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## Performance evaluation of routing protocols for MANETs with known connectivity patterns using evolving graphs

FERREIRA, Afonso; GOLDMAN, Alfredo; MONTEIRO, Julian
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.46%
The assessment of routing protocols for mobile wireless networks is a difficult task, because of the networks` dynamic behavior and the absence of benchmarks. However, some of these networks, such as intermittent wireless sensors networks, periodic or cyclic networks, and some delay tolerant networks (DTNs), have more predictable dynamics, as the temporal variations in the network topology can be considered as deterministic, which may make them easier to study. Recently, a graph theoretic model-the evolving graphs-was proposed to help capture the dynamic behavior of such networks, in view of the construction of least cost routing and other algorithms. The algorithms and insights obtained through this model are theoretically very efficient and intriguing. However, there is no study about the use of such theoretical results into practical situations. Therefore, the objective of our work is to analyze the applicability of the evolving graph theory in the construction of efficient routing protocols in realistic scenarios. In this paper, we use the NS2 network simulator to first implement an evolving graph based routing protocol, and then to use it as a benchmark when comparing the four major ad hoc routing protocols (AODV, DSR, OLSR and DSDV). Interestingly...

## Uso de grafos evolutivos no roteamento em redes dinâmicas: algoritmos, fluxos e limites; Using evolving graphs in routing of dynamic networks: algorithms, flows and bounds

Monteiro, Julian Geraldes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
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O comportamento dinâmico das redes sem fio as torna muito peculiares e de difícil análise. No entanto, algumas destas redes, como as de sensores com funcionamento intermitente, redes periódicas ou cíclicas e as do sistema de satélites de órbita baixa têm um comportamento dinâmico relativamente previsível, pois as variações da topologia da rede no tempo são quase que determinísticas. Recentemente, um modelo teórico -- grafos evolutivos -- foi proposto com o intuito de capturar o comportamento dinâmico destas redes e formalizar algoritmos de roteamento de custo mínimo, além de outros. Os algoritmos e idéias obtidos com este modelo são teoricamente muito eficientes, mas, no entanto, antes deste trabalho não existiam estudos do uso destes modelos em situações práticas. Assim, o objetivo deste trabalho é analisar a aplicabilidade da teoria de grafos evolutivos na construção de protocolos de roteamento eficientes em cenários realistas. Foram implementados dois protocolos de roteamento para redes móveis ad hoc baseados nos algoritmos de grafos evolutivos, são eles: Jornada que Chega Mais Cedo e Jornada Mais Curta. Extensivas simulações foram realizadas utilizando o simulador de redes NS2 e os resultados foram comparados com outros quatro protocolos clássicos para este tipo de rede: AODV...

## Using Reputation Systems and Non-Deterministic Routing to Secure Wireless Sensor Networks

Moya, José M.; Vallejo, Juan Carlos; Fraga, David; Araujo, Álvaro; Villanueva, Daniel; de Goyeneche, Juan-Mariano
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.37%
Security in wireless sensor networks is difficult to achieve because of the resource limitations of the sensor nodes. We propose a trust-based decision framework for wireless sensor networks coupled with a non-deterministic routing protocol. Both provide a mechanism to effectively detect and confine common attacks, and, unlike previous approaches, allow bad reputation feedback to the network. This approach has been extensively simulated, obtaining good results, even for unrealistically complex attack scenarios.

## Relaxing Routing Table to Alleviate Dynamism in P2P Systems

Fang, Hui; Hsu, Wen Jing; Rudolph, Larry
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Artigo de Revista Científica Formato: 85408 bytes; application/pdf
Português
Relevância na Pesquisa
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In dynamic P2P networks, nodes join and depart from the system frequently, which partially damages the predefined P2P structure, and impairs the system performance such as basic lookup functionality. Therefore stabilization process has to be done to restore the logical topology. This paper presents an approach to relax the requirement on routing tables to provide provably better stability than fixed structured P2P systems. We propose a relaxed Chord that keeps the O(logN) number of hops for greedy lookup, but it requires less stabilization overhead. It allows a tradeoff between lookup efficiency and structure flexibility without adding any overhead to the system. In the relaxed routing structure, each routing entry ("finger") of the node is allowed to vary within a set of values. Each node only needs to keep a certain number of fingers that point to nodes in its anchor set. This relaxation reduces the burden of state management of the node. The relaxed routing scheme provides an alternative structure other than randomized P2P and deterministic P2P, by relaxing on finger selection. It provides good flexibility and therefore extends the system functioning time.; Singapore-MIT Alliance (SMA)

