可生存LR-PON中基于连接可用性的成本有效规划方法(英文)

聚焦长距离无源光网络生存性机制研究,针对单共享风险链路组故障提出一种基于连接可用性的成本有效规划方法.首先,设计了一种基于故障概率的连接可用性模型,计算每个光网络单元的连接可用性.对于不满足连接可用性要求的每个工作光网络单元,为其分配备用光网络单元,其中每个备用光网络单元需要为工作光网络单元预留备用容量.然后,在不同光网络单元之间部署备用光纤,确保每对工作和备用光网络单元之间至少存在一条备用光路径.当一个工作光网络单元因为光纤链路故障而遭遇连接中断时,可将其业务通过备用光路径转移到备用光网络单元承载.通过仿真对所提方法在备用光纤部署成本方面的性能进行了分析.结果表明,该方法能实现比传统邻居保护方法更低的备用光纤部署成本,可解决备用容量分配和备用光纤部署的联合优化问题,在满足连接可用性要求的前提下,通过最小的备用光纤部署成本实现所有业务完全保护.     

基于SRLG不相关的共享保护算法的研究

通过对共享保护算法的深入分析,使用K条最短路和迭代思想的方法,提出了两种共享风险链路组不相关的共享保护算法,并在仿真平台上对两种算法的性能进行了仿真.KWFF算法借鉴了传统的K条最短路策略,并且在每一个波长平面上,都对新到业务进行了K条工作路由的计算,极大挖掘了网络中潜在的波长资源.而IFF算法由于引入了迭代的思想,避免了共享风险链路组问题中,所特别有“陷阱”问题的出现,并且利用两套权重计算公式,在计算工作路由和保护路由的时候,充分考虑了网络资源的实时变化情况.通过仿真数据可以看到,与以往算法相比,KWFF和IFF算法大大降低了网络阻塞率,并且提高了网络资源的使用效率.     

基于SRLG约束和资源共享的交迭段保护机制研究

通过对共享风险链路组约束机制和交迭段保护机制的分析,将两者相结合并根据工作和保护路径分别采用动态链路权重调整,提出了一种基于共享风险链路组不相关的交迭段共享保护算法.交迭段共享保护算法在共享风险链路组不相关的约束条件下,为整个工作路由提供了多个交迭的保护段,并给出了一种能够合理有效选择这些交迭保护段的方法.对交迭段共享保护算法的分析和仿真结果表明,与以往保护算法相比,交迭段共享保护算法不但大大提高了网络连接的可靠性,而且还通过不同交迭保护段间资源的合理共享,有效地提高了网络资源的利用率.     

WDM光网络故障的快速共享恢复方案

在网络恢复仿真实验中发现当WDM光网络中的工作通路的链路数目为2或3时, 通路恢复资源能得到较大程度的共享. 在此基础之上, 提出了一种新的WDM光网络故障的恢复方案-分段共享恢复方案(SSR). 与现有的基于通路共享恢复方案(PSR)相比, SSR的恢复时间大大下降, 同时又基本上保持了PSR高效的资源利用率. 阐述了SSR的分段规则和实现过程, 并对SSR的性能进行了理论分析和计算机仿真.     

智能电网的PTN线性保护机制研究

智能电网信息化、数字化的发展需求,促使电力通信向IP化的方向发展,使得适合IP业务的分组传送网络技术PTN逐步得到了应用。ITU-T定义的G.8131 PTN线性保护技术可用来保护电网通信业务。为缩短链路故障时N对线性保护同时切换的业务恢复时间,对线性保护实现机制进行研究,提出了倒换操作优先执行的方案。通过理论分析和实验验证,链路故障时N对保护组同时倒换的性能近似O(1),较好的满足了线性保护50ms故障恢复性能,可更好的保障智能电网通信系统的生存性。     

智能光网络中一种新型的分布式恢复方法

提出了一种基于固定备用路由和目的端触发的智能光网络中的分布式恢复方法,所选择的任一对源端节点和目的的端节点之间的固定备用路由包括该节点对之间的k条最短路径路由和基于部分链路无关的路由.目的端节点一旦探测到业务通道的失效将立即启动恢复进程,根据网络当前的资源使用情况,在这些备用路由中按照一定的次序选择一条恢复路由并为此分配一条可用的波长(对于没有波长变换器的光网络),然后将恢复通道的建立请求消息发送给该恢复通道的相关节点,这些相关节点可以锁定相关的网络资源,以避免来自其他恢复通道的竞争.所提出的算法增加了固定备用路由的数量,从仿真结果可以看出,该方法明显改善了失效连接的阻塞性能.     

