Next-generation vehicular networks are expected to provide the capability of
robust environmental sensing in addition to reliable communications to meet
intelligence requirements. A promising solution is the integrated sensing and
communication (ISAC) technology, which performs both functionalities using the
same spectrum and hardware resources. Most existing works on ISAC consider the
Orthogonal Frequency Division Multiplexing (OFDM) waveform. Nevertheless,
vehicle motion introduces Doppler shift, which breaks the subcarrier
orthogonality and leads to performance degradation. The recently proposed
Orthogonal Time Frequency Space (OTFS) modulation, which exploits various
advantages of Delay Doppler (DD) channels, has been shown to support reliable
communication in high-mobility scenarios. Moreover, the DD waveform can
directly interact with radar sensing parameters, which are actually delay and
Doppler shifts. This paper investigates the advantages of applying the DD
communication waveform to ISAC. Specifically, we first provide a comprehensive
overview of implementing DD communications, based on which several advantages
of DD-ISAC over OFDM-based ISAC are revealed, including transceiver designs and
the ambiguity function. Furthermore, a detailed performance comparison are
presented, where the target detection probability and the mean squared error
(MSE) performance are also studied. Finally, some challenges and opportunities
of DD-ISAC are also provided.Comment: Magazine paper submitted to IEE