## 3 Proposed VANET
### System Structure  
Figure 1 presents the proposed VANET network that deploys multiple technologies and interfaces to support heterogeneous vehicular applications. Heterogeneous wireless technologies can be used to build communication links between vehicles and RSUs. This kind of communication link is known for wireless access in the vehicular environment (WAVE). Passenger safety is verified with the help of WAVE communication. WAVE communication works to bring up-to-date information on vehicles and traffic flow. This offers a huge improvement in the competence of the management traffic system. The proposed VANET contains various entities, including OBU, RSU, and trusted authority (TA). Many applications that RSU accommodates aim to link with various network systems. OBU is available in every vehicle to gather helpful data about each vehicle, such as fuel, speed, acceleration, and other data. All information is then sent to any nearby vehicles with the help of the wireless network. The wired network is used to link between TA and RSU, knowing that all RSU are connected. TA is one of the main components of VANET, as it helps keep the VANET system working. Figure 2 presents the main components of the lower layer of the considered VANET. The main features of these components are summarized as follows:  
* RSU: RSU is situated in several locations along the roadsides. These locations include the parking regions or crossroads. This offers the vehicles domestic links for any crossing vehicles. The network devices inside the RSU depend on radio technology in IEEE 802.11P. This illustrates that these network devices are working to dedicate short  
Figure 1: End-to-end structure of the proposed VANET. range communication (DSRC). Besides this, RSU is useful to link different network systems with different network infrastructures;
* OBU: OBU is considered a global positioning system (GPS)-based tracking device available in each vehicle and offers vehicle data to transfer to RSU. Many electronic components are inside OBU, including IoT sensors, a resources command processor (RCP), an interface to users, and storage for read-write data to restore data. OBU's fundamental task is linking OBU with RSU or other OBUs. The radio transceiver of the OBU uses the IEEE 802.11p for wireless connection [36]. This connection with OBUs and RSUs takes place in message form. Furthermore, OBU gets its power from the vehicle's battery as well as the presence of several other components in each vehicle that work as an input for OBU, including the GPS, event data recorder (EDR), and forward and backward sensors;
* TA: TA's main duty is to control the VANET system, including the vehicle users, RSU, and OBU. It is also responsible for guaranteeing the VANET security administration. The proposed VANET deploys distributed edge computing at two tiers: fog computing (which represents the lower level) and MEC (which represents the higher level). Fog computing is considered an edge computing paradigm that helps the cloud computing network to enlarge its benefits and facilities among the network edges. It creates a link between the cloud and other smart devices that build all the links needed for the connection process. The difference between the cloud and the fog is that fog is assigned at the edges with less latency, while the cloud is more localized. Fog can send information, compute, save, stratify, and services for the end devices. VANET can meet its requirement by fog computing, for example, by decreasing the conjunction on the cloud and by fast reply to the important devices in addition to its capability to resolve the live data flow. The fog node can be represented in any device in the proposed VANET, including the infrastructure for roads and mobile vehicles. Each fog unit has all the facilities of network connections, stock, and computing units. The proposed VANET also deploys MEC nodes into two levels. The first level represents the vehicular MECs (V-MECs), which are MEC servers connected to RSUs.