共查询到19条相似文献,搜索用时 63 毫秒
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提出了一种新的自适应分层多播拥塞控制方案(ALM)。ALM是发送方与接收方共同驱动、由路由器辅助流量控制的拥塞控制方案,通过把发送方的动态分层和接收方的自适应速率调整有机结合,不仅增强了分层多播的适应能力,提高了系统的吞吐量,而且较好地满足了TCP友好性。仿真实验表明,ALM能有效地利用网络带宽,解决网络带宽的异构性问题,并能通过接收端计算TCP友好速率,使接收端达到与TCP流公平竞争网络资源的目的。 相似文献
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针对分层多播接收者的可用带宽异构性问题,提出了一种自适应动态分层多播拥塞控制算法(ADLM).ADLM自适应地运用最优层输率分配算法来满足接收者的异构性,ADLM可以根据网络情况变化动态地调整分层的数量以及每一分层的层速率.仿真实验表明,该拥塞控制策略比分层组播控制常用的典型策略(RLC)更有效地利用网络带宽,解决网络带宽的异构性问题,同时ADLM是TCP友好的,较好地改进了分层多播拥塞控制的性能. 相似文献
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针对分层多播会话与TCP会话共存网络的公平性问题,本文提出了一种新的加权max=min公平准则.定义了分层多播加权max-min公平的概念,给出了具体的分层算法,为分层多播在公平性原则下的有效实施提供了保障. 相似文献
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在许多多播应用中,降低多播树网络费用非常重要.本文提出了加权的基于多播节点的多播路由算法(WDDMC算法).由于改变了DDMC(Destination-Driven routing for low-cost Multicast )算法中的指示函数,适当降低了多播节点作为中间节点的优先级,提高非多播节点作为中间节点的优先级,从而使得多播树更接近最小Steiner树.在随机网络上的仿真结果表明,WDDMC算法的多播树网络费用优于DDMC算法.该算法的复杂度与DDMC算法完全相同. 相似文献
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该文研究了基于网络编码的分层媒体多播中的层速率优化分配问题。通过优化分配层速率,最大化所有接收节点的接收速率总和。由于该问题是一个非线性整数规划的问题,该文提出了一个时间复杂度为O(|V||T|2|E|2)的启发式的层速率分配算法MRAA。算法MRAA根据各接收节点的接收带宽将网络图按分层层数优化分解成子图,每个子图中各接收节点的最大流的最小值即是相应的层速率。模拟实验表明,算法MRAA相比已有算法对网络吞吐量提高15%18%,对各接收节点的平均带宽利用率改善6%10%。 相似文献
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一种基于克隆策略的多播路由算法 总被引:1,自引:0,他引:1
该文针对网络计算中的NPcomplet问题一带时延约束的多播路由问题,提出了一种基于克隆策略的路由算法.仿真实验表明,与基于遗传算法的多播路由算法相比,该算法具有更快的收敛速度和更好的全局寻优能力,而且算法稳定、灵活,操作简单. 相似文献
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This article studies the problem of constructing optimal layered multicast with network coding for heterogeneous networks.Based on the flexibility of layered source coding, a global-favorable optimization scheme is proposed, which maximizes the aggregate throughput of heterogeneous sink nodes for layered multicast with network coding by determining the optimal bit rates of the layers. To solve this global-favorable optimization scheme, especially in the large-scale heterogeneous networks, a new problem-specific genetic algorithm (GA) is further proposed. It not only searches efficiently for the optimal allocation of layer bit rates, but also guarantees the validity of candidate solutions in the whole evolutionary process. Simulation results demonstrate that this new GA-based optimization scheme could obtain efficiently the optimal or satisfactorily near-optimal bit rates for layered multicast with network coding, even in the large-scale heterogeneous networks. 相似文献
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提出了协作多播网络中基于有限反馈的联合子载波和功率分配策略,在满足QoS需求的条件下使功率消耗最小化。该策略首先利用有限的反馈信息在等速率分配下将子载波分给不同的多播组,并提出“公平子载波分配”策略,达到了功率消耗和公平性的折中。然后利用提出的“协作功率迭代”策略完成有效的功率分配,该策略利用注水定理确定每个子载波的目标速率后,又通过一个功率迭代过程实现功率最佳化。仿真结果显示,新的协作策略大大降低了上行反馈开销,且所需功率和多播业务中断概率远远小于直传策略。此外,协作功率迭代策略由于有较低的计算复杂度,因此更适合于实际系统。 相似文献
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Yang Liu Wenbo Wang Mugen Peng Song Zhu 《Wireless Communications and Mobile Computing》2012,12(13):1147-1156
