This white paper aims to briefly describe a proposed article that will
provide a thorough comparative study of waveforms designed to exploit the
features of doubly-dispersive channels arising in heterogeneous high-mobility
scenarios as expected in the beyond fifth generation (B5G) and sixth generation
(6G), in relation to their suitability to integrated sensing and communications
(ISAC) systems. In particular, the full article will compare the
well-established delay-Doppler domain-based orthognal time frequency space
(OTFS) and the recently proposed chirp domain-based affine frequency division
multiplexing (AFDM) waveforms. Both these waveforms are designed based on a
full delay- Doppler representation of the time variant (TV) multipath channel,
yielding not only robustness and orthogonality of information symbols in
high-mobility scenarios, but also a beneficial implication for environment
target detection through the inherent capability of estimating the path delay
and Doppler shifts, which are standard radar parameters. These modulation
schemes are distinct candidates for ISAC in B5G/6G systems, such that a
thorough study of their advantages, shortcomings, implications to signal
processing, and performance of communication and sensing functions are well in
order. In light of the above, a sample of the intended contribution (Special
Issue paper) is provided below