In recent years, the ‘smart home’ term has become a buzzword. There are more and more devices on the market, that you can control by your smartphone: from light bulbs and switches, to washing and dishwasher machines, and refrigerators too. You can program your lights to turn on when you enter a room, adjust their brightness and color temperature, and you can be notified when your clothes have been washed.
Smart solutions not only let you control them by your smartphone, wherever you are, but when running in an ecosystem, they can simplify certain tasks for you. You can define so-called ‘scenes’ that command selected smart devices to transcend to a specific state. Imagine, for instance, commanding your voice assistant to switch your room to ‘cinematic mode’, which will dim the light, close the shades, and adjust audio volume for you-all by one voice command or a tap of a button. Or, you can optimize your household’s energy consumption by automations that switch off the AC when you open a window or start the washing during off-peak hours. The possibilities are endless.
Smart home is a wide term. You can use it to refer to a flat where you have a couple of devices paired with your smart home hub from Apple, Google, Amazon or others. This is simple and doesn’t require expert skills. You usually scan a code on your new smart appliance using your smartphone, and that’s mostly it. The same ‘smart home’ term, however, may be used to refer to complex systems, whose infrastructure is designed along with the architecture of your new house.
But how does it all work? How do smart devices communicate with each other? What controls their behavior? Well, it’s a broad topic, and I won’t be able to cover all these here, but let’s at least start from something.
I would broadly divide smart systems into two groups: wired and wireless. When I think of wired systems, I picture a large rack full of smart controllers installed on metal rails. All with a bunch of wires connected to them, and hundreds of meters of cables running from there to various home appliances like lights, shades, curtains, doors, electrical outlets, AC controllers, and others. A cable connection is usually the most reliable one, but this approach requires an expert to design, build, configure, and maintain. It’s one to definitely consider when you are planning to build a new house, but does it also make sense when you already have a house or an apartment, and you are not planning a renovation? Well, I think this is the case when you would rather go smart without turning your home upside down.
In this scenario, wireless solutions may perfectly suit your needs without making you utilize a hammer drill to lay a new cable infrastructure. Wireless solutions are usually designed in such a way that they are intuitive to pair with and operate, so they may be relatively easy to apply, even for non-technical users. There are a couple of matters to take into account when considering them, though, like wireless connection stability, battery lifespan (for battery-powered devices), data security, and possible radio signal interference with other devices in range, that may cause connectivity issues. Let’s analyze how the devices communicate and how the connectivity standards they utilize deal with these. Below is a list of selected communication standards from among the most widely-used ones.
The Wi-Fi network protocol is the most widespread one. You use it on a daily basis with your laptop computer or smartphone, and so does a wide range of smart devices. When choosing a wireless smart device, you will probably want it to use Wi-Fi since it will be the easiest to connect to your home network for the start, without the need to buy any extra controller devices that some other communication protocols require. But let’s also consider the possible downsides of this choice.
The range of smart devices is very wide, but when thinking of more complex systems, smart things may be distributed in various locations in your house or apartment, in many cases hidden behind switches in walls or behind furniture. So when you don’t ensure good Wi-Fi signal coverage in these places, you may experience annoying delays or failures to operate the smart devices. A single Wi-Fi internet router at home, which is usually the case, may not necessarily be enough.
Another thing is that most Wi-Fi devices operate on the 2.4 and 5 GHz bands. When multiple Wi-Fi networks are in range, they might cause unstable connectivity, and so may Bluetooth devices for example, because they operate on the 2.4 GHz band. But let’s not exaggerate this too much-the problem doesn’t necessarily apply to your environment.
It’s worth mentioning as well that Wi-Fi devices aren’t usually powered by batteries, since their power consumption is relatively high. There are applications where a battery is the most convenient source of power, though-consider a door/window sensor, for example. The battery or batteries, even with a higher total capacity, would have to be replaced more often compared to other protocols designed specifically for smart devices (not to mention the bulkiness of devices with AA batteries instead of the coin-sized ones).
