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, providing high-throughput wireless local area networks (WLANs) on the 5 GHz band. The standard was developed from 2011 through 2013 and approved in January 2014. According to a study, devices with the 802.11ac specification are expected to be common by 2015 with an estimated one billion spread around the world.
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).
Introduced with 802.11ac include the following:
- 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)
- 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
802.11ac is an example of a wireless network employing the Single Channel Architecture whereas previous generations of 802.11 were primarily using Multiple Channel Architecture.
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).
Introduced with 802.11ac include the following:
- 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)
- 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
802.11ac is an example of a wireless network employing the Single Channel Architecture whereas previous generations of 802.11 were primarily using Multiple Channel Architecture.