共查询到17条相似文献,搜索用时 187 毫秒
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共享有限范围多波长和全单波长转换器的光组播冲突解决方案 总被引:4,自引:4,他引:0
研究了一种有限范围多波长转换器(LMWC)反馈共享连接和全单波长转换器(FRWC)输出共享连接相结合的解决全光组播波长资源竞争的解决方案,并提出有限范围多波长转换器优先的波长变换调度算法,以最大双向匹配最小边长权重方法选择多波长转换器解决冲突光组播波长变换。仿真结果表明:所提的结构与输出共享全多波长转换器(FMWC)节点结构或输出共享FRWC节点结构相比,都能够明显降低光组播节点的分组丢包率(PLP),减少系统需求LM-WC多波长转换器的数目,提高多波长转换器的利用率;LMWC具有不同波长转换范围对光分组冲突解决性能也有影响。 相似文献
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基于共享有限波长和参量波长转换器的冲突解决方案 总被引:1,自引:0,他引:1
研究了一种共享有限波长转换器(LRWC)和参量波长转换器(PWC)相结合的解决全光分组波长资源竞争的方案,并提出了PWC优先算法作为光分组交换中的波长竞争解决方案。仿真结果表明:本文结构与共享LRWC节点结构相比,减少了波长转换器的数目,并且能够明显降低光分组交换节点的分组丢包率(PLP),提高波长转换器的利用率。研究还发现,不同波长转换器配置方案对系统性能有影响。 相似文献
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光分组在核心节点处的冲突解决问题是实现全光 组播分组交换的关键。本文提出了一种新型的解决光组播冲突的节 点结构,用于冲突解决的部分包括输出共享的网络编码模块和光纤延迟线(FDL)环 形反馈共享缓存(FDL-LSFB)模块。网络编码 模块将异或网络编码作为冲突解决方式,利用全光异或门将冲突组播进行网络编码并且改变 编码后分组波长,从而避免波长 冲突。而FDL-LSFB模块由子交换矩阵和FDL缓存组连接成环状,且冲突组 播可从任意子交换矩阵进出缓存模块, 使用少数的FDL可以提供大容量的光缓存、提高FDL利用率。针对FDL-LSFB模块冲突组播调 度问题,为减小缓存时延,设计了最小缓存长度级联控制算法(MLCBST),进而提出冲突光 组播的总调度策略。仿真结果表明,本文提出的组播节点结构和调度策略在降低丢包率(PLP)和减小缓存时延方面具有明显的效果。 相似文献
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将一种新的光缓存技术--慢光可变延时缓存器,与可调波长转换器结合,构成光分组交换模型.简要分析了慢光缓存器的时延特性,并对其解决信息网络交换拥塞进行了应用设计与仿真,分析结果表明,慢光缓存器与光纤延迟线缓存相比较,不仅能更有效地降低丢包率,而且还可以简化光分组交换的结构,其体积更小,使用更灵活. 相似文献
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提出了一种基于业务负载选择的光分组交换(OPS)网络的光缓存结构,根据业务负载大小灵活选择缓存方式。输出缓存光纤延迟线(FDL)采用分段式共享机制配置,输出/反馈共享缓存模块采用简并式配置,以提高有限数目FDL的利用率。分析和仿真表明,这种可选择的缓存结构可以有效降低丢包率和OPS节点需求的FDL数目。 相似文献
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Develder Chris Houdt Benny Van Blondia Chris Pickavet Mario Demeester Piet 《Photonic Network Communications》2004,8(2):149-161
The major goal of optical packet switching (OPS) is to match switching technology to the huge capacities provided by (D)WDM. A crucial issue in packet switched networks is the avoidance of packet losses stemming from contention. In OPS, contention can be solved using a combination of exploitation of the wavelength domain (through wavelength conversion) and buffering. To provide optical buffering, fiber delay lines (FDLs) are used. In this paper, we focus on an optical packet switch with recirculating FDL buffers and wavelength converters. We introduce the Markovian arrival process with marked transitions (MMAP), which has very desirable properties as a traffic model for OPS performance assessment. Using this model, we determine lower and upper bounds for the packet loss rate (PLR) achieved by the aforementioned switch. The calculation of the PLR bounds through matrix analytical methods is repeated for a wide range of traffic conditions, including highly non-uniform traffic, both in space (i.e., packet destinations) and time (bursty traffic). The quality of these bounds is verified through comparison with simulation results. 相似文献
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In this paper, we study routing and wavelength assignment of connection requests in survivable WDM optical mesh networks employing shared path protection with partial wavelength conversion while 100% restorability is guaranteed against any single failures. We formulate the problem as a linear integer program under a static traffic model. The objective is to minimize the total cost of wavelength-links and wavelength converters used by working paths and protection paths of all connections. A weight factor is used which is defined as the cost ratio of a wavelength converter and a wavelength-link. Depending on the relative cost of bandwidth and wavelength conversion, the optimization objective allows a proper tradeoff between the two. The proposed algorithm, the shortest-widest-path-first (SWPF) algorithm, uses a modified Dijkstra's algorithm to find a working path and a protection path for each connection