A resilient star-ring optical broadcast-and-select network with a centralized multi-carrier light source

This article presents a resilient star-ring optical broadcast-and-select network with a centralized multi-carrier light source (C-MCLS). It consists of a star part network and a ring part network. Optical carriers generated by the C-MCLS are broadcast to all network nodes, which select and utilize them for data transmission. Optical carrier distribution as well as data transmission and receiving are performed in the star part network. The ring part network is for fiber failure recovery. The network resilience property enables the design of a fast distributed failure recovery scheme to deal with single and multiple fiber failures. We introduce a fiber connection automatic protection switching (FC-APS) architecture that only consists of optical couplers and 1 × 2 optical switches for each network node. Based on the FC-APS architecture, we design a distributed failure recovery scheme to recover the carriers and data affected by fiber failures. The fiber failure detection and failure recovery operations are performed by each network node independently only using its local information. We evaluate the recovery time of the distributed failure recovery scheme compared with that of the centralized one. Numerical results show that the distributed scheme greatly reduces the recovery time compared to the centralized configuration in the recoveries of both single and multiple fiber failures. Optical power loss analysis and compensation of the recovery routes in the distributed scheme are also presented. We show the required number of optical amplifiers for the longest recovery route in the distributed scheme under different numbers of network nodes and fiber span lengths.     

Transparent ultra-long-haul DWDM networks with "broadcast-and-select" OADM/OXC architecture

We describe an experimental realization of ultra-long-haul (ULH) networks with dynamically reconfigurable transparent optical add-drop multiplexers (OADMs) and optical cross-connects (OXCs). A simple new approach to dispersion management in ULH dense-wavelength-division-multiplexing (DWDM) transparent optical networks is proposed and implemented, which enables excellent transmission performance while avoiding dispersion compensation on a connection-by-connection basis. We demonstrate "broadcast-and-select" node architectures that take full advantage of this method. Our implementation of signal leveling ensures minimum variations of path-averaged power among the wavelength-division-multiplexing (WDM) channels between the dynamic gain-equalizing nodes and results in uniform nonlinear and spontaneous-emission penalties across the WDM spectrum. We achieve 80/spl times/10.7-Gb/s DWDM networking over 4160 km (52 spans/spl times/80 km each) of all-Raman-amplified symmetric dispersion-managed fiber and 13 concatenated OADMs or 320/spl times/320 wavelength-port OXCs with 320-km node spacing. The WDM channels use 50-GHz grid in C band and the simple nonreturn-to-zero (NRZ) modulation format. The measured Q values exhibit more than a 1.8-dB margin over the forward-error correction threshold for 10/sup -15/ bit-error-rate operation. We compare these results with point-to-point transmission of 80/spl times/10-Gb/s NRZ WDM signals over 4160 km without OADM/OXC and provide detailed characterization of penalties due to optical signal-to-noise-ratio degradation, filter concatenation, and crosstalk.     

基于OADM的城域光网络节点结构

使用光滤波器件或光开关就可构成具有重构性的光分插复用经能使ＷＤＭ系统更加灵活地与其它节点形成连接入网为执行联风和业务复接功能。ＯＡＤＭ和ＤＷＤＭ技术的结合构成了最的城域光网络解决方案,本文从描述全光通信网络节点功能结构出发,研究了以ＯＡＤＭ技术的为基础的城域光网络节点结构。     

Performance evaluation of large capacity broadcast-and-select optical crossconnects

In this work, two bufferless high capacity broadcast-and-select optical switching node architectures are presented and their performance is evaluated. The architectures are modular permitting the expansion from basic to complex structures by adding new blocks/components in a gradual way, enhancing at the same time the corresponding network functionality. The blocking performance is assessed and scheduling algorithms are proposed to solve contention for a single node. Finally, physical layer modeling is carried out in order to investigate node scalability and node cascadeability. Overall, the proposed solutions are offering modularity, transparency to switching technology, graceful evolution and high performance at an affordable cost.     

Power series-based algorithm for dedicated protection in WDM optical networks

WDM optical networks allow the transmission of multiple services with high rates and low cost. Therefore, the occurrence of a failure in any network element can cause loss of several services. Some survival mechanisms may be used to try to overcome this type of failure event. We present in this paper a new dedicated protection algorithm for link-failure survivability in WDM optical networks, referred to as power series routing-based dedicated protection (PSR-DP) algorithm. PSR-DP is based on the evaluation of the network links’ costs by using a power series expansion. This power series expansion uses input variables based on some relevant information of the network such as link physical length and wavelength availability. Other contribution of this paper is to propose a new input variable based on the wavelength continuity constraint. The performance of the proposed algorithm is compared to other well-known algorithms in the literature. We also propose a modification to Suurballe’s algorithm and compare it with our PSR-DP algorithm. Three different topologies are used in our simulations, and statistical analysis is performed on the results of the investigated algorithms. In all simulated cases, PSR-DP algorithm outperformed the other analyzed algorithms.     

