WDM网络中支持优先级的波长分配算法

本文提出了一种在WDM网络中支持优先级的波长分配算法,通过计算相对容量损失,力图在对较高优先级光路建立请求进行波长分配时,找到对较优先级请求影响最小的波长分配方案,这样,该算法既保证了较高优先级光路建立请求具有较低的阻塞率,同时又对较低优先级请求进行了优化,从而改善了全网的平均阻塞率。文中给出了计算机仿真结果。     

多域光网络中基于优先级的波长路由分配算法

本文提出一种在多域光网络中基于优先级的路由波长分配算法.算法设计旨在解决复杂网络拓扑下,多任务请求路由波长分配问题.本文首先根据复杂网络拓扑情况与任务请求状况,完成多域的划分,对跨域任务的最短路由进行路由分裂;其次依据域内与域间优先级设定策略,完成多任务请求优先级设定;按照优先级顺序,采用模糊优化波长分配算法完成波长分配.仿真结果表明本算法在处理复杂网络拓扑、多任务路由波长分配问题上效果明显,有效的降低了网络请求阻塞率,提高了光网络资源利用率.     

WDM光传送网中支持优先级的波长分配算法

文中提出了一种用于WDM光传送网的支持优先级的波长分配算法－动态门限法,该算法保证了较高优先级的光路建立请求具有较低的阻塞率,同时又考虑到较低优先级的光路建立请求的性能优化,从而很好地降低了全网的平均阻塞率。文中给出了计算机仿结果。     

一种公平的多优先级WDM光网络波长分配算法

文章研究了波分复用(WDM)光网络中动态业务下的波长分配问题,在无波长转换器的条件下,提出了一种加入了公平性考虑的动态门限算法.该算法在支持多优先级的动态门限法的基础上,通过更新初始优先级减少了不同距离光路连接请求间的阻塞率差别,改善了公平性.计算机仿真结果说明了该算法的有效性.     

基于相对容量损失的一种改进波长寻路算法

本文提出一种改进的基于相对容量损失（RCL）最小的波长分配和路由选择算法-DPRCL算法.该算法通过发送探测报文得到光路容量损失率,从而选择具有最小光路容量损失率的波长和路由建立连接.在不牺牲阻塞性能的情况下,DPRCL大大减小了实现复杂度以及网络开销,并适用于采用分布式控制的自适应路由的网络环境,而不限于RCL的固定路由方式.     

WDM 网络中基于优先级的多任务波长路由分配算法

提出了一种在WDM网络中基于优先级的多任务波长路由分配算法。算法设计旨在提高光网络资源的利用率、降低网络请求阻塞率。分析了任务请求的路由类型以及负载容量对请求优先级划分的影响方式,给出了网络请求优先级划分策略,结合网络的实时状态提出了一种基于优先级的多任务波长路由分配算法。仿真结果表明,该算法相比现有算法降低了网络请求阻塞率,提高了资源利用率。     

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。     

WDM网络中基于阻塞公平性的业务疏导和波长分配

在具有多速率级别连接请求的WDM网络中，通过为较高速率的请求预留更多的波长集合，结合网络节点对较低速率业务更强的输导能力，解决网络的阻塞公平性和全网的流量问题。在中国教育科研网的仿真实验，本文的策略比First-fit算法取得了更好的阻塞公平性能，并接纳了更多的网络流量。当负载为170Erlang时，多接纳的流量约为12％。     

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。     

WDM光网络中一种备用路由下支持优先级的波长分配算法

研究了WDM光网络中的动态业务下的波长分配问题,在无波长转换器的条件下提出了一种改进的动态门限算法.该算法不仅能保证高优先级请求有较低的阻塞率,同时还能优化低优先级请求的阻塞率,从而改善全网的平均阻塞率.此外,该算法利用负载均衡算法,能更加精确地描述波长分配对全网状态的影响,从而更加有效地利用了网络资源.计算机仿真结果证明了该算法的有效性.     

固定选路的波分复用全光网中的波长分配算法

该文研究了动态业务下,无波长变换的波分复用光传送网采用固定选路时的波长分配问题,提出了一种中心式的波长分配算法-最小影响算法。该算法能精确地描述某个波长的分配对全网状态的影响,因而能够更有效地使用网络资源。计算机仿真表明,如果用阻塞概率来衡量,该波长分配算法优于文献中已有的典型算法。     

WDM网络中的一种波长分配算法

本文研究了动态业务下，采用固定选路和备用选路的波分复用光传送网中的波长分配问题，提出了一种波长分配算法-相对最小影响算法。与己朋的利用全网信息分配波长的算法相比，该算法能更精确地描述波长分配对全网状态的影响，使网络资源的充分利用成为可能。计算机仿真表明，该波长分配算法性能较好。     

Adaptive wavelength routing in all-optical networks

We consider routing and wavelength assignment in wavelength-routed all-optical networks (WAN) with circuit switching. The conventional approaches to address this issue consider the two aspects of the problem disjointly by first finding a route from a predetermined set of candidate paths and then searching for an appropriate wavelength assignment. We adopt a more general approach in which we consider all paths between a source-destination (s-d) pair and incorporate network state information into the routing decision. This approach performs routing and wavelength assignment jointly and adaptively, and outperforms fixed routing techniques. We present adaptive routing and wavelength assignment algorithms and evaluate their blocking performance. We obtain an analytical technique to compute approximate blocking probabilities for networks employing fixed and alternate routing. The analysis can also accommodate networks with multiple fibers per link. The blocking performance of the proposed adaptive routing algorithms are compared along with their computational complexity     

