无线传感器网络模拟器比较分析

针对可用于无线传感器网络的模拟器NS-2和OMNET 进行了分析对比,并给出了选择建议.文中定义了评价模拟器的6个指标参数,依次给出了在模拟传感器网络时这两个模拟器的功能和性能.通过对比这6个参数,认为OMNET 更加适合用来模拟无线传感器网络.     

无线传感器网络仿真模拟技术比较分析*

分析了仿真模拟技术在无线传感器网络研究领域的重要性,对现在比较流行的几种仿真模拟器的应用背景、设计思路、性能优缺点、使用时应注意的问题等进行了详细的分析,归纳总结出一个成熟的无线传感网络仿真模拟器应该具备的基本功能和特性,指出了今后的研究方向.     

基于ns的局域网上网络仿真环境的构建方法

1.引言网络模拟(Network Simulation)是网络协议开发人员在设计和评测网络协议时使用的重要方法。网络模拟提供一个可重复、易控制的试验环境,并且建立和运行的费用低。网络模拟将协议实现抽象成模型(即虚拟的协议实现),并将其放在虚拟的网络环境下观察。网络仿真(Network Emulation)是在网络模拟的基础上增加和真实网络的接口,实现真实网络和虚拟网络的交互。网络仿真可以看作网络模拟器和真实协议实现的混合体。仿真器内部简化的协议实现提供了接收、处理和产生真实网络报文的能力;转化装置介于真实网络和仿真器之间、它能够将真实网络报文转换为模拟报文.也可以将模拟报文转换为真实网络报文,从而使得仿真器内部的协议     

基于CUDA和电子海图模拟雷达岸线回波的方法

雷达回波信号的仿真是雷达模拟器模拟显示逼真与否的基础,在此背景下提出利用电子海图和CUDA并行处理技术,模拟导航雷达海岸线回波的新方法.通过对电子海图的并行处理实现对导航雷达海岸线回波的模拟,仿真了雷达岸线回波的遮挡效果,解决了雷达模拟器回波生成实时性要求的难题.通过计算机仿真验证了该方法的有效性,已实际运用于某型雷达模拟器的回波信号仿真.     

基于幅频自校准的高精度LVDT模拟器设计

电路模拟LVDT传感器在航空发动机测试中有着广泛的应用,相对于机械传感器其降低了使用难度和维护费用;传统模拟器由于电路中变压器的影响,仿真精度较差导致系统测试准确性降低,研制高精度LVDT模拟器存在着较大的工程需求;文章从LVDT传感器工作原理出发,基于乘法型DAC芯片实现了电路合成模拟LVDT传感器;同时在模拟器中设计自动校准单元,利用离线拟合并存储到FPGA中的模板曲线对不同通道进行在线校准,消除了变压器幅频响应的影响,提高了模拟器在宽频率范围内的仿真精度;文章通过理论推导证明了模板曲线的有效性,通过测试数据验证了该模拟器在0.36~10 kHz范围内可达到优于0.1%的设计精度;该模拟器能够逼真模拟LVDT传感器的电气行为,已成功应用于某型号发动机控制系统的地面仿真测试平台中,达到了预期效果。     

NCTUns：一种新的网络模拟技术

NCTUns是由台湾交通大学研制的一种网络模拟与仿真软件.与NS2等常用的网络模拟软件相比较,NCTUns具有实验结果更逼真可信,能直接使用现有的一些网络软件从而减少设计实验环境的工作量等优点.分析了NCTUns网络模拟器的工作原理与仿真机制,介绍了模拟器的主要组成部分,然后详细阐述了NCTUns在设计和实现时采用的一些新的网络模拟技术和手段,最后在NCTUns中实验用户自己的模拟对象.     

一个基于TOSSIM的异构传感器网络仿真方案

TOSSIM提供了每一节点运行相同应用的传感器网络仿真实验方法,但很多传感器网络中各节点需要运行的应用各不相同.为了用TOSSIM仿真这类异构传感器网络,从结构上分析了TOSSIM不能仿真异构传感器网络的原因,通过拓展Main配件的StdControl接口,引入事件响应控制机制,从而解决了在TOSSIM的单线程仿真模式下不能直接仿真异构传感器网络的问题,并成功实现了多个异构传感器网络的TOSSIM仿真实验.仿真结果分析表明在TOSSIM中实现规模可扩展的异构传感器网络仿真实验是可能的.     

