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What’s the difference between 802.11ac vs. 802.11ax?

Wireless standards documents can be hundreds of pages long and fraught with technical minutiae. But the important highlights generally boil down to a short list of talking points that differentiate one standard from its predecessor.

With the buzz about the latest Wi-Fi standard — 802.11ax, also known as Wi-Fi 6 — it’s worth examining the new standard versus its predecessor, 802.11ac, also known as Wi-Fi 5. As we compare 802.11ac vs. 802.11ax, some important differences emerge between the two specifications.

Where 802.11ac was considered evolutionary, 802.11ax has sometimes been labeled revolutionary. Even if that sounds grandiose, the new .11ax magic is different enough in several technical constructs to warrant scrutiny and to appreciate the real changes under the hood versus past standards.

802.11ac vs. 802.11ax: Key differences summarized

Some of the key differences between 802.11ac and 802.11ax include the following:

  • frequency bands;
  • spatial streams;
  • maximum data rates;
  • modulation;
  • and overall performance at the same power levels.

Let’s start with the spectrum in play for 802.11ac vs. 802.11ax. Many people don’t realize, when they buy a dual-band .11ac access point (AP), that the 2.4 GHz band reflects a much older standard — namely 802.11n. Why? 802.11ac operates only in the 5 GHz band, while 802.11ax works in both the 2.4 GHz and 5 GHz bands.

Additionally, while the .11ac standard allowed up to eight spatial streams, the hardware market stagnated at four. For 802.11ax, eight spatial stream APs are theoretically possible.

The significance here is that 802.11ac never got close to delivering its maximum potential of 6.9 Gbps because of hardware limitations. By contrast, .11ax is better positioned to deliver its own maximum of 9.6 Gbps, albeit under ideal conditions that most of us still may never achieve.

One factor that prevailed in the earliest versions of the 802.11 standard also holds true in 802.11ax. In a well-designed Wi-Fi network, you can generally expect to see better data rates at the same ranges and power levels as the technology you are replacing. Simply put, you can expect better cell quality.

802.11ax and Wi-Fi 6 promised benefits

Now to the nitty-gritty of what makes performance gains possible when considering 802.11ax vs. 802.11ac: You’ll see the 4x multiplier used fairly frequently when comparing the specifics of the two standards.

For example, .11ax, at its best, uses 1024 quadrature amplitude modulation, as opposed to .11ac’s 256 QAM scheme. This means the symbol duration for .11ax is four times wider than .11ac, which lets more data pass through in a given operational time slot. Then, there is nearly a 4x reduction in spacing between the modulated sub-carriers in .11ax, meaning that more spectrum is actually used for data transfer and less for management.

When comparing 802.11ac vs. 802.11ax, other significant developments include the following:

  • the use of orthogonal frequency-division multiple access, which lets an AP service multiple wireless clients at different bandwidth requirements simultaneously;
  • a new battery-preserving power-save methodology aimed at IoT devices;
  • bidirectional improvements in multiuser multiple input, multiple output radio processes; and
  • a feature called basic service set (BSS) coloring, which deals with co-channel interference.

As good as 802.11ac is, it has no effective way to deal with interference from neighboring cells on the same channel, which can translate into reduced performance. BSS coloring in 802.11ax adds a field to the wireless frame that overcomes issues associated with same-frequency cell coexistence, leading to increased overall capacity.

As you can see, 802.11ax has some powerful features, which is impressive when you consider that 802.11ac, as a standard, is no slouch.

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