# Slicing on the Road: Enabling the Automotive Vertical through 5G Network Softwarization
## 2 Background, Motivation, and Contributions
### Network Slicing for V2X Communications  
Addressing the demands of V2X applications entails a holistic approach that goes beyond the valuable ongoing effort of improving connectivity over the RAN. This is why the network slicing concept comes into the picture, with a solution that can potentially exhibit an end-to-end (E2E) scope encompassing both the RAN and the CN segments of a 5G system. Indeed, a slice can span all domains of the network: software modules running on cloud nodes, specific configurations of the transport  
Figure 1: The 5G service-based architecture. network supporting flexible placement/migration of functions, a dedicated radio configuration or even a specific Radio Access Technology (RAT), as well as configuration of the device. The potential of the network slicing concept for the vehicular environment and the need for _dedicated_ V2X slicing has been early unveiled in [6] and then further elaborated in [25], where a set of guidelines for the design of a network slicing V2X framework are dissected. Embracing the vision of V2X tailored slicing, in [4], 3 GPP mentions the usage of customized parameters identifying a slice for the automotive industry. More in detail, a specific _customized_ and _standardized_ Slice Service Type (SST) is proposed within the Network Slice Selection Assistance Information (NSSAI) parameters [23]. The SST refers to an expected network behavior in terms of features and services as requested by a given slice. The NSSAI also includes a Slice Differentiator (SD), that can help selecting among several network slice instances of the same type, e.g., to isolate the traffic related to different services provided over different slice instances. A standardized value could facilitate roaming support; it can be expected that vehicles move quickly and often cross over different countries/Public Land Mobile Networks (PLMNs) while connected to the network. The V2X umbrella term actually covers a multiplicity of use cases characterized by diverging service and connectivity requirements. Indeed, with the penetration of self-driving vehicles which require no human involvement, humans inside the vehicle will engage themselves in other more relaxing activities such as media consumption (e.g., web browsing or video streaming), reading, and sightsseeing. This feature would further suggest the design of customized network slices for different V2X services. The autonomous driving, tele-operated driving, vehicular infotainment, and vehicle remote diagnostics and management slices are proposed in [6]. Elaborating on the idea of different slices for different V2X services, the work in [26] focuses on the resource allocation, in the RAN only, for the autonomous driving slice and the infotainment slice as two sub-slices created on a common physical infrastructure to provide isolated services. The Road-side Unit (RSU) provides infotainment services only and decides which vehicle will act as a relay for the autonomous driving slice based on V2I and V2V link quality. These relays, acting as virtual Access Points (APs), are responsible for the reliable exchange of safety messages between vehicles of the autonomous driving slice. Further works analyze, at a high level, how to apply the network slicing concept to the V2X environment [27; 28]. To validate the theoretical design of network slicing solutions for V2X, experimental evaluations are important to shed light on their performance. Few field tests have been carried out thus far; for example, in November 2016, SKT and Ericsson jointly deployed network slicing on a 5G radio network infrastructure (operating on mmWave frequency bands) in a BMW car test track in South Korea [29]. Clearly, performing real car tests incurs high cost and entails legislation issues, while making hard the reproducibility of results. A simpler and cheaper playground can be very helpful to preliminarily investigate technical solutions before field tests, as targeted in this work.