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下一代网络的发展是为用户提供无处不在的移动通信网络,使用户对其定制业务的体验始终如一,这就需要为用户提供不同网络之间尽可能小的切换时延。文中采用OPNET Modeler仿真软件,对紧耦合结构下通用移动通信系统(UMTS)到无线局域网(WLAN)的切换协议进行仿真。以地铁站为场景,设计考虑通用移动通信系统(UMTS)与无线局域网(WLAN)间的切换,对比紧耦合结构与松耦合结构下的切换时延,说明网络结构的耦合度越高,切换的时延就越小。 相似文献
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蔡家麟 《光纤与电缆及其应用技术》1996,(1):3-7
本文对适用于总线网络的两种局域网综合话音/数据协议的吞吐量及话音分组时延性能进行了理论及计算机仿真研究。该研究成果对综合业务局域网设计具有实用参考价值。 相似文献
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QoS Routing for Mesh-Based Wireless LANs 总被引:1,自引:0,他引:1
Wireless LANs with their increased data rate become an attractive technology for connecting mobile users to the Internet. Efficient deployment of wireless LANs will require the ability to extend the wireless LANs coverage without the need to deploy a very large number of access points. Mesh-based wireless LANs are an attractive solution to this problem. These networks extend wireless LAN coverage by using each node in the network as a router, resulting in a multihop topology. In this paper we introduce a novel routing algorithm, wireless mesh routing (WMR), that provides quality-of-service (QoS) support and accounts for the characteristics of both infrastructure-based wireless LANs and ad hoc networks. The algorithm is validated using the OPNET modeler. The simulation results show that the mesh network using WMR protocol can provide QoS support and react dynamically to the network status changes with low control overheads. Using the proposed software architecture the proposed routing protocol can be implemented with any MAC protocol, resulting in easy implementation in existing wireless nodes. 相似文献
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对传统计算机局域网络技术进行较为详细的阐述,并针对现有计算机技术、通信技术和多媒体技术的发展对计算机局域网络技术的发展趋势进行详细的综述,如交换式LAN、ATM LAN和交换式互连网络设备。 相似文献
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网络仿真技术是一种反映和预测网络性能的科学手段。仿真软件提供了真实网络和仿真器交互的方法,在不同条件下对网络进行模拟,并分析设计方案的可行性和健壮性。介绍了OPNET仿真软件的主要特性、建模机制及仿真步骤,重点论述了OPNET的网络域、节点域、进程域的建模过程和建模方法,并结合一个包交换网络的实例进行了仿真,通过对比链路平均利用率、网络吞吐量和端对端延迟在不同包产生速率时的变化,阐述了OPNET在具体网络规划和设计中的应用。 相似文献
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为保障安全,局域网和互联网经常并不直接相连甚至物理隔离,但这并不能彻底解决局域网络的安全问题。局域网络面临着内部攻击、“摆渡”攻击、非法外联以及非法接入等安全威胁。局域网安全防范的措施与方法主要包括:加强系统认证方式的安全,防止非授权访问;安装主机防火墙,防范网络内部攻击;加强涉密信息介质的管理和使用;加密存储、传输涉密信息以及及时更新安全补丁,保持系统和应用软件的安全。 相似文献
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A common communications convergence scenario which is being adopted in personal communications relates to the combination
of wireless and cellular networks by the use of multimode terminals. Since most of the wireless networks were initially dimensioned
only for data communications, this paper shows how voice over wireless LAN dimensioning could be addressed under the optimal
network throughput and the perspective of voice quality, using a simple approach. The maximum number of simultaneous users
resulting from throughput is limited by the collisions taking place in the shared medium with the statistical contention protocol.
The voice quality is conditioned by the delay and the packet loss in the contention protocol. Both approaches are analyzed
within the scope of the voice codecs commonly used in voice over wireless LANs, to conclude that voice dimensioning based
on network throughput and voice quality show complementary results. Additionally the use of low rate codecs in voice over
wireless LANs is advantageous for the network performance point of view but may produce poor voice quality results. Mid range
codecs like G729 could represent a trade-off for quality throughput. For these reasons, voice quality and wireless network
throughput have to be taken into account in the network admission control, design and deployment to ensure a satisfactory
user experience. The impact of handoff interval of wireless convergent networks on the conversation quality need also be assessed
for a proper network design. 相似文献
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基于OPNET的IPSec VPN的性能分析 总被引:1,自引:1,他引:0
采用OPNET仿真软件对网络性能进行仿真与分析,既可以减少统在网络设计、性能研究及开发的费用,提高网络设计的效率,又使得数据统计与分析变得非常容易。文章主要论述了网络仿真的流程、建模的方法,并通过实验利用OPNET软件对IPv6环境下IPSecVPN的性能作出详细的分析。 相似文献
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The last decade has witnessed tremendous productivity in the field of local area networks (LANs). The productivity has ranged from many different available commercial LANs to detailed technical analyses, performance evaluation models and simulation results. The need now arises for networks to teach students in university and engineers in industry how to build and design LANs. The purpose of this paper is to present the Ed-Net; a multi-protocol local area network for educational and design purposes. The network uses available VLSI chips that implement LAN protocols. The intelligent co-processors LAN controllers such as INTEL 82586 for the Ethernet and Western Digital WD 2840 for the token-passing are used. Also advanced encoder/decoder chips such as Seeq 8023 and Harris HD-6409 are utilized. Ed-Net can be configured as an Ethernet, or a tokenpassing bus. Number of experiments can be run on the network. These experiments range from: interfacing the main CPU to the LAN controller, memory sharing, FIFO and DMA operation, error detection, and synchronization to framing, data encryption and successful transmission and reception. 相似文献