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《电子科技文摘》2000,(12)
Y2000-62411-1484 0020700全球广播服务数据映象程序:Ka 频带线路应用 ITU气象数据的世界可存性模拟=GBS data mapper:mod-eling worldwide availability of ka-band links using ITUweather data[会,英]/Fitzgerald,G.& gostrom,G.//1999 IEEE MILCOM,Vol.2.—1484~1489(HC)0020701基于保护环的 ATM 多播树自愈机制[刊]/郭俊能//电子学报.—2000,28(7).—19~22,15(K)本文提出了一种采用预设计的方法生成可恢复ATM 多播树的自愈机制,该机制考虑了多播树的任何单链路和单节点失效两种情况。多播树的所有链路都包含在不同的保护环中。点相邻的保护环通过不经过公共点的接通路径相连。节点检测到失效时,只需激 相似文献
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在数据交换网络中,颜色树是一种通过节点不相交的多路径路由数据报文的有效方法。这种方法中组建两棵以某一节点为根节点的颜色树,即Red树和Blue树,网络中各节点到根节点的路径是节点不相交的。本文在分析和研究SimCT算法的基础上,提出了一种基于颜色树的多播树生成方法及单节点/链路故障的多播通信恢复方案。该方法根据SimCT算法构造的颜色树来组建一棵多播转发树,在多播树中单节点或单链路故障后,故障检测节点本地执行故障恢复方案,将受影响的故障节点的下游子树重新连接到多播树。仿真实验表明,本文所提出的多播树生成方案相比现有方案可以减少网络资源的浪费,并且故障恢复后的代价与原多播通信树相当。 相似文献
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本文主要研讨了具有QoS约束的动态多播路由问题.文中描述了一种适用于QoS多播路由的网络模型,提出了一种动态QoS多播路由协议(DQMRP),该协议能操作在单播路由协议的顶层,它只要求网络链路(或节点)的局部状态信息,不需要维护全局状态信息.DQMRP可有效地减少构造一棵多播树的开销,多播组成员可动态地加入/退出多播会晤.该协议可搜索多条可行树枝,并能选择一条最优(或近优)树枝将新成员连接到多播树.文中给出了DQMRP的正确性证明和复杂性分析,并通过仿真实验验证了该协议的可用性和有效性. 相似文献
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针对WDM光网络中单链路失效的情况,提出了一种基于链路的保护动态组播业务的优化共享保护算法(Link-based optimized shared-protection algorithm for multicast sessions,LB-OSPM).该算法在对工作树任意光纤链路失效情况寻找保护路径时,允许组播内不同保护路径共享预留波长资源,同时通过引入预留波长使用情况矩阵和波长预留矩阵记录预留波长资源的使用情况,实现了不发生冲突的不同组播的保护链路间共享预留波长资源.研究采用欧洲光网络(European Optical Network,EON)的拓扑对不同波长资源配置和网络负载情况下LB-OSPM算法的网络连接阻塞率做了仿真.结果表明,通过引入共享机制,LB-OSPM算法在对单链路失效保证100%恢复率的同时可以获得更低的连接阻塞率,提高了波长资源利用效率. 相似文献
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为无线单播模式设计的RTS/CTS信道握手机制不适用于多播模式,导致Ad hoc多播树节点易与隐藏终端发生冲突.通过提出m阶冲突域、节点在冲突域中的分布指标,结合无线网多播数据通信机制分析树节点所在m阶冲突域的冲突概率,进而得到节点自分布最优树的概念,并将它融入多播树的适应函数的设计中,淘汰不良树,优化树节点在m阶冲突域中的分布,在网络层形成一种预防机制,可降低隐藏终端冲突概率;应用于MAODV协议中,提高了MAODV的端到端数据分组平均投递率,这也能够为基于网的和混合式的其他类型MANETs多播路由协议的路由节点分布优化提供有价值的参考. 相似文献
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基于Logistic型混沌序列及Chebyshev型混沌序列构造出一种新的复合型混沌序列。对该复合型混沌序列的初值敏感性和复杂度等混沌性质以及平衡性、相关性等扩频性能进行了仿真研究。仿真结果表明,该复合型混沌序列有着更强的初值敏感性和更高的复杂度;除此之外,该复合型混沌序列在平衡性、自相关、互相关方面性能不仅优于原混沌序列,而且与应用在GPS系统中的P码相比,在相关性性能方面也有优势。本文提出一种序列优选方式,通过该优选方法选出的复合型混沌序列数目比Logistic型和Chebyshev型混沌序列的优选序列数分别多出31%和67%。该复合型混沌序列是一种安全性高,扩频性能优良,生成简单,序列数目众的扩频码片。 相似文献
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The optimization of the length of test sequences for finite state machine based protocol conformance testing is studied. The study focuses on test generation methods, called D-methods, that utilize distinguishing sequences in the construction of test segments. The extent of the optimization of the length of a test sequence is investigated with respect to two cases. The first case establishes the lower bound for the length of test sequences generated by any D-method that overlaps test segments. The second case establishes the lower bound for the length of test sequences generated by any D-method that does not overlap test segments. It is observed that the reduction in the length of test sequences due to overlapping is significant. An efficient algorithm for the generation of test sequences is proposed. This algorithm utilizes a distinguishing sequence and overlaps test segments. Sufficiency conditions are given both for finding a minimum- length test sequence in polynomial time and for constructing the optimal length test sequences by this algorithm 相似文献
