A midterm DBA algorithm for quality of service on aggregation layer EPON networks

This work presents a new approach on dynamic bandwidth allocation (DBA) for Ethernet Passive Optical Networks (EPONs). A brief introduction to the DBA area and major term definitions are given. The related research and standardization efforts are presented. Justification that EPONs can be used on the aggregation network is provided, based on their evolution and related research proposals. Focus is given to the Long Reach-Passive Optical Networks (LR-PONs) and their limitations which show the need for a non-polling, midterm DBA scheme for next-generation EPONs. The challenges arising, because of this new approach, are discussed along with possible solutions. Finally, this work proposes the EMDBA algorithm which is able to overcome the discussed issues. The correct operation of this algorithm is confirmed by a set of simulations using OMNet++ framework, and the outcome results show that EMDBA performance is satisfactory in terms of delay and service differentiation.     

一种多业务接入的EPON动态带宽分配算法

EPON以其各方面的优点即将成为接入网的主流技术,但现有的EPON上行链路动态带宽分配算法还有很多不足之处。对结合EPON中的算法对现有的算法进行了改进,提高了带宽利用率和时延抖动。在对MAC进行描述的基础上进行了EPON系统仿真模型,结果表明：改进后的算法具有较高的带宽利用率和较EF业务时延抖动,与此同时,也明显降低了AF、BE业务的队列时延抖动。     

EPON上行信道中的动态带宽分配算法研究

传统的EPON系统的上行动态带宽分配方案是类似于IPACT的基于时隙长度分配的,这样虽然使上行信道得到了充分的利用,但是由于包延迟变化较大,不适合实时业务的传送.文章提出了一种多级授权分离发送动态带宽分配算法,它可以为不同业务提供不同的服务质量,既满足了实时业务的需要,又在一定程度上提升了网络的利用率.通过仿真测试,发现这种算法均有良好的时延特性和较稳定的队列尺度,能较好地支持多业务优先级的EPON系统.     

EPON中一种改进的动态带宽分配算法的设计

动态带宽分配是EPON系统的关键技术之一.文章首先分析了一种基于IPACT的RR算法的,然后提出一种有效的动态带宽分配算法MLQF.仿真试验表明,当网络负载很大时,MLQF算法在平均包延时和平均队列长度方面的性能均要优于已有的RR算法.     

EPON中的一种新型动态带宽分配算法

动态带宽分配是以太网无源光网络(EPON)系统中的一个重要研究领域,提出了一种基于业务的两层三次带宽分配的DBA新型算法.该算法在兼顾动态带宽分配的带宽利用率和QOS保证方面进行了改进,通过研究分析给出了最优算法,并在模拟流量下进行了性能分析.通过与已有算法的对比,证明其有很好的性能.     

Adaptive polling algorithm to provide subscriber and service differentiation in a Long-Reach EPON

A novel interleaved polling algorithm for Long-Reach EPONs is proposed in order to simultaneously provide subscriber and class of service differentiation. It is demonstrated that the new polling algorithm applied to a typical 100 km Long-Reach EPON performs better than centralized methods, where bandwidth prediction is needed to overcome the higher round trip time in which ONUs cannot transmit. As polling methods in Long-Reach EPONs do not require prediction, they are much simpler and show less computational complexity than centralized schemes, avoiding the inaccuracy of bandwidth prediction. Simulation results show that the new algorithm increases the achieved throughput when compared to centralized algorithms with traffic prediction, obtaining a significant reduction of both mean packet delay and packet loss ratio for the highest priority service level profiles.     

EPON系统多业务承载调度机制的研究

本文根据当前宽带多业务的需求,分析了EPON系统承载多业务的必要性,提出了衡量EPON系统调度机制优劣的因素.在介绍了两种现有调度机制工作原理的同时,根据各方面因素对这两种调度机制的优劣进行了分析,最后给出了EPON系统中这两种调度机制目前适用的网络场景.     

一种公平的EPON动态带宽分配算法

提出一种EPON上行链路动态带宽分配算法一周期比例DBA。ONU基于多门限周期地上报带宽请求，OLT根据ONU的带宽请求及其合约带宽进行动态带宽分配。当多个ONU竞争系统带宽时，OLT按照ONU合约带宽的比例进行带宽分配。仿真结果表明：周期比例DBA算法在实现高带宽利用率的同时又具有良好的公平性。     

一类基于网络服务品质要求的单播路由算法

本文提出了一类基于网络服务品质QoS（quality of service）要求的单播路由算法。首先,我们给出了基于网络分组调度机制WFQ的延迟和带宽相耦合的分析模型,从而推导出了最佳端到端通信延迟的上界。基于该模型,我们改造了传统最小跳数和最短延迟的两类路由算法以支持实时通信的服务品质要求。此外,我们还给出了两种新的服务品质路由算法,它们是多路径第k条最短延迟路由算法以及组合带宽和跳数（hop counts）的最大能量路由算法。仿真实验结果表明,四种算法尤其是后两种算法在满足用户带宽、延迟服务要求以及增加网络资源使用效率和网络吞吐率等方面各有特色。     

A programmable optical network testbed in support of C-RAN: a reliability study

With both mobile network services and related data traffic volume on the rise, reliability of the radio access network is of the essence. A number of radio functional splits are defined by 3GPP to offer increased flexibility of implementation and feasibility of new mobile network services. For example, it is possible to implement certain radio functions in the Cloud, an architectural solution referred to as C-RAN. C-RAN solutions require highly reliable backhaul and fronthaul network designs. This paper describes PROnet, a programmable optical software-defined network testbed, which has been upgraded to offer backhaul and fronthaul transport capabilities in support of C-RAN functionalities with increased reliability. The testbed is upgraded with a specially designed 1 + 1 protection mechanism at the Ethernet layer in order to meet the stringent network round-trip requirements imposed by one of the C-RAN functional split options on the fronthaul.

