# An Overview of Vehicular Communications
## 4 Vehicle-To-Everything  
The V2V and V2I communication models mentioned above are completed in the V2X, which represents a generalization. The latter consists in the data transfer from a vehicle to any entity that \begin{table}
\begin{tabular}{c c c} \hline \hline
**V2V Safety** & **Agency Data/Environment** & **Smart Roadside/Mobility** \\ \hline Emergency Electronic & Probe-based Pavement & Wireless Inspection \\ Brake Lights (EEBL) & Maintenance & \\ \hline Forward Collision & Probe-enabled Traffic & \\ Warning (FCW) & Monitoring & Smart Truck Parking \\ \hline Intersection Movement & Vehicle Classification-based & Intelligent Traffic Signal \\ Assist (IMA) & Traffic Studies & System (I-SIG) \\ \hline Left Turn Assist & CV-enabled Turning Movement & Signal Priority \\ (LTA) & \& Intersection Analysis & (transit, freight) \\ \hline Blind Spot/Lane & CV-enabled Origin-Destination & Cooperative Adaptive \\ Change Warning & Studies & Cruise Control (CACC) \\ \hline Curve Speed & Work Zone Traveler & Guidance for \\ Warning & Information & Emergency \\ \hline Do Not Pass & Dynamic Eco-Routing & Emergency Communications \\ Warning (DNPW) & (light, vehicle, transit, freight) & and Evacuation (EVAC) \\ \hline Vehicle Turning & Low Emissions Zone & Connection Protection \\ Right in Front of & Management & (T-CONNECT) \\ \hline Bus Warning & Eco-ICM Decision & Freight-Specific \\ (transit) & Support System & Dynamic Travel \\ \hline Queue Warning & Eco-Smart & Emergency Vehicle \\ (Q-WARN) & Parking & Preemption (PREEMPT) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Applications for connected vehicles. can influence it, or vice versa, and incorporates other more specific types of communication including Vehicle-to-Pedestrian (V2P) [50], Vehicle-to-Roadside (V2R) [51], Vehicle-to-Device (V2D) [52], and Vehicle-to-Grid (V2G) [53]. A broad representation of the V2V, V2I and V2X communications is shown in Figure 2. According to the report on the global state of road safety [54], there are about 1.25 million people died because of road accidents every year around the world. Almost half of the victims were identified as pedestrians, cyclists, and motorcyclists, defined collectively as Vulnerable Road Users (VRU) [55]. It is useful to note that the defects in road design and the lack of proper separation from traffic significantly affect the creation of an unsafe environment for drivers and pedestrians [56]. Another issue that should not be underestimated, especially in urban centers, is the distraction of pedestrians, caused by the use of their earphones and smartphones, frequently handled while walking down the street [57]. Therefore, it is necessary to develop a warning system also for pedestrians. One of the main purposes of the V2X technology is precisely to support the possible and efficient communication mechanisms between vehicles and pedestrians aimed at limiting accidents, sometimes fatal. Recently, in this direction, the Pedestrian Collision Warning (PCW) has been developed [58; 59], which can practice wireless modules included in mobile phones, such as Wi-Fi, Bluetooth, and Near Field Communication (NFC). In the detection system based on wireless modules included in the PCW architecture, for instance, as the Wi-Fi module competes, an active security mechanism for VRU, which uses beacon stuffing to alert pedestrians to imminent danger, has been introduced in [60]. The same module is employed in V2X communications, applying the Wi-Safe technology [61], but has a fundamental limit that is a unidirectional approach, where only pedestrians receive notices. On the contrary, Wi-Fi Direct [62], a peer-to-peer wireless standard that allows smartphones to communicate directly with each other rather than through an access point, as in cell phone towers, is practiced in [63]. However, Wi-Fi-based approaches have some drawbacks. First of all, a high power consumption, if using the Access Point/Client mode.