WLAN 802.11ac Tutorial

This WLAN 802.11ac tutorial covers 11ac features,802.11ac frame format,802.11ac physical layer, 802.11ac MAC layer,802.11ac beamforming,spectral mask,data rates and 802.11ac radio network planning. It covers following.


This standard is one of the series of WLAN standards and its evolution is after IEEE 802.11n. This 802.11ac technology is developed to provide data rate in Gbps for wireless devices mainly for WLAN applications. In the previous versions of 802.11 series of standards were designed for single user operation. In 802.11ac multi user concept was introduced with multiuser MIMO feature. Beamforming has been added to cover more region and specific region with the focused beam concept.

802.11ac features

Following are silent features of 802.11ac. As mentioned 11ac products are available in 5GHz frequency band only and not available for 2.4GHz frequency band unlike 11n.

• Frequency range : 5 GHz
• Modulation Scheme: OFDM and DSSS/CCK
• Backward compatibility: It supports legacy 11n systems
• Data modulation:Supports BPSK,QPSK,16QAM,64 QAM,256QAM designated by MCS0 to MCS9
• Channel Bandwidth: 20MHz,40MHz,80MHz,160MHz
• OFDM data subcarriers/pilots : 52/4 ,108/6, 234/8, 468/16
• OFDM coding rate: 5/6
• Short guard interval : 400 ns
• Max. Spatial streams Supported: 8
• 64,128,256,512 FFT sizes • Max. Data rate: 6.93Gbps using 160MHz bandwidth,8 spatial streams,MCS9,256QAM,with short guard interval
•  Distance: About 80 m with 3 antenna(about 10 meter more than 11n) • MIMO configuration : 4 X 4 • Supports Only NDP(Null Data Packet) explicit beamforming
• Supports single user transmission as well as multi-user transmission
•  PHY layer frame(VHT mode) consists of L-STF,L-LTF,L-SIG,VHT-SIG-A,VHT-STF,VHT-LTF,VHT-SIG-B and Data part.

WLAN 802.11ac Frame Structure

802.11ac physical layer frame format

Figure-1 depicts WLAN 802.11ac frame Structure. As shown it consists of L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B & Data part.

WLAN 802.11ac PHY Layer

802.11ac physical layer

Figure-2 depicts WLAN 802.11ac Physical layer transmitter part.
Refer 11ac PHY layer➤ for step by step description of each of the modules.

Similar posts on 802.11ac (WiFi 5)

This tutorial section on WLAN-11ac basics covers following sub topics:
Main page  frame  PHY layer  MAC layer  data rates  spectral mask  beamforming  radio planning


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11a WLAN Physical layer
11b WLAN Physical layer
11n WLAN Physical layer
WLAN 802.11-ac
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Difference between 11a,11b,11g,11n
Difference between 11-n,11-ac and 11-ad
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