Complex sentence: The "x" "N" summation is mathematically equivalent to aliasing, leading to decimation in frequency, leaving only DTFT samples least affected by spectral leakage, which is usually a priority when implementing an FFT filter-bank (channelizer).
Split into simpler sentences: The "x" "N" summation is mathematically equivalent to aliasing, leading to decimation in frequency, leaving only DTFT samples least affected by spectral leakage. That is usually a priority when implementing an FFT filter-bank (channelizer).