Dynamic Routing and Wavelength Assignment Using Cost Based Heuristics in WDM Optical Networks

Dynamic routing and wavelength assignment problem in optical networks is a two-step problem that is influenced by the choice of a successful optimal path selection and wavelength assignment. Proper selection techniques reduce the number of wavelengths required in the network and thereby improves traffic grooming. Heuristic algorithms and integer linear programming models help in selection of route and wavelength separately. Hence, the computation time is large which makes the system slow. A cost function is computed which uses independent parameters in the network for the selection of route and wavelength for a call. The heuristic reduces computation time by combining the search of route and wavelength to be assigned. In addition, the network performance is analyzed with and without alternate routing along with proposed heuristics. The selection of proper route and wavelength finding technique is very essential since it improves the grooming factor of the network thereby allowing more traffic support by the network. Our objective is to investigate and propose a cost based heuristics for dynamic traffic routing and wavelength Assignment in WDM optical networks. For this we plan to develop cost functions and heuristics to compute the route and wavelength assignment strategy. Here, our objective is to reduce the computation time for selection of route and wavelength assignment strategy by weighted cost function. The function has to include network parameters for its processing. Our work provides an overview about DRWA by applying cost based heuristics in WDM networks. This paper explains the proposed cost function and its applications in line with selection of independent parameters. The details of other functions like cost function formulation, hop-based route assignment, available wavelength based route assignment, mathematical analysis of proposed cost function are also explained. Results and discussions based on the findings are presented.

     

Priority-based offline wavelength assignment in OBS networks

Optical burst switching (OBS) is a promising technique for wavelength division multiplexing (WDM) networks. In practice, wavelength converters (WCs) are either absent or only sparsely deployed in WDM networks due to economic and technical limitations. Thus, wavelength assignment is expected to be an important component of OBS networks. In this paper, an offline wavelength assignment scheme in OBS networks without wavelength conversion capability is proposed. The key idea of the scheme is to decide the wavelength searching order of each traffic connection at edge nodes according to the wavelength priorities determined by the calculated burst loss probabilities on different wavelengths. Simulation results indicate that the proposed scheme can reduce the network-wide burst loss probability significantly compared with other schemes. It is also illustrated that the performance of the proposed scheme can be further enhanced by a larger number of wavelengths per link and a reasonable delay bound at edge nodes.     

一种稀疏分光配置约束下的WDM网络多播RWA算法

在波长路由WDM网络中,波长路由和波长分配是RWA算法提高光网络阻塞性能的两个重要阶段和关键技术。文章针对现有的稀疏分光配置约束下的光网络多播RWA算法复杂度高、代价高的问题,提出了一种新的稀疏分光器配置的RWA多播算法。该算法摒弃传统RWA算法在波长路由阶段就考虑稀疏分光约束能力的惯性思维,论文首次提出在波长分配阶段,才通过多播长转换器实现满足稀疏分光约束条件的分光能力传递。仿真结果表明,所提算法在平均代价和所需波长数目方面都获得了较优的性能。     

Virtual-node-based multicast routing and wavelength assignment in sparse-splitting optical networks

This paper investigates several problems associated with optical multicast routing and wavelength assignment in sparse-splitting optical networks for interactive real-time media distribution. Unfortunately, the constrained multicast routing with optimized wavelength assignment leads to NP-complete condition. Thus, in this paper, a virtual-node-based multicast routing algorithm is first proposed to satisfy the requirements of interactive real-time multicasting as well as the constraints from underlying optical networks. For the constructed multicast tree, we then associate an effective wavelength assignment algorithm. The experimental results show that the proposed algorithm combination performs well in terms of (1) the wavelength channel cost, (2) the maximum variation of inter-destination node delays, (3) the signal quality, and (4) the number of wavelength conversions.     

有限波长转换能力的OBS网波长分配算法研究

结合国内外最新的研究动态,针对有限波长转换能力的光突发交换网中亟待解决的突发包资源竞争问题,探讨了各种传统的波长分配算法,并通过对其特点的分析和综合比较,提出了一种新的适合有限波长转换能力光突发交换网特点的动态波长分配算法,此算法可以实现更低的全网突发包阻塞率.     

Efficient routing and wavelength assignment for multicast in WDMnetworks

The next generation multimedia applications such as video conferencing and HDTV have raised tremendous challenges on the network design, both in bandwidth and service. As wavelength-division-multiplexing (WDM) networks have emerged as a promising candidate for future networks with large bandwidth, supporting efficient multicast in WDM networks becomes eminent. Different from the IP layer, the cost of multicast at the WDM layer involves not only bandwidth (wavelength) cost, but also wavelength conversion cost and light splitting cost. It is well known that the optimal multicast problem in WDM networks is NP-hard. In this paper, we develop an efficient approximation algorithm consisting of two separate but integrated steps: multicast routing and wavelength assignment. We prove that the problem of optimal wavelength assignment on a multicast tree is not NP-hard; in fact, an optimal wavelength assignment algorithm with complexity of O(NW) is presented. Simulation results have revealed that the optimal wavelength assignment beats greedy algorithms by a large margin in networks using many wavelengths on each link such as dense wavelength-division-multiplexing (DWDM) networks. Our proposed heuristic multicast routing algorithm takes into account both the cost of using wavelength on links and the cost of wavelength conversion. The resulting multicast tree is derived from the optimal lightpaths used for unicast