共查询到20条相似文献,搜索用时 62 毫秒
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互连网络为数据、音频和视频等应用提供不同的实现服务质量(QoS)的策略,如集成服务模型IntServ、差分服务模型DiffServ和多标签交换协议MPLS等。随着多播应用的出现,上述技术不能有效地为多播提供端到端的服务质量。分析上面各种技术在多播应用中的不足,并给出了不同文献提出的解决方案,同时也分析了异构网络实现满足服务质量的多播策略和遇到的问题。最后指出了实现多播服务质量要解决的问题。 相似文献
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讨论了DVB-RCS标准的安全规范,并针对现有规范在多播安全性上的缺陷,提出了改进方案.通过扩展MKE,QKE和EKE消息发送密钥改进发送与更新多播密钥方案,达到了提供安全的多播卫星服务的目的. 相似文献
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本文结合距离向量多播路由技术(DVMRP)多播路由技术介绍了移动IP下的多播技术,指出其存在的问题,并给出了一个解决方案。 相似文献
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无线Mesh网络多播路由是无线路由必须解决的关键技术。部分研究者对网络资源和服务质量(QoS)进行研究,提出了建立最短路径树、最小开销树、负载感知、信道分配多播等多播算法;有的算法考虑链路可靠性,建立备用路径。将结合网络资源和可靠性对多播路由算法进行研究,提出了建立可靠多播树(RT,Reliable Tree)的多播路由算法:可靠多播树是一个多树结构,由一棵首选多播树和一棵多径树构成,多径树提供可靠多路径,以提高网络吞吐量。 相似文献
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本文提出了k元n立方的m子立方体连通图的定义,讨论了该图的连通性。利用k元n立方的m子立方体连通图的概念提出了可容纳大量错误结点的容错路由算法,并对算法的时间复杂度做了分析。 相似文献
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多播网络中基于网络编码的高效丢失恢复机制 总被引:2,自引:0,他引:2
网络编码为无线网络中可靠多播通信提供了有效解决途径。该文分析了网络中编码机会的变化规律,研究了解码失败的编码数据包对网络编码性能的影响,提出了新的基于网络编码的丢失恢复算法(NCLR)。NCLR要求节点缓存解码失败的编码数据包,并反馈信息给发送节点。根据各个节点的丢包情况,NCLR通过优先传输对编码性能影响较大的数据包,并在需要重传的已编码数据包和原始数据包中选择编码组合,来充分挖掘网络中的编码机会。仿真结果表明相对于已有算法,NCLR算法可以在重传次数和丢失恢复时延方面有显著性能改善。 相似文献
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Antonios Alexiou Dimitrios Antonellis Christos Bouras 《Wireless Personal Communications》2008,44(4):455-471
In this paper, we present an efficient scheme for the multicast transmission of the data in the Universal Mobile Telecommunications
System (UMTS). We take advantage of the tree topology of the examined network and we introduce the use of Routing Lists (RLs)
in the nodes of the UMTS. The adoption of these lists leads to the decrement of the transmitted packets and to the efficient
use of network resources in the multicast transmission of the data. We describe in detail the appropriate steps for the successful
multicast transfer of data. Furthermore, we analyze the handling of special cases such as user mobility scenarios. Especially,
the various handover types are examined along with the Serving Radio Network Subsystem relocation procedure. Finally, we implement
our approach in the NS-2 simulator and we present the performance of the multicast mechanism. 相似文献
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安全组播通信使用组内所有成员共享的组密钥来加密通信内容。为了保障安全,密钥服务器需要在组成员关系改变时进行组密钥更新(rekey)。由于组内成员关系的动态性和加解密操作的高代价,组密钥更新性能成为衡量组密钥管理性能的主要指标。基于密钥树(key tree)的组密钥更新方法已经被广泛地使用,并达到了对数级的组密钥更新代价。密钥树的结构需要保证平衡,否则最坏情况下组密钥更新的通信代价会达到O(n)。该文提出了一种新的基于密钥树的路径洗牌算法PSA(Path Shuffling Algorithm),该算法能够将密钥树的平衡操作分散到一般的更新密钥操作中,减少了结构调整代价,从而提高了算法的性能。理论分析给出了该算法更新组密钥的平均通信代价,模拟实验也验证了这种算法更新组密钥的平均性能要优于其它同类算法。 相似文献
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IP 组播技术是一种可以把单个数据信息同时分发到不同的用户去的网络技术。卫星网络固有的广播信道特性使得它很适合组播应用。然而目前针对卫星网络的可靠组播服务研究很少,虽然已经有一些关于地面Internet组播协议建议,但他们并不适合于卫星网络。在卫星网络组播传输中的一个关键技术是传输协议设计。该文提出一种基于Agent的宽带卫星网络可靠组播传输协议(ASMTP)。该协议利用接收端Agent来实现卫星组播,采用分组级FEC和本地差错恢复纠正传播中的非相关错误和相关错误。在ASMTP中,还实现了流量控制和拥塞控制机制。仿真结果表明,在卫星网络环境中,ASMTP性能优于MFTP(Multicast File Transport Protocol),同时具有较好的网络可扩展性。 相似文献
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基于一次签名的认证应用很广,通常的方法有在线,离线签名和前向安全的签名,但组播环境下的高效签名方案极为少见。这里提出了一种一次签名方案,它是一种对于签名生成和签名验证都极为高效的方案,而且签名长度很短。特别适用于组播通信的数据源认证。 相似文献
