The specification has multi-station throughput of at least 1.1 gigabit per second (1.1 Gbit/s) and single-link throughput of at least 500 megabits per second (0.5 Gbit/s).[11] This is accomplished by extending the air-interface concepts embraced by 802.11n: wider RF bandwidth (up to 160 MHz), more MIMOspatial streams (up to eight), downlink multi-user MIMO (up to four clients), and high-density modulation (up to 256-QAM).[12][13]
The Wi-Fi Alliance separated the introduction of 802.11ac wireless products into two phases ("waves"), named "Wave 1" and "Wave 2".[14][15] From mid-2013, the alliance started certifying Wave 1 802.11ac products shipped by manufacturers, based on the IEEE 802.11ac Draft 3.0 (the IEEE standard was not finalized until later that year).[16] Subsequently in 2016, Wi-Fi Alliance introduced the Wave 2 certification, which includes additional features like MU-MIMO (down-link only), 160 MHz channel width support, support for more 5 GHz channels, and four spatial streams (with four antennas; compared to three in Wave 1 and 802.11n, and eight in IEEE's 802.11ax specification).[17] It meant Wave 2 products would have higher bandwidth and capacity than Wave 1 products.[18]
New technologies
New technologies introduced with 802.11ac include the following:[13][19]
Extended channel binding
Optional 160 MHz and mandatory 80 MHz channel bandwidth for stations; cf. 40 MHz maximum in 802.11n.
More MIMO spatial streams
Support for up to eight spatial streams (vs. four in 802.11n)
Downlink multi-user MIMO (MU-MIMO, allows up to four simultaneous downlink MU-MIMO clients)
Multiple STAs, each with one or more antennas, transmit or receive independent data streams simultaneously.
Space-division multiple access (SDMA): streams not separated by frequency, but instead resolved spatially, analogous to 11n-style MIMO.
Downlink MU-MIMO (one transmitting device, multiple receiving devices) included as an optional mode.
Modulation
256-QAM, rate 3/4 and 5/6, added as optional modes (vs. 64-QAM, rate 5/6 maximum in 802.11n).
Some vendors offer a non-standard 1024-QAM mode, providing 25% higher data rate compared to 256-QAM
Other elements/features
Beamforming with standardized sounding and feedback for compatibility between vendors (non-standard in 802.11n made it hard for beamforming to work effectively between different vendor products)
MAC modifications (mostly to support above changes)
Coexistence mechanisms for 20, 40, 80, and 160 MHz channels, 11ac and 11a/n devices
Adds four new fields to the PPDU header identifying the frame as a very high throughput (VHT) frame as opposed to 802.11n's high throughput (HT) or earlier. The first three fields in the header are readable by legacy devices to allow coexistence
DFS was mandated between channels 52 and 144 for 5 GHz to reduce interference with weather stations using the same frequency band.
The single-link and multi-station enhancements supported by 802.11ac enable several new WLAN usage scenarios, such as simultaneous streaming of HD video to multiple clients throughout the home, rapid synchronization and backup of large data files, wireless display, large campus/auditorium deployments, and manufacturing floor automation.[20]
To fully utilize their WLAN capacities, 802.11ac access points and routers have sufficient throughput to require the inclusion of a USB 3.0 interface to provide various services such as video streaming, FTP servers, and personal cloud services.[21] With storage locally attached through USB 2.0, filling the bandwidth made available by 802.11ac was not easily accomplished.
Four-antenna AP, four one-antenna STAs, 160 MHz (MU-MIMO)
Handheld
867 Mbit/s to each STA
3.39 Gbit/s
Eight-antenna AP, 160 MHz (MU-MIMO)
one four-antenna STA
one two-antenna STA
two one-antenna STAs
Digital TV, Set-top Box, Tablet, Laptop, PC, Handheld
3.47 Gbit/s to four-antenna STA
1.73 Gbit/s to two-antenna STA
867 Mbit/s to each one-antenna STA
6.93 Gbit/s
Eight-antenna AP, four 2-antenna STAs, 160 MHz (MU-MIMO)
Digital TV, tablet, laptop, PC
1.73 Gbit/s to each STA
6.93 Gbit/s
Wave 1 vs. Wave 2
Wave 2, referring to products introduced in 2016, offers a higher throughput than legacy Wave 1 products, those introduced starting in 2013. The maximum physical layer theoretical rate for Wave 1 is 1.3 Gbit/s, while Wave 2 can reach 2.34 Gbit/s. Wave 2 can therefore achieve 1 Gbit/s even if the real world throughput turns out to be only 50% of the theoretical rate. Wave 2 also supports a higher number of connected devices.[18]
Several companies are currently offering 802.11ac chipsets with higher modulation rates: MCS-10 and MCS-11 (1024-QAM), supported by Quantenna and Broadcom. Although technically not part of 802.11ac, these new MCS indices became official in the 802.11ax standard, ratified in 2021.
