基于禁忌遗传算法求解路由和波长分配问题

静态的路由选择和波长分配(RWA)问题是WDM光网络中的一个重要问题,目前常用的处理方法是将RWA问题拆成选路子问题和波长分配子问题.静态RWA问题通常先按某种策略确定建立光路的顺序,然后用启发式算法加以解决.提出通过禁忌遗传算法对光路的建立顺序进行优化,然后用基于爬山算法的启发式算法来求解以波长数最小为优化目标的静态RWA问题.通过对ARPANet等5种实际光网络的仿真表明,提出的算法和文献[5]相比,所用的波长数更少,且大部分优化结果达到最优.     

基于WDM传输网的动态路由算法

波分复用技术(WDM)作为一种公认的最佳光纤扩容技术已被广泛应用在国际和国内长途骨干网上。路由算法与波长分配(RWA)是WDM网中的重要技术之一,评价RWA算法的一个重要标准是网络阻塞率。采用合适的路由算法可以大大降低网络的阻塞率。该文采用一种结合了再生节点选择的动态RWA算法来解决WDM网中的波长路由问题,并通过光纤通道拓扑的优化算法来进一步优化。通过建模仿真,研究了NSFNET网络优化前后阻塞率的变化,仿真的结果证明采用该优化算法可以降低网络的阻塞率。     

有效的光传送网路由及波长分配算法

研究了光传送网路由及波长分配问题，对于虚波长网络以波长优化为目的，给出了两种启发式算法，并提出了波长数减一代价，作为对算法另一评判依据，通过对仿真结果的分析，来研究所提出算法的有效性。     

SRLG分离的静态RWA保护算法

对于静态业务,传统RWA算法仅仅着眼于通过合理的选路和波长分配算法来建立相应的光路,使网络成本最小化。本文从提高网络生存性的角度出发,结合共享风险链路组的概念,讨论了抗毁WDM网络中的静态RWA保护设计算法。根据实现方式的不同将其分为两类:并行算法和分解算法,并分别进行了讨论。     

基于遗传算法的动态RWA问题的研究

针对WDM光传送网中的动态路由选择和波长分配(RWA)问题,提出了一种基于遗传算法的动态RWA方法。将遗传算法与相对容量影响(RCI)波长分配算法相结合,以实现对RWA算法的改进。仿真结果表明,与现有最短路径算法[1]相比,该算法能有效提高网络资源利用率,促进波长资源的合理分配。     

多粒度光网络中动态路由与波长分配算法

通过分析多粒度光网络路由与波长分配的特点,针对WAPG算法的波长碎片问题,通过定义5种不同的逻辑链路权重,修改了WAPG算法的波长权重标注方法,达到减少波长碎片的目的。仿真结果表明,提出的修正算法有效地减少了多粒度光网络中的波长转换数,降低网络的阻塞概率,同时节省网络资源。     

一种稀疏波长转换光网络中的波长分配算法

研究了具有波长转换功能的WDM光网络的分类以及已有的几种波长分配算法,分析了波长分配算法的一般流程。文中以波长变换次数最少做为所提出的波长分配算法的主要优化目标,根据WDM光网络中的节点是否具有波长转换的功能,结合等价光路由替换的思想,提出了在稀疏有限波长转换光网络中的一种启发式的波长分配算法。仿真实验表明,当光网络中的连接请求量较大时,该算法的阻塞率低于已有的一些波长分配算法,连接能力有了较大提高。     

波长路由光网络相关问题分析

光纤凭借着带宽大和传输损耗小的特点逐渐代替了铜缆,并且是干线网一种重要传输介质。文章重点对波长路由光网进行了深入的探究和分析,详细指出波长路由光网络所具有的优势,同时针对波长路光网络中的RWA问题和波长路由光网络中故障管理的问题进行了分析。     

一种稀疏波长转换光网络中的波长分配算法

研究了具有波长转换功能的WDM光网络的分类以及已有的几种波长分配算法，分析了波长分配算法的一般流程。文中以波长变换次数最少做为所提出的波长分配算法的主要优化目标，根据WDM光网络中的节点是否具有波长转换的功能，结合等价光路由替换的思想，提出了在稀疏有限波长转换光网络中的一种启发式的波长分配算法。仿真实验表明，当光网络中的连接请求量较大时，该算法的阻塞率低于已有的一些波长分配算法，连接能力有了较大提高。     

基于OWns的WDM光网络仿真软件RwaOWns的开发

OWns是基于ns的WDM光网络仿真软件,被人们广泛用于光网络的研究.仿真软件RwaOWns扩充OWns以支持多种RWA算法,提供一个对多种RWA算法进行性能比较的平台,且有一个简便的RWA算法模块加入接口.给出了RwaOWns的总体结构和详细的设计,描述了如何编写新的RWA算法模块,最后给出了使用RwaOWns软件进行仿真的方法.     

DWDM光网络中RWA问题的遗传求解方法

针对密集波分复用(dense wavelength-division multiplexing,DWDM)光网络通信中的动态路由与波长分配(routing and wavelength assignment,RWA)问题,提出了一种基于遗传算法的动态RWA方法.将遗传算法与分层图模型相结合,实现了RWA的方便计算.通过扩展适应值函数,能够有效地处理带时延约束的通信量请求.实验结果表明,与已有最短路径算法(Dijks-tra)相比,该算法能够提供多条候选路由方案,更适应较差环境下的网络通信.     

