In MANETs, majority of performance studies arc, carried out via simulations, where node mobility and radio propagation models play a crucial role. However;popular simulation tools, like NS-2 [1] and GloMoSint [2], use...
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ISBN:
(纸本)0769526977
In MANETs, majority of performance studies arc, carried out via simulations, where node mobility and radio propagation models play a crucial role. However;popular simulation tools, like NS-2 [1] and GloMoSint [2], use simplistic random mobility patterns and free space radio propagation models. Such simplification ignores many crucial details in environment where movements are not random and obstacles arc, common. To have a better understanding (of MANET protocols, there is a need,for a tool that can generate more realistic mobility), scenarios and provide better radio propagation model. This paper presents EGRESS, which is built on top of NS-2 and consists of two major components: SGT and ORPM. SGT is a tool that generates node movements in an urban environment with buildings and pathways. ORPM is an obstructive radio propagation model, which enhances the existing radio models in NS-2 by, taking into account obstacles in a 3D environment. We believe EGRESS is the first open source tool that provides such integrated and more realistic features for simulating urban environment. Our simulation results show that using more realistic scenarios can have a significant impact on network topology and performance of routing protocols.
The proceedings contain 20 papers. The topics discussed include: rendering on demand;an application of scalable massive model interaction using shared-memory systems;accelerating the irradiance cache through parallel ...
ISBN:
(纸本)3905673401
The proceedings contain 20 papers. The topics discussed include: rendering on demand;an application of scalable massive model interaction using shared-memory systems;accelerating the irradiance cache through parallel component-based rendering;parallelsimulation of cloth on distributed memory architectures;dynamic load balancing for parallel volume rendering;interactive volume rendering of unstructured grids with time-varying scalar fields;optimized volume raycasting for graphics-hardware-based cluster systems;accelerated volume rendering with homogeneous region encoding using extended anisotropic chessboard distance on GPU;parallel texture-based vector field visualization on curved surfaces using GPU cluster computers;and distributed force-directed graph layout and visualization.
Data Distribution Management (DDM) plays a key role in traffic volume control of large-scale distributedsimulations. In recent years, several solutions have been devised to make DDM more efficient and adaptive to dif...
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ISBN:
(纸本)0769526977
Data Distribution Management (DDM) plays a key role in traffic volume control of large-scale distributedsimulations. In recent years, several solutions have been devised to make DDM more efficient and adaptive to different traffic conditions. Examples of such systems include Region-Based, Fixed Grid-Based, Hybrid, and Dynamic Grid-Based (DGB) schemes. However, less effort has been made to improve the processing performance of DDM techniques. This paper presents a novel DDM scheme called the Adaptive Dynamic Grid-Based (ADGB) scheme that optimizes DDM time through analysis of Matching performance. ADGB uses an advertising scheme in which information about the target cell involved in the process of matching subscribers to publishers is known in advance. An important concept known as Distribution Rate (DR) is devised. DR represents the relative processing load and traffic volume generated at each federate. The Matching performance and DR are used as part of the ADGB method to select, throughout the simulation, the devised. advertisement scheme that achieves maximum gain with acceptable network traffic overhead. Performance estimation and analysis of ADGB have shown that given an ideal Matching probability, an efficiency gain of a maximum of 66% over the DGB scheme can be achieved. The novelty of the ADGB scheme is its focus on improving peirformance, an important (and often forgotten) goal of DDM strategies.
Collaboration within a distributed Interactive Application (DIA) requires that a high level of consistency be maintained between remote hosts. However, this can require large amounts of network-resources, which can ne...
