光网格计算的节能型业务调度

近年来节能问题成为了光网络研究领域的一个热点问题。基于光网络底层架构的光网格计算的资源由计算资源和通信资源两部分组成。提出了一种基于混合整数线性规划的综合优化这两部分资源能耗的业务调度方法,分析了其节能效果,并分析了业务并行程度与光网格总能耗的关系。     

基于联合备份的服务功能链可靠性保障的部署方法

在网络功能虚拟化(NFV)环境中,针对服务功能链(SFC)部署时的可靠性问题,该文提出对备份虚拟网络功能选择、备份实例放置和服务功能链部署的联合优化方法。首先,定义一个单位开销可靠性提高值的虚拟网络功能衡量标准,改进备份虚拟网络功能选择方法;其次,采用联合备份的方式调整相邻备份实例之间的放置策略,以降低带宽资源开销;最后,将整个服务功能链可靠性保障的部署问题构建成整数线性规划模型,并提出一种基于最短路径的启发式算法,克服整数线性规划求解的复杂性。仿真结果表明,该方法在优先满足网络服务可靠性需求的同时,优化资源配置,提高了请求接受率。     

双链路故障时的共享路径保护

在波长路由光网络中,网络的存活性已经受到越来越多的重视.对单链路故障时的保护已经不能满足某些关键性业务对网络存活性的要求,因而研究了双链路故障时的共享路径保护技术.在动态业务下,将共享路径保护问题归结为整数线性规划.在节点无波长转换能力的情况下,分别提出了为当前业务计算最优路径和固定路径两种策略下的整数线性规划.数值结果表明,相对于专用保护,双链路故障时的共享路径保护能够节约30%左右的波长链路资源.     

一种基于定向扩散的QoS路由算法

提出了一种基于定向扩散的分布式能耗均衡QoS路由选择算法QRDD。QRDD基于路径节点最大最小剩余能量（MaxMPE）和最小跳数（MHC）信息得到梯度,组合利用这两类梯度来得到观测节点和有效传感节点间的多条可选路径,通过多路径路由支持路径的平滑切换,保证性能最优路径被选择,提供失效节点的路径修复和主动通告机制。网络仿真实验表明,QRDD能很好地支持不同业务的资源需求分配,可实现全网能耗均衡。     

无线传感器网络中联合路由优化的高能效链路调度

链路调度技术是提高无线传感器网络数据传输可靠性的重要途径.传统的链路调度算法主要关注如何寻找无干扰传输条件下的最小调度帧,而忽视路径选择对链路调度的影响,会导致部分链路的干扰集过大,降低了时隙复用性.针对这一难题,系统分析了链路调度与路径选择及网络能耗的关系,提出联合路径优化的高能效链路调度模型.为加快求解速度,首先通过变量删减及模型转化,提出基于整数规划的最优路由树构建算法;进一步,根据整数规划求解的路由树与链路需求,提出基于最大干扰度优先的启发式链路调度算法.大量仿真实验验证了本文算法的有效性.     

弹性光网络中基于图着色理论的资源分配算法

传统的波分复用网络采用固定栅格,已无法满足网络需求.提出一种改进的基于图着色理论的路由选择频谱分配(GT-RSA)算法.首先,使用前k条最短路径算法确定备选路由集合,根据各备选路由集合建立备选路由关系图;然后,使用图着色理论的混合整数线性规划模型进行选路,根据分支定界的饱和度最大优先算法得到优解,同时完成频谱的路由着色...     

多基站无线传感器网络中能量高效的基站位置优选算法

结合节能路由算法,研究以最小化网络总能耗为目标的基站位置选择问题.将基站位置候选集为有限集的情形化归为整数线性规划问题,并将候选集为全空间的情形化归为非线性规划问题.由于问题的NP-完全性质,分别针对2种情形设计了相应的启发式算法.通过仿真实验对所提出算法的性能进行验证,结果表明所提算法性能接近最优解.     

