Δt. In this paper, we also discuss a suitable HLA based time management mechanism to implement DTSS on a distributed computing environment. In the performance evaluation of DTSS, the calculation cost of DTSS is implemented by using the HLA suitable time management mechanism. The results show that DTSS can be executed within the ideal time plus its 1% over-cost when a basic scenario of war-game simulation is employed. Therefore if the ratio of SoD to the total simulation is small, the execution time is expected to decrease to nearly this ratio. We also introduce the criterion for determining when DTSS is superior to the conventional method by using the performance evaluation results. The results presented in this paper are effectively utilized when DTSS is applied to practical applications." />

Event-Aware Dynamic Time Step Synchronization Method for Distributed Moving Object Simulation

Atsuo OZAKI
Masashi SHIRAISHI
Shusuke WATANABE
Minoru MIYAZAWA
Masakazu FURUICHI
Hiroyuki SATO

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E89-A    No.11    pp.3175-3184
Publication Date: 2006/11/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e89-a.11.3175
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Concurrent/Hybrid Systems: Theory and Applications)
Category: 
Keyword: 
parallel and distributed simulation,  distributed time management,  time step,  event based,  moving object,  real world simulation,  

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Summary: 
In computer simulation of a large number of moving objects (MOs), how to enlarge Δt (the interval between the simulation time steps) without introducing causality errors is one of the primary keys to enhancing performance. Causality errors can be avoided by using the same Δt among related MOs when they are in the scene of detection (SoD). But in a large-scale MO simulation, MOs interact with one another in a complicated manner requiring a large calculation cost to predict the beginning time of SoD. In this paper we propose an event-aware dynamic time step synchronization method (DTSS) for distributed MO simulation, which increases Δt without introducing causality errors and speeds up the simulation. DTSS can be implemented with little calculation cost because: (1) DTSS does not calculate the beginning time of SoD exactly, but calculates the time for possible entry into SoD with a simple mechanisim, and (2) MO simulation consists of a "movement"-phase and a "detection"-phase in which the distance-calculation between MOs requires a heavy load, and DTSS utilizes the distance values to calculate Δt. In this paper, we also discuss a suitable HLA based time management mechanism to implement DTSS on a distributed computing environment. In the performance evaluation of DTSS, the calculation cost of DTSS is implemented by using the HLA suitable time management mechanism. The results show that DTSS can be executed within the ideal time plus its 1% over-cost when a basic scenario of war-game simulation is employed. Therefore if the ratio of SoD to the total simulation is small, the execution time is expected to decrease to nearly this ratio. We also introduce the criterion for determining when DTSS is superior to the conventional method by using the performance evaluation results. The results presented in this paper are effectively utilized when DTSS is applied to practical applications.

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