RFID over Wi-Fi

Contributed by Kathy Vogler, PerryProTech

Radio Frequency Identification, RFID, is a system used for tagging and identifying mobile objects and works through a small piece of hardware called an RFID chip.  The chips actually include an antenna to transmit and receive radio signals.  These systems were originally developed as an alternative to barcodes.  RFID allows objects to be scanned at greater distances, tracks information per the unique device and supports storing of data.

This is not a new technology but in fact stemmed from espionage tools used by the Soviet Union during WW2 as a covert listening device that retransmitted radio waves with audio information.  A similar technology was used by the allies and Germany to identify aircraft as friend or foe.  This led to the patent of a passive radio transponder with memory back in 1973 that was first used as a toll device.

Wi-Fi based RFID is big business and expected to grow 100 percent annually.  From the primary usage in manufacturing, transportation and logistics, DoD and retail; increased Wi-Fi adoption has led to RFID over Wi-Fi and brought location and asset tracking to additional areas such as healthcare.  RFID tags can be used to track and manage inventory, assets, people, cars, computer equipment, mobile phones, airport baggage and even pets.  The RFID market increased by 115% from 2013 to 2014 with a net worth of $8.89 billion and is expected to grow to $27.31 billion by 2024.

The nuts and bolts of RFID

The system uses tags or labels attached to the object to be tracked and a two-way radio transmitter-receiver (called a reader) sends a signal to the tag and then reads it’s response. Readers can be Active in two flavors, active reader passive tag by transmitting signals and receiving replies from passive tags and active reader active tag that receive a signal from an active tag.  Another version of this is a battery assisted tag that acts like a passive tag but is powered by a small battery.

Passive tags cost less to make than active tags, require no maintenance and are often used by retailers and open-loop supply chains to track units, cases and pallets.  Semi-passive tags use a built-in battery to provide power to communicate with ancillary support circuits such as temperature monitoring.

A beaconing active tag is most often used in RFID over Wi-Fi for Real-Time Location System, RTLS.  This type of tag sends a short message at a pre-programmed interval to provide location updates.  When items like this travel outside of their enterprise they may require a multimode tag that is the equivalent of having the asset equipped with multiple tags in the same physical tag package.  An example would be reusable shipping containers that are tracked through manufacturing to distribution to a retailer.

Signaling between the tag and the reader is done in multiple ways depending on the frequency band used by the tag.  Tags can be read if passed near a reader, even if the tag is not visible or covered by another object.  Readers are capable of reading hundreds of tags at a time.

Near Field Communications, NFC, is the technology that is bringing payment options to your devices.  Google included this technology in Android and Samsung and now Apple Pay is offering this through the iPhone 6 and Apple Watch.  This is a contactless technology that operates between 4 and 10 centimeters, or less than 3.9 inches. NFC uses electromagnetic radio fields to communicate which is different than Wi-Fi or Bluetooth that uses radio transmissions but NFC is compatible to both. The important key to adoption of NFC technology is the creation of NFC integrated circuitry or chips. And this evolution brings RFID over Wi-Fi to finance.  And, with that, a basic need for security.  In this case, it is best practice to have the data encrypted using AES standards.  You will not want a third party device eavesdropping and stealing your credit card transaction data.  And, if your NFC enabled device is lost or stolen you will not want to risk your credit identity to theft.

Most passive tags and readers now speak the same language (EPCglobal Gen2) and many wireless network providers are making active tags that use Wi-Fi instead of transmitting on dedicated RFID frequencies.  The advantage is that RFID can use the same wireless network already in place for the communications.  It will be interesting to watch the adoption of RFID over Wi-Fi and to realize the value of keeping your existing infrastructure in place with a wide open research and development opportunity and the adoption of new chips and tracking systems.

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