# Fog over Virtualized IoT: New Opportunity for Context-Aware Networked Applications and a Case Study
## 3 FDC over VFC Paradigm  
In this paper, a basic system model for VFC with multiple foglets (FIs) is illustrated in Figure 1. The current practice allocates mobile tasks to the closest FI. The model provides and operates multiple FIs. Moreover, we consider a case study and go in depth in the FDC as a vital component in VFC; we present a general resource allocation model and propose an adaptive scheduler which covers the hard limited QoSs. FC is a platform that uses a collaborative multitude of near-users edge devices [3] with some important characteristics shown in Table 1. FC provides data, computing, storage and application services [3,18] to end users [24]. An example scenario is shown in Figure 1. Specifically, in Figure 1, we adopt three main areas: vehicles area, RSU area, and FDC area [3,17,18].  
In the architecture presented in Figure 1, VFC provides a solid platform for applications used to provide services to users. VFC services are mainly implemented in Fog: these use a distributed architecture over moderate-bandwidth to provide high availability operations. As we see, vehicles are attached to one of the RSUs in the FN [12], with the heterogeneous type of devices considered as a physical infrastructure. Indeed, each FN consists of a single server or a set of servers that builds heterogeneous requests. On the other hand, vehicles are equipped with a smart device (e.g., smartphones) [7,17] that is wirelessly connected to the RSU. The mobile vehicles arbitrarily enter the field of the RSU and may leave its coverage area. FNs could be interconnected and each of them is linked to the FDC. Vehicles could request a service from the RSU (then transfer this request to the FN and finally the FDC to manage the request) while they freely move across the FDC and RSU areas and the FDC can provide them with the required services in order to facilitate the  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**FC** & **FDC** & \(\leftarrow\)**FN** & \(\leftarrow\)**RSU** & \(\leftarrow\)**Vehicles** \\ \hline
**Access Medium** & Fix Wireless & Fix Wireless & Wireless & Wireless \\
**Technologies** & & & WiFi/3G/4G-LTE & \\
**Mobility** & No & No & No & Yes \\
**Proximity** & Round & Near & Near & Nearly \\
**Connectivity** & Multi Hops & Multi Hops & Single Hop & Single Hop \\
**Geographic Distribution** & Low & Medium & High & Very High \\
**Heterogeneity** & No & Yes & Yes & Yes \\
**Architecture** & Centralized & Distributed & Distributed & Mobile \\
**Bandwidth** & High & High & High & Low \\
**Latency** & Low & Low & Low & Low \\
**Delay Jitter** & Low & Very Low & Very Low & Low \\
**Network Area** & Core & Edge & Field & Edge \\
**QoS** & Improve & High & High & High \\ \hline \hline \end{tabular}
\end{table}
Table 1: Main characteristics for vehicular Fog computing.  
Figure 1: The overall VFC architecture. CDC: Cloud-Data-Center with the main areas; FN: Fog-Node;  
RSU: Road-Side-Unit; Fl: Foglet; FDC: Fog-Data-Center.  
connectivity between service providers and users. Application services are provided for near-users that are located in this area (FDC area) as well as direct access to the context parameters with the main VFC characteristics shown in the Table 1. The management architecture of FNs should include challenge strategies for resource allocation, as well as the management of edge devices and computing and storage resources. Also, it is important to note that the architecture should be managed by Software Defined Networks (SDNs) [3] and Network Functions Virtualization (NFV) [24]. The correlated explanations are not within the scope of this paper. Motivated by these considerations, we aim to focus on the Fog computing environment and FDC component which are detailed in the next section.