Before you buy any smart home gear, you must understand how all your gear talks to each other — this will be a significant factor in what products you ultimately decide to purchase.
Ultimately every device in your smart home will be controlled via your home network, whether that's via your phone connected to WiFi or a cloud-based system talking to a device connected via Ethernet. These connect to child devices via an alternative protocol, e.g., BlueTooth.
Having a solid and reliable home WiFi network is critical to the stability and reliability of your smart home. While this might seem obvious, after all, we've all experienced slow download speeds when trying to work in the backyard or poor picture quality when you're streaming Ted Lasso on the wrong side of the couch. For smart home devices, these kinds of temporarily poor network conditions are the difference between your lights turning on or not, or worse, whether the front door unlocks.
There are a few things to consider when it comes to your home networking:
- Supported Protocols: every few years there is a new wireless protocol, start with 802.11a, and with the most recent being 802.11ax — which has been branded WiFi 6. Most newer devices support at least 802.11n, whereas most routers support all the way back to 802.11a/b/g.
- Frequency: you have probably encountered 2.4ghz vs 5ghz WiFi networks. Older networks are almost exclusively 2.4ghz, while newer ones commonly both frequencies. The 5ghz frequency is significantly faster but it's broadcast distance is far less than 2.4ghz. Most smart home equipment uses 2.4ghz because it's fast enough but reaches further.
- Number of Devices: it's not unusual for your smart home to reach 50-200 devices — many of which will use WiFi — most home networks aren't meant to handle more than 20-30 devices. You mostly get what you pay for here: the modem/router/access point combo that your ISP provides you is likely underpowered both in terms of handling traffic, and WiFi signal strength. I personally use a Ubiquiti UniFi setup with access points and ethernet drops located specifically to enable whole-house smarts. Other devices that I see commonly used are WiFi mesh setups like the Eero 6 and LinkSys Velop.
A Hub is a single device that acts as a single place for many other devices to connect to and connect to each other.
Your smart home will likely feature multiple hub-capable devices, although not every one will be working as a hub at all times.
Often Hubs are used as translators between different protocols (e.g., BlueTooth) and WiFi/Ethernet.
In the case of HomeKit, you will have a singular active HomeKit Hub, which will be one of:
- An AppleTV HD, or 4K
- A HomePod or HomePod Mini
- An iPad
Every AppleTV or HomePod/Mini is a candidate for being your active Home Hub, while you must explicitly opt-in an iPad — which must always be powered on and connected to your home network. The currently active Hub will be chosen pretty much at random.
In addition to this, unless you buy only WiFi, BlueTooth, or Thread compatible devices, you will likely have additional hubs for devices made by specific manufacturers.
How Your Devices Connect
There are five primary ways devices connect to your smart home. There are three layers to the smart home network stack; not all five methods of connecting provide all of three: the transmission layer (Ethernet, WiFi, other radio), the network layer (TCP/IP, BlueTooth, others), and the application layer (where the actual device control is done, this would be, e.g., Apple HomeKit, Google Home).
The most obvious is WiFi. These devices connect directly to your WiFi network and communicate with your Home Hub directly over your local network. These devices have full access to the internet (unless you firewall them off) and are almost always 2.4ghz exclusive, which can make setup a bit of a pain unless you have a dedicated 2.4ghz network. For in-depth details, see our full review of WiFi for smart home networking.
- Easy-ish setup.
- Just like any other networked device
- Uses 2.4ghz which means you can’t go exclusively 5ghz
- Interference can be an issue, particularly given it’s 2.4ghz
- Uses a lot of power, so it’s mostly used for devices that are mains powered
You know Bluetooth. When you think of low-powered networking, you might even think of Bluetooth LE (Low Energy). Many devices support Bluetooth as a handy setup protocol to communicate with your phone/tablet in addition to something else for standard operation. Others have it as a less-than-great fallback.
- Common. Most devices can communicate with each other over it, which makes it useful for setup, as both your phone and the hub can speak bluetooth to coordinate the setup of the device.
