IEEE 802.11ac

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IEEE 802.11ac is a wireless networking standard in the 802.11 family (which is marketed under the brand name Wi-Fi), developed in the IEEE Standards Association process,[1] providing high-throughput wireless local area networks (WLANs) on the 5 GHz band.[1] The standard was developed from 2011 through 2013 and approved in January 2014.[1][2]

This specification has expected multi-station WLAN throughput of at least 1 gigabit per second and a single link throughput of at least 500 megabits per second (500 Mbit/s). This is accomplished by extending the air interface concepts embraced by 802.11n: wider RF bandwidth (up to 160 MHz), more MIMO spatial streams (up to eight), downlink multi-user MIMO (up to four clients), and high-density modulation (up to 256-QAM).[3][4]

New technologies

New technologies introduced with 802.11ac include the following:[4]

  • Extended channel binding
    • Mandatory 80 MHz channel bandwidth for stations (vs. 40 MHz maximum in 802.11n), 160 MHz available optionally
  • 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 20/40/80/160 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

Meru Networks has suggested that 802.11ac makes a wireless network employing the Single Channel Architecture substantially more effective.[5] Traditional 802.11 networks are deployed as a Multiple Channel Architecture

Mandatory and optional features

  • Mandatory features (carried over from 802.11a/802.11g)
  • New mandatory features (newly introduced in 802.11ac)
    • 80 MHz channel bandwidths
  • Optional features (carried over from 802.11n)
  • Optional features (newly introduced in 802.11ac)
    • five to eight spatial streams
    • 160 MHz channel bandwidths (contiguous 80+80)
    • 80+80 MHz channel bonding (discontiguous 80+80)
    • MCS 8/9 (256-QAM)

New scenarios and configurations

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.[6]

With the inclusion of USB 3.0 interface, 802.11ac access points and routers can use locally attached storage to provide various services that fully utilize their WLAN capacities, such as video streaming, FTP servers, and personal cloud services.[7] 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
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 1.27 Gbit/s 1.27 Gbit/s
Two-antenna AP, two-antenna STA, 160 MHz Tablet, laptop 1.69 Gbit/s 1.69 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 (MU-MIMO)
  • one four-antenna STA
  • one two-antenna STA
  • two one-antenna STAs
Digital TV, Set-top Box,
Tablet, Laptop, PC, Handheld
  • 3.39 Gbit/s to four-antenna STA
  • 1.69 Gbit/s to two-antenna STA
  • 867 Mbit/s to each one-antenna STA
6.77 Gbit/s
Eight-antenna AP, four 2-antenna STAs, 160 MHz
Digital TV, tablet, laptop, PC 1.69 Gbit/s to each STA 6.77 Gbit/s

Data rates and speed


Theoretical throughput for single spatial stream (in Mbit/s)[8][lower-alpha 1]
index[lower-alpha 2]
20 MHz channels 40 MHz channels 80 MHz channels 160 MHz channels
800 ns GI[lower-alpha 3] 400 ns GI 800 ns GI 400 ns GI 800 ns GI 400 ns GI 800 ns GI 400 ns GI
0 BPSK 1/2 6.5 7.2 13.5 15 29.3 32.5 58.5 65
1 QPSK 1/2 13 14.4 27 30 58.5 65 117 130
2 QPSK 3/4 19.5 21.7 40.5 45 87.8 97.5 175.5 195
3 16-QAM 1/2 26 28.9 54 60 117 130 234 260
4 16-QAM 3/4 39 43.3 81 90 175.5 195 351 390
5 64-QAM 2/3 52 57.8 108 120 234 260 468 520
6 64-QAM 3/4 58.5 65 121.5 135 263.3 292.5 526.5 585
7 64-QAM 5/6 65 72.2 135 150 292.5 325 585 650
8 256-QAM 3/4 78 86.7 162 180 351 390 702 780
9 256-QAM 5/6 N/A N/A 180 200 390 433.3 780 866.7

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 are expected to become official in the 802.11ax standard (2017-2019), the successor to 802.11ac.


Type 2.4 GHz band[lower-alpha 4]
5 GHz band
AC600 150 433
AC750 300 433
AC1200 300 867
AC1300 400 867
AC1300[9] - 1,300
AC1450 450 975
AC1600 300 1,300
AC1750 450 1,300
AC1900 600[lower-alpha 5] 1,300
AC2200 450 1,733
AC2350 600[lower-alpha 5] 1,733
AC2600 800 1,733
AC3100 1000 2,167
AC3150 1000 2,167
AC3200 600[lower-alpha 5] 1,300 + 1,300[lower-alpha 6]
AC5300[12] 1000[lower-alpha 7] 2,166 + 2,166


Commercial routers and access points

Quantenna released the first 802.11ac chipset for retail Wi-Fi routers and consumer electronics on November 15, 2011.[13] Redpine Signals released the first low power 802.11ac technology for smartphone application processors on December 14, 2011.[14] On January 5, 2012, Broadcom announced its first 802.11ac Wi-Fi chips and partners[15] and on April 27, 2012, Netgear announced the first Broadcom-enabled router.[16] On May 14, 2012, Buffalo Technology released the world’s first 802.11ac products to market, releasing a wireless router and client bridge adapter.[17] On December 6, 2012, Huawei announced commercial availability of the industry's first enterprise-level 802.11ac Access Point.[18]

Apple Inc. is selling 802.11ac versions of its AirPort Extreme and AirPort Time Capsule products.[19] Motorola Solutions is selling 802.11ac access points including the AP 8232.[20] In April 2014, Hewlett-Packard started selling the HP 560 access point in the controller-based WLAN enterprise market segment.[21]

Commercial laptops

On June 7, 2012, it was reported that ASUS had unveiled its ROG G75VX gaming notebook, which will be the first consumer-oriented notebook to be fully compliant with 802.11ac[22] (albeit in its "draft 2.0" version).

In June 2013, Apple announced that the new MacBook Air features 802.11ac wireless networking capabilities,[23][24] later announcing in October 2013 that the MacBook Pro and Mac Pro also featured 802.11ac.[25][26]

As of December 2013, Hewlett-Packard incorporates 802.11ac compliance in laptop computers.[27]

Commercial handsets

Commercial tablets


See also


  1. A second stream doubles the theoretical data rate, a third one triples it, etc.
  2. MCS 9 is not applicable to all channel width/spatial stream combinations.
  3. GI stands for the guard interval.
  4. 802.11ac only specifies operation in the 5 GHz band. Operation in the 2.4 GHz band is specified by 802.11n.
  5. 5.0 5.1 5.2 With 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, commercially available devices that achieve 600 Mbit/s in the 2.4 GHz band use 3 spatial streams at 200 Mbit/s each.[10][11] This requires the use of 256-QAM modulation, which is not compliant with 802.11n and can be considered a proprietary extension.[11]
  6. As of December 2014, 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.
  7. With proprietary extension to 802.11n, using 40MHz channel in 2.4GHz, 400ns guard interval, 1024-QAM, and 4 spatial streams.


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