## Selection, Sorting, and Routing on Mesh-Connected Processor Arrays

Narayanan, Lata ; Krizanc, Danny
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Technical Report; Thesis
Português
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Thesis (Ph. D.)--University of Rochester. Dept. of Computer Science, 1992. Simultaneously published in the Technical Report series.; The mesh-connected processor array has been the object of a great deal of attention in recent years, and several parallel computers have configurations based on the mesh topology. This thesis addresses the fundamental problems of selection, sorting, and routing on mesh-like networks. Sorting and selection are prototype problems, due both to their practical applications and to their role in inter-processor communication. The routing problem isolates the issue of communication between processors in an interconnection network. We show efficient randomized algorithms for selection on mesh-like networks. In particular, we show that there is a 1.22n step randomized algorithm that selects the element of rank k at the middle processor of the nxn mesh, and uses constant size queues, with high probability. In the deterministic setting, we devise a 1.44n step algorithm for selection at the middle processor. For the case when there are N elements distributed at the nodes of an nxn mesh (N > n^2), we show a deterministic algorithm that works in O(min{n^2 log (N/n^2), max{N/n^{4/3}, n}}) steps. We show optimal algorithms for selection in a variety of restricted settings: at specific locations in the mesh; when the inputs are chosen from a small domain; and for elements with specific ranks. We are able to show that adding the toroidal and/or diagonal connections to the mesh yields better algorithms for selection. We exhibit improved randomized and deterministic algorithms for selection in higher-dimensional meshes. The bounds for sorting and selection on the mesh seem to be very model-dependent. We define a general model of computation that has the queue size and the ability to replicate packets as parameters. We prove lower bounds for sorting and selection in some incarnations of this model. The architectures we consider are meshes and tori...

## Control strategies for the vehicle routing problem applied to medical emergencies

CHINI, GIORGIA
Português
Relevância na Pesquisa
36.3%
This thesis deals with dynamic Multi-Vehicle Routing Problem (MVRP) in both deterministic and stochastic scenarios. The objective of the MVRP is to find the best paths for a fleet of vehicles, with the aim of visiting a set of targets. Based on the Cooperative Receding Horizon (CRH) approach proposed by Cassandras et al.(CRH) for the Euclidean case, this thesis: i) presents another algorithm that is more efficient with clustered targets (tCRH); ii) illustrates an algorithm that exploits CRH and tCRH strengths (aCRH); iii) extends CRH, tCRH and aCRH to realistic urban map case.

## Real-Time QoS Routing Protocols in Wireless Multimedia Sensor Networks: Study and Analysis

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Many routing protocols have been proposed for wireless sensor networks. These routing protocols are almost always based on energy efficiency. However, recent advances in complementary metal-oxide semiconductor (CMOS) cameras and small microphones have led to the development of Wireless Multimedia Sensor Networks (WMSN) as a class of wireless sensor networks which pose additional challenges. The transmission of imaging and video data needs routing protocols with both energy efficiency and Quality of Service (QoS) characteristics in order to guarantee the efficient use of the sensor nodes and effective access to the collected data. Also, with integration of real time applications in Wireless Senor Networks (WSNs), the use of QoS routing protocols is not only becoming a significant topic, but is also gaining the attention of researchers. In designing an efficient QoS routing protocol, the reliability and guarantee of end-to-end delay are critical events while conserving energy. Thus, considerable research has been focused on designing energy efficient and robust QoS routing protocols. In this paper, we present a state of the art research work based on real-time QoS routing protocols for WMSNs that have already been proposed. This paper categorizes the real-time QoS routing protocols into probabilistic and deterministic protocols. In addition...

## Online Permutation Routing in Partitioned Optical Passive Star Networks

Mei, Alessandro; Rizzi, Romeo
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.51%
This paper establishes the state of the art in both deterministic and randomized online permutation routing in the POPS network. Indeed, we show that any permutation can be routed online on a POPS network either with $O(\frac{d}{g}\log g)$ deterministic slots, or, with high probability, with $5c\lceil d/g\rceil+o(d/g)+O(\log\log g)$ randomized slots, where constant $c=\exp (1+e^{-1})\approx 3.927$. When $d=\Theta(g)$, that we claim to be the "interesting" case, the randomized algorithm is exponentially faster than any other algorithm in the literature, both deterministic and randomized ones. This is true in practice as well. Indeed, experiments show that it outperforms its rivals even starting from as small a network as a POPS(2,2), and the gap grows exponentially with the size of the network. We can also show that, under proper hypothesis, no deterministic algorithm can asymptotically match its performance.

