Beyond Bandwidth: Phase-Coherent Distributed ISAC for 6G Positioning, Sensing, and Imaging

Presenter: Henk Wymeersch 

Committee: IEEE Communications Society (ComSoC) Signal Processing and Computing for Communications Technical Committee (SPCC-TC)

Abstract: High-resolution positioning and sensing have traditionally been driven by bandwidth. Many 6G deployments, however, will operate well below bandwidth-rich mmWave and sub-THz bands, making classical delay-resolution arguments insufficient. This talk presents a complementary approach: phase-coherent processing across a distributed infrastructure that creates a virtual aperture. Building on cell-free massive MIMO and distributed radar, we outline coherent multi-node fusion and its gains for localization accuracy, detection sensitivity, and imaging resolution in ISAC. We compare coherent and non-coherent fusion, identify regimes where each is preferable, and explain trade-offs among bandwidth, aperture, geometry, and coherence time. We conclude with key practical challenges (calibration, synchronization, modeling, and deployment optimization) and a roadmap toward robust phase-coherent ISAC in 6G.