The Bluetooth Low Energy
The Bluetooth Low Energy (BLE for short) protocol was designed with power consumption in mind. Compared to Classic Bluetooth, it is intended to provide reduced power consumption and cost, at the same time maintaining a similar communication range. It is good for battery-powered devices thanks to its low energy profile (BLE devices will actually sleep most of the time). The batteries, even coin batteries, can last for months or even years (depending on the type of devices and their configuration). A major advantage of this protocol is that it is widespread too-it’s hard to think of a smartphone without Bluetooth support.
Compared to Wi-Fi, however, it has a significantly lower range, and similarly to Wi-Fi, may be prone to interference with other devices that use radio transmission on the widely-used 2.4 GHz band, especially Wi-Fi, but also some wireless phones or microwave ovens. BLE devices may support mesh networking to solve the low range problem, but it’s not something inherent to this protocol, and it doesn’t mean that every smart device will implement mesh networking (as opposed to other protocols you’ll learn about in a moment).
What’s also worth noting is that smart Bluetooth devices will be easy to pair and operate with your smartphone only when you are in proximity, but things may get more complicated when you’ll want to have a central controller for your smart home system for automation and remote control. Assuming that it does or can support Bluetooth communication, you will still need to make sure that your devices can communicate with it from all the places they are located.
If you use smart devices, you probably know ZigBee already. It has a wide range of applications in various smart controllers available on the market, with relatively low prices (compared to devices using other communication protocols). One of the features that makes it suitable for smart device networks is that it natively supports mesh networking. It may be really practical when your devices are distributed in various places in your house, distant from the central controller and without direct visibility between them and the controller.
Another thing is that the protocol is designed for low power consumption, so battery-operated ZigBee devices may live even for several years on a single battery. And the communication is secure-ZigBee uses the AES algorithm with a 128-bit key for data encryption.
ZigBee devices operate on the widely-used 2.4 GHz band globally, however, so they will be more likely to interfere with some other devices around. Nevertheless, the ZigBee PRO 2017 specification adjusts the standard for sub-GHz frequencies (that is below 1 GHz). With this specification, ZigBee becomes a mesh network capable of operating in two frequency bands simultaneously: 800~900 MHz depending on regional regulations, and 2.4 GHz globally.
But what does that mean to you? In simple words, the higher the frequency, the more easily the signal is attenuated by obstacles (walls, for instance) on its way between the transmitter and the receiver. So within the sub-gigahertz band we get better coverage, at the same time with lower power consumption, which is perfect for battery-operated devices. The data rate is lower, though, but in fact, it’s usually of minor importance for smart devices, compared to connection stability, since smart devices usually exchange relatively small amounts of data.
ZigBee doesn’t come without downsides, however, but no protocol is perfect. It’s an open standard, which makes it more convenient and cost-effective to implement for manufacturers, but its openness lead to compatibility fragmentation problems. You may come across devices from different manufacturers that won’t talk to each other.
Nevertheless, the ZigBee Alliance (now rebranded to Connectivity Standards Alliance), which established and maintains the protocol, introduced its new version in 2015 (3.0 specifically). ZigBee 3.0 was built on the existing ZigBee standard, but unifies the market-specific application profiles to allow all devices to be connected in the same network, irrespective of their market designation and function. What’s more, ZigBee 3.0 requires certification, which ensures interoperability of devices from different manufacturers.
To use smart ZigBee devices, you will have to buy a so-called coordinator (gateway) device that will bind your network of smart appliances together, and provide the ability to operate them. So this is an extra requirement-for Wi-Fi devices you need a Wi-Fi access point, and for ZigBee devices you need a coordinator, to give a simple comparison.
Z-Wave is yet another protocol actively used in the smart home industry. Both Z-Wave and ZigBee were introduced around the year 2000, so they have existed and evolved for a while now. What makes Z-Wave great is that mesh networking is its fundamental feature, and that all its consecutive versions are backward compatible! What’s more, it operates on sub-GHz frequency bands between 800~900 MHz (depending on regional regulations). Even though the data rates on these bands are lower, as already mentioned, the range is significantly longer compared to devices operating on the 2.4 GHz bands or higher, which is an important factor for stability of smart device networks.