基于混合整数线性规划的功率消耗的优化

蜂窝车辆联网(Cellular-Vehicle to Everything，C-V2X)使车与周围的一切物体连通，为车辆用户提供了安全、可靠的服务，选择合适的通信接口能够减少通信设备的功耗。为此，提出基于混合整数线性规划的优化功率消耗策略(Optimizing Power Consumption Strategy Based on Mixed Integer Linear Programming， PC-MILP)，进而通过选择适宜的通信接口，平衡车辆用户与蜂窝设备间功率消耗，先建立目标函数，再利用混合整数线性规划求解器CPLEXMILP求解，进而最小化功率消耗，仿真结果表明，相比于同类的两步能量优化策略(Two-Stage Energy Optimization，TSEO)，提出的PC-MILP模型减少了系统能耗。     

基于粒子群优化的虚拟网络映射算法

本文以提高底层网络资源利用效率为目标,在底层网络不需要支持路径分裂的情况下,建立了虚拟网络映射问题的整数线性规划模型,并提出了一种新的基于粒子群优化的虚拟网络映射算法.该算法以映射开销作为适应度函数,重新对粒子的参数和相关操作进行了定义.模拟实验结果表明,与已有研究成果相比,该算法显著地提高了底层网络长期平均运营收益与...     

联合能耗与负载均衡的虚拟网络映射方法

为解决弹性光网络中虚拟网络映射时能耗严重、资源分配不均的问题,该文提出一种联合能耗与负载均衡的虚拟网络映射（PC-LB-VONE）方法.在虚拟节点映射时,选择相邻链路长度短、光节点计算资源多与相邻链路带宽资源多的光节点映射.在虚拟链路映射时,提出一种基于极大团的候选光路资源匹配度单路径映射策略.当单路径映射失败时,设计基于链路负载均值的多路径映射策略.仿真结果表明,所提方法能在减少弹性光网络能耗的同时均衡网络负载.     

Resource efficient network design and traffic grooming strategy with guaranteed survivability

In WDM networks, path protection has emerged as a widely accepted technique for providing guaranteed survivability of network traffic. However, it requires allocating resources for backup lightpaths, which remain idle under normal fault-free conditions. In this paper, we introduce a new design strategy for survivable network design, which guarantees survivability of all ongoing connections that requires significantly fewer network resources than protection based techniques. In survivable routing, the goal is to find a Route and Wavelength Assignment (RWA) such that the logical topology remains connected for all single link failures. However, even if the logical topology remains connected after any single link fault, it may not have sufficient capacity to support all the requests for data communication, for all single fault scenarios. To address this deficiency, we have proposed two independent but related problem formulations. To handle our first formulation, we have presented an Integer Linear Program (ILP) that augments the concept of survivable routing by allowing rerouting of sub-wavelength traffic carried on each lightpath and finding an RWA that maximizes the amount of traffic that can be supported by the network in the presence of any single link failure. To handle our second formulation, we have proposed a new design approach that integrates the topology design and the RWA in such a way that the resulting logical topology is able to handle the entire set of traffic requests after any single link failure. For the second problem, we have first presented an ILP formulation for optimally designing a survivable logical topology, and then proposed a heuristic for larger networks. Experimental results demonstrate that this new approach is able to provide guaranteed bandwidth, and is much more efficient in terms of resource utilization, compared to both dedicated and shared path protection schemes.     

IP over WDM网络最小功耗模型和休眠机制研究

针对IP over WDM网络,建立了整数线性规划(ILP)最小功耗模型,计算了满足峰值业务需要开启的设备数目;对于低峰业务提出休眠机制,分别利用最小光路数算法与最小跳数算法,在保证连接无阻塞的情况下找出空闲设备,对比峰值业务得到不同算法下的设备使用率,确定IP over WDM网络的节能潜力。结果表明,ILP优化模型的网络功耗最小,最小光路数算法次之;低峰业务下利用休眠机制可以关闭设备的比例占40%～60%;采用最小光路数算法的休眠机制节能效果较优。     

