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  1. 1. DILLA UNIVERSITY COLLEGE OF ENGINEERING & TECHNOLOGY School of Computing & Informatics M. Sc in Computer Science & Networking By Chapter-04 COET, Dilla University 1 Course Number CN6117 Course Title Mobile Computing
  2. 2. Mobile Computing CHAPTER-04 • Radio frequency identification(RFID) • Location based services COET, Dilla University 2
  3. 3. Radio Frequency Identification(RFID) 3 COET, Dilla University
  4. 4. Overview • What is RFID? • How RFID Works • Applications 4 COET, Dilla University
  5. 5. What is RFID? • Radio Frequency Identification • The use of radio frequency tags to identify real objects. 5 COET, Dilla University
  6. 6. RFID  Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects.  An RFID system consists of a tiny radio transponder; a radio receiver and transmitter.  When triggered by an electromagnetic interrogation pulse from a nearby RFID reader device, the tag transmits digital data, usually an identifying inventory number, back to the reader.  This number can be used to track inventory goods. 6 COET, Dilla University
  7. 7. Identification • Assign IDs to objects • Link the ID to additional information about the object • Link the ID to complementary info 7 COET, Dilla University
  8. 8. Identification Examples • Bar Codes • License Plates • Social Security Numbers • Student ID • Serial Numbers • Car Keys • Database Keys 8 COET, Dilla University
  9. 9. How Does RFID Work? • 3 Components – Transceiver – Tag Reader – Transponder – RFID tag – Antenna 9 COET, Dilla University
  10. 10. RFID Hardware Magnetic / Inductive Coupling Transceiver Tag Reader antenna RFID Tag IC or microprocessor antenna 10 COET, Dilla University
  11. 11. RFID Hardware Propagation Coupling Transceiver Tag Reader antenna RFID Tag IC or microprocessor antenna 11 COET, Dilla University
  12. 12. Types of Tags • Passive Tags – No battery – Low cost • Active Tags – On-board transceiver – Battery – must be replaced – Longer range – High cost 12 COET, Dilla University
  13. 13. Passive tags & Active tags There are two types of RFID tags: Passive tags are powered by energy from the RFID reader's interrogating radio waves. Active tags are powered by a battery and thus can be read at a greater range from the RFID reader; up to hundreds of meters. 13 COET, Dilla University
  14. 14. Readers RFID systems can be classified by the type of tag and reader.  A Passive Reader Active Tag (PRAT)  Active Reader Passive Tag (ARPT)  Active Reader Active Tag (ARAT) 14 COET, Dilla University
  15. 15. Readers RFID systems can be classified by the type of tag and reader.  A Passive Reader Active Tag (PRAT) • A Passive Reader Active Tag (PRAT) system has a passive reader which only receives radio signals from active tags (battery operated, transmit only). • The reception range of a PRAT system reader can be adjusted from 1– 2,000 feet (0 – 600 m) , allowing flexibility in applications such as asset protection and supervision.  Active Reader Passive Tag (ARPT) • An Active Reader Passive Tag (ARPT) system has an active reader, which transmits interrogator signals and also receives authentication replies from passive tags. 15 COET, Dilla University
  16. 16. Cont.. Active Reader Active Tag (ARAT) • An Active Reader Active Tag (ARAT) system uses active tags awoken with an interrogator signal from the active reader. • A variation of this system could also use a Battery-Assisted Passive (BAP) tag which acts like a passive tag but has a small battery to power the tag's return reporting signal. 16 COET, Dilla University
  17. 17. Types of Tags • Read Only – factory programmed – usually chipless • Read / Write – on-board memory – can save data – can change ID – higher cost 17 COET, Dilla University
  18. 18. Real Tags 18 COET, Dilla University
  19. 19. Data Transfer • Amplitude Modulation (AM) • Frequency Shift Keying (FSK) • Phase Shift Keying (PSK) 19 COET, Dilla University
  20. 20. Amplitude Modulation (AM)  Amplitude modulation is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio carrier wave.  In amplitude modulation, the amplitude of the carrier wave is varied in proportion to that of the message signal, such as an audio signal. 20 COET, Dilla University
  21. 21. Frequency Shift Keying  Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal.  The technology is used for communication systems such as telemetry, weather balloon radiosondes, caller ID, garage door openers, and low frequency radio transmission in the VLF(Very low frequency) and ELF(Extremely Low Frequency) bands. The simplest FSK is binary FSK (BFSK).  BFSK uses a pair of discrete frequencies to transmit binary (0s and 1s) information.  With this scheme, the 1 is called the mark frequency and the 0 is called the space frequency. 21 COET, Dilla University
