On a recent Internet of Things Podcast episode, we took a call from our Voicemail hotline segment with a question about Matter over Thread devices. John called in to ask about the range of Thread devices in a smart home.
On one side of his house, he has a second-generation Google Nest Hub that will work as a Thread Border Router. And he has a Matter device that uses Thread one floor down on the other side of his house. John is wondering if and how those two devices will communicate with each other, given their locations and about a dozen walls between them.
When it comes to wireless data transfers, there are many factors involved. John is right to question the range of these devices based on how far apart they are and how many obstructions are between them. Additionally, the type of radio technology is a factor, as are the antennas in each device, how much power is available to the devices for signal amplification and the radio frequency used.
Right off the bat, the Thread protocol uses the IEEE 802.15.4 standard for low-rate transmission. This is actually the same wireless protocol that Zigbee devices uses, so we can get a reasonable range estimate based on Zigbee.
Indeed, we reached out to the Thread Group and a representative there said Thread devices provide roughly the same wireless range as Zigbee devices. The estimate provided to us was up to 50 feet indoors and up to 100 feet outdoors. Keep in mind that those figures represent a “best case” scenario.
Realistically, in a typical home, I’d expect around 25 feet to 30 feet of range between devices. And although we don’t know the size of John’s house, I suspect that his Matter over Thread device won’t reach his Thread Border Router.
However, Thread is a mesh networking technology so the addition of more devices will build up that network over time. I’d recommend spreading Thread devices around the home wherever possible for this reason. Additionally, the Matter standard supports data transmission over both Thread and standard Wi-Fi.
Battery powered devices will tend to use the former, while devices with constant electric power often use the latter. When choosing a Matter device then, if you think it might be out of range of your Thread network, look for one with Wi-Fi, if possible.
To hear John’s question in full, as well as our discussion on the topic, tune in to the Internet of Things podcast below:
The point of a mesh network like thread is that a device that can act as a repeater (generally a mains power device) can therefore pass along a message from another device on the same network so that the workable coverage size of the network is significantly increased.
While it’s true that the probable range of a single “hop” for thread will be around 15 m, last time I looked thread will support up to 16 hops of good quality. That’s similar to Zigbee 3.0, by the way.
So you get a coverage distance of 30 m to the next mains powered thread repeater. And then 30 m to the next, and so on.
The repeaters make up the “backbone“ of the mesh network, with the battery powered devices using that backbone to get messages to the next border router.
Right now, I think the only thread repeater device you can buy is the Eve Energy smart plug:
> As a router node, Eve Energy relays other Thread accessories’ data packets and enhances the stability and reach of your smart home.
So add one of those smart plugs (or any other thread repeater device once more come on the market), and now you’ve added another 15 m or so of range.
Again, this is exactly the same way Zigbee works now.
For that reason, I would have to respectfully disagree with the idea that you need Wi-Fi to get greater range in a matter setup. You can certainly use Wi-Fi devices if they make sense to you for any given location, but you can also use thread devices as long as you have laid out a backbone to cover that range of thread repeater nodes. It’s the mix of batterypowered thread devices and Mains-powered thread devices which will give you a strong physical network to run matter over.
Sorry, I said 30m to the next hop, it’s more likely to be 15m indoors.
That’s very helpful JD. With my routers being the backbone I should be all right. Looking forward to more Matter devices over the year
It’s a shame that 15.4-over-powerline never happened, as it would be an ideal drop-in solution for both Thread and Zigbee.