多优先级业务通信网的阻塞性能分析算法

最短径通信网和多抢占优先级服务方式的研究对于网络规划和减少重载时的业务损失有重要意义。本文利用抢占优先级服务方式的特性和文献［１］的研究结果，建立所研究的具有任意种不同优先级业务最短径通信网的数学模型，导出不同优先级业务通信网点对点阻塞概率的迭代算法，并利用所得到的算法对一个通信网的性能进行了实例分析。本文给出的算法适用于任意多抢占优先级业务下的任意拓扑结构网络。     

基于输入缓存机制的ATM网络优先级流控策略

提出一种基于输入缓存机制的ＡＴＭ网络优先级流控策略，并运用系统仿真技术对采用该优先级流控及ＦＩＦＯ输入流控两种方案的ＡＴＭ多媒体网络性能进行计算机仿真研究。结果表明：采用优先级流控策略将改善ＡＴＭ多媒体网非实时信元丢失率及实时信元排队时延性能，具有较大实用价值。     

基于输入缓存机制的ATM网络优先级流控策略

提出一种基于输入缓存机制的ＡＴＭ网络优先级流控策略，并运用系统仿真技术对采用该优先级流控及ＦＩＦＯ输入流控两种方案的ＡＴＭ多媒体网络性能进行计算机仿真研究。结果表明：采用优先级流控策略将改善ＡＴＭ多媒体网非实时信元丢失率及实时信元排队时延性能，具有较大实用价值。     

支持DiffServ的流量工程体系中最小化抢占的路径选择策略

在支持具有不同优先级和不同QoS需求的多业务网络中,抢占是带宽分配和管理的有效策略,但抢占也对网络造成了振荡。在路由策略中引入抢占信息可最小化重路由,提高网络的稳定性。本文在分析MPLS网络现有路径选择策略和抢占策略的基础上,提出一个最小化抢占的带宽约束路径选择算法。其基本思想是在路径选择中考虑低优先级LSP的资源预留信息,在链路开销函数中引入抢占信息即将被抢占的带宽和将被影响的最高优先级。我们的算法能在最小化抢占和重路由的同时实现负载均衡,有效地改善全局网络性能。     

支持DiffServ的流量工程体系中最小化抢占的路径选择策略

在支持具有不同优先级和不同Qos需求的多业务网络中，抢占是带宽分配和管理的有效策略，但抢占也对网络造成了振荡。在路由策略中引入抢占信息可最小化重路由，提高网络的稳定性。本文在分析MPLS网络现有路径选择策略和抢占策略的基础上，提出一个最小化抢占的带宽约束路径选择算法。其基本思想是在路径选择中考虑低优先级LSP的资源预留信息，在链路开销函数中引入抢占信息即将被抢占的带宽和将被影响的最高优先级。我们的算法能在最小化抢占和重路由的同时实现负载均衡，有效地改善全局网络性能。     

具有k种不同优先级话务流链路的性能分析

为改善网络性能，优先级服务方式已广泛应用于电信技术的各个领域，抢占优先级服务方式在军用通信网中的应用更具有重要的地位，Ｗａｎｇ和Ｓａａｄａｗｉ讨论了具有两种抢占优先级话务流链路性能的分析方法。本文将之拓展到具有任意ｋ种抢占优先级话务流链路性能的分析，导出对应的ｋ维稳态平衡方程的一般形式，并利用抢占优先级的特性提出求解状态方程组的有效方法，使用高斯消元法时，该方法可大大降低列式的阶；使用ＳＯＲ法时，     

策略驱动网络

校园网或企业网中的许多网络设备都能够设置服务策略、安全策略、信息流优先级分配策略等,在整个网络范围内保持各种设备控制策略的一致性并能够针对特定用户的特定应用动态改变控制策略是面向应用网络的基本要求。本文详细介绍了策略驱动网络功能、结构及3Com实现策略驱动网络的方法,并给出一个实例。     

OBS网络中基于优先级抢占的恢复机制

提出一种新的支持光突发交换网络中优先级抢占的快速恢复机制.该机制对不同优先级的业务采取不同的恢复策略,实现故障的快速恢复.同时采用阈值检测方式支持优先级抢占,减少受影响链路中较高优先级业务的丢包.仿真结果表明,基于优先级抢占的恢复机制具有较低的丢包率,对高优先级业务丢包率性能改善更为明显.     