分布式计算平台中任务调度的模拟器研究

提出与描述一个分布式计算平台中任务调度的模拟器,该模拟器可以用来仿真与评测网络计算平台上的主-从模式的并行分布式应用.它采用任务跟踪的方式,周期性的收集任务相关的收据来实现.该模拟器支持多种运行场景、根据应用的需求来控制输入参数;能够完成不同任务调度策略分析与检查点文件共享策略分析.分析了两种类型的任务调度算法在模拟器上的仿真:FCFS(First Come First Served)策略和MinMax(unassigned min-max)策略.模拟与性能结果表明:该模拟器可以仿真因特网上的大规模分布式计算平台的调度策略与检查点策略对通信轮回时间的影响,是一种接近真实世界的仿真结果,方便了程序员的操作.     

一种新型雷达高度表回波信号模拟器的设计与实现

为了客观评估和测试雷达高度表的动态性能,提出了一种新的脉冲雷达高度表回波信号模拟器的设计思想和实现方法;该模拟器的创新点在于集成了雷达高度表回波信号的两种模拟方法:基于实际飞行试验采集回波的回放和基于数学模型的仿真回波;推导了回波仿真的数学模型,并基于现代仿真与软件无线电技术完成了模拟器的系统结构与各子模块的设计和实现;理论分析及测试结果表明该模拟器能在实验室条件下有效模拟飞行航迹中不同地形地貌条件下的真实地面散射回波.     

大型船舶联网设备网络模拟器软件设计

针对大型船舶的联网设备的网络特性,提出了一种用于研发联网设备网络协议和检测网络运行状态的模拟器设计方案。该方案采用PC104作为硬件架构,在Linux平台上使用面向对象技术对各联网设备的网络特性进行建模,实现对各联网设备网络特性的模拟;并采用编写脚本文件的方法增强了模拟器的仿真灵活性和软件扩展能力。该模拟器构建的网络实验平台,能够加快联网设备和网络协议的研发速度、检测网络性能和降低开发费用。     

Enabling iterative development and reproducible evaluation of network protocols

Over the last two decades several efforts have been made to provide adequate experimental environments, aiming to ease the development of new network protocols and applications. These environments range from network simulators providing a highly controllable evaluation conditions, to live testbeds providing realistic evaluation environment. While these different approaches foster network development in different ways, there is no simple way to gradually transit from one to another, or to combine their strengths to suit particular evaluation needs. We believe that enabling a gradual transition from a pure simulated environment to a pure realistic one, where the researcher can decide which aspects of the environment are realistic and which are controllable, allows improving network solutions by simplifying the problem analysis and resolution.In this paper, we propose a new network experimentation framework where simulated and real components can be arbitrarily combined to build custom test environments, allowing refining and improving new protocols and applications implementations by gradually increasing the level of realism of the evaluation environment. Moreover, we present a testbed architecture specifically adapted to support the proposed concept, and discuss the design choices we made based on our previous experience in the area of network testbeds. These choices address key issues in network testbed development, such as ease of experimentation, experiment reproducibility, and testbed federation, to enable scaling the size of experiments beyond what a single testbed would allow.     

Open-source simulators for Cloud computing: Comparative study and challenging issues

Resource scheduling in infrastructure as a service (IaaS) is one of the keys for large-scale Cloud applications. Extensive research on all issues in real environment is extremely difficult because it requires developers to consider network infrastructure and the environment, which may be beyond the control. In addition, the network conditions cannot be controlled or predicted. Performance evaluations of workload models and Cloud provisioning algorithms in a repeatable manner under different configurations are difficult. Therefore, simulators are developed. To understand and apply better the state-of-the-art of Cloud computing simulators, and to improve them, we study four known open-source simulators. They are compared in terms of architecture, modeling elements, simulation process, performance metrics and scalability in performance. Finally, a few challenging issues as future research trends are outlined.     

飞行模拟器联网组训系统的构建

介绍了某型飞机飞行模拟器联网组训系统的基本组成,并给出了其构建方法.采用Client/Server网络通信模式和TCP/IP通信协议,在Visual C--+6.0环境下利用Windows Socket网络编程,实现了多台飞行模拟器间的数据通信.应用实践证明,该系统性能稳定,操作、维护方便,实时性好,扩展性强,能够适应...     

Evolutionary design and behavior analysis of neuromodulatory neural networks for mobile robots control

Evolutionary Robotics (ER) is one of promising approaches to design robot controllers which essentially have complicated and/or complex properties. In most ER research, the sensory–motor mappings of robots are represented as artificial neural networks, and their connection weights (and sometimes the structure of the networks) can be optimized in the parameter spaces by using evolutionary computation. However, generally, the evolved neural controllers could be fragile in unexperienced environments, especially in real worlds, because the evolutionary optimization processes would be executed in idealized simulators. This is known as the gap problem between the simulated and real worlds. To overcome this, the author focused on evolving an on-line learning ability instead of weight parameters in a simulated environment. According to recent biological findings, actually, the kinds of on-line adaptation abilities can be found in real nervous systems of insects and crustaceans, and it is also known that a variety of neuromodulators (NMs) play crucial roles to regulate the network characteristics (i.e. activating/blocking/changing of synaptic connections). Based on this, a neuromodulatory neural network model was proposed and it was utilized as a mobile robot controller. In the paper, the detail behavior analysis of the evolved neuromodulatory neural network is also discussed.     

