# Slicing on the Road: Enabling the Automotive Vertical through 5G Network Softwarization
## 3 5G-V2X Network Slicing Architecture
### Architecture Components  
The three layers of the high-level architecture and the relevant components are illustrated in Figure 2 and briefly discussed in the following. The Infrastructure layer includes RAN nodes and devices, MEC servers, and the Transport network. * RAN Nodes and devices. Heterogeneous RAN technologies characterize the V2X scenario, including Wi-Fi APs, RSUs, and eNodeBs. We consider all network devices as SDN-enabled switches managed by SDN controllers. * MEC servers. They host network functionalities and applications that require ultra-low latency access. We refer to the European Telecommunications Standards Institute (ETSI) framework, as a reference for their deployment [33]. There, the MEC server is referred to as Multi-access Edge (ME) host [33]. It is an entity that contains the ME platform and a virtualization infrastructure which provides compute, storage, and network resources for the ME applications. The latter are \begin{table}
\begin{tabular}{c c} \hline
**Requirements/Features** & **Enablers** \\ \hline Multiple slices/sub-slices activation & NSSAI with SST and SD plus additional parameters (e.g., Device type) \\ \hline \multirow{2}{*}{Multi-tenancy management} & Flexible slice template and description for different automotive verticals (e.g., road authorities, car manufacturers) \\ \hline Massive communications & Multiple AMF instances to manage the signaling load due to mobility \\ \hline \multirow{2}{*}{Intra-operator mobility} & Slice reconfiguration; MEC-assisted \\  & service migration; mobility prediction mechanisms \\ \hline \multirow{2}{*}{Inter-operator mobility} & Basic set of functionalities for V2X slices agreed among all operators; \\  & unlicensed bandwidth for V2V communications in absence of infrastructure \\ \hline \end{tabular}
\end{table} 
Table 1: Requirements and enablers for V2X network slicing. running, e.g., as virtual machines (VMs) or containers, on top of the virtualization infrastructure provided by the ME host. They can interact with the ME platform to consume and offer ME services. To match the requirements of delay-critical and/or bandwidth-demanding V2X slices, we propose to deploy the V2X AS, normally placed in remote clouds, as an ME application running in the ME host. The ME services Radio Network Information Service (RNIS) and Location Service (LS), envisioned by ETSI [33] (see Figure 3, right), can also play a role for V2X slicing by providing radio-related information, i.e., low-level signaling, helpful to provide radio-related augmented services and to determine the location of a connected device. * Transport Network. The SDN-enabled transport network interconnects CP and UP Virtual NFs (VNFs) and Physical NFs (PNFs), in the RAN and CN, among each other and with external data networks. SDN is used to steer traffic between NFs of a given slice through the set-up of paths that can be automatically reconfigured either to handle traffic engineering requirements or to react to possible network failures and changing conditions (e.g., mobility). The Service layer hosts the 5G network functions [23], which can be PNFs or VNFs deployed by the operator and/or by a third party to enforce a given network behavior in the slice. Following NFV principles, UP and CP functionalities of different slices and be independently scaled and displaced in convenient locations and then chained through SDN to flexibly support various and novel services. The Business layer resides at the top of the model and includes services and use cases of the vertical markets for which slices are designed. It encompasses the mechanisms and tools to describe the slice behavior at a high level, and to capture the requirements of a given Service Level Agreement (SLA) for a vertical segment, whose assurance is tracked by the Operation Support System (OSS)/Business Support System (BSS). Such a description needs to be then translated to the underlying layers.