EPON中一种改进的DBA算法

动态带宽分配是EPON系统的关键技术之一。由于多个ONU共享同一上行信道,对上行数据流的控制显得尤为重要。EPON系统使用请求/应答机制对ONU进行带宽分配。在ETRI算法的基础上,提出了一种改进的算法,它支持队列优先级和ONU之间的公平性。通过仿真结果可以看出,改进的算法与ETRI相比,大大减少了平均队列长度。     

基于带宽借贷的EPON动态带宽分配算法

针对以往以太网无源光网络(EPON)动态带宽算法中存在的带宽分配不公平性问题,提出了基于带宽借贷机制的动态带宽算法LLR和LWR,其基本思想为当某光网络单元(ONU)有空余带宽时,光线路终端(OLT)将此ONU多余带宽借贷给重负载ONU,当债权ONU遇到带宽不足的情况时,OLT将会安排负债ONU偿还其未满足请求部分带宽.通过在正常使用和存在"贪婪"用户的两种情况下的仿真,分析了这两种算法的平均时延和丢包率特性.仿真结果表明这两种算法能为正常使用用户提供有保障的公平性服务,消除了以往算法在若干用户过量使用的情况下所有用户都受影响的问题,使动态带宽分配更加公平.     

应用业务预测的动态带宽分配算法

当前以太无源光网络中动态带宽分配算法主要是基于轮询机制.其中限制带宽分配算法根据各个ONU发送的队列长度能够动态分配带宽,但是这种算法不能实时获得各个ONU的队列长度.因此,利用维纳滤波的方法对自相似业务流量进行预测,预测的结果应用于限制动态带宽分配,得出一种改进的动态带宽分配算法.这种改进算法通过预测ONU的队列长度,更确切地反映了其状态信息,有利于OLT进行准确地带宽分配.对这种算法进行了仿真分析,在业务负载介于0.1～0.5的情况下,平均包时延比较接近0.1ms,达到了改进目的.     

一种轮询周期受限的EPON双级动态带宽分配算法

提出一种新的EPON上行带宽分配算法——轮询周期受限的双级动态带宽分配算法。这种算法结合用户等级协定和DiffServ的特点,采用周期受限的轮询方法和双级的带宽分配方式,在OLT端根据ONUi提供的业务队列情况对业务量进行估算,并授权带宽给ONUi,ONUi根据实际的业务量进行再分配。仿真结果表明,这种算法实现了高的带宽利用率,与DBAM相比有效地提高了EPON的QoS。     

以太无源光网络单级多功能ONU内调度算法

针对以太无源光网络(EPON),为各类业务提供服务质量支持,特别是保障时延敏感型业务的服务质量,提出一种调度算法,应用到EPON的光网络单元(ONU)中.我们设法让这个单级调度算法具备多级调度功能.通过理论分析和仿真测试,证明本算法具有灵活的优先级机制和公平调度功能.     

E EPON在实际应用中的研究

随着互联网的广泛应用,人们对互联网带宽、稳定性要求越来越高.EPON技术已经成为当前各运营商实行用户接入的主要形式.本文主要针对EPON的定义、接入方式等进行了简单的探讨.     

M小区EPON网络割接技术探析

EPON通信系统由光纤线路终端(OLT)、光分配网络(ODN)和光网络单元(ONU)组成。EPON组网采用树形拓扑结构,光信号通过分光器把OLT一根光纤下行的信号分成多路给每一个ONU,每个ONU上行的信号通过分光器合成在一根光纤里给OLT。     

基于RFM分析模型的结构动态特性模糊优化算法研究及应用

本文基于回归预报统计分析模型(RFM)与多元多项式的特点和性质,对结构优化目标参数引入模糊因素,提出了一个结构动态特性模糊优化算法.该算法从理论上给出了结构目标参数模糊优化的数学准则并给予了证明.本文定量地研究了某钢桁架结构模态参数与边界连接参数之间的关系并利用该算法对该钢桁架结构的模态参数进行模糊优化.通过数值计算,...     

EPON上行链路动态带宽分配算法(DBA)分析

介绍和分析EPON的特点,侧重分析动态带宽分配算法的原理和相应类别的优缺点。主要分析3种DBA算法——间插轮询(IPACT)带宽分配算法算法、BGP算法和基于比例分配的支持服务等级区分带宽分配算法,分析其原理、上行通道的利用率及对不同业务等级之间公平性的影响,得出各自优缺点的结论。     

EPON网络技术的研究与应用

EPON网络是采用FTTB方式组建网络,其组网基本单元为OLT和ONU。OLT为局端设备提供丰富的PON口,用于连接ONU设备;ONU是用户端设备提供相应的数据和语音接口,实现用户业务的接入。对于不同业务的接入实现主要是采用对不同用户不同业务打不同的VLAN标签来透明传输到相应的业务接入服务器,并将相应的VLAN标签剥离后送入IP承载网传输。     

10G EPON的研究

本文探讨了万兆以太网无源光网络（10G EPON）的不同实现方法：上行分别基于时分多址或者波分多址,对上行采用波分多址（WDMA）接入的实现方法进行了更为详细的研究。分析了万兆以太网无源光网络存在的问题,最后讨论了其应用方向。     

