  In this study, we compare the single-carrier (SC) waveform adopted in IEEE
802.11ad and unique word discrete Fourier transform spread orthogonal frequency
division multiplexing (UW DFT-s-OFDM) waveform. We provide equivalent
representations of up-sampling and down-sampling operations of the SC waveform
by using discrete Fourier transform (DFT) and inverse DFT to enable explicit
comparison of these two similar waveforms. By using this representation, we
discuss why the IEEE 802.11ad SC waveform can cause suboptimal performance in
multipath channel and discuss how to improve it with UW DFT-s-OFDM. With
comprehensive link-level simulations, we show that replacing the 802.11ad SC
waveform with UW DFT-spread OFDM can result in 1 dB gain in peak throughput
without affecting the IEEE 802.11ad packet structure. We also evaluate the
cross links where the transmitter is UW-DFT-s-OFDM and the receiver is
traditional SC-FDE or vice versa. We demonstrate that UW DFT-s-OFDM receiver
can decode an IEEE 802.11ad SC waveform with a slight SNR loss while IEEE
802.11ad SC receiver can decode a UW DFT-spread OFDM waveform with an
interference floor.