MPLS网络中的自适应接入抢占策略

本文提出了一种在MPLS网络中进行自适应接入控制的抢占策略.该策略通过对已接入的低优先级LSP的QoS的降级来保证新接入的高优先级的LSP的接入请求.在进行降级时考虑了被降级的LSP的优先级、释放的带宽资源和LSP的降级比例.仿真结果表明,该抢占策略能提高网络的带宽利用率,减少LSP被重路由的代价.     

IP over WDM光网络中的业务疏导机制研究

针对当前IP overWDM光网络中业务量疏导技术研究的问题,提出了一种新的支持多优先级服务质量的业务疏导机制。该机制结合了抢占和流量分割技术,能够基于业务流QOS的需求选择恰当的疏导路径。仿真结果表明,该机制能有效降低具有时延约束的高优先级连接请求阻塞率。     

准静止状态下的高空平台实时业务信道分配

受平台准静止状态的影响,高空平台（ HAPS)通信网络内存在大量的切换呼叫,且业务量动态变化。 HAPS网络可传输多种业务,其中实时业务在切换过程中具有较高的时延要求。通过为切换呼叫预留信道可降低平台不稳定对服务质量（ QoS)造成的影响。在基于服务优先级的多业务信道分配算法基础上,重点对实时业务的信道分配算法进行改进,提出了一种基于概率的预留信道借用策略。该算法可根据网络内业务量的实时统计数据控制新呼叫业务的准入。仿真结果表明：与固定预留信道算法和门限预留信道算法相比,该算法能够适应网络内业务量的动态变化,在保证切换呼叫掉线率满足期望值的条件下提升系统的整体性能,降低平台不稳定造成的性能损失。     

离散时间闸门式多级门限服务的两级优先级轮询排队系统分析

本文提出了一种基于闸门式多级门限服务的两级优先级轮询系统.论文先构建了系统的排队分析模型,然后把模型中各个站点内的等待顾客数合起来设定为系统状态变量,对系统状态变量的概率母函数求二阶偏导后组成迭代方程组,联立求解后得到了站点的平均排队队长、顾客平均等待时间以及服务器查询周期等关键指标的完整数学解析表达式.最后,对该模型进行了仿真实验分析,实验结果与理论结果相一致.系统性能分析表明该轮询系统满足了周期性系统服务资源分配过程中业务多样性和弹性服务的发展需求,使得轮询控制策略应用方面更为广泛.     

离散时间并行优化门限服务轮询系统排队特性解析

针对周期式查询门限服务中流水线式调度效率低的问题，本文提出了一种并行优化门限服务轮询控制的系统服务资源调度策略.论文构建了轮询排队系统及其数学模型，先对系统状态变量的概率母函数求偏导得到一阶和二阶特性参数方程组，联立求解后推导出各个系统参数的完整数学解析表达式.仿真实验结果和理论计算值相一致.系统性能分析表明，该系统的队长和时延特性均得到了较大的提高，能够更好的适应密集数据环境下时延敏感性数据的服务需求.     

A Differentiated Service Model for Enhanced Distributed Channel Access (EDCA) of IEEE 802.11e WLANs

In this paper, we propose a new differentiated service model, referred to as Differentiated Service-EDCA (DS-EDCA), for the Enhanced Distributed Channel Access (EDCA) of IEEE 802.11e wireless local area networks (WLANs). With DS-EDCA, both strict priority and weighted fair service can be provided. The strict priority service is provided for high priority traffic through carefully setting the EDCA parameter sets of lower priority traffic; the proportional fairness service is enabled by determining the backoff intervals according to the distributed scheduling discipline (DFS). We also propose a hierarchical link sharing model for IEEE 802.11e WLANs, in which AP and mobile stations are allocated different amounts of link resource. The performance of DS-EDCA and EDCA is compared via ns-2 simulations. The results show that DS-EDCA outperforms the original EDCA in terms of its support for both strict priority and weighted fair service. More importantly, DS-EDCA can be easily implemented, and is compatible to the IEEE 802.11 Standard.

