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Bluetooth low energy wireless technology backgrounder

Bluetooth low energy wireless technology will extend Bluetooth wireless connectivity to compact electronics devices powered by coin cell batteries. This technology backgrounder describes this exciting new technology and its potential applications

 

Introduction to Bluetooth low energy wireless technology

 

Bluetooth low energy wireless technology is an ultra-low power (ULP) 2.4GHz RF technology designed to bring wireless links to products that currently use: proprietary wireless that is unable to communicate with other wireless protocols; wired connections; or have (at present) no wireless communication provision but would benefit from one.

 

Examples include devices such as sensors, PC mice, or sports watches that have to run from low capacity batteries for periods of months or years without recharge or replacement. While there are proprietary solutions available (such as Nordic Semiconductor’s nRF24L series), these are not interoperable with other manufacturers’ transceivers.

 

In addition, proprietary technology is unable to communicate with Bluetooth wireless technology, a standards-based wireless technology embedded into millions of handsets and PCs. A Personal Area Network (PAN) centered on a mobile phone communicating with a range of low battery capacity peripheral devices is illustrative of applications that would or could be targeted by Bluetooth low energy wireless technology.

 

Bluetooth low energy wireless technology will encourage rapid deployment of ULP wireless by providing a technology that is interoperable and able to communicate with handsets and PCs featuring modified Bluetooth wireless technology transceivers (see below). The technology will usher in the next generation of RF communications by opening up many new opportunities for wireless data links that to date have been ruled out on the basis of either power or cost.

 

Bluetooth low energy wireless technology is a ULP wireless solution featuring:

  • Ultra-low peak, average and idle mode power consumption;
  • Ultra-low cost plus small size for accessories and human interface devices (HID);
  • Minimal cost and size addition to handsets and PCs;
  • Global, intuitive and secure multi-vendor interoperability.

 

Specification

 

In June 2010, the Bluetooth Special Interest Group (SIG) announced it had adopted Bluetooth low energy wireless technology as a hallmark feature of the Bluetooth Core Specification Version 4.0 (“Bluetooth v4.0”). The specification details a short-range RF communication technology featuring ultra-low power consumption, a lightweight protocol stack and integration with Bluetooth wireless technology.

 

Bluetooth low energy wireless technology has much in common with Bluetooth Version 2.1 + EDR and Version 3.0 + HS (commonly referred to as “Classic Bluetooth wireless technology”). All three technologies are low cost, short range, interoperable, robust wireless technologies operating in the license-free 2.4GHz Industrial, Scientific and Medical (ISM) RF band.

 

But there is one critical difference: Bluetooth low energy wireless technology was designed from the outset to be a ULP technology whereas Classic Bluetooth technology is a “low power” wireless technology.

 

This difference dictates that the operational characteristics of Bluetooth low energy wireless technology and Classic Bluetooth wireless technology are opposites. Classic Bluetooth wireless technology is a “connection oriented” radio with a fixed connection interval ideal for high activity links like mobile phones communicating with wireless headsets.

 

Among several measures to reduce the power consumption (see below) Bluetooth low energy wireless technology employs a variable connection interval that can be set from a few milliseconds to several seconds depending on the application. In addition, because it features a very rapid connection, Bluetooth low energy wireless technology can normally be in a “not connected” state (saving power) where the two ends of a link are aware of each other, but only link up when necessary and then for as short a time as possible.

 

The “Profiles” part of the technology’s layered architecture – that customize the “stack” for a specific application – will be introduced over the coming months. The current specification defines the layers of Bluetooth low energy architecture, starting with the Physical Layer (PHY) (which transmits bits), Link Layer (LL) (which defines packet structure and control) and Host Controller Interface (HCI). Collectively, these three layers are known as the Bluetooth low energy Link Controller (or “Controller”) (See figure 1.)

Bluetooth low energy layer diagram

Figure 1: The Bluetooth Core Specification Version 4.0 defines the Link Controller and Host part of Bluetooth low energy. Profiles will be ratified over the coming months.

 

...to continue reading this technology backgrounder, please download the PDF.

 

The complete document is 3,800 words and includes sections on: Introduction to Bluetooth low energy wireless technology; Specification; Characteristics; Applications; Comparison with Bluetooth wireless technology, and Availability.

 

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