160 MHz channels are unavailable in some countries due to regulatory issues that allocated some frequencies for other purposes.
Advertised speeds
802.11ac-class device wireless speeds are often advertised as AC followed by a number, that number being the highest link rates in Mbit/s of all the simultaneously-usable radios in the device added up. For example, an AC1900 access point might have 600 Mbit/s capability on its 2.4 GHz radio and 1300 Mbit/s capability on its 5 GHz radio. No single client device could connect and achieve 1900 Mbit/s of throughput, but separate devices each connecting to the 2.4 GHz and 5 GHz radios could achieve combined throughput approaching 1900 Mbit/s. Different possible stream configurations can add up to the same AC number.
Quantenna released the first 802.11ac chipset for retail Wi-Fi routers and consumer electronics on November 15, 2011.[29] Redpine Signals released the first low power 802.11ac technology for smartphone application processors on December 14, 2011.[30] On January 5, 2012, Broadcom announced its first 802.11ac Wi-Fi chips and partners[31] and on April 27, 2012, Netgear announced the first Broadcom-enabled router.[32] On May 14, 2012, Buffalo Technology released the world’s first 802.11ac products to market, releasing a wireless router and client bridge adapter.[33] On December 6, 2012, Huawei announced commercial availability of the industry's first enterprise-level 802.11ac Access Point.[34]
Motorola Solutions is selling 802.11ac access points including the AP 8232.[35] In April 2014, Hewlett-Packard started selling the HP 560 access point in the controller-based WLAN enterprise market segment.[36]
Commercial laptops
On June 7, 2012, it was reported that Asus had unveiled its ROG G75VX gaming notebook, which would be the first consumer-oriented notebook to be fully compliant with 802.11ac[37] (albeit in its "draft 2.0" version).
^Wi-Fi 6E is the industry name that identifies Wi-Fi devices that operate in 6 GHz. Wi-Fi 6E offers the features and capabilities of Wi-Fi 6 extended into the 6 GHz band.
^802.11ac only specifies operation in the 5 GHz band. Operation in the 2.4 GHz band is specified by 802.11n.
^ ab802.11ac only specifies operation in the 5 GHz band. Operation in the 2.4 GHz band is specified by 802.11n.
^MCS 9 is not applicable to all channel width/spatial stream combinations.
^ abcWith 802.11n, 600 Mbit/s in the 2.4 GHz band can be achieved by using four spatial streams at 150 Mbit/s each. As of December 2014[update], commercially available devices that achieve 600 Mbit/s in the 2.4 GHz band use 3 spatial streams at 200 Mbit/s each.[26][27] This requires the use of 256-QAM modulation, which is not compliant with 802.11n and can be considered a proprietary extension.[27]
^ abcWith proprietary extension to 802.11n, using 40MHz channel in 2.4GHz, 400ns guard interval, 1024-QAM, and 4 spatial streams.
^As of December 2014[update], commercially available AC3200 devices use two separate radios with 1,300 Mbit/s each to achieve 2,600 Mbit/s total in the 5 GHz band.
^ abIEEE 802.11y-2008 extended operation of 802.11a to the licensed 3.7 GHz band. Increased power limits allow a range up to 5,000 m. As of 2009[update], it is only being licensed in the United States by the FCC.
^ abcdefghiBased on short guard interval; standard guard interval is ~10% slower. Rates vary widely based on distance, obstructions, and interference.
^ abcdefghFor single-user cases only, based on default guard interval which is 0.8 microseconds. Since multi-user via OFDMA has become available for 802.11ax, these may decrease. Also, these theoretical values depend on the link distance, whether the link is line-of-sight or not, interferences and the multi-path components in the environment.
^ abThe default guard interval is 0.8 microseconds. However, 802.11ax extended the maximum available guard interval to 3.2 microseconds, in order to support Outdoor communications, where the maximum possible propagation delay is larger compared to Indoor environments.
^"What is Wi-Fi 8?". everythingrf.com. March 25, 2023. Retrieved January 21, 2024.
^Giordano, Lorenzo; Geraci, Giovanni; Carrascosa, Marc; Bellalta, Boris (November 21, 2023). "What Will Wi-Fi 8 Be? A Primer on IEEE 802.11bn Ultra High Reliability". arXiv:2303.10442.
^IEEE Standard for Information Technology- Telecommunications and Information Exchange Between Systems- Local and Metropolitan Area Networks- Specific Requirements Part Ii: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. (n.d.). doi:10.1109/ieeestd.2003.94282