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针对多径路由带来的端到端测量路径不确定性以及布尔模型不能很好地解决多拥塞链路的问题,该文在识别端到端测量路径的基础上,提出一种基于扩展状态空间的网络拥塞链路识别算法。首先基于探测流时延相关性进行自适应聚类,进而得到各路径与探测流之间的映射关系。其次采用多门限的方式,将具有不同丢包程度的拥塞路径赋予不同的拥塞状态。最后将拥塞链路识别问题转化为一个约束最优化问题,并提出基于扩展状态空间的拥塞链路识别算法(ESSCLI)算法求解该问题。仿真结果表明,ESSCLI算法能够在多种不同网络场景下取得比当前算法更高的拥塞链路检测率。 相似文献
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本论文在分析无线传感器网络不同于普通有线网络的特征后,提出了一种适用于无线传感器网络的TCP 拥塞控制机制DW-TCP,此机制将TCP拥塞窗口分为拥塞丢包窗口和误码丢包窗口,在链路误码率较高时通过降低发送速率提高数据发送的可靠性,节约无线节点的能源消耗和系统不必要的开销,该机制不但考虑到拥塞丢包对数据发送速率的影响,而且考虑到无线链路中的误码丢包对数据发送速率的影响. 相似文献
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无线传感器网络节点通信能力有限,有事件发生时,数据产生速率将急剧增大,网络可能会发生拥塞的问题,提出了一种适合关键信息可靠传输的节点拥塞避免算法CAARTKI (Congestion Avoidance Algorithm for Reliable Transmission of Key Information)。算法主要思想是通过引入区分服务,数据包按其重要性不同划分为不同的优先级,高优先级分组优先得到传输。本算法中,节点只有在下一跳节点为其分配了发送窗口才可以发送数据,以避免节点拥塞发生;在链路层考虑拥塞避免的同时,在路由层通过选择可用缓存空间多的邻居节点作为下一跳节点,使关键信息能及时可靠传输到负载较轻的节点,减少由于负载过重时重要信息不能及时传输的可能;在关键信息密集产生时,采用主动丢包策略,丢弃部分低优先级分组,为高优先级分组腾出缓存区间。NS2仿真实验结果表明:CAARTKI可预防拥塞的产生,最高优先级分组的丢包率低,平均网络时延较小,能保证关键信息的及时可靠传输。 相似文献
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本文提出了一种新的基于速率检测拥塞的ABR流量控制算法--E-EFCI,它的基本思想是在基于速率检测拥塞的基础上扩展EFCI的功能,使其不仅反映网络阻塞状况,而且还反映网络排队状况。在交换机中通过虚拟队列的长度设置EFCI来传递网络的排队信息。仿真结果表明,本文提出的算法比基本EFCI算法具有更好的控制行为,减小了ACR和排队长度的振荡幅度,提高了链路、缓存利用率,加快拥塞解除,并具有较高的性能价格比。 相似文献
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无线网络中TCP友好流媒体传输改进机制 总被引:1,自引:0,他引:1
为保持无线网络中多媒体业务对TCP的友好性,提出了一种适用于无线网络的动态自适应的流媒体传输速率调节机制。该机制通过在接收端区分网络拥塞丢包和链路错误随机丢包,准确判断网络的拥塞状况结合接收端缓存区占用程度,自适应实施多级速率调节,实现了TCP流友好性和流媒体服务质量(QoS)的折中。由于准确区分出无线链路误码丢包和动态调整流媒体QoS要求,该机制能维持较高的网络利用率。仿真实验结果显示在连接数为2和32,链路误码率从0到0.1变化时TCP,TFRC和吞吐量幅度下降幅度较大,WTFCC幅度下降相对较慢,最大相差达2M;在网络负载重时,尽管链路误码率较低,WTFCC区分链路错误与拥塞丢包,因此,端到端丢包率高于TCP和TFRC,但整体传输吞吐量也高于两者。归一化吞吐量显示WTFCC对TCP流友好。 相似文献
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PEI Tingrui LEI Fangqing LI Zhetao ZHU Gengming PENG Xin Youngjune CHOI Hiroo SEKIYA 《电子学报:英文版》2017,26(3)
In wireless sensor networks, congestion leads to buffer overflowing, and increases delay. The tradi-tional solutions use rate adjustment to mitigate congestion, thus increasing the delay. A Delay-aware congestion con-trol protocol (DACC) was presented to mitigate congestion and decrease delay. In order to improve the accuracy of the existing congestion detection model which is based on the buffer occupancy of a single node, DACC presents a new model considering both the real-time buffer occupancy and the average transmission time of packets. DACC uses the untapped bits in the IEEE 802.11 Distributed coordination function (DCF) frames header to carry congestion infor-mation. During the congestion alleviation period, DACC presents a channel occupancy mechanism which is based on the real-time buffer occupancy for the purpose of decreas-ing delay and preventing packet loss. Simulation results indicate that in terms of delay, packet delivery ratio, col-lision and buffer load, DACC has comparative advantages than those of 802.11 DCF, Priority-based congestion con-trol protocol (PCCP) and Decoupling congestion control and fairness (DCCF). 相似文献
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Jui-Chi Chen 《Wireless Personal Communications》2012,67(3):613-630
Base stations in next-generation broadband mobile networks (NGBMNs) must efficiently schedule different kinds of multimedia packets providing different quality of service (QoS) classes. During the past 10?years, many researchers have experimented with various packet scheduling schemes. In this paper we will propose a batch-arrival queuing model for evaluating NGBMN multimedia packet scheduling systems, and for obtaining three performance measures: packet loss rate (PLR), queuing delay (QD), and bandwidth utilization (BU). The three measures can be used to solve utilization optimization problems with QoS constraints. Specifically, a combination of a traffic statistic plus maximum PLR and QD constraints can be used to maximize BU for a multimedia packet scheduling management architecture. According to results from mathematical tests of the proposed model, it offers an efficient approach to managing scheduling buffers. The model and optimized parameters can be applied to flexible bandwidth deployment and classified buffer size control, thus enhancing profitability. 相似文献
