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Bluetooth SIG takes it down a notch

Low power for high health

The Bluetooth Special Interest Group has approved a low-power variant of the wireless standard, taking on Zigbee and Z-Wave and targeting heath care applications.

Bluetooth Low Energy, as the new standard is unimaginatively named, is what became of WiBree - Nokia's short-lived attempt to create its own low-power standard, which got folded into Bluetooth when it became clear no-one was going to adopt it. The SIG has been refining the standard and now it's emerged as Bluetooth Low Power, with aspirations of connecting button-cell devices and perhaps finally replacing infrared in the TV's remote control.

Like WiBree Bluetooth Low Energy operates in the licence-free 2.4GHz band, but WiBree shared little more than that frequency with the existing Blueooth standard. Low Energy draws much more from it's bigger parent, including frequency hopping and encryption as well as a burst data speed of 1MB/sec.

Not that Low Energy devices are expected to need that kind of speed - WiBree owes its conception to heart-rate-monitoring watches that Nokia wanted to connect to its mobile phones, along with in-shoe sensors for those who want to tweet their jogging progress. That ancestry shows in Bluetooth Low Energy which is expected to find useful applications in health monitoring - or "the wellness industry" as it prefers to be known.

That means lots of time on standby consuming very little power, with a 3ms connection time when data transfer is required and a star topography that removes the seven-device limitation inherent in the Bluetooth standard. Competing technologies Z-Wave and Zigbee, which offer equally slow speeds with even more meagre energy requirements, use mesh topologies to provide connectivity without infrastructure. Full sized Bluetooth has a "scatternet" topology that can create a mesh, but we've never seen it used outside a lab, and the SIG reckons that with such a fast connection time a mesh-like infrastructure can be created without being bound into the standard.

That would depend on having lots of Bluetooth Low Energy devices - the Bluetooth SIG reckons that adding the Low Energy standard to existing devices will have a tiny incremental cost. It envisions that most devices won't bother with the whole Bluetooth stack, which would find little use in a light switch or pair of running shoes. Such devices should be able to run effectively from a single button battery, though we'll have to wait for some implementations before we talk numbers.

Right now, the standard is just a set of specifications, but it's going to need an easily-recogonised logo too as it adds another level of complexity to a standard that's currently just within the public's ability to grasp. With Bluetooth High Speed, Bluetooth Low Energy and plain old Bluetooth to contend with the technically-illiterate might start to struggle, and that's before the forthcoming integration of ultrawide band. ®

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