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ISBN:
(纸本)0769526977
Collaboration within a distributed Interactive Application (DIA) requires that a high level of consistency be maintained between remote hosts. However, this can require large amounts of network-resources, which can negatively affect the scalability of the application, and also increase network, latency. Predictive models, such as dead reckoning, provide a sufficient level of consistency, whilst reducing network-requirements. Dead reckoning traditionally uses a spatial error threshold metric to operate. In previous work, it was shown how the use of the spatial threshold could result in potentially unbounded local absolute inconsistency. To remedy this, a novel time-space threshold was proposed, that placed bounds on local absolute inconsistency. However, use of the time-space threshold could result in. unacceptably large spatial inconsistency. A hybrid approach that combined both error threshold measures was then shown to place bounds on both levels of inconsistency. However, choosing suitable threshold values for use within the hybrid scheme has been problematic, as no direct comparisons can be made between the two threshold metrics. In this paper, a novel comparison scheme is proposed. Under this approach, an error threshold look-up table is generated, based on entity speed and equivalent inconsistency measures. Using this look-lip table, it is shown how the performance of comparable thresholds is equal on average,from the point of view of network, packet generation. These error thresholds are then employed in a hybrid threshold scheme, which is shown to improve overall consistency, in comparison to the previous solution of simply using numerically equal threshold values.
When using statechart diagrams, the history mechanism can be useful for modelling the suspension of a "normal" business process upon certain "abnormal" events together with the subsequent resumptio...
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ISBN:
(纸本)9789728865498
When using statechart diagrams, the history mechanism can be useful for modelling the suspension of a "normal" business process upon certain "abnormal" events together with the subsequent resumption, as illustrated by the examples in this paper. However, previous approaches to model checking statechart diagrams often ignore the history mechanism. We enhanced such a previous approach based on Communicating Sequential Processes (CSP) and developed a support tool for it.
The vision of grid computing is to make computational power, storage capacity, data and applications available to users as readily as electricity and other utilities. Grid infrastructures and applications have traditi...
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ISBN:
(纸本)0769526977
The vision of grid computing is to make computational power, storage capacity, data and applications available to users as readily as electricity and other utilities. Grid infrastructures and applications have traditionally been geared towards dedicated, centralized, high performance clusters running on UNIX flavour operating Systems (commonly referres to as cluster-based grid computing). This can be contrasted with desktop-based grid computing which refers to the aggregation of non-dedicated, de-centralized, commodity PCs connected through a network and running (mostly) the Microsoft Windows (TM) operating system. Large scale adoption of such Windows (TM)-based grid infrastructure may be facilitated via grid-enabling existing Windows applications. This paper presents the WinGrid (TM) approach to grid enabling existing Windows (TM)-based Commercial-Off-The-Shelf (COTS) simulation packages (CSPs). Through the use of a case study developed in conjunction with Ford Motor Company, the paper demonstrates how experimentation with the CSP Witness (TM) and FIRST can achieve a linear speedup when WinGrid (TM) is used to harness idle PC computing, resources. This, combined with the lessons learned from the case study, has encouraged us to develop the web set-vice extensions to WinGrid (TM). It is hoped that this would facilitate wider acceptance of WinGrid (TM) among enterprises having stringent security policies in place.
A symbiotic or online simulation is defined as one that interacts with the physical system in a mutually beneficial way. The simulation is driven by real time data collected from a physical system under control and ne...
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The proceedings contain 48 papers. The topics discussed include: reconfigurable platform for digital convergence terminals;European research in embedded systems;interface overheads in embedded multimedia software;auto...
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ISBN:
(纸本)3540364102
The proceedings contain 48 papers. The topics discussed include: reconfigurable platform for digital convergence terminals;European research in embedded systems;interface overheads in embedded multimedia software;automated distribution of UML 2.0 designed applications to a configurable multiprocessor platform;key research challenges for successfully applying MDD within real-time embedded software development;domain-specific modeling of power aware distributed real-time embedded systems;mining dynamic document spaces with massively parallel embedded processors;designing wireless sensor nodes;design, implementation, and experiment on outdoor deployment of wireless sensor network for environmental monitoring;energy-driven partitioning of signal processing algorithms in sensor networks;security in wireless sensor networks: considerations and experiments;on security of PAN wireless systems;and code size reduction by compiler tuning.
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