A rate-based flow control mechanism for avoiding congestion

The rate-based flow control mechanisms for the Available Bit Rate(ABR)service are used to share the available badwidth of a bottleneck switch connected to a bottleneck link fairly and reasonably among many competitive users,and to maintain the buffer queue length of the witch at a desired level in order to avoid congestion in Asynchronous Transfer Mode(ATM)networks.In this Paper,a control theoretic approach that uses a Deadbeat-Response(DR) controller to the desing of a rate-based flow control mechanism is presented.The mehanism has a simple structure and is robust in the sense that its stability is not sensitive to the change of the number of active Virtual Connections(VCs),Simulation results show that this mechanism not only ensures fair share of the bandwidth for all active VCs regardless of the nmuber of hops they traverse but also has the advantages of fast convergence ,no oscillation,and high link bandwidth utilization.     

A modified flow enforcement technique for ATM networks

In ATM networks the requirement of providing the negotiated Quality of Service (QOS) needs an efficient flow enforcement technique that will result in preventive congestion control. A very effective technique is the Exponentially Weighted Moving Average (EWMA) method. In this paper, we have suggested improvements to the EWMA and call it the Enhanced EWMA (EEWMA). Simulation results show that the EEWMA is consistently better than the EWMA in most of the situations. We present comparisons of cell loss under various conditions. No theoretical analysis is presented.     

无线传感器网络中逐级递推的流量控制机制

随着传感器网络负荷的增加,拥塞将会导致网络性能的大幅下降。采用基于反馈的无线传感器网络流量控制机制,通过对拥塞节点的前一跳节点进行流量控制,来实现控制流入拥塞节点的流量大小,平衡经过拥塞节点流量的流入和流出速率,在很大程度上改善了网络性能,提高了网络服务质量。     

Fuzzy neural network based traffic prediction and congestion control in high-speed networks

Congestion control is one of the key problems in high-speed networks,such as ATM.In this paper,a kind of traffic prediction and preventive congestion control scheme is proposed using neural network approach.Traditional predictor using BP neural network has suffered from long convergence time and dissatisfying error.Fuzzy neural network developed in this paper can solve these problems satisfactorily.Simulations show the comparison among no-feedback control scheme,reactive control scheme and neural network based control scheme.     

多通道ATM 网络鲁棒拥塞控制

拥塞控制对ATM网络有效、稳定运行具有重要的作用，在单瓶颈多通道的网络模型下，基于Smith预估原理，提出一种新颖的鲁棒拥塞控制器设计方案，这种基于速率的拥塞控制可以保证ABR的服务质量(QoS)，理论分析和仿真结果表明，所提出方案收敛速度快，对网络的不确定因素具有较强的鲁棒性。     

基于Additive2multipl icative 模糊 神经网的ATM 网络拥塞控制

考虑了模糊神经网络的学习功能，提出利用Additive-multiplicative模糊神经网络(AMFNN)对ATM网络进行拥塞控制的方案．在拥塞控制过程中，利用AMFNN模糊神经网络预测下一个将要到达流的特征，结合当前缓冲区的队列信息预测网络是否发生拥塞．一旦预测出将有拥塞发生，控制器则向源端反馈拥塞控制信息，信源根据拥塞信息适当降低传输速率，从而避免了拥塞的发生．仿真结果表明，该方法可改善网络对拥塞的实时处理能力，提高网络资源的利用率．     

PSTCP：小缓存高速网络拥塞控制算法

针对当前网络拥塞控制算法在极小缓存高速网络中带宽利用率差的问题,研究了TCP机制本身造成的突发流量现象,提出一种新的拥塞控制算法——PSTCP。在整个网络连接过程中,该算法采用“隔开”平滑发送的思想;在网络拥塞发生时,采用公平因子c和减少因子decrement对窗口进行实时微调。实验表明,PSTCP在小缓存区、高带宽网络环境下,保障了高的带宽利用率,有好的收敛性和公平性。     

