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无线网络物理层精确建模与仿真方法研究 总被引:1,自引:0,他引:1
无线网络仿真中,上层通信协议仿真的精确性,在很大程度上取决于仿真系统能否对物理层进行精确的建模与仿真,然而现有网络仿真工具OPNET物理层的仿真精度,不能完全满足无线网络仿真实验的要求。针对OPNET中无线信道不真实、数据包收发模型较粗糙等影响物理层仿真精度的突出问题,结合物理层工作的基本原理,本文提出了相应的改进方法。该方法对OPNET物理信道模型、收发信机工作模式、数据包误帧率计算方法等方面,进行了优化与完善。仿真结果表明,该方法可以显著提高OPNET管道机制对无线网络物理层仿真的精度。 相似文献
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基于OPNET的卫星网络仿真平台设计 总被引:2,自引:2,他引:0
卫星网络采用无线信道进行通信,使得在仿真设计时存在一定的困难并且工作量较大。该文采用了一种近似方法,利用现有技术成熟的地面网络来模拟卫星网络。通过对通信链路定时通断及其属性的设置充分体现了卫星网络的移动性、动态性和传输时延大等特点。并用OPNET网络仿真软件建模并得到了仿真结果。此方法在仿真开发初期是一种切实可行的设计方法。 相似文献
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信道接入控制技术是实现无线网络节点共享无线信道空间的关键技术。IEEE802.11作为无线局域网的一个重要协议标准,定义了两种信道接入控制方式,分别是分布式协调方式和中心协调方式。本文主要研究了以IEEE802.11协议标准为对象的无线局域网两种信道接入技术的学习和讨论,并运用先进的网络仿真工具OPNET对信道接入技术进行了仿真研究,总结了不同信道接入技术下的无线局域网的网络性能。指出设计网络时需要根据不同情况来选用不同的方式来进行通信。 相似文献
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?? ???????????????? 《计算机工程》2007,33(8):208-123
网络仿真在自组网开发过程中评估新的协议性能的基本技术, 该文介绍了网络建模问题,比较了各种传统路由算法和自组网算法.讨论了自组网的确定性和不确定性建模,分析了NS、OPNET和MATLAB等几种仿真工具.基于不确定建模原理,使用MATLAB和C设计并实现了一个无线自组网路由仿真器. 相似文献
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能量有效性是无线传感器网络路由协议设计的重要目标。以典型的层次化路由协议LEACH为研究对象,利用OPNET对其进行建模,在OPNET虚拟无线环境下建立了LEACH协议的仿真平台,仿真了LEACH协议的实际运行情况,并以网络生命周期、节点能耗为指标得出LEACH协议能量有效性的结论。 相似文献
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IEEE 802.11无线局域网OPNET建模与性能测试 总被引:13,自引:0,他引:13
讨论了IEEE802.11无线局域网的建模和性能问题。基于对IEEE802.11协议和目前功能最强大的网络仿真工具OPNET软件的研究。首先分析了无线局域网的各种行为,分别对这些行为单独建模后,通过有线状态机将它们集成而形成IEEE802.11协议支持模块。给出了模型输入输出接口的详细说明。并对网络的性能进行了分析比较。 相似文献
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《Journal of Network and Computer Applications》2012,35(6):1691-1708
Recent advancements in wireless communication are creating a spectrum shortage problem on a daily basis. Recently, Cognitive Radio (CR), a novel technology, has attempted to minimize this problem by dynamically using the free spectrum in wireless communications and mobile computing. Cognitive radio networks (CRNs) can be formed using cognitive radios by extending the radio link features to network layer functions. The objective of CRN architecture is to improve the whole network operation to fulfil the user's demands anytime and anywhere, through accessing CRNs in a more efficient way, rather than by just linking spectral efficiency. CRNs are more flexible and exposed to wireless networks compared with other traditional radio networks. Hence, there are many security threats to CRNs, more so than other traditional radio environments. The unique characteristics of CRNs make security more challenging. Several crucial issues have not yet been investigated in the area of security for CRNs. A typical public key infrastructure (PKI) scheme which achieves secure routing and other purposes in typical ad hoc networks is not enough to guarantee the security of CRNs under limited communication and computation resources. However, there has been increasing research attention on security threats caused specifically by CR techniques and special characteristics of CR in CRNs. Therefore, in this research, a survey of CRNs and their architectures and security issues has been carried out in a broad way in this paper. 相似文献
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Cognitive radio technology, a revolutionary communication paradigm that can utilize the existing wireless spectrum resources more efficiently, has been receiving a growing attention in recent years. As network users need to adapt their operating parameters to the dynamic environment, who may pursue different goals, traditional spectrum sharing approaches based on a fully cooperative, static, and centralized network environment are no longer applicable. Instead, game theory has been recognized as an important tool in studying, modeling, and analyzing the cognitive interaction process. In this tutorial survey, we introduce the most fundamental concepts of game theory, and explain in detail how these concepts can be leveraged in designing spectrum sharing protocols, with an emphasis on state-of-the-art research contributions in cognitive radio networking. Research challenges and future directions in game theoretic modeling approaches are also outlined. This tutorial survey provides a comprehensive treatment of game theory with important applications in cognitive radio networks, and will aid the design of efficient, self-enforcing, and distributed spectrum sharing schemes in future wireless networks. 相似文献
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Ad hoc网络综合了分组交换网和无线通信网两者的优点,是一种极有前途的无玑通信组网技术。在Ad hoc网络中,设计一个合适的MAC协议不仅可以确保在发生分组冲突时在移动台之间成功地交换信息,而且还可以提高系统吞吐量、减小分组传输时延。本文讨论了影响Ad hoc网络MAC协议性能的一些关键因素及其解决方案,并给出了对MAC技术进行建模分析时常用的一些基本假设和方法。 相似文献
