State diagrams and steady-state balance equations for open queuing network models

In this paper, the state diagrams and steady-state balance equations for two kinds of open queuing network models are presented. The first model comprises a network of single queues with single servers, while the second model comprises multiple servers for single queues. State diagrams are drawn for (2, 3) queuing networks with (i) single servers and (ii) multiple servers. Steady-state balance equations are derived from the state diagrams. The paper provides a method to solve open queuing networks by analyzing the stochastic process involved in the transition of states in a continuous time Markov chain which represents the state diagram of a queuing system.     

Generalization of queueing network product form solutions tostochastic Petri nets

A new solution is given for the steady-state probability computation of closed synchronized queuing networks. A closed synchronized queuing network is a particular Markov stochastic Petri net (a bounded and monovaluated Petri net with a strongly connected reachability graph and constant firing rates independent of markings). It is shown that the steady-state probability distribution can be expressed using matrix products. The results generalize the Gordon-Newell theorem. The solution is similar to the Gordon-Newell product form using matrix and vectors instead of scalars. A prototype solver developed from this result is presented     

A hybrid closed queuing network model for multi-threaded dataflow architecture

In this paper, a closed queuing network model with both single and multiple servers has been proposed to model dataflow in a multi-threaded architecture. Multi-threading is useful in reducing the latency by switching among a set of threads in order to improve the processor utilization. Two sets of processors, synchronization and execution processors exist. Synchronization processors handle load/store operations and execution processors handle arithmetic/logic and control operations. A closed queuing network model is suitable for large number of job arrivals. The normalization constant is derived using a recursive algorithm for the given model. State diagrams are drawn from the hybrid closed queuing network model, and the steady-state balance equations are derived from it. Performance measures such as average response times and average system throughput are derived and plotted against the total number of processors in the closed queuing network model. Other important performance measures like processor utilizations, average queue lengths, average waiting times and relative utilizations are also derived.     

Dynamic control of service rates in queuing networks

A method for dynamic control of service rates in closed exponential queuing networks is proposed. The performance of queuing networks with the service-rate control is analyzed, and the main steady-state network characteristics are computed using an analytic approximation. A simple example of a queuing network with controlled service rates is considered as an illustration. The efficiency of the service-rate control is confirmed by Monte Carlo simulations, which, as a by-product, also show acceptable accuracy of our analytical approximations.     

Guaranteed real-time communication in packet-switched networks with FCFS queuing

In this paper, we propose a feasibility analysis of periodic hard real-time traffic in packet-switched networks using first come first served (FCFS) queuing but no traffic shapers. Our work constitutes a framework that can be adopted for real-time analysis of switched low-cost networks like Ethernet without modification of the standard network components. Our analysis is based on a flexible network and traffic model, e.g., variable-sized frames, arbitrary deadlines and multiple switches. The correctness of our real-time analysis and the tightness of it for network components in single-switch networks are given by theoretical proofs. The performance of the end-to-end real-time analysis is evaluated by simulations. Moreover, our conceptual and experimental comparison studies between our analysis and the commonly used Network Calculus (NC) shows that our analysis can achieve better performance than NC in many cases.     

TCP/RED离散模型分析及参数设置

随机早期检测(RED)队列管理算法的参数设置主要依赖于使用者的经验,并且其相关理论指导存在一定缺陷。为此,提出一种全面设置RED参数的方法。采用数学期望方法,分析TCP/RED拥塞控制机制离散模型的稳定状态行为,推导网络稳定状态期望值与RED参数的解析关系式。仿真结果表明,该方法可以提供准确有效的RED参数设置。     

Controlling load distribution in the queuing systems

A method to control load distribution in the closed exponential queuing networks with one class of customers was proposed. It is based on simultaneous use of routing control and control of servicing intensities. Consideration was given to an evolution model of the queuing network with control of load distribution and an approximate method of analysis of the queuing networks of this type. A technique to calculate the stationary distribution and formulas to calculate other stationary characteristics of the queuing networks with control of load distribution were described. Examples of analysis of the queuing networks of this type were presented.     

一种自相似网络可靠性分析模型

利用ON/OFF模型产生自相似流量,提出了一种基于排队延迟的自相似网络可靠性分析模型。将节点和到达信息流视为G/M/1/B排队模型,利用大偏差理论得到节点平均排队延迟时间,进而得到网络各种工作状态下全网平均排队延迟时间。再利用延迟阀值得到各种工作状态下的网络可靠性,进一步得到全网可靠性。通过模拟计算,得到了给定拓扑结构网络的可靠性与自相似程度、ON/OFF源数量以及节点缓存大小之间的关系。     

基于排队网络的卫星应用信息链节点资源配置方法

针对卫星应用信息链的研究,给出一种基于排队网络理论的卫星应用信息链模型,确定相关的基本参数。分析在排队网络理论下卫星应用信息链节点的资源配置问题,并提出基于排队时间感知的节点资源配置优化算法,对信息链节点资源进行合理配置。     

短波令牌环协议排队模型的分析与优化

短波通信在短波无线IP令牌环协议网络中存在信道利用率低、令牌周期内数据传输总量小等问题。针对短波数据传输的特点,提出一种优化的短波令牌环网络IP网关数据输入排队模型。理论研究和仿真比较结果表明,该模型能解决信道中资源浪费的问题,实现高优先级数据的优先处理,有效提高网络的数据吞吐量。     

多服务器排队网络的规则行为

考虑由多服务器和任务队列网络组成的切换流网络,任务流从外部流入网络节点缓存 的速率是随机的,每个网络节点处任务流由指定的共享服务器按不同速率移向唯一的下游节点 缓存内.当随机任务到达流符合有界性或周期性统计规律时,本文给出了网络动态具有稳定的 规则行为的判别条件.     

