Sharif Digital Repository

Security in mobile ad hoc networks (MANETs) is an active research topic. Bulks of prior work focused on key management and secure routing without addressing an important pre-requisite: network access control, the problem of how securely extend the network. In this paper, we present INAC, an identity-based network access control scheme for MANETs. In INAC, each node in the network must have an identity-based membership token in order to take part in network activities. Membership tokens have special formats, which not only guarantee security of non-compromised nodes, but also enable that nodes obtain identity-based membership tokens based on their trustworthiness. Through simulations we... 

In the past few years, the study of complex networks has attracted the attention of researchers. Many real networks, ranging from technological networks such as the Internet to biological networks, have been considered as special types of complex networks. Through application of the network science, important structural properties of such networks have been analyzed and the mechanisms that form such characteristics have been introduced. In this paper, we address the structural characteristics of a technological network called Vehicular Ad hoc Networks (VANETs). Recent studies reveal that the communication graph of VANETs has some interesting characteristics including: the Gaussian degree... 

During the last years, researche'rs have proposed solutions to help smartphones improve execution time and reduce energy consumption by offloading heavy tasks to remote entities. Lately, inspired by the promising results of message forwarding in opportunistic networks, many researchers have proposed strategies for task offloading towards nearby mobile devices, giving birth to the Device-to-Device offloading paradigm. None of these strategies, though, offers any mechanism that considers selfish users and, most importantly, that motivates and defrays the participating devices who spend their resources. In this paper, we address these problems and propose the design of a framework that... 

One of the intrinsic problems of mobility in wireless networks is the discovery of mobile nodes. A widely used solution for this problem is to use different variations of beacons, such as hello packets. Although a poorly designed beaconing scheme may lead to unnecessary energy usage or poor throughput, a systematic approach to analyze and select beaconing parameters is not provided in the literature. Here, we propose a model to study the beaconing efficiency using some measures such as the link lifetime, the probability of link establishment, and the delay to discover a new neighbor. The model is general and does not adhere to any particular mobility model; the only input from the mobility... 

We introduced Computed Network Process Theory to reason about protocols for mobile ad hoc networks (MANETs). Here we explore the applicability of our framework in two regards: model checking and equational reasoning. The operational semantics of our framework is based on constrained labeled transition systems (CLTSs), in which each transition label is parameterized with the set of topologies for which this transition is enabled. We illustrate how through model checking on CLTSs one can analyze mobility scenarios of MANET protocols. Furthermore, we show how by equational theory one can reason about MANETs consisting of a finite but unbounded set of nodes, in which all nodes deploy the same... 

We provide an equational theory for Restricted Broadcast Process Theory to reason about ad hoc networks. We exploit an extended algebra called Computed Network Theory to axiomatize restricted broadcast. It allows one to define the behavior of an ad hoc network with respect to the underlying topologies. We give a sound and ground-complete axiomatization for CNT terms with finite-state behavior, modulo what we call rooted branching computed network bisimilarity  

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 paper, a new framework called Mobility Analyzer has been introduced for analysis and recognition of mobility traces. At first, the Mobility Analyzer acquires some mobility traces collected by GPS or generated with mobility simulators; then it calculates some mobility metrics which represent the movement behavior of the mobile nodes; finally it attempts to classify mobility traces into particular mobility models... 

Cooperation among nodes is important in ad hoc networks since in such networks nodes depend on each other for forwarding packets. However, cooperation in such operations consumes nodes energy and recourses. Therefore, it is necessary to design incentive mechanisms to enforce nodes to forward packets when the source and destination of the packet are other nodes in the network. We study routing in ad hoc and wireless networks from a game theoretic view point. Based on this view, the network consists of selfish and greedy nodes who accept payments for forwarding data for other nodes if the payments cover their individual costs incurred by forwarding data. Also, route falsification attacks are... 

In this paper, we illustrate the design of a cross layered MAC and routing solution for supporting the fast propagation of broadcast messages at intersections in a Vehicular Ad Hoc Network (VANET). One of the fundamental services in VANET is broadcasting, that is a challenging task due to different road topologies and network conditions. One of its challenges is broadcasting at intersections, because vehicles in different roads constituting an intersections can affect on broadcast process of other roads, message may not be propagated in some directions. In this paper we propose a cross layered method that by classifying vehicles based on their location and the road they move in, solves this... 

Cooperation of nodes for routing and packet forwarding is inevitable in a mobile ad hoc network. Selfishness in such networks is a significant challenge and can cause network performance to noticeably degrade. In this paper, we propose some new selfishness models elicited from psychological behavior of human beings. We also evaluate performance of MANET in the presence of different percentages of selfish nodes that act based on our selfishness models. Results show that energy-based selfishness is a serious problem that could affect performance depends on mobility of nodes, density of network, and time of simulation. This kind of selfishness needs a comprehensive mechanism to cope with and we... 

The IEEE 802.11 provides a MAC layer protocol for controlling competition among nodes to access the channel in wireless local area network. Recent works show that this standard has not suitable performances in mobile ad-hoc networks and especially in error prone channels. Many researchers proposed many algorithms to improve this standard like HBCWC (History Based Contention Window Control) scheme has significant performances but also has fairness problem. In this paper, we present a novel contentionbased protocol to improve fairness and throughput together. We use an array to keep history of network collision and based on array information, we optimize the contention window. The main point... 

Task-based self-organizing algorithms have been proposed as a solution for the management of mobile ad-hoc networks (MANETs). Such algorithms assign tasks to nodes by sequentially selecting the best nodes as leaders. Since the correct functionality of such algorithms depends on the truthfulness of participant nodes, any misbehavior can disrupt the operation of the network due to absence of a centralized monitoring unit. In this paper, we consider the problem of malicious behavior in leader-based MANETs. Current solution analyzes the behavior of the leader by means of some checker nodes. This approach is vulnerable since a malicious checker can ruin the character of a normal behaving leader,... 

Authentication is an essential security requirement in safety-related vehicle-to-vehicle applications in VANETs. TESLA is one of the most popular broadcast source authentication protocols proposed and standardized for this purpose. Having strict time constraints and being prone to GPS synchronization errors make the analysis of this protocol challenging. In this paper, we utilize a timed model checking approach based on timed colored Petri nets to model and verify TESLA considering its time-sensitive behaviors. In this way, we show how neglecting timing aspects in protocol design and in protocol modelling can lead to successfully launched attacks and erroneous analyses respectively, and how...