Radio frequency identification (RFID) is becoming commonplace in everyday life these days. From tap-and-go payment cards and transit passes to E-ZPass devices used on toll roads to the tags stuck on and sewn into consumer goods to manage inventory and deter theft, most of us encounter RFID tags at least a few times a week and never think about
what can be done with this technology.
In the past few years, a new term has started to bubble up in connection with RFID: near field communication (NFC).Though NFC readers can read from and write to some RFID tags, NFC has more capabilities than RFID, and enables a greater range of uses. You can think of NFC as an extension of RFID, building on a few of the many RFID standards to create a wider data exchange platform.
Imagine you’re sitting on your porch at night. You turn on the porch light, and you can see your neighbor as he passes close to your house because the light reflects off him back to your eyes. That’s passive RFID. The radio signal from a passive RFID reader reaches a tag, the tag absorbs the energy and “reflects” back its identity.
Now imagine you turn on your porch light, and your neighbor in his home sees it and flicks on his porch light so that you can see him waving hello from his porch. That’s active RFID. It can carry a longer range, because the receiver has its own power source, and can therefore generate its own radio signal rather than relying on the energy it absorbs from the sender.
RFID is a lot like those two porches. You and your neighbor know each other’s faces, but you don’t really learn a lot about each other that way. You don’t exchange any meaningful messages. RFID is not a communications technology; rather, it’s designed for identification. RFID tags can hold a small amount of data, and you can read and write
to them from RFID readers, but the amount of data we’re talking about is trivial, a thousand bytes or less.
Now imagine another neighbor passes close, and when you see her, you invite her on to the porch for a chat. She accepts your invitation, and you sit together, exchange pleasantries about your lives, and develop more of a relationship. You talk with each other and you listen to each other for a few minutes. That’s NFC.
NFC is designed to build on RFID by enabling more complex exchanges between participants. You can still read passive RFID tags with an NFC reader, and you can write to their limited amount of memory. NFC also allows you to write data to certain types of RFID tags using a standard format, independent of tag type. You can also communicate with other NFC devices in a two-way, or duplex, exchange. NFC devices can exchange information about each other’s capabilities, swap records, and initiate longer term communications through other means. For example, you might tap your NFC-enabled phone to an NFC-enabled stereo so that they can identify each other, learn that they both have WiFi capability, and exchange credentials for communication over WiFi. After that, the phone will start to stream audio over WiFi to the stereo. Why doesn’t the phone stream its audio over the NFC connection? Two reasons: first, the NFC connection is intentionally short range, generally 10cm or less. That allows it to be low-power, and to avoid interference with other radios built into devices using it. Second, it’s relatively low-speed compared to WiFi, Bluetooth, and other communications protocols. NFC is not designed to manage extended high-speed communications. It’s for short messages, exchanging credentials, and initiating relationships. Think back to the front porch for a moment. NFC is the exchange you have to open the conversation. If you want to talk at length, you invite your neighbor inside for tea. That’s WiFi, Bluetooth, and other extended communications protocols.
What’s exciting about NFC is that it allows for some sophisticated introductions and short instructions without the hassle of exchanging passwords, pairing, and all the other more complicated steps that come with those other protocols. That means that when you and your friend want to exchange address information from your phone to his, you can just tap your phones together. When you want to pay with your Google Wallet, you can just tap as you would an RFID-enabled credit card.
When you’re using NFC, your device doesn’t give the other device to which it’s speaking access to its whole memory—it just gives it the basics needed for exchange. You control what it can send and what it can’t, and to whom.