一种基于WDM光网络的静态波长路由优化算法

研究了WDM光网络中的静态波长路由问题,基于负载的均衡可以改善网络的性能这一事实,提出了一种优化的路由算法(O-Spread算法),文中进行了算法仿真,结果表明优化算法与传统的最短路由算法相比,能够有效地减小网络对于波长数目的需求。     

WDM网络中的一种波长分配算法

本文研究了动态业务下，采用固定选路和备用选路的波分复用光传送网中的波长分配问题，提出了一种波长分配算法-相对最小影响算法。与己朋的利用全网信息分配波长的算法相比，该算法能更精确地描述波长分配对全网状态的影响，使网络资源的充分利用成为可能。计算机仿真表明，该波长分配算法性能较好。     

Minimum connection count wavelength assignment strategy for WDM optical networks

In this paper, we have proposed one wavelength assignment strategy for optical networks which assigns the wavelength according to minimum connection count. The performance of proposed strategy is compared with the most commonly used strategy among the existing strategies in terms of number of searches to find the wavelength for connection establishment. The searching takes the time and directly affects the connection establishment time. The simulation is done using different network models. The results show that the proposed strategy is much better than existing strategy in terms of number of searches required to find a wavelength for establishing the connection and hence connection establishment time reduces.     

基于节点功能的WDM光网络分布式路由与波长分配算法

建立了一种具有节点功能区分的WDM多波长光网络模型,根据节点功能将其分为A、B两类,在此基础上提出了波长等价弧和等价网络等概念,并根据此类多波长光网络模型的节点和网络结构特点以及相应的选路和波长分配策略,提出了一种基于节点功能的多波长光网络分布式路由与波长分配算法——BONF算法,证明了算法的可行性,分析了算法的计算复杂度,比较了此算法与其它同类型算法的区别,指出了BONF算法的优点和不足。     

一种公平的多优先级WDM光网络波长分配算法

文章研究了波分复用(WDM)光网络中动态业务下的波长分配问题,在无波长转换器的条件下,提出了一种加入了公平性考虑的动态门限算法.该算法在支持多优先级的动态门限法的基础上,通过更新初始优先级减少了不同距离光路连接请求间的阻塞率差别,改善了公平性.计算机仿真结果说明了该算法的有效性.     

WDM光网络中固定路由的优化算法

通过研究WDM光网络中固定路由策略的选取对网络性能的影响，提出了一种新的用于优化固定路由的算法-综合代价法。该算法综合考虑了链路负载和路由跳数这两个因素，以综合代价为策略进行路由优化。计算机仿真结果表明，针对不同的网络负载情况，综合代价法能够有效地降低网络的阻塞率，提高网络的性能。     

WDM光网络中一种改进的波长转换器配置算法

文章在一种已有的"子图+ADD(代数决策图)"的波长转换器配置算法的基础上,提出了用优先配置最大度节点的启发式思想对该算法进行改进,得到了新的"子图+BDF(大度节点优先分配)"算法.通过对两种算法进行计算机仿真,得到的模拟结果显示新算法在保持结果准确的同时,有效降低了运算的时间复杂度.     

一种改进遗传算法在WDM光网络中的应用

在波长路由光网(WRON)中,波长转换对提高网络性能、减少阻塞率起着重要的作用.但由于目前全光波长转换器非常昂贵,因而如何最优利用波长转换是配置光网络的一个重要问题.文中利用遗传算法很好地解决了这一问题,并且利用数值模拟的方法,计算了美国自然科学基金网(NSFnet)网络中最优配置下网络的阻塞情况.然后针对普通遗传算法的缺点,提出了一种改进遗传算法.最后利用数值模拟的方法,比较了两种算法的性能.     

