| Generation | IEEE standard | Adopted | Maximum link rate (Mbit/s) | Radio frequency (GHz) |
|---|---|---|---|---|
| Wi-Fi 8 | 802.11bn | 2028 | 100,000[1] | 2.4, 5, 6, 7, 42.5, 71[2] |
| Wi-Fi 7 | 802.11be | 2024 | 1376–46,120 | 2.4, 5, 6[3] |
| Wi-Fi 6E | 802.11ax | 2020 | 574–9608[4] | 6[a] |
| Wi-Fi 6 | 2019 | 2.4, 5 | ||
| Wi-Fi 5 | 802.11ac | 2014 | 433–6933 | 5[b] |
| Wi-Fi 4 | 802.11n | 2008 | 72–600 | 2.4, 5 |
| (Wi-Fi 3)* | 802.11g | 2003 | 6–54 | 2.4 |
| (Wi-Fi 2)* | 802.11a | 1999 | 5 | |
| (Wi-Fi 1)* | 802.11b | 1999 | 1–11 | 2.4 |
| (Wi-Fi 0)* | 802.11 | 1997 | 1–2 | 2.4 |
| *Wi‑Fi 0, 1, 2, and 3 are named by retroactive inference. They do not exist in the official nomenclature.[5][6][7] | ||||
Wi-Fi 6, or IEEE 802.11ax, is an IEEE standard from the Wi-Fi Alliance, for wireless networks (WLANs). It operates in the 2.4 GHz and 5 GHz bands,[8] with an extended version, Wi-Fi 6E, that adds the 6 GHz band.[9] It is an upgrade from Wi-Fi 5 (802.11ac), with improvements for better performance in crowded places. Wi-Fi 6 covers frequencies in license-exempt bands between 1 and 7.125 GHz, including the commonly used 2.4 GHz and 5 GHz, as well as the broader 6 GHz band.[10]
This standard aims to boost data speed (throughput-per-area[c]) in crowded places like offices and malls. Though the nominal data rate is only 37%[11] better than 802.11ac, the total network speed increases by 300%,[12] making it more efficient and reducing latency by 75%.[13] The quadrupling of overall throughput is made possible by a higher spectral efficiency.
802.11ax Wi-Fi has a main feature called OFDMA, similar to how cell technology works with Wi-Fi.[11] 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.[14]
Rate set
| MCS index[i] | Modulation type | Coding rate | Data rate (Mbit/s)[ii] | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 20 MHz channels | 40 MHz channels | 80 MHz channels | 160 MHz channels | |||||||
| 1600 ns GI[iii] | 800 ns GI | 1600 ns GI | 800 ns GI | 1600 ns GI | 800 ns GI | 1600 ns GI | 800 ns GI | |||
| 0 | BPSK | 1/2 | 8 | 8.6 | 16 | 17.2 | 34 | 36.0 | 68 | 72 |
| 1 | QPSK | 1/2 | 16 | 17.2 | 33 | 34.4 | 68 | 72.1 | 136 | 144 |
| 2 | QPSK | 3/4 | 24 | 25.8 | 49 | 51.6 | 102 | 108.1 | 204 | 216 |
| 3 | 16-QAM | 1/2 | 33 | 34.4 | 65 | 68.8 | 136 | 144.1 | 272 | 282 |
| 4 | 16-QAM | 3/4 | 49 | 51.6 | 98 | 103.2 | 204 | 216.2 | 408 | 432 |
| 5 | 64-QAM | 2/3 | 65 | 68.8 | 130 | 137.6 | 272 | 288.2 | 544 | 576 |
| 6 | 64-QAM | 3/4 | 73 | 77.4 | 146 | 154.9 | 306 | 324.4 | 613 | 649 |
| 7 | 64-QAM | 5/6 | 81 | 86.0 | 163 | 172.1 | 340 | 360.3 | 681 | 721 |
| 8 | 256-QAM | 3/4 | 98 | 103.2 | 195 | 206.5 | 408 | 432.4 | 817 | 865 |
| 9 | 256-QAM | 5/6 | 108 | 114.7 | 217 | 229.4 | 453 | 480.4 | 907 | 961 |
| 10 | 1024-QAM | 3/4 | 122 | 129.0 | 244 | 258.1 | 510 | 540.4 | 1021 | 1081 |
| 11 | 1024-QAM | 5/6 | 135 | 143.4 | 271 | 286.8 | 567 | 600.5 | 1134 | 1201 |
Notes
OFDMA
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 domain: 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, 1,024, and 2,048 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).
