  This paper studies the low PAPR pilot design in delay-Doppler domain
modulation. We adopt a sequence based pilot design instead of the conventional
pulse pilot, to mitigate the PAPR issue. We develop simple channel estimation
algorithm composes of two-stages which are path identification and channel
coefficient estimation. The quantitative analysis on the channel estimation
error model is provided. Based on which the principle of pilot sequence design
in delay-Doppler domain is revealed. Experiment results shows that the proposed
scheme maintains a relatively low PAPR in time domain samples, while the
channel estimation performance approaches the ideal channel estimation in
limited-Doppler-Shift channel model.
