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研究了基于WLAN访问Internet的网络基站处流,提出了一种基于队列长度的调度方法和基于信道容量的拥塞控制模式,以达到网络资源的公平分配,并解决由于不恰当处理基站处堆积数据包而引起的弊端。在提出的资源分配模型中,调度算法根据各条流堆积的队列长度来随机地选择将要发送的数据分组;而拥塞控制模式中,将链路使用率作为拥塞指示,通过计算,平等地反馈给每一条流的发送端。发送端根据反馈到的拥塞信息来调整发送速率,以达到资源分配的公平性。仿真的结果表明:各条流能公平地共享无线网络的带宽。此算法的最大的优点在于基站不需要按照某种特定的公平性定义来选择数据包却能达到很高的公平性。 相似文献
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随着新型业务类型如视频会议、网络游戏、交互应用等不断涌现,如何利用有限的网络资源进行有效的流量控制,以保障业务的服务质量(Quality of Service,QoS)已成为一个非常迫切的问题。而目前已有的QoS流量控制方法大多存在着对网络资源的利用率低、可靠性差、粒度粗、实现困难,可扩展性差等问题。软件定义网络(Software Defined Network,SDN)提出的控制层与数据层分离思想,为解决此类问题提供了崭新的思路。本文提出了一种基于OpenFlow技术的QoS流量控制方法,利用自适应多约束QoS路由技术,提高了QoS控制的灵活性与可靠性,实现了对网络资源的高效利用和业务流控制的细粒度。最后,我们在OpenvSwitch环境下验证了该方法的有效性。 相似文献
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接纳控制技术作为一种有效的、预防性的流量控制手段,是避免网络拥塞、实现网络QoS保障的重要技术。MPLS是ITU-T和IETF共同推出的支持QoS的宽带技术,因此研究基于M PLS的接纳控制技术有着十分重要的意义。本文总结了接纳控制技术的研究现状,提出了各种接纳控制技术在MPLS网络中的应用及其实现方式,并预测了MPLS接纳控制技术未来研究和发展的主要方向和热点问题。 相似文献
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无线传感器网络的拥塞控制技术 总被引:18,自引:0,他引:18
无线传感器网络的多对一通信方式、无线链路的相互干扰、网络的动态变化和资源受限等特性,使得无线传感器网络容易出现拥塞,严重影响网络的QoS传输性能和生存周期,因此拥塞控制成为无线传感器网络服务质量保障机制的关键技术之一.在分析无线传感器网络特点的基础上,说明了拥塞检测和拥塞避免的策略,重点介绍和分析了基于速率控制、流量调度和传输调度等典型的拥塞解除算法,最后对拥塞控制技术的发展趋势进行了展望. 相似文献
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针对IEEE 802.16j网络,提出了一种上行业务的动态联合带宽资源调度方案。根据该网络系统树状拓扑结构,在基站BS和中继站RS间采用分级分布式资源调度体制,从而既保障了业务的带宽需求,又提升了上行带宽利用率,同时还提出了针对不同类型业务采用不同的调度算法,改善了调度的公平合理性。仿真结果表明,提出的动态联合调度方案相比严格优先级调度更具灵活性,能够在兼顾用户速率公平的条件下有效地保证各种服务的QoS要求,同时也可获得较高的带宽资源利用率。 相似文献
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为保证网络流媒体传输质量,在流媒体的传输中需要采用有效的拥塞控制策略.结合流媒体数据对时延敏感的特点,提出了一种基于累积时延的模糊拥塞控制算法,该算法在流媒体数据流传输过程中检测和跟踪其时延,在转发分组数据前,根据容忍时延阈值,丢弃超时数据包,减少不必要的带宽浪费,并且对所到达的数据流按照累积时延进行优先级分类,把全局性缓冲区和各队列的局部性缓冲区按照正常、拥塞避免和拥塞的规则划分为3个具有交叉过渡域的阶段,然后采用整体和局部相结合的拥塞控制方法,实现队列调度过程中的模糊处理,从而对网络拥塞进行有效的控制.理论分析和实验结果表明,使用基于累积时延的模糊拥塞控制算法,能有效改善流媒体的传输性能,是解决流媒体传输拥塞控制的有效途径,并能对提高网络性能起到重要作用. 相似文献
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数据中心(data center, DC)之间通过部署流量工程来提高连接各个数据中心骨干网的利用率,虽然效率提升显著,但对不同类型汇聚流的带宽分配的公平性没有考虑.将多个汇聚流对带宽分配的竞争行为建模为一个合作博弈,通过寻求此博弈的纳什谈判解(Nash bargaining solution, NBS)来确定优化的带宽分配策略CGBA(cooperation game based bandwidth allocation),权衡各汇聚流的最小带宽保证与带宽分配的公平性.在Mininet平台上进行实验仿真并和典型的带宽分配策略对比,结果表明CGBA不但可保证各汇聚流的最小带宽需求,还确保了各类流对带宽资源竞争的公平性. 相似文献
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With the increasing complexity of distributed real‐time systems, the need for improved CAN bus performance is continually increasing. Normally, a scheduling scheme with static‐priority has low network schedulability/utilization; while using dynamic priority will improve the QoS of the network at the cost of a narrow service range or a high overhead, compared with the fixed priority scheduling schemes. Actually, because of the fluctuation of network traffic, these priority policies may not guarantee flexibility for different kinds of messages. Based on the broadcast nature of the CAN bus, a closed‐loop fuzzy scheduling scheme is proposed in this paper. Compared with the dynamic priority schemes, this fuzzy scheduling scheme uses fewer bits to encode fewer priority levels, which widens the service range of the network without increasing overhead. Based on game theory, a fuzzy parameter updating algorithm for the fuzzy scheme is developed to improve the adaptation of the scheme, which guarantees the required QoS of the network even with traffic fluctuation. Simulation results well demonstrate the abilities of the fuzzy scheme to guarantee high schedulability for real‐time messages, as well as the fairness and the same QoS for non‐real‐time messages in networks. 相似文献
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MPLS网络中基于约束路由机制实现流量工程的研究 总被引:3,自引:1,他引:3
传统内部网关协议(IGP)容易造成网络资源使用的不均衡,引起网络拥塞,导致网络性能下降,服务质量无法保证。流量工程是解决这一问题的有力工具,它可以为网络用户提供各种QoS保证,同时提高网络性能、优化网络资源的使用。多协议标签交换(MPLS)为流量工程的实施提供了便利,其核心技术就是基于约束的路由机制。论文对基于约束的路由机制进行了重点论述,为其建立了数学规划模型,并给出了常用的优化算法。 相似文献
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Hyun-Woo KimJun-Hui Lee Yong-Hoon Choi Young-Uk ChungHyukjoon Lee 《Computer Communications》2011,34(1):99-106
