How Multi-User Technology Differs Between 802.11ac and 802.11ax

How Multi-User Technology Differs Between 802.11ac and 802.11ax

February 11, 2019

802.11ax, also referred to as WiFi 6, is the new wireless standard of 2019. It comes with a new set of complex technological features and improved performance capabilities. If you start researching the nuts and bolts of this new standard, you’ll probably see OFDMA pop up a lot. What is that and why should you care about it?

OFDMA is a mouthful for anyone to say let alone understand. It stands for Orthogonal Frequency Division Multiple Access, which is why it’s much easier to refer to it as OFDMA. Basically, this feature affects the way 802.11ax supports multi-users.

But wait, 802.11ac also features multi-user technology. Why did we need a change? Why bring in OFDMA?

For starters, we needed a change because wireless-equipped devices are growing by the billions, mostly thanks to the IoT market. Devices are diverse, dynamic, and frequently operating in dense environments. To give you a hint as to how the new standard addresses these issues – 802.11ax is heralded as the “high efficiency” standard.

That means that 802.11ax improves on the multi-user capabilities of 802.11ac by increasing the number of users that can communicate at the same time. In order to understand what’s going on here, picture three bridges crossing a river. Each bridge is wide enough for one car. On one side of the river is the Entrance. On the other side, are the Cities of Wireless Fun. Three cars at a time can go through the Entrance, onto one of the three bridges, and across to the Cities.

This is what 802.11ac introduced as multi-user. This practice allows multiple devices to transmit data (cars) at the same time, but there’s still a simultaneous user limit. If two cars get on the same bridge, they have to take turns reaching a City because the bridge is only wide enough for one car. This means an entire bridge (channel) is reserved for one car (device communication) at a time, which isn’t highly efficient.

In 802.11ax the situation changes slightly. Now, 9 bicycles approach and go through the Entrance. 3 bicycles fit on each bridge. All 3 bicycles on the bridge will reach one of the Cities of Wireless Fun at the same time. This allows for more simultaneous traffic using the bridges.

This works because 802.11ax uses channel splitting to allocate a specific piece of a channel, not the entire channel, to each device that makes a request. The new standard splits each channel into smaller frequencies, dividing those frequencies between requesting devices. Each device gets a dedicated allocation of the channel (bridge) so that more devices can communicate (send bicycles across the bridge) at one time, rather than having to take turns (waiting for one car at a time to go).

This gives the standard its high efficiency. It allows a single AP to support more clients than before, and increases data rates and reduces latency (the time it takes data communication to go from one point to another). It is particularly helpful in a high IoT environment, or an especially dense environment like a stadium.

And don’t worry that moving from cars to bicycles means your devices will operate at a slower streaming speed. Remember, 802.11ax is all about high efficiency. That doesn’t work if speeds start moving backwards. The cars and bicycles analogy is simply to share how channel (bridge) use changes under 802.11ax: more devices can communicate at a time because of frequency allocation, rather than one communication hogging the entire channel.

So, should you make the change to using access points that support 802.11ax features? This depends largely on your business needs. Do you operate in a dense environment? Do you support a lot of IoT activity? Do you see your network traffic growing? If the answer is yes, you may want to research options. Enterprise grade 802.11ax access points aren’t in widespread use today, so you certainly have time to make a decision.

Until then, get ready to see a lot more about 802.11ax, or WiFi 6, traveling around the Internet and tech world.