A Doppler-Aware RSRP Input Calibration Method for Handover in High-Speed Railway 5G-R

Short-term fluctuations in reference signal received power (RSRP) can repeatedly reset the time-to-trigger (TTT) timer and spatially disperse Event A3 handover triggers in high-speed railway 5G-R systems. This study presents a synchronization-aware, physically bounded calibration layer for the RSRP inputs supplied to the standard handover procedure. The method distinguishes the geometric inter-cell Doppler difference from the receiver-side residual frequency offset after synchronization and tracking. Doppler information is therefore used primarily as a physical prior for residual-frequency estimation and as the basis for a small, bounded useful-component correction, which is verified by direct CP-OFDM/FFT calculation. Geometry-based detrending, speed-adaptive causal residual smoothing with a persistent-attenuation guard, and a bounded position-difference prior are then applied without modifying HOM, TTT, Event A3, or RRC procedures. Event-driven Monte Carlo simulations use common random numbers and include propagation-model mismatch, localized blockage, and Doppler-observation-error tests. At 2.1 GHz, 350 km/h, and 30 kHz subcarrier spacing, the maximum serving-referenced Doppler-induced equivalent loss is 0.0294 dB. In the 2000-trial comparison at 350 km/h, the framework reduces the inter-cell RSRP-difference RMSE from 2.3449 to 1.9053 dB and the mean trigger-location error from 57.72 to 41.36 m. Relative to traditional Event A3, successful handovers increase from 1965/2000 (98.25%) to 1987/2000 (99.35%), RLF events decrease from 4/2000 (0.20%) to 1/2000 (0.05%), and ping-pong handovers decrease from 34/1965 (1.73%) to 19/1987 (0.96%). The results indicate that the principal benefit is improved spatial consistency of the handover trigger, while the other evaluated indicators are maintained or modestly improved. The dominant contribution arises from geometry-respecting residual smoothing and bounded position correction rather than Doppler power recovery. Field and broader multi-cell validation remain necessary.