Bluetooth Low Energy is a protocol optimised for controlling smart lighting. It overcomes the drawbacks of
communication protocols such as ZigBee and Wi-Fi and can be combined with other technologies to make smart
lighting even smarter.
By Saara Guastella, Product Marketing Manager, Casambi
There has been lots of talk about the benefits of smart lighting, not least how it can save energy and make our homes, workplaces, hospitals and other buildings more comfortable. But actual smart lighting implementations remain relatively uncommon, partly because of the wireless technologies that have typically been used.
If smart lighting is to be convenient and intuitive, it must be controlled wirelessly via a mobile device, such as a smartphone, tablet or wearable. The trouble is, the wireless technologies that have been trialled in smart lighting, including Wi-Fi and ZigBee, have drawbacks that hinder adoption and usage of these systems.
For a start, you won't find ZigBee in most phones and tablets, meaning you'll need an additional dongle or gateway between your control device and the lights. As well as increasing the overall system cost, there's the risk involved in having a single gateway to your system: if it fails, you may have no other way in.
Wi-Fi, on the other hand, is found in most mobile kit, but only connects the device to a Wi-Fi router. From there, you need another form of connection, such as ZigBee, to communicate to your lights. Again, this means there is at least one single point of failure.
The other drawback of both Wi-Fi and ZigBee is their susceptibility to interference. Wi-Fi operates on the Direct Sequence Spread Spectrum (DSSS), and doesn't change frequency or hop. Instead, it centres on one channel that's 22 MHz wide. This 83 MHz-wide band has space for 11 overlapping channels, but only three non-overlapping ones. Consequently, you're limited to having three Wi-Fi networks in close proximity. ZigBee, on the other hand, splits the band into 16 channels, meaning for every Wi-Fi channel, you get four overlapping ZigBee ones. ZigBee also uses DSSS, meaning a Wi-Fi network using the same channel as a ZigBee one will likely interfere.
Most ZigBee-controlled lighting systems use a Wi-Fi gateway to talk to your mobile device: getting the two to play nicely can be a real challenge.
Bluetooth Low Energy (BLE, or Bluetooth Smart) is a more recent innovation, created for the Internet of Things. Its first big selling point is that you'll find it in virtually every smartphone and tablet made in recent years ' and it's the only low-power radio technology that can boast this. You can therefore set up and control a BLE smart lighting system directly, using most existing devices (see Figure 2). This makes BLE-controlled systems simpler and more cost-effective to deploy and run. Moreover, you don't need the gateway or dongle that ZigBee- or Wi-Fi-controlled systems require, meaning you remove these single points of failure. BLE is also less prone to interference, because it uses Frequency Hopping Spread Spectrum (FHSS) modulation.
New-generation wireless lighting control systems enable individual nodes to communicate with one another to relay or share messages, driving towards a state of consensus across the network. This means you can create mesh networks that enable nodes to come on- and offline at any time, catching up with the latest system state information from other nodes.
For end customers, this provides a network that self-organises, self-heals and can be controlled from a single point, because all the intelligence is stored in every node. Users only need an internet connection to enable firmware updates or to store data to the cloud.
BLE-control supports smart lighting features that wouldn't be possible with Wi-Fi or ZigBee. Beacon technology is a good example: this detects when a BLE device enters or leaves the area around the beacon. Build a beacon transmitter into a luminaire and you can create proximity-sensitive smart lighting: Automatically activate a pre-set scene when someone enters a room, or create lighting that follows a person as they move through a building, for example.
Fit can work in other ways, too: imagine a light over a shop or museum display, with a beacon built-in. As someone walks up to it, the beacon could trigger the museum's/retailer's app on the visitor's smartphone to show information about the exhibit.
Next-generation lighting control systems now enable you to collect data from sensors in luminaires and send this to the cloud for analysis (see Figure 4). Analyzing this data can yield a range of insights, which can be used to make your smart lighting respond to factors such as ambient light, humidity or CO2 levels. You can also use the data to count people, log events, deliver marketing messaging at the right time or help manage crowds.
BLE has the potential to take smart lighting control to levels that alternative wireless communication technologies have so far been unable to. Because so many people own smartphones, smartwatches and tablets provide built-in BLE, you remove the need for a dedicated gateway to control the lights, thereby reducing complexity and taking out single points of failure. Moreover, BLE offers lighting and system designers exciting opportunities to offer new features, by incorporating additional technologies, such as beacons, into their products.