802.11ax Overview

The 802.11ax standard is a High Efficiency (HE) enhancement of the 802.11n-2009 standard (see 802.11n HT OFDM Overview) to improve data throughput capabilities of 802.11 wireless LANs and provide optimized support for multiple users, multiple data streams, and multiple environments.

802.11ax adds the following features:

additional signal bandwidths of 80 and 160 MHz Megahertz: A unit of frequency equal to one million hertz or cycles per second. (like 802.11ac)
an 80+80 MHz non-contiguous channel bandwidth mode (like 802.11ac)
1024-QAM Quadrature Amplitude Modulation modulation for data subcarriers
1x, 2x and 4x HE-LTF Long Training field duration modes

80+80 MHz Mode

The non-contiguous 80+80 MHz mode splits the signal into two separate 80 MHz bands which are not contiguous in frequency. For the purpose of transmitter testing, these two signals can be thought of as independent 80 MHz signals which can be demodulated separately (each 80 MHz signal contains enough information in the preamble for a receiver to demodulate it without even seeing the other 80 MHz signal).

This mode supports a 2-channel SISO measurement. It does not support a MIMO Multiple Input, Multiple Output: A physical layer (PHY) configuration in which both transmitter and receiver use multiple antennas. measurement.