Early-Scheduled Handover Preparation in 5G NR Millimeter-Wave Systems

TL;DR

This paper identifies a new early trigger for HO preparation and demonstrates how it can beneficially reduce the required time for HO execution reducing channel quality degradation and enable a new HO preparation scheme that offers a novel, user-aware, and proactive HO decision making in MIMO scenarios incorporating mobility.

Abstract

The handover (HO) procedure is one of the most critical functions in a cellular network driven by measurements of the user channel of the serving and neighboring cells. The success rate of the entire HO procedure is significantly affected by the preparation stage. As massive Multiple-Input Multiple-Output (MIMO) systems with large antenna arrays allow resolving finer details of channel behavior, we investigate how machine learning can be applied to time series data of beam measurements in the Fifth Generation (5G) New Radio (NR) system to improve the HO procedure. This paper introduces the Early-Scheduled Handover Preparation scheme designed to enhance the robustness and efficiency of the HO procedure, particularly in scenarios involving high mobility and dense small cell deployments. Early-Scheduled Handover Preparation focuses on optimizing the timing of the HO preparation phase by leveraging machine learning techniques to predict the earliest possible trigger points for HO events. We identify a new early trigger for HO preparation and demonstrate how it can beneficially reduce the required time for HO execution reducing channel quality degradation. These insights enable a new HO preparation scheme that offers a novel, user-aware, and proactive HO decision making in MIMO scenarios incorporating mobility.

Figures (14)

• Figure 1: Interplay between UE and NW during the handover HO preparation phase.
• Figure 2: A3 Event. The quality of neighboring cells exceeds the quality of the serving cell by an offset value. A3 event entry criterion fulfillment (T0) throughout the TTT duration (A3).
• Figure 3: A5 Event. Only when both entry criteria are satisfied, the UE reports event A5 to gNB.
• Figure 4: Top view of random individual trajectories generated by five distinct users (a), 5G NR site deployment with the base station located at the corners of three adjacent cell sites, each shaped as a hexagon and depicted in dark blue (b). Users move along individually randomized circular trajectories at constant velocities of 25 m/s (v1) or 31 m/s (v2).
• Figure 5: 2D projection of RSRP distribution generated by the 4x3 SSB wide beam pattern.