Antenna Motion Mitigation and Clutter Removal for Sub-Millimeter Infrastructure Displacement Estimation Using Cellular Network-Based Radar

Bridges and transportation infrastructure face extreme environmental and physical stresses that accelerate deterioration, compromising their structural integrity. Structural Health Monitoring (SHM) traditionally relies on sensor networks, which can be costly and complex to maintain. This paper explores an alternative approach using existing sub-6G gNodeB Base Stations (gNB) to monitor infrastructure displacements, leveraging cellular networks' wide coverage and continuous operation. A key challenge is achieving sub-millimeter accuracy despite phase distortions from antenna motion due to wind. To address this, we propose an antenna motion estimation model based on stable target phase measurements, along with analytical and linear models to characterize and mitigate residual phase errors caused by static clutter. Simulations confirm the method's robustness, and its application to real-world data from a bridge in Nanjing, China, demonstrates reliable mitigation of phase residuals correlated with the antenna motion.