What is 802.11ax Wi-Fi?

Written by: Paul Sweeney | May 30, 2018

As the number, and performance, of devices exponentially increases, so does the demand placed upon the wireless network.

Throw the much vaunted Internet of Things (IoT) revolution into the mix, and the need to increase the capacity of a wireless network, as well the underlying throughput, is apparent if all these devices are going to connect satisfactorily.

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The evolution of Wi-Fi over the past 20 years has been one of quicker-and-quicker throughput, and 802.11ax doesn't disappoint with 10 Gbps advertised on the tin.

While 10 Gbps sounds great - and it is - you shouldn't focus on what that means to individual users accessing the Wi-Fi – rather, its significance really comes to light to an IT department trying to deal with ever-greater volumes of users with ever-more devices and ever-more-demanding applications.

As a recent blog authored by Aerohive's Wi-Fi Guru David Coleman stated:- 

"Past amendments defined 802.11 higher data rates and wider channels, but did not address efficiency. The bulk of 802.11 data frames (75-80%) are small and under 256 bytes. The result is excessive overhead at the MAC sublayer and medium contention overhead for each small frame. Higher data rates and wider channels is not the goal of 802.11ax. The goal is better and more efficient 802.11 traffic management. Another goal is to increase the average throughput 4X per user in high-density WLAN environments."

The next wireless chapter is no longer just about throughput, it’s about capacity and efficiency. Capacity is a function of how rapidly and reliably you can get your data on and off the air, thereby leaving more time (and thus capacity) for others.

This is particularly useful in high density environments such as conference centers, stadiums and lecture halls, where hundreds of people are looking to connect multiple devices to the wireless network. 

All this congestion and medium contention overhead means that efficiency at the MAC sublayer drops due to an increase in collisions. 802.11ax uses PHY and MAC layer enhancements for better traffic management of ALL those frames that need to be passed.

Previously users could only use one channel at a time, and a client would effectively take turns broadcasting or listening to the network.

802.11ax offers a big step forward with its Orthogonal Frequency Division Multiple Access (ODMFA), meaning multiple users with varying bandwidth needs can be served simultaneously.

Wi-Fi to date has been akin to a delivery van delivering one package per trip. 802.11ax, utilising ODMFA, divides up the spectrum, making it available to multiple users at once.

This changes the Wi-Fi from a van carrying on package to a lorry carrying multiple packages to multiple destination - a more efficient use of resources.

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