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In this paper a methodology for adapting existing wireless ad hoc network protocols to power controlled networks is presented. Wireless nodes are assumed to have transmission power control with m discrete levels, and a clustering scheme is used in the adaptation to be energy efficient. Clusters are formed among the nodes in a distributed self-organized manner so that each node is a member of some cluster and within a cluster, each node can reach any other node with an appropriate power level. Each cluster has a designated head node which acts as forwarding agent for its members and these head nodes form a supernode topology. We adapt an ad hoc network multicast protocol by executing it on this supernode topology. Multicast data will move from the sender to its cluster head, then along the supernode topology according to the results of the chosen multicast protocol, and finally from the cluster head to receivers within their clusters. At every step, nodes use an appropriate power level j, 1jm, to reach all the intended recipients. For more balanced way of depleting energy in the network, nodes take turn to become cluster heads. We applied our technique to ODMRP and the experiment shows significant energy reduction. 相似文献
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Ki-Il Kim 《Wireless Personal Communications》2007,43(4):1633-1651
Performance of multicast routing protocol in mobile ad hoc networks is mostly characterized by underlying forwarding structure.
Currently, general structures based on tree/mesh based scheme cannot handle with transmission efficiency, robustness to dynamic
topology, scalability, and load balancing functionalities at the same time. To handle above key performance factors concurrently,
we propose a new virtual backbone architecture for multicast, which is based on hierarchical hypercube structure. Due to the
natural properties of hypercube structure, we can achieve efficiency, robustness and load balance in mobile ad hoc networks
where links are frequently broken owing to nodes’ free immigration. Furthermore, scalability problem is naturally resolved
by hierarchical structure. Finally, through simulation results, we have proven good scalability by demonstrating that our
structure can provide higher packet delivery ratio with low control overhead and better scalability than tree/mesh based scheme
without regard to the number of group members. 相似文献
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An Efficient Multicast Routing Protocol in Wireless Mobile Networks 总被引:11,自引:0,他引:11
Providing multicast service to mobile hosts in wireless mobile networking environments is difficult due to frequent changes of mobile host location and group membership. If a conventional multicast routing protocol is used in wireless mobile networks, several problems may be experienced since existing multicast routing protocols assume static hosts when they construct the multicast delivery tree. To overcome the problems, several multicast routing protocols for mobile hosts have been proposed. Although the protocols solve several problems inherent in multicast routing proposals for static hosts, they still have problems such as non-optimal delivery path, datagram duplication, overheads resulting from frequent reconstruction of a multicast tree, etc. In this paper, we summarize these problems of multicast routing protocols and propose an efficient multicast routing protocol based on IEFT mobile IP in wireless mobile networks. The proposed protocol introduces a multicast agent, where a mobile host receives a tunneled multicast datagram from a multicast agent located in a network close to it or directly from the multicast router in the current network. While receiving a tunneled multicast datagram from a remote multicast agent, the local multicast agent may start multicast join process, which makes the multicast delivery route optimal. The proposed protocol reduces data delivery path length and decreases the amount of duplicate copies of multicast datagrams. We examined and compared the performance of the proposed protocol and existing protocols by simulation under various environments and we got an improved performance over the existing proposals. 相似文献
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组播通信正成为不断增长的应用基础,而其关键是要为组通信提供可靠的安全机制,然而,现有的组播安全协议仅能提供部分的解决方法,考虑到源认证是组的最主要安全事务之一,文章基于消息认证码提出了一种安全有效的组播源认证方法。 相似文献