A year after unveiling Bluetooth 5, the short-range wireless networking technology’s Special Interest Group (SIG) has announced support for mesh networking. This enables low-power, many-to-many device communications and promises to enhance use cases such as smart homes, offices and cities, and industrial IoT applications.
The impetus behind Bluetooth 5 — first supported on Samsung’s recent Galaxy S8 smartphone — was increased speed and range over existing Bluetooth 4.2 LE: it delivers twice the speed (up to 2Mbps), four times the range (enabling ‘whole-home, building, or location coverage’), and eight times the message-broadcasting capability (by using larger data packets). The IoT is a particular focus for Bluetooth 5, especially in regard to beacons — Bluetooth transmitters that can send data to any other within-range Bluetooth devices.
The new mesh capability is built on Bluetooth LE, and is designed for IoT applications where potentially thousands of devices need to reliably and securely communicate with one another.
“By adding support for mesh networking, the Bluetooth member community is continuing a long history of focused innovation to help new, up-and-coming markets flourish,” said Mark Powell, executive director for Bluetooth SIG in a statement. “In the same way the connected device market experienced rapid growth after the introduction of Bluetooth Low Energy, we believe Bluetooth mesh networking can play a vital role in helping early stage markets, such as building automation and wireless sensor networks, experience more rapid growth.”
A mesh networking topology will allow Bluetooth networks to expand their range simply by adding and securely provisioning new nodes, which can have multiple constituent elements. Devices relay messages so that the end-to-end communication range extends far beyond the radio range of individual nodes.
In an industrial site, for example, this means that machine status across the entire plant can be monitored through the mesh, with no single point of failure, and assets can be tracked as they pass through a manufacturing process.
The Bluetooth SIG defines three kinds of addresses for messages sent across the mesh: unicast addresses identify a single device element; group addresses represent one or more elements, and can be fixed or assigned dynamically by users (defining a room in a building, for example); and virtual addresses can be assigned to one or more elements, spanning one or more nodes. The latter are expected to be preconfigured, and could, for example, identify all meeting room projectors made by a particular manufacturer.
As well as sending and receiving messages, node elements can have states (a light being on or off, for example) and properties (a temperature, for example) — the latter can be read-only or allow read/write access. Models define all or part of an element’s relation to the mesh network and come in server, client or control variants, while scenes allow sets of previously stored node states to be recalled on demand — the temperature and lighting in your living room in the evening, for example.
Security is a huge concern for IoT applications, and in a Bluetooth mesh network it is mandatory, with (among other things) all messages encrypted and authenticated, and network, application, and device security addressed independently.
Finally, Bluetooth mesh networking uses a technique called ‘managed flooding’ to broadcast messages rather than route them directly to one or more specific nodes, making for a highly reliable and efficient network.
Bluetooth is not the only IoT mesh networking game in town, of course. For example, in June this year the Zigbee Alliance introduced Zigbee PRO 2017, a multi-band mesh network aimed at large-scale IoT deployments.