A number of library-based parallel and sequential network simulators have been designed. This paper describes a library, called GloMoSim (for Global Mobile system Simulator), for parallelsimulation of wireless networ...
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ISBN:
(纸本)0818684577
A number of library-based parallel and sequential network simulators have been designed. This paper describes a library, called GloMoSim (for Global Mobile system Simulator), for parallelsimulation of wireless networks. GloMoSim has been designed to be extensible and composable: the communication protocol stack for wireless networks is divided into a set of layers, each with its own API. Models of protocols at one layer interact with those at a lower (or higher) layer only via these APIs. The modular implementation enables consistent comparison of multiple protocols at a given layer. The parallel implementation of GloMoSim can be executed using a variety of conservative synchronization protocols, which include the null message and conditional event algorithms This paper describes the GloMoSim library, addresses a number of issues relevant to its parallelization, and presents a set of experimental results on the IBM 9076 SP, a distributed memory multi-computer. These experiments use models constructed from the library modules.
The implementation of a cloning mechanism that allows for the evaluation of multiple simulated futures is presented and its performance is analyzed. A running parallel discrete event simulation is dynamically cloned a...
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ISBN:
(纸本)0818684577
The implementation of a cloning mechanism that allows for the evaluation of multiple simulated futures is presented and its performance is analyzed. A running parallel discrete event simulation is dynamically cloned at decision points to explore different execution paths concurrently. Ita this way what-if and alternative scenario analysis in gaming, tactical and strategic applications can be evaluated interactively or non-interactively. Performance results show that virtual logical processes, a new mechanism developed to avoid repeating common computations among clones improves efficiency.
With the emerging of broadband networks based on ATM technology, performance evaluation tools that allow the study of large systems are desperately needed. In this article we present our experiments in distributed sim...
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ISBN:
(纸本)0818684577
With the emerging of broadband networks based on ATM technology, performance evaluation tools that allow the study of large systems are desperately needed. In this article we present our experiments in distributedsimulation of large and complex ATM network models with a conservative simulator. The goal here was not to achieve the maximum speedup with well-shaped topologies but rather to see what speedup can be obtained with a realistic model on a "state-of-the art" parallel computer. A network model with 78 switches is simulated on a Gray T3E using 3 different traffic loads. The performance results show that good speedups can be achieved but also highlight partitioning problems and bottlenecks in the simulation model that can seriously limit the speedup of realistic model simulations.
This paper presents a sparse state saving scheme for Time Warp parallel discrete event simulation. The scheme bases the selection of the states to be recorded on the event history of the logical processes. To this pur...
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ISBN:
(纸本)0818684577
This paper presents a sparse state saving scheme for Time Warp parallel discrete event simulation. The scheme bases the selection of the states to be recorded on the event history of the logical processes. To this purpose, statistics on the virtual time advancement of the processes are collected for the prediction of virtual time intervals that are likely to contain rollback points;the states corresponding to the starting point of those intervals are recorded as checkpoints in order to reduce the average coasting forward. The percentage of states to be recorded is defined by a parameter whose value is dynamically recalculated on the basis of the on-line observation of the variation of a checkpointing-rollback cost function. simulation results of synthetic workloads are presented for a performance comparison with previous schemes.
One of the main reasons why parallel discrete event simulation has not been adopted more widely in industry is that the terminology used by the parallelsimulation community differs from that of industrial simulation ...
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One of the main reasons why parallel discrete event simulation has not been adopted more widely in industry is that the terminology used by the parallelsimulation community differs from that of industrial simulation practitioners. This paper shows how the gap between these two communities can be bridged by presenting a methodology for automating the parallelization of manufacturing simulations. Our approach provides a way of automatically generating a mapping from a sequential simulation model to an efficient parallel implementation. The results of this mapping can be expressed in a form which is independent of any particular parallelsimulation system or language. Since it is easy to generate code for different simulation systems, it is possible to evaluate alternative parallelsimulation protocols at an early stage of development. A prediction of the performance can thus be obtained by studying the behaviour of an abstraction of the simulation model with various strategies or on different computing platforms.
The simulation of wireless systems such as cellular or personal communication systems comprises both discrete and continuous time processes. To accelerate these simulations, we propose the use of interval jumping, a n...