Analysis of MIMD congestion control algorithm for high speed networks

Proposals to improve the performance of TCP in high speed networks have been recently put forward. Examples of such proposals include High Speed TCP, Scalable TCP, and FAST. In contrast to the additive increase multiplicative decrease algorithm used in the standard TCP, Scalable TCP uses a multiplicative increase multiplicative decrease (MIMD) algorithm for the window size evolution. In this paper, we present a mathematical analysis of the MIMD congestion control algorithm in the presence of random losses. Random losses are typical to wireless networks but can also be used to model losses in wireline networks with a high bandwidth-delay product. Our approach is based on showing that the logarithm of the window size evolution has the same behaviour as the workload process in a standard G/G/1 queue. The Laplace–Stieltjes transform of the equivalent queue is then shown to directly provide the throughput of the congestion control algorithm and the higher moments of the window size. Using ns-2 simulations, we validate our findings using Scalable TCP.     

ATM 网络预测拥塞控制器设计

网络传输中存在严重的不确定性，由此限制了常规反馈拥塞控制算法的应用．利用预测控制方法，设计出一种改进的拥塞控制算法，增强了闭环系统的鲁棒性和稳定性，实现了带宽分配的公平性．仿真结果证实了所提出方法是有效性的。     

XCP与TCP的拥塞控制算法比较分析

互联网用户数量激增,使得网络的拥塞问题变得越来越严重,拥塞控制是确保Internet鲁棒性的关键因素,因此拥塞控制问题成为目前关于Internet研究的难点问题.分析了传统的TCP拥塞控制算法存在一些不足,并对比分析了一种新的XCP拥塞控制算法.试验结果表明,XCP协议算法具有链路利用效率高、公平性好、可扩展性强、排队时延小的优点,并且路由器的开销也非常小.     

ATM网络ABR业务的公平流量控制的研究

ATM网中ABR业务能根据网络信道情况动态地调整速率。本文讨论了针对ABR业务的几种流量控制机制,对它们各自的特点作了比较深入的分析和研究,提出了作者自己的改进方法,使网络的性能得到了改善。     

基于最优化流控模型的拥塞控制算法

在已改进的最优化流控模型和链路价格算法的基础上,提出了一种基于最优化流控模型的拥塞控制算法。NS-2模拟实验结果证明,与类似的显式精确反馈拥塞控制算法XCP相比,新算法有更好的稳定性和相同的带宽利用率。     

Binary ABR flow control over ATM networks with uncertainty using discrete-time variable structure controller

A binary available bit rate (ABR) scheme based on discrete-time variable structure control (DVSC) theory is proposed to solve the problem of asynchronous transfer mode (ATM) networks congestion in this paper. A discretetime system model with uncertainty is introduced to depict the time-varying ATM networks. Based on the system model, an asymptotically stable sliding surface is designed by linear matrix inequality (LMI). In addition, a novel discrete-time reaching law that can obviously reduce chatter is also put forward. The proposed discrete-time variable structure controller can effectively constrain the oscillation of allowed cell rate (ACR) and the queue length in a router. Moreover, the controller is self-adaptive against the uncertainty in the system. Simulations are done in different scenarios. The results demonstrate that the controller has better stability and robustness than the traditional binary flow controller, so it is good for adequately exerting the simplicity of binary flow control mechanisms.     

Congestion control in high-speed communication networks using the Smith principle

High-speed communication networks are characterized by large bandwidth-delay products. This may have an adverse impact on the stability of closed-loop congestion control algorithms. In this paper, classical control theory and Smith’s principle are proposed as key tools for designing an effective and simple congestion control law for high-speed data networks. Mathematical analysis shows that the proposed control law guarantees stability of network queues and full utilization of network links in a general network topology and traffic scenario during both transient and steady-state condition. In particular, no data loss is guaranteed using buffers with any capacity, whereas full utilization of links is ensured using buffers with capacity at least equal to the bandwidth-delay product. The control law is transformed to a discrete-time form and is applied to ATM networks. Moreover a comparison with the ERICA algorithm is carried out. Finally, the control law is transformed to a window form and is applied to Internet. The resulting control law surprisingly reveals that today's Transmission Control Protocol/Internet Protocol implements a Smith predictor for congestion control. This provides a theoretical insight into the congestion control mechanism of TCP/IP along with a method to modify and improve this mechanism in a way that is backward compatible.     

