Weighted voting game based relay node management in vanets

In traditional Vehicular Ad Hoc Networks (VANETs) deployments, permanent and robust connection establishment to road side units (RSU) has arisen as a crucial problem. Here it is a known fact that, this challenge has been triggered by high mobility pattern of vehicles. To handle this problem, optimal relay vehicle selection can be seen as an efficient solution. To this end, in this work, we propose a novel optimal and fair relay vehicle selection algorithm based on weighted voting game. In our game theoretic approach, relay vehicle selections have been performed by various cooperative coalitions. Note that game theory is a perfect tool while designing such an algorithm as it is a formal applied mathematical tool to analyze and model complicated situations of interactive decision making. Our proposed weighted voting game algorithm can achieve fair and optimal results as well as increasing throughput and decreasing message transmission delay during packet dissemination as a result of using Banzhaf power measure. Performance evaluation results showed that compared to non-cooperative methods, throughput increases approximately by 24\% and message dissemination delay decreases by 18\%. This algorithm is repeated for various speed ranges. A general introduction and explanation of relay node management was presented in chapter 1. With recent advances in Information and communications technology VANET has become an important concept in order to provide an efficient and convenient road trips for drivers by obtaining required information along the road. Due to the mobile nature of vehicles that results in dynamic topological changes, establishing permanent and robust connection with road side units for maintaining connectivity has arisen as a challenging issue. To overcome these problems and for efficient management of optimal connectivity, it is essential to use some of the vehicles as a relay for compensation and reinforcement of connection. Providing a satisfying method for this selection is required and it is a challenging issue due to dynamic environment of roads. In literature survey part different methods of relay node selection is considered. In contribution section a brief introduction of proposed framework and algorithm has been given. In chapter 2, a detailed description of vehicular ad hoc networks is given. In this chapter the main purpose of using (VANET), and also their system components are discussed. Furthermore, a brief explanation of VANETs application is mentioned. The application of VANET varies from safety applications to traffic efficiency and infotainment applications. In addition, characteristic of VANETs which is an important factor of challenge recognition is considered. Different methods of communication pattern that is an inseparable part of every VANET is illustrated. Various type of routing protocols are also discussed. Game theory is a perfect tool while resolving some problematic situations. It is a formal applied mathematical tool to analyze and model complicated situations of interactive decision making. In chapter 3, the reason of game theory usage in this work is discussed. A general classification of games is shown. Voting game permits participants to come up with a common decision to choose the most eligible and suitable candidate. This method is used in this work for relay node selection and categorized. One type of voting game is called weighted voting game. Each player's weight doesn't represent the amount of power that player holds. For achieving fair results, there exist couple of power indices measures that are illustrated and explained in details. Banzhaf power measure is one of power indexes. It is defined by the probability of changing an outcome of a vote where voting rights are not equally divided among the voters. Players are free to enter and leave the coalitions. Therefore, because of mobile nature of vehicles we use this power index method. If one of the players changes its strategy and other players remain constant, the specific player can't acquire more benefits from that change in its strategy, this is called Nash equilibrium point. A brief definition of Nash Equilibrium that is the fundamental of each game is also given. Network architecture and system model is discussed and detailed in Chapter 4. The abstract network is shown. Anchor and Relay vehicle phrases are introduced. Moreover, an explanation of our proposed algorithm is given. A mapping between VANET elements for relay node selection and game theory is happened. Network topology examples and also proposed system model schema are shown. System model is consist of scanning, connection attempt, forming coalition, voting, optimal relay selection, and packet dissemination. Pay-off functions for both anchor and relay vehicles are calculated regarding to transmission probability of links between relay vehicle and RSU, available bandwidth of RSU, bandwidth characteristic of vehicle, and the cost of the service. Chapter 5, provided experimental results and performance evaluation. The performance of proposed cooperative weighted voting game algorithm is evaluated and compared with non-cooperative approach by using Matlab. Vehicles with 2 different speed ranges are examined by using this algorithm. Performance evaluation results showed that compared to the non-cooperative method increment in throughput results and decrement in message dissemination delay are achieved. In addition, a Realistic VANET Simulations is considered. A real world data is needed for realistic VANET simulations. Accumulating realistic data is required for this simulation. These information is processed using traffic generators. Realistic traffic generators are important to enhance the quality of VANET simulations. Usage of simple mobility models leads to optimistic communications. At the end, the conclusion part explains all the steps and methods. In this section a brief explanation of all the used methods are given.