# Intelligent Handover Decision-Making for Vehicle-to-Everything (V2X) 5G Networks
###### Abstract
These advancements are driven by the new capabilities of 5G networks, including slicing, edge computing, and high mobility users, with the aim of optimizing user experience and ensuring effective utilization of network resources. UEs in cellular networks seamlessly transfer their connections from one cell to another during an active call or data connection by transferring an active communication session using the handover (HO) procedure. An HO is initially triggered by the UE in response to low signal strength from the serving cell, requested by the serving cell, or at regular intervals [6]. This process usually results in frequent and high-volume connection disturbances and reconnections, especially when a UE moves close to the network edge and HOs are triggered in brief time intervals [7]. HOs can be classified into various types. Intra-frequency HOs occur at serving \begin{table}
\begin{tabular}{c c} \hline
**DSRC (Dedicated Short Range Communication)** & **C-V2X (Cellular-V2X)** \\ \hline Released in 2010 and deployed in 2017. & Deployed for LTE direct C-V2X in 2016, and indirect-V2X in 2024. \\ \hline Standardized by IEEE 802.11p and IEEE 802.11 bd. & Defined by 3 GPPP \\ \hline Primarily operates in the 5.9 GHz band & Can operate in the 5.9 GHz band and in operator-licensed band. \\ \hline Supports Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communications. & Supports inter-vehicle (V2V), pedestrian (V2P, infrastructure (V2I), and network (V2N) communications. \\ \hline \end{tabular}
\end{table} 
Table 1: V2X access technologies. and target stations that operate at the same carrier frequency, whereas inter-frequency HOs occur at serving and target stations that operate on different carrier frequencies. In heterogeneous networks (HetNets), the capacity requirements are fulfilled by creating multiple cellular layers. An intra-layer HO is performed among cells of various sizes based on the received signal strength/quality from cells of similar layers. A cell from a certain layer can allow a UE to offload to a small cell, resulting in an inter-layer HO. HOs can also use the same Radio Access Technology (RAT), called Intra-RAT HOs, while vertical HOs occurring between different RATs are referred to as Inter-RAT HOs. HOs that occur among various systems and technologies under the same operator are called Inter-Operator HOs, whereas HOs that occur between different operators, such as during roaming, are called Intra-Operator HOs. HOs can also be categorized based on interfaces: Xn-based handover management and NG-based interfaces. Xn-based handover management uses the Xn interface between base stations without dealing with the core network, whereas the NG-based interface sends control messages to the network functions in the core network. X2/Xn interface-based handovers are six times faster than network-based handovers as the core network signaling load is reduced [6]. Performance reporting criteria can be event-triggered, periodic, or on-demand/blind [8]. HO actions are performed based on factors such as serving cell signal-level reduction, load balancing, and high error rates. Once these factors reach unacceptable levels, a UE connection must be transferred to a suitable, reliable, and stable cell to ensure seamless connectivity. This process, although occurring at a high frequency, can be challenging, especially for high-speed UEs such as drones [8]. High-speed UEs in V2X networks frequently move in and out of coverage areas, often from one network to another. This triggers frequent changes in the connection factors that necessitate HOs. A test conducted by 3 GPP in 2013 to evaluate HO performance in a UDN showed that the number of handovers increased by 17% for HetNets compared to the macro-cell network alone [9]. Although the suggested solution is that an HO scheme for heterogeneous vehicular networks with varying access technologies is necessary for a smooth handover [10], the deployment of mmWave in 5G would create more issues in this regard because the coverage areas will be smaller [11].