IP over WDM网络中可恢复的路由选择策略与算法

研究了IP over WDM网络中各层备用资源的分配问题,提出了一种新的IP over WDM网络中可恢复的路由选择策略以及应用于其中的备用路由选择算法.该策略通过层间备用资源共享,能够完全利用网络中为恢复光层故障所预留的资源来进行IP层故障恢复,从而大大提高了网络的资源利用率.对所提出的策略进行了性能分析,并给出了相应的性能指标.     

最小代价最大节点度数的稀疏光疏导方法

疏导可以增加多播业务请求成功传输概率并提高光纤链路带宽利用率,但波分复用光网络中所有节点具有疏导能力则会增加网络造价和复杂度.本文研究了稀疏疏导网络中疏导节点选择策略,提出基于最小代价最大节点度数的疏导节点选择策略;根据疏导节点和非疏导节点功能差别,改进了稀疏疏导网络中多播请求的疏导传输方法.结合最小代价最大度数疏导节点选择策略和多播业务稀疏疏导传输方法,提出一种根据网络业务阻塞率限定值指标实现多播请求所需最少数目疏导节点的稀疏路由方法.仿真结果表明:在网络给定波长数和光收发器端口数目情况下,所提策略能够节约所需疏导节点数目并优化疏导节点位置,降低网络节点构造造价.     

基于光开关和图论的多主体协作光纤传感网络自修复方法研究

针对多主体协作健康监测系统中光纤传感网络链路故障,提出了一种基于光开关和图论的光纤传感网络自修复方法。研究采用图论相关理论表述含光开关光纤传感器网络链路的连通情况,据此研究了光纤传感网络出现链路故障时光开关的切换策略,实现对失效光纤布拉格光栅(FBG)传感器信号的自修复。以航空铝板结构试验件为实验对象,针对光纤传感网络典型链路故障,对基于光开关和多主体协作的光纤传感网络自修复效果进行了对比实验。实验结果表明:在光开关和主体协作下,识别精度较没有修复时识别精度提高10.02mm,仅比网络结构完好时识别精度降低3.61mm,有效提高了载荷识别精度以及光纤传感网络的可靠性。     

一种新的格状波分复用光网络保护方法

在P圈法和哈密顿环保护法的基础上,提出了一种新的适用于格状波分复用光网络的基于资源的环保护方法,我们称之为RP圈法.与其他基于环的格状光网络保护方法相比,RP圈法具有配置方式简单、与业务模型不相关以及圈具有长度限制等许多特点.文中给出了RP圈法的一种启发式算法,仿真结果表明此算法具有较高的容量效率,是一种可适用于动态业务的实用化光网络保护方法.     

Deep Q-learning based optimal resource allocation method for energy harvested cognitive radio networks

In this article, we propose a deep Q-learning based algorithm for optimal resource allocation in energy harvested cognitive radio networks (EH-CRN). In EH-CRN, channel resources of primary users (PU) networks are shared with secondary users (SU) and energy harvesting allows nodes of the CRN to acquire energy from the environment for operation sustainability. However, amount of energy harvested from the environment is not fixed and requires dynamic allocation of resources for obtaining optimum network and throughput capacity. In this work, we overcome the limitations of existing Q-learning based resource allocation schemes which are constrained by large state-space systems and have slow convergence. Proposed deep Q-learning based algorithm improves the resource allocation in EH-CRN, while considering quality of service (QoS), energy and interference constraints. Simulation results show that proposed algorithm provide improved convergence and better resource utilization compared to other techniques in literature.     

A novel hop constrained sub-path protection routing algorithm in WDM networks

The survivable design is a key issue in reliable WDM optical networks to assure the service guarantee to customers. The sub-path protection metrics can achieve shorter failure recovery time than path protection metrics for a modest sacrifice in resource utilization. Rather than the conventional equal-length sub-path protection metrics (CDR algorithm), in this paper we propose a novel heuristic dynamic hop constrained sub-path protection (HCSPP) routing algorithm to provide a more flexible way to compute the primary sub-paths and the backup sub-paths. The main idea of HCSPP is that we first compute the primary path and its end-to-end backup path, the found primary and its end-to-end backup path constitute a protection cycle, then we partition the protection cycle into several smaller protection cycles by the straddling paths we introduced, the hop count for each small protection cycle should be constrained in a threshold value and the value can be adjusted according to different network topologies or different management policy, thus we can control the tradeoff between the failure recovery time and the resource utilization ratio. Compared with the CDR [P.-H. Ho, J. Tapolcai, T. Cinkler, IEEE/ACM Trans. Networking 12 (6) (2004) 1105] algorithm, HCSPP can achieve a better compromise between the blocking probability and the failure recovery time. We evaluate the effectiveness of the HCSPP and the results are found to be promising.     

