{"ID":5937053,"CreatedAt":"2026-07-07T03:14:33.014478982Z","UpdatedAt":"2026-07-09T14:01:10.825011661Z","DeletedAt":null,"paper_url":"https://arxiv.org/abs/2607.05119","arxiv_id":"2607.05119","title":"Multiuser MIMO-AFDM Beamforming for ISAC in Doubly Dispersive Channels","abstract":"Integrated sensing and communication (ISAC) in high-mobility channels requires waveform and beamforming designs that are robust to delay-Doppler dispersion. With this in mind, in this paper we study a monostatic multiuser multiple-input multiple-output (MIMO) affine frequency division multiplexing (AFDM) downlink system. We develop a discrete affine Fourier transform (DAFT)-domain model that preserves Doppler-induced inter-bin coupling and derive a data-aided delay-Doppler detector. The expected matched-bin detector signal-to-noise ratio (SNR) is shown to be proportional to a transmit-covariance beampattern, which leads to a detector-SNR-based sector-illumination constraint. The resulting sensing-constrained weighted sum-rate maximization problem is solved using a combined weighted minimum mean squared error (WMMSE) and majorization-minimization (MM) formulation. Simulations show that the proposed AFDM design outperforms its orthogonal frequency division multiplexing (OFDM) counterpart in terms of the rate-sensing tradeoff, robustness to Doppler, and delay-Doppler sensing quality.","short_abstract":"Integrated sensing and communication (ISAC) in high-mobility channels requires waveform and beamforming designs that are robust to delay-Doppler dispersion. With this in mind, in this paper we study a monostatic multiuser multiple-input multiple-output (MIMO) affine frequency division multiplexing (AFDM) downlink syste...","url_abs":"https://arxiv.org/abs/2607.05119","url_pdf":"https://arxiv.org/pdf/2607.05119v1","authors":"[\"Rang Liu\",\"Ming Li\",\"A. Lee Swindlehurst\",\"Norman Franchi\",\"Robert Schober\"]","published":"2026-07-06T14:07:17Z","proceeding":"eess.SP","tasks":"[\"eess.SP\"]","methods":"[]","has_code":false}