  Wireless channels generally exhibit dispersion in both time and frequency
domain, known as doubly selective or doubly dispersive channels. To combat the
delay spread effect, multicarrier modulation (MCM) such as orthogonal frequency
division multiplexing (OFDM) and its universal filtered variant (UF-OFDM) is
employed, leading to the simple per-subcarrier one tap equalization. The
time-varying nature of the channel, in particular, the
intra-multicarrier-symbol channel variation induces spectral broadening and
thus inter-carrier interference (ICI). Existing works address both effects
separately, focus on the one effect while ignoring the respective other. This
paper considers both effect simultaneously for cyclic prefix (CP)-, zero padded
(ZP)- and UF-based OFDM with simple one tap equalization, assuming a general
wireless channel model. For this general channel model, we show that the
independent (wide sense stationary uncorrelated scatter, WSSUS) selectivity in
time and frequency starts to intertwine in contrast to the ideal cases with
single selectivity. We derive signal-to-interference-plus-noise ratio (SINR) in
closed form for arbitrary system settings and channel parameters, e.g.,
bandwidth, delay- and Doppler-spread. With the SINR analysis, we compare the
three MCM schemes under different channel scenarios.
