IEEE 802.11ac-2013
IEEE 802.11ac-2013 or 802.11ac is a wireless networking standard in the IEEE 802.11 set of protocols, providing high-throughput wireless local area networks on the 5 GHz band. The standard has been retroactively labelled as Wi-Fi 5 by Wi-Fi Alliance.
The specification has multi-station throughput of at least 1.1 gigabit per second and single-link throughput of at least 500 megabits per second. This is accomplished by extending the air-interface concepts embraced by 802.11n: wider RF bandwidth, more MIMO spatial streams, downlink multi-user MIMO, and high-density modulation.
The Wi-Fi Alliance separated the introduction of 802.11ac wireless products into two phases, named "Wave 1" and "Wave 2". From mid-2013, the alliance started certifying Wave 1 802.11ac products shipped by manufacturers, based on the IEEE 802.11ac Draft 3.0. Subsequently in 2016, Wi-Fi Alliance introduced the Wave 2 certification, which includes additional features like MU-MIMO, 160 MHz channel width support, support for more 5 GHz channels, and four spatial streams. It meant Wave 2 products would have higher bandwidth and capacity than Wave 1 products.
New technologies
New technologies introduced with 802.11ac include the following:- 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
- Downlink multi-user MIMO
- * Multiple STAs, each with one or more antennas, transmit or receive independent data streams simultaneously.
- ** Space-division multiple access : streams not separated by frequency, but instead resolved spatially, analogous to 11n-style MIMO.
- * Downlink MU-MIMO included as an optional mode.
- Modulation
- * 256-QAM, rate 3/4 and 5/6, added as optional modes.
- * 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
- * MAC modifications
- * 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 frame as opposed to 802.11n's high throughput 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 radar systems using the same frequency band.
Features
Mandatory
- Borrowed from the 802.11a/802.11g specifications:
- * 800 ns regular guard interval
- * Binary convolutional coding
- * Single spatial stream
- Newly introduced by the 802.11ac specification:
- * 80 MHz channel bandwidths
Optional
- Borrowed from the 802.11n specification:
- * Two to four spatial streams
- * Low-density parity-check code
- * Space–time block coding
- * Transmit beamforming
- * 400 ns short guard interval
- Newly introduced by the 802.11ac specification:
- * five to eight spatial streams
- * 160 MHz channel bandwidths
- * 80+80 MHz channel bonding
- * MCS 8/9
New scenarios and configurations
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. With storage locally attached through USB 2.0, filling the bandwidth made available by 802.11ac was not easily accomplished.
Example configurations
All rates assume 256-QAM, rate 5/6:| Scenario | Typical client form factor | PHY link rate | Aggregate capacity |
| One-antenna AP, one-antenna STA, 80 MHz | Handheld | 433 Mbit/s | 433 Mbit/s |
| Two-antenna AP, two-antenna STA, 80 MHz | Tablet, laptop | 867 Mbit/s | 867 Mbit/s |
| One-antenna AP, one-antenna STA, 160 MHz | Handheld | 867 Mbit/s | 867 Mbit/s |
| Three-antenna AP, three-antenna STA, 80 MHz | Laptop, PC | 1.30 Gbit/s | 1.30 Gbit/s |
| Two-antenna AP, two-antenna STA, 160 MHz | Tablet, laptop | 1.73 Gbit/s | 1.73 Gbit/s |
| Four-antenna AP, four one-antenna STAs, 160 MHz | Handheld | 867 Mbit/s to each STA | 3.39 Gbit/s |
Eight-antenna AP, 160 MHz
| Digital TV, set-top box,tablet, laptop, PC, handheld |
| 6.93 Gbit/s |
| Eight-antenna AP, four 2-antenna STAs, 160 MHz | 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.Data rates and speed
Several companies are currently offering 802.11ac chipsets with higher modulation rates: MCS-10 and MCS-11, 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.| Type | 2.4 GHz band Mbit/s | 2.4 GHz band config | 5 GHz band Mbit/s | 5 GHz band config |
| AC450 | - | - | 433 | 1 stream @ MCS 9 |
| AC600 | 150 | 1 stream @ MCS 7 | 433 | 1 stream @ MCS 9 |
| AC750 | 300 | 2 streams @ MCS 7 | 433 | 1 stream @ MCS 9 |
| AC1000 | 300 | 2 streams @ MCS 7 | 650 | 2 streams @ MCS 7 |
| AC1200 | 300 | 2 streams @ MCS 7 | 867 | 2 streams @ MCS 9 |
| AC1300 | 400 | 2 streams @ 256-QAM | 867 | 2 streams @ MCS 9 |
| AC1300 | - | - | 1,300 | 3 streams @ MCS 9 |
| AC1350 | 450 | 3 streams @ MCS 7 | 867 | 2 streams @ MCS 9 |
| AC1450 | 450 | 3 streams @ MCS 7 | 975 | 3 streams @ MCS 7 |
| AC1600 | 300 | 2 streams @ MCS 7 | 1,300 | 3 streams @ MCS 9 |
| AC1700 | 800 | 4 streams @ 256-QAM | 867 | 2 streams @ MCS 9 |
| AC1750 | 450 | 3 streams @ MCS 7 | 1,300 | 3 streams @ MCS 9 |
| AC1900 | 600 | 3 streams @ 256-QAM | 1,300 | 3 streams @ MCS 9 |
| AC2100 | 800 | 4 streams @ 256-QAM | 1,300 | 3 streams @ MCS 9 |
| AC2200 | 450 | 3 streams @ MCS 7 | 1,733 | 4 streams @ MCS 9 |
| AC2300 | 600 | 4 streams @ MCS 7 | 1,625 | 3 streams @ 1024-QAM |
| AC2400 | 600 | 4 streams @ MCS 7 | 1,733 | 4 streams @ MCS 9 |
| AC2600 | 800 | 4 streams @ 256-QAM | 1,733 | 4 streams @ MCS 9 |
| AC2900 | 750 | 3 streams @ 1024-QAM | 2,167 | 4 streams @ 1024-QAM |
| AC3000 | 450 | 3 streams @ MCS 7 | 1,300 + 1,300 | 3 streams @ MCS 9 x 2 |
| AC3150 | 1000 | 4 streams @ 1024-QAM | 2,167 | 4 streams @ 1024-QAM |
| AC3200 | 600 | 3 streams @ 256-QAM | 1,300 + 1,300 | 3 streams @ MCS 9 x 2 |
| AC5000 | 600 | 4 streams @ MCS 7 | 2,167 + 2,167 | 4 streams @ 1024-QAM x 2 |
| AC5300 | 1000 | 4 streams @ 1024-QAM | 2,167 + 2,167 | 4 streams @ 1024-QAM x 2 |