WDM网络中低开销的动态1＋N专有分段保护策略

针对现有波分复用（WDM）网络保护机制倒换时间长、资源消耗较大的问题,提出了一种低开销的动态1＋N专有分段保护（DSDP）策略,能够根据当前网络资源耗费情况动态地确定需要保护的网元,采用线性编码方法,利用单个工作路径对多个工作路径进行专有保护。仿真验证表明,本文策略能极大地降低用于保护的网络资源消耗,同时能有效地利用光...     

WDM光网络中一种优先共享通路保护算法

为了提高波分复用光网络的可靠性,常采用分段共享通路保护算法,该方法通常要求保护通路要均匀分段并且应满足共享风险链路组约束,网络业务的阻塞率也就比较高,因此提出了用优先共享通路保护算法来降低业务阻塞率。通过计算机仿真进行了理论分析和实验验证,取得了两种保护算法下的业务阻塞率和资源预留比的数据。结果表明,优先共享保护通路算法能够有效地融合分段共享通路保护算法的优点,同时在业务的阻塞率和资源预留比方面优于分段共享保护通路算法。     

An efficient hybrid protection scheme with shared/dedicated backup paths on elastic optical networks

Fast recovery and minimum utilization of resources are the two main criteria for determining the protection scheme quality. We address the problem of providing a hybrid protection approach on elastic optical networks under contiguity and continuity of available spectrum constraints. Two main hypotheses are used in this paper for backup paths computation. In the first case, it is assumed that backup paths resources are dedicated. In the second case, the assumption is that backup paths resources are available shared resources. The objective of the study is to minimize spectrum utilization to reduce blocking probability on a network. For this purpose, an efficient survivable Hybrid Protection Lightpath (HybPL) algorithm is proposed for providing shared or dedicated backup path protection based on the efficient energy calculation and resource availability. Traditional First-Fit and Best-Fit schemes are employed to search and assign the available spectrum resources. The simulation results show that HybPL presents better performance in terms of blocking probability, compared with the Minimum Resources Utilization Dedicated Protection (MRU-DP) algorithm which offers better performance than the Dedicated Protection (DP) algorithm.     

A prototype broadcast-and-select photonic ATM switch with a WDMoutput buffer

A rack-mounted prototype of a broadcast-and-select (B and S) photonic ATM switch is fabricated. This switch has an optical output buffer utilizing wavelength division multiplexed (WDM) signals. The WDM technology solves. The cell-collision problem in a broadcast-and-select network and leads to a simple network architecture and the broadcast/multicast function. The prototype can handle 10-Gb/s nonreturn-to-zero (NRZ) coded cells and 5-Gb/s Manchester-coded cells and has a switch size of four. In this prototype, the level and timing design are key issues. Cell-by-cell level fluctuation is overcome by minimizing the loss difference between the optical paths and adopting a differential receiver capable of auto-thresholding. The temperature control of delay lines was successful in maintaining the phase synchronization. Using these techniques, we are able to provide a WDM highway with a bit error rate of less than 10^-12. Fundamental photonic ATM switching functions, such as optical buffering and fast wavelength-channel selection, are achieved. We show our experimental results and demonstrate the high performance and stable operation of a photonic ATM switch for use in high-speed optical switching systems as an interconnect switch for a modular ATM switch and an ATM cross-connect switch     

单双向OADM节点混合时的光环形网的保护

简单介绍了光环形网的几类保护形式和典型的单双向OADM结构，并进一步分析了单双向节点构成的混合环网的线路保护和通道保护以及双向节点的混合保护，还对节点的综合控制作了简单分析。     

光网络P圈保护方法分析

在光网络中,节点和链路故障是光网络生存性的关键因素。P圈保护被认为是一种非常有前途的保护方式,有着高效、高速等特点。对光网络中的P圈保护单故障和多故障的策略和方式进行分析,并分析了基于树和基于段的光组播P圈保护策略。最后,指出P圈保护在未来光网络中的研究发展方向。     

