Defining good abstractions is a central issue when one wants to understand the deep structure and basic principles that underlie computing mechanisms. This paper introduces a basic and particularly simple distributed ...
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ISBN:
(纸本)0769524923
Defining good abstractions is a central issue when one wants to understand the deep structure and basic principles that underlie computing mechanisms. This paper introduces a basic and particularly simple distributed computing abstraction suited to asynchronous distributed agreement problems. This abstraction, called Intersecting Sets, requires each process to deposit a value and allows each non-faulty process to obtain a subset of these values such that any two such sets have a non-empty intersection. This simple abstraction captures an essential part of distributed agreement problems. After having introduced and motivated this abstraction, the paper investigates its properties, its power and its benefit when solving distributed agreement problems.
Multi-Path routing splits a service flow into multiple flow members and each now member is routed in the network independently. This paper addresses the reliability issues in networks with multi-path routing capabilit...
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ISBN:
(纸本)0780394399
Multi-Path routing splits a service flow into multiple flow members and each now member is routed in the network independently. This paper addresses the reliability issues in networks with multi-path routing capability. We provide a novel distributed restoration solution, including the optimal number of service paths and the optimal restoration path based on the total bandwidth requirement. The proposed solution is efficient, scalable, and easy to be implemented in real networks. To assess the quality of the proposed solution, the total bandwidth requirement is first compared between single path routing and multi-path routing. Then the total restoration bandwidth requirement for multi-path routing is compared between disjoint shortest restoration path selection algorithm and the proposed restoration path selection algorithm. Simulation results show that multi-path routing is able to reduce total bandwidth requirement more than 12% than single path routing and the proposed restoration path selection algorithm can further reduce the total restoration bandwidth about 20% on multi-path routing.
We propose a novel approach for sparse topology generation in wireless ad hoc networks based on a graph structure known as beta-skeletons. Two efficient algorithms are presented in this paper for creating a connected ...
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ISBN:
(纸本)0780389913
We propose a novel approach for sparse topology generation in wireless ad hoc networks based on a graph structure known as beta-skeletons. Two efficient algorithms are presented in this paper for creating a connected topology from an underlying beta-skeleton. One algorithm is a localized algorithm that uses two-hop neighborhood information to generate a connected topology, with a running time of O(n). The other is a distributed algorithm that runs on each component of the beta-skeleton creating a connected structure from the disconnected beta-skeleton graph, the running time is O(nlogn). Simulations show consistent decrease in node degree in the resulting topology. The observed decrease is greater than 33% in comparison to the Relative Neighborhod Graph (RNG) and greater than 50% in comparison to other topology structures such as, the Gabriel Graph (GG) and the Yao construction on GG.
Bluetooth is a promising wireless technology that enables devices to form short-range multihop wireless ad-hoe networks, or personal area networks. However, the Bluetooth scatternet formation is one of the challenges ...
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ISBN:
(纸本)081945804X
Bluetooth is a promising wireless technology that enables devices to form short-range multihop wireless ad-hoe networks, or personal area networks. However, the Bluetooth scatternet formation is one of the challenges that need to be resolved since the performance of a Bluetooth network depends largely on the scatternet topology used. We first present a height-balanced binary tree, termed ACB-tree for almost-complete-binary tree, that allows two such trees to be combined to create a larger ACB-tree retaining the height-balance requirements. And, then propose a distributed scatternet formation algorithm to create ACB-trees: the generated scatternet is shown to minimize the number of piconets and provide a logarithmic-diameter in the multihop interconnection network. We also present simulations, conducted using Blueware simulator, to provide experimental results to study and compare the performance of the resulting scatternets.
Sensor networks require scalable solutions to tackle huge number of sensor nodes. The scalable solutions have to be energy efficient and robust in order that reliability and network lifetime is increased. Hierarchical...
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ISBN:
(纸本)078039206X
Sensor networks require scalable solutions to tackle huge number of sensor nodes. The scalable solutions have to be energy efficient and robust in order that reliability and network lifetime is increased. Hierarchical (cluster based) models are known to be promising solutions to the problem of scalability. In this paper we propose a distributed clustering strategy which restricts the number of nodes in each cluster, S and also limits the number of next hop neighbours of a node in a cluster, D (admissible degree). The clustering algorithm is simulated and compared with two other clustering algorithms, HEED and LEACH. Simulation results depict that the energy drain in our algorithm is much lesser than the other two algorithms, thereby providing a longer lifetime v.,hen compared to the other algorithms. The proposed algorithm provides for almost 5 times increase in the lifetime of the network, when compared to the other two algorithms.