Shared Risk Link Group (SRLG)-Diverse Path Provisioning Under Hybrid Service Level Agreements in Wavelength-Routed Optical Mesh Networks

The static provisioning problem in wavelength-routed optical networks has been studied for many years. However, service providers are still facing the challenges arising from the special requirements for provisioning services at the optical layer. In this paper, we incorporate some realistic constraints into the static provisioning problem, and formulate it under different network resource availability conditions. We consider three classes of shared risk link group (SRLG)-diverse path protection schemes: dedicated, shared, and unprotected. We associate with each connection request a lightpath length constraint and a revenue value. When the network resources are not sufficient to accommodate all the connection requests, the static provisioning problem is formulated as a revenue maximization problem, whose objective is maximizing the total revenue value. When the network has sufficient resources, the problem becomes a capacity minimization problem with the objective of minimizing the number of used wavelength-links. We provide integer linear programming (ILP) formulations for these problems. Because solving these ILP problems is extremely time consuming, we propose a tabu search heuristic to solve these problems within a reasonable amount of time. We also develop a rerouting optimization heuristic, which is based on previous work. Experimental results are presented to compare the solutions obtained by the tabu search heuristic and the rerouting optimization heuristic. For both problems, the tabu search heuristic outperforms the rerouting optimization heuristic.     

Efficient Protection in MPλS Networks Using Backup Trees: Part One—Concepts and Heuristics

Multi-protocol lambda switching (MPS) has recently been applied in the optical network control plane to provide fast lightpath provisioning. As an increasing amount of traffic is carried in optical transport networks (OTNs), single network failures can affect a vast amount of traffic, making lightpath protection crucial. Therefore, shared backup tree (BT) lightpath protection is a promising paradigm in MPS networks due to its ability of fast recovery and its efficiency in consumed resources. A shared BT is used to protect a group of working lightpaths towards the same destination. From the working lightpaths in such a group, only one affected lightpath at a time can be recovered using the BT. The main problem is how to group and route the working paths (WPs) and how to route the BTs, in such a way that the capacity resources used by the WPs and the BTs are minimized. In Part One of this study (presented in this paper), we propose three approaches to cope with this problem. The first approach is a purely integer linear programming (ILP) based method. The second one is a combination of ILP and a heuristic technique. The last one is a purely heuristic approach. In this paper, these approaches are theoretically compared. In Part Two [1] of this study, several simulations are carried out in order to compare these approaches in terms of performance and computing effort. The experimental results are in line with the theoretical expectations.     

面向节点异构的能耗感知虚拟网络映射算法

在底层网络节点异构的环境中,能耗优化的虚拟网络映射问题并不是最小化工作节点和链路数。该文针对此问题,构建底层网络节点和链路的负载能耗模型,并以能耗最优为目标,建立虚拟网络映射问题的数学模型,提出一种能耗感知虚拟网络映射算法。该算法在节点映射阶段以最小化能耗和协调链路映射为原则,将虚拟节点映射至综合资源能力最大的底层节点上,并采用改进的能耗感知k最短路径法进行链路映射。仿真结果表明,该算法显著减少虚拟网络映射的能耗,且底层网络节点异构性越大,能耗优势更为明显。     

Dimensioning optical networks under traffic growth models

In this paper, we consider the problem of dimensioning a large optical wavelength-division multiplexing (WDM) network assuming the traffic is growing over time. Traffic between pairs of nodes is carried through lightpaths which are high-bandwidth end-to-end circuits, occupying a wavelength on each link of the path between two nodes. We are interested in dimensioning the WDM links so that the first lightpath request rejection will occur, with high probability, after a specified period of time T. Here we introduce the concept of capacity exhaustion probability - the probability that at least one lightpath request will be rejected in the time period (0,T) due to lack of bandwidth/capacity on some link. We propose a network dimensioning method based on a traffic growth model which eventually results in a nonlinear optimization problem with cost minimization as the objective and route capacity exhaustion probabilities as the constraints. Computation of exact capacity exhaustion probabilities requires large computing resources and is thus feasible only for small networks. We consider a reduced load approximation for estimating capacity exhaustion probabilities of a wavelength routed network with arbitrary topology and traffic patterns. We show that the estimates are quite accurate and converge to the correct values under a limiting regime in the desired range of low-capacity exhaustion probabilities.     

