波分复用波长路由节点的阻塞特性分析

利用概率统计理论的方法，从节点层次上定量分析了节点规模、复用波长数目以及波长转换对波分复用(WDM)波长路由网络中波长路由节点的影响。提出了基于概率统计的节点阻塞模型。数值结果突出表明波长转换能力越强的全光节点，其性能越优。为了提高网络资源的使用效率并增强全光网络的灵活性，必须实现全光网络中的虚波长路由波长转换器。通过数值计算找到了阻塞性能和代价的折中，研究中发现配置较低波长转换能力波长转换器的波长路由节点将会具备更强的性价比优势，当前在构建光通信系统时使用弱波长转换能力的光节点更可行。     

全光波长转换器的原理和特性的比较

全光波长转换器件是未来全光网的一个关键器件，可以广泛地用作为光开关、光交换、波长路由、波长再用等，从而使波分复用系统的管理更为灵活、合理、可靠。本文介绍全光波长转换的基本原理、特性及其研究进展。     

LiNbO3声光可调谐滤波器(AOTF)在OADM中的应用

基于LiNbO3晶体的声光可调谐滤波器(AOTF)是利用TE/TM模式转换的原理实现了多波长选择特性和宽调谐范围,这使它在波分复用(WDM)中的光分插复用(OADM)系统中有广泛用途.文章介绍了AOTF的基本原理,以及用它构成的OADM系统.     

全光波长转换技术

全光波长转换器将是未来波分复用（WDM）网络中的关键器件之一，它允许波长重用，避免波长竞争，它还能够提供波长重构与分散管理。本文主要介绍全光波长转换的方法、原理、特性及进展。     

全光波长转换器件开发现状

波长转换是实现光子网络(Photonic Network)中的灵活波长控制的关键技术之一。在光子网络的光互连节点上,波长转换技术的应用能够降低通道阻塞的概率,并能实现波长的重复使用。波长资源的有效利用也有利于促进灵活网络的构筑。全光波长转换(All-Optical WavelengthConversion)由于无需光电(OE)/电光(EO)转换器件,而且不受光信号格式(Signal Format)及位速率的限制,使得光子网络具有透明性,其自身也因此成为一项引人关注的技术。本文将扼要介绍一些有关全光波长转换器件的研发现状。一、光子网络中的波长转换技术波长转换器件的基本要求…     

用温度控制可调谐激光器波长稳定的方法

介绍了可调谐半导体激光器在光通信领域的应用及其工作原理.重点讨论了SSG-DBR可调谐激光器的结构、工作原理,以及波长稳定控制方法.提出了一种新的基于温度反馈的波长稳定控制方法,使可调谐激光器的输出在20℃～70℃范围内的波长漂移小于1nm,边模抑制比优于5dB.该方法简单、可靠,将会对可调谐激光器在全光网络中的应用起到一定的推动作用.     

基于8×8 MEMS的全光OXC结构设计及性能仿真

设计了一种新型的全光节点交叉连接设备(OXC),它由4个8×8 MEMS光交换模块、2个星形耦合器、3个可调谐滤波器、5个波分复用/解复用器和7个波长变换器组成.对这种OXC光谱特性和噪声性能进行仿真,结果表明,该OXC可提供全光交叉连接、广播发送、波长变换以及链路升级等功能,适用于40Gb/s的超高速全光通信系统.     

全光波长转换技术在混合WDM/OTDM网络节点中的应用与实验进展

简单分析了未来全光通信网中光波分复用(WDM)和光时分复用(OTDM)技术组合使用的必要性,讨论了各种全光波长转换技术在混合的WDM/OTDM网络结点中的应用,并结合实验进展介绍了各种转换技术的原理和特性。     

全光光孤子WDM到OTDM转换的概念系统

提出了在未来的光孤子波分复／时分复用网络中由ＷＤＭ到ＯＴＤＭ节点处的转换复用的概念系统，主要的模块是完成波长转换的基于交叉增益调制的半导体光放大器，同步和延时及时分复用模块。通过ＳＯＡ可以实现全光的ＷＤＭ到ＯＴＤＭ的波长转换复用，是ＷＤＭ／ＯＴＤＭ网络实用化的一个关键部分。     

10G波分时分混合复用无源光网络设计

分析了现有主要的两种无源光网络技术的利弊,创造性地提出融合WDM-PON、TDM-PON、多波长光源、无热周期AWG和全光波长转换等技术的10G波分时分混合复用无源光网络架构,叙述其工作原理,并详细描述各网元节点的模块构成及技术核心点.     

