IEEE 802.11ac

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IEEE 802.11ac is a wireless computer networking standard of 802.11 currently under development which will provide high throughput Wireless Local Area Networks (WLAN) below 6 GHz (what is commonly known as the 5 GHz band).[1]
Theoretically, this specification will enable multi-station WLAN throughput of at least 1 Gigabit per second and a maximum single link throughput of at least 500 megabit 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 8), multi-user MIMO, and high-density modulation (up to 256 QAM).
On January 20, 2011, the Initial Technical Specification Draft 0.1[2] was confirmed by IEEE 802.11 TGac.[3] Standard finalization is anticipated in late 2012, with final 802.11 Working Group approval in late 2013.[1] According to a study, devices with the 802.11ac specification are expected to become common by 2015 with an estimated one billion spread around the world.[4]
Quantenna released[5] the world's first 802.11ac chipset for retail wi-fi routers and consumer electronics on November 15, 2011. Redpine Signals released[6] the first low power 802.11ac technology for smartphone application processors on December 14, 2011. On January 5th, 2012, Broadcom announced[7] its first 802.11ac Wi-Fi chips and partners.
Contents  [hide]
1 New technologies
2 New scenarios and configurations
2.1 Example configurations
3 See also
4 References
[edit]New technologies

Wider channel bandwidths
80 MHz and 160 MHz channel bandwidths (vs. 40 MHz maximum in 802.11n)
80 MHz mandatory for stations (STAs), 160 MHz optional
More MIMO spatial streams
Support for up to 8 spatial streams (vs. 4 in 802.11n)
Multi-user MIMO (MU-MIMO)
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
Single sounding and feedback format for beamforming (vs. multiple in 802.11n)
MAC modifications (mostly to support above changes)
Coexistence mechanisms for 20/40/80/160 MHz channels, 11ac and 11a/n devices
[edit]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.[8]
[edit]Example configurations
All rates assume 256-QAM, rate 5/6:
Scenario Typical Client
Form Factor PHY Link Rate Aggregate
Capacity
1-antenna AP, 1-antenna STA, 80MHz Handheld 433 Mbit/s 433 Mbit/s
2-antenna AP, 2-antenna STA, 80MHz Tablet, Laptop 867 Mbit/s 867 Mbit/s
1-antenna AP, 1-antenna STA, 160MHz Handheld 867 Mbit/s 867 Mbit/s
2-antenna AP, 2-antenna STA, 160MHz Tablet, Laptop 1.73 Gbit/s 1.73 Gbit/s
4-antenna AP, 4 1-antenna STAs, 160MHz
(MU-MIMO) Handheld 867 Mbit/s to each STA 3.47 Gbit/s
8-antenna AP, 160MHz (MU-MIMO)
-- 1 4-antenna STA
-- 1 2-antenna STA
-- 2 1-antenna STAs Digital TV, Set-top Box,
Tablet, Laptop, PC, Handheld 3.47 Gbit/s to 4-antenna STA
1.73 Gbit/s to 2-antenna STA
867 Mbit/s to each 1-antenna STA 6.93 Gbit/s
8-antenna AP, 4 2-antenna STAs, 160MHz
(MU-MIMO) Digital TV, Tablet, Laptop, PC 1.73 Gbit/s to each STA 6.93 Gbit/s