# An Optimization Framework for Data Collection in Software Defined Vehicular Networks
## 2 Background and Literature Review  
A **Mobile Adhoc Network (MANET)** is an autonomous collection of mobile devices, such as smartphones, sensors, laptops, vehicles, etc., that communicate with each other over wireless links and cooperate with each other in a distributed manner to provide network functionality in the absence of fixed infrastructure [3]. These networks are characterized by self-organizing, dynamic, and volatile links between the wireless nodes and dynamic network topology [4]. Routing is challenging in MANETs due to the multi-hop network topology that can frequently change due to mobility [5]. Due to the mobility of the nodes, security vulnerabilities have arisen in MANETs such that attackers can eavesdrop, delete, modify, fabricate, and replicate protocol control packets or data packets more easily than wired networks [6]. Service and resource discovery are important aspects of MANETs, as they may have little or no knowledge of each other capabilities when there are no service or resource-discovery mechanisms [7]. As the mobile nodes of the MANET have limited energy, the energy efficiency of the network functions is very important [8]. A **vehicular adhoc network** is a subclass of MANET having no fixed infrastructure for communication and relying on vehicles themselves for network functionality [9]. A distinctive set of candidate applications such as collision warning and local traffic information for drivers, resources such as a licensed spectrum, rechargeable power source, and the environment having vehicular traffic flow patterns, privacy concerns, etc. distinctly identify VANETs from other MANETs [10]. Other distinct features which identify VANETs from MANETs are the high mobility of the nodes with dynamic network topology and the VANETs having an enormous number of nodes (vehicles) with high computational capacity [11]. VANETs are further characterized by the use of Dedicated Short Range Communication (DSRC), road-constrained mobility patterns, and not having significant power constraints [12]. A VANET works on the communication layer and plays a major role in future Intelligent Transportation Systems (ITS). In a VANET, each vehicle is identified as a node and equipped with an On-Board Unit (OBU), which is capable of exchanging information with other vehicles or Road Side Units (RSUs) [13]. RSUs are stationary communication nodes that are located near the roads in a VANET that enhances its connectivity [14]. Communication between vehicles is known as Vehicle to Vehicle (V2V) communication, while communication between vehicles and other infrastructure such as RSUs, tolls, internet access points, etc., is known as Vehicle to Infrastructure (V2I) communication [15]. Generally, V2X identifies the vehicle to everything communication. Sensors in vehicles and RSUs comprise a Vehicular Sensor Network (VSN) that can sense data related to traffic or environmental conditions, such as temperature, movement, pressure, vibration, etc., which are processed by vehicular applications and generate messages to be exchanged using the VANET [16]. Research and development in VANETs have dramatically increased due to the embracing of the IEEE 802.11p standard, which is a draft amendment to the IEEE 802.11 standard to add Wireless Access in Vehicular Environment (WAVE) for VANETs, and due to the licensed spectrum allocated for VANETs [17]. VANETs have applications in collision warning systems, optimal speed advising systems, driver assistance systems, entertainment, remote wireless diagnosis, etc. [18]. Privacy-preserving approaches are required for VANETs as the identifying information of vehicles, such as location, path, vehicle condition, etc., are exchanged in VANETs [19]. However, VANETs have their own set of challenges, such as high mobility of the nodes, security concerns, and routing issues [20].