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INFORMATION PAPER
                                         International Journal of Recent Trends in Engineering, Vol 1, N...
INFORMATION PAPER
                                                     International Journal of Recent Trends in Engineeri...
INFORMATION PAPER
                                                           International Journal of Recent Trends in Eng...
INFORMATION PAPER
                                                 International Journal of Recent Trends in Engineering, ...
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A Survey of RFID Tags

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A Survey of RFID Tags

  1. 1. INFORMATION PAPER International Journal of Recent Trends in Engineering, Vol 1, No. 4, May 2009 A Survey of RFID Tags M Ayoub Khan, Manoj Sharma, Brahmanandha Prabhu R Communications Research Centre, SoE Center for Development of Advanced Computing (CDAC) (Ministry of Communications and I.T., Govt. of India), Noida, India Email: {ayoub, manojsharma, brahmanandha} @cdacnoida.in Abstract—The Radio Frequency Identification System size of the tag (form factor) has also an important role in (RFID) has become a popular system and its applications size constraint applications. Researchers are putting has reached in most of the fields like toll bridge, supply consistent efforts to reduce the size of tag. Presently, they chain management and defense sector [8]. The RFID has have achieved such a small tag that is very much smaller also entered into the field of medical sciences [4, 7]. Everyday, RFID tags are becoming very small and their than a human hair. Recently, Hitachi has developed dimensions are also reducing to 0.002 inches (RFID powder world’s smallest RFID tag with the size of 0.05x0.05mm tag) developed by Hitachi [10,11]. There are many different [9](0.002inch) named, as RFID powder [10,11]. The types of RFID tags available in the market for different "powder type" tags are sixty four times smaller as types of applications. Due to reduction in the cost of compared to the previous µ-type RFID tags [15]. The production, RFID systems are being deployed everywhere in RFID powder has inbuilt memory of 128 bit ROM; it has large number. Therefore, it becomes important to the storage capacity of 38 bit identification number for a understand the tag technology and their applicability. In particular tag. this paper, we provide a comprehensive survey of various This paper is organized as follows: an introduction to RFID tag technologies reported in the literatures and classify them into different categories. RFID tag is technology and classification is presented in section II. Section III described working principal, Index Terms—RFID, Active tag, Passive tag, Semi-Passive communication techniques and detailed schematic. The tag, Digestive tag, EPC application of RFID technology along with the suitability of particular tag type is discussed in section IV. Finally, a I. INTRODUCTION conclusion is discussed in the section V The Radio Frequency (RF) technology has a wide area of applications like television, radio, cellular phones, II. TAG TECHNOLOGY AND CLASSFICIAITON radar, medical and automatic identification systems. The An RFID tag is a microchip combined with an antenna RFID technology was invented in 1948, but the system in a compact package as show in figure 1[4]. The commercial products based on RFID came in 1980s only. microchip contains memory and logic circuit to receive The radio waves used in RFID are Low Frequency (LF)- and send the data back to the reader. The antenna receives 125 KHz to 143 KHz, High Frequency (HF) 3MHz to 30 signal from an RFID reader and then backscatters the MHz, Ultra High Frequency (UHF) 300MHz to 1 GHz, signal with required data. Microwave frequency (MW) > 1 GHz. The RFID is an automatic data capture systems (AIDC) that is a contactless and uses RF signals for communication. The data is stored on silicon chips (tag memory), which has been tagged to the target like books, parcels, human, animal, or other non-living objects. The RFID provides a unique identification number for Antenna identifying the particular objects known as electronic product code (EPC)[12]. The reader sends continuous waves (CW) through which tag drives power supply in order to operate the chip. Microchip RFID tag stores and transmits the data to the reader in a contactless manner using radio waves by a technique Figure 1. RFID Tag known as backscattering. The information can be a The RFID tags can be broadly classified in two product ID or manufacture ID of specific product. different categories as follows: The RFID tag consists of an electronic chip to which an 1. Based on ‘on-board’ power supply antenna is attached. Some passive (semi) tag contains a 2. Based on capacity to rewrite the data battery, to supply the power to auxiliary electronic However, we have classified the tag based on various circuit. The tag plays very important role in any RFID parameters like Identification format, frequencies, and application. There are various methods to classify a tag form factors etc. as shown in table 1. There are tags based on their characteristics. The tag is distinguished available in the market, which are digestible in the human based on power source, frequency and functionality. The body. Theses tags are used in medical diagnosis. The tag 68 © 2009 ACADEMY PUBLISHER
