IEEE 802.11ac

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IEEE 802.11ac is a wireless computer networking standard of 802.11, currently under development (Draft 5.0[1]), providing high-throughput wireless local area networks on the 5 GHz band[1] and is backward compatible with 802.11n's 2.4 GHz band. Standard finalization is in late 2012, with final 802.11 Working Group approval in early 2014.[1] 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.[2]

Theoretically, this specification will enable 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 8), multi-user MIMO, and high-density modulation (up to 256 QAM).

Contents

New technologies [edit]

  • Extended channel binding
    • Mandatory 80 MHz channel bandwidth for STAs (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)
  • 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)
    • Controversy has been raised 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 (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

Mandatory and optional features [edit]

  • Mandatory features (carried over from 802.11a/802.11g)
    • 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 (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 [edit]

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.[3]

Example configurations [edit]

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 1.69 Gbit/s 1.69 Gbit/s
4-antenna AP, four 1-antenna STAs, 160MHz
(MU-MIMO)		 Handheld 867 Mbit/s to each STA 3.39 Gbit/s
8-antenna AP, 160MHz (MU-MIMO)
-- one 4-antenna STA
-- one 2-antenna STA
-- two 1-antenna STAs		 Digital TV, Set-top Box,
Tablet, Laptop, PC, Handheld		 3.39 Gbit/s to 4-antenna STA
1.69 Gbit/s to 2-antenna STA
867 Mbit/s to each 1-antenna STA		 6.77 Gbit/s
8-antenna AP, four 2-antenna STAs, 160MHz
(MU-MIMO)		 Digital TV, Tablet, Laptop, PC 1.69 Gbit/s to each STA 6.77 Gbit/s

Data rates [edit]

Theoretical throughput for single Spatial Stream (in Mb/s)
MCS
index		 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 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

Note: A second stream doubles the theoretical data rate, a 3rd 3x, etc.

Products [edit]

Commercial Routers [edit]

Quantenna released the first 802.11ac chipset for retail Wi-Fi routers and consumer electronics on November 15, 2011.[4] Redpine Signals released the first low power 802.11ac technology for smartphone application processors on December 14, 2011.[5] On January 5, 2012, Broadcom announced its first 802.11ac Wi-Fi chips and partners[6] and on April 27, 2012, Netgear announced the first Broadcom-enabled router.[7] On May 14, 2012, Buffalo Technology released the world’s first 802.11ac products to market, releasing a wireless router and client bridge adapter.[8] 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[9] (albeit in its "draft 2.0" version).

Commercial handsets [edit]

HTC announced the first 802.11ac-enabled handset, the HTC One/M7 [10] on February 19, 2013. The phone uses the BCM4335 [11].

The Samsung Galaxy S4, announced on March 14, 2013, also uses the BCM4335[12].

Chipsets [edit]

Vendor Part # Streams LDPC TxBF 256-QAM Applications
Broadcom 4360 3 Y Y Y Routers
Broadcom 4352 2 Y Y Y Tablets
Broadcom 4335 1 Y Y Y Handsets
Marvell Avastar 88W8897 2 Y Y Y Tablets
Marvell Avastar 88W8864 3 Y Y Y Routers
Qualcomm WCN3680 1 Y Y Y Handsets
Qualcomm QCA9862 2 Y N Y Tablets
Qualcomm QCA9860 3 Y N Y Routers
MediaTek MT7610 1  ?  ?  ? PC (PCIe or USB)
MediaTek MT7650 1  ? Y Y Handsets
Quantenna QAC2300 4 Y Y Y Routers
Redpine Signals RS9117 1 Y  ? Y Handsets
Redpine Signals RS9333 3 Y  ? Y Routers

See also [edit]

References [edit]

  1. ^ a b c "Official IEEE 802.11 Working Group Project Timelines". 2012-11-03. 
  2. ^ Shankland, Stephen (2011-02-08). "Study: Expect a billion 802.11ac Wi-Fi devices in 2015". Cnet. 
  3. ^ de Vegt, Rolf (2008-11-10). "802.11ac Usage Models Document". 
  4. ^ "Quantenna Launches World's First 802.11ac Gigabit-Wireless Solution for Retail Wi-Fi Routers and Consumer Electronics" (Press release). Quantenna. 2011-11-15. 
  5. ^ "Redpine Signals Releases First Ultra Low Power 802.11ac Technology for Smartphone Application Processors" (Press release). Redpine Signals. 2011-12-14. Retrieved 2013-03-15. 
  6. ^ "Broadcom Launches First Gigabit Speed 802.11ac Chips - Opens 2012 CES with 5th Generation (5G) Wi-Fi Breakthrough" (Press release). Broadcom. 2012-01-05. Retrieved 2013-03-15. 
  7. ^ Netgear's R6300 router is first to use Broadcom 802.11ac chipset, will ship next month for $200
  8. ^ "Buffalo's 802.11ac Wireless Solutions Available Now" (Press release). Austin, Texas: Buffalo Technology (via PRNewswire). May 14, 2012. Retrieved 2013-03-15. 
  9. ^ "Asus gaming notebook first to feature full 802.11ac". Electronista. 2012-06-07. Retrieved 2013-03-15. 
  10. ^ "HTC One/M7 specs". 
  11. ^ "BCM4335". 
  12. ^ "BCM4335". 

External links [edit]
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