Study of multicast wavelength arrangement for maximizing network capacity in WDM networks with sparse wavelength converters

The issue of wavelength assignment is one of the most important factors that affect the capacity for the deployment of optical networks. This issue becomes more critical for multicast connections, especially when the network nodes have no wavelength conversion capability. Although the wavelength assignment can be more flexible if each node can perform wavelength conversion, the deployment cost increases accordingly. A compromise is to support a limited portion of conversion nodes in the WDM network. We propose a systematic approach for the wavelength assignment of multicast connections in WDM networks with sparse wavelength conversion nodes. The efficiency of the arrangement of wavelength is measured by its influences on the available capacity of the network and the consumption of wavelengths. By using the proposed approach, the Static Cost Greedy (SCG) algorithm [8] can be easily extended to be applicable in a Sparse Wavelength Conversion Network (SWCN). In addition, instead of SCG, the Minimum-Effect-First (MEF) algorithm is proposed to maximize the network capacity during wavelength assignment. We compare the performance of the proposed MEF methods with the extended SCG scheme through exhaustive simulations. The experimental results indicate that the proposed MEF schemes demonstrate much better performance than the SCG scheme. We also found that the performance is not always improved proportionally to the increment of the wavelength conversion nodes. The improvement reaches saturation when the number of conversion nodes is above 35% of the total number of nodes.

Adaptive alternate routing in WDM networks and its performance tradeoffs in the presence of wavelength converters

Routing in wavelength-routed all-optical WDM networks has received much attention in the past decade, for which fixed and dynamic routing methods have been proposed. Taking into account the observation that wavelength-routed all-optical WDM networks are similar to circuit-switched voice networks, except with regard to wavelength conversion, we propose an adaptive alternate routing (AAR) scheme for wavelength-routed all-optical WDM networks. A major benefit of AAR is that it can operate and adapt without requiring an exchange of network status, i.e., it is an information-less adaptive routing scheme. The scope of this work is to understand this scheme in its own right since no other dynamic routing schemes are known to have the information-less property. In this paper, we conduct a systematic study of AAR with regard to factors such as the number of converters, load conditions, traffic patterns, network topologies, and the number of alternate paths considered. We observe that the routing scheme with multiple alternate routes provides more gain at a lower load instead of requiring any nodes to be equipped with wavelength converters. On the other hand, the availability of wavelength converters at some nodes, along with adaptive routing, is beneficial at a moderate to high load without requiring all nodes to be equipped with wavelength converters. We also observed that a small number of alternate routes considered in a network without wavelength converters gives a much better performance than a network with full wavelength converters and fewer alternate routes. Throughout this study, we observed that the proposed adaptive alternate routing scheme adapts well to the network traffic condition.     

WDM网络中基于均衡策略的波长分配算法

对WDM光网络中的波长分配问题进行了研究,采用波长均衡分配的思路解决瓶颈容量对网络性能的影响,并给出了一种启发式算法--最大剩余瓶颈容量算法(Maximum Bottleneck Capacity,MaxBC).该算法把负载引起的波长损失均衡地分布在网络中,使得链路的信道容量受到的影响更小.通过仿真比较了MaxBC与MaxSum、RCL算法在网络拥塞概率等网络性能上的优劣.     

WDM光网络中一种备用路由下支持优先级的波长分配算法

研究了WDM光网络中的动态业务下的波长分配问题,在无波长转换器的条件下提出了一种改进的动态门限算法.该算法不仅能保证高优先级请求有较低的阻塞率,同时还能优化低优先级请求的阻塞率,从而改善全网的平均阻塞率.此外,该算法利用负载均衡算法,能更加精确地描述波长分配对全网状态的影响,从而更加有效地利用了网络资源.计算机仿真结果证明了该算法的有效性.     

WDM光传送网中支持优先级的波长分配算法

文中提出了一种用于WDM光传送网的支持优先级的波长分配算法－动态门限法,该算法保证了较高优先级的光路建立请求具有较低的阻塞率,同时又考虑到较低优先级的光路建立请求的性能优化,从而很好地降低了全网的平均阻塞率。文中给出了计算机仿结果。     

WDM网络中支持优先级的波长分配算法

本文提出了一种在WDM网络中支持优先级的波长分配算法,通过计算相对容量损失,力图在对较高优先级光路建立请求进行波长分配时,找到对较优先级请求影响最小的波长分配方案,这样,该算法既保证了较高优先级光路建立请求具有较低的阻塞率,同时又对较低优先级请求进行了优化,从而改善了全网的平均阻塞率。文中给出了计算机仿真结果。     

A protocol for piggy-backing on Markov based wavelength reservation in WDM optical networks