  2. 2. INFORMATION PAPER International Journal of Recent Trends in Engineering, Vol 1, No. 4, May 2009 can be classified into two or more categories viz. based tag depend on the VLSI and communication on power source, based on form factor, based on protocol/technologies. Each tag has different data rate, operating frequency etc. read capability, memory, cost and life mentioned in TABLE 1.TAG CLASSIFICATION CRITERIA table 2. We have another classification that is based on the Criteria Types content and format of the information. This classification Identification format 64-Bit EPC Tag, 96-Bit EPC Tag, is based on EPCGlobal standard as shown in table 3[12]. 128-Bit EPC Tag etc The EPC classification has potential to change the way Power Source 1. Passive 2. Semi-passive many companies do business operations to meet the 3. Active standard and allow business to share information Frequencies LF, HF, UHF effectively. Functionality 1. Memory (Size, Read/Write) TABLE 3.EPC CLASS STRUCTURE 2. Environmental sensors 3. Security functionality EPC Class Definition Programming Form Factor 1. Size/Shape of the tag Class-0 Gen-1 Read Only, Passive tags Programmed by 2. Digestible, implantable the factory 3. Weight of the tag Class-1 Gen-1 Write-Once, Read- Programmed once 4. The method by which the Many, Passive tags by the user then tag is affixed locked Class-1 Gen-2 Write-Many, Read- Programmed once In general, we classify the tag into passive and active Many, passive tags. by the user then categories. The passive tag has no ‘on-board’ power locked Class-2 Rewritable passive tags source. They extract power from the signal (CW) sent by with extra functionally the reader that is used to operate the chip. The absence of like encryption, battery makes their size smaller. The active tag has ‘on- emulation [3] board’ power source. This ‘on-board’ power source is Class-3 Semi-passive tags that Re-programming supports broadband used to transmit the data from the tags to the reader, and communications this power is also a source for other electronics Class-4 Active tags that can components of the tags present in the tag. In the passive communicate to other tag, the reader initiates the communication whereas in peers. active tag, the tag initiates the communication. A semi- Class-5 Readers, they can power other tag of class (I, II, passive tag is passive in nature, but it contains a battery to III) and as well can Not applicable supply power to auxiliary components like sensors, user communicate to class IV interface etc. A tag generally operates in three main wirelessly. frequencies as mentioned in table 1. The classification of tag based on the format, reader/write TABLE 2.TAG CHARACTERISTICS capability and programming capability is as shown in table 3. The EPC classification consists of Class and Characteristics Passive RFID Active RFID Semi- Passive Generation. The Class describes a tags basic functionality RFID for example whether it has memory or an on-board power Frequency 860MHz -960 868/915MHz 868/915M source whereas Generation refers to a tag specification's (UHF) MHz and 2.4 GHz Hz and 2.4 major release or version number. GHz Internal Power No Yes Yes Bit Rate (Kbps) 246 20/40/250 16 III. TAG ARCHITECTURE Memory (KB) 128 128 4 Multi –Tag 3 sec. to 1000 tag / 7 tags / sec A. Communications techniques Collection identify 20 sec at 100 at 3 mph The communication flow in the RFID system is in either tags mph the reader-to-tag or tag-to-reader direction depending on Read Range 1-30 ft. 1-300 ft. Up to 15 ft. the type of tag. In passive tag, the EPC/information is Cost INR 10-150 INR.1250- INR 500- sent to the reader by reflecting, or backscattering. A 2500 2000 Life Time 3-10 years ½ -5 years ½ -5 years pictorial representation of transmitted energy between tag and reader is shown in figure 2. The choice of a particular frequency is solely govern by Power for tag and radio Signal the type of applications and read-rang required viz. animal monitoring application requires LF whereas toll- collection requires UHF. The size, shape, weight and Reader Tag physical nature plays very important role in selecting a tag for a particular application. Suppose, we want to Backscattered signal probe the person’s digestive system then it is possible Figure 2. Communication between reader and passive tag [6] through digestive RFID tags only. These edible RFID Unlike passive tag, active tags has ‘on-board’ power tags can be swallowed by patient and get disintegrated in source. This power is used to deliver energy for the body for diagnostic process. The characteristics of the transmitting the data from the tag. This energy is also a 69 © 2009 ACADEMY PUBLISHER