request in the wavelength graph transformed from the original network topology. When there are multiple candidate paths that have the same minimum total cost, the path along which the maximum number of converters used at each node is minimized is chosen by the SWPF algorithm. We have evaluated the effectiveness of the proposed algorithm via extensive simulation. The results indicate that the performance of the proposed algorithm is very close to that of the optimal solutions obtained by solving the ILP formulation and outperforms existing heuristic algorithms in terms of total number of converters used and the maximum number of converters required at each node in the network. The proposed algorithm also achieves slightly better performance in terms of total cost of wavelength-links and converters used by all connections. We also investigated shared path protection employing converter sharing. The results show that the technique can reduce not only the total number of converters used in the network but also the maximum number of converters required at each node, especially when a large number of converters are needed in the network. In this study, although the ILP formulation is based on static traffic, the proposed algorithm is also applicable to routing dynamic connection requests. 相似文献
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In this paper, a novel optical packet switch is proposed, which uses a set of shared fiber delay lines (FDLs) and a set of
shared tunable wavelength converters (TWCs) to resolve optical packet contentions. In addition, two control algorithms, i.e.,
Fiber-First (FF) and Wavelength-First (WF), are proposed to schedule optical packets. Performance of the novel switch is evaluated
by means of simulation experiments. Simulation results show that based on either of these two control algorithms, the switch
can achieve super performance without employing a lot of FDLs and TWCs. Moreover, the performance of FF and WF is compared.
Detail analyses are also given in this paper. 相似文献
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A novel two-layer wavelength conversion (TLWC) scheme, for reducing the implementation cost of an optical switching (OS) node, is presented in this paper. The study stems from practical observation that wavelength converters are expensive. The paper thus presents a new OS node architecture that uses significantly less wavelength converters without compromising on drop performance. In this TLWC system, partial wavelength converters (PWCs), which can only convert wavelengths within a limited range, form the first layer; thereafter, complete wavelength converters (CWCs), which can convert wavelengths within all input ranges, form the second layer. When new optical data needs a wavelength converter, PWC resources are first provided; if PWC resources are not available, CWC resources are used. For the case of the CWC layer, a sharing-mode scheme called the share per fiber (SPF) mode for improving the utilization of the limited number of wavelength converters is proposed. Subsequently, a two-dimensional Markov-chain model of TLWC-SPF is presented to evaluate its performance. Numerical-simulation results are presented to verify the accuracy of the analytical model. The analysis shows that the cost of the OS fabric of TLWC-SPF is similar to an OS node employing a limited number of CWCs (i.e., CWC-SPF). However, in terms of wavelength-converter savings, the TLWC-SPF architecture provides 50% (in heavy load) savings compared to full wavelength conversion (FWC) optical nodes, while 40% savings is achieved compared against CWC-SPF nodes. 相似文献
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Masetti F. Benoit J. Brillouet F. Gabriagues J.M. Jourdan A. Renaud M. Bottle D. Eilenberger G. Wunstel K. Schilling M. