## 1 Introduction  
VANET is a popular, modern network. The network is termed an ad-hoc network, as the position of the vehicles changes at every instant of time. The average speed of vehicular nodes varies from 40 to 80 km/h [1]. Due to this high randomness in location, VANET is quite prone to security threats, especially hybrid DoS attacks, including all forms of attacks. Uncertainties, such as hybrid DoS attacks, are the biggest reasons for security threats. VANET utilizes vehicles as mobile nodes in the form of a sub-class of a mobile ad-hoc network (MANET) to communicate with nearby vehicles and among vehicles close to roadside units (RSUs) or equipment, though is differs from other networks according to its characteristics [2]. Particularly, the vehicles (nodes) are inadequate for the road topology when moving; thus, vehicles' future positions can be predicted when information of the road is available. As per IEEE 1471-2000 and ISO/IEC 42010 framework general guidelines, VANET systems can be categorized into three domains, including mobile, infrastructure, and generic domains [3]. Figure 1 depicts the VANET infrastructure architecture (VIA). The mobile domain transfers the information and communicates with the infrastructure domain. It utilizes IEEE 802.11p beacons and signals, which process the data and proceed towards modulation [4]. Then, the infrastructure domain  
communicates with generic domains and then exchanges the information. The flows of data between the mobile and stationary resources results in effective utilization of the road with the user, which utilizes IEEE 802.11p beacon communication standard. In this research, the transmission rate of information for real-time IEEE 802.11p information delivery in VANET is 30 Mbps. Vehicles move in groups, as they are directed in the VIA to their intended destination (as shown in Figure 1). In the VIA also, vehicle cooperation in the group movement is such that they exchange frequent sporadic broadcasts of safety messages. These broadcasts carry the information of the speed of the vehicle and their position, whilst utilizing the IEEE 802.11p beacon's dedicated channel [5]. During normal operation of the IEEE 802.11p medium access control (MAC) protocol random access specification, beacon loss is possible. This can be attributed to impairment of wireless channels (i.e., beacon transmissions overlapping resulting from several vehicles, which can lead to collision/congestion). Collision/congestion (CC) can be reduced based upon proper selection of MAC protocol real-time transmission methods, which include secure authentication and key distribution algorithm models, and secure transmission range models, which can be deployed in the VIA network. Based upon this, performance parameters, such as real-time end-to-end delay sensitivity for trust enforcement of neighboring nodes in VANET, can be measured [6; 7]. Nevertheless, it is possible that the IEEE 802.11p beacon transmissions can also get corrupted through malicious attacker vehicles. They may also present themselves in all forms of attacks, including hybrid DoS attacks (HDSA), which include DoS jamming signal attack, (DoD JSA), packet drop (PD), and resources consumption/RSU or CPU overutilization (RCRCO) [8]. The VANET safety can seriously be at risk, since vehicles would not be capable of properly utilizing the information obtained. However, vehicles are required to utilize and transmit the information based upon the IEEE 802.11p beacon's relay through the RSU in order to sensitize awareness in VANET. The RSU utilizes the information to also update other vehicles about the requirements of end-to-end delay and jitter in the network, which  
Figure 1: The vehicular ad hoc network (VANET) Infrastructure Architecture (VIA). The mobile domain is composed of two parts. The infrastructure domain also consists of two parts. The generic domain has private and internet infrastructure. It can be defined in the form of varied nodes with servers and varied computing resources operating directly or indirectly for VANET.