Here’s what you need to know about smarthome protocols

Here’s what you need to know about smarthome protocols

A smart home can be useful, but if you’re buying a few smart products from different brands, you need to make sure they all work together. This is done with protocols: agreements to communicate with each other. There are several smarthome protocols of all types. How do they relate to each other? And what should you pay attention to if you want all your smart devices to communicate with each other?

Smart products can only be smart through communication with other products. A lamp that is just a lamp and that you cannot switch on or off remotely is not smart. You should at least be able to control it remotely, and preferably also with an app. And you can only really speak of a smart lamp if you can control them via a smart home controller. Then you can, for example, switch the lamp on and off automatically based on the presence of people, the time or sunset.

01 Layered Protocols

This communication with smart products takes place via a protocol. That is essentially a standard that lays down all kinds of agreements about what exchanged messages look like. In principle, all products that adhere to the same protocol can communicate with each other. But one protocol is not the other.

We can distinguish different types of protocols, and you can present them in layers. The top layer is closest to us, the user. The bottom layer is closest to the devices. And some protocols are in intermediate layers to translate between protocols above and below. Moreover, many protocols themselves consist of sub-protocols, each of which is also contained in its own intermediate layer.

02 Top layer and bottom layer

You can roughly divide the smarthome protocols into two layers. At the top you have the protocols that you come into contact with as an end user. These are, for example, Google Assistant, Amazon Alexa or Apple HomeKit. These ensure that you can control supported devices via an app or voice. But also smarthome controllers from the DIY world, such as Home Assistant or Domoticz, provide an API and web interface or app that allows you to interact with devices regardless of the underlying technology.

At the bottom, you have protocols that use a specific medium to allow devices to communicate with each other. This often involves wireless protocols, such as Zigbee or Z-Wave. Thread, which is becoming more and more established, is also in this list. And of course you also have smarthome protocols that work in the house via cabling, such as KNX.

03 Four Layers of the Internet Protocol Suite

Smart home protocols are often divided into four layers by analogy with the Internet protocol suite (TCP/IP). At the bottom is the connection layer, which describes the physical medium. Wifi (802.11), IEEE 802.15.4 and Ethernet are located in this layer. Above this is the network layer, which enables communication across network boundaries. For example, here you will find the IP protocol.

The transport layer above this ensures that data is delivered correctly. Think of UDP and TCP. Finally, the application layer, at the very top, allows applications on the same or different devices to communicate with each other. Http is located in this layer. But also the smarthome protocols that you come into contact with as an end user.

04 Multi-layer protocols

The internet protocol suite has nicely separated layers. We can therefore usually clearly indicate which layer of internet protocols they are in. But many smarthome protocols are not built for the Internet, and are therefore multi-layered. Let’s take a look at some of them.

Z-Wave is a protocol in which all four layers are closely aligned. In practice they are therefore regarded as a whole. With Zigbee, on the other hand, the layers are clearer. Zigbee is in the network layer, transport layer and application layer.

The latter is called Zigbee Cluster Library (ZCL) in this protocol, and a more universal version of it that you can also use over other protocols is Dotdot. For the connection layer, Zigbee uses IEEE 802.15.4, a wireless mesh network that operates at a frequency of 2.4 GHz.

05 IP based

A new IP-based smart home protocol is Thread. Like Zigbee, Thread builds on IEEE 802.15.4 for its connection layer. Thread itself resides in the network layer and transport layer and thus has no application layer. In fact, Thread is not strictly speaking a smarthome protocol, but merely a protocol for reliably transporting data over a wireless mesh network.

Interesting about Thread is that the network layer consists of 6LoWPAN. This standard makes it possible to run an IPv6 network over the connection layer 802.15.4. The transport layer contains udp, which we already know from the internet protocol suite. As a result, each Thread device has an IPv6 address and can communicate directly with normal IPv6 devices that way. je home network (with ethernet and/or wifi) is connected to your Thread network via a border router, and that simply forwards data packets in the network layer.

06 HomeKit about Thread

Above Thread you can therefore run all kinds of application protocols for smart homes. One such protocol is Apple’s HomeKit. For example, the HomePod mini is not only a Thread border router, but also a hub with which you can control your HomeKit-compatible devices. Manufacturer Eve, among others, has a lot of devices that support HomeKit over Thread.

It makes no difference to HomeKit whether your smart devices are connected via WiFi, Bluetooth or Thread. You can address them all in the same way through the HomeKit platform. You can do that through you iPhone, iPad or Apple Watch and you can also control your devices with Siri. The only thing to keep in mind is that the device displays the HomeKit support logo.

06 The HomePod mini is both a Thread border router and a hub.

07 Matter

A newer application layer is Matter, which was initially known as Connected Home over IP. As the previous name implies, the Internet Protocol is central to this. So in principle Matter runs above every IP stack. For now, Thread, Wi-Fi and Ethernet are supported, and Matter over a cellular network is also coming.

