【作者】 盘丽娜；

【导师】 黄生叶；

【作者基本信息】 湖南大学 ， 通信与信息系统， 2007， 硕士

【摘要】 随着网络应用的普及和通信业务的日益增长,数据、视频等业务逐渐成为当今通信发展的一大亮点。网络变得越来越繁忙,综合业务网络的性能研究成为焦点,保证用户服务质量(QoS)变得极其重要。网络模型呼叫阻塞概率的研究是保证用户服务质量的重要前提。长期以来,网络建模和分析以泊松分布和马尔可夫过程理论为基础,而近年来大量网络业务测量表明网络业务具有自相似特性,这种特征不能由传统模型描述。并且网络业务自相似特性对网络的分析、设计、控制和性能评价均具有重大的影响。理论上推测Kaufman递推公式对计算输入流是Poisson分布,服务时间分布函数的拉氏变换是有理函数的网络业务模型的呼叫阻塞概率是有效的,但对于服务时间呈Pareto分布的综合业务排队系统是否可行尚无定论。本文介绍了自相似过程的常见定义,描述了该随机过程在数学和物理上的若干特征,对服务时间呈Pareto分布的综合业务排队系统进行仿真,统计系统的呼叫阻塞概率,结果与Kaufman递推公式计算结果相符。为采用仿真方法深入研究自相似业务下的网络性能打下基础。现代通信网络规模急剧增长,网络资源管理和流量管理面临新的挑战。大规模综合业务系统容量的计算问题十分复杂且耗时相当长,这显然不能满足现代通信不可预测性和推动新服务不断发展应用的要求。本文把综合业务网络抽象为一个多类业务顾客、多服务员的队列,在基于准独立近似的呼叫阻塞概率快速算法的基础上,提出一种排队系统容量的快速近似算法。文中实例的计算结果表明这种方法计算的系统容量比较准确,且速度很快。为我们在复杂网络背景下研究宽带综合业务系统容量规划方法打下基础。更多还原

【Abstract】 In recent years, the network application becomes prevalent and communication services increase sharply. New services like data transport and video becomes hotspot in the development of communication. Since the network become more and more busy, It’s very significative to analyze the performance of integrated service network. Assuring the quality of service (QoS) of each user becomes very important according to the increase of the bearer services of network. Call blocking probability (CBP) is very important to determine the QoS of each user.For a long time, traffic modeling and performance analysis is based on Poisson distribution and Markov process. But recently measures of network traffic have shown the self-similar nature of network traffic. And this property can’t be described by traditional models. The characteristic of traffic has a great effect on the analysis, design, control, and performance evaluation of computer networks. The formula of Kaufman is speculated to hold for any system with Poisson arrival and general service time distribution. And the Laplace transform of service time distribution must be a rational function. But rigorous proof is absent to illuminate that whether the Kaufman formula can be applied to calculate the CBP of queuing system with integrated service. In this thesis, several mathematical definitions of self-similarity are given and some of their features are described. The simulation of integrated service system with Pareto service time distribution has been implemented. The simulation result coincides well with Kaufman formula. This lays the foundation of further research on using simulation methods to study the performance of networks with self-similarity traffic.With the scale of networks boosting in modern times, the resource and traffic management faces new challenges. It’ll take long time to calculate the CBP of large-scale networks with integrated service because of the complicated networks. And the traditional algorithm is not effective. In this thesis, an integrated service network is abstracted to a queuing system with integrated service. And a new algorithm is proposed to calculate the capacity of the queuing system based on an algorithm which calculates the CBP of quasi-independent system fast. As the instance showed, the algorithm is effective and short-time consuming. This lays the foundation of further research on programming network capacity under real and complicated background.更多还原