RFID: Directions and Applications

Transcription

1 RFID: Directions and Applications Miodrag Bolic Associate Professor School of Information Technology and Engineering University of Ottawa, Canada

2 Objectives of this Presentation Improvements or new directions in active RFID Passive UHF RFID Focus on long-range RFID systems 2

3 Outline RFID Introduction Directions - UHF RFID systems UHF near field systems Tag-talk-first technology Semipassive UFID Directions Active RFID Rubee, Dash7 Real-time locating system (RTLS) 3

4 What is RFID? Radio Frequency IDentification - RFID is a wireless technology that uses radiofrequency waves to transfer data between a reader and a tagged item to identify, categorize and track the items. Identification Every item will have a unique identification number Radio frequency 4

5 Radio waves ELECTRO MAGNETIC SPECTRUM LF HF UHF MICROWAVE LIGHT XRAYS AM FM. TV CELL RADAR InfraRed Rainbow UltraViolet 2.45 GHz MHz 5

6 Components of RFID systems Host Computer Tags Host Memory Space Customer-Specific Application Software Antenna Application Program Interface (API) RFID API Software (Communicates with the RFID Reader) Reader 6

7 Basic types of tags Active Tag transmits radio signal Battery powered memory, radio & circuitry High Read Range (100 m) Passive Tag reflects radio signal from reader Reader powered Shorter Read Range (1 cm- 10 m) 7

8 Reader Functionality Reader Functionality Constantly poll or interrogate the space Communicate with the tags Translate tag data into events understandable by middleware Resolve physical-layer communication constraints Interface to host computer (RS485, RS232/422, ethernet, , etc) ID: B9.23AE1F.345C4D012 RFID reader antenna tag 1- The Reader sends an interrogation command, which is radiated by the antennas (*) 2- The tag responds to the reader s command by sending its tag identifier 3- The reader communicates the ID read to the host computer B9.23AE1F.345C4D012 8

9 UHF RFID: Reader to tag data link 9

10 UHF RFID: Tag to reader data link 10

11 Problems with RFID technology <100% reliability (reading accuracy) of RFID systems Interference problems Lack of proof that RFID can yield return on investment Cost of implementation appears to be high for sectors with low cost products Lack of standards and interoperability to legacy systems Privacy problems 11

12 Outline RFID Introduction Directions - UHF RFID systems UHF near field systems Tag-talk-first technology Semipassive UFID Directions Active RFID Rubee, Dash7 Real-time locating system (RTLS) 12

13 UHF Near Field UHF tag s antenna that has only one turn Compatible with EPC Gen 2 standard Ability to read all the tags on the items that are close to each other 30 cm reading distance Expensive UHF readers No mobile reader solutions yet 13

14 Tag Talk First Protocol Reader-modulation RFID protocols; Reader-Talks-First [RTF] change the tag state to optimise read performance request data or state from the tag write data to the tag Tag talk first is a non-reader-modulation protocol; Note: only the tags talk, saving all the time when readers talk in RTF

15 Tag talk first benefits Benefits: Capable of reading tags moving at a high speed Tags are very simple and have potential to be inexpensive The bandwidth required for the readers to read the tags is minimal. Standard Total ISO D: Tags Only Talk After Listening Tags listen for up to 25 ms to detect modulation signal from the reader before transmitting their Ids. 15

16 Semipassive RFID tags Due to interference caused by materials adjacent to the tag, passive tag chips may not harvest enough energy to wake up. Battery assisted RFID tags The RF circuitry can be optimized only for bacscattering Long range Sensor integration Compatible with EPC Global Class 1 Generation 2 UHF RFID 16

17 Semipassive RFID chip UHF (860 MHz MHz) RFID ASIC ISO C (Gen2) and D (TOTAL) compliant 4096-bit non-volatile memory (EEPROM) Coordinated Universal Time Clock (UTC) Integrated temperature sensor Programmable monitoring and alarm conditions for temperature sensor Input for tamper detection Serial Peripheral Interface (SPI) Bus 17

18 Outline RFID Introduction Directions - UHF RFID systems UHF near field systems Tag-talk-first technology Semipassive UFID Directions Active RFID Rubee, Dash7 Real-time locating system (RTLS) 18

19 RuBee IEEE IEEE Standard for Long Wavelength Wireless Network Protocol Near field, inductive coupling Frequency: 130kHz Active battery operated systems Long battery life Goals: asset visibility, reliable reads near metal and water, good security, long read range 19

20 Rubee technology Possible scenario Reader Antenna Tag 1 Tag 2 Tag 4 Tag 3 20

21 DASH7 Developers Alliance for Standards Harmonization of ISO Wireless Data Technology Alliance formed in 2009 Low power Mandated by the U.S Department of Defense Range is scalable, m 433MHz 28kbps 21

22 Dash7:Tag and Reader Features The tags Support a static data transfer rate of at least 9.6kbps Have replaceable batteries and a five year battery life Have an omni-directional internal antenna Have multiple attachment methods New standard (Mode 2): tag-to-tag communications sensor event triggers hybrid active/passive solutions The readers Have a read/write range of 300 feet Be capable of managing 250 transponders within their operating range Be capable of collecting data from a transponder moving at 40Km/h 22

23 Localization Goal is to find position of UHF passive and semipassive tags Active tags Applications Finding items in stores and stocks Locating people carrying the tags Approaches Time of arrivals Time difference of arrivals Angle of arrivals Proximity detection Mapping approach 23

24 Localization Problems with Current Methods Time of Arrival, Time Difference of Arrival and Angle of Angle techniques cannot be used efficiently for indoor location sensing They generally require direct path signal reception and perform poorly in complex multipath situations. 24

25 Radio map matching Scene analysis RF fingerprinting Granularity 3m for WLAN Two steps the radio scene information or RF fingerprints in the environment are collected to form a radio map unknown tags are localized by matching the measured data corresponding to the unknown tags with an appropriate subset of fingerprints recorded in the radio map The probabilistic methods are to find the location of a tag from multiple possible locations to yield the highest posterior probability. 25

26 What was not covered Dual frequency RFID systems Near field communication Chipless RFID technologies Energy harvesting.. 26