基于光突发交换QoS的负载动态平衡法

提出了一种基于自适应交替路由的负载平衡方法,来缓解通信链路上的拥堵问题,从而减少基于WDM光突发交换(OBS)网络中的丢包率,提高服务质量。并通过基于丢包率的仿真实验结果,证明负载动态平衡算法在提高QoS方面优于传统的最短路径算法。     

OBS网络中改进的ODBR算法

信道调度算法是提高光突发交换(OBS)网络性能的关键技术之一.结合ODBR重调度算法和FDL的延迟作用,提出来一种Improved-OBDR算法.仿真结果表明改进算法在保证高优先级低丢包率的同时,保证低优先级尽可能低的丢包率,提高了资源利用率.     

光突发交换网络中基于波长分集的QoS算法

光突发交换(Optical Burst Switching, OBS)被公认为是构建下一代光网络的有效交换技术。在OBS网络中有效地支持QoS (Quality of Service)是一个很重要的问题。该文从波长分集的思想出发,提出了几种适合OBS的QoS算法。这些算法可以根据各个优先级业务的变化情况,动态地调整各个优先级的业务使用的波长数目。通过仿真,并和已有算法相比,说明所提出的算法可以更好地提供区分服务,同时有效提高信道的利用率,降低整体的丢失率。     

无线MESH网络QoS机制研究*

随着无线MESH网络与实时多媒体业务的迅速发展,要求无线网络不仅能提供简单的连通性,还需要提供非常有效的QoS保证机制。针对这一需求,提出一种基于服务流映射的QoS保障机制,通过服务流定义及业务映射、基于QoS优先级的带宽预约、分级多轮调度等关键算法,实现多业务QoS保障。并通过仿真和样机测试验证QoS性能。仿真及试验结果分析表明,与无QoS机制相比,时延降低约20%,在各种链路负载下,高优先级业务丢包率维持在0.05%左右,能够很好的满足无线MESH网络多业务QoS需求。     

两种新型的OBS网络数据信道调度算法

光突发交换(OBS)是实现IP/DWDM网络的一种极有前途的方案。该文提出了两种新型的OBS网络数据信道调度算法:最少波长转换(MWCT)调度算法和区分服务(SD)调度算法。通过仿真,证明了这两种算法在减少OBS网络中的光信号的波长转换和保证高优先级数据可靠传输方面比已有的FF和LAUC调度算法具有更好的性能。     

光突发交换网络的QoS策略研究

光突发交换网络(OBS)是一种IP over WDM的光交换技术,能很好地支持突发业务。OBS系统采用单向波长资源预留方式为突发数据分组预留前向数据波长通道,这样提高了传输交换效率、减少了建链时间,但同时因路由连接的非确定性而引起突发分组的易丢失性。所以QoS戍为OBS网络中的最亟需解决的问题。对OBS网络所采取的多种改善其QoS的策略进行了研究。     

混合光突发交换网络的研究

提出了一种新的混合光突发交换（HOBS）网络，并且使用环网对网络进行了仿真比较研究。仿真结果表明HOBS的丢包率远低于OBS，并且下降的程度决定于拆分比例、缓存的大小以及节点的处理速率等参数。     

OBS网络中的主动拥塞控制策略研究及性能分析

根据光突发交换(Optical Burst Switching--OBS)网络的结构和特点,分析了其核心节点在数据信道调度发生拥塞时拥塞控制策略的缺陷,提出了OBS网络中一种主动拥塞控制策略(ACC),详细讨论了该策略的具体实现过程.通过仿真验证,在OBS网络中采用该算法能减少突发数据包的丢包率,从而达到改善整个OBS网络性能的目的.     

自适应RED算法在OBS网络中的应用

队列管理是光突发交换(OBS)网络边缘节点的重要功能之一.对随机早期检测(RED)队列管理算法及两种自适应RED算法在OBS网络中的应用进行了研究和仿真分析.仿真结果表示:动态调整队列权重的自适应RED算法和动态调整最大丢包率的自适应RED算法均能改进RED算法的性能,但是后者的性能优于前者.     