Matter was started by the Zigbee Alliance, the organization behind the standardization of Zigbee. The application layer is therefore strongly inspired by that of Zigbee. Due to the new focus, the Zigbee Alliance has meanwhile changed its name to Connectivity Standards Alliance.

The first Matter devices should hit the market this year. Many big names in the smart home world are behind the standard: not only Amazon, Apple and Google, but also Signify (from Philips Hue), IKEA, Samsung (from SmartThings) and Tuya. Because Matter devices are IP-based, it is easier for manufacturers to make them compatible with smart home systems and voice assistants such as Apple HomeKit, Amazon Alexa and Google Assistant.

Online or offline?

Many smarthome protocols work locally, such as Zigbee, Z-Wave, Thread, and even Matter. That means you can still control all your devices if your internet goes down. After all, your local smarthome controller doesn’t need internet. A Philips Hue bridge can also be controlled completely locally with an API.

This is different with the voice assistants such as Apple Siri, Amazon Alexa and Google Assistant: they work via the cloud and have few or no options offline. Since iOS 15 you can do a lot of things offline with Siri, and Google Assistant also has limited offline support.

If you opt for a smarthome platform that uses the cloud, then you also depend on the good will of the manufacturer. For example, in 2020 Wink decided to make his free cloud service paying. Users who refused to pay (after all, they were lured with the promise that the service would always be free) were no longer able to access their Wink devices.

08 Link protocols

You will rarely have all devices with the same protocol at home. After all, the market is evolving, and so are your requirements. Maybe you started out with Z-Wave devices, added Philips Hue lights and other Zigbee devices, and now you’ve set your sights on Thread. That doesn’t have to be a problem, because with the right hardware you can connect multiple protocols.

With IP-based protocols such as Thread and the parent Matter, this link is simple: thanks to the border router, each device can be accessed via its IP address. Protocols that are not based on IP, such as Zigbee and Z-Wave, require a translation step to connect the devices to your home network and to be able to access them via your smartphone, for example.

09 Bridge

The device that takes care of that translation is called a bridge, gateway, hub or controller. An example is the Philips Hue bridge. On the one hand, it contains a Zigbee chip that communicates with the Hue lamps (and other lamps that support the Zigbee Light Link standard), and on the other hand an Ethernet cable that you connect to your home network.

You can then control your lamps with the Philips Hue app on your smartphone. The app communicates via your home network with the Hue bridge, which translates the commands into the correct Zigbee messages.

The bridge also contains a web server with a REST API: with this you can control your Hue lamps via the bridge with other home automation controllers, such as Home Assistant. Finally, the Hue bridge also supports Apple HomeKit. You can also control all your lights by asking Siri on one of your Apple devices.

09 The Philips Hue bridge is an example of a device that provides a translation.

10 Controller for all protocols

You can have your own bridge for each protocol, but soon you will have several boxes in your house that all consume power and which you all have to connect to your network. If you use multiple smarthome protocols in your home, it is often more interesting to use an integrated controller that supports them all.

An example of such a controller is the Homey Pro. This spherical device supports WiFi, Bluetooth low-energy, Zigbee, Z-Wave Plus, infrared and radio signals at 433MHz and 868MHz. In the web interface and the accompanying mobile app you can control and automate all these devices in a uniform way.

10 The Homey Pro is a smarthome controller that speaks all kinds of smarthome protocols.

11 DIY controller

You can also build such an integrated controller yourself. For example, you take a Raspberry Pi and connect transceivers for Zigbee, Z-Wave, 433 MHz and so on. As software you then run an open source platform on it, such as Home Assistant, Domoticz or openHAB. Just like with Homey, you can control all your devices here in a uniform manner, independent of the underlying protocol.

You can also support some of the protocols in your DIY controller and some externally. For example, you can control the Philips Hue bridge from Home Assistant via the local API. The open source smart home platforms can usually also work completely without internet, but if you want you can also integrate cloud services. For example, Home Assistant supports integration with Google Assistant and Amazon Alexa.

11 In Home Assistant you can easily add support for all kinds of smart home protocols.


It is not always easy to add support for a new protocol to existing smart devices. Inform yourself well with the manufacturers. For example, in 2020 Eve has provided support for Thread on some of its Bluetooth low-energy devices for HomeKit thanks to a firmware upgrade. This was possible because both bluetooth low-energy and Thread work on the same frequency and were supported by the chip used.

Similarly, many Zigbee devices can be converted to Thread with a firmware upgrade. In addition, Eve promises that its Thread-based HomeKit devices will also receive support for Matter via a firmware upgrade. Signify takes a different approach: it promises support for Matter, but only in the Philips Hue bridge. It will still communicate with the individual lamps and switches via Zigbee, so that you cannot take full advantage of the benefits of Matter.


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