  3. 3. INFORMATION PAPER International Journal of Recent Trends in Engineering, Vol 1, No. 4, May 2009 source for other electronics components of the tags The reader can send read command to read the data from present in the tag. tag’s memory. The communication protocols (EPC Transmitted signal from tag standard) are implemented in the logic circuit of the tag. Reader The clock extract is used to generate the clock in order to Tag Battery synchronize with reader clock. A detailed schematic of passive RFID tag is shown in figure 6. In this, antenna receives electromagnetic field from the readers producing a voltage signal of high frequency Figure 3. Communication between reader and active tag [6] (RF). The voltage is rectified by a diode (which allows The semi-active tag also has ‘on-board’ battery but this current flow in one direction only) and smoothen using a battery is used for driving the auxiliary electronics storage capacitor. This would produce a DC like voltage, (sensors, user-interface etc) circuit only. The data to the which is used to energize the logic unit and the memory reader is sent using backscattering technique. The semi- unit of the passive tags. The other rectification circuit is passive tags, reader always initiates the communications used for extracting the reader data command. For sending as shown in figure 4. the tag data i.e. EPC/ID to the reader, the tag simply Power for tag and radio Signal changes the electrical co-efficient property of the antenna, which changes the signal reflected from the Reader Tag Sensor Battery antenna. This process is called backscattering [1]. In the diagram above, we used a Field Effect Transistor (FET) as a switch when it’s ‘ON’ the antenna is grounded and a large current flows and when the FET is ‘OFF’, a small Figure 4. Communication between reader and semi-passive tag [6] current is allowed to Flow. B. Schematic of tag The active has on-board power supply, control circuitry The passive tag consists of microchip (memory and logic) and transmitter to receive/send the data. A detailed and antenna as shown in figure 5. schematic is shown in figure 7, where tag synthesizes the carrier signal by a local oscillator (LO) and a crystal Demodulator reference. This enables tag to select a specific frequency band using one of modulation technique (ASK, PSK, FSK, QAM) depending upon requirement. The transmit Rectifier Logic power, filter and amplification are used to produce good receive sensitivity, due to which the read range of the tag is measured to be hundreds of meter or more. Clock Extractor Memory DC power Figure 5. Block diagram of passive tag [5] Vdd The Rectifier shown in the figure 5 converts the AC Filter Amp UID power into DC power from reader and the extracted TX Logic Memory power is used for other components of the tag like Modulator User memory/logic circuit etc. in order to interpret the XTAL LO SYN command, the demodulator block demodulates the received signal from the reader. RX Filter Amp Mixer Antenna Radio DC Figure 7. Schematic diagram of Active Tags [6] Power Diode Big capacitance The schematic of semi-passive tag is similar to the Vdd passive tag except the DC power sources is attached for Reader Data UID auxiliary circuit like sensor, user interface etc. in Logic Memory Small capacitance User IV. APPLICATIONS out The RFID technologies are currently considered major enabling technology in IT for automation of supply chain Backscattering management, asset tracking, animal monitoring [2], FET medical applications, warehouse and access control in contactless fashion as shown in table 4. The data 1 0 1 collected from the application contributes quantitative Figure 6. Schematic of passive tag [6] data for IT decision makers. Presently, RFID is not very widespread, but leaading stores like Wal Mart [13], 70 © 2009 ACADEMY PUBLISHER
