep track of real money if it was tagged. Casino operators routinely monitor gamblers with security cameras, just as retailers monitor stores for shoplifters. Aside from improving security, RFID-tagged casino chips could also be used to track how people play. Casino operators can keep tabs on the fortunes of every gambler on their premises, recording the stakes placed by each player along with their winnings and losses. The casinos want to check that big winners are not cheating the house, and to identify lucrative "high rollers" and encourage them to keep playing by treating them to free meals, show tickets, or hotel rooms. But this monitoring has to be done by human observers and is haphazard and unreliable. Chip tracking could dramatically improve the process.


The Decades of RFID

Decade Event
1940 – 1950 Radar refined and used, major World War II development
effort.
RFID invented in 1948.
1950 – 1960 Early explorations of RFID technology, laboratory
experiments.
1960 – 1970 Development of the theory of RFID.
Start of applications field trials.
1970 – 1980 Explosion of RFID development.
Tests of RFID accelerate.
Very early adopter implementations of RFID.
1980 – 1990 Commercial applications of RFID enter mainstream.
1990 – 2000 Emergence of standards.
RFID widely deployed.
RFID becomes a part of everyday life.



RFID systems are essentially short-range, low frequency, low-bit rate wireless networks. Since their origins in the late 1940s, they have been developed specifically to exchange small amounts of data over relatively short distances using tags and readers based on proprietary air interface protocols. RFID applications are starting to “piggy back” onto today’s established WPANs and WLANs using active tags that communicate with these networks’ air interface protocols. In this sense, active RFID tags are a subset of more common communication devices like cell-phones, PDAs, and WiFi-enabled laptops, only with fewer input/output features (like keypads, screens, etc.) and transmitting less data. Similarly, RFID networks are a subset of today’s broad menu of wireless networks, as shown in fig 1.1. while ZigBee-enabled RFID will use wireless sensor networks to track mobile assets. Similarly, WiFi-enabled RFID allows organizations to leverage existing WLAN investments or choose to invest in a wireless infrastructure that will have multiple purposes, rather than building separate networks. NFC is a more recent wireless technology used in combination with RFID. NFC is essentially a WPAN technology with an even shorter range – about 20 centimeters – and lower data rates than Bluetooth. The technology supports a “touch paradigm,” where devices (including smart cards or mobile phones with embedded tags and readers) are brought very close together, or actually touch, to intuitively create a connection between tag and reader. NFC-based RFID may be used to automatically configure a higher-bandwidth connection like Bluetooth or WiFi between two devices.

Another typical application involves tapping a concert poster with a cell phone to automatically connect to a Web site over the mobile phone network to buy a concert ticket or download a song. NFC technology is compatible with the established smart-card infrastructure for contactless smart cards (wave or tap instead of swipe), which enables NFC phones to function as the smart card for mobile payment applications. Mobile payment using cell phones is already very popular in Japan. NFC technology is aimed primarily at consumer applications and analysts predict that 50% of mobile phones will be NFC-enabled by 2009. Mobile operators in Japan like DoCoMo and Vodafone have installed the necessary software on most of their new phones, increasing the popularity of these applications in Asia over the last couple of years.

Figure 1.1: Wireless technologies

Radio frequency identification or RFID, is rapidly becoming widespread enabling remote objects to be identified automatically. The person contributing more than any other single individual to this application of radio technology is Charles Walton of Los Gatos. The first successful application was for an RF coupled proximity key entry through locked doors. Mr. Walton formed a company with several associates, and sold the technology to Schlage Lock of San Francisco. Millions of radio frequency cards using this system have been sold and put into use. Mr. Walton invented several distinctly different forms of radio frequency ID, licensing the technology to several companies,and chose the frequency of 13.56 MHz for the RFID application,which has become a standard frequency. Charles also built systems to identify vehicles, eliminating the need to stop to pay a toll.
Walton will talk about his experience with RFID technology, and his experiences with starting companies. Charles began his involvement in RFID back in 1970. The RFID system they developed consisted of a transmitter that sends a signal of a few milliwatts that sweeps over a relatively wide frequency range, and a passive receiver that responds at one particular frequency.
A typical RFID system consists of a RFID tag (antenna or coil attached) with its unique electronic product code, a transceiver (reader with decoder), and the computer network (if any) that is used to connect the readers. RFID system mostly relies on RFID tags, reader and computer network for the identification of asset. All the basic components of RFID will be explained below priority wise.



2. RFID Tags
RFID tag or transponder is the basic building block of RFID system. Each tag consists of an antenna and a small silicon chip that contains a radio receiver, a radio modulator for sending a response back to the reader, control logic, some amount of memory, and a power system. These form the inlay which is encapsulated in glass or plastic coating according to the application to form the finished tag. tags may contain as large as 1024 bits depending on the requirement. The read range of tags largely depends upon the antenna circuit, size and the transmitting power of the reader.
fewTag is attached to or embedded in an object to be identified with the particular information to be retrieved, such as a product, case, or pallet, and can be scanned by mobile or stationary readers using radio waves


Fig.2.1: RFID tag[2]

.

2.1. Active tags[3]
Active tags are usually read/write devices. These are capable of initiating communication unlike passive tags which mean they are always on. They derive power from an on-board battery capable of supplying the circuitry with power as well as enabling a longer range of broadcast to the corresponding reader. Therefore they somewhat overcome the need of larger reader power for longer distances transmission. However their lifetime is limited due lower battery life and they are also more expensive than passive tags. Longer ranges, better immunity to noise and higher transmission rates are among the obvious benefits. They are employed for asset management and real time location system (RTLS).

