Radio-frequency identification (RFID) is an all-encompassing term that covers several different frequencies and technologies:
- Passive RFID, which uses high-power readers that emit RF signals to battery-free tags.
- Active RFID, which uses Bluetooth-based tags to communicate location with readers.
- Near-field communication (NFC), a variation of high frequency passive RFID that uses an extremely close-range magnetic field for two-way communication.
Because these three technologies are so closely related, they’re often compared to one another. But interestingly, they have very different use cases based on the their strengths and weaknesses. Below, we’ve outlined the characteristics of each so you can get a better grasp on which technology is viable for your solution. As you’ll see, when it comes to asset location management, active RFID is a real contender in the space.
Passive RFID uses simple, battery-free tags and high-power readers. The reader sends out a low-frequency, high-power RF signal, which transmits so much energy over the air that the tag’s collector antenna picks up the radio waves. This causes electricity to flow in the collector, waking up the tag’s circuit.The tag then transmits back to the reader at a different frequency. This is the type of technology some libraries use to protect their inventory, and department stores use to detect and deter theft.
Passive RFID enables one-directional communication that, with enough energy, can produce a range of several meters. This makes passive RFID ideal for chokepoint RFID (which is what storefronts with large resonators use), but not as useful for asset location management. To be even remotely useful for location positioning, you would need a reader every 10-15 feet (which could get expensive very quickly).
Active RFID uses battery-powered tags that regularly advertise their identity. These tags connect to various access points, which then transfer tagged location data to a gateway. RFID software then uses this data to provide probability estimates of where each reader is located.
Active RFID is the only viable option of these three technologies when it comes to asset location management. Here’s why: An active RFID system provides you with the nearly real-time locations of all tagged assets. Passive RFID, on the other hand, can only provide you with basic inventory data (e.g. “Is X asset in the storage room, or is it not?”). So if you are looking to track capital equipment or monitor visitors and vendors on your property, an active RFID system could be ideal system for your needs.
One major difference between passive and active RFID is battery life. Because passive tags don’t use batteries, they last forever—but the tags in an active RFID system will require new batteries every 3-5 years.
Near-Field Communication (NFC)
NFC is based on the same protocol as RFID—and both passive RFID and NFC operate in the same 13.56 MHz frequency—but the use cases are entirely different. So while NFC is an excellent data transmission and exchange medium, it isn’t appropriate or even remotely viable for asset location management. Here’s why.
In radio communications, “the near field” refers to the area close to an antenna where the magnetic field being produced is detectable. NFC applications need to be within an inch or two (sometimes only a few centimeters) from the reader, which allows efficient transmission of energy.
NFC is almost exclusively used for high-speed data transfer between two electronic systems, like a smartphone and a payment reader in the checkout line, or two smartphones exchanging data, for example.
NFC has two particularly noteworthy features.
First, NFC enables bi-directional communication through dual-mode hardware, so a device can act as both a reader and a tag. For example, you can “bump” two Android phones together and exchange information using the NFC standard, or set up a secure session to exchange crypto for payment.
Second, NFC allows communication from passive tags. For example, when you place your NFC-enabled credit card on a tap-to-pay credit card terminal, the energy from the NFC reader sends a burst of energy and excites the NFC chip in the card. At the same time the reader is verifying the card, the card is ensuring that the reader is valid. This kind of two-way processing isn’t something you can do with passive RFID; when the passive reader sends out a burst of energy, the passive RFID tag can only transmit back a number.
RFID Vs. NFC Costs
It’s difficult to compare RFID (both passive and active) to NFC apples to apples, because the cost often depends on what you’re using the technology for. The NFC chip in your credit card, for example, is roughly equivalent to the cost of a passive RFID tag—both cost only pennies.
- An NFC system becomes more expensive when is used for dual-mode technologies, like a smartphone application or credit card communicating with a credit card terminal. Keep in mind that most smartphones today have NFC chips built in, which minimizes cost for those creating an NFC-based system.
- Passive RFID becomes more expensive if you require more high-power readers, which, as previously mentioned, is necessary if you want to use passive RFID for location management.
- Active RFID becomes more expensive based on the types and number of tags, and the number of readers you deploy. Keep in mind that active RFID tags run anywhere from $5 to $15 apiece, and are battery powered.
Asset Location Management Using Active RFID & NFC
At AirFinder, we found that NFC is one way to make a secure connection to an active RFID tag in order to better secure our asset location management system. Therefore, we started manufacturing active RFID tags with NFC readers in them. This allows our customers to scan and provision each tag with their phones, regardless of whether they have bluetooth infrastructure in place where that tagged item is being provisioned.
For example, if you regularly transport eggs and want to monitor location and environmental data associated with the egg crate —like temperature and vibrations—you could essentially use the AirFinder phone application as a replacement for a barcode scanner, and easily add the location data of the crate into your system.
If you’d like more information about RFID vs. NFC, contact us. We’ll help answer any additional questions you may have.