What does “channel estimation” mean in the IQxel WLAN analysis?
Typical “real world” receivers use channel estimation methods to improve the receiver’s ability to accurately demodulate data. To help receivers perform this function the 802.11 standard defines specific “Training Fields” that are transmitted in the packets. The receiver pre-processes the received signal and removes components, such as frequency and phase shift, before attempting to demodulate data.
The IQxel has the ability to do similar pre-processing and you have options to choose frequency, phase, and/or amplitude correction. You also have the option to choose LTF (training field) or DATA (the complete packet) to use for the pre-processing estimation. The results you are seeing, a 2 dB improvement in EVM, seems about right for typical signal from a commercial device. Using all the correction methods and using complete DATA packet (not just the Training Field) will allow the most accurate estimation and give the best EVM results.