## RTXP : A Localized Real-Time Mac-Routing Protocol for Wireless Sensor Networks

Mouradian, Alexandre; Augé-Blum, Isabelle; Valois, Fabrice
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.56%
Protocols developed during the last years for Wireless Sensor Networks (WSNs) are mainly focused on energy efficiency and autonomous mechanisms (e.g. self-organization, self-configuration, etc). Nevertheless, with new WSN applications, appear new QoS requirements such as time constraints. Real-time applications require the packets to be delivered before a known time bound which depends on the application requirements. We particularly focus on applications which consist in alarms sent to the sink node. We propose Real-Time X-layer Protocol (RTXP), a real-time communication protocol. To the best of our knowledge, RTXP is the first MAC and routing real-time communication protocol that is not centralized, but instead relies only on local information. The solution is cross-layer (X-layer) because it allows to control the delays due to MAC and Routing layers interactions. RTXP uses a suited hop-count-based Virtual Coordinate System which allows deterministic medium access and forwarder selection. In this paper we describe the protocol mechanisms. We give theoretical bound on the end-to-end delay and the capacity of the protocol. Intensive simulation results confirm the theoretical predictions and allow to compare with a real-time centralized solution. RTXP is also simulated under harsh radio channel...

## An Energy-Based Comparison of Long-Hop and Short-Hop Routing in MIMO Networks

Lo, Caleb K.; Vishwanath, Sriram; Heath Jr, Robert W.
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.49%
This paper considers the problem of selecting either routes that consist of long hops or routes that consist of short hops in a network of multiple-antenna nodes, where each transmitting node employs spatial multiplexing. This distance-dependent route selection problem is approached from the viewpoint of energy efficiency, where a route is selected with the objective of minimizing the transmission energy consumed while satisfying a target outage criterion at the final destination. Deterministic line networks and two-dimensional random networks are considered. It is shown that when 1) the number of hops traversed between the source and destination grows large or 2) when the target success probability approaches one or 3) when the number of transmit and/or receive antennas grows large, short-hop routing requires less energy than long-hop routing. It is also shown that if both routing strategies are subject to the same delay constraint, long-hop routing requires less energy than short-hop routing as the target success probability approaches one. In addition, numerical analysis indicates that given loose outage constraints, only a small number of transmit antennas are needed for short-hop routing to have its maximum advantage over long-hop routing...

## Upper and Lower Bounds for Competitive Online Routing on Delaunay Triangulations

Bonichon, Nicolas; Bose, Prosenjit; De Carufel, Jean-Lou; Perković, Ljubomir; Van Renssen, André
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.71%
Consider a weighted graph G where vertices are points in the plane and edges are line segments. The weight of each edge is the Euclidean distance between its two endpoints. A routing algorithm on G has a competitive ratio of c if the length of the path produced by the algorithm from any vertex s to any vertex t is at most c times the length of the shortest path from s to t in G. If the length of the path is at most c times the Euclidean distance from s to t, we say that the routing algorithm on G has a routing ratio of c.We present an online routing algorithm on the Delaunay triangulation with competitive and routing ratios of 5.90. This improves upon the best known algorithm that has competitive and routing ratio 15.48. The algorithm is a generalization of the deterministic 1-local routing algorithm by Chew on the L1-Delaunay triangulation. When a message follows the routing path produced by our algorithm, its header need only contain the coordinates of s and t. This is an improvement over the currently known competitive routing algorithms on the Delaunay triangulation, for which the header of a message must additionally contain partial sums of distances along the routing path.We also show that the routing ratio of any deterministic k-local algorithm is at least 1.70 for the Delaunay triangulation and 2.70 for the L1-Delaunay triangulation. In the case of the L1-Delaunay triangulation...

