How to manage wireless sensor networks with dual-band connectivity


One recent trend for Internet of Things (IoT) applications (especially in building automation) is that while “smartness” is being added to things, more objects are connected and the complexity of provisioning and maintaining such a system increases becoming a challenge for the adopters.

As such, simplifying and reducing the cost of deployment and maintenance of the sensor network is one of the key requirements for the players in the Industrial market. When using Sub-1 GHz as a connectivity link, the performance of the system greatly benefits from the underlying technology, due to a less crowded spectrum than 2.4 GHz, longer outdoor range and better indoor performance. Today, there are system-level solutions to easily build Sub-1 GHz to IP wireless sensor networks that can address building, factory and retail automation needs, where coverage of the whole area is realized with a star-network topology,.

However, large network deployment and maintenance also requires that each and every single node of the network is accessible and can be operated independently. One of the biggest challenges to perform these tasks is that in most cases sensors don't have a display to interact with or relay this information locally to the technician sent on site to commission or repair a device in the network. Take the example of a lighting technician, sent regularly to several buildings to check on the Sub-1 GHz fixtures and ballasts which are hard to reach to manually set into ‘maintenance’ mode with a special button press.

What if he could use a direct Bluetooth® low energy link with a tablet or a smartphone as the backup display, to capture the information that the ballast sent 'intelligently' (e.g. only when in the proximity of the device), or when he wants to trigger a diagnostic operation on that node?

Or, what if a professional home security installer could use the direct Bluetooth low energy link with a tablet to add a set of Sub-1 GHz door and window sensors to an existing security network? He could avoid Sub-1 GHz in-band commissioning procedures (which require the gateway to be involved while at the same time operating in the network). Network parameters and security materials (like keys and certificates) could be exchanged on the 2.4 GHz band as well, in a safer and more reliable way than using the native Sub-1 GHz band.

The alternate Bluetooth low energy link could also be employed as a higher throughput backup channel. Firmware upgrades can be pushed faster, saving overall power and without disrupting the rest of the network while the firmware is upgraded on the node.

By adding the ability to smoothly interact with a smartphone, DYI users, technicians and professional installers can more securely and easily create, install and maintain a network of Sub-1 GHz wireless connected devices (e.g. like an alarm or security system in a home, a pressure/flow sensor network in a factory, or the elevator cars in a building).

With products able to support dual-band Sub-1 GHz and 2.4 GHz Bluetooth low energy connectivity, benefits of the respective technologies can be leveraged within their class of merit: long range and robustness to interference when using the Sub-1 GHz link, and easy smart devices ecosystem integration when using Bluetooth low energy.