We consider the problem of optimal power allocation and optimal user selection in a layered multicast transmission over quasi‐static Rayleigh fading channels. A scheme based on superposition coding is proposed in which basic multicast streams and enhanced multicast streams are superimposed and transmitted by a base station, while users with worse channel conditions can only decode basic multicast streams, and users with better channel conditions can decode both basic and enhanced multicast streams. In this paper, subject to fixed user selection ratios, the optimal power allocation for each stream that maximizes average throughput is investigated, and the impact of power allocation on average outage probability is discussed. Finally, subject to fixed transmit power and power allocation, the optimal user selection ratio for enhanced multicast streams is also studied. Numerical results show that the optimized layered multicast scheme outperforms the conventional multicast scheme in terms of average throughput. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Markos P. Anastasopoulos Athanasios D. Panagopoulos Panayotis G. Cottis 《International Journal of Satellite Communications and Networking》2009,27(2):117-139
The major problem limiting the scalability of large‐scale multicast satellite networks is feedback implosion that arises whenever a large number of users simultaneously transmit feedback messages (FBMs) through the network, thus occupying a significant portion of satellite system resources. In satellite networks operating above 10 GHz, attenuation due to rain constitutes the dominant fading mechanism deteriorating the quality of service. In this paper, a novel scheme for providing large‐scale reliable multicast services through a star‐based geostationary satellite topology is presented incorporating accurate channel modeling of the propagation phenomena. The new protocol is based on the selection of an area representative that provides quick FBMs aiming at suppressing FBMs originating from the rest of the network users. The scheme provides a timely reaction to changes of either the channel conditions or the network topology by properly updating the selection of representatives. Through appropriate simulations, comparisons and examples it is demonstrated that the new approach suppresses FBMs very effectively. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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基于遗传算法的时延受限代价最小组播路由选择方法 总被引:41,自引:3,他引:38
目前多媒体业务的涌现对网络提出了更高的要求。希望既能满足实时性,又能够高效地利用网络资源。本文提出了一种基于遗传算法的组播路由选择方法,该方法在满足时延限制条件的基础上寻找代价最小的组播树。实验表明,该算法收敛速度快,可靠性高,能够满足多媒体网络对实时性的要求。 相似文献
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基于蚂蚁算法的时延受限分布式多播路由研究 总被引:25,自引:0,他引:25
本文探讨了在高速包交换计算机网络中,具有端到端时延限制的多播路由问题。提出了一种新颖的基于蚂蚁算法的多播路由优化算法,该算法是完全分布式的。仿真实验表明,用该算法产生的多播路由树的费用比已存在的主要算法更好,并且适应于多播成员数的变化。 相似文献
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光网络中基于组播树的静态业务疏导算法 总被引:2,自引:1,他引:1
为了减少波分复用(WDM)网络中波长资源消耗,将组播路由算法的思想运用于静态业务疏导的计算,通过建立业务疏导树来实现静态业务疏导.为了减少疏导树的数量,从而减少网络中波长资源的消耗,将节点间的业务请求分组归并,利用装包算法使业务分组的数量最少,并通过构建最小生成树实现传输路径共享.仿真结果表明,本文的算法可以有效地减少... 相似文献