What are the differences between 802.11ax and 802.11ac Wi-Fi standards? Learn more in one article

In previous articles, we have introduced the origin of the 802.11ax standard and the new challenges it brings. However, when we put it together with the now widely popular 11ac standard, we may not be able to accurately and clearly distinguish the specific technical differences between the two, and even wonder, 11ac can already meet the needs of the family very well, do we really need 11ax? I believe that after reading this article, the answer will become clear.

802.11ax, also known as the "High-Efficiency Wireless" (HEW), will increase the average transmission rate of each user in a densely populated environment by more than 4 times. That is, it will provide more users with consistent and stable data streams (average transmission rate) in a high-density environment, which will effectively reduce network congestion and significantly improve wireless speed and coverage.

In addition, in addition to being backward compatible with 11a/b/n/ac, the 802.11ax standard can also increase the average transmission rate per user in high-density scenarios such as train stations and airports by 4 times.

Although 802.11ax is similar to 11ac in data rate and channel width, it can provide new modulation and coding combinations (MCS 10 and 11) with 1024-QAM. In addition, it can also perform designated downlink and uplink multi-user operations through MU-MIMO and OFDMA technology.

11ax also provides 4 times the OFDM FFT, narrower subcarrier spacing (4 times the density) and 4 times the symbol time to improve robustness and performance in multipath fading environments and outdoors, as well as traffic and channel access scenarios. Due to its better power management, it can bring longer battery life.

Based on the above “capabilities”, what target application requirements can 802.11ax achieve?

First, mobile data offload. By 2020, Wi-Fi offload traffic will reach 38.1EB per month and continue to exceed the estimated monthly mobile traffic (30.6EB), which is equivalent to moving more than 6,000 Blu-ray movies in these networks every minute;

Secondly, in an environment with a large number of access points and a high density of users with heterogeneous devices, it is important to know that “airport Wi-Fi” ≠ “home Wi-Fi”;

Third, it can adapt well to outdoor and mixed outdoor environments.

In comparison, although the 802.11ac standard can achieve a link speed of nearly 866Mbit/s in a single spatial stream, with a wider 160MHz channel and a modulation order of 256-QAM, when using 8 spatial streams (the upper limit specified by the standard), 11ac will achieve a theoretical speed of up to 6.97Gbit/s.

But! If you are not in a radio frequency laboratory, it will be difficult to achieve a high-speed wireless network of 7Gbit/s. Therefore, in a real airport terminal, whenever you want to connect to public Wi-Fi to surf the Internet or check emails, the speed is frustrating.

Another important point must be understood. We said that 802.11ac only operates on the 5GHz band, while 802.11ax can "take over" both 2.4GHz and 5GHz bands. However, 11ax also includes a major change, which is to reduce the subcarrier spacing to 1/4 of the previous 802.11 standard to preserve the existing channel bandwidth.

Moreover, 802.11ax adopts two operation modes: single user and multi-user. In single user serial mode, as long as the wireless STA (wireless base station) obtains media access rights, it will perform one data transmission and reception operation at a time; in multi-user mode, multiple non-AP STA operations can be performed simultaneously, and the standard will further divide this mode into downlink and uplink multi-user. At this point, you may find it confusing, so we made a table to compare the differences between 11ac and 11ax more intuitively:

The 802.11ax wireless standard we are talking about today actually has many technical advantages, and there are even some unfamiliar words that we have never even heard of. Putting aside those high-tech technologies, the fact that it can run on both 2.4G and 5G frequency bands is already very pleasing.

It's so powerful, when will it be widely popularized? In fact, chip manufacturers such as Broadcom, Qualcomm, Marvell, etc. have already launched chip products based on 802.11ax technology, and network equipment manufacturers such as ASUS and Ruijie have also launched corresponding home and enterprise-level products. However, terminals that can support 11ax have not yet been released. I believe that under the general trend, this is only a matter of time.