Flexible Intelligent Metasurfaces in High-Mobility MIMO Integrated Sensing and Communications

We propose a novel DD MIMO channel model incorporating FIM, which is suitable for ISAC in high-mobility scenarios. We then discuss how the proposed FPDD channel model can be applied in a logical manner to multicarrier waveforms that are known to perform well in DD environments, namely, OFDM, OTFS, and AFDM. Leveraging the proposed model, we formulate an achievable rate maximization problem with a strong sensing constraint for all the aforementioned waveforms, which we then solve via a gradient ascent algorithm with closed-form gradients presented as a bonus. Our numerical results indicate that the achievable rate is significantly impacted by the emerging FIM technology with careful parametrization essential in obtaining strong ISAC performance across all waveforms suitable to mitigating the effects of DD channels.