光网络的保护恢复的研究

随着波分复用(WDM)技术的飞速发展,光网络的生存性要求也越来越高,文章阐述了光网络中通用的几种保护方法,给出了这几种保护方法的特点及使用范围,并且就资源利用率、造价、倒换时间、对节点的要求和对网络拓扑的要求这几方面做了比较和分析。最后得出在不同的网络,不同的生存性要求和不同的负载的情况下应采取不同的保护恢复方法。     

无源光网络冗余保护及应用实现

PON网络相对于传统网络组网简单,无源传输,提供可观接入速率和多业务应用,得到了蓬勃发展。通过对PON网络组网结构以及业务特征的定性研究,分析了PON网络中不同保护方式对应的应用场景。并对在网络设计中考虑保护以及在组网各个节点进行冗余保护以及提升网络运行稳定性,提高用户体验感知的有效方法进行了总结。并对特殊应用下的PON网络结合和冗余保护实现进行分析总结。     

IP over WDM光网络的共享保护方式

共享保护方式是一种有效而又经济的保护方式。文章讨论了三种共享保护方式及各自的特点。使用交换光纤（OSF）的共享保护方式利用IP网络控制器来实现，主要应用于环形网络拓扑；利用OXC的共享保护方式基于多协议标记交换（MPLS）控制平面，可以用于任何网络拓扑结构；通过合理的逻辑拓扑而实现的共享保护则用于保护SONET/WDM和IP/WDM网络的设计。     

基于FTTH的光网络保护系统的研究

针对FTTH光纤线路的保护问题,提出了一种无源光网络光纤线路切换保护系统.光纤线路切换设备通过不同的光纤链路连接远端设备的两个光通信端口,当某一个与远端设备连接的分支光纤链路出现故障时,光纤线路切换设备通过连接备用的分支光纤链路,保障通信的及时恢复.实验结果表明,ONU能够在50ms内自动完成在光口1和光口2间的识别与光路保护切换,极大地提高了PON光纤线路保护的可靠性和生存性,有利于FTTH/B的应用.     

Reconfigurable OADM and OXC designed by a new optical switch

A new dynamically selective optical add/drop multiplexer (OADM) and optical cross-connect (OXC) configuration for dense wavelength division multiplexed (DWDM) networks are proposed. The selective devices are based on fiber Bragg gratings (FBGs), single-sided micro-mirror optical switches (OSWs), and optical circulators (OCs). They are flexible, expandable, and high capacity in DWDM networks if the basic units are cascaded in series. In this paper, fiber collimators in coupling are analyzed in order to characterize the insertion loss and output power equalization in OADM and OXC. “Off-the-shelf” DWDM communication products are used for analysis; as a result, the main insertion loss in the system comes from circulators while the maximum insertion loss deviation comes mainly from FBGs and micro-mirrors. As compared to the other existing reconfigurable OADMs and OXCs, the number of mirrors in the optical switch could be dramatically reduced. The reliability of optical switch operation, therefore, can be enhanced.     

Multicast service protection algorithm based on elastic optical network

With the rapid growth of the network traffic,the elastic optical network (EON) has been proposed as a promising solution due to its high spectrum efficiency and flexible bandwidth provision.Meanwhile,multicast routing and spectrum allocation,and the survivability of the network become more challenging than that in the conventional optical network.The routing for multicast traffic and its protection algorithm in EON was investigated.An integer linear programming (ILP) formulation with the objective to minimize total spectrum consumption was presented.In addition,a heuristic algorithm called multicast sub-tree protection algorithm (MSPA) to achieve sufficient protection and satisfy resources savings was designed.The simulation results demonstrate that comparing with the traditional multicast routing and protection algorithm,MSPA performs well in improving the blocking probability and the spectrum utilization of the network.     

光传送网环覆盖保护策略研究

生存性是光传送网络中亟待解决的问题.文章基于环网的优良保护倒换能力提出了环覆盖保护策略,给出了选择环覆盖的控制流程,建立了以保护容量需求作为优化目标的环覆盖优化设计模型.     

基于光纤光栅的新型光分插复用器

文章提出了一种基于光纤光栅的新型光分插复用器(OADM),并阐述了此新型OADM结构的复用和解复用原理,它具有插入损耗低、灵活性强和串扰低等优点.为验证结构设计和理论分析的正确性,用OptiSystem软件对所设计的OADM结构进行了仿真实验.仿真结果表明,下载波长的边模抑制比高达20 dB,此新型结构具有良好的性能和...