Double-link failure protection algorithm for shared sub-path in survivable WDM mesh networks

We propose a novel shared sub-path protection (SSPP) algorithm to protect the double-link failures in wavelength division multiplexing (WDM) mesh networks. SSPP segments the primary path into several equal-length sub-paths and searches two link-disjoint backup paths for each sub-path. When computing the paths, SSPP considers the load balance and the resource sharing degree, so that the blocking ratio can be effectively reduced. The simulation results show that SSPP not only can completely protect the double-link failures but also can make the tradeoffs between the resource utilization ratio (or blocking ratio) and the protection-switching time.     

Performance analysis of dedicated protection and shared protection for waveband switching based on multi-granularity optical cross-connect

In order to save the switching ports and the cost of Multi-Granularity Optical Cross-Connect (MG-OXC), the waveband switching technique was proposed to groom multiple wavelength-level traffic to a few waveband tunnels to be switched by a few switching ports in MG-OXC. At the same time, protection for fibers is very important to ensure the service continuity since each wavelength carries a lot of traffic. Although existing works have addressed the waveband switching protection, most of them separately considered only the dedicated protection or shared protection in static demand scenario and did not deeply analyze and compare the dedicated protection and shared protection in dynamic demand scenario. Therefore, in this paper, we deeply study the consumptions of wavelengths in fibers and ports in MG-OXCs for Waveband Shared Protection (WSP) and Waveband Dedicated Protection (WDP) in dynamic demand scenario, and propose the port-cost calculation and update methods based on a new waveband layered auxiliary graph that is developed based on MG-OXC structure. In simulations, we compare WSP, WDP, traditional end-to-end waveband shared protection and traditional end-to-end waveband dedicated protection. Simulation results show that the shared protection has smaller port-cost, better wavelength utilization efficiency and lower blocking probability than the dedicated protection with the same waveband switching policy, and the sub-path waveband switching has bigger port-cost, better wavelength utilization efficiency and lower blocking probability than the end-to-end waveband switching with the same backup wavelength assignment policy.     

Provisioning for restorable WDM optical networks

Restoration is a very critical issue in WDM optical networks. Provisioning also plays a great role in the networks because it deals with resource allocation. In this paper, we have presented two provisioning strategies for restorable networks: unity link weight strategy and varying link weight strategy. The strategies are implemented for critical applications which require 100% degree of survivability. The simulation is done using different proportionate of resources for working and restoration lightpaths. The simulated results show that the performance of the unity link weight strategy is much better than the varying link weight strategy in terms of resource requirement and blocking probability.     

适用于多粒度光网络的共享保护算法及其分析

结合多粒度光网络自身特点提出了两种适用于多粒度光网络中的共享保护算法,它们分别基于波带粒度和基于波长粒度对光层连接提供保护.仿真结果显示,提出的算法性能优于以往的专用保护算法,通过对仿真结果的分析,得出了网络参量变化对各个算法的影响.     

A DEC-MDP model for joint uplink/downlink resource management in OFDMA-based networks

With the advent of mobile services with asymmetric and symmetric quality of service (QoS) requirements, traditional single link resource allocation techniques have started to show some limitations in handling the complex requirements. To address these issues, joint uplink/downlink resource management approaches were recently introduced where both communications links are jointly considered in the resource management process. One direct consequence of this coupling is a modification of the underlying queueing behavior since the decision making process in one direction in terms of transmission rate now depends on the performance achieved in the opposite direction. In this paper, we present a modeling approach of the decision making process that takes place under the joint uplink/downlink resource management framework. Using decentralized Markov decision processes (DEC-MDP) as a model and gradient ascent methods as an optimization technique, we formulate and solve the joint uplink/downlink decision making process. The uplink and downlink of each user are considered as agents. Assuming certain subcarrier and power allocation schemes, we investigate the resource usage in the uplink and downlink to achieve a certain delay balancing constraint where the total delay in the uplink and downlink is bound by a pre-determined threshold. The approach followed starts by modeling the problem in hand using DEC-MDPs. After discussing the different aspects of the model, the solution using gradient ascent is described. Simulation results illustrate the different dimensions of the problem and their impact on the resource management process.     

适用于多粒度光网络的共享保护算法及其分析

结合多粒度光网络自身特点提出了两种适用于多粒度光网络中的共享保护算法,它们分别基于波带粒度和基于波长粒度对光层连接提供保护.仿真结果显示,提出的算法性能优于以往的专用保护算法,通过对仿真结果的分析,得出了网络参量变化对各个算法的影响.