1. Mobile Computing
Lecture Materials By
Bintang Eka Putera

2. Radio-Frequency Identification (RFID)
WHAT IS RFID?
RFID stands for Radio-Frequency Identification
The acronym refers to small electronic devices that consist of a small chip and an antenna.
Capable of carrying 2,000 bytes of data or less
Uses electromagnetic fields to automatically identify and track tags attached to objects

3. Advantages than Barcode
Does not need to be positioned precisely relative to the scanner
Work within a few feet (up to 20 feet for high-frequency devices) of the scanner
Able to query all of the RFID devices within coverage area
Available for more than fifty years

4. Common Problems with RFID
Reader collision
Occurs when the signals from two or more readers overlap
The tag is unable to respond to simultaneous queries
Tag collision
Occurs when many tags are present in a small area

5. Other Problems? Technical problems
RFID Standards
Implemented in different ways by different manufacturers
Easily disrupted
Easy to jam using energy at the right frequency
Security, privacy and ethics problems
RFID tags can be read without your knowledge
RFID tags can be read a greater distances with a high-gain antenna
Can be read after the item leaves the supply chain
Allows anyone to see the contents of your purse or pocket as you walk down the street
Some tags can be turned off when the item has left the supply chain
RFID tags are difficult to remove
New technologies allow RFID tags to be "printed" right on a product and may not be removable at all

6. How does RFID work?
A Radio-Frequency IDentification system has three parts
A scanning antenna
Puts out radio-frequency signals in a relatively short range
The RF radiation does two things:
It provides a means of communicating with the transponder
It provides the RFID tag with the energy to communicate
can be permanently affixed to a surface (handheld antennas are also available)
detects the activation signal from the antenna. That "wakes up" the RFID chip, and it transmits the information on its microchip to be picked up by the scanning antenna
A transceiver
A decoder to interpret the data
A transponder (the RFID tag)
Programmed with information
Do not need to contain batteries, and can therefore remain usable for very long periods of time (maybe decades)

7. RFID Part: Scanning Antenna
Puts out radio-frequency signals in a relatively short range
The RF radiation does two things:
It provides a means of communicating with the transponder
It provides the RFID tag with the energy to communicate
Can be permanently affixed to a surface (handheld antennas are also available)
Features:
RFID Tag detects the activation signal from the antenna.
Activation Signal "wakes up" the RFID chip, and it transmits the information on its microchip to be picked up by the scanning antenna

8. RFID Part: Transceiver
A decoder to interpret the data
Function similarly to RFID readers
Cabled to a programmable logic controller (PLC) or computer via an IO module
The PLC or computer then instructs the RFID transceiver to recode or rewrite the tag if necessary

9. RFID Part: Transceiver cont.

10. RFID Part: Transponder (RFID tag)
Programmed with information
Can therefore remain usable for very long periods of time (maybe decades)
Need not be on the surface of the object (and is therefore not subject to wear)
The read time is typically less than 100 milliseconds
Large numbers of tags can be read at once rather than item by item

11. RFID Part: Transponder (RFID tag) cont.

12. RFID Part: Transponder (RFID tag) cont.
Consist in 2 type:
Active Tags
have their own power source
the reader can be much farther away and still get the signal
10 year life span or less
Passive Tags
do not require batteries
can be much smaller
have a virtually unlimited life span

13. RFID Part: Transponder (RFID tag) cont.

14. RFID Part: Transponder (RFID tag) cont.

15. Zombie RFID Tags?
A tag that can be temporarily deactivated when it leaves the supply chain
Special device can sends a signal to the RFID tag to "die." (no longer readable)
Special device especially made for that kind of tag "re-animates" the RFID tag, allowing the item to reenter the supply chain.

16. Implementations Animal tracking tags
inserted beneath the skin, can be rice-sized
Tags can be screw-shaped to identify trees or wooden items
Credit-card shaped for use in access applications
The anti-theft hard plastic tags attached to merchandise in stores are also RFID tags.
Heavy-duty 120 by 100 by 50 millimeter rectangular transponders are used to track shipping containers, or heavy machinery, trucks, and railroad cars
Airport baggage tracking logistics

17. Frequencies Band Range Data speed Common uses
kHz (low frequency)
10 cm
Low
Animal identification; factory data collection; auto keys
13.56 MHz (high frequency)
10 cm - 1 m
Low to moderate
Smart cards; shelf inventories; transactions
433 MHz (ultra-high frequency) m
Moderate
Defense applications; tracking pallets
Eurasia: 865—868 MHz (ultra-high frequency)
North America: 902—928 MHz (ultra-high frequency) m
Moderate to high
Inventory; hard-to-read RFID applications
MHz (microwave)
1 - 2 m
High
WLAN, Bluetooth standards
GHz (microwave)
>200 m
Road toll accounts

18. Variety Passive Reader Active Tag (PRAT)
system has a passive reader which only receives radio signals from active tags (battery operated, transmit only)
can be adjusted from 1–2,000 feet (0–600 m)
Active Reader Passive Tag (ARPT)
system has an active reader, which transmits interrogator signals and also receives authentication replies from passive tags
Active Reader Active Tag (ARAT)
system uses active tags awoken with an interrogator signal from the active reader

19. Thank you