- Lower power consumption than WiFi
- Still not great on the power consumption compared to dedicated protocols (see below)
- Really poor range
Zigbee is a mesh protocol standard stewarded by the Zigbee Alliance — a group with over 500 companies participating in it. It's super low-power but has excellent range thanks to its mesh capabilities, and it's technically interoperable between manufacturers.
Zigbee is a singular protocol that covers all three layers (transmission, network, application)
The way that Zigbee achieves this super low-power protocol is by not being TCP/IP. Not using TCP/IP means you need a hub that speaks Zigbee on one side and TCP/IP on the other (either via WiFi or Ethernet). The Zigbee devices connect to the Zigbee Hub, and the Zigbee Hub exposes those to the HomeKit Hub over TCP/IP. Often these are wired, but not always. I prefer wired.
- Very low power
- Good range if you have many devices
- There are good cheap devices
- The spec is loose enough that while you can connect your IKEA Tradfri bulbs to your Philips Hue hub… you don’t get full functionality and you can’t see these non-Hue bulbs in HomeKit, only the actual Hue app (or maybe the IKEA app, not sure, I don’t do this.)
- This also means you frequently end up with multiple hubs that all supposedly speak the same protocol. I have three Zigbee hubs.
- It’s a proprietary standard, you have to be a member of the Zigbee Alliance to use it
Thread is the newcomer to this whole thing, and it has the likes of Apple, Google, and Amazon throwing their weight behind it. Thread is based on Zigbee (uses the same radio frequency), but it uses IPv6 instead of its proprietary network standard and doesn't go into the application layer. It's still a mesh network. Some Zigbee-capable devices can speak Thread without requiring new hardware, which is fantastic.
- Still very low power
- Good range if you have many devices
- Because it doesn’t cover the application layer, it doesn’t have the same compatibility issues as Zigbee, so all thread networking is interoperable.
- Natively supported by Apple HomePod mini, so no additional hub is required
- Still very new, not many things support it or have been updated to support it.
Matter is even newer than Thread, with the initial release slated for later in 2022. Matter is the application layer, and Apple, Google, and Amazon (and many others like IKEA and Philips) have committed to supporting it. It will live alongside HomeKit in the Apple Home app and alongside Google Home on Android devices and be seamlessly integrated (at least in Apple's case ;). Matter compatible devices can work in all the major smart home ecosystems, rather than needing to support them all individually. It can run on top of either Thread or WiFi and uses Bluetooth for device setup. Oddly: no Ethernet.
Matter is also open source but is stewarded by the Connectivity Standard Alliance… which used to be the Zigbee Alliance. You won't find any Matter certified devices, but you should be aware that this is coming, as it's a Big Deal™.
Oh, and it doesn't support cameras yet.
- Finally, smart home intercompatibility. For HomeKit this means access to many more devices, similar to the Google and Alexa ecosystems.
- Supports both Thread and Wi-Fi.
- It’s Open Source.
- It’s not finished yet.
- It doesn’t support cameras, and won’t for its first release.
In addition to these five, these are two others I come across with some frequency:
- Lutron Clear Connect — A proprietary standard used by the Lutron Caseta outlets/switches, and their Selena window blinds product. Amazing, but only for their own stuff.
- ZWave — similar to Zigbee, but until recently not really compatible with HomeKit. There is a recently released HomeKit compatible hub, but it’s expensive and really only worthwhile if you’ve heavily invested in ZWave devices and want to switch ecosystems. There is a massive ZWave device ecosystem however.
Before you buy any smart home gear, it's essential that you understand how all your gear talks to each other — this will be a significant factor in what products you ultimately decide to purchase.
So Which Should I Use?
The ideal answer is to use Matter for everything, but with no devices on the market, the next best solution is: use Thread for everything. Thread is built primarily for Smart Home networking. However, even Thread doesn't have massive adoption yet, which means the realistic answer is a mixture of WiFi, Thread, and Zigbee. And avoid BlueTooth if you can.