A novel model on dynamic resource allocation in optical networks

A novel model on dynamic resource allocation in the WDM optical networks is proposed, basing on the integrated considerations of the impacts of transmission impairments and service classification on dynamic resource allocation in the optical layer. In this model, the priorities of optical connection requests are mapped into different thresholds of transmission impairments, and a uniform method which is adopted to evaluate the virtual wavelength path (VWP) candidates is defined. The Advanced Preferred Wavelength Sets Algorithm (A-PWS) and the heuristic Dynamic Min-Cost & Optical Virtual Wavelength Path Algorithm (DMC-OVWP) are presented addressing the routing and wavelength assignment (RWA) problem based on dynamic traffic and multi priorities in wavelength-routed optical networks. For a received optical connection request, DMC-OVWP is employed to calculate a list of the VWP candidates, and an appropriate VWP which matches the request's priority is picked up to establish the lightpath by analyzing the tra     

Particle swarm optimization-based DRWA for wavelength continuous WDM optical networks using a novel fitness function

Greater demand of bandwidth and network usage flexibility from customers along with new automated means for network resource management has led to the concept of dynamic resource provisioning in WDM optical networks where unlike the traditional static channel assignment process, network resources can be assigned dynamically. This paper examines a novel particle swarm optimization (PSO)-based scheme to solve dynamic routing and wavelength assignment (dynamic RWA) process needed to provision optical channels for wavelength continuous Wavelength Division Multiplexed (WDM) optical network without any wavelength conversion capability. The proposed PSO scheme employs a novel fitness function which is used during quantization of solutions represented by respective particles of the swarm. The proposed fitness function takes into account the normalized path length of the chosen route and the normalized number of free wavelengths available over the whole route, enabling the PSO-based scheme to be self-tuning by minimizing the need to have a dynamic algorithmic parameter ‘α’ needed for better performance in terms of blocking probability of the connection requests. Simulation results show better performance of the proposed PSO scheme employing novel fitness function for solving dynamic RWA problem, not only in terms of connection blocking probability but also route computation time as compared to other evolutionary schemes like genetic algorithms.     

Routing and wavelength assignment with power considerations in optical networks

Previous studies have solved many variations of the routing and wavelength assignment (RWA) problem in optical networks under the assumption of perfect conditions regarding the power of a signal. In this paper, we investigate the RWA problem while allowing for degradation of routed signals by optical components. The problem is formulated as a mixed-integer non-linear program. We propose a two-phase approach. In the first phase, we solve the pure RWA problem using fixed routes for every connection. In the second phase, power assignment is accomplished by either using a heuristic or using a genetic algorithm. This paper demonstrates that: (i) connections do interact affecting the power of each other, and (ii) global search meta-heuristics provide better solutions.     

WDM全光网络中优化组播路由的遗传算法

在WDM网络中，路由和波长分配是紧密联系在一起的，即在建立光连接的过程中，不但需要确定路由，还要为该路由分配合适的波长资源。该文给出了一种遗传算法以解决在给定一组时延受限的组播请求的情况下，如何为这些组播请求建立合适的组播路由树，从而使得该组组播树所占用的波长数最小的问题。通过使用一种合适的二维染色体编码表示，并设计适合问题的交叉和变异操作，从而算法可以有效地搜索假设空间，实验模拟结果表明了该算法具有快速有效的特点。     

基于禁忌搜索算法求解全光网路由和波长分配问题

该文是基于禁忌搜索算法对一类全光网路由和波长分配MAX-RWA问题进行求解．该文针对配置范围受限波长转换器的全光网，强化了MAX-RWA问题的优化目标．新的优化目标是保证连接数最多的情况下使用最少的波长转换器，从而尽可能地减少波长转换器引入的信号失真；简化了文献[7]中分层图的构造方法，并利用改进的分层图给出了MAX-RWA问题的整数线性规划和禁忌搜索算法的设计．仿真结果和理论上界的对比表明该文算法是稳定、有效的．     

并行BP算法在WDM环网上的波长分配

波长分配是光网络设计的基本问题,设计波长分配算法是洞察光网络通信能力的基本方法。不同的并行算法具有不同的通信模式,如何在光互联网上实现这些通信模式,同时优化波长分配问题,是当前一个颇受关注的研究领域。神经网络计算的一个重要特点是大规模并行计算,该文基于WDM环网络,讨论了在其上实现并行BP算法的波长分配问题,设计了将完全二分图结构Kmn,通信模式嵌入环网的方案,给出了在WDM环网络上实现并行BP算法所需的最小波长数。     

Traffic grooming, routing, and wavelength assignment in WDM transport networks with sparse grooming resources

While a single fiber strand in wavelength division multiplexing (WDM) has over a terabit-per-second bandwidth and a wavelength channel has over a gigabit-per-second transmission speed, the network may still be required to support traffic requests at rates that are lower than the full wavelength capacity. To avoid assigning an entire lightpath to a small request, many researchers have looked at adding traffic grooming to the routing and wavelength assignment (RWA) problem. In this work, we consider the RWA problem with traffic grooming (GRWA) for mesh networks under static and dynamic lightpath connection requests. The GRWA problem is NP-Complete since it is a generalization of the RWA problem which is known to be NP-Complete. We propose an integer linear programming (ILP) model that accurately depicts the GRWA problem. Because it is very hard to find a solution for large networks using ILP, we solve the GRWA problem by proposing two novel heuristics. The strength of the proposed heuristics stems from their simplicity, efficiency, and applicability to large-scale networks. Our simulation results demonstrate that deploying traffic grooming resources on the edge of optical networks is more cost effective and results in a similar blocking performance to that obtained when distributing the grooming resources throughout the optical network domain.