Green optical backbone networks: virtual topology adaptation using a page rank‐based rating system

An energy‐aware virtual topology rating system is proposed in this work, which can be utilized as a tool during the virtual topology reconfiguration procedure in an optical backbone network in order to reduce its energy consumption. It is well known that maintaining a static virtual topology in Internet Protocol (IP)‐over‐Wavelength Division Multiplexing (WDM) networks is not energy‐efficient. To that end, virtual topology adaptation algorithms have been developed to adjust the virtual topology to the constantly fluctuating traffic load. While these algorithms achieve significant energy savings, further reduction on the total network energy consumption can be achieved through the proposed rating system. The proposed rating system is a modified version of the page rank algorithm, which ranks websites in the Internet based on their importance. The proposed rating system attributes ratings to lightpaths, which indicate the relative significance of a lightpath in the virtual topology in terms of energy consumption. The rating can be used during the routing procedure as an energy efficiency indicator, in order to increase the number of lightpaths that are deactivated from the reconfiguration mechanism and increase the utilization per lightpath. The proposed reconfiguration scheme (page rank‐based virtual topology reconfiguration) achieves up to 12% additional energy savings in comparison to an existing virtual topology reconfiguration algorithm at the cost of slightly increased average hop distance. Copyright © 2015 John Wiley & Sons, Ltd.     

无线传感器网络中基于链路质量的路径延时分析

基于链路质量给出了路径满足实时性概率的上界,并证明了计算其上界的时间复杂度为指数级。另外在考虑链路质量的基础上,提出了一种在给定的延迟阈值下最大化端到端数据分组发送成功概率的贪心算法(RROP)。根据给定的延迟阈值和链路质量,RROP算法通过设置每跳链路的最大重传次数来优化端到端数据分组发送成功的概率。证明该算法能够在多项式时间内找到最优解并且通过该最优解获得路径满足实时性概率的一个近似最优的下界。实验结果表明给出的路径延迟分析上界和下界是准确的,并且提出的RROP算法在节省能量和满足实时性上比传统的方法能够获得高出10%以上的性能。     

物联网感知层多路径传输策略研究

多路径数据传输是无线传感器网络亟需解决的一个关键问题.本文针对节点故障、链路失效和外界干扰影响网络稳定性和可靠性,提出一种基于混合蛙跳算法的无线传感器网络多路径传输策略.首先我们详细介绍了蛙跳算法及其原理,之后我们将其应用到无线传感器网络多路径传输策略之中,接着运用混合蛙跳算法对传感网络节点其进行更新、划分、重组以便选择出最优节点建立传输最优路径,提高网络的稳定性和可靠性.通过算法仿真与结果对比提出的算法与AODV、粒子群PSO算法相比,在网络能耗、传输时延、丢包率、连通率和可靠度等方面都具有较好的性能.其中网络能耗比AODV、PSO算法降低了62.5％和35.8％.     

具有路径能耗优化特性的WSN无标度容错拓扑控制算法

针对数据传输型的大规模无线传感网络中路径能量损耗问题,建立在多跳模式下的网络路径能耗优化模型,得出可以使网络通信能耗最小的节点度取值规律。依据节点度的最优取值,通过控制网络平均节点度的适应度模型来构建网络拓扑,提出一种具有路径能耗优化特性的无标度容错拓扑控制算法EETA(energy efficiency topology algorithm)。动态性能分析表明,由该算法生成的网络拓扑,其节点的度分布服从幂律,具有无标度拓扑的强容错能力。仿真实验结果显示,该算法同时也降低了网络路径能量消耗,具有路径节能性。