During lightpath establishment in WDM optical networks, two important steps, other than routing, are: wavelength selection and wavelength reservation. If two or more lightpaths select the same wavelength, wavelength collision occurs. The basic reason for collision is the non-availability of the updated wavelength usage information. Markov based wavelength selection guesses a unique wavelength in advance, where each node periodically broadcasts its adjoining link usage information at a regular interval T. But, at any intermediate time t (0<t<T), all nodes use the old update which is already outdated by time t. If T is large, the problem becomes severe. To get around this problem without introducing any extra overhead, we propose a novel technique where the normal control packets, passing through the relevant nodes during [0,T], can be leveraged to carry the desired link state information. This may allow us even to increase the value of T (thereby reducing broadcast overhead), when control packets are frequent in the network. We apply the proposed modification to our previous work on Markov selection Split Reservation Protocol (MSRP) and call the modified protocol Fast updated MSRP (FMSRP). In fast update, we “piggy-back” normal control packets with link usage information, in addition to the usual periodic broadcasting of the same at every T. It obviously increases the chance for the nodes to get the latest information of link usage. We have simulated FMSRP and compared it with MSRP and also with another current best protocol (i.e., Markov based Backward Reservation Protocol) to show that the blocking probability for FMSRP improves considerably over them in some regions of offered load.     

全光网静态路由选择和波长分配的分层图算法

文章提出一种将路由选择和波长分配结合起来的启发式的路由选择和波长分配(RWA)算法．通过这种新的分层图算法和限制光跳距的加权系数来优化全光网的静态路由选择和波长分配,使建立光连接时所需的波长数达到最少．最后对实际的ARPANet等5种光网络进行了计算机仿真,证明了本算法比以前的算法有更好的性能．     

光分组交换中的波长变换器配置研究

首先对波长变换器的功能及分类进行详细的论述,然后,对波长变换器的配置进行分析,总结出两种波长变换器配置方法,即独占式配置方法和共享式配置方法.针对独占式配置方法,本文使用仿真实验的方法研究了在不同类型的波长变换器下交换节点丢包性能的差异.本文还对独占式配置方法和共享式配置方法进行对比研究.     

WDM光网络中的业务量疏导

波分复用（WDM）技术在主干传送网中巳广泛应用，WDM光网络的研究进展也非常迅速，光网络中的业务量疏导定义为复用、解复用和交换低速率业务流到大容量的光路中的行为。介绍了WDM光网络的业务量疏导的重要性，研究方法及其最新研究进展情况。     

Design of grooming architectures for optical WDM mesh networks: limited grooming with electronic wavelength conversion

In this article, we consider the problem of traffic grooming in optical wavelength division multiplexed (WDM) mesh networks under static traffic conditions. The objective of this work is to minimize the network cost and in particular, the electronic port costs incurred for meeting a given performance objective. In earlier work, we have shown the benefits of limited grooming switch architectures, where only a subset of wavelengths in a network are equipped with expensive SONET Add Drop Multiplexers (SADM) that provide the grooming functionality. In this work, we also consider the wavelength conversion capability of such groomers. This can be achieved using a digital cross-connect (DCS) in the grooming switch to switch low-speed connections between the SADMs (and hence, between wavelengths). The grooming switch thus avoids the need for expensive optical wavelength converters. Based on these observations, we propose a limited conversion-based grooming architecture for optical WDM mesh networks. The local ports at every node in this architecture can be one of three types: an add-drop port, a grooming port that allows wavelength conversion or a grooming port that does not allow wavelength conversion. The problem studied is: given a static traffic model, where should the different ports be placed in a network? We formulate this as an optimization problem using an Integer Linear Programing (ILP) and present numerical results for the same. We also present a heuristic-based approach to solve the problem for larger networks.     

一种新型基于子图的波长转换器配置算法

文章在已有的"子图+ADD(代数决策图)"波长转换器配置算法的基础上,将节点在路由上的平均中心距离作为权值对节点进行排序,提出了用优先配置中心节点的启发式思想对该算法进行优化,得到了新的算法,即"子图+CNF(中心节点优先分配)"算法。对本算法进行计算机仿真,结果显示新算法在保证结果准确的同时,有效降低了运算的时间复杂度。