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 OTFSMbased 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.