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When congestion occurs in a packet queuing system, packets can be dropped from the rear or the front of the queue. It is demonstrated that the probability of a packet being dropped is the same in systems with rear and front packet dropping. It is shown that the probability of a packet being delayed longer than a given value in a system with front dropping is less than or equal to that in a system with rear dropping. It is further illustrated that front dropping not only improves the delay performance on an internodal link, but also provides the overall loss performance for time constrained traffic such as packet voice 相似文献
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文中提出一种基于拥塞程度分级的速率调节算法.首先,对缓冲区进行多尺度排队分析,计算出缓冲区的溢出概率.其次,根据溢出概率的值,把节点拥塞程度分成三级.最后,针对每一级拥塞采取相应的速率调节方案来缓解拥塞.实验结果表明,该算法可以有效缓解拥塞,提高无线传感器网络的数据包投递率. 相似文献
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We consider modeling the statistical behavior of interactive and streaming traffics in high-speed downlink packet access (HSDPA) networks. Two important applications in these traffic categories are web-browsing (interactive service) and video streaming (streaming service). Web-browsing is characterized by its important sensitivity to delay. Video streaming on the other hand is less sensitive to delay, however, due to its large frame sizes, video traffic is more affected by the packet loss resulting from a limited buffer size at the base station. Taking these characteristics into account, we consider modeling the queuing delay probability density function (PDF) of the Web-browsing traffic, and modeling the queuing buffer size distribution of video streaming traffic. Specifically, we show that the queuing delay of the Web-browsing traffic follows an exponential distribution and that the queuing buffer size of video streaming traffic follows a weighted Weibull distribution. Model fitting based on simulated data is used to provide simple mathematical formulations for the different parameters that characterize the PDFs under consideration. The provided equations could be used, directly, in HSDPA network dimensioning and, as a reference, to satisfy a certain quality of service (QoS). 相似文献
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Congestion control for multimedia services 总被引:1,自引:0,他引:1
The problem of congestion control in high-speed networks for multimedia traffic, such as voice and video, is considered. It is shown that the performance requirements of high-speed networks involve delay, delay-jitter, and packet loss. A framing congestion control strategy based on a packet admission policy at the edges of the network and on a service discipline called stop-and-go queuing at the switching nodes is described. This strategy provides bounded end-to-end delay and a small and controllable delay-jitter. The strategy is applicable to packet switching networks in general, including fixed cell length asynchronous transfer mode (ATM), as well as networks with variable-size packets 相似文献
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Congestion control in wireless sensor networks (WSNs) is crucial. In this article, we discuss congestion control and the adaptive load-aware problem for sensor nodes in WSNs. When the traffic load of a specific node exceeds its the available capacity of the node, a congestion problem occurs because of buffer memory overflow. Congestion may cause serious problems such as packet loss, the consumption of power, and low network throughput for sensor nodes. To address these problems, we propose a distributed congestion control protocol called adaptive load-aware congestion control protocol (ALACCP). The protocol can adaptively allocate the appropriate forwarding rate for jammed sensor nodes to mitigate the congestion load. Through the buffer management mechanism, the congestion index of neighboring sensor nodes, and an adjustment of the adaptive forwarding rate, the degree of congestion is alleviated markedly. The performance in allocating the forwarding rate effectively to neighboring sensor nodes also improves. The ALACCP can avoid packet loss because of traffic congestion, reduce the power consumption of nodes, and improve the network throughput. Simulation results revealed that the proposed ALACCP can effectively improve network performance and maintain the fairness of networks. 相似文献