In [5], we have given a straightforward distributed implementation of the Kanellakis-Smolka 'naive' algorithm for reducing labeled transition systems modulo strong bisimulation. The algorithm proceeds by parti...
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In [5], we have given a straightforward distributed implementation of the Kanellakis-Smolka 'naive' algorithm for reducing labeled transition systems modulo strong bisimulation. The algorithm proceeds by partition refinement, that is by computing increasingly fine-grained partitions of the set of states. In this paper we present an optimized distributed implementation, in which the refinements are no longer entirely recomputed in every iteration, but they are computed incrementally. A second significant improvement is the overlap between communication and computation, that results in a better use of both memory and processing power. We discuss these optimizations and show experimental results.
An approach is proposed for constructing a dependable server cluster composed only of server nodes with all nodes running the same algorithm. The cluster propagates an IP multicast address as the server address, and c...
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An approach is proposed for constructing a dependable server cluster composed only of server nodes with all nodes running the same algorithm. The cluster propagates an IP multicast address as the server address, and clients multicast requests to the cluster. A local proxy running on each client machine enables conventional client software designed for unicasting to communicate with the cluster without having to be modified. Evaluation of a prototype system providing domain name service showed that a cluster using this technique has high dependability with acceptable performance degradation.
In this paper we propose a delay-constrained distributed multicast routing algorithm based on token passing. This algorithm is fully distributed and generates a multicast routing tree, which not only meets the real-ti...
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ISBN:
(纸本)0769515797
In this paper we propose a delay-constrained distributed multicast routing algorithm based on token passing. This algorithm is fully distributed and generates a multicast routing tree, which not only meets the real-time requirement, but also has a sub-optimal network cost. Simulations have been done and the results have shown that the multicast routing tree generated by our algorithm has better performance than previously known results.
In this paper we study tire problem of assigning paths to packets oil N x N tori in an on-line and distributed fashion. By on-line we mean that the routing decisions must be made without any knowledge of future reques...
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In this paper we study tire problem of assigning paths to packets oil N x N tori in an on-line and distributed fashion. By on-line we mean that the routing decisions must be made without any knowledge of future requests. Being distributed is an equally important feature of our design. for Such algorithms need knot know the global configuration of the network in the process of routing packets. We use the technique of competitive analysis to measure the performance of our design, In addition to showing an Omega(log N) lower bound on the competitive ratio, we present both deterministic and randomized algorithms which are O(log N) competitive with respect to the maximum load (i.e., congestion) on communication links.
Sensor networks consist of autonomous wireless sensor nodes that are networked together in an ad hoc fashion. The tiny nodes are equipped with substantial processing capabilities, enabling them to combine and compress...
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Sensor networks consist of autonomous wireless sensor nodes that are networked together in an ad hoc fashion. The tiny nodes are equipped with substantial processing capabilities, enabling them to combine and compress their sensor data. The aim is to limit the amount of network traffic, and as such conserve the nodes' limited battery energy. However, due to the small packet payload, the MAC header is a significant, and energy-costly, overhead. To remedy this, we propose a novel scheme for a MAC address assignment. The two key features which make our approach unique are the exploitation of spatial address reuse and an encoded representation of the addresses in data packets. To assign the addresses, we develop a purely distributed algorithm that relies solely on local messsage exchanges. Other salient features of our approach are the ability to handle unidirectional links and the excellent scalability of both the assignment algorithm and address representation. In typical scenarios, the MAC overhead is reduced by a factor of three compared to existing approaches.
We study the quality of service (QoS) of failure detectors. By QoS, we mean a specification that quantifies 1) how fast the failure detector detects actual failures and 2) how well it avoids false detections. We first...
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We study the quality of service (QoS) of failure detectors. By QoS, we mean a specification that quantifies 1) how fast the failure detector detects actual failures and 2) how well it avoids false detections. We first propose a set of QoS metrics to specify failure detectors for systems with probabilistic behaviors, i.e., for systems where message delays and message losses follow some probability distributions. We then give a new failure detector algorithm and analyze its QoS in terms of the proposed metrics. We show that, among a large class of failure detectors, the new algorithm is optimal with respect to some of these QoS metrics. Given a set of failure detector QoS requirements, we show how to compute the parameters of our algorithm so that it satisfies these requirements and we show how this can be done even if the probabilistic behavior of the system is not known. We then present some simulation results that show that the new failure detector algorithm provides a better QoS than an algorithm that is commonly used in practice. Finally, we suggest some ways to make our failure detector adaptive to changes in the probabilistic behavior of the network.
