  We address the challenge of developing an orthogonal time-frequency space
(OTFS)-based non-orthogonal multiple access (NOMA) system where each user is
modulated using orthogonal pulses in the delay Doppler domain. Building upon
the concept of the sufficient (bi)orthogonality train-pulse [1], we extend this
idea by introducing Hermite functions, known for their orthogonality
properties. Simulation results demonstrate that our proposed Hermite functions
outperform the traditional OTFS-NOMA schemes, including power-domain (PDM) NOMA
and code-domain (CDM) NOMA, in terms of bit error rate (BER) over a
high-mobility channel. The algorithm's complexity is minimal, primarily
involving the demodulation of OTFS. The spectrum efficiency of Hermite-based
OTFS-NOMA is K times that of OTFS-CDM-NOMA scheme, where K is the spreading
length of the NOMA waveform.