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多值“加法型”组合生成器分析 总被引:1,自引:1,他引:0
文中运用信息论原理对多值“加法型”组合生成器序列进行分析,得到钟控序列与输出序列的互信息为零的结论,证明了钟控输入与输出序列之间互信息是输出序列长度的严格递增函数,进而对控选逻辑序列设计进行分析。 相似文献
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Guozhen Zang Cong Ling 《Electronics letters》2001,37(10):631-632
A supplement is provided for Oppermann's orthogonal sequences with a wide range of correlation properties. It is shown that there exist identical sequences within the sequence set under many circumstances. The number of distinct orthogonal sequences in the sequence set is presented 相似文献
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线性复杂度和k- 错线性复杂度是度量密钥流序列密码强度的重要指标。为了更好地研究序列的随机性,该文通过将序列的k-错线性复杂度的计算转化为求Hamming重量最小的错误序列的方法,讨论了序列不同k-错线性复杂度条件下对应的k-错误序列的分布情况。基于Games-Chan算法,该文给出了线性复杂度为2n的2n-周期二元序列的3错误序列的计数公式,计算机编程验证了该文方法的正确性。 相似文献
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《IEEE instrumentation & measurement magazine》2005,8(1):54-59
There are many ways to measure the magnitude of the frequency response of a system. The authors consider three methods and explain why they are not optimal. Then a method that uses pseudorandom sequences and explains why this method is optimal is considered. The authors discuss pseudorandom sequences and show how their properties make them nearly ideal for measuring the magnitude of the frequency response of a system. Several implementations of pseudorandom sequence generators is described. Finally, an example of a measurement made using a pseudorandom sequence is provided. Pseudorandom sequences are used in audio applications to measure the properties of loudspeakers and of rooms. Additionally pseudorandom sequences are made use of in direct sequence spread spectrum. 相似文献
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Coding theorems for individual sequences 总被引:2,自引:0,他引:2
《IEEE transactions on information theory / Professional Technical Group on Information Theory》1978,24(4):405-412
A quantity called the {em finite-state} complexity is assigned to every infinite sequence of elements drawn from a finite sot. This quantity characterizes the largest compression ratio that can be achieved in accurate transmission of the sequence by any finite-state encoder (and decoder). Coding theorems and converses are derived for an individual sequence without any probabilistic characterization, and universal data compression algorithms are introduced that are asymptotically optimal for all sequences over a given alphabet. The finite-state complexity of a sequence plays a role similar to that of entropy in classical information theory (which deals with probabilistic ensembles of sequences rather than an individual sequence). For a probabilistic source, the expectation of the finite state complexity of its sequences is equal to the source's entropy. The finite state complexity is of particular interest when the source statistics are unspecified. 相似文献
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