A real-time network simulation infrastructure based on OpenVPN

We present an open and flexible software infrastructure that embeds physical hosts in a simulated network. In real-time network simulation, where real-world implementations of distributed applications and network services can run together with the network simulator that operates in real-time, real network packets are injected into the simulation system and subject to the simulated network conditions computed as a result of both real and virtual traffic traversing the network and competing for network resources. Our real-time simulation infrastructure has been implemented based on Open Virtual Private Network (OpenVPN), modified and customized to bridges traffic between the physical hosts and the simulated network. We identify the performance advantages and limitations of our approach via a set of experiments. We also present two interesting application scenarios to show the capabilities of the real-time simulation infrastructure.     

A Generic Virtual Bus for Hardware Simulator Composition

The typical interface between hardware components is a standardized bus. This article presents a virtual counterpart for simulated hardware components: a virtual bus on a virtual motherboard. The authors show that reuse of standard components, common with real hardware, can find its analogy in the domain of simulated hardware, making simulators less expensive and more flexible.     

网络模拟软件NS2与OPNET的剖析比较①

NS2和OPNET是目前主流的网络模拟软件,为深入地剖析比较它们的特点及差别以供学习和选用时参考,从软件技术、使用方法和引擎性能三个方面进行了详细对比分析。在软件技术方面分别从体系结构、支持的网络技术、网络设备模型库和软件可扩展性上进行分析比较;在模拟器引擎性能方面,通过在相同模拟条件下,选取内存消耗和CPU运算时间两个指标,针对不同规模的抽象网络,分别对OPN盯和NS2的引擎性能进行了对比实验。结果表明,OPNET具有商业软件的优势,在用户友好性、模拟速度、内存消耗等方面优于NS2,而NS2则在开源和易扩展性方面优于OPNET,适合于模拟中小型网络。     

CASiNO: component architecture for simulating network objects

We describe the Component Architecture for Simulating Network Objects (CASiNO) useful for the implementation of communication protocol stacks and network simulators. This framework implements a rich, modular coarse‐grained dataflow architecture, with an interface to a reactor kernel that manages the application's handlers for asynchronous I/O, real timers and custom interrupts. These features enable developers to write applications that are driven by both data flow and asynchronous event delivery, while allowing them to keep these two functionalities distinct. We provide an example program and expository comments on the program to illustrate the use of the CASiNO framework. Published in 2002 by John Wiley & Sons, Ltd.     

Experiences with component‐oriented technologies in nuclear power plant simulators

This paper proposes the application of modern component‐oriented technologies to the development of nuclear power plant simulators. On the one hand, as a significant improvement on previous simulators, the new kernel is based on the Common Component Architecture (CCA). The use of such a high‐performance computing oriented component technology, together with a novel algorithm to automatically resolve simulation data dependencies, allows the efficient execution of both parallel and sequential simulation models. On the other hand, RT‐CORBA is employed in the development of the rest of the applications that comprise the simulator. This real‐time communication middleware not only makes the management of communications easier, but also provides the applications with real‐time capabilities. Software components used in these two ways, simulation models integrating the kernel and distributed applications from which the simulator is comprised, improve the evolution and maintenance of the entire system, as well as promoting code reusability in other projects. Copyright © 2006 John Wiley & Sons, Ltd.     

EMPOWER: a cluster architecture supporting network emulation

Network research generally requires a simulation or emulation environment to test protocol implementations, to evaluate the performance of a scheme or a system, and to study complicated and highly varying network operations. For large network simulation, simulators consume a large amount of time and memory; and its result is largely based on some modeling assumptions that may not hold in the real world. Emulators are difficult to scale for large network emulation because of the high cost of equipment if a one-to-one mapping scheme is employed. Otherwise, the target network has to be abstracted to a single router modeled with some performance metrics. We present a distributed IP network emulator cluster EMPOWER, which not only can be used to emulate a large network with a limited number of commodity computers, but also can generate user-defined arbitrary network conditions and traffic dynamics at packet level for specific test scenarios. EMPOWER is highly scalable in that each emulator node could be configured to emulate multiple network nodes, and the increment of the number of emulator nodes does not affect emulation validity. Some significant research issues such as network mapping and mobile wireless network emulation are discussed and addressed. Preliminary emulation results show that EMPOWER is capable of assisting the study of both wireline and wireless network protocols and applications.