自相似混合业务流的网络性能研究

针对传统业务流量模型的网络性能结论不能完全适用于多路自相似业务混合流量的智能电力通信网络,首先介绍基于分形布朗运动的单一自相似业务流模型,接着分析多路输入自相似业务的合成流量模型,然后研究多路输入自相似流的网络性能,最后给出智能电力通信网中4类通信业务的QoS要求,其中通信业务的QoS要求和多路输入自相似混合流的网络性能计算,可为智能电力通信网的进一步研究提供参考。     

基于自相似业务模型的WCDMA接入性能分析

随机接入技术对WCDMA网络数据业务性能优化具有较大影响,文提出基于自相似业务模型的WCDMA接入技术并进行性能分析。仿真结果表明基于自相似业务模型的WCDMA网络数据业务接入性能与分形系数H值、网络负载G等参数有关。文章还提出了基于WCDMA的业务接入自相似均衡协议(TASEP),能明显改善WCDMA网络数据业务的接入性能。     

基于自相似业务的波长变换光网络性能分析

对自相似业务在波长变换光网络中的动态性能进行了研究,分析了在各种因素如自相似业务参数(Hurst参数、均值M、方差V)以及网络参数(光纤数F、波长数W)对自相似业务波长变换增益产生的影响,并对结果进行了讨论。     

GPRS QoS参数设置及其对移动数据业务的影响

随着移动宽带通信技术的发展,移动互联网业务日渐丰富,必须从网络角度最大化地保证业务的可用性。GPRS(通用分组无线服务)作为移动数据业务的承载网络之一将长期存在。文章深入研究GPRS网络中的QoS参数和端到端的QoS机制,围绕提升手机视频的用户感知,通过手机视频在不同QoS参数下的性能对比,验证了这些QoS参数对移动数据业务的影响。     

自相似模型下的交换式网络仿真

传统模式下的网络仿真,报文到达均服从的是一种具有短相关特性的泊松分布。而经过大量业务流量监测表明,网络流量实际呈现出的确是一种具有长相关特性的自相似分布,这种特性对网络流量建模、性能分析、接纳控制等产生了重要影响。在对自相似特性深入分析的基础上,利用分型布朗运动模型的RMD算法产生自相似序列来模拟网络业务,并对该业务流特性下的交换式以太网进行了仿真实验。结果表明业务量的自相似性对交换式网络的各项性能影响很大,这与传统流量模型形成鲜明对比。     

自相似业务流模型的分析与比较

在研究通信网络的流量控制及网络性能时，业务流模型是一个重要的组成部分。本文分析了几种自相似模型的特点，并指出了这几种自相似模型的区别以及这些模型所适用的网络业务流。它对自相似业务的分析和处理具有一定的指导意义。     

基于分形整形器的GPS系统性能确定上界研究

为了精确求解以自相似业务作为输入的网络性能确定边界问题,在GPS(generalized processor sharing)系统入口处利用分形整形器对自相似业务进行调控,提出了基于分形整形器的GPS系统模型,基于确定性网络演算理论推导了使用自相似业务作为输入时该GPS系统的缓存队列长度、延迟、延迟抖动以及有效带宽等性能确定上界模型。数值结果表明,基于分形整形器的GPS系统性能确定上界模型对自相似业务具有较好的性能。     

WDM光网络中支持QoS的波长分配算法

基于在波长可变光网络中的波长分层图模型,本文提出了一种在动态业务情况下的支持不同QoS要求的路由波长分配算法,根据客户层业务不同的QoS要求,通过分层图模型中参数的不同取值,对其光路建立请求区别对待,提供不同级别的光路建立.仿真结果表明该算法具有很好的性能,提高了全网的资源利用率,满足了客户层业务在建立光通路时不同的QoS要求对网络阻塞率的要求.     

基于FBM模型的自相似流量建模仿真

网络流量建模是网络规划与性能评价的重要基础,传统的业务模型大多基于泊松模型和马尔可夫排队模型,只具有短程相关性,随着网络业务的不断研究发现,实际网络业务流在很长的时间范围内都具有长程相关性,即一种自相似性。本文采用RMD算法和Fourier变换法对网络流量的自相似模型-FBM模型进行了建模及仿真研究,生成了所需的自相似流量序列。然后分别采用R/S法和方差时间图法对其进行自相似参数检测。结果验证了仿真算法所产生的序列存在着自相似性,并同时对RMD算法和Fourier变换法的优缺点进行了分析。     

数据业务自相似特性研究

合适的业务源模型能够在建立理论分析模型或进行系统性能仿真时,使网络系统性能评价更加准确。自相似特性是数据业务的重要特征。本文分析了自相似业务源的建模现状,深入讨论了如何将自相似模型应用于GPRS业务源建模。通过时间序列自相似特性分析工具SELFIS,对中国移动GPRS网络中从一个网关支持节点GGSN处采集的在单位时间内收到的字节数进行分析,得出GPRS数据业务具有较强自相似性的结论。     

基于业务感知的认知网络QoS自适应控制技术

文章研究并提出了基于业务感知的认知网络服务质量(QoS)自适应控制架构。该架构在智能业务感知和分类模型的基础上对数据包进行分类和识别,并借鉴控制理论通过基于端路协同的认知网络业务流QoS自适应控制机制实现对网络流量的控制。在认知网络环境下,该架构可以构建QoS的自动感知、分析、关联、反馈、决策、配置和实施机制,进行资源的优化调整分配,适应网络环境的变化,优化网络端到端的性能,保证用户的服务质量。     