The static frequency assignment problem on cellular networks can be abstracted as a multicoloring problem on a weighted graph, where each vertex of the graph is a base station in the network, and the weight associated...
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ISBN:
(纸本)3540259201
The static frequency assignment problem on cellular networks can be abstracted as a multicoloring problem on a weighted graph, where each vertex of the graph is a base station in the network, and the weight associated with each vertex represents the number of calls to be served at the vertex. The edges of the graph model interference constraints for frequencies assigned to neighboring stations. In this paper, we first propose an algorithm to multicolor any weighted planar graph with at most W-11/6 colors, where W denotes the weighted clique number. Next, we present a polynomial time approximation algorithm which garantees at most 2W colors for multicoloring a power square mesh. Further, we prove that the power triangular mesh is a subgraph of the power square mesh. This means that it is possible to multicolor the power triangular mesh with at most 2W colors, improving on the known upper bound of 4W. Finally, we show that any power toroidal mesh can be multicolored with strictly less than 4W colors using a distributed algorithm.
Failure detectors of the class denoted P-t eventually suspect all crashed processes in a permanent way (completeness) and ensure that, at any time, no more than n - t - 1 alive processes are falsely suspected (accurac...
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ISBN:
(纸本)3540257233
Failure detectors of the class denoted P-t eventually suspect all crashed processes in a permanent way (completeness) and ensure that, at any time, no more than n - t - 1 alive processes are falsely suspected (accuracy), n being the total number of processes. This paper rst shows that a simple combination of such a failure detector with a two-step communication pattern can provide the processes with an interesting intersection property on sets of values. As an example illustrating the bene t and the property that such a combination can provide when designing protocols, a leader-based consensus protocol whose design relies on its systematic use is presented. Then the paper presents a P-t-based protocol that builds quorums in systems where up to t processes can crash with t < n.
This paper considers an Internet agent system in which a tremendous number of agents operate, frequently appearing and disappearing, and discusses the fault-tolerant algorithm. Application of the snapshot algorithm to...
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This paper considers an Internet agent system in which a tremendous number of agents operate, frequently appearing and disappearing, and discusses the fault-tolerant algorithm. Application of the snapshot algorithm to the agent system is considered. The snapshot algorithm is used to view the whole Situation (snapshot) of the distributed system. The snapshot algorithm of Chandy and Lamport [2] is considered as a representative snapshot algorithm, in terms of the high efficiency and the simplicity of the procedure. It is not practical, however, to apply their snapshot algorithm to the distributed agent system in which a tremendous number of agents operate. From Such a viewpoint, this paper extends the idea of Chandy and Lamport's algorithm and proposes a subsnapshot algorithm, in which the snapshot is taken among the agents who are in the causal relation, through message exchange and agent creation. Then, an efficient rollback algorithm is proposed, which is based oil the snapshots taken by the subsnapshot algorithm. In the general rollback algorithm utilizing the snapshot, all agents must roll back. In contrast, in the rollback algorithm proposed in this paper, it suffices that only some agents should roll back. (C) 2005 Wiley Periodicals, Inc.
This paper analyzes the Parallel Packet Switch(PPS) architecture and studies how to guarantee its performance. Firstly a model of Stable PPS (SPPS) is proposed. The constraints of traffic scheduling algorithms, the nu...
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This paper analyzes the Parallel Packet Switch(PPS) architecture and studies how to guarantee its performance. Firstly a model of Stable PPS (SPPS) is proposed. The constraints of traffic scheduling algorithms, the number of switching layers and internal speedup, for both bufferless and buffered SPPS architecture, are theoretically analyzed. Based on these results, an example of designing a scalable SPPS with 1.28T capacity is presented, and practical considerations on implementing the scheduling algorithm are discussed. Simulations are carried out to investigate the validity and delay performance of the SPPS architecture.
This paper presents a consensus protocol for asynchronous distributed systems made up of n processes, where up to f<n/4 processes can behave arbitrarily (Byzantine processes). The protocol assumes that the underlyi...
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This paper presents a consensus protocol for asynchronous distributed systems made up of n processes, where up to f
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