# An Effective and Efficient Adaptive Probability Data Dissemination Protocol in VANET
## 1 Introduction  
A vehicular ad hoc network (VANET) consist of moving vehicles connected via wireless technology e.g., Wireless Access in Vehicular Environment (WAVE) for the aim of exchanging information. The vehicles are considered as \"nodes\" within a network [1]. VANET is the subclass of the mobile ad hoc network (MANET), and the difference between them is that MANET is mobile-based whereas VANET is not. Since the movement of vehicles in VANETs is of varied speed, the design of the data dissemination protocol is considered an important aspect in this field of researches. The primary goal of VANET is to increase the safety of the passengers. Communication in VANET involves vehicles and other infrastructure along the roads designated as the \"on board units\" (OBUs) and \"roadside unit\" (RSU), respectively. These units are hardware devices that ease the exchange of data within the vehicular environment. Communication among the hardware's can be classified into three categories as depicted in Figure 1. Vehicle-to-vehicle (V2V), this communication involves vehicles directly communicating with each other without depending on other infrastructure. The purpose of V2V is to support the data dissemination application relying on the application of the IEEE 802.11p standard [2]. The vehicle-to-infrastructure (V2I) includesvehicles communicating with roadside infrastructures for the purpose of collecting and gathering data. The hybrid architecture is the combination of both V2V and V2I whereby vehicles and roadside infrastructures communicate with each other in different ways depending on the distance parameters. The main challenge is a high number of vehicles moving with high speed, and therefore it takes a short period of time for reliable exchange of data within a network (connectivity problem). Another challenge faced in this technology is the restriction of road structure and traffic issues in the vehicular environment. Such activities often bring new challenges in VANET. Hence the study of data dissemination in VANET should be taken into consideration. Many researchers have specified two types of VANET application such as the safety and no-safety applications. However, the most important is safety application since it plays a significant role in reducing the number of accidents as the major goal of design VANET [3]. This application gives the driver an early warning (alert message) of an accident that has occurred. This helps to prevent accidents by giving the drivers extra time to react. Nevertheless, the VANET application can use the available network resources such as bandwidth to supply other services (non-safety application). The safety application includes valuable information, advertisements, and entertainment. The role of this application is to comfort the passengers and provide other applications such as parking availability services, and internet connectivity [4]. The entertainment application like sharing movies, music, chatting with each other during their long journey is not linked to the safety application. The data dissemination process in V2V depends on the application of IEEE 802.11p standard [2]. This vehicular environment can tolerate limited network bandwidth, thus the bandwidth of 10 MHz is divided into six service channels (SCH) as well as one control channel (CCH) CCH is designed to provide safety applications only in a vehicular environment. The design of the data dissemination protocol should fit the different requirements of various VANET applications such as improve reliability, decrease dissemination delay time and increase the packet delivery ration [5; 6; 7; 8]. Many broadcast techniques especially traditional ones such as blind flooding originate from the \"broadcast storm problem\" [9]. This happens when every node within a network area must rebroadcast a packet immediately after receiving the message to ensure the message is delivered to distant vehicles in the network. By doing so, a large amount of duplicated messages are disseminated.