Bluetooth Low Energy now supports mesh networking
Written by: Sam Fenwick | Published:

The Bluetooth Special Interest Group (SIG) announced today (18 July) that Bluetooth Low Energy (BLE) now supports mesh networking, enabling many-to-many device communications

It is optimised for large-scale device networks that occupy buildings or groups of buildings (e.g. university campuses) and is not being positioned as a technology for smart cities.

It will provide users with multi-path delivery with no single point of failure (enabled without any need for user intervention/set-up), reducing some of the issues associated with using licence-exempt technologies for business-critical processes. In addition, BLE uses multiple frequencies within the 2.4 GHz band, reducing the extent at which BLE networks can suffer from interference from other devices and giving BLE mesh networks greater scalability.

Martin Woolley, technical program manager at Bluetooth SIG, told Land Mobile that commercial lighting is likely to be one of the first use cases for the technology and that most smartphones on the market can interact with BLE mesh networks using software applications. BLE mesh networks have a latency of roughly 100 milliseconds for a six-hop journey, though it can be as low as 50 milliseconds.

He adds that the protocol has been designed to be immune from both “replay” and “trash-can” attacks, using mathematical and encryption techniques to allow networks to identify and reject pre-recorded signals and by changing all the security keys in use across a network when a device is removed from it. Different security keys govern the applications available to each node and the ability for devices to join the network, with full separation between the two. They can also be used to divide a network up into subnets – for example, a network governing the lighting in a hotel, could be divided up so that the nodes within a hotel room are partitioned cryptographically.

Woolley explains that “heartbeat” messages are sent at the network layer, which inform other devices that the device sending it is present on the network, while also informing devices about its location within the network. “They can then use that to optimise communication with that device in the future. So, the network is able to learn about itself, its topology and the distance between nodes.”

The technology uses a “friendship” system to reduce sensor power consumption – this pairs battery-powered sensors with a typically grid-powered device, which stores incoming messages for the sensors and relays them only on the rare occasions that the sensors switch their receivers on, allowing their parameters to be changed wirelessly, while keeping duty cycles low. There’s also extensive use of caching to reduce unnecessary transmissions, and “it sits on top of Bluetooth Low Energy, which is a pretty good start.”

“Within the building automation market, there is a growing focus on connected lighting and the role it can play as a platform for providing automation services throughout a facility,” said Szymon Slupik, president and CTO of Silvair and chairman of the mesh working group within the Bluetooth SIG. “A smart lighting platform built on top of Bluetooth mesh networking can also support asset tracking, point of interest, and way-finding services. These value-added capabilities are part of why we believe Bluetooth is an ideal technology for enabling a mesh network.”

The Bluetooth SIG also claims that by selecting Bluetooth technology, developers can deliver richer solutions with a faster time to market, as they can benefit from:

  • A full-stack approach that defines the low-level radio up to the high-level application layer, ensuring all aspects of the technology are fully specified
  • Comprehensive, multi-vendor interoperability testing, which is conducted during the specification development process – not after specification release
  • A 20-year history of delivering the qualification tools and processes needed to ensure global, multi-vendor interoperability

Bluetooth mesh networking specifications, as well as the tools required to qualify Bluetooth products with mesh networking support, are now available at the Bluetooth website.

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