Bluetooth 5: Mesh Networking

Understanding Mesh Networking

Bluetooth is a star-type topology (Figure 1a) in which all devices are connected to a central hub. As the devices cannot themselves act as hubs, the only way to extend the network is to connect more devices to the central hub. While this can be accomplished in a wired network (although requiring lots of cable), the range of a wireless star-type network is limited, so its maximum distance is determined by the furthest connected device. A much better solution is the mesh network (Figure 1b) in which all devices communicate with each other, which makes the size and area covered by the network almost unlimited.

Figure 1: The star topology (a) has limited extensibility while the mesh type (b) is virtually unlimited.

The Role of Range, Speed, and Coexistence

Increased range is desirable in any communication application, but it’s particularly important in home automation environments. Bluetooth 5 can now support this application, thanks to its greater range and mesh networking capability. Together, they allow Blueooth-5-enabled devices to be connected throughout a residence of any size and even outdoors and between buildings. As this wasn’t possible before, competing technologies like Wi-Fi and Zigbee began to take advantage of this shortcoming.

Beacons Defined

At a basic level, beaconing is a way to deliver very short messages to and track Bluetooth-enabled devices over a short distance, without the need for pairing between the beacon and the device. The only requirement is that the device, typically an Apple or Android smartphone or tablet, has an installed app dedicated to beaconing. The retail industry is currently the primary user of beaconing, so let’s use this is an application example.

Figure 2: A typical retail scenario for beacons shows how they can be placed inconspicuously anywhere, tracking where shoppers go.
Figure 3: The beacon transmits to the app on the smartphone. If the user takes action, this is sent to the server, which provides additional information by sending the user to a website.

Faster Data Transfer

Bluetooth 5 increases its maximum data rate from 1Mb/s in Bluetooth 4.0 to 2Mb/s. While not a massive increase, it will still allow more data to be communicated in a shorter time. One of the greatest benefactors of this increase is likely to be IoT applications that require near-instantaneous round-trip communications, such as controlling robotic surgical devices in medicine and machines on a production floor. It can also let an IoT device store data for days and send it all at once in seconds rather than periodically in pieces. This will reduce power consumption in IoT devices, which is essential for long battery life.

Ability to Coexist

In addition to the benefits we’ve discussed, Bluetooth 5 has other enhancements that will increase its already formidable capabilities, one of the most important of which is its ability to coexist with other services in the 2.4 GHz Industrial Scientific and Medical (ISM) band.

Simplifying the Solution

While many systems will use a single connectivity solution, others will use several. From a designer’s perspective, this would require a separate SoC for each one, driving up costs and complexity, and probably increasing time to market. It didn’t take long for silicon vendors to address this, and an increasing number of SoCs accommodate multiple protocols.

Figure 4: The development kit for the Nordic Semiconductor nRF52840 SoC is a single-board solution that speeds the design of products using Bluetooth 5, IEEE 802.15.4m, and proprietary connectivity standards.
Figure 5: Skyworks’ SKY66112–11 front-end module is compatible with Bluetooth 5.

Conclusion

The features of Bluetooth 5 described in this article are the major ones but there are many more “tweaks” to the standard contained within each one, along with other features that collectively make the low energy version of Bluetooth equal to or better than its competitors for IoT applications. Mesh networking is the most broadly useful as it makes the standard more than a short-range personal area network for the first time. However, its greater range, improved beacon support, higher data rate, and greater message length and dozens of other enhancements combined with frugal use of power, low implementation cost, and massive market penetration, ensure it will continue to be a highly competitive connectivity solution for years to come.

--

--

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store