WDM环形网络保护时间证估与优化分析

本文用逻辑等效方法分析了使用１：１保护配置的ＷＤＭ环行网络的保护倒换规程，并且对需要信令协调的ＷＤＭ环行网络的保护时间进行了分析，得到了保护时间的表达式 在分析各种因素对保护时间影响的基础上，提出了优化的思路。最后还给出了环行网络的保护倒换时序和实例。     

智能电网的PTN线性保护机制研究

智能电网信息化、数字化的发展需求,促使电力通信向IP化的方向发展,使得适合IP业务的分组传送网络技术PTN逐步得到了应用。ITU-T定义的G.8131 PTN线性保护技术可用来保护电网通信业务。为缩短链路故障时N对线性保护同时切换的业务恢复时间,对线性保护实现机制进行研究,提出了倒换操作优先执行的方案。通过理论分析和实验验证,链路故障时N对保护组同时倒换的性能近似O(1),较好的满足了线性保护50ms故障恢复性能,可更好的保障智能电网通信系统的生存性。     

全光网络中攻击定位和恢复算法的研究与仿真

分析了全光网络分布式攻击定位算法,构建了全光网络攻击定位与恢复的仿真平台。实验表明,针对单点攻击,对光网络的透明性引起的"攻击泛滥",能够利用分布式攻击定位算法找到攻击源头,在此基础上,对自动保护倒换和环回两种全光网络进行快速恢复。     

OADM的设计

OADM节点是WDM光网络的关键节点之一。研究了OADM节点的实现方法,提出了一种设计方案,并讨论了光上下路开关阵列的驱动和监控的软硬件制作,完成了下路光功率监测的电路设计以及软件设计。分析了OADM节点保护倒换的原理和节点中的串扰问题。     

在WDM全光网络上构建上层网络的路由算法

在WDM全光网络上构建上层网络需要考虑上层网络的保护机制.上层网络按保护机制可分为最大故障链路数保护网和连通保护网.针对它们的不同特点给出了构建两类上层网络并使费用最低的启发式路由算法.与已有方法相比,具有算法简单,时间复杂性小,容易实用化的特点.大量的模拟计算也证明了算法的正确性.     

一种分布反射型大容量WDM星形单跳网

针对现有分布反射型WDM星形单跳网结构上存在的问题,本文提出了一种新的分布反射型WDM星形单跳网.这种WDM网络不仅抗毁性能好、可靠性高,而且网络容量大、组网灵活性强,可实现网络的在线扩容、升级,为未来大容量WDM局域网提供了一个理想的选择.文章首先论述了该分布反射型大容量WDM星形单跳网的结构,其次分析了网络中各个节点之间的通信,进而计算了网络所支持的最大节点数,最后对全文进行了总结.     

WDM光网络故障的快速共享恢复方案

在网络恢复仿真实验中发现当WDM光网络中的工作通路的链路数目为2或3时, 通路恢复资源能得到较大程度的共享. 在此基础之上, 提出了一种新的WDM光网络故障的恢复方案-分段共享恢复方案(SSR). 与现有的基于通路共享恢复方案(PSR)相比, SSR的恢复时间大大下降, 同时又基本上保持了PSR高效的资源利用率. 阐述了SSR的分段规则和实现过程, 并对SSR的性能进行了理论分析和计算机仿真.     

WDM全光环形网中保护信道的监测方案

本文提出三种关于全光环形网络中保护信道故障的监测方法,即漏光法、额外业务监测法和"辅助波长"监测法,比较分析各自的性能后得出"升级的额外业务故障监测法"是适合任意网络规模且性能优良的一种监测方法.     

一种新型光分插复用器及其在WDM自愈环网中的应用

提出了一种新型的基于FBG和光环形器的双向光分插/复用器结构.它的结构简单,网络配置灵活,而且可实现单纤双向环网中功率放大.结合该OADM,首次给出了在单纤双向DNI环网实现保护的策略,指出此结构在各种WDM网络中实现单纤环网保护的可行性.     

波长重用-扩大基于单纤连接节点的WDM星形单跳网容量

针对可利用的有限信道波长数对基于单纤连接节点的WDM星形单跳网容量限制问题,本文提出了一种有效的解决方案-波长重用.根据该方案,在信道波长数一定的条件下,至少可使网络所支持的节点数-网络容量扩大一倍;在网络节点数不变时,则可大大减少网络节点的排队时延,缓和网络中各通信节点对数据信道波长使用权的竞争矛盾,使网络吞吐量增加1～3倍,有效地改善网络性能.本文首先论述了该基于单纤连接节点的波长重用WDM星形单跳网结构,接着分析了网络的波长重用特性,进而对所要求的光放大器增益和输出功率进行了计算;最后计算了网络的最大节点数和最大信道波长数.     

WDM网络保护容量问题的遗传算法求解

本文以遗传算法为基础,设计了一个与传统数学方法完全不同的遗传搜索寻优算法并提出一种简捷解编码方式,该编码能够极大地简化选择、交叉和变异等遗传算子的执行.仿真实验结果表明文章算法能够迅速地求出保护容量优化问题的全局近似最优解,且能够满足工程设计的要求.     