光突发交换网络中服务质量保证机制的研究

如何在光突发交换(OBS)网络中为承载的业务提供服务质量(QoS)保证,已经成为当前OBS领域的一个研究热点.从算法思想、QoS保证性能等方面,对当前几种主要的服务质量保证机制进行了研究:基于偏置时间的QoS机制、分段型QoS机制、比例型QoS机制、抢占式QoS机制、IP DiffServ over OBS的QoS机制以及基于数据信道分组的QoS机制.探讨了在设计一个有效的QoS保证机制时应考虑的因素以及今后的研究方向.     

光突发交换网络基于优先级与突发包分割的光缓存方法

为了保证光突发交换(OBS)网络中不同优先级业务的服务质量(Qos)和有效地降低突发包的丢失率,提出了一种基于优先级与突发包分割的光缓存方法.该方法通过在输出数据信道上设置光纤延迟线组来缓存被分割的冲突突发包.当冲突发生时,基于突发包的优先级进行"竞争突发包头部分割或者原突发包尾部分割,,处理;无冲突部分进行交换或者直...     

OBS网络中基于优先级的先分割后缓存冲突解决方法

为了有效地降低突发包的丢失率和保证OBS网络中不同优先级业务的服务质量,提出了一种基于优先级的先分割后缓存冲突解决方法。该方法通过在多波长信道系统的输出数据信道上设置光纤延迟线组来缓存被分割的冲突突发包。当冲突发生时,首先基于突发包的优先级和处理完毕时间进行"竞争突发包头部分割或者原突发包尾部分割"处理;无冲突部分进行交换或者直接在事先预留的输出数据信道上处理,冲突部分的分割突发包进行光缓存。仿真结果表明,多波长信道系统中,高优先级突发包的丢失率低于低优先级突发包的丢失率。同时该方法在一定程度上可以有效地减少端到端的传输时延和整个网络的丢包率,从而提高整个OBS网络的性能。     

Burst scheduling for differentiated services in optical burst switching WDM networks

Optical burst switching (OBS) is one of the most important switching technologies for future optical wavelength division multiplexing (WDM) networks and the Internet. The model of differentiated services has been proposed to support quality of service (QoS) in the IP‐based Internet. It is also very important to have differentiated service support in OBS networks. When the burst scheduling in an OBS network is set up appropriately, network can support differentiated services. In this paper, we proposed a new burst scheduling scheme, called differentiated scheduling with identical priority offset time (DSIPO). In DSIPO, the same priority offset time is used for all the bursts destined to the same edge node regardless of their priorities. Differentiated services in terms of burst loss probability are achieved by processing the control packets of higher priority class bursts, thus reserving resources for their data bursts, more promptly upon their arrival than those of lower priority class bursts. Each intermediate (core) node can adjust the burst loss probabilities of various burst classes by choosing its own differentiated processing delay value for each priority class or its own differentiated processing delay difference value between any pair of adjacent priority classes. We model and analyse DSIPO in terms of the burst loss probability for each priority class with simulation validation. The performance of DISPO is evaluated by simulation. Copyright © 2004 John Wiley & Sons, Ltd.     

A Novel Optical Burst Assembly Technique Based on a Dynamic Threshold Mechanism to Support Scalable QoS

In IP networks, coarse packet classification is a scalable QoS solution. Similarly, it can also be utilized to an OBS network. In order to match IP QoS requirements with the data processing capacity and flexibility of OBS networks, we propose a novel optical burst assembly technique, which is based on mapping rules and a dynamic threshold mechanism called ATQ-DT. How to map the IP QoS to burst priority is resolved by the mapping rules, and how to efficiently allocate the assembly capacity among classes belonging to the same priority is answered by ATQ-DT. This mechanism determines the maximum share for each class, which is proportional to the current unused capacity. Among the three mapping rules we propose, TQ-MAP is the most reasonable one because it considers both the traffic condition and the QoS requirement. As shown by simulation results, the assembly technique ATQ-DT with TQ-MAP can most remarkably improve the packets loss probability (PLP) to support QoS.     

