Near-field delay-Doppler and spatial parameter coupling

Characterize near-field AFDM-enabled integrated sensing and communication by jointly resolving range, angle, and Doppler under spherical-wave propagation while exploiting AFDM’s delay-Doppler-domain structure.

Background

Near-field operation in extremely large-scale MIMO and high-frequency systems introduces spherical wavefronts and spatial nonstationarity, invalidating conventional planar-wave channel models. In dynamic environments, delay, Doppler, angle, and distance become coupled, so AFDM’s conventional delay-Doppler representation cannot be directly applied without new channel models, parameter-estimation methods, and waveform designs.

The unresolved issue is whether and how AFDM can retain its delay-Doppler advantages while simultaneously estimating the spatial and range-related parameters that arise in near-field propagation. The paper identifies this joint resolution problem as a basis for extending AFDM-enabled ISAC to large-aperture and high-carrier-frequency systems.

References

In particular, how to exploit AFDM's delay-Doppler-domain structure while jointly resolving range, angle, and Doppler in spherical-wave propagation remains largely unexplored.

— AFDM-Enabled ISAC in Dynamic Environments: Fundamentals, Technologies and Opportunities  (2609.04876 - Chen et al., 4 Sep 2026) in Section 6, subsection “Near-Field Coupling in AFDM-Enabled ISAC”