## 5 Handover Scheme  
VANET consists of vehicles traveling along roads or streets. Its main purpose is to improve vehicles' safety, comfort, reliability, and security on the road. However, one of the most significant challenges in designing VANET is the issue of handover (HO), which arises when a vehicle goes from one network region featured by an RSU to another region encompassed by a different RSU. Achieving seamless HO in VANET is complex because of the high vehicle mobility and the limited coverage of RSUs, which do not have overlapping signals. 5G technology can help provide enhanced characteristics that are well-suited for real-time video streaming and can be utilized in designing effective solutions for the HO problem. Any system must include a handover method to facilitate the transfer of active communication management between RSUs. For example, let us assume vehicle A is traveling from the coverage region of RSU\({}_{2}\) to RSU\({}_{1}\), whereas vehicle B is moving between the coverage of RSU\({}_{1}\) to RSU\({}_{2}\). After the handover procedure is finished, RSU\({}_{1}\) takes charge of communication management for vehicle A, while RSU\({}_{2}\) acquires responsibility for vehicle B. Two main categories of handover methods exist: inter-RSU handover and intra-RSU transfer [38]. Inter-RSU handover refers to the process in which a vehicle moves from one RSU to another, requiring a smooth transfer of communication duties to ensure uninterrupted connectivity. In contrast, intra-RSU handover refers to the process of a vehicle transitioning between various types of connections inside the same coverage area of an RSU, such as switching from V2V communication to vehicle-to-RSU (V2R) communication. Both types of handover approaches are crucial for guaranteeing efficient and dependable communication management in dynamic vehicle networks. Inter-RSU handover in VANET can be classified based on several criteria, one of which is the classification of handover into soft or hard HO. In hard handover, the link to the previous RSU is disconnected before connecting to the incoming RSU, while in soft handover, the link to the incoming RSU is established before the disconnection of the previous RSU [39]. The handover process in an SDN vehicular network is more intricate than in conventional cellular networks. Initially, the radio resources may be renegotiated with a new SDN controller. Secondly, flow tables must be updated to reflect the topology. Third, live migration and service redirection are required if a MEC is present, which adds even more complexity to the handover process. Lastly, the generation of the handover for multi-hop links and MEC services will occur concurrently. Each of these elements increases the difficulty of handover. Trajectory prediction can be used to improve the handover process. This can assist in finishing flow table entry updates and service migration ahead of schedule. Learning-based methods are one way to tackle the problems of high mobility and handover. These techniques can be used to find possible trends that could lead to better load balancing and handover. For instance, reinforcement learning has been applied using base station context data such as vehicle speed, user count, and handover history. Similarly, online probabilistic neural networks have been proposed to use the mobility information of the vehicles to predict the next serving access point. However, the complexity of creating an appropriate objective that simultaneously maximizes the performance makes these machine-learning (ML) algorithms difficult to use, particularly when energy consumption needs to be considered. SDN prioritizes security and privacy because of the possibility of unauthorized access or false information causing catastrophic mishaps. Security mechanisms must perform real-time authentication to avoid traffic congestion that could hinder SDN operation [40]. Smooth vehicle HO is essential in a system designed with 5G-VANET to minimize user interruptions.