  Orthogonal time frequency space (OTFS) modulation is a recently proposed
waveform for reliable communication in high-speed vehicular communication
scenarios. It has better resilience to inter-carrier interference (ICI) than
orthogonal frequency division multiplexing (OFDM). In this work, we describe
OTFS as block-OFDM with a cyclic prefix and time interleaving. This
interpretation helps one visualize OTFS in the light of OFDM as well as it also
helps in analyzing the gain obtained by OTFS over OFDM. Further, we compare the
performance of OTFS with its contender 5G new radio (NR)'s OFDM configuration
of variable subcarrier bandwidth (VSB-OFDM) while considering practical forward
error correction codes and 3GPP high-speed channel model. This provides
realistic performance comparison, which is highly desired for technology
realization. Considering practical channel estimation, we find that OTFS
outperforms VSB-OFDM with 5G NR parameter by about 5dB. We also present results
on peak to average power ratio (PAPR) due to specific pilot structure used in
OTFS for channel estimation.
