IEEE 802.11ac is a wireless networking standard in the 802.11 family, developed in the IEEE
Standards Association process, providing high-throughput wireless local area networks 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. 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.
New technologies New technologies introduced with 802.11ac
include the following: Extended channel binding
Mandatory 80 MHz channel bandwidth for stations, 160 MHz available optionally
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 Controversy has been raised in 3GPP RAN Plenary
that this modulation rate is not suitable for any architecture other than extremely
small cells and would be completely useless to 3GPP.
Other elements/features Beamforming with standardized sounding and
feedback for compatibility between vendors MAC modifications
Coexistence mechanisms for 2080/160 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.
Mandatory and optional features Mandatory features
800 ns regular guard interval Binary convolutional coding
Single spatial stream
New mandatory features 80 MHz channel bandwidths
Optional features 2 to 4 spatial streams
Low-density parity-check code Space-Time Block Coding
Transmit Beamforming 400 ns Short Guard Interval
Optional features 5 to 8 spatial streams
160 MHz channel bandwidths 80+80 MHz channel bonding
MCS 8/9
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. 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. With storage locally attached through USB 2.0, filling the bandwidth
made available by 802.11ac was not easily doable.
Example configurations All rates assume 256-QAM, rate 5/6:
Data rates and speed Note: A second stream doubles the theoretical
data rate, a 3rd 3x, etc. Note: MCS 9 is not applicable to all channel width/spatial stream
combinations Products
Commercial routers Quantenna released the 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 5, 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. Apple Inc. is selling 802.11ac versions of
its AirPort Extreme and AirPort Time Capsule products. Motorola Solutions is selling 802.11ac
access points including the AP 8232. In April 2014, Hewlett-Packard started selling the
HP 560 access point in the controller-based WLAN enterprise market segment.
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. Hewlett-Packard as of December 2013 incorporates
802.11ac compliance in laptop computers. Apple announced in June 2013 that the new
MacBook Air features 802.11ac wireless networking capabilities, later announcing in October
2013 that the MacBook Pro and Mac Pro also featured 802.11ac.
Commercial handsets HTC announced the first 802.11ac-enabled handset,
the HTC One, on February 19, 2013. The phone uses the Broadcom BCM4335 chipset.
The Samsung Galaxy S4, announced on March 14, 2013, also uses the BCM4335.
The Samsung Galaxy Note 3, announced in September 2013, is an 802.11ac-enabled handset.
The Samsung Galaxy Round, announced on October 9, 2013, is an 802.11ac-enabled handset.
The LG Nexus 5, announced in October 2013, is an 802.11ac-enabled handset. The phone
uses the Broadcom BCM4339 chipset. Nokia Lumia Icon, introduced in February 2014,
is an 802.11ac-enabled handset. Chipsets
See also IEEE 802.11ad
References
External links A brief technology introduction on the 802.11ac
amendment to the 802.11-2007 standard A list of 802.11ac devices
The Not So Definitive Guide to Beamforming Understanding IEEE 802.11ac Wi-Fi Standard
and Preparing the Enterprise WLAN MIMO 802.11ac Test Architectures
802.11ac: The Fifth Generation of Wi-Fi Technical Paper