The mobile computing system is a set of functions on a distributed environment organized to support mobile hosts, In this environment. mobile hosts should be able to move without any constraints and should remain conn...
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The mobile computing system is a set of functions on a distributed environment organized to support mobile hosts, In this environment. mobile hosts should be able to move without any constraints and should remain connected to the network even while moving. Also, they should be able to get necessary information regardless of their current location and time. distributed mutual exclusion methods for supporting distributed algorithms have hitherto been designed for networks only with static hosts. However, with the emergence of mobile computing environments, a new distributed mutual exclusion method needs to be developed for integrating mobile hosts with underlying distributed systems. In the sense, many issues that should be considered stern from three essential properties of mobile computing system such as wireless communication, portability, and mobility. Thus far, distributed mutual exclusion methods for mobile computing environments were designed based on a token ring structure, which has the drawback of requiring high costs in order to locate. mobile. hosts. In this paper, we propose not only a distributed mutual exclusion method that can reduce such costs by structuring the entire. system as a tree-based logical structure but also recovery schemes that can be applied when a node failure occurs. Finally, we evaluate the operation costs for the mutual exclusion scheme and the, recovery scheme.
Recent advances in mobile computing and distributed multimedia systems allow mobile hosts (clients) to access wireless multimedia systems anywhere and at anytime, but not without creating a new set of issues and trade...
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Recent advances in mobile computing and distributed multimedia systems allow mobile hosts (clients) to access wireless multimedia systems anywhere and at anytime, but not without creating a new set of issues and trade-offs. To the best of our knowledge, there has been very little research dealing with the synchronization problem in wireless and mobile multimedia systems. In this paper, we propose an efficient distributed synchronization algorithm using Quasi-sink for wireless and mobile multimedia systems to ensure and facilitate mobile client access to multimedia objects. We discuss the algorithm and provide its proof of correctness. We also present a set of simulation experiments to evaluate the performance of our scheme using message complexity and buffer usage at each frame arrival time. Our results indicate that our scheme exhibits a significant low message complexity and no underflow and overflow within the bounded delivery time.
A basic problem in the design of mobile telephone networks is to assign sets of radio frequency bands (colours) to transmitters (vertices) to avoid interference. Often the transmitters are laid out like vertices of a ...
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A basic problem in the design of mobile telephone networks is to assign sets of radio frequency bands (colours) to transmitters (vertices) to avoid interference. Often the transmitters are laid out like vertices of a triangular lattice in the plane. We investigate the corresponding colouring problem of assigning sets of colours of size p(v) to each vertex of the triangular lattice so that the sets of colours assigned to adjacent vertices are disjoint. A n-[p]colouring of a graph G is a mapping c from V(G) into the set of the subsets of {1,2,...,n} such that \c(v)\=p(v) and for any adjacent vertices u and v, c(u)boolean ANDc(v)=empty set. We give here an alternative proof of the fact that every triangular-free induced subgraph of the triangular lattice is 5-[2]colourable. This proof yields a constant time distributed algorithm that finds a 5-[2]colouring of such a graph. We then give a distributed algorithm that finds a [p]colouring of a triangle-free induced subgraph of the triangular lattice with at most 5omega(p)(G)/4 + 3 colours. (C) 2002 Elsevier Science B.V. All rights reserved.
Ad-hoc networks are a new wireless networking paradigm for mobile hosts. Unlike conventional wireless networks, ad-hoc networks have no fixed network infrastructure or administrative support. The topology of the netwo...
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ISBN:
(纸本)0780375335
Ad-hoc networks are a new wireless networking paradigm for mobile hosts. Unlike conventional wireless networks, ad-hoc networks have no fixed network infrastructure or administrative support. The topology of the network changes dynamically as mobile nodes join or depart the network or radio links between nodes become unusable. In this paper we propose some efficient multi-path approaches that provide more secure routing schemes for ad-hoc network than previous ones. Within these approaches, more than one routing paths are selected. With the underlying coding technique, it can guarantee security against some malicious parties(it depends on how robust system is.) Moreover, we apply these schemes into existing ad-hoc network routing protocols, table-driven and on-demand routing algorithms. Finally, we derive the relation between some probabilities on our algorithms.
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