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Efficient wireless network simulations with detailed propagation models

WIRELESS NETWORKS 2001年第3期7卷 297-305页

作者： Takai, M Bagrodia, R Tang, K Gerla, M Univ Calif Los Angeles Dept Comp Sci Los Angeles CA 90095 USA

Accurate simulation of wireless networks requires realistic models of the channel propagation medium. The widely used free space model is computationally efficient but ignores many attenuation components which affect wireless signal propagation. This paper describes the impact of the accuracy of the wireless channel model on the accuracy of the results and on the execution time of large-scale network models. It then introduces means to reduce the runtime execution when deploying such detailed propagation models.

关键词： discrete-event simulation wireless network modeling and design parallel and distributed simulation

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Towards large scale optimistic VLSI simulation

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simulation MODELLING PRACTICE AND THEORY 2006年第6期14卷 695-711页

作者： Xu, Qing Tropper, Carl McGill Univ Sch Comp Sci Montreal PQ H3A 2A7 Canada

In this paper, an optimistic parallel and distributed logic simulator, XTW, is proposed. In XTW, a new event scheduling mechanism, XEQ, and a new rollback procedure, rb-messages, are proposed for use in optimistic logic simulation. XTW groups LPs into clusters, and makes use of a multi-level queue, XEQ, to schedule events in the cluster. XEQ has an O(1) event scheduling time complexity. Our new rollback mechanism replaces the use of anti-messages by an rb-message, and eliminates the need for an output queue at each LP. Experimental comparisons to Clustered Time Warp reveal a superior performance on the part of XTW, while experimental results on large circuits (5-million-gate to 25-million-gate) demonstrate that XTW scales well with both the,size of a circuit and the number of processors used in the simulation. (C) 2005 Elsevier B.V. All rights reserved.

关键词： Time Warp VLSI simulation parallel and distributed simulation logic simulation event queue discrete event simulation

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The simulation model partitioning problem: An adaptive solution based on self-Clustering

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simulation MODELLING PRACTICE AND THEORY 2017年 70卷 1-20页

作者： D'Angelo, Gabriele Univ Bologna Dept Comp Sci & Engn Mura Anteo Zamboni 7 I-40127 Bologna Italy

This paper is about partitioning in parallel and distributed simulation. That means decomposing the simulation model into a number of components and to properly allocate them on the execution units. An adaptive solution based on self-clustering, that considers both communication reduction and computational load-balancing, is proposed. The implementation of the proposed mechanism is tested using a simulation model that is challenging both in terms of structure and dynamicity. Various configurations of the simulation model and the execution environment have been considered. The obtained performance results are analyzed using a reference cost model. The results demonstrate that the proposed approach is promising and that it can reduce the simulation execution time in both parallel and distributed architectures. (C) 2016 Elsevier B.V. All rights reserved.

关键词： simulation parallel and distributed simulation Load balancing Adaptive systems Middleware

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An agent-based parallel geo-simulation of urban mobility during city-scale evacuation

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simulation-TRANSACTIONS OF THE SOCIETY FOR MODELING AND simulation INTERNATIONAL 2013年第10期89卷 1184-1214页

作者： Zia, Kashif Farrahi, Katayoun Riener, Andreas Ferscha, Alois Johannes Kepler Univ Linz Pervas Comp Inst A-4040 Linz Austria

The simulation of urban mobility is a modeling challenge due to the complexity and scale. The complexity in modeling a social agent is due to three reasons: (i) the agent is behaviorally complex itself due to several interrelated/overlapping modeling aspects;(ii) the setting in which a social agent operates usually demands a multi-resolution approach;and (iii) the consideration of real spatial and population data is the underpinning that has to be realized. In this paper, we propose an agent-based parallel geo-simulation framework of urban mobility based on necessary modeling aspects. The aspect-oriented modeling paradigm relates the models vertically as well as horizontally and highlights the situations requiring multi-resolution interfacing. The framework takes into consideration the importance of technological footprints embedded with social behavior along with essential space and mobility features keeping focus on the importance of the city-scale scenario. We have used a real, high-quality raster map of a medium-sized city in central Europe converting it into a cellular automata (CA). The fine-grained CA readily supports pedestrian mobility and can easily be extended to support other mobility modes. The urban mobility simulation is performed on a real parallel and distributed hardware platform using a CA compatible software platform. Considering city-wide mobility in an emergency scenario, an analysis of the simulation efficiency and agent behavioral response is presented.

