Random-Padded OTFS Modulation for Joint Communication and Radar/Sensing Systems

This work presents a new random padded orthogonal time-frequency-space modulation (RP-OTFSM) for usage in joint radar-communication systems which is a modification of the zero-padded scheme (ZP-OTFSM). It is shown in the paper that exchanging in the delay-Doppler domain the impulse/Kronecker pilot surrounded by zero guard zone by random-value pilot with cyclic prefix does not cause any decrease of the transmission quality while offering increased efficiency of OTFSM-based radar systems. Such effect is got due to significantly lower level of side-lobes in the self ambiguity function (AF) of the transmitted signal as well as due to removing zero fragments from it. This feature is demonstrated through computer simulation of OTFSM-based transmission making use of the known ZP-OTFSM with an impulsive pilot and the proposed RP-OTFSM for standard ITU/ETSI EVA fading channel as well as for high-speed train (HST) channel. In both cases bit error rates (BER) are calculated and AF are computed.