# SURROGATES: Virtual OBUs to Foster 5G Vehicular Services
## 1 Introduction  
In vehicular scenarios, on-board units (OBU) have evolved from specific purpose units designed for telematic services, such as fleet management or road tolling, to generic networked nodes capable of interconnecting other in-vehicle devices, acting as mobile routers. These units can maintain connectivity with the infrastructure (Vehicle-to-Infrastructure, V2I) or other vehicles (Vehicle-to-Vehicle, V2V) using wireless communications, and the access to in-vehicle sensor data is becoming of paramount importance in Smart City scenarios, where the vehicle will be considered another (mobile) sensor [1]  
The arrival of 5G technologies will complement already available communication technologies, such as 4G or IEEE 802.11 running Outside the Context of a Basic Service Set (OCB), formerly known as 802.11p. Virtualization, network orchestration, and multi-access edge computing (MEC) are novel strategies that can provide great benefits for Cooperative Intelligent Transportation Systems (C-ITS) [2]. Virtualization of network and computing nodes is a reality in cloud deployments, and it is expandingto the edge of the access network in designs involving MEC-based configurations, where processing is moved from the final devices and, partially, from cloud nodes to an intermediate layer near the access network. Next-generation vehicular services, such as the ones in the area of urban mobility and, in general, those interconnecting on-board sensors, require continuous data gathering and processing, but current architectures in the field are stratified in two-tier solutions in which data is collected by OBUs and sent to cloud servers. As initially stated in [3], intermediate cache and processing layers following fog/edge computing principles would be highly beneficial for covering data sensing needs from vehicles in scenarios of smart cities/roads. The MEC paradigm can further extend this capability in V2I data flows, by taking advantage of the communication path through the access network in order to move such computing near the end-devices. This scenario presents a good frame to offload data analytics tasks from OBUs, which should focus on actions of higher priority such as maintaining vehicle connectivity, managing communication flows, or applying security measures to data traffic. The migration of processing tasks to the network as virtual network functions (VNFs) is not direct, and a proper management plane should be integrated, above all in dynamic scenarios as the vehicular one. In this line, management and orchestration facilities (MANO) are becoming popular to dictate the operation of virtualized infrastructures. In the C-ITS domain, virtualized functions should be instantiated on-demand and an efficient real-time management of resources should be provided. These strategies closely follow the precepts defined for the upcoming 5G architectures. Therefore, the flexible management of network and processing resources in 5G will be greatly exploited in the vehicular ecosystem [4]. One of the most important markets within the commonly known as \"connected car\" field is monitoring of vehicle vital signs, which will be the seed of many services. This is basically the extraction of on-board sensor data but requires a proper support of a V2I network dealing with vehicle communication flows. Although initial approximations in the area of fleet management were exclusively based on 2.5 G cellular networks, soon new approaches appeared exploiting the advances of new 3G/4G technologies together with vehicular ad hoc networks (VANETs) [5]. These hybrid solutions could group vehicles in clusters and select a representative proxy to communicate with the Internet. This reduced data exchange with potentially congested 3G base stations, by aggregating and compressing monitoring data [6].