Technical improvements
The 802.11ax amendment brings several key improvements over 802.11ac. 802.11ax addresses frequency bands between 1 GHz and 6 GHz.[15] Therefore, unlike 802.11ac, 802.11ax also operates in the unlicensed 2.4 GHz band. Wi-Fi 6E introduces operation at frequencies of or near 6 GHz, and superwide channels that are 160 MHz wide,[16] the frequency ranges these channels can occupy and the number of these channels depends on the country the Wi-Fi 6 network operates in.[17] To meet the goal of supporting dense 802.11 deployments, the following features have been approved.
| Feature | 802.11ac | 802.11ax | Comment |
|---|---|---|---|
| OFDMA | Not available | Centrally controlled medium access with dynamic assignment of 26, 52, 106, 242(?), 484(?), or 996(?) tones per station. Each tone consists of a single subcarrier of 78.125 kHz bandwidth. Therefore, bandwidth occupied by a single OFDMA transmission is between 2.03125 MHz and ca. 80 MHz bandwidth. | OFDMA segregates the spectrum in time-frequency resource units (RUs). A central coordinating entity (the AP in 802.11ax) assigns RUs for reception or transmission to associated stations. Through the central scheduling of the RUs, contention overhead can be avoided, which increases efficiency in scenarios of dense deployments. |
| Multi-user MIMO (MU-MIMO) | Available in Downlink direction | Available in Downlink and Uplink direction | With downlink MU-MIMO an AP may transmit concurrently to multiple stations and with uplink MU-MIMO an AP may simultaneously receive from multiple stations. Whereas OFDMA separates receivers to different RUs, with MU-MIMO the devices are separated to different spatial streams. In 802.11ax, MU-MIMO and OFDMA technologies can be used simultaneously. To enable uplink MU transmissions, the AP transmits a new control frame (Trigger) which contains scheduling information (RUs allocations for stations, modulation and coding scheme (MCS) that shall be used for each station). Furthermore, Trigger also provides synchronization for an uplink transmission, since the transmission starts SIFS after the end of Trigger. |
| Trigger-based Random Access | Not available | Allows performing UL OFDMA transmissions by stations which are not allocated RUs directly. | In Trigger frame, the AP specifies scheduling information about subsequent UL MU transmission. However, several RUs can be assigned for random access. Stations which are not assigned RUs directly can perform transmissions within RUs assigned for random access. To reduce collision probability (i.e. situation when two or more stations select the same RU for transmission), the 802.11ax amendment specifies special OFDMA back-off procedure. Random access is favorable for transmitting buffer status reports when the AP has no information about pending UL traffic at a station. |
| Spatial frequency reuse | Not available | Coloring enables devices to differentiate transmissions in their own network from transmissions in neighboring networks. Adaptive power and sensitivity thresholds allows dynamically adjusting transmit power and signal detection threshold to increase spatial reuse. | Without spatial reuse capabilities devices refuse transmitting concurrently to transmissions ongoing in other, neighboring networks. With basic service set coloring (BSS coloring), a wireless transmission is marked at its very beginning, helping surrounding devices to decide if a simultaneous use of the wireless medium is permissible. A station is allowed to consider the wireless medium as idle and start a new transmission even if the detected signal level from a neighboring network exceeds legacy signal detection threshold, provided that the transmit power for the new transmission is appropriately decreased. |
