Benutzer:Stdruwe/IEEE 802.11ac

IEEE 802.11ac ist ein sich in Entwicklung befindender Spezifikation für drahtlose Computernetzwerke (WLAN) im 5 GHz-Bereich.

Dieser Standard soll durch bei multiplen Verbindungen mind. 1 Gigabit pro Sekunde und bei Einzelverbindugen

is a wireless computer networking standard of 802.11 currently under development which will provide high-throughput wireless local area networks (WLAN) on the 5 GHz band.

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 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 8), multi-user MIMO, and high-density modulation (up to 256 QAM).

On January 20, 2011, the Initial Technical Specification Draft 0.1 was confirmed by IEEE 802.11 TGac. Standard finalization is anticipated in late 2012, with final 802.11 Working Group approval in late 2013. 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.

Quantenna released the world's first 802.11ac chipset for retail Wi-Fi routers and consumer electronics on November 15, 2011. Redpine Signals released the first low power 802.11ac technology for smartphone application processors on December 14, 2011. On January 5th, 2012, Broadcom announced its first 802.11ac Wi-Fi chips and partners and on April 27, 2012, Netgear announced the first Broadcom-enabled router. On May 14, 2012, Buffalo Technology released the world’s first 802.11ac products to market, releasing a wireless router and client bridge adapter.

New technologies

• Extended channel binding
  • 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
  • Optional beamforming with single standard sounding and feedback for compatibility between vendors (multiple 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

Mandatory and optional features

• Mandatory features (carried over from 802.11a/802.11n)
  • 800 ns Regular Guard Interval
  • Binary Convolutional Coding (BCC)
  • Single spatial stream

• New mandatory features (newly introduced in 802.11ac)
  • 80 MHz channel bandwidths

• Optional features (carried over from 802.11n)
  • 2 or more spatial streams
  • Low-density parity-check code (LDPC)
  • Space-Time Block Coding (STBC)
  • Transmit Beamforming (TxBF)
  • 400 ns Short Guard Interval (SGI)

• Optional features (newly introduced in 802.11ac)
  • 5 to 8 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.

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

Typical 1x1 data rates

Single-antenna data rates in Megabits/second are shown in the table below; a second antenna results in a doubling of the data rate, a 3rd 3x, etc... Note that the listed rates are PHY rates and not maximum achievable over-the-air transmission rates.

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

See also

• IEEE 802.11ad

Resources (White papers, technical papers, application notes)

• A brief technology introduction on the 802.11ac amendment to the 802.11-2007 standard
• A list of 802.11ac devices

Vorlage:IEEE standards [[Category:IEEE 802.11]]