Wireless and mobile communications has experienced an unprecedented rapid growth during the last decade. Vehicular Ad Hoc Networks (VANETs) are a completely wirelessly connected through the nodes, which usually has dynamic topologies. VANETs can be employed in many applications such as traffic control, safety related message dissemination, and entertainment infotainment. Broadcast storm problem is one of the hot issues in VANETs as it lacks of central management. Many methods are proposed to solve this problem, such as p-persistence based, 1-persistance based, and counter based schemes. However, all of the related works have weaknesses that cannot be ignored either associated with intersection problem or limited environment. In this paper, a novel clustering algorithm is proposed that guarantees efficient clustering. Thereafter, an efficient cluster maintenance mechanism is proposed. Then we show how the emergency messages are transmitted in proposed cluster structure. Finally, the simulation study confirms the availability and efficiency of the proposed clustering algorithm.
Wireless sensor networks WSNs can be used in many applications. Object tracking is one of the most important applications. There are many researches about tracking individual object but few researches on tracking continuous object. Continuous object affects a large number of nodes so needs more communication and cooperation to track it comparing with individual object. In this paper we propose an energy-efficiency continuous object tracking (ECOT) protocol. In ECOT, a sensor node identify itself whether a boundary node or not via automatically adjusting its sensing range instead of communicating with neighboring nodes since radio communication which consumes much more energy than adjusting sensing range. Furthermore just a subset of boundary nodes will send data back to sink node with a small-size message by a representative node selection mechanism. Finally the sink node can estimate the object's position and shape by locating object mechanism. The analysis and simulation results demonstrate that ECOT outperform than previous work and achieves high fidelity and significantly reduces the amount of communication messages.
Mobile ad hoc networks are vulnerable to a large group of attacks, e.g., wormhole attacks. In this paper, we propose a countermeasure to prevent wormhole attacks. We utilize analytical hierarchy process to elect some special nodes, named the local most trustable nodes, for the source and the destination node, respectively. The elected nodes are then required to implement our proposed scheme to prevent wormhole attacks. The proposed scheme cannot only detect wormhole attacks, but also locate wormhole nodes, i.e., identify the malicious nodes that behave wormhole attacks. To solve the colluding wormhole attack, we present a countermeasure named bi-directional wormhole location mechanism.
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