| NAV | Single NAV | Two NAVs | In dense deployment scenarios, NAV value set by a frame originated from one network may be easily reset by a frame originated from another network, which leads to misbehavior and collisions. To avoid this, each 802.11ax station will maintain two separate NAVs — one NAV is modified by frames originated from a network the station is associated with, the other NAV is modified by frames originated from overlapped networks. |
| Target Wake Time (TWT) | Not available | TWT reduces power consumption and medium access contention. | TWT is a concept developed in 802.11ah. It allows devices to wake up at other periods than the beacon transmission period. Furthermore, the AP may group devices to different TWT periods, thereby reducing the number of devices contending simultaneously for the wireless medium. |
| Fragmentation | Static fragmentation | Dynamic fragmentation | With static fragmentation, all fragments of a data packet are of equal size, except for the last fragment. With dynamic fragmentation, a device may fill available RUs of other opportunities to transmit up to the available maximum duration. Thus, dynamic fragmentation helps reduce overhead. |
| Guard interval duration | 0.4 µs or 0.8 µs | 0.8 µs, 1.6 µs or 3.2 µs | Extended guard interval durations allow for better protection against signal delay spread as it occurs in outdoor environments. |
| Symbol duration | 3.2 µs | 12.8 µs | Since the subcarrier spacing is reduced by a factor of four, the OFDM symbol duration is increased by a factor of four as well. Extended symbol durations allow for increased efficiency.[18] |
| Frequency bands | 5 GHz only | 2.4 GHz and 5 GHz | 802.11ac falls back to 802.11n for the 2.4 GHz band. |
Notes
Comparison
| Frequency range, or type | PHY | Protocol | Release date [19] | Frequency | Bandwidth | Stream data rate [20] | Allowable MIMO streams | Modulation | Approximate range | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Indoor | Outdoor | |||||||||||
| (GHz) | (MHz) | (Mbit/s) | ||||||||||
| 1–7 GHz | DSSS[21], | 802.11-1997 | June 1997 | 2.4 | 22 | 1, 2 | — | DSSS, | 20 m (66 ft) | 100 m (330 ft) | ||
| HR/DSSS [21] | 802.11b | September 1999 | 2.4 | 22 | 1, 2, 5.5, 11 | — | CCK, DSSS | 35 m (115 ft) | 140 m (460 ft) | |||
| OFDM | 802.11a | September 1999 | 5 | 5, 10, 20 | 6, 9, 12, 18, 24, 36, 48, 54 (for 20 MHz bandwidth, divide by 2 and 4 for 10 and 5 MHz) | — | OFDM | 35 m (115 ft) | 120 m (390 ft) | |||
| 802.11j | November 2004 | 4.9, 5.0 [B][22] | ? | ? | ||||||||
| 802.11y | November 2008 | 3.7 [C] | ? | 5,000 m (16,000 ft)[C] | ||||||||
| 802.11p | July 2010 | 5.9 | 200 m | 1,000 m (3,300 ft)[23] | ||||||||
| 802.11bd | December 2022 | 5.9, 60 | 500 m | 1,000 m (3,300 ft) | ||||||||
| ERP-OFDM[24] | 802.11g | June 2003 | 2.4 | 38 m (125 ft) | 140 m (460 ft) | |||||||
| HT-OFDM [25] | 802.11n (Wi-Fi 4) | October 2009 | 2.4, 5 | 20 | Up to 288.8[D] | 4 | MIMO-OFDM (64-QAM) | 70 m (230 ft) | 250 m (820 ft)[26] | |||
