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1.
A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate for all traffic sources as controller output signals is tuned in a body, the proposed method adjusts the coding rate for only a part of the traffic sources while the remainder sources send the cells in the previous coding rate in case of occurrence of congestion. The controller output signals include the source coding rate and the percentage of the sources that send cells at the corresponding coding rate. The control methods not only minimize the cell loss rate but also guarantee the quality of information (such as voice sources) fed into the multiplexer buffer. Simulations with 150 ADPCM voice sources fed into the multiplexer buffer showed that the proposed methods have advantage over the previous methods in the aspect of the performance indices such as cell loss rate (CLR) and voice quality. 相似文献
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INTRODUCTION The development of network technology led to the appearance of many high-speed networks with bandwidth larger than 1 Gbps, or even 10 Gbps. Through high-speed networks, applications like sci- entific collaboration, telemedicine, and real-time environment monitoring can transfer high-bandwidth real time data, images, and video captured from re- mote sensors such as satellite, radars, and echocar- diography. What is more, data intensive grid applica- tion (Foster et al., 2001)… 相似文献
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徐阳 《温州职业技术学院学报》2012,12(1):56-59
大部份TCP拥塞控制机制是依赖分组丢失来触发的,容易产生拥塞。为减少拥塞的产生,提出TCPMlc拥塞控制机制,即借助路由器辅助把网络内部信息传递给发送端,不需要依赖分组丢失,在发生拥塞前就可进行适度的传输控制,以减少因分组丢失而造成传输速度的剧烈下降,并可快速达到最佳传输速度。实验表明,该方法能有效避免拥塞的产生,降低丢包率,提高整体吞吐量。 相似文献
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INTRODUCTION Communication networks are growing quickly. Throughput, delays and losses become unpredictable because of heterogeneity and congestion. This results in lack of quality of service. Today’s solution is based on standard video codecs (as MPEG-2) that do not allow scalability and yield low quality at low bit-rates, complex forward error correction (FEC) codes that are not easily used with time-varying channels and must be set to face the worst case, and automatic repeat re- q… 相似文献
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城市道路间断交通流综合拥挤指标分析(英文) 总被引：1，自引：0，他引：1
为了研究城市道路间断交通流的交通拥堵特性,提出了一种综合评价方法.首先,采用相关分析的方法研究了调查所得的间断交通流参数之间的关系,并将交通流参数分为基础参数和运行参数2类,进而采用多项式回归的方法拟合了运行参数与基础参数的非线性关系.然后,提出了一个综合考虑运行特性和流量特性的综合拥挤模型,该模型以基础参数为输入,0~1之间的无量纲拥挤度值为输出.最后,通过实例分析,对提出的综合评价方法和现有拥挤评价方法进行了对比.结果表明,相比现有评价方法,所提出的评价指标能够同时表征运行参数和基础参数的变化对交通拥挤的影响,能够更加均衡地评价交通拥堵. 相似文献
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Asymmetric stereoscopic video coding can take advantage of binocular suppression in human vision by representing one of the two views in lower quality.This paper proposes a bit allocation strategy for asymmetric stereoscopic video coding.In order to improve the accuracy of bit allocation and rate control in the left view,a proportionalintegral-derivative controller is adopted.Meanwhile,to control the quality fluctuation between consecutive frames of the left view,a quality controller is adopted.Besides,a fuzzy controller is proposed to control the variation in quality between the left and right views by comparing the PSNR disparity of two views with a fixed threshold,which is used to quantize the binocular psycho-visual redundancy and adjust the quantization parameter (QP) of the right view correspondingly.The proposed algorithm has been implemented in H.264/AVC video codec,and the experimental results show its effectiveness in rate control while keeping a good quality for the left view,and fewer bits are allocated for the right view so that the overall bit rate is saved by 7.2% at most without the loss of subjective visual quality for stereoscopic video. 相似文献
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In this paper we introduce a framework for using quality as an incentive to promote proper application level congestion control. Through integrating a joint-source channel coder and feedback-based congestion control scheme, we are able to construct accurate and efficient quality incentives. The framework is applicable in all network architectures where end-to-end congestion control may be used, and is as such not specific to either best-effort or traffic class-based architectures. The concept is presented along with preliminary simulations that highlight the resulting rate control accuracy. We also discuss how to implement some well-known congestion control schemes within our framework. 相似文献
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In this paper we introduce a framework for using quality as an incentive to promote proper application level congestion control. Through integrating a joint-source channel coder and feedback-based congestion control scheme, we are able to construct accurate and efficient quality incentives. The framework is applicable in all network architectures where end-to-end congestion control may be used, and is as such not specific to either best-effort or traffic class-based architectures. The concept is presented along with preliminary simulations that highlight the resulting rate control accuracy. We also discuss how to implement some well-known congestion control schemes within our framework. 相似文献
