Wi-Fi 6

IEEE 802.11ax-2021 or 802.11ax, is an IEEE standard from the Wi-Fi Alliance, for wireless networks (WLANs). The standard is marketed as Wi-Fi 6. It operates in the 2.4 GHz and 5 GHz bands, with an extended version, Wi-Fi 6E, that adds the 6 GHz band. It is an upgrade from Wi-Fi 5 (IEEE 802.11ac), with improvements for better performance in crowded places. Wi-Fi 6 covers frequencies in license-exempt ISM bands, including the commonly used 2.4 GHz and 5 GHz, as well as the broader 6 GHz band (for WiFi 6E).

This standard aims to boost throughput in crowded places like offices and malls. Though the nominal data rate is only 37% higher than that of 802.11ac, the throughput increases by at least four times, making it more efficient and reducing latency by 75%. The quintupling of overall throughput is made possible by higher spectral efficiency.

802.11ax Wi-Fi has a main feature called OFDMA, similar to how cellular common-carrier networks work. This brings better spectrum use, improved power control to avoid interference, and enhancements like 1024‑QAM, MIMO and MU-MIMO for faster speeds. There are also reliability improvements such as lower power consumption and security protocols like Target Wake Time and WPA3.

The 802.11ax standard was approved on September 1, 2020, with Draft 8 getting 95% approval. Subsequently, on February 1, 2021, the standard received official endorsement from the IEEE Standards Board.

Notes

In 802.11ac (802.11's previous amendment), multi-user MIMO was introduced, which is a spatial multiplexing technique. MU-MIMO allows the access point to form beams towards each client, while transmitting information simultaneously. By doing so, the interference between clients is reduced, and the overall throughput is increased, since multiple clients can receive data simultaneously.

With 802.11ax, a similar multiplexing is introduced in the frequency-division multiplexing: OFDMA. With OFDMA, multiple clients are assigned to different Resource Units in the available spectrum. By doing so, an 80 MHz channel can be split into multiple Resource Units, so that multiple clients receive different types of data over the same spectrum, simultaneously.

To support OFDMA, 802.11ax needs four times as many subcarriers as 802.11ac. Specifically, for 20, 40, 80, and 160 MHz channels, the 802.11ac standard has, respectively, 64, 128, 256 and 512 subcarriers while the 802.11ax standard has 256, 512, 1024, and 2048 subcarriers. Since the available bandwidths have not changed and the number of subcarriers increases by a factor of four, the subcarrier spacing is reduced by the same factor. This introduces OFDM symbols that are four times longer: in 802.11ac, an OFDM symbol takes 3.2 microseconds to transmit. In 802.11ax, it takes 12.8 microseconds (both without guard intervals).