Directional Downlink Sensing for Regional Monitoring: Enhancing Information Freshness

This letter investigates information freshness in downlink area sensing systems using the Age of Information (AoI) metric. By jointly considering the detection probability, arbitrary spatial distribution of targets, and radar scan period, we derive closed-form expressions for the average AoI. We further optimize the average AoI through appropriate beamwidth selection. Under certain conditions, the optimal beamwidth can be explicitly determined; otherwise, an efficient Initial-Point Optimized Projected Gradient Descent (IPO-PGD) algorithm is proposed. Numerical results validate both the accuracy of the theoretical analysis and the favorable performance of the proposed IPO-PGD algorithm.