| 40 | Up to 600[D] | |||||||||||
| VHT-OFDM [25] | 802.11ac (Wi-Fi 5) | December 2013 | 5 | 20 | Up to 693[D] | 8 | DL MU-MIMO OFDM (256-QAM) | 35 m (115 ft)[27] | ? | |||
| 40 | Up to 1600[D] | |||||||||||
| 80 | Up to 3467[D] | |||||||||||
| 160 | Up to 6933[D] | |||||||||||
| HE-OFDMA | 802.11ax (Wi-Fi 6, Wi-Fi 6E) | May 2021 | 2.4, 5, 6 | 20 | Up to 1147[E] | 8 | UL/DL MU-MIMO OFDMA (1024-QAM) | 30 m (98 ft) | 120 m (390 ft) [F] | |||
| 40 | Up to 2294[E] | |||||||||||
| 80 | Up to 4804[E] | |||||||||||
| 80+80 | Up to 9608[E] | |||||||||||
| EHT-OFDMA | 802.11be (Wi-Fi 7) | Dec 2024 (est.) | 2.4, 5, 6 | 80 | Up to 11.5 Gbit/s[E] | 16 | UL/DL MU-MIMO OFDMA (4096-QAM) | 30 m (98 ft) | 120 m (390 ft) [F] | |||
| 160 (80+80) | Up to 23 Gbit/s[E] | |||||||||||
| 240 (160+80) | Up to 35 Gbit/s[E] | |||||||||||
| 320 (160+160) | Up to 46.1 Gbit/s[E] | |||||||||||
| UHR | 802.11bn (Wi-Fi 8) | May 2028 (est.) | 2.4, 5, 6, 42, 60, 71 | 320 | Up to 100000 (100 Gbit/s) | 16 | Multi-link MU-MIMO OFDM (8192-QAM) | ? | ? | |||
| WUR [G] | 802.11ba | October 2021 | 2.4, 5 | 4, 20 | 0.0625, 0.25 (62.5 kbit/s, 250 kbit/s) | — | OOK (multi-carrier OOK) | ? | ? | |||
| mmWave (WiGig) | DMG [28] | 802.11ad | December 2012 | 60 | 2160 (2.16 GHz) | Up to 8085[29] (8 Gbit/s) | — | 3.3 m (11 ft)[30] | ? | |||
| 802.11aj | April 2018 | 60 [H] | 1080[31] | Up to 3754 (3.75 Gbit/s) | — | single carrier, low-power single carrier[A] | ? | ? | ||||
| CMMG | 802.11aj | April 2018 | 45 [H] | 540, 1080 | Up to 15015[32] (15 Gbit/s) | 4 [33] | OFDM, single carrier | ? | ? | |||
| EDMG [34] | 802.11ay | July 2021 | 60 | Up to 8640 (8.64 GHz) | Up to 303336[35] (303 Gbit/s) | 8 | OFDM, single carrier | 10 m (33 ft) | 100 m (328 ft) | |||
| Sub 1 GHz (IoT) | TVHT [36] | 802.11af | February 2014 | 0.054– 0.79 | 6, 7, 8 | Up to 568.9[37] | 4 | MIMO-OFDM | ? | ? | ||
| S1G [36] | 802.11ah | May 2017 | 0.7, 0.8, 0.9 | 1–16 | Up to 8.67[38] (@2 MHz) | 4 | ? | ? | ||||
| Light (Li-Fi) | LC (VLC/OWC) | 802.11bb | December 2023 (est.) | 800–1000 nm | 20 | Up to 9.6 Gbit/s | — | O-OFDM | ? | ? | ||
(IrDA) | 802.11-1997 | June 1997 | 850–900 nm | ? | 1, 2 | — | ? | ? | ||||
| 802.11 Standard rollups | ||||||||||||
| 802.11-2007 (802.11ma) | March 2007 | 2.4, 5 | Up to 54 | DSSS, OFDM | ||||||||
| 802.11-2012 (802.11mb) | March 2012 | 2.4, 5 | Up to 150[D] | DSSS, OFDM | ||||||||
| 802.11-2016 (802.11mc) | December 2016 | 2.4, 5, 60 | Up to 866.7 or 6757[D] | DSSS, OFDM | ||||||||
| 802.11-2020 (802.11md) | December 2020 | 2.4, 5, 60 | Up to 866.7 or 6757[D] | DSSS, OFDM | ||||||||
| 802.11me | September 2024 (est.) | 2.4, 5, 6, 60 | Up to 9608 or 303336 | DSSS, OFDM | ||||||||
References
External links
- Evgeny Khorov, Anton Kiryanov, Andrey Lyakhov, Giuseppe Bianchi. 'A Tutorial on IEEE 802.11ax High Efficiency WLANs', IEEE Communications Surveys & Tutorials, vol. 21, no. 1, pp. 197–216, First quarter 2019. doi:10.1109/COMST.2018.2871099
- Bellalta, Boris (2015). "IEEE 802.11ax: High-Efficiency WLANs". IEEE Wireless Communications. 23: 38–46. arXiv:1501.01496. doi:10.1109/MWC.2016.7422404. S2CID 15023432.
- Shein, Esther (November 30, 2021). "Deloitte: Don't rule out Wi-Fi 6 as a next-generation wireless network". TechRepublic. Archived from the original on 2022-01-19.