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The research projects our investigations have spawned span topics in attack modeling, quantifying the effects of attacks on network performance and robustness, and the construction of computational tools for managing our simulation experiments. We hope, however, that our work's meta-contribution is to show, by proof of concept, that you must consider simple, sideways system attacks before you can rely on a system. We encourage engineers of mission-critical systems to look for then cavemen (or squirrels) and to study carefully what actions these adversaries might take against the products they roll out. In this paper we examine simple attacks on routing protocols for wireless networks. In our study, the system was to be a wireless ad hoc network, a collection of independent, possibly mobile computing devices that communicate using radio frequency technology. 相似文献
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Cognitive radio networks have recently attracted significant research attention owing to their promise for application in future cellular communication. In this light, given the intense power consumption of wireless networks, considerable research is now being directed at designing random cognitive radio networks with enhanced energy efficiency. In this study, we investigate the outage probability and energy efficiency in a cognitive radio network, modeling the locations of the primary users and cognitive users as a Poisson point process. We derive closed-form expressions for the outage probability and energy efficiency with consideration of the probabilities of unoccupied (not utilized by the primary users) channel selection and successful transmission for imperfect detection in an interference-limited environment of cognitive radio network. Furthermore, we propose a transmit antenna selection method for the cognitive transmitter in such networks and accordingly develop closed-form expressions for the outage probability and energy efficiency. The study reported here highlights the importance of combining the capabilities of unoccupied channel selection and successful transmission in cognitive radio networks to achieve optimal performance regarding outage probability and energy efficiency. In terms of energy efficiency, there is an optimal threshold that maximizes the energy efficiency. For implementation in transmit antenna selection, the outage probability can be significantly decreased by increasing the number of transmit antennas, even though the energy efficiency is maximized at the target outage probability. 相似文献
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无线传感器网络(WSNs)监测数据的收集方式方法是目前的研究热点,而无线传输的广播特性又使得网络编码非常适合于无线网络。在介绍网络编码原理、核心思想以及在WSNs应用现状的基础上,提出了一种基于部分网络编码的自适应WSNs数据收集方法,该方法针对簇网络拓扑结构,簇成员节点把网络编码数据发送给簇头节点,簇头节点利用随机网络编码的方式把数据传输到Sink节点。实验结果表明:该机制具有能耗较低和汇报数据较准确的特点。 相似文献
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无线通信网络的发展趋势之一是将各种不同无线接入技术进行融合。多接入选择作为无线资源管理中的关键技术是目前异构网融合的研究热点之一。从用户的利益出发,充分考虑预接入网络的费用、QoS和稳定性;假定不同的网络运营商之间是彼此竞争的,即没有达成统一的协议,提出了一种结合目标代价函数与层次分析法的动态多接入选择算法。通过对影响因素进行分析和二次判断,建立了网络选择决策模型,仿真结果验证了该算法的正确性与有效性。 相似文献
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Mohsin Iftikhar Bjorn Landfeldt Sherali Zeadally Albert Zomaya 《Pervasive and Mobile Computing》2011,7(5):525-544
We are currently witnessing a growing interest of network operators to migrate their existing 2G/3G networks to 4G technologies such as long-term evolution (LTE) to enhance the user experience and service opportunities in terms of providing multi-megabit bandwidth, more efficient use of radio networks, latency reduction, and improved mobility. Along with this, there is a strong deployment of packet data networks such as those based on IEEE 802.11 and 802.16 standards. Mobile devices are having increased capabilities to access many of these wireless networks types at the same time. Reinforcing quality of service (QoS) in 4G wireless networks will be a major challenge because of varying bit rates, channel characteristics, bandwidth allocation and global roaming support among heterogeneous wireless networks. As a mobile user moves across access networks, to the issue of mapping resource reservations between different networks to maintain QoS behavior becomes crucial. To support global roaming and interoperability across heterogeneous wireless networks, it is important for wireless network operators to negotiate service level agreement (SLA) contracts relevant to the QoS requirements. Wireless IP traffic modeling (in terms of providing assured QoS) is still immature because the majority of the existing work is merely based on the characterization of wireless IP traffic without investigating the behavior of queueing systems for such traffic. To overcome such limitations, we investigate SLA parameter negotiation among heterogeneous wireless network operators by focusing on traffic engineering and QoS together for 4G wireless networks. We present a novel mechanism that achieves service continuity through SLA parameter negotiation by using a translation matrix, which maps QoS parameters between different access networks. The SLA matrix composition is modeled analytically based on the G/M/1 queueing system. We evaluate the model using two different scheduling schemes and we derive closed form expressions for different QoS parameters for performance metrics such as packet delay and packet loss rate. We also develop a discrete event simulator and conduct a series of simulation experiments in order to understand the QoS behavior of corresponding traffic classes. 相似文献