Time-Or Frequency-Domain Equalization for Wideband OFDM Channels?
OFDM suffers from inter-carrier interferences in the presence of the time variation. This paper seeks to quantify the amount of interferences resulting from wideband channels which assumed to follow the Multi-Scale/Multi-Lag (MSML) model. Due to the fact that the mobility in wideband channels induces scale effects, Doppler is revealed in a manner distinct from the frequency shifts experienced in narrowband systems. The MSML channel model results in full channel matrices both in the frequency and time domains. However, banded approximations are still possible, leading to significant reduction in the equalization complexity. Herein, measures for determining whether time-domain or frequency-domain should be undertaken are provided based on the amount of the resulting interference.