ATM网络中的变比特速率视频图像业务模型

选择合适的业务源模型是成功设计和建设未来高效ＡＴＭ网络的一个非常重要的因素。因此至今，已提出了大量的业务源模型。本文就目前提出的变比特速率视频图像（ＶＢＲＶｉｄｅｏ）业务的主要经典模型，作一分析评价，并给出业务模型较详细的参数和选择准则。最后，给出采用一业务模型检测了我们设计的模糊联合存储漏桶模型在网络系统中业务带宽监管性能     

ATM网中具有优先级管理的漏桶监管器性能分析

本文利用推广的流体流方法分析了具有优先级管理的ＡＴＭ网漏桶监管器（ＰＬＢ）性能。这种ＰＬＢ将部分缓冲共享（ＰＢＳ）的选择丢弃优先级策略用于业务监管，对高、低优先级信元区别对待，从而保证高优先级信元的低丢失率。文中针对突发业务分析了此种监管方案的性能。理论计算及体育场实验结果表明了方案的有效性，通过性能分析可望选取合适的ＰＬＢ参数进行有效控制。     

ECI光同步传输设备SDM4的故障处理

１单纤不好故障现象 :Ａ站列柜告警铃响 ,ＵＣＰ告警单元上ＭＡＪＯＲ灯亮（主要告警） ,同时用户反映至对端站（Ｂ站）的２Ｍｂｉｔ／ｓ电路阻断。故障判断及处理 :①查看Ａ站的ＥＥＭ（网元管理） ,发现本站一块光卡上有ＭＳ-ＦＥＲＦ（复用段远端接收失效）、ＶＣ４ -ＦＥＲＦ（ＶＣ４级远端接收失效）告警 ,Ｂ站的ＭＡＪＯＲ灯亮 ,因无ＥＥＭ故不能进一步查看告警内容。询问ＮＥＭ（网络管理） ,说Ｂ站已退出网管 ,也无法查看告警信息 ,要想判明障碍需做如下分析。②Ａ收到的ＭＳ -ＦＥＲＦ、ＶＣ３-ＦＥＲＦ是Ｂ站在收到ＭＳ-ＡＩＳ、…     

CHINESE JOURNALOFL ASERS B Vol. B4, No.1(Series No.19),February 20,1995

ＣＨＩＮＥＳＥＪＯＵＲＮＡＬＯＦＬＡＳＥＲＳＢＶｏｌ．Ｂ４，Ｎｏ．ｌ（ＳｅｒｉｅｓＮｏ．１９），Ｆｅｂｒｕａｒｙ２０，１９９５（Ｊａｎｕａｒｙ／Ｆｅｂｒｕａｒｙ）CHINESE JOURNALOFL ASERS B Vol. B4, No.1(Series No.19),February 20,199...     

ATM网络中的ABR业务在不同ON—OFF业务背景上的性能研究

本文比较研究了ＡＴＭ网络中的三种不同分布的ＯＮ－ＯＦＦ源对ＡＢＲ业务性能的影响;周期性的ＯＮ－ＯＦＦ源,长度为指数分布的ＯＮ－ＯＦＦ源以及长度为Ｐａｒｅｔｏ分布的ＯＮ－ＯＦＦ源,发现Ｐａｒｅｔｏ分布的ＯＮ－ＯＦＦ源对ＡＢＲ业务的性能影响最大,此时需要更大的缓存器存放在ＶＢＲ业务的ＯＮＭ期间累积的ＡＢＲ信元,为了改善性能,我们对ＰｒｅｔｏXＯＮ－ＯＦＦｉｄｒ ｆｊｔｆｂ ｇｕ ｉｍｅ ｔｈｇｊ２,ｇ     

