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Smart Lighting Jul 22, 2017

Why Bluetooth Low Energy Could be the Key to a Smart Lighting Boom

Bluetooth Low Energy is a protocol optimized 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. 

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.

 

Why ZigBee and Wi-Fi Aren’t Ideal for Smart Lighting
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.


Figure 1. The technologies that have typically been used to create smart lighting systems mean you can’t control the network directly from most mobile devices.

 

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 with 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 that 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.


Figure 2. Most smartphones and tablets have BLE built in, meaning you can control BLE smart lighting networks directly.

 

Bluetooth Low Energy Addresses the Issues

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.

Figure 3 illustrates why a BLE ‘mesh’ network is generally much more reliable than ZigBee or Wi-Fi implementations.

 

Mesh Networks and Beyond

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 online and offline at any time, catching up with the latest system state information from other nodes.


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