Pareto-Optimal Sustainable Transportation Network Design under Spatial Queuing

This paper presents a multi-objective network design problem with environmental considerations for urban networks with queues. A spatial queuing link model is introduced to take account of the spatial effect of queuing. With this more realistic link performance function capturing spatial queuing, the network equilibrium flow patterns can be more accurately identified. Furthermore, to better estimate vehicle emissions, this paper proposes a refined emission estimation model, which distinguishes between travel speeds in free-running state and queue-forming state over a link. A multi-objective bi-level programming is then developed, in which the upper-level problem optimizes the investment decisions, whereas the lower-level problem characterizes the user equilibrium with spatial queuing delays. The metaheuristic of non-dominated sorting genetic algorithm II (NSGA-II) is adopted to solve the multi-objective network design problem. Numerical tests on the Sioux Falls network and the Barcelona network confirm the effectiveness of our proposed model and algorithm in identifying queuing equilibrium flows and Pareto optimal solutions. The refined models and valuable information about trade-offs among objectives are particularly helpful for environmentally sustainable transport network planning.

     

SNAPL/1: A language to describe and evaluate queuing network models

Recent theoretical developments in queuing theory have made multiclass queuing network models a viable alternative to established simulation methods for the analysis of dynamic systems. Computer software is required to describe and solve such network models. This paper describes a language which provides the human interface to a particular multiclass queuing network modelling package. The discussion is illustrated with an example from the language and concludes with suggestions for improvements.     

排队网络在制造系统中的应用及其三维仿真实现

首先讨论了排队网络建模仿真工具的功能需求，提出了基于有向图的排队网络仿真建模机制，以及将面向对象与离散事件结合起来的仿真方法，根据排队网络的理论，结合图形建模方法和动画仿真技术的发展，研究了排队网络法的3D仿真实现，开发了一个面向制造系统和基于3D仿真的排队网络分析工具。     

QoS enhancements and performance analysis for delay sensitive applications

This paper presents a comprehensive system modeling and analysis approach for both predicting queuing delay and controlling average queuing delay of a single buffer to a required value in a multiple traffic source network environment. This approach could effectively enhance the QoS performance of delay sensitive applications. A discrete-time analytical model that approximates the multi-source arrival process with a binomial distribution has been developed to analyze the relationship between the queuing threshold and average queuing delay. A control strategy with dynamic queue thresholds based on the analytical result is then used to control the average queuing delay to a required value within the buffer. Packet dropping is treated as implicit congestion feedback to the arrival process for rate adjustment. The feasibility of the system has been validated by comparing theoretical analysis with a diverse set of simulation results. Following from the simulation results, a set of statistical analyses has been performed to evaluate the efficiency and accuracy of the proposed scheme. In addition, a user-friendly graphical user interface has been developed to allow user-configuration of the simulation process and display simulation results.     

变码率视频流的排队网络分析

作为多媒体服务的主要组成部分,视频数据传输的性能评估是多媒体传输系统性能评估的核心内容。文章首先介绍了泊松点过程驱动的随机微分方程的相关数学理论,然后以变码率(VBR)视频的排队网络为实际应用背景,使用这种数学工具建立系统的排队模型,并进行了针对队列一阶距的性能评价分析。通过深入的理论分析,文章给出了针对视频传输方案性能改进和性能评估的有益结论,并给出了一种可能的队列各阶距的估算方法。     

Effects of Baggage Volume and Alarm Rate on Airport Security Screening Checkpoint Efficiency using Queuing Networks and Discrete Event Simulation

This study used queuing networks and discrete event simulation (DES) to investigate the effects of baggage volume and alarm rate at the security screening checkpoint (SSCP) of a small origin and destination airport. A queuing network was applied for theoretical modeling of the SSCP performance, and a DES model using Arena Version 12 was used for an empirical approach. Data were collected from both literature and by manual collection during the peak operating time of the airport that was modeled. The simulation model was verified and validated qualitatively and quantitatively by statistical testing before experimentation. After validation, a sensitivity analysis was performed on baggage volume of passengers (PAX) and the alarm rate of baggage screening devices, where SSCP throughput and PAX cycle time, were the dependent measures. The theoretical queuing network proved an accurate method of predicting cycle time for the system while in steady state but was subject to various assumptions. The empirical model and sensitivity analysis showed that SSCP throughput and cycle time are both highly sensitive to alarm rate. Additionally, the sensitivity analysis showed that SSCP throughput was completely resilient to baggage volume, while cycle time was moderately sensitive to baggage volume. Practical implications and future research were also discussed.     

典型AQM算法的性能评价模型

利用GI/M/1/N排队系统和Internet业务流量自相似性的特点建立了一个评价AQM算法在非响应业务流量下性能的分析模型,提出了利用模型的分析计算结果而不是模拟或实验手段评价AQM算法性能的新方法.同模拟或实验手段相比,该方法能更深刻地刻画AQM算法在实际网络环境中的性能.用该模型分析比较3个经典的AQM算法——TD、RED和GRED的性能,所得的结果同其他研究者利用模拟或实验方法所得的结果一致.     

共享存储器交换机的性能分析

交换机是分组网中的一个重要组成部分,对于分组网的性能有着很大影响。介绍共享存储器交换机的三种不同实现方法以及多播的实现过程．同时以排队论的知识为理论分析基础,介绍排队论中的生灭过程模型,状态转移模型和爱尔兰呼损模型,并对状态转移的稳态特性以及共享存储器结构的交换机的丢包率公式给出推导。对所做的工作做简要的总结,并指明未来的研究重点．