Bluetooth Mesh

Bluetooth is a great technology. But the standard is broad and evolving quickly, so things that are clear for insiders may be confusing for others. When we exit the 2016, there will be three fundamental variants of Bluetooth: Classic, Smart and Mesh.

Classic is the one that started it all back in 1990's. It is based on the fundamental technology referred to as BR/EDR (Basic Rate / Enhanced Data Rate). It is a streaming radio, used primarily for audio, although there are many other profiles serving scenarios like file / object exchange and products like computer peripherals. BR/EDR is connection - oriented, forming a star topology with a master device in the middle, capable of being in a connection with up to seven slave devices at the same time. Trust relationship is in pairs (master - slave) and slaves do not see each other and cannot exchange data with anybody but the master.

Smart is based on a fundamentally different technology, called LE (Low Energy). LE was originally developed by Nokia (and several other companies) as Wibree in 2006 and merged into the Bluetooth standard in 2010. In contrast to BR/EDR (streaming), LE is a messaging radio, used to exchange very small amounts of data (messages) using as little energy as possible. Similar to Classic, Smart is connection - oriented, forming a star topology with a central device in the middle and peripherals around it. There is no theoretical limit of the number of active connections a central device can handle at the same time, but existing chipsets max out at 8 or 10. Smart connections can be set up very quickly (single milliseconds) and are very light to maintain - a peripheral device may stay in connection for years and still live on a coin cell. Trust relationship is like in Classic: pairs. Peripherals cannot talk to each other, only to the central device.

Mesh is based on LE too, sharing many features, such as very low power consumption with Smart. But the Mesh topology is fundamentally different. It is a regular network. There are no central / peripheral roles and there are no connections. Instead there are peer nodes, exchanging messages. Mesh nodes can also relay messages to other nodes, to extend the range. Mesh was originally developed as a proprietary technology by Silvair (and several other companies) and is now being merged into the Bluetooth standard.

At Silvair we've already field-proven the mesh technology, applying it to large scale professional lighting networks. The most striking is how well it scales. We're reaching single-hop, node-to-node distances of 1500ft. We are deploying 2000 node networks in commercial spaces. Our data collecting nodes handle several hundreds of messages per second. At the same time low power mesh sensors live for a lifetime on single coin batteries.

Bluetooth is a technology in continuous transition. This is the beauty of it. Ten years ago it was considered just "a marketing spec" by standards that surrender today to its technological excellence and omnipresence.