EPON上行接入动态带宽分配算法的研究

以太无源光网络的上行方向需要一种多址接入技术来防止以太数据包的碰撞。时分多址技术应用广泛,而波分多址技术极具潜力,是发展的方向。基于时分多址技术,提出了一种改进的动态带宽分配算法,结合了轮询机制和申请的优先级。通过建模仿真,证明了该算法可以取得较小的平均包延时和较高的带宽利用率。     

TWDM-PON-AN optical backhaul solution for hybrid optical wireless networks

Abstract

To improve the performance of broadband access networks Full Service Access Network selected Time and wavelength division multiplexed Passive Optical Network (TWDM-PON) as the primary solution for next-generation optical access (Next-Generation Passive Optical Networks 2 (NGPON2)). This paper reviews the recent progress in this access technology. Different possible solutions for the-next generation access are explained. Comparison of the different TWDM architectures experimentally demonstrated so far is made considering the large split, long reach and high capacity requirements of NGPON2. Major technical challenges in implementing the TWDM networks are discussed. Possible options for designing hybrid wireless–wireline architectures are explained taking care of the high bandwidth provided by the optical networks and high mobility of wireless networks. Also an integrated optical wireless architecture is suggested using TWDM-PON as an optical backhaul.     

Data-mining-based dynamic dispatching rule selection mechanism for shop floor control systems using a support vector machine approach

The purpose of this paper is to develop a data-mining-based dynamic dispatching rule selection mechanism for a shop floor control system to make real-time scheduling decisions. In data mining processes, data transformations (including data normalisation and feature selection) and data mining algorithms greatly influence the predictive accuracy of data mining tasks. Here, the z-scores data normalisation mechanism and genetic-algorithm-based feature selection mechanism are used for data transformation tasks, then support vector machines (SVMs) is applied for the dynamic dispatching rule selection classifier. The simulation experiments demonstrate that the proposed data-mining-based approach is more generalisable than approaches that do not employ a data-mining-based approach, in terms of accurately assigning the best dispatching strategy for the next scheduling period. Moreover, the proposed SVM classifier using the data-mining-based approach yields a better system performance than obtained with a classical SVM-based dynamic dispatching rule selection mechanism and heuristic individual dispatching rules under various performance criteria over a long period.     

Bandwidth allocation in Diffserv-enabled ethernet passive optical networks

Ethernet passive optical networks (EPONs) have attracted considerable attention from the industry, as they offer a simple, highly flexible and cost-effective solution to the problem of providing broadband access to a customer. The authors present a new approach to bandwidth allocation in EPONs where the optical line terminator (OLT) has full control over the access mechanism. This results in much simpler optical network unit (ONU) architecture. It is shown that such an OLT-centric architecture offers full support for differentiated services and makes enforcement of service level agreements possible. Extensive simulation experiments show that bandwidth allocation algorithms deployed in such a centralised environment can deliver good performance in terms of average and maximum packet delay. The authors introduce two new algorithms that target SLA-aware EPONs and provide a good protection of offered quality of service against interference from other sources.     

A particle swarm optimizer for constrained multi-objective engineering design problems

This article presents a particle swarm optimizer (PSO) capable of handling constrained multi-objective optimization problems. The latter occur frequently in engineering design, especially when cost and performance are simultaneously optimized. The proposed algorithm combines the swarm intelligence fundamentals with elements from bio-inspired algorithms. A distinctive feature of the algorithm is the utilization of an arithmetic recombination operator, which allows interaction between non-dominated particles. Furthermore, there is no utilization of an external archive to store optimal solutions. The PSO algorithm is applied to multi-objective optimization benchmark problems and also to constrained multi-objective engineering design problems. The algorithmic effectiveness is demonstrated through comparisons of the PSO results with those obtained from other evolutionary optimization algorithms. The proposed particle swarm optimizer was able to perform in a very satisfactory manner in problems with multiple constraints and/or high dimensionality. Promising results were also obtained for a multi-objective engineering design problem with mixed variables.     

光分插复用器的设计原则与功能实现

光分插复用器(OADM)是光传送网中的重要网元。本文提出了一种OADM的设计原则与实现方法，讨论了实现OADM中的状态检测、功率均衡、自动保护倒换等关键技术问题及相应的解决方法，并给出了利用OADM进行长距离传输与组网的实验研究结果。结果表明，我们研制成功的OADM具有先进性、实用性和可靠性，现已成功地应用于中国高速信息示范网(CAINONet)中。     

Improved customer satisfaction with a hybrid dispatching rule in semiconductor back-end factories

On-time delivery is a vital factor for customer satisfaction in the competitive semiconductor manufacturing industry, and to optimize on-time delivery manufacturers must continuously improve their management of work-in-progress (WIP). However, in undertaking to optimize WIP, managers are also concerned with short cycle times, high throughput, and high utilization. In an attempt to find the most satisfactory solution to these potentially conflicting requirements with regard to WIP, the present study employs fuzzy analytic hierarchy process (AHP) to determine an appropriate set of acceptable WIP deviation levels (AWDLs). These AWDLs are then used in a proposed hybrid dispatching rule to determine the operational priorities of jobs. A simulation model using real-world data is then constructed to examine the proposed mechanism for improving customer satisfaction. The findings of the study confirm that the proposed mechanism is capable of simultaneous consideration of various goals and the achievement of enhanced performances with respect to due-date delivery from semiconductor back-end processes.