Radio Frequency Identification

(RF ID)

Agenda

What is RFID?Why is it interesting?

Basic ComponentsHow it worksVariety of solutions

Design issuesTechnology perspectiveHuman perspective (today’s readings)

What is RFID?Types of Radio Frequency Identification:

Passive and Active

RFID is a wireless means of communicating data at interesting locations

Contrast with WLAN or WPAN

A Passive RFID system consists of:

RFID tags

RFID reader

Middleware.

The identification of the RFID tag takes place

by the reader over the wireless medium or air

Components of an RFID System

Where is the POWER of the Passive RFID?

S-Shaped Antenna RFID

Other Form of Antenna RFID

Passive tags find several applications in the fields of:

• Logistics such as in manufacturing, warehousing, and distribution systems;• Security in libraries and bookstores, passports, and airports;• Transportation in automatic vehicle identification, electronic toll collection, and electronic vehicle registration.

Middleware is the software component between the RFID reader hardware and RFID application software.

RFID middleware :filters, formats, and converts low-level RFID hardware communication with the tags into usable event information, so that the data can be processed by a software application.

RFID Middleware

In an RFID system, middleware translates machine information into tag event information, like:“reader reads a tag.” This information can include some other useful parts depending on the specific reader model used, such as tag ID, zone ID, and time stamp. The reader generates huge amounts of such event information.

Ubicomp - Spring 2003

Why is RFID interesting?

Cost-effective means of tracking assets

Becoming price competitive

Readings for today motivate different kinds of ubicomp applications for practical sensing.

Basic Components

Every RFID system is composed of:

Tags/transpondersPowered (active) or unpowered (passive)

Readers/interrogatorsAntenna attached to reader

How it works(active propagation coupling)

Tags have Microprocessor + memoryMetal coil (antenna)separate power source

Communication between reader antenna and tag is similar to wireless LAN communication.

How it works( passive inductive coupling)

Tags have Microprocessor + memoryMetal coil (antenna)No separate power source

Reader’s antenna generates a magnetic field, inducing a voltage in the tag’s antenna, giving it energy to perform a “return” communication, modulated over carrier frequency.

Different kinds of RFID

Frequency range for carrier signalRegulated differently around the world

Low100-500 kHz

Medium10-15 MHz

High (microwave)frequencies850-950 MHz2.4-5.8 GHz (UWB)

Design Issues:Technological

RangeShorter with passive vs. activeShorter with lower carrier freqAffected by antenna and

surrounding environment (water, humans)

Affected by relative orientation of antenna-tag

Usually do not require line of sight (except for high freq)

Other Technological Issues

Read and/or Write

CostLow & mid are relatively

inexpensiveEspecially on a per-read basis

Health??, but looks to be OK because of RF

regulation

Application Areas

Tracking valuable assetsTransportationManufacturing and ProcessingSecurityAnimal tracking

Design Issues:Human Perspective

RFID looks promising for implicit interaction.

It is a fairly robust sensing technology.

Design challengeGetting “reads” when and where

you want them without requiring awkward interactions by humans

Digital Family Portrait: more details

DesignCommunicate movement trends

TechnologyRoom-level location

Room-level location with RFID

Custom floor mats:To Detect the entrance

Below-knee tags

Ubicomp - Spring 2003