Survivable routing and spectrum allocation algorithm based on p-cycle protection in elastic optical networks

With the number of large capacity applications in core network increasing, the bandwidth requirement of optical connections in conventional Wavelength Division Multiplexing (WDM) networks keeps enhancing, so that the Orthogonal Frequency Division Multiplexing (OFDM) technology is adopted to provide higher spectrum efficiency and flexibility in the future elastic optical networks. Meanwhile, survivability in the conventional WDM optical networks has been widely studied as an important issue to ensure the service continuity. However, survivability in OFDM-based elastic optical networks is more challenging than that in conventional WDM optical networks because each fiber usually carries even more connections. Therefore, it is necessary to study the new lightpath protection algorithm in elastic optical networks. Since p-cycle protection scheme has short restoration time and simple protection switching procedure, in this paper, we study the static Survivable p-Cycle Routing and Spectrum Allocation (SC-RSA) problem with providing an Integer Linear Programming (ILP) formulation. Since RSA is a NP-hard problem, we propose a new heuristic algorithm called Elastic p-Cycle Protection (ECP) to tolerate the single-fiber link failure. For each demand, ECP scheme can compute highly-efficient p-cycles to provide protection for all of the on-cycle links and the straddling links. We also consider the load balancing and choose the proper working path for each demand. Simulation results show that the proposed ECP scheme achieves better performances than traditional single-line-rate survivable schemes.     

Flexible Twin Open Ring Metro WDM Network

We have demonstrated a flexible twin open ring WDM network for metro applications. A pair of optical switches in the network keeps the fiber rings open to prevent signal circulation. Traffics are broadcast to every node and selected at the receiving side. Superior transmission and protection switching are proved.     

Gain Stabilization in All-Optical Gain-Clamped Cascade of Praseodymium-Doped Fluoride Fiber Amplifiers

The authors present theoretical results of an analysis of an all-optical gain-clamped (AOGC) praseodymium-doped fluoride fiber amplifier (PDFFA) for protecting surviving channels in an amplified wavelength division multiplexed (WDM) network with six cascaded PDFFAs. The theoretical analysis is based on application of a large-signal numerical model that takes into account propagation of pump, signal, and downstream and upstream amplified spontaneous emission and includes time variation effects in a four-level laser system. It is shown that power excursions caused in an eight-channel WDM network by loss addition of six channels could be lower than 1 dB and free of relaxation oscillations if the AOGC PDFFA is strongly inverted and the total loss of the ring resonator is appropriately set.     

Performance evaluation of survivable WDM based SANs in a metro ring network

Storage area networks (SANs) are an essential part of enterprise computing today. There is no comprehensive business continuity plan without SANs in the picture. This paper proposes and evaluates network survivability of optical paths in wavelength division multiplexing (WDM) based storage area networks in a metro ring network. The paper begins with a background on network survivability in metro WDM ring network. Subsequently, the network and node architectures along with their medium access control (MAC) protocols are described. In this work, one link failure (a single cable cut) in metro WDM based SANs in a ring network architecture is considered. Performance evaluation for network survivability in metro WDM SAN is carried out by means of discrete-event computer simulation. Network throughput and packet delay are investigated. The network performance is evaluated for asymmetric (unbalanced) traffic scenarios under Poisson and self-similar traffic.     

波分复用光环形网络结构及性能的研究

本文概述了当前波分复用(WDM)光环形网络结构的物理结构和逻辑结构,并对这些网络结构进行简要的分析,同时对实现WDM光环网络结构中的关键问题进行了简要的探讨。最后对我国发展光环形网络给予一些中肯的建议。     

Survivable WDM-PON with self-protection and in-service fault localization capabilities

In this paper, we analyze the survivability of wavelength division multiplexed (WDM) passive optical network (PON). We propose and experimentally demonstrate a novel survivable WDM-PON architecture with self-protection and in-service fault localization capabilities. Two WDM-PONs are combined together and multiple sub-ring architecture is formed. Protection switching is achieved automatically at optical network units (ONUs) when failure occurs. Fiber loss, fiber fault localization and automatic protection switching in each ONU are real-time monitored in central office (CO) without interrupting customer service. No signaling for failure notice or protection switching is required for either CO or ONUs. Extra fibers required for protection are minimized compared with previous protection schemes. The self-protection and in-service fault localization capabilities of the proposed WDM-PON architecture are experimentally verified.     

Capacity enhancement in packet switched slotted ring wavelength division multiplexed transport networks

In this paper, all-optical WDM networks based on a slotted multichannel ring topology have been investigated. The nodes are equipped with one fixed-wavelength receiver, wavelength-tunable transmitter and provide packet-mode transport in WDM network. The topology provides one logical channel to be associated with each destination node. Each channel is shared in statistical time division by all nodes transmitting to a given destination. The capacity enhancement has been demonstrated by comparing all optical WDM network by increasing the number of nodes. It is concluded that by increasing the number of nodes in the topology, the token queue length capacity, the token arrival rate are increased and the token arrival period is decreased which results in overall increase in the performance and capacity of the logical WDM network.     

多波长复用光传送网的生存结构

本文讨论了光传送网的传送和监控机制,按照传送网通用功能结构的定义,分析了光传送网几种保护交换方式内在的机制,讨论了各自应该属于路径保护还是子网连接保护.在此基础上给出了光信道保护环和光复用段保护环详细的功能结构,同时简要地介绍了这两种保护环信息建模中需要用到的对象类.