NFC and Bluetooth: The Perfect Pair
It was two decades ago that a new wireless technology called Bluetooth, named after an ancient Danish king, first appeared. It promised to replace the many cables connecting users and their devices to accessories like headsets. Those mature enough may well remember the first time they saw someone passing by speaking into the air with that funny looking gadget hanging on their ear. Since then it has been an incredible march and Bluetooth technology is now almost everywhere.
There’s just one little problem. Unlike real cables, wireless communications share the medium and so the two ends of a cable replacement must be made to know each other before data can flow, unlike the physical cable that you just plug in. The Bluetooth solution is called pairing. It means telling one device to search for other devices to connect to, and after some numbers are input or compared, to connect. The next time the devices get within range of one another, this process happens automatically.
It sounds fairly simple, but the devil’s in the details. It takes time to discover devices. The device names are usually quite technical and it’s difficult to recognize one from another if multiple devices are within range. And that automatic pairing after the first time doesn’t really help if you want to share the headphones with family and friends when it’s always connected to your music player.
This is where NFC comes into play. By the numbers, it’s a modest technology, transmitting only a few hundred kilobits per second and barely reaching farther than a couple of centimeters. However, it provides exactly what is needed: the equivalent of plugging in a cable. The strict proximity that NFC requires means there are exactly two devices you want to connect and you want to connect them now. The amount of data that can be transferred in a second or so is more than sufficient to provide all the technical details they need.
The technical basis for this “tap to connect” process is provided in the NFC Connection Handover specification running atop the NFC Forum protocol stack. It defines a framework of messages and data containers that allow bootstrapping of alternative (i.e., other than NFC) carrier connections in a standardized way. Combined with the information specific to a carrier technology, usually defined by another standardization body, all that is needed to jump into that carrier’s connection process is exchanged with a simple touch. And if that’s not enough, it is even possible to use a smartphone to mediate a connection setup between two other devices in case they can’t be moved.
The combination of Bluetooth and NFC is undoubtedly compelling and its first use appeared in the earliest prototypes of NFC phones. It’s thus not much of a surprise that both the Bluetooth SIG and the NFC Forum came to work together on an implementation guide for developers who want to utilize the combination of Bluetooth and NFC in their applications and devices. This effort led the two organizations in 2011 to publish the Bluetooth Secure Simple Pairing Using NFC application document, which has since been appreciated by many developers.
Time has not stood still. When Bluetooth Smart, a.k.a. Bluetooth Low Energy, appeared in Version 4 of the Bluetooth standard, it was obvious that Bluetooth Smart devices could also benefit from fast and easy pairing, and should be reflected in the application document. It has now been delivered into the hands of developers with the recent publication of Bluetooth Secure Simple Pairing Using NFC version 1.1, available on both the NFC Forum and Bluetooth SIG websites. Like its predecessor, it provides a helpful guide for developers. For consumers, it means many more, exciting products to come.