## Optimal Deterministic Routing and Sorting on the Congested Clique

Lenzen, Christoph
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.46%
Consider a clique of n nodes, where in each synchronous round each pair of nodes can exchange O(log n) bits. We provide deterministic constant-time solutions for two problems in this model. The first is a routing problem where each node is source and destination of n messages of size O(log n). The second is a sorting problem where each node i is given n keys of size O(log n) and needs to receive the ith batch of n keys according to the global order of the keys. The latter result also implies deterministic constant-round solutions for related problems such as selection or determining modes.; Comment: 16 pages, no figures; published at PODC 2013

## Exploring the Limits of Static Failover Routing

Chiesa, Marco; Gurtov, Andrei; Mądry, Aleksander; Mitrović, Slobodan; Nikolaevkiy, Ilya; Panda, Aurojit; Schapira, Michael; Shenker, Scott
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.44%
We present and study the Static-Routing-Resiliency problem, motivated by routing on the Internet: Given a graph $G$, a unique destination vertex $d$, and an integer constant $c>0$, does there exist a static and destination-based routing scheme such that the correct delivery of packets from any source $s$ to the destination $d$ is guaranteed so long as (1) no more than $c$ edges fail and (2) there exists a physical path from $s$ to $d$? We embark upon a systematic exploration of this fundamental question in a variety of models (deterministic routing, randomized routing, with packet-duplication, with packet-header-rewriting) and present both positive and negative results that relate the edge-connectivity of a graph, i.e., the minimum number of edges whose deletion partitions $G$, to its resiliency.; Comment: 28 pages

## Source Routing and Scheduling in Packet Networks

Andrews, Matthew; Fernandez, Antonio; Goel, Ashish; Zhang, Lisa
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.58%
We study {\em routing} and {\em scheduling} in packet-switched networks. We assume an adversary that controls the injection time, source, and destination for each packet injected. A set of paths for these packets is {\em admissible} if no link in the network is overloaded. We present the first on-line routing algorithm that finds a set of admissible paths whenever this is feasible. Our algorithm calculates a path for each packet as soon as it is injected at its source using a simple shortest path computation. The length of a link reflects its current congestion. We also show how our algorithm can be implemented under today's Internet routing paradigms. When the paths are known (either given by the adversary or computed as above) our goal is to schedule the packets along the given paths so that the packets experience small end-to-end delays. The best previous delay bounds for deterministic and distributed scheduling protocols were exponential in the path length. In this paper we present the first deterministic and distributed scheduling protocol that guarantees a polynomial end-to-end delay for every packet. Finally, we discuss the effects of combining routing with scheduling. We first show that some unstable scheduling protocols remain unstable no matter how the paths are chosen. However...

## A Little Prediction Goes a Long Way: Routing in Semi-Deterministic Delay Tolerant Networks

Roy, Dhrubojyoti; Sridharan, Mukundan; Deshpande, Satyajeet; Arora, Anish
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.61%
Realizing delay-capacity in intermittently connected mobile networks remains a largely open question, with state-of-the-art routing schemes typically focusing either on delay or on capacity. We show the feasibility of routing with both high goodput and desired delay constraints, with REAPER (for Reliable, Efficient, and Predictive Routing), a fully distributed convergecast routing framework that jointly optimizes both path length and path delay. A key idea for efficient instantiation of REAPER is to exploit predictability of mobility patterns, in terms of a semi-deterministic model which appropriately captures several vehicular and human inter-contact patterns. Packets are thus routed using paths that are jointly optimal at their time of arrival, in contrast to extant DTN protocols which use time-average metrics for routing. REAPER is also self-stabilizing to changes in the mobility pattern. A simulation-based evaluation confirms that, across the spectrum of ultra-light to heavy traffics, REAPER achieves up to 135% and 200% higher throughput and up to 250% and 1666% higher energy efficiency than state-of-the-art single-copy protocols MEED-DVR and PROPHET, which optimize a single metric only, specifically, expected delay and path probability respectively.; Comment: This paper has been withdrawn by the authors. Withdrawn since document intended to be anonymous

