Covert Performance Analysis for OTFS Frame Structure Against Sequential Change-Point Detection

Covert communication aims to hide the existence of wireless transmissions which provides a strong security guarantee for wireless networks. This paper investigates the covert communacation performance of Orthogonal Time Frequency Space (OTFS) frame. The transmitter transmits messages to the receiver through OTFS modulation, where an eveasdropper tries to detect its existence. Different from the binary hypothesis test based the radio meter detection framework considered in prior works, we adopted sequential change-point detection (SCPD) framework and derives the closed-form expression for the average run length ratio (ARLR). In simulation results, we analyze the conditional average detection delay (CADD) reflecting the covert communication performance for the OTFS frame structure on the covert performance. Our results indicate that the closer the guard interval position is to the detection start position, the better the covert performance can achieve, while the pilot has the opposite effect.