关键词： City-scale evacuation parallel and distributed simulation urban mobility large-scale agent-based modeling geo-simulation computational social science

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An intelligent scheduling algorithm for complex manufacturing system simulation with frequent synchronizations in a cloud environment

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MEMETIC COMPUTING 2019年第4期11卷 357-370页

作者： Yao, Feng Yao, Yiping Xing, Lining Chen, Huangke Lin, Zhongwei Li, Tianlin Natl Univ Def Technol Coll Syst Engn Changsha Peoples R China Shanghai Polytech Univ Coll Engn Shanghai Peoples R China Natl Univ Def Technol Coll Elect Warfare Hefei Peoples R China

For cloud-based, large-scale complex manufacturing system simulation (CMSS), allocating appropriate service instances (virtual machines or nodes) is a promising way to improve execution efficiency. However, the complex interactions among and frequent aperiodic synchronizations of the entities of a CMSS make it challenging to estimate the influence of service instances' computing power and network latency on the execution efficiency. This hinders the appropriate allocation of service instances for CMSS. To solve this problem, we construct a performance estimation model (PEM) using the executed events and synchronization algorithms to evaluate the running time of CMSS on different service instance combinations. Further, an intelligent scheduling algorithm that introduces PEM as fitness function is proposed to search for a near-optimal allocation scheme of CMSS service instances. To be specific, the PEM-based optimization algorithm (PEMOA) incorporates simulated annealing into the mutation phase of a genetic algorithm to strengthen its local searching ability. A series of experiments were performed on a computer cluster to compare the proposed PEMOA with two representative algorithms: an adapted first-come-first-service-based and the max-min-based allocation algorithms. The experimental results demonstrate that the PEMOA can reduce the running time by more than 7%. In particular, the improvement of PEMOA increases when the manufacturing system simulation is communication-intensive or spans a small number of service instance combinations.

关键词： Frequent synchronizations Intelligent manufacturing Manufacturing system Performance estimation parallel and distributed simulation Resource allocation

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Predetermined Rollbacks: An extension to Time Warp for spatially parallel agent-based simulation

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simulation MODELLING PRACTICE AND THEORY 2019年第0期95卷 60-77页

作者： Gorur, Bilge Kaan Imre, Kayhan M. Oguztuzun, Halit Yilmaz, Levent Hacettepe Univ Dept Comp Engn Ankara Turkey Middle East Tech Univ Dept Comp Engn Ankara Turkey Auburn Univ Dept Comp Sci & Software Engn Auburn AL 36849 USA

Time management is an important factor that affects the speed of parallel and distributed simulations. Conservative time management mechanisms advance simulation time after synchronization of logical processes, whereas optimistic time management mechanisms loosen synchronization among processes to speed up simulation. Because of loosened synchronization, the optimistic approaches are vulnerable to causality faults that must be addressed by logical processes during run-time. Repairing a simulation, by means of a rollback mechanism, is one of the most time-consuming processes of optimistic approaches. In this paper, we propose a method that considers precautionary measures against possible future rollbacks for Time Warp mechanism due to Jefferson. Our proposed method, named Predetermined Rollbacks, uses a modified simulation engine that can detect and avoid unnecessary rollbacks. Our experiments demonstrate that the proposed method can significantly improve the speedup of Time Warp in agent-based simulations, where agents communicate in a shared environment.

关键词： parallel and distributed simulation Optimistic time management Time warp Agent based modeling and simulation Predetermined rollbacks Spatially parallel simulation

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Performance evaluation of conservative algorithms in parallel simulation languages

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IEEE TRANSACTIONS ON parallel AND distributed SYSTEMS 2000年第4期11卷 395-411页

作者： Bagrodia, RL Takai, M Univ Calif Los Angeles Dept Comp Sci Los Angeles CA 90095 USA

parallel discrete event simulation with conservative synchronization algorithms has been used as a high performance alternative to sequential simulation. In this paper, we examine the performance of a set of parallel conservative algorithms that have been implemented in the Maisie parallel simulation language. The algorithms include the asynchronous null message algorithm, the synchronous conditional event algorithm, and a new hybrid algorithm called Accelerated Null Message that combines features from the preceding algorithms. The performance of the algorithms is compared using the Ideal simulation Protocol. This protocol provides a tight lower bound on the execution time of a simulation model on a given architecture and serves as a useful base to compare the synchronization overheads of the different algorithms. The performance of the algorithms is compared as a function of various model characteristics that include model connectivity, computation granularity, load balance, and lookahead.

