Abstract
This paper proposes orthogonal time sequency multiplexing (OTSM),
a novel single carrier modulation scheme based on the well known
Walsh-Hadamard transform (WHT) combined with row-column interleaving,
and zero padding (ZP) between blocks in the time-domain. The information
symbols in OTSM are multiplexed in the delay and sequency domain using a
cascade of time-division and Walsh-Hadamard (sequency) multiplexing. By
using the WHT for transmission and reception, the modulation and
demodulation steps do not require any complex multiplications. We then
propose two low-complexity detectors: (i) a simpler non-iterative
detector based on a single tap minimum mean square time-frequency domain
equalizer and (ii) an iterative time-domain detector. We demonstrate,
via numerical simulations, that the proposed modulation scheme offers
high performance gains over orthogonal frequency division multiplexing
(OFDM) and exhibits the same performance of orthogonal time frequency
space (OTFS) modulation, but with lower complexity. In proposing OTSM,
along with simple detection schemes, we offer the lowest complexity
solution to achieving reliable communication in high mobility wireless
channels, as compared to the available schemes published so far in the
literature.