ULP Wireless Update

What’s in a name?

What’s in a name?

Consumers don’t care, and engineers can get confused about what a device ‘complying with Bluetooth 5’ actually is

Be it Classic Bluetooth, Bluetooth v4.0 or Bluetooth low energy, Bluetooth’s various guises aren’t always obvious from the name

Over a decade ago, an enterprising group of technology companies, encouraged and led by Nokia, and including Nordic Semiconductor, spotted a market opportunity for an ultra low power (ULP) wireless technology that could run for months from batteries as modest as CR2032 3V coin cells.

 

Nokia’s vision was for a range of ULP wirelessly-connected accessories sending information to the company’s handsets via a Personal Area Network (PAN). Nokia dubbed its innovation “Wibree”.

 

At the time, Nordic was the leader in proprietary 2.4GHz ULP technology and its chips were commonly found in products as diverse as sportswatches, heart rate monitors, and wireless desktops. However, the company appreciated that an open standard for ULP wireless would dramatically extend the reach of ULP RF technology and was willing to share its hard-won technical expertise.

 

Meanwhile, The Bluetooth Special Interest Group (SIG), promoters and custodians of the Bluetooth Core Specification, the standard that governs Bluetooth wireless, shared a similar vision. The SIG’s popular short-range 2.4 GHz technology had proved successful linking headsets to handsets but was struggling to expand into other sectors. Bluetooth technology offered good bandwidth and range, but, as a ‘connection-oriented’ technology consumed far more power than Nordic’s proprietary asynchronous ULP wireless.

 

Both groups quickly appreciated that Bluetooth’s advantage of adoption by handset manufacturers (who were hardly keen to add yet another radio chip to their products) complemented the Wibree Alliance’s low power consumption technology. And so, in a merger between the Nokia-led grouping and the Bluetooth SIG, “ultra low power Bluetooth” was born. The prototype technology was not yet interoperable with “Bluetooth 3.0”, the latest version of the SIG’s original product which itself had recently been upgraded to a bandwidth of 24 Mbps.

 

Ultra low power Bluetooth was soon renamed “Bluetooth low energy” to better describe its ability to extend battery life. (The Bluetooth SIG insists that the technology is always written as Bluetooth low energy (lower case ‘l’ and ‘e’) and there is no abbreviated form - although many silicon vendors and technical journalists commonly refer to it as “Bluetooth Low Energy”, “Bluetooth LE” and “BLE”.)

 

A hallmark element

Bluetooth 4.0 was adopted in June 2010, with Bluetooth low energy described as “a hallmark element of the [new] Core Specification”. The revised specification described two types of Bluetooth chip: “single mode” (Bluetooth low energy, only interoperable with other Bluetooth devices complying with version 4.0 and later); and “dual mode” (conventional or so-called Classic Bluetooth chips that retained the functionality of Bluetooth 3.0 BR/EDR devices and retrospective interoperability, but also included Bluetooth low energy interoperability to enable communication with single-mode devices).

The Bluetooth SIG later dropped the single-mode and dual-mode description, rebranding single-mode devices as “Bluetooth Smart” and dual-mode chips as “Bluetooth Smart Ready”. Today, those references have also largely been deprecated (although remain prevalent in many chip manufacturers’ datasheets).

 

Meanwhile, the Core Specification itself underwent several name changes. Bluetooth version (or “v”) 4.0 and the subsequent v4.1 and v4.2 updates are now referred to as “Bluetooth 4.0”, “4.1” and “4.2” respectively (i.e. without the ‘v’) and the latest version is known simply as “Bluetooth 5” (rather than the “Bluetooth 5.0” which might have been expected based on the traditional naming scheme). It’s not clear if the next interim update will be called “Bluetooth 5.1” or the SIG will simply opt for “Bluetooth 6”.

 

For the consumer, a single name for the technology—that doesn’t discriminate between the two chips that make up the Bluetooth ecosystem—makes sense. Consumers are just interested in a technology that works and not what’s under the hood. But for engineers today it’s not always immediately obvious whether a device described as “complying with Bluetooth 5” is a Bluetooth low energy chip designed to run from modest power sources, or a fully- functional Bluetooth 5 device typically found in smartphones and tablets. For its part, Nordic specializes in the low energy form of the technology and the company keeps things unambiguous by referring to its chips as Bluetooth low energy devices compatible with Bluetooth 4.0 (and later versions).