关键词： discrete-event simulation parallel and distributed simulation conservative algorithms parallel simulation languages lookahead algorithmic efficiency

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An analytical model for hybrid checkpointing in Time Warp distributed simulation

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IEEE TRANSACTIONS ON parallel AND distributed SYSTEMS 1998年第10期9卷 947-951页

作者： Soliman, HM Elmaghraby, AS King Saud Univ Coll Comp & Informat Sci Riyadh 11543 Saudi Arabia Univ Louisville Speed Sci Sch Multimedia Res Lab Louisville KY 40292 USA

The Time Warp distributed simulation algorithm uses checkpointing to save process states after certain event executions for later recovery at the time of a rollback. Two main techniques have been used for checkpointing: periodic state saving and incremental state saving. The former technique introduces large overheads in reconstructing a desired state by coasting forward from an earlier checkpointed state if the computational granularity is large. The latter technique also has large overheads in applications with large rollback distances. A hybrid checkpointing technique is proposed which uses both periodic and incremental state saving simultaneously in such a way that it reduces checkpointing time overheads. A detailed analytical model is developed for the hybrid technique, and comparisons are made using similar analytical models with periodic and incremental state saving techniques. Results show that when the system parameters are chosen to represent large acid complex simulated systems, the hybrid approach has less checkpointing time overhead than the other two techniques.

关键词： Time Warp algorithm periodic checkpointing incremental state saving hybrid state saving parallel and distributed simulation

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simulation in the supply chain context: a survey

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COMPUTERS IN INDUSTRY 2004年第1期53卷 3-16页

作者： Terzi, S Cavalieri, S Politecn Milan Dept Econ Ind & Management Engn I-20133 Milan Italy Univ Bergamo Dept Ind Engn I-24044 Dalmine Italy

The increased level of competitiveness in all industrial sectors, exacerbated in the last years by the globalisation of the economies and by the sharp fall of the final demands, are pushing enterprises to strive for a further optimisation of their organisational processes, and in particular to pursue new forms of collaboration and partnership with their direct logistics counterparts. As a result, at a company level there is a progressive shift towards an external perspective with the design and implementation of new management strategies, which are generally named with the term of supply chain management (SCM). However, despite the flourish of several IT solutions in this context, there are still evident hurdles to overcome, mainly due to the major complexity of the problems to be tackled in a logistics network and to the conflicts resulting from local objectives versus network strategies. Among the techniques supporting a multi-decisional context, as a supply chain (SC) is, simulation can undoubtedly play an important role, above all for its main property to provide what-if analysis and to evaluate quantitatively benefits and issues deriving from operating in a co-operative environment rather than playing a pure transaction role with the upstream/downstream tiers. The paper provides a comprehensive review made on more than 80 articles, with the main purpose of ascertaining which general objectives simulation is generally called to solve, which paradigms and simulation tools are more suitable, and deriving useful prescriptions both for practitioners and researchers on its applicability in decision-making processes within the supply chain context. (C) 2003 Elsevier B.V. All rights reserved.

关键词： parallel and distributed simulation supply chain management high level architecture survey

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Trade-off between sequential and time warp-based parallel simulation

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IEEE TRANSACTIONS ON parallel AND distributed SYSTEMS 1999年第8期10卷 781-794页

作者： Quaglia, F Cortellessa, V Ciciani, B Univ Rome La Sapienza Dipartimento Informat & Sistemist I-00198 Rome Italy Univ Roma Tor Vergata Dipartimento Informat Sistemi & Prod I-00133 Rome Italy

Discrete event simulation is a methodology to study the behavior of complex systems. Its drawback is that, in order to get reliable results, simulations usually have to be run over a long stretch of time. This time requirement could decrease through the usage of parallel or distributed computing systems. In this paper, we analyze the Time Warp synchronization protocol for parallel discrete event simulation and present an analytical model evaluating the upper bound an the completion time of a Time Warp simulation. In our analysis, we consider the case of a simulation model with homogeneous logical processes, where "homogeneous" means they have the same average event routine time and the same state saving cost. Then we propose a methodology to determine when it is time-convenient to use a Time Warp synchronized simulation, instead of a sequential one, for a simulation model with features matching those considered in our analysis. We give an answer to this question without the need to preliminary generate the simulation code. Examples of methodology usage are reported for the case of both a synthetic benchmark and a real world model.

关键词： virtual time discrete event simulation Time Warp rollback-recovery parallel and distributed simulation performance evaluation

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