集合点平均值分析方法的分布式系统应用

为了解决分布式系统的性能评价问题.描述了一种基于分层排队网络模型的分布式系统性能预测方法,提出一种分析分层排队网络模型的方法——集合点平均值分析(RMVA)方法来计算平均响应时间、平均吞吐量等性能参数.以DBMS为例建立了DBMS的分层排队网络模型,通过模拟实验验证了该模型及算法的合理性及有效性.     

基于输入队列的光分组交换短包抢先调度

光分组交换的输出队头阻塞引起分组的平均排队时延增加.分析了可变长分组的特点,提出了基于抢先方式的短包抢先调度(PSPP)算法,以减少分组在输入排队中的平均等待时间.在PSPP算法中,短包可以抢占长包的传输时间,获得优先的服务.分析和仿真结果表明,当到达业务负载为中或较低时,短包优先调度算法使短包的平均排队时延接近零,所有分组的平均等待时延减小,该算法还保证具有实时特性的TCP业务获得较低的平均等待时延.     

移动Ad hoc网络轮询接入控制协议

该文对Ad hoc网络的MAC层协议进行了研究,通过对无线令牌环协议(WTRP)进行改进,提出了一种新的具有QoS保障的无竞争的分布式并行无线轮询访问协议(DPWPAP),并采用嵌入Markov链和概率母函数的分析方法,用限定服务规则进行了系统建模,在系统模型的基础上得到了系统的平均排队队长以及平均等待时间的解析结果.理论分析和仿真结果是一致的,表明该协议的排队等待延迟和平均等待队列长度均比WTRP有很大降低,稳定性大大增强,更加适用于对时延要求较高的业务.     

基于TDMA的临近空间通信网MAC层协议仿真

运用网络仿真软件OPNET Modeler10.5作为开发环境,建立了临近空间通信网模型,设计了媒体接入控制(MAC)层的时分多址(TDMA)接入协议,实现了各个地面站对临近空间物理链路资源的有效共享.利用排队理论推导了该协议下的平均网络时延计算公式.收集的仿真结果表明,理论分析能够较准确地估计平均网络时延.     

未来全光网络的发展

运用排队论的知识 ,从理论上分析比较了在排队时光时分复用技术 (OTDM)较波分复用技术(WDM)在逗留时间上更具有优势 ,指出未来全光网的建设应该走 OTDM和 WDM结合的道路。     

光突发交换中的JET协议

介绍了光突发交换(OBS)中JET协议的基本概念以及JET协议实现时需要考虑的因素，用排队论模型求得了JET协议下OBS网络的突发包丢失率，并分析了OXC配置时间和突发包平均长度对突发包丢失率的影响。     

现代通信研究中的排队理论

从现代通信研究的角度出发,探讨排队理论发展的有关问题,分析了现代通信系统中排队的特点,还介绍了现代通信研究(特别是ATM研究)中常用的排队分析方法。     

两类周期查询式完全服务排队系统研究

本文对时间连续型非对称周期查询式完全服务排队系统进行了分析,并与时间离散型周期查询式完全服务排队系统(赵东风,1994)进行了对比研究。在两种系统取相同的系统参数值的条件下,给出两类排队服务系统的分析结果。     

智能排队信息系统

本文研究采用图像识别技术实现排队信息查询系统。该系统通过采集当前排队通道的照片或视频,识别排队队列的人数,并计算队列的前进速率、排队时长、队伍人数变化速度和平均排队人数。同时,系统还能存储、记录和保存识别计算结果,并预测当天的最佳时间段、预测总排队时长和预测排队总人数。用户可以通过查询该系统获取排队信息,包括查询队列的人数、队列的前进速率、排队时长、队伍人数变化速度、平均排队人数、最佳时间段、预测总排队时长、预测排队总人数以及用户自身排队记录。通过该系统自动预估排队信息,用户能实时了解最佳的排队时机。     

基于排队论的地铁站自动检票机配置研究

分析了地铁站乘客到达自动检票机处等待检票的排队过程,建立了地铁站自动检票机数量合理性的评价指标,并对实际案例进行了研究,记录地铁站高峰时段乘客的排队过程,统计乘客到达自动检票机处排队接受服务的时间间隔,验证地铁站乘客到达分布服从负指数分布,基于排队理论,求得乘客的平均排队长度和平均等待时间,从而对自动检票机的数量进行了评价与优化。该方法可以降低地铁站检票机的配置成本和乘客的等待时间,提高经济性与服务质量。     

PERFORMANCE ANALYSIS OF POLLING SYSTEMS WITH LIMITED SERVICE

This paper analyzes a queue mode] of the polling system with limited service (K=1) in discrete time. By the imbedded Markov chain theory and the probability generating function method, the mean values of queue length and message waiting time are explicitly obtained. Also, we give the simulation results. The results obtained by H. Tagai (1985) are revised.     

Approximations of Queue Dynamics and Their Application to Adaptive Routing in Computer Communication Networks

Various adaptive algorithms have been proposed for routing, flow and congestion control in packet-switched computer communication networks. In most of them, information on queue lengths, or equivalently, time delays, at various points in the network is required for proper adaptation. Since up-to-date information is not always available, these quantities must be estimated based on prior information. This paper presents approximations for the dynamic behavior of theM/M/1queue which is used to yield the desired estimates of queue lengths. Based on the assumption of finite (but arbitrarily large) storage, a closed form expression for the evolution in time of the queue length distribution is obtained. From this expression various approximations for estimated queue length are extracted. A simple expression for the "relaxation time" of the queue is also deduced as a function of utilization factor and service time. The approximations are applied to a simple adaptive routing example in which packets are routed along the transmission path having the shortest estimated queue, based on delayed information.     