OBS考虑优先级的突发包碎片可控合并重传算法

为了降低光突发交换网络中突发包的丢失率、降低网络路径的阻塞率、减小突发包冲突的概率,提出了考虑优先级的突发包碎片可控合并重传算法。当网络中数据通信发生冲突时,该算法能根据优先级进行突发包的分片,核心节点将这一信息反馈给边缘节点,边缘节点根据突发碎片的优先级以一定的概率重传被丢弃的突发包分片;同时,针对由于多次重传导致的突发包碎片过多的问题,该算法还按照突发包碎片的优先级顺序进行碎片重组,大大降低了网络的阻塞率。结果表明,相比以往的冲突解决算法,此算法在网络业务繁忙时的数据丢比特率和网络阻塞率方面的改善作用有比较明显的优势。这一结果对光突发交换网络的网络的性能改善方面是有帮助的。     

OBS基于回退和信道分级的冲突解决算法

解决突发包的冲突问题是光突发交换网络的关键技术之一。为了降低突发包冲突时丢包率,提出了一种新型的基于信道分级和回退机制的冲突解决算法,该算法考虑突发业务优先级,将信道分成两个级别,有区别地对待高低优先级两种业务类型,并且增加了一部分回退信道作为保护和重发冲突数据包,能够有效地保证高优先级业务的传输可靠性。结果表明,当冲突发生时,网络能根据此时高低优先级业务量的比重配比,自适应地调节两个级别信道的数量,兼顾到低优先级业务的低丢包率,保证了较低的延时率。此算法相比以往的冲突解决算法具有较低的丢包率和相对小的延时率。     

基于BD技术的光突发竞争解决方案

将BD法结合波长资源预留算法提出一种新的突发竞争解决方案。该方案通过在突发竞争时牺牲低优先级突发的传输完整性,以保证高优先级的业务的丢失率,同时降低了传输时延。最后对基于BD法的突发竞争解决方案进行了网络仿真,并和传统的传统基于额外偏置时间(JET)的方案比较,结果表明在平均数据丢失率相当的前提下,改进的BD法能有效的降低突发包的端对端时延。     

Improved ant colony-based multi-constrained QoS energy-saving routing and throughput optimization in wireless Ad-hoc networks简

In order to establish a route supporting multi-constrained quality of service（QoS）, increase network throughput and reduce network energy consumption, an improved ant colony-based multi-constrained QoS energy-saving routing algorithm（IAMQER） is proposed. The ant colony algorithm, as one of the available heuristic algorithms, is used to find the optimal route from source node to destination node. The proposed IAMQER algorithm, which is based on the analysis of local node information such as node queue length, node forwarding number of data packets and node residual energy, balances the relationship between the network throughput and the energy consumption, thus improving the performance of network in multi-constrained QoS routing. Simulation results show that this IAMQER algorithm can find the QoS route that reduce average energy consumption and improves network packet delivery ratio under the end-to-end delay and packet loss ratio constraints.     

OBS网络中一种基于突发包优先级分割的可控重传方案

在光突发交换(OBS)网络中,突发包会由于竞争OBS核心节点输出端口的有限波长资源而发生冲突。突发包重传能够在一定程度上减少由于突发包在核心节点冲突而导致的数据损失,但重传次数的增加可能会加重网络负荷,反而增加数据丢失率。并且,在多业务存在的OBS网络中,重传方案需要能够实现区分服务以保证网络的服务质量(QoS)。据此,本文提出一种基于突发包优先级分割的可控重传方案,在实施优先级分割的同时,根据网络负荷赋予每次重传不同的概率,并对重传次数加以控制。最后,仿真分析了路径阻塞率和不同优先级业务的字节丢失率(ByLP,byte loss probability)性能。     

A new composite assembly mechanism for supporting QoS in OBS networks

To provide the differential quality of service（QoS）for different classes of packets and reduce the packet loss probabil ity（PLP）,a novel priority-based composite assembly scheme for optical burst switching（OBS）networks is proposed The low and high packet classes are aggregated into a single burst simultaneously,and the highest-priority packets ar placed in the middle,while the low-priority packets are at the tail and head of the burst.The priority is lowered gradu ally from the middle to the ends.Simulation results demonstrate that the proposed assembly strategy not only guaran tees the integrity of the high-priority bursts,but also significantly reduces the average end-to-end delay of the burst and the PLP of network.So it can adapt to the flexible network with QoS requirement.