An EMF-Aware Intelligent Framework for Adaptive SSB Periodicity Control in 5G Networks

Synchronization Signal Blocks (SSBs) support initial access, synchronization, and beam management in fifth-generation networks. However, the periodic transmission of SSBs contributes to background electromagnetic field (EMF) exposure, while increasing the SSB periodicity may increase the waiting time experienced by newly arriving User Equipment (UE). This paper proposes an EMF-aware adaptive SSB periodicity control framework that integrates Long Short-Term Memory (LSTM)-based demand prediction with a Proximal Policy Optimization (PPO) controller. Aggregated Internet usage measurements collected by Telecom Italia in Milan in 2013 at 10 min resolution are transformed into a traffic-derived UE arrival proxy. The LSTM model forecasts the proxy for the subsequent control interval, and the PPO policy selects a SSB periodicity from 5, 10, 20, 40, 80, and 160 ms. The optimization reward combines normalized SSB EMF power density and normalized aggregate UE waiting time, thereby avoiding dimensional and numerical-scale inconsistencies between the two objectives. The LSTM and PPO models are developed using six chronological weeks of data and evaluated without parameter updates over a seven-day held-out period. The prediction-driven controller achieves a mean SSB EMF power density of 3.67×10−5 W/m2 and a weekly average waiting time of 19.22 ms per person. Relative to the fixed 20 and 40 ms configurations, the proposed controller reduces mean EMF power density by approximately 65.4% and 30.8%, respectively. Its waiting time is close to that of the fixed 40 ms configuration and substantially lower than that of the fixed 80 ms configuration. Although the fixed 80 ms configuration provides lower EMF power density, it incurs considerably greater waiting time. The results show that the proposed framework provides an adaptive intermediate operating point between the lower waiting time of short fixed periodicities and the lower EMF exposure of long fixed periodicities.