Performance analysis of multi-fiber WDM network with limited-range wavelength conversion

Wavelength routed optical networks have emerged as a technology that can effectively utilize the enormous bandwidth of the optical fiber. Wavelength conversion technology and wavelength converters play an important role in enhancing fiber utilization and in reducing the overall call blocking probability of the network. In this paper, we develop a new analytical model to calculate the average blocking probability in multi-fiber link networks using limited-range wavelength conversion. Based on the results obtained, we conclude that the proposed analytical model is simple and yet can effectively analyze the impact of wavelength conversion ranges and number of fibers on network performance. Also a new heuristic approach for placement of wavelength converters to reduce blocking probabilities is explored. Finally, we analyze network performance with the proposed scheme. It can be observed from numerical simulations that limited-range converters placed at a few nodes can provide almost the same blocking probability as full range wavelength converters placed at all the nodes. We also show that being equipped with a multi-fiber per-link has the same effect as being equipped with the capability of limited-range wavelength conversion. So a multi-fiber per-link network using limited-range wavelength conversion has similar blocking performance as a full wavelength convertible network. Since a multi-fiber network using limited-range wavelength conversion could use fewer converters than a single-fiber network using limited range wavelength conversion and because wavelength converters are today more expensive than fiber equipment, a multi-fiber network in condition with limited-range wavelength conversion is less costly than a single-fiber network using only limited-range wavelength conversion. Thus, multi-fiber per-link network using limited-range wavelength conversion is currently a more practical method for all optical WDM networks. Simulation studies carried out on a 14-node NSFNET, a 10-node CERNET (China Education and Research Network), and a 9-node regular mesh network validate the analysis.     

Blocking performance analysis on adaptive routing over WDM networks with finite wavelength conversion capability

Analytical blocking probability analysis is important for network design. In this paper, we present an analytical model for the blocking probability analysis on adaptive routing over the WDM networks with finite wavelength conversion capability. Modeling the finite nature of wavelength conversion has been a difficult task. We make use of the idea of segmented route to handle the finite wavelength conversion property. In this approach, a route is divided into a number of segments separated by wavelength converting nodes. We then combine the single-link model and the overflow model to derive the network-wide blocking probability. There are two distinct features in our technique. First, a concept of segmented route is used. Second, link state is considered when calculating the traffic flow. The latter ensures that the analytical results match closely to practical network status. Extensive simulations show that the analytical technique is effective in modeling the blocking probability performance for sparse networks.     

A Node-Level Blocking Probability Analysis for WRONs

This work presents the blocking performance of a single node with (full or limited) wavelength conversion in wavelength routed optical networks (WRON) based on the theory of probability. A blocking probability model is proposed. Particularly, we pay more attention to investigate wavelength routing node performance improvement by using the more feasible case of limited wavelength conversion. Based on our analytical model, we calculate the blocking probability for a single wavelength routing node and then make a simulation to validate it. It is shown that a node with low conversion degrees having a small number of fiber link ports and a large number of wavelengths per link is a more realistic choice.     

Design-dimensioning model for transparent WDM packet-switchedirregular networks

A detailed analytical traffic model for all-optical wavelength division multiplexing (WDM) photonic packet-switched networks is presented and the requirements for buffer size and link dimensions are analyzed. This paper shows that due to the topology, packets may generate traffic bottlenecks produced by a tendency of the routing scheme to send packets with different destinations through preferred paths. This effect increases the traffic load and, hence, the probability of blocking at the output links of specific routers in the network and, therefore, a large buffer depth or an increment in the number of fibers per link is required. Three router architectures are analyzed and it is shown that WDM all-optical router architectures with shared contention resolution resources are the best candidates to reduce hardware volume and cost of all-optical networks. It is shown that routers with a bank of completely shared wavelength converters (WCs) require a fraction of WCs compared to router architectures that use a WC per wavelength. This fraction depends on the location of the router, the network topology, and the traffic load in the network. However, in general terms, about 50% to 90% of WCs can be saved by architectures with shared wavelength-conversion resources. Also, it is shown that limited wavelength conversion degrees d=8 and d=10 in packet-switching routers with 16 and 32 wavelengths give the same probability of packet loss performance as full wavelength conversion     

备用路由下一种新的WDM动态路由波长分配算法

基于波长转换度的空闲波长图模型,提出了一种用于WDM光网络在备选路由下的动态RWA算法。路由选择采用K条最短路径算法进行,备选路由集中首选最佳路由时考虑链路的代价、跳数和每一个链路上不可用波长数。通过计算机模拟,分析这3个参数对网络的阻塞率的影响,结果表明本算法中所选定研究的3个参数中选定路由的不可用波长数对网络阻塞率的影响程度比通道的代价,跳数对网络的影响程度大,这个结论对算法中这3个参数数值的选取提供了依据,使算法能够依据实际网络情况动态选取参数,降低网络阻塞率。     

