WDM光网络保护中一种新的波长预留方法

研究了WDM网状网中双链路失效的保护设计问题,在双链路失效保护时采用"裁剪相继最短路"算法计算工作通路和保护通路,而预留波长时利用波长预留矩阵预留资源,并进行仿真实验.实验结果表明,基于BRM的波长预留方法与已有的两步计算法相比大大减少预留资源.     

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。     

用于光数据网络的波长路由协议

介绍Cisco提出的波长路由协议（WaRP)及其保护恢复方案。WaRP弥补了多协议标签交换（MPLS）协议缺乏网络拓朴分配及业务保护恢复的缺陷，直接在光层上进行业务的保护恢复，并提出四种业务等级类型以满足不同QoS业务的要求，可以预见，未来光数据网络的控制平面将由MPLS和WaRP共同构建。     

扩展资源预留协议的波长选择设计方案分析

主要研究基于路径计算单元( PCE)的波长交换光网络(WSON)中的波长分配问题.提出了PAWA(PCF Assistant Wavelength Assignment)方案,在可能发生冲突的path请求上做标记,来帮助目的节点选择波长,从而避免资源冲突.最后利用离散事件模拟工具OMNeT++进行了仿真分析,相比首次命中(FF)和随机命中(RF),PAWA方案扩展了信令,降低了阻塞率,并没有增加建路延时和资源利用率.     

波长交换光网络中路由波长分配技术

路由波长分配问题是在给定连接的情况下,为该请求分配适当的光路进行传输。在无波长转换能力的情况下,需要为光路在其传输的链路上分配相同的波长,这就是波长连续性问题。物理层的光损伤极大的限制了光网络的能力,因此需要可感知损伤的路由波长分配算法来保证传输的质量。对于不同的感知损伤的路由波长分配方式,相应地,有不同的控制平面结构。     

基于波长路由的卫星光网络研究

为实现卫星通信的突破性发展,扩大卫星通信容量和带宽,建立了新型的卫星网络模型,分析了卫星光网络的技术难点问题,利用副载波和光波的双层路由方案,进一步提出了卫星光网络的新思路和实现方案.     

波长路由光网络中RWA算法的设计分析

文章通过对波长路由光网络中路由与波长分配(RWA)问题的研究,介绍了求解路由子问题和波长分配子问题的常用方法,总结了3种类型的RWA问题的优化解决方法,最后对目前RWA算法设计中存在的问题进行了分析并阐述了解决此类问题的重要性.     

刍议自动交换光网络的路由协议

自动交换光网络最大的特点就是以传送平面、管理平面为基础,引入智能控制平面技术,并且通过信令技术、路由技术以及自动发现技术,提高了光层资源控制的灵活性,同时也提高了网络的可扩展性与可用性,并且网络结构得到进一步简化,降低了运营成本。由此可见,自动交换光网络是未来的发展趋势。本文主要针对自动交换光网络的路由协议展开讨论,首先阐述其基本概念,然后对三种路由模式进行分析,最后介绍几种路由协议。     

智能光网络中的路由和波长分配问题

随着下一代智能光网络概念的提出，应用于传统光网络的路由和波长分配方法面临着许多新的挑战。本以自动交换光网络为代表，分析了智能光网络中不同类型连接的特点和实现路由和波长分配的控制软件模块，并着重从路由模式、多粒度分层选路、路由和波长分配算法、信令路由协议等几个方面出发，对智能光网络中的路由和波长分配问题进行了深入的探讨。同时提出了相应的解决方案。     

具有容错能力的波长路由光网络的拓扑设计

研究了具有容错能力的波长路由光网络的拓扑设计问题.提出了一种基于业务流的初始物理拓扑产生算法,与随机拓扑生成算法相比,该算法产生的物理拓扑更接近于最优拓扑.另外,还提出了一种新的链路拥塞计算方法,它能够更好地反应链路的实际状态.数值结果显示文章提出的物理拓扑设计策略具有更快的收敛速度.     