ATM网络中的ABR业务在不同ONOFF业务背景下的性能研究

本文比较研究了ＡＴＭ网络中的三种不同分布的ＯＮＯＦＦ源对ＡＢＲ业务性能的影响;周期性的ＯＮＯＦＦ源,长度为指数分布的ＯＮＯＦＦ源以及长度为Ｐａｒｅｔｏ分布的ＯＮＯＦＦ源．发现Ｐａｒｅｔｏ分布的ＯＮＯＦＦ源对ＡＢＲ业务的性能影响最大,此时需要更大的缓存器存放在ＶＢＲ业务的ＯＮ期间累积的ＡＢＲ信元．为了改善性能,我们对ＰａｒｅｔｏＯＮＯＦＦ源进行了平滑处理,还在理论上对所得实验结果作了解释．     

ATM网络中漏桶流量控制特性的研究

本文对ＡＴＭ（异步转移模式）网络中话音、数据和图像业务的漏桶流量控制特性进行了研究。计算机模拟结果表明，由于各种业务内在的相关性不同，相应的漏桶流量控制特性有较大的差异。漏桶参数的选择对于各种业务具有不同的公平性，因而应根据业务的特性来设计漏桶参数。     

ATM网络中漏桶涌量控制特性的研究

本文对ＡＴＭ（异步转移模式）网络中话音、数据和图像业务的漏桶流量控制特性进行了研究。计算机模拟结果表明，由于各种业务内在的相关性不同，相应的漏桶流量控制特性有较大的差异，漏桶参数的选择对于各种业务具有不同的公平性，因而应根据业务的特性来设计漏桶参数。     

THE OUTPUT OPTICAL FIELD INTENSITY DISTRIBUTION FORMED BY AN OPTICAL FIBER END

ＴＨＥＯＵＴＰＵＴＯＰＴＩＣＡＬＦＩＥＬＤＩＮＴＥＮＳＩＴＹＤＩＳＴＲＩＢＵＴＩＯＮＦＯＲＭＥＤＢＹＡＮＯＰＴＩＣＡＬＦＩＢＥＲＥＮＤ￥ＹＵＡＮＬｉ－Ｂｏ（Ｄｅｐａｒｔｍｅｎｔｏｆｐｈｙｓｉｃｓ，ＨａｒｂｉｎＥｎｇｉｎｅｅｒｉｎｇＵｎｉｖｅｒｓｉｔｙ...     

模糊漏桶在ATM网络UPC中的应用

本文提出了模糊漏桶模型，研究了它与普通漏桶在用户量参数控制（ＵＰＣ）中的作用。由于ＣＡＣ初步协议的不完全合理性，在实际应用中动态调节是必要的；仿真结果表明在降低信元丢失率、时延和时延抖动方面，及在动态利用网络资源方面，模糊漏桶算法要比普通的优越。我们还给出了合适的模糊控制规则。     

A novel neural network traffic enforcement mechanism for ATMnetworks

ATM has been recommended by the CCITT as the transport vehicle for the future B-ISDN networks. In ATM-based networks, a set of user declared parameters that describes the traffic characteristics, is required for the connection acceptance control (CAC) and traffic enforcement (policing) mechanisms. At the call set-up phase, the CAC algorithm uses those parameters to make a call acceptance decision. During the call progress, the policing mechanism uses the same parameters to control the user's traffic within its declared values in order to protect the network's resources and avoid possible congestion problems. A novel policing mechanism using neural networks (NNs) is presented. This is based upon an accurate estimation of the probability density function (pdf) of the traffic via its count process and implemented using NNs. The pdf-based policing is made possible only by NNs because pdf policing requires complex calculations, in real-time, at very high speeds. The architecture of the policing mechanism is composed of two interconnected NNs. The first one is trained to learn the pdf of “ideal nonviolating” traffic, whereas the second is trained to capture the “actual” characteristics of the “actual” offered traffic during the progress of the call. The output of both NNs is compared. Consequently, an error signal is generated whenever the pdf of the offered traffic violates its “ideal” one. The error signal is then used to shape the traffic back to its original values     

Dynamic versus Static Traffic Policing: A New Approach for Videoconference Traffic over Wireless Cellular Networks