An efficient dynamic distributed optical link establish method in intelligent all-optical networks

In this article, an efficient, fast, and dynamic distributed optical link setup method is proposed. Two kinds of novel optical fast link release mechanisms (Ahead and Timeout Release) are presented for an optical-link establishment. They can dramatically reduce the blocking probability. For dynamic routing detection, a new kind of dynamic weighted Dijkstra algorithm (DW-DA) along with dynamic optical link load balancing is described. A variable mutation and crossover rates of a genetic algorithm (VMCR-GA) is used for fast wavelength assignment with two-novel-wavelength assignment rules in a wavelength relationship graph, which can reduce the necessary wavelengths and link establishment time. Through simulation giving the blocking probability and the time for link establishment on several well-known networks, the effectiveness of this method has been verified. The blocking probability of the network can be reduced significantly below that of normal routing and wavelength assignment (RWA). Furthermore, the calculating time for reaching the minimum blocking probability can be reduced dramatically.

Analysis of blocking probability in optical burst switched networks

In this article, we study the blocking probability in a wavelength division multiplexing (WDM) based asynchronous bufferless optical burst switched (OBS) network, equipped with a bank of wavelength converters. Our analysis encloses two wavelength reservation schemes JIT (just-in-time) and JET (just-enough-time), and two-class data rate. The contribution of our work includes: (i) derivation of an accurate model for blocking probability of lower priority bursts in case of a non-preempted model; (ii) provision of the analytical model for blocking probability calculation in the OBS network, which includes these variables: two signaling schemes, partial wavelength conversion, two-class data, traffic intensity, cross-connect speed, number of wavelengths in WDM fiber, number of fibers in the node, number of wavelength converters, and number of nodes in the path; (iii) simulation results, which show that partial wavelength conversion provide quite satisfactory quality of service. We compare performance in a single OBS node, under various sets of parameter values. The OBS network shows great flexibility in terms of used multiclass data, and there is no dependence on the used higher layer protocol.     

Performance Analysis of Multi-Fiber WDM Network with Limited-Range Wavelength Conversion

Wavelength routed optical networks have emerged as a technology that can effectively utilize the enormous bandwidth of the optical fiber. Wavelength conversion technology and wavelength converters play an important role in enhancing fiber utilization and in reducing the overall call blocking probability of the network. In this paper, we develop a new analytical model to calculate the average blocking probability in multi-fiber link networks using limited range wavelength conversion. Based on the results obtained, we conclude that the proposed analytical model is simple and yet can effectively analyze the impact of wavelength conversion ranges and number of fibers on network performance. Also a new heuristic approach for placement of wavelength converters to reduce blocking probabilities is explored. Finally, we analyze network performance with the proposed scheme. It can be observed from numerical simulations that limited range converters placed at a few nodes can provide almost the same blocking probability as full range wavelength converters placed at all the nodes. We also show that being equipped with a multi-fiber per-link has the same effect as being equipped with the capability of limited range wavelength conversion. So a multi-fiber per-link network using limited range wavelength conversion has similar blocking performance as a full wavelength convertible network. Since a multi-fiber network using limited range wavelength conversion could use fewer converters than a single-fiber network using limited range wavelength conversion and because wavelength converters are today more expensive than fiber equipment, a multi-fiber network in condition with limited range wavelength conversion is less costly than a single fiber network using only limited range wavelength conversion. Thus, multi-fiber per-link network using limited range wavelength conversion is currently a more practical method for all optical WDM networks. Simulation studies carried out on a 14-node NSFNET, a 10-node CERNET (China Education and Research Network), and a 9-node regular mesh network validate the analysis.     

Performance Evaluations for Dynamic Wavelength Routed All-Optical Multifiber Networks

This paper presents a study on dynamic wavelength routed all-optical networks by simulating traffic on all-optical networks. A performance study is carried out on dynamic all-optical networks for fixed and free routing. It is explained how multiple fibers correspond to limited wavelength conversion, and it is explained why the presence of wavelength converters increase the complexity of optical cross connects. We find that both free routing and wavelength conversion lowers the blocking probability significantly. The new contribution is that we determine the gain in blocking probability as function of the number of fibers per link and the offered load. We find that multiple fibers reduce the effect of wavelength converters significantly.