## The Routing of Complex Contagion in Kleinberg's Small-World Networks

Chen, Wei; Li, Qiang; Sun, Xiaoming; Zhang, Jialin
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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In Kleinberg's small-world network model, strong ties are modeled as deterministic edges in the underlying base grid and weak ties are modeled as random edges connecting remote nodes. The probability of connecting a node $u$ with node $v$ through a weak tie is proportional to $1/|uv|^\alpha$, where $|uv|$ is the grid distance between $u$ and $v$ and $\alpha\ge 0$ is the parameter of the model. Complex contagion refers to the propagation mechanism in a network where each node is activated only after $k \ge 2$ neighbors of the node are activated. In this paper, we propose the concept of routing of complex contagion (or complex routing), where we can activate one node at one time step with the goal of activating the targeted node in the end. We consider decentralized routing scheme where only the weak ties from the activated nodes are revealed. We study the routing time of complex contagion and compare the result with simple routing and complex diffusion (the diffusion of complex contagion, where all nodes that could be activated are activated immediately in the same step with the goal of activating all nodes in the end). We show that for decentralized complex routing, the routing time is lower bounded by a polynomial in $n$ (the number of nodes in the network) for all range of $\alpha$ both in expectation and with high probability (in particular...

## Better Online Deterministic Packet Routing on Grids

Even, Guy; Medina, Moti; Patt-Shamir, Boaz
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.56%
We consider the following fundamental routing problem. An adversary inputs packets arbitrarily at sources, each packet with an arbitrary destination. Traffic is constrained by link capacities and buffer sizes, and packets may be dropped at any time. The goal of the routing algorithm is to maximize throughput, i.e., route as many packets as possible to their destination. Our main result is an $O\left(\log n\right)$-competitive deterministic algorithm for an $n$-node line network (i.e., $1$-dimensional grid), requiring only that buffers can store at least $5$ packets, and that links can deliver at least $5$ packets per step. We note that $O(\log n)$ is the best ratio known, even for randomized algorithms, even when allowed large buffers and wide links. The best previous deterministic algorithm for this problem with constant-size buffers and constant-capacity links was $O(\log^5 n)$-competitive. Our algorithm works like admission-control algorithms in the sense that if a packet is not dropped immediately upon arrival, then it is "accepted" and guaranteed to be delivered. We also show how to extend our algorithm to a polylog-competitive algorithm for any constant-dimension grid.

## A Framework for Adaptive Routing in Multicomputer Networks

Ngai, John Y.
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/postscript; other
Relevância na Pesquisa
26.51%
Message-passing concurrent computers, also known as multicomputers, such as the Caltech Cosmic Cube [47] and its commercial descendents, consist of many computing nodes that interact with each other by sending and receiving messages over communication channels between the nodes. The communication networks of the second-generation machines, such as the Symult Series 2010 and the Intel iPSC2 [2], employ an oblivious wormhole-routing technique that guarantees deadlock freedom. The network performance of this highly evolved oblivious technique has reached a limit of being capable of delivering, under random traffic, a stable maximum sustained throughput of ~~45 to 50% of the limit set by the network bisection bandwidth, while maintaining acceptable network latency. This thesis examines the possibility of performing adaptive routing as an approach to further improving upon the performance and reliability of these networks. In an adaptive multipath routing scheme, message trajectories are no longer deterministic, but are continuously perturbed by local message loading. Message packets will tend to follow their shortest-distance routes to destinations in normal traffic loading, but can be detoured to longer but less-loaded routes as local congestion occurs. A simple adaptive cut-through packet-switching framework is described...

## Development of deterministic collision-avoidance algorithms for routing automated guided vehicles

Pai, Arun S.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Português
Relevância na Pesquisa
46.46%
A manufacturing job spends a small portion of its total flow time being processed on machines, and during the remaining time, either it is in a queue or being transported from one work center to another. In a fully automated material-handling environment, automated guided vehicles (AGV) perform the function of transporting the jobs between workstations, and high operational costs are involved in these material-handling activities. Consequently, the AGV route schedule dictates subsequent work-center scheduling. For an AGV job transportation schedule to be effective, the issue of collisions amongst AGV during travel needs to be addressed. Such collisions cause stalemate situations that potentially disrupt the flow of materials in the job shop, adding to the non-value time of job processing, and thus, increase the material handling and inventory holding costs. The current research goal was to develop a methodology that could effectively and efficiently derive optimal AGV routes for a given set of transportation requests, considering the issue of collisions amongst AGV during travel. As part of the solution approach in the proposed work, an integer linear program was formulated in Phase I with the capability of optimally predicting the AGV routes for a deterministic set of transportation requests. Collision avoidance constraints were developed in this model. The model was programmed using OPL / Visual Basic...

## A Kind of New Multicast Routing Algorithm for Application of Internet of Things

Li,G.; Zhang,D. G.; Zheng,K.; Ming,X. C.; Pan,Z. H.; Jiang,K. W.
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html