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INTRODUCTION Real-time video transport over wireless Internet faces many challenges due to the heterogeneous en- vironment including wireline and wireless networks. Fig.1 shows a typical end-to-end video transport in- volving wireline and wireless networks. The video transport may suffer from many problems such as wireline network congestion and wireless multi-path fading, resulting in high packet loss-rate, and causing severe video quality degradation. To maintain the optimal video quali… 相似文献
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INTRODUCTION Streaming of multimedia data over the Internet has rapidly increased in recent years. All commercial applications and most research in video streaming use conventional hybrid video coding. To adapt the data transmission rate on the server to the varying bandwidth caused by congestion in the Internet or to different available bandwidths of different clients, the simulcast solution is widely applied (Balk et al., 2003; Feamster et al., 2001; Schierl and Wiegand, 2004). A larg… 相似文献
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黄凯锋 《牡丹江教育学院学报》2010,(5):108-109
本文主要以网络广泛应用的客户/服务器作为应用模型,在考虑网络状态的基础上,通过引入客户端缓冲区状态,提出了一种针对视频点播系统的流量控制机制。该机制将网络拥塞控制和客户端缓冲区控制策略结合起来对视频服务器发送速率进行自适应调整,保证了发送码率的平滑,更好地满足了客户端的需求,提高了网络带宽利用率。 相似文献
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INTRODUCTION Ad-hoc networks are attractive owing to their self-organizing nature and absence of a fixed infra- structure. They are particularly suited for communi- cation in disaster-affected areas, coordinating military operations, and sensing environmental conditions With the growing availability of supporting hardware and decreasing equipment cost, ad-hoc networking based applications are proliferating. Meshes of wire- less nodes are being deployed in cities and housing communities to… 相似文献
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网络中的拥塞来源于网络资源和网络流量分布的不均衡性。随着互联网规模的增长,互联网上的用户和应用都在快速的增长,如果不在互联网中使用拥塞控制算法,拥塞崩溃的发生会严重降低网络的性能。在互联网中使用有效的拥塞控制算法成为一个很有研究价值的重要课题。在比较了现有的拥塞控制算法及其优缺点,针对FRED算法提出了一种改进后的FRED算法、对算法进行了抓包实验,并且从服务质量及网络公平性原则方面做了进一步的研究与探讨。 相似文献
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随着经济的迅猛发展,人们生活水平的不断提高,机动车进入家庭的速度加快,导致机动车数量激增,从2005年末至2006年末,我国机动车保有量由8850万辆猛增到1.07亿辆,年增长率达到了20.9%。而我国道路增长速度远远落后于车辆增长速度,由此导致交通拥挤现象日益加剧。城市道路交通拥堵已经成为阻碍城市快速健康发展的一个主要问题。本文实现了将无线传感器网络应用到交通控制系统中,通过搭建无线传感器网络通信平台来将交通中的实体给联系起来,从而为进行提高城市交通信号控制效率提供一种新的方法。 相似文献
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This paper is concerned with a control method for an exoskeleton ankle with electromyography (EMG) signals. The EMG signals
of human ankle and the exoskeleton ankle are introduced. Then a control method is proposed to control the exoskeleton ankle
using the EMG signals. The feed-forward neural network model applied here is composed of four layers and uses the back-propagation
training algorithm. The output signals from neural network are processed by the wavelet transform. Finally the control orders
generated from the output signals are passed to the motor controller and drive the exoskeleton to move. Through experiments,
the equality of neural network prediction of ankle movement is evaluated by giving the correlation coefficient. It is shown
from the experimental results that the proposed method can accurately control the movement of ankle joint.
Project supported by the National High-Tech R&D Program (Grant No.2006AA04Z224), the Innovation Program of Shanghai Municipal
Education Commission (Grant No.08ZZ48), and the Shanghai Leading Academic Discipline Project (Grant No.Y0102) 相似文献
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本文针对MPEG VBR多媒体流量的特征,结合小波和卡尔曼滤波的特点,在新的网络流量预测模型的基础上,提出了一种新的多媒体流自适应带宽分配算法,并在NS仿真平台中实现该算法。结果表明,该算法能够有效避免网络拥塞,降低网络传输时延,减少数据丢包率,明显地提高了带宽利用率,具有较好的实时性,支持QOS。 相似文献
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为了提高传统方法生成交通拥堵指数（TPI）的准确率,引入一种基于经验模态分解（EMD）与Elman神经网络的组合模型实现交通拥堵指数预测。首先,利用EMD将TPI序列分解为不同时间尺度下的IMF分量和剩余分量;然后,通过偏自相关函数（PACF）计算各分量的滞后期数,以此确定各分量在Elman神经网络中的输入和输出变量;之后,通过上述方法计算出各分量预测值并相加;最后,计算出总预测结果。通过计算结果可知,EMD-PACF-Elman预测方法3个评价指标（平均绝对误差、均方误差、平均绝对百分误差）的计算结果与单一Elman神经网络模型、EMD-Elman神经网络模型、单一BP神经网络模型、EMD-BP神经网络模型相比都为最低,分别为0.562 4、0.598 9、0.110 7。因此, EMD-PACF-Elman预测方法可以有效地预测TPI,同时也为进一步预测交通拥堵趋势提供了依据。 相似文献
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A graphical and visual simulation system for the study of optical packet switching(OPS)nodes is accomplished.With the simulation system,the effect on physical performance-bit error rate(BER)due to a variety of factors such as the crosstalk parameters of OPS nodes,number of cascaded OPS nodes,length of optical output buffer,traffic load and fluctuation of amplitude of optical signals are evaluated.Reliability of the simulation system is proved by the analytical results obtained in all the above cases. 相似文献