  22. 22. Cont.. • Fc/8/10 – 0’s are the carrier divided by 8 – 1’s are the carrier divided by 10 • Count clock cycles between changes in frequency • Slows the data rate • Provides for a simple reader design • Fair noise immunity 22 COET, Dilla University
  23. 23. Phase Shift Keying  Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave).  The modulation is accomplished by varying the sine and cosine inputs at a precise time. 23 COET, Dilla University
  24. 24. Cont.. • One frequency – Change the phase on the transition between a 0 to 1 or 1 to 0 • Faster data rate than FSK • Noise immunity • Slightly more difficult to build a reader than FSK 24 COET, Dilla University
  25. 25. Multiple Tags? • What happens when multiple tags are in range of the transceiver? • All the tags will be excited at the same time. • Makes it very difficult to distinguish between the tags. 25 COET, Dilla University
  26. 26. Collision Avoidance • Similar to network collision avoidance • Probabilistic – Tags return at random times • Deterministic – Reader searches for specific tags 26 COET, Dilla University
  27. 27. Frequency Ranges • Low – 100-500 kHz – short range, low data rate, cost, & power • Intermediate – 10-16 MHz – medium range and data rate • High – 850-950 MHz & 2.4-5.8GHz – large range, high cost, high data rate • 8 total ranges around the world • No standards … yet 27 COET, Dilla University
  28. 28. Frequency Trade-Offs Frequency  Power  Cost  Bandwidth  Line of Sight 28 COET, Dilla University
  29. 29. RFID can be used in a variety of applications such as: o Electronic key for RFID based lock system o Access management o Tracking of goods o Tracking of persons and animals o Toll collection and contactless payment o Machine readable travel documents o Smart dust (for massively distributed sensor networks) o Locating lost airport baggage 29 COET, Dilla University
  30. 30. Cont.. o Timing sporting events o Tracking and billing processes o Monitoring the physical state of perishable goods o Passive / Secure Entry o Airline Baggage Tracking o Postal Package Tracking o Time and Attendance 30 COET, Dilla University
  31. 31. Who’s got an RFID tag with them right now? 31 COET, Dilla University
  32. 32. Security • RFID used to grant entry to secure areas • Tracks time and movement of people • Dynamically change access codes • Provide automated entry 32 COET, Dilla University
  33. 33. Livestock Tagging Meet Bobby the Cow Bobby has an old fashioned ear tag for identification. 33 COET, Dilla University
  34. 34. Tracking Penguins http://www.beitec.com/penguin.htm 34 COET, Dilla University
  35. 35. Automated Toll Collection 35 COET, Dilla University
  36. 36. Package Tracking Picture courtesy Texas Instruments 36 COET, Dilla University
  37. 37. Potential Applications • Smart Grocery Store • Smart Kitchen • Smart Sitterson 37 COET, Dilla University
  38. 38. Smart Grocery Store • Every item in the store already has a bar code. • Why not use an RFID tag? • Speed up checkouts 38 COET, Dilla University
  39. 39. Smart Grocery Store • Several carts this full in early evening could seriously slow down the checkout process. • How much do cashiers cost? 39 COET, Dilla University
  40. 40. Smart Grocery Store • Add an RFID tag to all items in the grocery. • As the cart leaves the store, it passes through an RFID transceiver • The cart is rung up in seconds. 40 COET, Dilla University
  41. 41. Smart Groceries Enhanced • Track products through their entire lifetime. Diagram courtesy How Stuff Works 41 COET, Dilla University
  42. 42. Smart Fridge • Recognizes what’s been put in it • Recognizes when things are removed • Creates automatic shopping lists • Notifies you when things are past their expiration 42 COET, Dilla University
  43. 43. RFID Chef • Uses RFID tags to recognize food in your kitchen • Shows you the recipes that most closely match what is available 43 COET, Dilla University
  44. 44. Smart Sitterson • Tag locations throughout Sitterson • User walks around with handheld and transceiver • RFID tags point the handheld to a webpage with more information about their location or the object of interest 44 COET, Dilla University
  45. 45. RFID’s Advantages • Passive – wireless • Store data on a tag • Can be hidden • Work in harsh environments • Low cost 45 COET, Dilla University
  46. 46. RFID’s Disadvantages • Lack of standards • Short range 46 COET, Dilla University
  47. 47. References RFID Chef http://www.inf.ethz.ch/vs/res/proj/rfidchef/ AIM Global Network http://www.aimglobal.org/technologies/rfid/what_is_rfid.htm Texas Instruments RFID Solutions http://www.ti.com/tiris/default.htm Interaction Design Institute RFID Whitepaper http://people.interaction-ivrea.it/natasha/rf/RFID_research.pdf Auto-ID Center http://www.autoidcenter.org/ Cow Jewelry – or – Revolution http://www.cs.unc.edu/~sparkst 47 COET, Dilla University
  48. 48. Thank you 48 COET, Dilla University

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