A primer for a key ubicomp technology

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Radio Frequency Identification(RF ID)

• A primer for a key ubicomp technology

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Agenda

• What is RFID?
• Why is it interesting?
• Basic Components
• How it works
• Variety of solutions
• Design issues
• Technology perspective
• Human perspective (todays readings)

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Some resources

• Your classmates
• Meghna Krishnan Bessie Yang
• Osman Ullah Rahul Nair
• Peter Jensen knows a lot as well
• The Web
• http//www.aimglobal.org/technologies/rfid/
• http//electronics.howstuffworks.com/smart-label.h
  tm

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What is RFID?

• Radio Frequency Identification
• A wireless means of communicating data at
  interesting locations
• Contrast with WLAN or WPAN
• We will be covering these next

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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.

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Basic Components

• Every RFID system is composed of
• Tags/transponders
• Powered (active) or unpowered (passive)
• Readers/interrogators
• Antenna attached to reader

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How it works(active propagation coupling)

• Tags have
• Microprocessor memory
• Metal coil (antenna)
• separate power source
• Communication between reader antenna and tag is
  similar to wireless LAN communication.

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How it works( passive inductive coupling)

• Tags have
• Microprocessor memory
• Metal coil (antenna)
• No separate power source
• Readers antenna generates a magnetic field,
  inducing a voltage in the tags antenna, giving
  it energy to perform a return communication,
  modulated over carrier frequency.

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Different kinds of RFID

• Frequency range for carrier signal
• Regulated differently around the world
• Low
• 100-500 kHz
• Medium
• 10-15 MHz
• High (microwave)frequencies
• 850-950 MHz
• 2.4-5.8 GHz

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Design IssuesTechnological

• Range
• Shorter with passive vs. active
• Shorter with lower carrier freq
• Affected 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)

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Other Technological Issues

• Read and/or Write
• Cost
• Low mid are relatively inexpensive
• Especially on a per-read basis
• Health
• ??, but looks to be OK because of RF regulation

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Application Areas

• Tracking valuable assets
• Transportation
• Manufacturing and Processing
• Security
• Animal tracking
• Many in HCI area interested in other uses

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Design IssuesHuman Perspective

• RFID looks promising for implicit interaction.
• It is a fairly robust sensing technology.
• Design challenge
• Getting reads when and where you want them
  without requiring awkward interactions by humans

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Aware Home Example Digital Family Portrait

• Mynatt Rowan
• If you lived next door
• What was today like?
• Is today unusual?
• Did Mom go to church today?
• Goal Provide peace of mind for adult children
• Approach Visualization to summarize daily
  activity and long-term trends

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DFP more details

• Design
• Communicate movement trends
• Technology
• Room-level location

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Room-level location with RFID

• Custom floor mats
• Below-knee tags
• Room-level positioning

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Other uses of RFID in HCI

• Implicit interaction
• Want et al., CHI 99
• Schmidt et al., ISWC 2000