Performance Analysis of OTFS Modulation Scheme in Non-Terrestrial Communications

Orthogonal Time Frequency Space (OTFS) Modulation is a new technique in which information symbols are modulated in the delay-Doppler domain. The Doppler shift of time varying channels induces inter carrier interference in Orthogonal Frequency Division Multiplexing (OFDM) technique used in 4G and 5G systems. OTFS addresses the drawback of OFDM. In this work, the application of OTFS is considered for satellite communication. At first, OTFS and OFDM modulation techniques are briefly discussed. Next, OTFS is considered for satellite communication and different metrics-Bit Error Rate (BER) and capacity, are evaluated at Low Earth Orbit (LEO) satellite speed. The choice of OTFS transmitter parameters depends on the delay and Doppler shift of the channel and the requirement of the system. In OFDM, at satellite speed, Doppler pre-compensation is required to suppress ICI. The BER of OTFS is lower than OFDM at satellite speed, justifying its suitability in space communication systems.