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ABSTRACT: Multi-path routing can provide higher bandwidth and better packet delivery ratio for multimedia applications than traditional shortest path routing protocols. Multi-path routing protocols try to use multiple simultaneous paths to transfer data messages. While it might increase the bandwidth and the delivery ratio, it also distributes the traffic load more evenly over the network. This load balance can be used to increase the lifetime of a MANET, as it will avoid using only one route for many times. This article explores the load balance technique showing that it is possible to increase the network lifetime up to 22 minutes using this technique alone. The energy consumption of a MANET unit can be split into control (59%), data (34%) and routing (7%) packets. The energy used only by the network interface card can also be separated into the energy used by sending or receiving packets, in this case approximately 89% is used to receive packets. All these values were obtained through simulations on GloMoSim, performed using real values from a Compaq WL110 network interface card connected to an HP IPAQ 3600 handheld.
Circuits and Systems for Communications, 2008. ICCSC 2008. 4th IEEE International Conference on; 06/2008
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ABSTRACT: The virtual routing protocol and the virtual distance vector are hybrid routing protocols for mobile ad hoc networks which are based on virtual structures. Virtual structures are unrelated to the physical network topology and units are responsible for keeping physical routes to their neighbors in the virtual structure. The protocols were designed to work with different virtual structures, like: rings of rings RoR, hypercube, CCC and 3D-torus. This paper compares simulation results of these four different virtual structures. It will be shown through simulation results that the protocols are, to some extent, independent of the graph implementing the virtual structure.
Wireless Pervasive Computing, 2008. ISWPC 2008. 3rd International Symposium on; 06/2008
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ABSTRACT: Due to the high percentage of mobile devices thefts and the financial loss that it causes, this paper aims to develop an inexpensive framework to identify a user to his/her mobile device. In case the user is not successfully identified the mobile devices' manager blocks the device completely, avoiding use of any service, including calls, browsing the Internet, sending SMS and accessing personal data, such as contacts, last calls made and received, among others. Experiments using PDAs are presented to demonstrate the feasibility of this project.
Consumer Communications and Networking Conference, 2008. CCNC 2008. 5th IEEE; 02/2008
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ABSTRACT: This work presents a new comparison-based diagnosis model and a new algorithm, called Hi-Dif, based on this model. The algorithm is used for checking the integrity of systems with replicated data, for instance, detecting unauthorized Web page modifications. Fault-free nodes running Hi-Dif send a task to two other nodes and the task results are compared. If the comparison produces a match, the two nodes are classified in the same set. On the other hand, if the comparison results in a mismatch, the two nodes are classified in different sets, according to their task results. One of the sets always contains all fault-free nodes. One fundamental difference of the proposed model to previously published models is that the new model allows the task outputs of two faulty nodes to be equal to each other. Considering a system of N nodes, we prove that the algorithm has latency equal to log<sub>2</sub>N testing rounds in the worst case; that the maximum number of tests required is O(N<sup>2</sup>); and, that the algorithm is (N-1)-diagnosable. Experimental results obtained by simulation and by the execution of a tool implemented applied to the Web are presented.
Parallel and Distributed Systems, 2005. Proceedings. 11th International Conference on; 08/2005
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ABSTRACT: The components of a fault-tolerant distributed system must be capable to accurately determine which components of the system are faulty and which are fault-free. In this paper, we present a new distributed algorithm for event diagnosis in fully-connected networks. An event is defined as a faulty node becoming fault-free, or vice versa. Previous hierarchical algorithms considered a static fault situation, in which an event can only occur after a previous event has been fully diagnosed. The new algorithm is capable of achieving the diagnosis of dynamic events as long as the nodes stay in a given state for a period of time long enough for all testers to detect that state. Each node running the algorithm keeps a timestamp for the state of each other node in the system. This timestamp is implemented as a counter, which is incremented every time a node changes its state. In this way, each tester may obtain information about a given node in the system from more than one tested node without causing any inconsistencies, i.e. without taking an older state for a newer one. Nodes run a hierarchical testing strategy, which is a hypercube when all nodes are fault-free. When a fault-free node is tested, the tester gets diagnostic information about N/2 nodes for a system of N nodes. In spite of the overhead of keeping and transferring timestamps, the new algorithm significantly reduces the average latency when compared to other similar approaches, presenting a new option for practical diagnosis implementation
Parallel and Distributed Systems, 2000. Proceedings. Seventh International Conference on; 02/2000