To get a Z-Wave compliance certificate, a device has to pass technical tests by the Z-Wave Alliance. Even though it has an impact on the market price of the end device, it ensures that it is compatible with the standard, so you don’t have to worry about products from different manufacturers being incompatible with each other.
Z-Wave is perfect for battery-operated devices too, because it was designed with power efficiency in mind. The latest specifications (Z-Wave 700 and above) claim a coin battery lifespan of up to 10 years.
As far as security is concerned, Z-Wave employs the AES algorithm with a 128-bit key for data encryption, similarly to ZigBee. And, similarly to ZigBee, you will need an extra controller (gateway) device to bind your network together.
Thread is yet another communication protocol for smart devices. It is a mesh network protocol, but what makes it stand out from ZigBee and Z-Wave is that it uses the IPv6 protocol for network communication-6LoWPAN specifically. IPv6 over Low-Power Wireless Personal Area Networks, because this is what the abbreviation stands for, is designed for even the smallest, low-power devices, with limited processing capabilities, to let them participate in the Internet of Things.
Thread, similarly to some of the protocols described earlier, is designed with power efficiency in mind, so it is applicable to battery-powered devices. Devices operate on two frequency bands, the same as ZigBee, and the communication is secured by the AES encryption too. Also, compliance certification is required, which ensures compatibility of Thread devices.
Last, but not least, Matter-the one to rule them all. Matter is a relatively new protocol, conceived in late 2019, and currently maintained by the Connectivity Standards Alliance (formerly ZigBee Alliance). The standard was introduced to increase interoperability between different device platforms. The alliance brings on board all the main platforms including Apple HomeKit, Google Home, Amazon Alexa, and Samsung SmartThings. Moreover, it has the tech giants that develop and maintain them as members of the alliance. Their presence raises the chances that the scene in the picture below will not be valid, at least in this case.
Thread allows devices to work offline, without requiring access to the cloud at all times, which not only makes them continue working without an Internet connection (which wasn’t necessarily the case before), but also makes them more secure. And platform providers develop SDKs for device manufacturers to be able to easily integrate their devices with their platforms.
Let’s break down the layers of the protocol to clarify what it is under the hood. Matter devices use the IPv6 protocol, so they are individually addressable in the network, and the data transmission is fulfilled over the TCP and UDP protocols. What grabs attention here is that the devices can use any of several different connectivity standards: Thread, BLE, Wi-Fi, Ethernet, and even cellular communication.
This means that if you already own devices using any of these standards, there is a chance that they will get an upgrade in the future to support Matter. If they won’t, however, there will likely be a workaround. For example, you may be able to connect your existing infrastructure, whatever standard it is based on, with a Matter network, by using a dedicated bridge. It refers to Z-Wave networks as well, since, unfortunately, it is not included in the stack.
The variety of protocols to choose from may make you feel dizzy if you’re starting to think of building a smart infrastructure at home. Wi-Fi will probably always be the one you can start from or that you can resort to when you can’t find a smart device for a specific purpose in the main connectivity standard of your choice. If you’re not thinking of any complex systems, just stick to devices that have the compatibility sticker of the smart platform of your preference, like “Works with Apple HomeKit”, “Works with Google Home”, or similar, and you should be more than satisfied.
If you’re planning a more complex home infrastructure with automations, you will want a robust, reliable network of smart devices. For this scenario, it should be best to use a standard specially designed for smart device infrastructures. You will easily find ZigBee devices on the market, that will cover all or most of your use cases, and that you won’t usually overpay for. This standard is definitely one to consider, even though the coming advent of Matter makes any purchase decisions more difficult now if Matter actually matters for you ;). The thing is that it may be a breakthrough technology that you may want to adhere to in the future, but it is not guaranteed that a non-Matter device bought today will be upgradable to support Matter tomorrow.
It’s worth mentioning here that if you’re a geek, you will find ways to handle a heterogeneous network of smart devices, whatever decisions you make now. One of them is a powerful platform named Home Assistant. It’s an open-source home automation hub that supports a very wide variety of devices and has a multitude of possible integrations. If your current smart platform doesn’t support some of your devices, it’s very likely that Home Assistant will! But it’s a topic for another article. Stay tuned!