With fast proliferation of QoS-enabled wireless packet networks, need for effective QoS control is increasing. In this paper, we focus on QoS provisioning in Mobile WiMAX access service network (ASN). We investigate a dynamic bandwidth provisioning method that can help to increase resource utilization. Our approach consists of two stages: traffic forecasting, followed by bandwidth provisioning. For the first stage, we use auto-regressive integrated moving average (ARIMA) model to forecast traffic based on online measurement. For the second stage, we use a bandwidth provisioning scheme that allocates bandwidths depending on the traffic forecasting. We modeled our problem as a Fractional Knapsack Problem for which we used a greedy algorithm in order to find an approximate solution. Through simulation studies with real-world data sets, we found that our approach could increase the bandwidth for the real-time traffic class and guarantee adequate service quality for the nonreal-time traffic class as well, while maximizing resource utilization. 相似文献
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为了在WLAN标准IEEE 802.11e中高效、高质量地传输各类业务,以及保证业务之间的公平性,提出一种基于自适应信道预留的接纳控制算法。算法中首先采用资源共享的方法提前为业务预留适当的信道资源,使用信道利用率作为接入准则,当网络资源不足时采用自适应地调节已经接入业务流的服务质量来满足新请求的业务流的服务质量需求。结果表明,该算法保证了各业务之间的公平性以及服务质量需求,而且最大程度地接入了更多的业务流,提高了网络的整体性能。 相似文献
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Most of QoS-capable IEEE 802.11 MAC protocols are unable to deliver sustained quality of service while maintaining high network utilization, particularly under congested network conditions. The problem often resides in the fact that flows belonging to the same service class are assigned the same MAC parameters regardless theirs respective bitrate, which leads to throughput fairness rather than perceived QoS fairness. Harmonizing MAC parameters of traffic classes's flows may further lead to sub-optimal situations since certain network configurations (in terms of per class traffic load) can not be accommodated without reassigning the basic MAC parameters. In this paper, we propose a new cross-layer MAC design featuring a delay-sensitive backoff range adaptation along with a distributed flow admission control. By monitoring both MAC queue dynamics and network conditions, each traffic class reacts based on the degree to which application QoS metrics (delay) are satisfied. Besides, we use a distributed admission control mechanism to accept new flows while protecting the active one. Simulation results show that compared to the enhanced distributed coordination function (EDCA) scheme of 802.11e, our protocol consistently excels, in terms of network utilization, bounded delays, and service-level fairness. 相似文献
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适用于实时应用的网络服务自适应系统 总被引:1,自引:0,他引:1
随着网络带宽可用性的提高以及网络延迟的减少,如何在端主机上保证网络传输的服务质量(End-hostQoS)已经逐渐成为一个关键的问题。尤其是针对分布式实时应用的环境:媒体流服务器,视频会议以及VoIP((Voiceover Internet Protocol)是一种以IP电话为主,并推出相应的增值业务的技术应用)。End-hostQoS的实现需要操作系统的支持,比如提供网络层的系统调度和流量控制。笔者在这篇文章中提出的QoS自适应系统可以在最优使用系统资源的基础上提供per-flow或者per-service-class的差别服务。并且通过将EDF调度算法同PID控制理论相结合,保证系统的实时响应、适应网络波动,在服务器瞬间过载的情况下,保证网络服务质量的平稳过渡。 相似文献
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This paper shows that throughput parameter “bits/s” does not provide accurate insight in load conditions and/or traffic demands in Wireless LANs (WLANs). A multi-service traffic profile that does provide this insight is therefore defined. The multi-service traffic profile is natural to define network resource demands for real-time applications. Simulation results are used to show how to set the traffic profile parameters for elastic traffic. The paper subsequently uses the multi-service profiles to define the notion of a QoS budget. The QoS budget is given to a terminal and the terminal can determine locally if network consumption does not exceed the budget and whether a new network greedy application fits within the QoS budget given. Finally, it is shown how the QoS budget with its multi-service traffic profiles can be used to guarantee quality of service in wireless LANs, in a situation where WLAN channel conditions may vary in time and WLAN stations may move around within a BSS. Simulation results found in literature are used to validate the accuracy of the novel algorithms proposed to guarantee QoS in wireless LANs. 相似文献
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为了减少P2P流量对网络带宽造成的影响,合理分配和利用网络资源,更好地保障网络QoS,准确检测和控制P2P流量,提出一种基于Linux系统的P2P流量检测和控制的解决方案,通过扩展Netfilter/Iptables 框架,根据特征码识别P2P连接,和Linux QoS工具一起使用以限制P2P的带宽占用,避免了P2P等... 相似文献