2.2. Passive tags [3]
Passive tags are the simplest, smallest and cheapest version of an RFID tag as they do not contain a built-in power source and consequently cannot initiate communication with a reader. They are tiny resource-limited computers that are inductively powered by the energy of the request signal sent from RFID readers. The reader first interrogate the tag with a query through electromagnetic waves which when coupled with the antenna of tag energizes it. These tags are inexpensive, costing less than a quarter . They have limited amount of memory capacity. They also have a very long life span unless they are damaged or torn therefore are widely used in many different retail items. Passive tags can operate at low, high, ultrahigh, or microwave frequency but are ore exposed to electromagnetic noise.
A small part of the emitted field penetrates the antenna coil of the transponder,which is some distance away from the coil of the reader. A voltage Ui is generated in the transponder’s antenna coil by inductance. This voltage is rectified and serves as the power supply for the data-carrying device (microchip). A capacitor Cr is connected in parallel with the reader’s antenna coil, the capacitance of this capacitor being selected such that it works with the coil inductance of the antenna coil to form a parallel resonantcircuit with a resonant frequency that corresponds with the transmission frequency of the reader.





Figure 2.2 :Power supply to an inductively coupled transponder from the energy of the magnetic alternating field generated by the reader[3]

The antenna coil of the transponder and the capacitor C1 form a resonant circuit tuned to the transmission frequency of the reader. The efficiency of power transfer between the antenna coil of the reader and the transponder is proportional to the operating frequency f , the number of windings n, the area A enclosed by the transponder coil, the angle of the two coils relative to each other and the distance between the two coils.

2.3. Carrier
This part consists of a Radio frequency (RF) sine wave generated by the reader to transmit energy to the tag and retrieve data from the tag. This frequency is the leading factor that determines RFID range, resistance to interference and other performance attributes. Most of the RFID systems use the unlicensed spectrum, which is a specific part of the spectrum set aside for use without a radio license. Popular bands are the low-frequency (LF) band at 125–134.2 KHz, the high-frequency band at 13.56MHz, the ultrahigh-frequency (UHF) band at 859 to 960MHz (e.g. EPC global Gen 2), and the industrial, scientific, and medical (ISM) band at 2.4GHz used with expensive battery powered tags

3. Components of a reader
Readers in all systems can be reduced to two fundamental functional blocks: the control system and the HF interface, consisting of a transmitter and receiver (Figure 3.1) In order that it can be integrated into a software application, this reader has an RS232 interface to perform the data exchange between the reader (slave) and the external application software (master).



Figure 3.1: Master–slave principle between application software (application), reader and transponder[4]

First, a signal of the required operating frequency, i.e. 135 kHz or 13.56 MHz, is generated in the transmitter arm by a stable (frequency) quartz oscillator. To avoid worsening the noise ratio in relation to the extremely weak received signal from the transponder, the oscillator is subject to high demands regarding phase stability and sideband noise. The oscillator signal is fed into a modulation module controlled by the baseband signal of the signal coding system. This baseband signal is a keyed direct voltage signal (TTL level), in which the binary data is represented using a serial code (Manchester, Miller, NRZ). Depending upon the modulator type, ASK or PSK modulation is performed on the oscillator signal.



Figure 3.2: Block diagram of a reader consisting of control system and HF interface[5]

3.1 HF Interface
The reader’s HF interface performs the following functions:
•Generation of high frequency transmission power to activate the transponder and supply it with power;
•Modulation of the transmission signal to send data to the transponder;
•Reception and demodulation of HF signals transmitted by a transponder
Reader antennas in inductively coupled RFID systems generate magnetic flux , which is used for the power supply of the transponder and for sending messages between the reader and the transponder.
This gives rise to three fundamental design requirements for a reader antenna:
• Maximum current i1 in the antenna coil, for maximum magnetic flux ;
• Power matching so that the maximum available energy can be used for the generation of the magnetic flux;
• Sufficient bandwidth for the undistorted transmission of a carrier signal modulated with data.

3.2 Control unit
The reader’s control unit (Figure 3.2) performs the following functions:
• Communication with the application software and the execution of commands from the application software;
• Control of the communication with a transponder (master–slave principle),
• Signal coding and decoding (Figure 3.3).
Data exchange between application software and the reader’s control unit is performed by an RS232 or RS485 interface




Figure 3.3: Signal coding and decoding is also performed by the control unit in the reader[6]

RFID TODAY & TOMORROW
Libraries: Some libraries have implemented RFID systems to facilitate book checkout and inventory control and to reduce repetitive stress injuries in librarians
Smart appliances: By exploiting RFID tags in garments and packages of food, home appliances could operate in much more sophisticated ways. Washing machines might automatically choose an appropriate wash cycle

Health: Personal medical RFID card with prescription, RFID tagging of pharmaceuticals

Shopping: In retail shops, consumers could check out by rolling shopping carts past point-of-sale terminals


ADVANTAGES OF RFID[7]

• Non-line-of-sight Scanning
• Simultaneous Automatic Reading
• Labour Reduction
• Enhanced Visibility and Forecasting
• Asset Tracking
• Item Level Tracking
• Improved Asset Utilisation
• Traceable Warrantees
• Reliable and Accurate
• Information Rich
• Enhance Security
• Robust and Durable
• Improved Inventory Management


DISADVANTAGES OF RFID

• Cost of Tags
• Cost of new Infrastructure
• Lack of Training
• Limited Knowledge
• Immature Technology
• Deployment Issues
• Interference Limitations
• Lack of Ratified Standards
• Concern of Return on Investment
• Requirement of Close Co-operation
• Between Supply Chain Partners