DOA Estimation via Space-Time-Coding Metasurface with Nonuniform Arrangement

To address the issues of large volume and high hardware costs in traditional antenna arrays when estimating the direction of arrival (DOA), we innovatively utilize programmable metasurfaces to replace conventional array architecture and achieve dynamic control of spatial electromagnetic waves through their reconfigurable electromagnetic properties. To tackle the significant decline in estimation accuracy of the traditional phase interferometer method under low signal-to-noise ratio (SNR) conditions, we adopt the method of space-time coding modulation (STCM) and directly solve the DOA estimation value by using the analytical relationship between the steering vector and the modulation matrix. Furthermore, to significantly improve the estimation accuracy, we strategically nonuniformly position the metasurface units to augment the array aperture. The simulation experiments have validated the robustness and superiority of the NSTCM method in low SNR environments.