An experimental switching-aware GMPLS-based lightpath provisioning protocol in wavelength-routed networks

In wavelength-routed optical networks, the high-delay introduced by the optical switching fabric for resource reservation increases critically the lightpath setup delay. In order to minimize the setup delay, Generalized Multi-protocol Label Switching (GMPLS) introduced the concept of Suggested Label Object (SL), which allows to start reserving and configuring the hardware with a proposed wavelength from the source node to the destination node. This solution is not optimal in wavelength selective networks (WSN) (i.e., without wavelengths converters). The need of guaranteeing the wavelength continuity constraint for end-to-end optical connections, combined with the lack of global wavelength-based link information (the source node is not aware of which wavelengths are available on each link), makes that the likelihood of establishing a lightpath using the proposed suggested label may be minimum. In this article, we propose an enhancement to the current GMPLS RSVP-TE signaling protocol with offset time-based provisioning that minimizes the lightpath setup, improving the overall network performance in terms of blocking probability and setup delay. Experimental performance evaluation has been carried out in ADRENALINE testbed, a GMPLS-based intelligent all-optical transport network.     

全光网中基于跳数的波长分配算法

在有波长连续性限制的情况下,减少波长预留冲突需要在波长预留时尽量使用不同的波长,这使全网的空闲波长数减少,容易导致大跳数光路的连接请求失败。解决波长预留冲突问题的大多数算法都把解决问题的目标设为降低网络阻塞率,无法兼顾网络中大跳数光路的情况。本文提出了用于全光网中基于跳数的波长分配算法,该算法通过建立跳数与波长之间的相互对应关系,对未来可能发生预留冲突的光路及其要预留的波长进行预测,根据预测尽量使用相同波长,增加全网的空闲波长数。在解决波长预留冲突问题的同时,实现支持大跳数光路连接请求的目标。     

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.     

A synchronous duty-cycled reservation based MAC protocol for underwater wireless sensor networks

To design an energy-efficient Medium Access Control (MAC) protocol for the Underwater Wireless Sensor Networks (UWSNs) is an urgent research issue since depleted batteries cannot be recharged or replaced in the underwater environment. Moreover, the underwater acoustic channels are affected by hindrances such as long propagation delay and limited bandwidth, which appear in the design of the MAC protocol for the UWSNs. The available MAC protocols for the terrestrial wireless sensor networks exhibit low performance in energy efficiency, throughput and reliability in the UWSNs, and cannot be used in the UWSNs directly because of their unique characteristics. This paper proposes a synchronous duty-cycled reservation-based MAC protocol named Ordered Contention MAC (OCMAC) protocol. The basic mechanism of this protocol is to schedule data transmission by transmitters through the scheduling of Ready To Send (RTS) frames. The protocol eliminates the possible collision during data transmission and improves communication efficiency. The paper analyzes the performance in energy efficiency, throughput and reliability of the protocol by modeling the queuing behavior of OCMAC with a Markov Chain process. Furthermore, the analytical model is validated through a simulation study. The analysis results demonstrated that while providing good throughput and reliability, OCMAC can achieve energy saving.     

星形波长路由光网络中的波长分配

文章主要研究了网络中心与其它节点之间由两条光纤成双向传输链路的情况，给出了均匀和顾机两种业务条件下网络中所需波长数的理论下限范围，利用图着色理论构造启发式算法解决了星形网络中的波长分配问题，最后通过实际波长分配验证了算法的有效性。     

分布式无线传感器网络通信协议研究

在归纳分布式无线传感器网络研究进展的基础上，给出了综合分布式无线传感器网络技术各个方面的协议体系结构，并在新的体系结构下，系统地阐述了分布式无线传感器网络通信协议研究的进展，介绍了典型的应用案例和国外相关计划的研究情况。最后，指明了这一处于发展初期的研究领域的未来发展方向。     

时间依赖的混合型网络的分布式路由协议

提出了时间依赖的混合型网络模型(HTDN 模型),有效地描述了网络中链路权值随时间变化的特性,并且网络中的节点可以采用不同的等待策略;并给出了 HTDN 模型的路径优化理论。在此基础上设计了有效的分布式路由协议 DMDRP,能计算出 HTDN 模型中所有节点对之间的最短延时路径,并证明了协议的正确性。最后通过仿真试验,给出了 DMDRP 协议与传统路由方案的性能对比分析。