WT Week 11

Wireless PAN I - RFID

tldr - WPAN, RFID components, applications and pros & cons

Personal Area Network (PAN)

Interconnection of computing devices within the range of an individual

PAN?

• To communicate among personal devices
• To connect to higher level network or internet
• Wired with computer buses such as USB & FireWire

Problems?

• Different devices require varying types of cables
• Wires and connector problems
  • Complex wiring
  • Broken, misconnected or defective wires

Wireless PAN (WPAN)

Low-cost networking scheme that enables computing devices to wirelessly connect with each other over short distances

Features

• Short range
• Low power
• Small in size
• Low cost
• Stay connected while moving around
• Batteries instead of plugs

Radio Frequency Identification (RFID)

Automatic contact-less identification and data capture using Radio Frequency (RF) signal

• Each RFID device holds a small amount of unique data (i.e. serial number)
• The device can be read from a distance
  • No contact or line-of-sight necessary

RFID Frequency Range

RFID uses different frequency ranges (VLF to UHF)

Very Low Frequency (VLF)

• 30 KHz - 500 KHz
• Short reading ranges
• Lower system costs

Examples

-Security access, asset tracking, animal identification etc.

Ultra High Frequency (UHF)

• 850 MHz - 950 MHz & 2.5 GHz - 2.5 GHz
• Long reading ranges
• High reading speeds
• Higher system costs

Examples

• Supply chain, railroad car tracking, toll collection etc.

RFID System

Consists of 3 components

• Tags (Transponder)
• Reader and antenna (Transceiver)
• Processing Unit / Back-end server

How it works

1. Reader (Transceiver) emits RF signal
2. Reader creates electromagnetic field
3. Electromagnetic field induces a current in tag (transponder)
4. Tag generates low-powered wireless response
5. Data captured by reader is sent to server

RFID Tags

Each tag has an id code called EPC (Electronic Product Code)

Active Tags

• Power: Battery operated
• Price: More costly
• Range: Long
• Lifespan: Long battery life

How it works

Continuously broadcasts its own signal

Usage

Tracking high-value goods

Passive Tags

• Power: No battery required
• Price: Less costly
• Range: Short
• Lifespan: Extremely long life

How it works

Induces energy from RFID reader

1. Receive signal from transceiver
2. Power on chip
3. Broadcast info on EPC

Usage

Tracking high-volume goods

Semi-Active Tags

• Power: Battery for chip circuitry
• Price: More expensive than passive tags
• Range: Shorter range than active tags

How it works

Chip’s circuitry powered by battery but communicates by drawing power form reader’s RF waves.

Usage

Tracking high-valued goods that need to be scanned over long ranges

RFID Reader

Uses radio waves to read RFID tags

Types

• Stationary
• Mobile

Applications

• Volatile chemicals
• High-value goods that need to be scanned over long ranges
• Fast-moving goods that are not of great value

Credit Card Contactless Payment

• Allow users to wave card over reader at POS
• Reader sends RF waves to energise the embedded RFID chip in card
• RFID chip transmits data to reader through its antenna
• Reader sends info to bank for verification
• Transaction approved upon verification

Security Concerns

• RFID credit cards may be subject to hacking
• Hacking device placed near the card could activate signal on RFID chip and receive card details
• Since payment does not require signature or pin, stolen cards can be easily used to make payments
• RFID chip can be cloned

RFID Considerations

• Cost
• Privacy (turning off the tag)
• Multiple data collection
• RF Interference
• Anti-collision
• UHF bounces off metal and gets absorbed by water

Advantages & Disadvantages

Advantages

• Low cost
• Compact size
• Line-of-sight not required

Disadvantages

• Limited computation power & range
• Non-standardisation
• Prone to reader / tag collision

Barcode vs RFID

fin