Windowing & OFDM

Post date: Jun 06, 2015 10:21:33 PM

It is worth noting that if the oversampling of the signal (i.e, larger IDFT size than the utilized subcarriers) or interpolation are not taken into account, the adjacent channel interference (ACI) in the out-band region will solely depend on the performance of image rejection filter and DAC characteristics, rather than the windowing method. This is simply because of the fact that Fourier transformation of discrete samples is periodic in frequency. Therefore, the major problem would be the images, i.e., the signal itself. However, when we consider the oversampling or interpolation, the windowing operation will be helpful to mitigate ACI beside image rejection filter.

On the other hand, if we consider the leakage in-band region, this time, the image rejection filter may not be useful and a windowing operation mitigates the leaked power without a complex implementation.