Wi-Fi's history with IoT has been rocky, but are the new updates from Wi-Fi 6 enough to make it a viable option for IoT connectivity?
In September of last year the Wi-Fi Alliance finally launched its certification process for Wi-Fi 6, marking the finalization and launch of the Wi-Fi 6 (802.11ax) standard. Wi-Fi 6 comes with a whole host of upgraded features, including better management of crowded networks, and the ability to talk in the newly available 6 GHz frequency.
With all of these changes, it's worth asking the question “can Wi-Fi be used for IoT, and if so why couldn’t it before?”
It all comes down to two things: power consumption and bandwidth. Wi-Fi is generally known as a bit of a power hog, and in the past could be expected to use an order of magnitude more energy over a given time period for a device than comparable LPWANs (Lora, NB-IoT, SigFox, etc).
This is generally because Wi-Fi required periodic messages to let the router know a device was still connected or it would have to renegotiate its connection, which takes even more time and energy to accomplish. Bandwidth is something one might expect Wi-Fi to shine with, given that it's capable of speeds in the 1 Gb/s range.
However, as the number of devices on a Wi-Fi network grow, the speeds slow down significantly. This is because Wi-Fi is only capable of talking to 4 or so devices on the network at a given time. Additionally, because so many things already use Wi-Fi, Wi-Fi devices are prone to interference from other networks, further lowering real world speeds.
This isn’t to say that Wi-Fi is slow as it's still much faster than pretty much all LPWANs, but because Wi-Fi already uses more energy, network slowdowns make it less desirable.
There are three major new features that will interest IoT specialists:
MU-MIMO is the functionality that determines how many devices the router can simultaneously talk to on the network. In the past, as mentioned above, routers capped out at talking to 4 devices. With the release of Wi-Fi 6, that number doubles to 8. That might not sound like a big change, but it effectively means the number of devices that can be supported on a network without speed degradation (total network bandwidth notwithstanding) has doubled.
OFDMA (which is quite the mouthful) at its most basic level is a mechanism that allows the router to break up packets such that multiple users of the network can use different pieces of the same packet. This particularly improves network efficiency for low bandwidth devices or networks with large numbers of devices, which is right in line with prime IoT use cases.
Finally, scheduled check-in messages allow devices to schedule with the access point when to check in and keep the connection to the access point alive. This means that lower powered devices can schedule less frequent check-ins, wake up less often, and ultimately save on power consumption.
To sum everything up, Wi-Fi 6 brings with it a range of new features that make Wi-Fi more appealing to IoT applications that have low-bandwidth, limited access to power, and large numbers of devices. While IoT was arguably quite usable before for certain IoT projects, this serves to broaden the appeal and cement Wi-Fi as a player in the IoT field.