Network queue scheduling algorithm based on self-similar traffic level grading prediction

Self-similarity characteristic of network traffic will lead to the continuous burstness of data in the network.In order to effectively reduce the queue delay and packet loss rate caused by network traffic burst,improve the transmission capacity of different priority services,and guarantee the service quality requirements,a queue scheduling algorithm P-DWRR based on the self-similarity of network traffic was proposed.A dynamic weight allocation method and a service quantum update method based on the self-similar traffic level grading prediction results were designed,and the service order of the queue according was determined to the service priority and queue waiting time,so as to reduce the queuing delay and packet loss rate.The simulation results show that the P-DWRR algorithm can reduce the queueing delay,delay jitter and packet loss rate on the basis of satisfying the different service priority requirements of the network,and its performance is better than that of DWRR and VDWRR.     

Comparison of different congestion control strategies for low priority controllable traffic in packet switched backbone networks

It is expected that a significant part of the data flows of future multi‐service packet switched backbone networks will use low priority, non‐real‐time data transmission services of the networks. The common benefit for both user applications and network operators is that the data flows of the low priority services could use the free capacity of the networks, after the load of higher priority data flows. Congestion control methods are needed for these low priority data flows to reach an optimal utilisation level of the networks, high throughput and low packet loss ratios. This kind of low priority data transmission service which adjusts the data rates of the data flows according to the data rate changes of higher priority data flows, but does not guarantee any specific service for these data flows, is called a controlled load service. In this paper, we have compared the performance, efficiency and scalability of four different congestion control methods designed for the controlled load service. Two of these methods were based on very simple congestion control algorithms and the other two used relatively complex control algorithms based on control methods utilising computational intelligence. The principal aim of this study was to research how remarkable were the effects that the different complexities of the congestion control methods had on the achieved level of service. The simulation tests indicate that the complexity of the methods clearly affects the performance and efficiency of the methods. Copyright © 2001 John Wiley & Sons, Ltd.     

分级指导随机提早丢弃队列管理机制CGRED

本文提出的分级指导随机提早丢弃CGRED是在因特网上为用户提供有区别服务的单队列管理机制,它同时满足了对服务质量的精细控制和实现简单性两方面的需求.CGRED采用在线测量的方法跟踪业务类的实际带宽占用情况,根据给定的优先级关系确定调整业务类的指导策略,并以采用自适应算法计算得到的丢弃指导概率作为分组丢弃概率的边界,成功地解决了将不同业务类的实际带宽占用情况转化成如何丢弃不同业务类分组的实际操作.仿真结果表明CGRED是一种能有效提供DiffServ的实用网络控制机制.     

OOPN下基于优先级算法的Web服务组合

结合面向对象技术和Petri网技术的优点,将Web服务映射为一个对象,把对象抽象为一个方法的集合,通过对象的输入输出消息接口在方法层上讨论Web服务的组合.给出第一、第二优先级的定义,设计一个优先级算法,根据优先级能够选择出最佳的Web服务进行组合,从而得到最优组合Web服务,满足用户的服务请求.最后,给出一个Web服...     

On Supporting Weighted Service Differentiation in Multi-Packet Reception Wireless Networks: A Distributed Tree-Based Approach

The conventional medium access control (MAC) protocols assume that only one packet (frame) can be received at a given time. However, with the advent of spread spectrum, antenna arrays, and sophisticated signal processing techniques, it is now possible to achieve multiple-packet reception (MPR) in wireless networks. With MPR, the network capacity can be remarkably increased, but so far, how to achieve fair bandwidth allocation for the stations with different quality of service (QoS) requirements in such networks is still a problem. To solve this problem, we propose a distributed method that can support multiple priority classes in the MPR-capable wireless networks with weighted fair share. In particular, this method assigns each class a frame transmission probability to reflect its relative weight among the different data traffic flows. A closed-form expression of system throughput is derived for each class in the environment, and it is numerically evaluated with different simulation scenarios. The results show that the method can achieve the weighted fairness under different numbers of priority classes and different numbers of stations in the networks.     

基于DynamipsGUI的网络服务质量实验设计

为了验证服务质量在解决网络带宽不足方面的作用，采用DynamipsGUI搭建网络环境，配置优先级队列，模拟了relnet以及大小为15000字节的数据从路由器转发时，路由器根据优先级队列将数据报文从不同队列转发的过程。实验表明，服务质量能够在一定程度上解决网络带宽不足的问题。