When estimating the channel impulse response (CIR) using FFT-based correlation vs. xcorr() in MATLAB, I notice that while the main peak aligns well, the amplitudes of MPCs differ.
What could explain this amplitude mismatch? Which method should be trusted more for accurate CIR amplitude estimation: xcorr() or FFT-based?
Thank you!
The amplitude mismatch between FFT-based CIR estimation and MATLAB's xcorr() comes from linear vs. circular correlation and normalization differences. xcorr() gives accurate linear correlation by default, while FFT assumes circular correlation, causing errors unless you zero-pad signals to at least Lx + Ly - 1. Also, xcorr() has clear normalization options, but FFT needs manual scaling. xcorr() is more reliable out-of-the-box; FFT is faster but needs careful setup for accuracy.
Thank you, Mohammad Nikbakhtbideh for the answer. I appreciate it.
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