Pre EQ (802.11n/ac/ax/be)

The Pre EQ tracking algorithm tracks and removes phase noise before the equalizer.

Traditional single channel modulation always had the phase tracked after the equalizer. With multiple data streams, that may not be the best place to do it. If the phase noise is being generated by the receiver, there is now a mixture of phase noise generated by two oscillators. It is difficult to track well.

Typically, if the phase noise is primarily caused by the receiver rather than the transmitter, it's beneficial to select Pre EQ and do pilot tracking before the equalizer. If the phase noise primarily comes from the transmitter and the phase noise from the receiver is minimal, Post EQ is the best selection. Try both, look at the EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format. and use the one that gives the best result.

MIMO Multiple Input, Multiple Output: A physical layer (PHY) configuration in which both transmitter and receiver use multiple antennas. EQ on Pilot (802.11 n/ac only) - Variation of phase/amplitude/timing is calculated based on the difference between a pre-equalized pilot subcarrier and the ideal pilot multiplied with the MIMO channel. The MIMO channel on pilot subcarrier needs to be invertible for this setting to work correctly. Therefore, ideal pilots can be recovered through hard detection on MIMO equalized stream pilot, whether the pilot value on streams is the same or different.

Chan EQ on Pilot (802.11 n/ac only) - Variation of phase/amplitude/timing is calculated based on the difference between a pre-equalized pilot subcarrier and the common pilot multiplied with the composite MIMO channel . The value on the pilot subcarrier needs to be the same either in the preamble or data symbols over streams when using this selection. It doesn’t rely on the MIMO channel to be invertible. The composite MIMO channel is H’1 = H11 + H21 and H’2 = H21 + H22.