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The simulation of wireless systems such as cellular or personal communication systems comprises both discrete and continuous time processes. To accelerate these simulations, we propose the use of interval jumping, a novel technique that allows the execution of a continuous time model to proceed in irregularly sized jumps rather than in the traditional time-stepped manner. The foundations for this mechanism are laid out in the light of the simulation of a complex simulation model which includes radio propagation, channel allocation, transmitter power control and user mobility. We conclude with experimental results comparing sequential and parallel execution of these accelerated simulations which indicate the good potential of our technique.
Circuit simulation is a critical bottleneck in VLSI design. This paper describes the implementation of an existing parallel switch-level simulator called MIR-SIM on a shared-memory multiprocessor architecture. The sim...
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Circuit simulation is a critical bottleneck in VLSI design. This paper describes the implementation of an existing parallel switch-level simulator called MIR-SIM on a shared-memory multiprocessor architecture. The simulator uses a set of three different conservative protocols: the null message protocol, the conditional eyelet protocol and the accelerated null message protocol, a combinations of the preceding two algorithms. The paper describes the implementation of these protocols to exploit shared-memory features, measures their relative performance for a set of six benchmark circuits ranging in size from 3000 to almost 70,000 transistors, and compares the speedup obtained by each of the three protocols.
We describe the TED/C++ implementation of WIPPET, a parallelsimulation testbed for evaluating radio resource management algorithms and wireless transport protocols. Versions 0.3 and 0.4 of the testbed model radio pro...
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We describe the TED/C++ implementation of WIPPET, a parallelsimulation testbed for evaluating radio resource management algorithms and wireless transport protocols. Versions 0.3 and 0.4 of the testbed model radio propagation (long- and short-scale fading and interference) and protocols for integrated radio resource management in mobile wireless voice networks including the standards-based AMPS, NA-TDMA and GSM protocols, and several research-oriented protocol families. We provide parallel performance data verifying that the dominant computational demand due to received signal quality calculation can be partitioned geographically, by orthogonal radio channels, or in a hybrid manner.
We present a dynamic load balancing algorithm for parallel Discrete Event simulation of spatially explicit problems. In our simulations the space is discretized and divided into subareas each of which is simulated by ...
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We present a dynamic load balancing algorithm for parallel Discrete Event simulation of spatially explicit problems. In our simulations the space is discretized and divided into subareas each of which is simulated by a Logical Process (LP). Load predictions are done based on the future events that are scheduled for a given LP. The information about the load of the processes is gathered and distributed during the Global Virtual Time calculation. Each LP calculates the new load distribution of the system. The load is then balanced by moving spatial data between neighboring LPs in one round of communications. In our problems, the LPs should described as being elements of a ring from the point of view of communication. Due to the spatial characteristics, the load can be migrated only between neighboring LPs. We present an algorithm that performs the load balancing in a ring and minimizes the maximum after-balance load.
In this paper the performance of the Chandy-Misra algorithm in distributedsimulation has been studied in the context of a particular simulation applications a cellular network. The logical process structure under the...
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ISBN:
(纸本)0818684577
In this paper the performance of the Chandy-Misra algorithm in distributedsimulation has been studied in the context of a particular simulation applications a cellular network. The logical process structure under the algorithm is modified in such a way that the excessive synchronisation caused by the algorithm can be avoided. The synchronisation is minimised by reducing the number of connections between logical processes (LP). The concept of a neighbourhood of an LP is defined in such way that an LP is connected via logical channels only to those LPs that belong to its neighbourhood. A broadcast messages method is proposed to solve the communication between non-connected logical processes, i.e. those outside the neighbourhood. simulation experiments are carried out in a previously implemented distributedsimulation environment, Diworse. A GSM network is used as a simulation application where target of the simulation is to obtain estimates for the channel utilisation. Carrier per interference (C/I) values for GSM channels are used for determining the need for handovers. Execution time of the simulation and deviations in the C/I values are measured for completely connected and broadcast message methods in order to find but the effect of connection reduction. The results indicate that the broadcast messages method enables significantly faster simulation. With the GSM application the proposed method has only a negligible distorting effect to the simulation.
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