Bluetooth® technology is one of the world’s best known brands and one of the most ubiquitous wireless communications technologies on the planet. It’s been in existence since 2000 and has found its way into billions and billions of devices. Last year alone, over three billion Bluetooth devices were shipped by manufacturers.
Bluetooth has not stood still. Since its first incarnation, Bluetooth has been carefully and systematically improved so that it has continued to keep pace with market requirement, and continued to support and inspire innovation.
Bluetooth mesh networking is the latest chapter in this incredible technology story and 150 companies, all members of the Bluetooth SIG, have helped create it.
This is the first in a series of articles where we’ll introduce you to Bluetooth mesh networking. We start with a two-part overview and will then proceed to explore aspects of the technology in greater detail in subsequent parts of the series.
Flavors and Features
People interested in Bluetooth® technology will be accustomed to seeing new releases adopted by the Bluetooth SIG at regular intervals.
Typically, new releases equip Bluetooth with additional features or they improve upon existing capabilities in some way. Every now and again though, an entirely new “flavor” of Bluetooth is released; a quite distinct variant of Bluetooth, which uses radio in a different way and is optimized in its design and implementation for broad sets of use cases.
Bluetooth Basic Rate/Enhanced Data Rate (BR/EDR) was the first flavor of Bluetooth to be released. It was intended to act as a cable replacement technology and soon came to dominate wireless audio products and be the enabler for new computer peripherals, such as wireless mice and keyboards.
Bluetooth Low Energy (LE) was the next truly distinct Bluetooth technology to appear. It was optimized to use as little energy as possible with devices that incorporate it and able to operate and communicate wirelessly, powered by only a coin-sized battery, which could often last for many years. It’s been very widely adopted. It’s hard to find a smartphone or tablet that doesn’t support Bluetooth LE. Health, sports and fitness devices, like activity trackers, rely on Bluetooth LE technology. So do wearables, like smart watches. The impact of this Bluetooth flavor has been impressive and widespread.
So is Bluetooth mesh networking a new flavor of Bluetooth? Or is it a new feature?
In fact, it’s neither. Let’s find out more about this exciting new Bluetooth technology, how it relates to other forms of Bluetooth, what it can do and how it works.
The Crucial Three
It’s common to find Bluetooth BR/EDR and Bluetooth LE both available in devices like smartphones, but they do not rely on each other’s services and capabilities. To all intents and purposes, those two Bluetooth flavors work independently of each other. In fact, whilst they’re quite happy to coexist in the same device, it’s not possible to use Bluetooth BR/EDR to communicate with a Bluetooth LE device or vice versa. They’re happy in each other’s company, but they don’t talk.
In contrast, Bluetooth mesh networking uses and is dependent upon Bluetooth LE. Bluetooth LE is the wireless communications protocol stack which Bluetooth mesh makes use of.
Bluetooth mesh is not a wireless communications technology. It’s a networking technology.
Figure 1 shows the relationship between Bluetooth BR/EDR, Bluetooth LE and Bluetooth mesh.
Figure 1 – The relationship between Bluetooth mesh and Bluetooth LE
A Tale of Topologies
At its most basic level, Bluetooth BR/EDR lets one device connect to and communicate with another device, establishing a 1:1 relationship which is reflected in the term “pairing”, which most people will be familiar with. Some devices can have multiple 1:1 relationships with other devices and can form a kind of hub / spoke topology known as a “piconet“.
Bluetooth BR/EDR and one-to-one topologies
Bluetooth® LE devices can also form 1:1 and hub/spoke relationships with other devices, as well as work in a connectionless way, broadcasting data which any other device in direct radio range can receive. This is a 1:m topology where m can be a very large number! If devices listening to broadcasts are doing no transmitting of data themselves, then the broadcasting device has the radio spectrum to itself and there’s no effective limit to the number of other devices that can receive and make use of its broadcasts. Bluetooth beacons are an excellent example of this capability in action.