Comparison of DFT and cosine modulated filter banks in multicarrier modulation

This paper examines the comparative performance of DFT and cosine modulated filter banks used in multicarrier signaling over a linearly distorted channel, affected by both white Gaussian and NEXT noise. The interference caused by the overlap in the frequency responses of the signaling filters is calculated analytically and simulation results are given to support the theoretical calculations. It is shown that without any pre-receiver processing, the level of interchannel interference is lower in the cosine-modulated family of filters, because of their higher stopband attenuation. We also examine how pre-receiver processing (short equalizer plus cyclic prefix) can lower the level of interference, especially in the DFT system. Finally the capacity of a sample channel, similar to the twisted-pair channel of a subscriber loop, is calculated with and without the effect of interference taken into consideration.