On multimedia networks: self-similar traffic and networkperformance

The main objective in telecommunications network engineering is to have as many happy users as possible. In other words, the network engineer has to resolve the trade-off between capacity and QoS requirements. Accurate modeling of the offered traffic load is the first step in optimizing resource allocation algorithms such that provision of services complies with the QoS constraints while maintaining maximum capacity. As broadband multimedia services became popular, they necessitated new traffic models with self-similar characteristics. We present a survey of the self-similarity phenomenon observed in multimedia traffic and its implications on network performance. Our current research aims to fill the gap between this new traffic model and network engineering. An immediate consequence of this study is the demonstration of the limitations or validity of conventional resource allocation methods in the presence of self-similar traffic     

A novel framework for G/M/1 queuing system based on scheduling-cum-polling mechanism to analyze multiple classes of self-similar and LRD traffic

Provisioning guaranteed Quality of Service (QoS) in multiservice wireless internet is challenging due to diverse nature of end-user traffic (e.g., voice, streaming video, interactive gaming) passing through heterogeneous interconnected domains with their own policies and procedures. Numerous studies have shown that multimedia traffic carried in wireless internet possesses self-similar and long-range dependent characteristics. Nonetheless, published work on wireless traffic modeling is merely based on traditional Poisson traffic distribution which fails to capture these characteristics and hence yield misleading results. Moreover, existing work related to self-similar traffic modeling is primarily based on conventional queuing and scheduling combinations which are simple approximations.This paper presents a novel analytical framework for G/M/1 queuing system based on realistic internet traffic distribution to provide guaranteed QoS. We analyze the behavior of multiple classes of self-similar traffic based on newly proposed scheduling-cum-polling mechanism (i.e., combination of priority scheduling and limited service polling model). We formulate the Markov chain for G/M/1 queuing system and present closed form expressions for different QoS parameters i.e., packet delay, packet loss rate, bandwidth, jitter and queue length. We develop a customized discrete event simulator to validate the performance of the proposed analytical framework. The proposed framework can help in building comprehensive service level agreements for heterogeneous wireless domains.     

支持多优先级QoS的业务量疏导算法

针对当前业务量疏导研究中很少涉及的QoS约束的问题,提出并研究了一种支持多优先级QoS的业务量疏导算法（Differentiated Traffic Grooming Algorithm,DTGA）,该算法综合考虑了对不同等级业务QoS和网络资源利用率的优化。与目前实用的WDM光网络业务量疏导算法的性能仿真对比表明,DTGA能有效地降低高服务等级需求业务的阻塞率和节省网络资源。     

自相似网络通信量模型研究综述

越来越多的研究表明网络通信量不是Markov过程,而是在任意时间尺度上都具有突发特性,即自相似特性。描述网络通信量的数学模型主要有自相似和长相关结构。网络的某些参数服从重尾分布,从而导致网络通信量时间尺度上的突发特性。该文分析了传统网络通信量模型和性能分析的弊端,描述了新型网络通信量模型应该具有的基本特征。本文重点研究了网络自相似通信量相关的ON/OFF模型、用户访问概率模型和网络流量闭环模型,讨论了相关的研究方向,并总结了在研究网络通信量模型的过程中应该注意的原则和问题。     

Towards the formation of comprehensive SLAs between heterogeneous wireless DiffServ domains

Traffic patterns generated by multimedia services are different from traditional Poisson traffic. It has been shown in numerous studies that multimedia network traffic exhibits self-similarity and burstiness over a large range of time-scales. The area of wireless IP traffic modeling for the purpose of providing assured QoS to the end-user is still immature and the majority of existing work is based on characterization of wireless IP traffic without any coupling of the behaviour of queueing systems under such traffic conditions. Work in this area has either been limited to simplified models of FIFO queueing systems which do not accurately reflect likely queueing system implementations or the results have been limited to simplified numerical analysis studies. In this paper, we advance the knowledge of queueing systems by example of traffic engineering of different UMTS service classes. Specifically, we examine QoS mapping using three common queueing disciplines; Priority Queuing (PQ), Low Latency Queuing (LLQ) and Custom Queueing (CQ), which are likely to be used in future all-IP based packet transport networks. The present study is based on a long-range dependent traffic model, which is second order self-similar. We consider three different classes of self-similar traffic fed into a G/M/1 queueing system and construct analytical models on the basis of non-preemptive priority, low-latency queueing and custom queueing respectively. In each case, expressions are derived for the expected waiting times and packet loss rates of different traffic classes. We have developed a comprehensive discrete-event simulator for a G/M/1 queueing system in order to understand and evaluate the QoS behaviour of self-similar traffic and carried out performance evaluations of multiple classes of input traffic in terms of expected queue length, packet delay and packet loss rate. Furthermore, we have developed a traffic generator based on the self-similar traffic model and fed the generated traffic through a CISCO router-based test bed. The results obtained from the three different queueing schemes (PQ, CQ and LLQ) are then compared with the simulation results in order to validate our analytical models.     

网络业务量的一种稳定多分形模型及其检验

目前网络业务量研究中有自相似和多分形两种主要的先验模型。自相似模型简洁,运用单一的H 指数来描述业务量特性,但它并不能完全表达业务量的信息;多分形模型更准确,但它运用函数形式的多分形谱来刻画信号,不便于实际分析。本文在无穷可分层叠的理论框架下提出了网络业务量的一种稳定多分形模型。运用小波变换方法,通过多个业务量记录的检验,证实此模型从尺度行为和边缘分布两方面都能准确刻画业务量。作为一般多分形过程的特例,该模型把多分形指数的表达式确定下来,并归结为4个参数的估计。