# SURROGATES: Virtual OBUs to Foster 5G Vehicular Services
## 3 Architecture of the NFV-Powered Edge Computing Approach  
The main architecture of the SURROGATES solution is shown in Figure 1. As can be seen, the approach is to create virtual images of OBUs (i.e., vOBUs) as VNFs at the edge of the network, which can be based on road-side units, cellular base stations, WiFi access points, etc. These VNFs pre-process raw data from in-vehicle sensors that is sent through a monitoring middleware deployed in both the real OBU and the NFV-based one at the edge virtualization domain. Data to be collected from the OBUs consider navigation information, diagnosis and mechanical monitoring details of the car, and readings from other sensors connected to the OBU. Data analytics tasks envisaged at vOBUs include pre-processing, aggregation or pattern recognition involving individual vehicles, while global processing of data involving high-volume Big Data is performed at the cloud virtualization domain. Processed or cached information are accessed by vehicular services using vOBUs or the data analytics module. Hence, vOBUs act as computing offloading units for real OBUs and as a proxy in the downstream channel from services and users. This solves the issue of accessing the physical OBU from multiple services and requiring monitoring data when the OBU is temporally offline due to mobility issues.  
An OBU Manager module has been defined to be the initial contact point for physical OBUs wanting to connect to a virtual counterpart. This manager is also a VNF, and communicates with the MANO entity to indicate the need for a virtual OBU instance. The MANO entity offers the capabilities to manage all NFVs, and it provides the OBU manager the key function of scaling the system in the edge virtualization domain when new vehicles connect to the platform.  
The vehicle connectivity is managed by a hybrid approach with 802.11 OCB and 4G technologies, and using an IPv6-based network middleware based on our previous research [25]. In the multi-homed scenario considered, the OBU, which is in fact a mobile router, selects the most convenient interface, while, at the same time, seamless handovers are performed. This middleware allows the physical OBUs to connect to vOBUs, but also to the general Internet. Additionally, an in-vehicle wireless network is available for user devices potentially accessing services at the cloud virtualization domain.  
Message exchanges performed in the whole platform use Representational State Transfer (REST) protocols. Communications with the MANO entity use the Application Programming Interface (API) of the orchestrator. The virtualized infrastructure manager (VIM) used, which is detailed in the next section, allows the creation of different virtualization domains.  
It is important to note that the platform is open to any transport means. Although regular road vehicles allow the collection of many on-board sensors, our previous works note the potential of interconnecting two-wheelers in smart city and safety scenarios [10]. SURROGATES can both offload computing from OBUs and still present the vehicles as accessible continuously, distributing computation across access networks.  
Among the potential services to be implemented on the top of this architecture, the ones within the urban mobility field can exploit the MEC features specially. Pollution monitoring using clustering techniques, tracking and predictive diagnosis, congestion detection, or healthy mobility through urban areas can benefit from data pre-processing at vOBUs, alleviating growing computing loads at cloud data centers.