Exploiting Phase Signatures for Delay Ambiguity Resolution in OTFS-based Sensing and Communication Systems

This paper proposes a method for resolving the delay ambiguity in orthogonal time frequency space (OTFS)-based sensing systems. In conventional OTFS-based sensing systems, the delay ambiguity occurs when the propagation delay from a target exceeds the delay period defined by the Zak transform. To address this problem, we exploit phase signatures by placing two pilot symbols at different Doppler bins in the transmitted signal and computing their phase difference from the received signal. Since the phase difference reflects how many times the propagation delay exceeds the delay period, we resolve the delay ambiguity by analyzing it. We evaluate the proposed method through the simulation of the OTFS-based sensing system under various signal-to-noise ratio (SNR) values in a single-target scenario. The result shows that the method resolves the delay ambiguity with 100% accuracy when the SNR exceeds 25 dB. These findings demonstrate that the proposed method provides a reliable and computationally efficient solution to the delay ambiguity in OTFS-based sensing systems.