【作者】 刘松；

【导师】 何健；

【作者基本信息】 华中科技大学 ， 光电信息工程， 2011， 硕士

【摘要】 路由选择与波长分配(RWA)是光网络中一个重要的问题。它是指在源节点到目的节点之间有通信需求时，如何寻找从源节点到目的节点的路由，以及为该路由分配合适的波长。一个好的RWA算法，能极大的提升网络性能，改善网络阻塞率，均衡网络业务流量，所以人们热衷于研究RWA算法。很多论文对RWA的研究都是在理想网络的基础上进行的，这个并不实际，有很多缺点。虽然不可能建立绝对的实际网络模型，但是通络考虑某些损伤，可以使得RWA算法能更贴近实际。为了更好的解决RWA问题，本论文提出了一种能延时缓存的损失感知波长路由算法(Routing and Wavelength Assignment base on Delay Buffer with Impairment Aware. DB_IA_RWA)。该算法假定的损伤为偏振模色散(PMD)和自发辐射噪声(ASE)。该算法在寻找光通道时，把物理层损伤作为波长路由的一个限制条件。如果没有为呼叫请求找到一个合适的光通道，则把此次呼叫请求缓存，延迟一段时间后，再次为CR寻找光通道。如果CR的缓存时间到达门限值，把CR从缓存队列中删除，一次呼叫阻塞。该算法是一种基于分层图的模型，使得路由和波长分配同时完成。在没有波长转换器的条件下，该算法能动态调整选路策略，达到资源的合理利用。最后仿真证明该算法能有效降低网络阻塞率！本文的具体工作包括以下内容：(1)介绍了波长路由算法，并给出了D算法和G算法的流程图。(2)然后给出了本论文所假设的损失模型，延时缓存模块的算法流程图。(3)用OPNET研究了理想网络中传统RWA算法(T_RWA)；实际网络中的RWA算法(RWA_real)；损失感知的RWA算法(IA_RWA)的阻塞率性能。对其中具体的收发包情况进行了统计。(4)最后用OPNET仿真软件对所提出的DB_IA_RWA算法进行仿真模拟，结果显示与其他考虑损失RWA算法相比，这个算法能改善相关阻塞率性能。更多还原

【Abstract】 Routing and Wavelength Assignment (RWA) is an important issue in opticalnetwork. That denote when call request accrue between a source node and destinationnode, how to routing for two nodes and assign the appropriate wavelength. A goodRWA can greatly improve network’s performance. e.g. balance network’s traffic andimprove the blocking probability. But many RWA is basing on ideal network thatignore physical impairment. This assumption has many faults. The RWA of this paperbase on real network that consider some physical impairment. Although this assumptionis less-than perfect, it is of practical significanceTo give a better solution for RWA, the paper propose a Routing and WavelengthAssignment base on Delay&Buffer with Impairment Aware (DB_IA_RWA). The algorithm assumes the PMD and ASE as major loss. If network failed to find asuitable lightpath for the call request, we can buffer the call request in the subqueue.After delaying some time, network layer will look for available lightpath again. Ifthe waiting time reaches the threshold, the CRwould be removed from the subqueue,a call blocking. The algorithm is a hierarchical graph-based model which can resolverouting and wavelength assignment simultaneously. In the absence of wavelengthconverter, new algorithm can dynamically adjust routing strategy to reasonably assignresource. Finally, simulation result show that this algorithm can effectively reduceblocking probability.The main content of the paper includes:(1) Introduce the meaning of studying the RWA problem, and gives the D andG algorithms flowchart.(2) Introduce the network structure, node structure and the topology structurein wavelength routed optical network in detail. Then give the Delay&Buffer flowchart(3) Blocking probability (BP) performance of traditional RWA algorithm in idealnetwork (T_RWA), RWA algorithm in real network(RWA_real) and IA_RWA has beenstudied used OPNET Modeler. Call that has been respectively refused by networklayer and physical layer in RWA_real is recorded.(4) DB_IA_RWA has been simulated used OPNET Modeler. Compared the newalgorithm with other RWA algorithm, this algorithm can improve BP performance.更多还原