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