The subject of traffic policing for computer communication networks has been studied extensively in the literature. However, the constant development of new multimedia applications which are ldquogreedyrdquo in terms of bandwidth and Quality of Service requirements calls for new approaches to the traffic policing problem. In this work, we introduce a new video model for single H.263 videoconference sources and we use it in order to propose a new traffic policing approach for wireless videoconference traffic. We study well-known traffic policing mechanisms which still present interesting, unsolved problems when servicing video traffic and propose, to the best of our knowledge, for the first time in the relevant literature that the token generator is based on a traffic model and not on a fixed rate. The proposed approach shows significant improvement in the results obtained by all the traffic policing mechanisms, and hence, shows that dynamic traffic policing can provide much higher efficiency than the widely used static approach.     

ATM业务监控的最差通过流分析及二级漏桶算法

讨论了一定算法下最差通过流的概念，强调了最差通过流的参数特性是评价一种业务监控算法的重要指标之一。对基本漏桶和缓冲漏桶逄法进行了比较。     

Lowpass traffic policing mechanism based on the leaky bucket

A traffic throttle can be modelled as a gate with one input and two outputs: pass for accepted calls, and gap for rejected calls. The gate decides whether to pass or to gap an incoming call according to its policing mechanism. The authors show that a small modification to a leaky bucket policing mechanism yields a lowpass filter. The proposed mechanism is a new type of a nonlinear filter     

The effects of correlated arrivals at a server with credit‐based traffic policing

In this paper we observe the steady state and transient behaviour of correlated cell arrivals into a server with credit‐based traffic policing. We derive expressions for the lag‐k correlations of the departure process from the traffic policing mechanism, and observe how dependencies in the departure stream affect cell loss at the server. The results illustrate the impact of the second‐order statistics and the higher moments of the cell arrival processes on the traffic policing mechanism performance. Copyright © 2001 John Wiley & Sons, Ltd.     

A multifractual traffic policing mechanism

In this letter we Introduce a new traffic policing mechanism able to deal with multifractal sources. The ability of monitoring accurately a traffic flow is of extreme importance to avoid malicious behavior on the part of some users and to guarantee the required quality of service of other users. The proposed policing mechanism approximates an ideal algorithm.     

Policing of realistic VBR video traffic in an ATM network

ATM has been accepted by CCITT as the transport mechanism for the future BISDN and will also be widely used in future customer premises networks. Networks based on the ATM principle are expected to provide a very flexible communications infrastructure allowing customers to make effective use of a wide variety of offered services. To provide this flexibility with an acceptable quality of service while operating the network in an economic way, elaborate traffic management functions will be necessary to control the traffic flows within the network. This paper will study one of these functions—the so-called ‘usage parameter control’ or ‘policing’ function—in some detail to illustrate some of the problems that arise and point out possible solutions. The mechanisms chosen to implement the policing function will be the ‘leaky bucket’ mechanism, the ‘jumping window’ mechanism and the ‘moving window’ mechanism. The input streams used to assess the mechanisms represent different types of video communication—videophone, video conference and entertainment video—coded according to different variable bit-rate (VBR) algorithms. In contrast to most of the previous studies, where artificial, statistical traffic sources have been used, the sources used in this paper are directly based on measured ‘real-life’ video data. This ensures that all the statistical properties of the actual traffic stream are preserved and allows identification of the different factors that influence the dimensioning and the performance of the policing mechanism. The results of this study show that the uncertainty about the key parameters at call set-up and the considerable impact of single scenes make the proper dimensioning of policing mechanisms difficult. Furthermore, it seems not to be practical to use the long term mean bit-rate as the key traffic control parameter for these sources. Results indicating that the long-term cell loss ratio is not a sufficient measure for the quality of service are also presented. A comparison of the mechanisms shows that from a performance perspective, the ‘leaky bucket’ mechanism is superior to the two window mechanisms. This work is relevant to evolving standards for both BISDN traffic management and variable bit-rate video coding.