     

Packet Delay Analysis of Symmetric Gated Polling System for DBA Scheme in an EPON

In this paper, we analyze the mean packet delay of a dynamic bandwidth allocation (DBA) scheme in an Ethernet passive optical network (EPON). We propose the interleaved polling system with a gated service discipline and a two-stage queue in order to investigate the delay performance of DBA scheme in an EPON. We assume that input packets arrive at an optical network unit (ONU) according to a Poisson process from several types of users. We use a continuous time queueing model in order to find the mean packet delay and the mean cycle time of an arbitrary packet. We obtain the closed form solution for the mean packet delay of the proposed gated polling system with a two-stage queue. We obtain another result on the mean packet delay by solving a system of linear equations derived from the moments of the queue length distribution. We give some numerical results to investigate the delay performances for the symmetric polling system with statistically identical stations. In addition, we compare numerical results on the closed form solution with numerical results on a system of linear equations.     

支持多业务预测机制的EPON动态带宽分配算法

针对IPACT算法中存在较严重的轻载惩罚现象,提出了一种支持多业务预测机制的动态带宽分配算法(eIPACT算法).通过估计两个连续轮询之间的不同业务分组的到达量,并给ONU授权额外的带宽,减少了ONU分组中的等待时间和缓存占用.采用多业务优先级调度策略,不仅能避免轻载惩罚还可以保证系统的服务质量.结果表明,该算法既极大...     

UMTS核心网服务质量保证算法研究

UMTS系统——第三代移动通信系统的标准之一．其重要特征是支持多种多样具有不同QoS要求的业务。同时．随着Internet的飞速发展．UMTS已经把IP作为其核心网数据域的协议。然而由于IP尽力而为的特性如何确保对服务质量要求很高的业务性能成为一个急需解决的问题。本文把Differ机制应用于基于IP协议的UMTS核心网数据域，并在此基础上着重研究实现了经典包调度算法虚拟时钟VirtualCLock。此算法根据进入UMTS核心网的不同包的QoS类别进行分类排队．在交换节点上进行拥塞控制。通过仿真与WFQ算法进行比较，可以明显看出VirtualCiock调度算法优越性之所在。     

基于多业务预测的EPON动态带宽分配算法

针对EPON系统中上行链路的时分复用机制,提出了一种支持流量预测与预分机制的动态带宽分配算法(PEM-DBA).该算法能够对高优先级业务进行流量预测,并根据预测结果预先分配带宽.仿真结果表明,该算法能在保障高优先级业务优的同时,降低数据时延,提高带宽的利用率.     

基于多业务预测的EPON动态带宽分配算法

针对EPON系统中上行链路的时分复用机制,提出了一种基于多业务预测的动态带宽分配算法.该算法根据各个优先级业务的实时变化,通过一定的预测机制,实现动态分配带宽.相对其它算法,该算法能在保障高优先级业务优先的同时,降低数据时延.     

A sequential algorithm for the universal coding of finite memorysources

The estimation and universal compression of discrete sources are considered, and a sequential algorithm for the universal coding of finite memory sources, attaining asymptotically minimum redundancy, is presented. The algorithm performs an online estimation of the source states and uses an arithmetic code     

A telecommunications quality study using the analytic hierarchyprocess

An analytic hierarchy process (AHP) approach that can be used either for the analysis and comparison of the quality of several telecommunications companies, or for the evaluation of alternate technologies in telecommunications is presented. The method is based on pairwise comparison between several factors that affect the quality of service in a hierarchical structure. Two particular formulations are presented and discussed extensively     

CSMA/CD用作EPON上行接入控制方案的研究

由于以太网成熟的技术和广泛的应用,EPON(以太网无源光网络)接入技术已经成为光接入网技术中的最新发展趋势。用N×N无源星型耦合器来取代1×N无源星型耦合器,通过在无源星形耦合器处添加光环回机制,摆脱了距离的限制,成功地将传统的CSMA/CD(载波侦听多路存取/冲突检测)协议用于EPON的上行接入控制。     

A new algorithm for optimization of quality of service in peer to peer wireless mesh networks

Wireless Networks - Nowadays, wireless mesh networks are known as important parts of different commercial, scientific, and industrial processes. Their prevalence increases day-by-day and the future...     

A shared service algorithm for a trunked mobile system

A model has been developed and solved which captures the essence of the concept of mobile dispatch service. There are two types of users, dispatch and interconnect (calls routed from the public switched telephone network, of much longer holding times). Also, only some of the available repeaters can be used for interconnect traffic, and blocked interconnect calls are cleared. Dispatch calls, however, can access all repeaters, and then are queued if all repeaters are busy. One design decision involves a trade between blocking of interconnect calls and queueing of dispatch calls. A formula has been derived for both interconnect blocking probability and the mean dispatch queueing time to permit this trade. The results indicate that a good operating point is to have (N - ad)(rounded down) interconnected repeaters, where there are N total repeaters and adErlangs of dispatch traffic.