无线传感器网络拥塞控制研究*

介绍了无线传感器网络拥塞控制的内容和特点,仔细分析了在无线传感器网络中实施拥塞控制算法所涉及的技术难点及不足,并对现有工作进行了归纳和总结.最后,探讨了发展初期该研究领域的未来发展方向.     

一种无线传感器网络的优化速率控制方法

拥塞控制是无线传感器网络中的一个关键性问题。从解决拥塞问题出发,提出了一个基于优化速率的拥塞控制算法ORCC。算法构建了一个分布式的分簇网络结构,利用缓冲的占用情况进行拥塞检测,并使用基于优化理论的速率调节策略来保证网络吞吐量的稳定,从而通过求解出的最优解来实现簇内节点效用的最大化。仿真实验表明,ORCC算法不仅能有效缓解网络拥塞,降低平均延迟,还具有较好的网络传输公平性。     

Routing with admission control in ATM networks

An optimal control parameter, , was developed by optimal control theory for Asynchronous Transfer Mode (ATM) networks. The parameter is related to link utilization, buffer occupancy, system throughput and cell rejection characteristics and is applied to routing and admission control in simulation of a network carrying multiclass traffic. Simulation results show that the parameter produces better performance with respect to cell rejection rate characteristics compared with the traditional control parameter for utilization, .This research has been supported by the ATI as part of the Navy Contract N00140-94-C-BC03. Some parts of the paper were presented at Globecom'94.     

无线自组网络QoS流的准入控制和流量控制

作者曾提出一个QoS路由和准入控制机制－QDSR,并且在小规模实时视频传输实验床上实现了这些方案。虽然QDSR的准入控制只保证每个节点有足够的可用带宽给准入的所有流使用,但并不保证每个流在较小的时间尺度上得到请求的带宽。为此,作者对QDSR的准入控制机制进行了改进并增加了流量控制机制,以满足实时应用的QoS需求。在NS2仿真环境中实现了QDSR以及对QDSR的改进。仿真结果表明,改进机制改善了QDSR的视频流的传输质量,较好地提高了视频流的吞吐率和投递率,减小了数据包的端到端延迟,并且能很好地满足包括视频传输在内的多种业务的传输需要。     

Binary ABR flow control over ATM networks with uncertainty using discrete-time variable structure controller

A binary available bit rate （ABR） scheme based on discrete-time variable structure control （DVSC） theory is proposed to solve the problem of asynchronous transfer mode （ATM） networks congestion in this paper. A discrete-time system model with uncertainty is introduced to depict the time-varying ATM networks. Based on the system model, an asymptotically stable sliding surface is designed by linear matrix inequality （LMI）. In addition, a novel discrete-time reaching law that can obviously reduce chatter is also put forward. The proposed discrete-time variable structure controller can effectively constrain the oscillation of allowed cell rate （ACR） and the queue length in a router. Moreover, the controller is self-adaptive against the uncertainty in the system. Simulations are done in different scenarios. The results demonstrate that the controller has better stability and robustness than the traditional binary flow controller, so it is good for adequately exerting the simplicity of binary flow control mechanisms.     

主动网络拥塞控制研究与实现

随着Internet的迅速发展,网络流量急剧增长,网络的拥塞问题日益突出,阐述了拥塞产生的原因,介绍了主动网络的思想和体系结构,着重探讨了主动网络在拥塞控制和网络管理等方面的应用,描述了主动拥塞控制系统中主动节点的内部结构,提出了主动拥塞控制系统的一种实现.实验结果显示,实行主动拥塞控制的网络比实行传统拥塞控制的网络在性能上有了一定程度的提高.