  4. 4. INFORMATION PAPER International Journal of Recent Trends in Engineering, Vol 1, No. 4, May 2009 K-Mart, Target, BestBuy has discovered that RFID access control, RFID Cashless payment, Electronic technology can keep their inventories at optimal-level, Immobilisation etc) and secondly, medium to long reduce stock-losses, limits shoplifting and speedup the application, where the distance may be much longer (like billing process. Toll collection, Vehicle tracking system etc). TABLE 4.RFID APPLICATIONS Application Area Tag Technology CONCLUSIONS Supply chain automation UHF passive tag used to track the In the presented work, we have discussed various types of consignment in the supply chain Asset tracking HF/UHF passive tag can be used to tag technology that are available in the market. We have track the item in offices, labs, broadly classified tag based on five major criteria. The warehouses, pallets and containers classification based on the EPCGlobal [12] standard is etc. The metal items absorb radio also discussed in detail. Each tag has some strength and waves; therefore special type is required for metal assets tracking. weakness, which are reported in the characteristics of the Medical applications UHF passive tag can be used for tag. The working principle, communication technique and patient monitoring, the drugs, schematic show the data flow of tag. Therefore, biometric measurements and understanding of classification, communication diagnosis using digestive tags. techniques, architecture, application of tag becomes People tracking UHF passive/active tag can be used for the purpose of presence very much useful for end-user as well as for the designer. management or security. Warehouse UHF passive tag can be used for ACKNOWLEDGMENT real-time inventory by automated registration of items in a warehouse The authors would like to thanks Dr. George Varkey, or store-room Executive Director and Dr. N W Nerurkar, C-DAC, Animal monitoring LF implantable passive tag can be used in monitoring the animals [2]. Noida for their encouragement for this work. The authors Toll collection UHF passive/active tag can be used also would like to thank Dr. Arti Noor, C-DAC, Noida for automatic deduction of toll at and Dr. Abhijit Sen, Kwantlen Polytechnic University, highways. Canada for providing constructive comments and help in Access control LF/HF passive tag can be used to improving the contents of this paper. provide access control in the office, stores, or sensitive part of buildings RFID Cashless/Wireless RFID Wireless payment REFERENCES Payment technologies provide a safe way to do business. In these technologies [1] Nikitin, P.V.; Rao, K.V.S “Theory and measurement of no cash is involved, and no wallet backscattering from RFID tags”, Antennas and is required [14]. Propagation Magazine, IEEE Volume 48, Issue 6, Dec. This technology can be used to 2006 pp. 212 – 218 Electronic Immobilisation check the authenticity of the key [2] Pongpaibool, P “A study on performance of UHF RFID for ignition lock. tags in a package for animal traceability application” Sporting Events In large-scale sporting events like 10000 participants, major problem ECTI-CON 2008. Vol. 2, 14-17 May 2008 pp 741 – 744 are calculating exact running time. [3] Khan, M Ayoub, Sharma Manoj, R Brahmanandha Prabhu The tag is attached to the runner’s “FSM based Manchester Encoder for UHF RFID Tag shoes in order to calculate exact Emulator” IEEE ICCCN 2008, Karur, Tamilnadu, pp 1-6 time at the start-line only. [4] K. Finkenzeller, “RFID Handbook: Fundamentals and The interesting the application of RFID has emerged in Applications in Contact less Smart Cards and medical sciences for the diagnosis process. These are the Identification”, John Wiley & Sons; 2 edition, 2003. pp special class of passive tags known as powder or 392 digestible tag [10,11] etc. [5] Sandip Lahiri “RFID Sourcebook” Prentice Hall PTR The digestive tag is used for probing human system. The August 31, 2005 RFID digestive tags are harmless and intentionally [6] The RF in RFID Passive UHF RFID in Practice by Daniel fragile. These tags are covered with a soft gelatin material M Dobkin USA, ISBN 978-0-7506-8209-1 so that it takes some time to dissolve in the stomach. The [7] http://www.rfidjournal.com/article/view/961 Date: March RFID digestible tags are used to monitor digestives tracks 2, 2009 of the stomach, hip joints, knee joints and other human [8] http://www.caen.it/rfid/military_civilian.php Date: March body [9]. These digestive tags will stop working when 2, 2009 they are exposed to the gastric acid for a specific period [9] www.nextnature.net Date: January 06, 2009 of time enabling the experts to monitor the digestive [10] http://www.engadget.com/2007/02/14/hitachis-rfid- function of the patient. powder-freaks-us-the-heck-out/ Date: January 07, 2009 The RFID applications are not limited to the above- [11] http://www.pinktentacle.com/2007/02/hitachi-develops- mentioned area only. This technology can be applied in rfid-powder/ Date: January 07, 2009 any area based on the business process requirement. [12] www.epcglobalinc.org/ Date: Jan 10, 2009 However, we can categorize the applications in into two [13] www.rfidgazette.org/walmart/ Date: Feb 20, 2009 principal categories: firstly, short-range applications [14] www.gilbarco.com/pdfs/P2319.pdf Date: Feb 20, 2009 where the reader and tag must be in close proximity (like [15] www.hitachi.co.jp/Prod/mu-chip/ Date: Feb 20, 2009 71 © 2009 ACADEMY PUBLISHER

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