Stationary characteristics of an M 2 X /M/n queue with hysteretic control of the input flow intensity

A multichannel queueing system with an unlimited queue length is considered. In the system, the service time and time intervals between arrivals of customer batches are characterized by exponential distributions and a hysteretic mechanism is applied to control the input flow intensity. The system receives two independent types of flows of customers one of which is blocked in the overload mode. An algorithm for determination of the stationary distribution of the number of customers and the stationary characteristics (the mean queue length, the mean time of waiting in the queue, the probability of a loss of customers) is proposed. The obtained results are verified with the help of a simulation model developed with the help of the GPSS World tools.     

Switched bath Bernoulli process (SBBP) and the discrete-timeSBBP/G/1 queue with application to statistical multiplexer performance

A doubly stochastic point process is proposed and analyzed. It is a switched batch Bernoulli process (SBBP) for modeling bursty and correlated input to discrete-time queuing systems. Through the investigation of the counting process, statistical characterization measures of the SBBP are explicitly obtained. A discrete-time single-server queue with SBBP input and general service time (SBBP/G/1) is then considered. The SBBP/G/1 queue has a potential applicability to a statistical multiplexer in the network. The supplementary variable technique is used to obtain the probability generating functions of performance measures in the SBBP/G/1 queue. It is shown how the SBBP is suitable for analyzing a discrete-time queue with bursty and correlated input     

The superposition of periodic cell arrival streams in an ATMmultiplexer

The authors consider the queue arising in a multiservice network using ATM (asynchronous transfer mode) when a superposition of periodic streams of constant-length cells is multiplexed on a high-speed link. An exact closed formula is derived for the queue length distribution in the case where all streams have the same period, and tight upper and lower bounds are obtained on this distribution when the periods are different. Numerical results confirm that the use of a Poisson approximation (i.e. the M/D/1 queue) can lead to a significant overestimation of buffer requirements, particularly in the case of heavy loads. Buffer requirements for a mixture of different period streams can be accurately estimated from the upper bound on the queue length distribution. For given load, requirements increase with the number of long-period (i.e. low-bit rate) sources. The results are deduced from a novel characterization of the single-server constant service time queue, which should be useful in other applications     

Handover prioritizing scheme for reducing call failure probability in cellular wireless network

This paper proposes a scheme suitable for managing handover in wireless cellular network. The main objective of the proposed scheme is to reduce the probability of forced termination of ongoing call due to handover failure. The scheme employs a queuing discipline, and the priority of queued is based on the residual time of the mobile user in the overlap region between two adjacent cells, assuming that the user's location and speed can be determined, then we applied the ascending priority; it means that the users having a shorter residual time join the head of the queue (i.e., high priority) while those having longer residual time at the end of the queue (i.e., low priority). Fixed channel allocation strategy (FCA) is employed and simulation results obtained concern: call blocking probability (CBP), handover failure probability, and average waiting time in the queue. Also simulation results are compared to those obtained by: non‐prioritized scheme (FCA), and FCA queuing with FIFO discipline. Results show that our proposed method decreases significantly handover failure probability compared with other two schemes. Copyright © 2009 John Wiley & Sons, Ltd.     

Congested Banyan network analysis using congested-queue states andneighboring-queue effects

A Banyan network analysis technique is presented which more accurately models a congested network than other reported techniques. The analysis is based on the observation that a full queue (within the switching modules making up the network) causes traffic to back up. For a short time after becoming full, the free space in the queue is limited to no more than one slot. A queue in such a condition is called congested. Because of blocking the arrival rate to a congested queue is higher; this tends to maintain congestion. The arrival rate to a congested queue's dual is lower, as is the service rate for queues feeding the congested queue. These effects are captured in the analysis by using a state model that codes the condition of a queue and its neighbors. From a queue's state it can be determined if the queue, its dual, or a next-stage queue to which it connects is congested, as well as the number of items in the queue. Network throughput computed with the model is closer to that obtained from simulations than other Banyan analyses appearing in literature, including those designed to model congestion. Further, the queue-occupancy distributions are much closer than other analyses, suggesting that the analysis better models conditions in congested Banyan networks     

多信道无线通信网混合业务接入控制的离散排队分析

基于无线通信网的运行机制、实时性和非实时性混合业务对无线通信网络不同服务质量(QoS)要求,设计了实时性业务优先接入控制策略,建立了无线通信网络的混合业务带有优先接入控制的多服务台离散时间排队模型Geo1 Geo2/Geo1,Geo2/s,s(PP)。并且应用矩阵几何解方法,对该排队模型进行精确分析,得到了系统的主要性能指标:实时性业务和非实时性业务的平均队长、实时性业务的阻塞概率、系统信道利用率等结果。     

反馈次数服从几何分布的M/G/1排队系统的队长分布

本文从队长过程本身出发,直接研究了具有反馈的M/G/1型排队模型的队长分布,获得了在任意时间t的瞬时队长分布的拉普拉斯变换的递推表达式,以及便于计算的平稳队长分布的递推表达式.值得注意的是本文分析的方法简洁、直观.     

多级门限服务轮询系统MAC离散时间控制协议模型分析

 本文提出了一种新的多级门限服务轮询系统MAC控制协议的分析模型.采用嵌入马尔可夫链理论,对离散时间的多级门限服务轮询系统进行了分析,获得了轮询时刻系统队长的概率母函数,精确解析了系统的平均排队队长、平均循环周期、信息分组的平均等待时延.通过对多级门限服务轮询系统的控制机理研究,分析获得了m控制参数的有效控制取值大小和系统的相关特性.多级门限服务轮询系统综合了基本门限服务轮询系统和完全服务轮询系统,在轮询系统的MAC控制协议的应用方面更为有效.