Exploring the Conditional Effect of RLF on Handover Failure Based on ns-3 Under Stochastic Channel Condition

A Key component of Handover failure (HOF) in Fifth generation (5G) cellular network is the underlying radio link failure (RLF) event; existing model based analyses of HOF have not adequately explored this dependency. Moreover, HOF as a function of user mobility necessitates models that incorporate spatio-temporal correlation that has been largely ignored. In this work, based on ns-3 simulation, we characterize the relationship between RLF and HOF considering the effects of handover parameters (i.e., hysteresis (Hys), time-to-trigger (TTT), A2 threshold, A4 threshold) and RLF parameters (i.e., out-of-synch threshold(Qout), out-of-synch indication (N310), insynch indication (N311) and RLF timer (T310)) for correlated RSRP samples. The study has been carried out for different kinds of handovers in Non-Standalone (NSA) deployment of 5G. Our study reveals that optimal settings of handover parameters and RLF parameters to optimize HOF are actually constrained by the correlation characteristics of the prevailing channels. Comparison of simulation results with an existing semi-analytic model based analysis shows thenoveltyof the proposed ns-3 simulation methodology in capturing the cumulative impact of all the aforementioned factors in causing HOF. This study will help the mobile operators in choosing optimal RLF and handover parameters tominimizeHOF under different UE velocities and fading scenarios.