Spatial-Frequency Correlation Design for Wideband XL-MIMO-Empowered ISAC Systems

The extremely large-scale multiple-input multiple-output (XL-MIMO) technology is emerging as a leading solution to meet the growing demands for high spatial resolution and spectral efficiency in future wireless networks. By examining the spatial correlation between received steering vectors and coherent processing gain vectors in wideband settings, we demonstrate how precise sensing and communication can be seamlessly integrated under a location division multiple access (LDMA) mechanism enabled by wideband XL-MIMO. Our theoretical analysis reveals the disparity between range and cross-range resolutions, emphasizing the critical role of wideband techniques in addressing the range resolution limitations of XL-MIMO systems. To mitigate this issue, we propose an efficient algorithm to optimize transmit precoding for both spatial and frequency beamforming. Supporting our findings, numerical and analytical results confirm the essential synergy between wideband technologies and XL-MIMO for achieving superior spatial resolution. Additionally, these advancements enable enhanced ISAC capabilities with expanded performance boundaries.