Sharif Digital Repository

Mobile ad hoc networks have been attracted the attention of many researchers during last years. One of the major concerns faces such networks is the security issue. The root of this concern is the fact that the intermediate nodes have the responsibility of packet transportation and forwarding. The nodes inside the mobile ad hoc networks assumed to be trusty while they can read, change or drop the transported packets. Cryptography as the cornerstone of the security could be play an essential role in such networks. Any cryptosystem need some keys to be able to secure communications. In large scale mobile ad hoc networks storing the whole keys in all nodes is inefficient, if possible, due to... 

Mobile ad hoc networks (MANETs) are the dynamically reconfigurable wireless networks in which mobile nodes communicate with each other without the need for any fixed infrastructure. In these networks mobile nodes are free to move, therefore, network topology changes rapidly. These changes can lead to significant performance degradations in network protocols. To cope with this, a desired solution is to predict movements of mobile nodes. In this way, we can be prepared for changes. This thesis proposes two mobility prediction methods. In both methods, each node uses the information extracted from its own history of movements to predict its future location. Results obtained by applying two... 

Delay Tolerant Networks are a variation of Mobile Ad Hoc Networks, in which low density of nodes in the network area results in global disconnectivity among the nodes. In these networks, communication of data throughout the networks takes place by the means of mobility; nodes store data packets and carry them around the network and forward them to other nodes they encounter along the way. In these situations, a proper selection of data to be exchanged between nodes has a great impact on the quality of data distribution in the whole networks. There is a common assumption among most of the techniques presented in category of Delay Tolerant Networks. They assume the probability of more than two... 

In recent decades, Securing mobile ad hoc networks has attracted much attention. Today, several security tools, such as intrusion detection systems are used in the network. Methods based IDS works on pattern recognition and anomaly detection are divided into two categories. Pattern recognition methods based on known attack patterns work with high detection rate, but do not have the ability to detect new attacks. Anomaly detection techniques have the ability to detect new attacks, but they have high false alarm rate.
In this thesis, an anomaly detection system based on artificial immune designed, implemented and evaluated.For example, an anomaly detection methods such cases, a variety of... 

Due to popularity of mobile wireless devices, security of mobile ad hoc networks (MANETs) being more important than before. Traditional key management schemes based on symmetric key cryptography are became ineffective because of dynamic and infrastructureless nature of these networks.Recent studies are mainly based on traditional public key cryptography schemes and ID-based cryptography schemes. On the other hand, Contributory schemes seem suitable for MANETs because of their inherent self-organize property. Key update and Key revocation are the fundamental issues of key management schemes in mobile ad hoc networks. Certificateless public key cryptography, in addition to solve those issues,... 

Mobility is one of the most challenging issues in mobile Ad-Hoc networks which has a significant impact on performance of network protocols. To cope with this issue, the protocol designers should be able to analyze the movement of mobile nodes in a particular wireless network. In this thesis, a new framework called Mobility Analyzer has been proposed. At first, Mobility Analyzer categorizes mobility models based on their mobility characteristics; subsequently, it uses mobility metrics for evaluating mobility traces which are collected by GPS or generated by mobility simulators. Finally, Mobility Analyzer recognizes the mobility model of mobility traces based on mobility metrics and measures... 

Along with the huge applications of wireless networks and creation of advanced wireless technologies, such as Bluetooth, WiFi, 3G and 4G, an evolution of Mobile Ad Hoc Networks emerged called opportunistic networks. In these networks, network topology is unpredictable; therefore, to send the message to the destination, moving nodes were used opportunistically. So one of the main challenges in this type of network is the routing problem. Amongst existing methods, methods that apply context information can help greatly to choose the right path. In this thesis a method was presented to gather information applying cell network classification and learning cellular automata, from the location of... 

In Mobile Ad hoc Networks (MANETs), nodes depend on each other for routing and forwarding their packets. However, to save power and other resources, nodes belonging to independent authorities may behave selfishly, and not cooperate in network activities. Such selfish behaviour poses a real threat to the proper functioning of MANETs. To cope with this situation, a motivation stimulation mechanism is required to provide sufficient incentives for nodes to forward other nodes’ packets. One Appropriate approach is to have network nodes paid in order to motivate them to cooperate with protocol. To achieve truthfulness, the payment based on the cost of transmission of packets. Since the mentioned... 

Mobile Ad-Hoc Networks (MANETs) have been studied as one of the most important technologies in the mid to late 1990s. There are several research works on types of network traffic modeling and prediction. Therefore, a very important issue is to make prediction on traffic-flows that each node handles. Because of this, prediction permits us to improve and increase the performance of the network. This project is a contributing effort to improve the traffic packets prediction by Neural Networks in MANET. The main goal of this thesis is about the recovery of data after crisis in phenomenal roads and highways. Our goal is recognizing phenomenal crisis-points in roads. In this thesis packets are...