Evaluating Conditional handover for 5G networks with dynamic obstacles

Abstract

To enhance seamless connectivity in millimetre wave New Radio networks, Conditional handover has evolved as a promising solution. Unlike A3 handover where handover execution is certain after receiving handover command from the serving access network, in Conditional handover, handover execution is conditional on Reference signal received power measurements from current and target access networks, as well as on handover parameters such as preparation and execution offsets. Presence of dynamic obstacles may block the signal from serving and (or) target access networks, which results in violation of the conditions for handover preparation/execution. Moreover, signal blockage by dynamic obstacles may cause radio link failure, which may cause handover failure as well. Analytic evaluation of Conditional handover in the presence of dynamic obstacles is quite limited in the existing literature. In this work, handover performance of Conditional handover has been analysed in terms of handover latency, handover packet loss and handover failure probability. A Markov model accounting the effect of dynamic obstacles, handover parameters (e.g., execution offset, preparation offset, time-to-preparation and time-to-execution), user velocity and channel fading characteristics has been proposed to characterize handover failure. Results obtained from the proposed analytic model have been validated against simulation results. Our study reveals that optimal configuration of handover parameters is actually conditional on the presence of dynamic obstacles, user velocity and fading characteristics. This study will be helpful for the mobile operators to configure handover parameters for New Radio systems where dynamic obstacles are present.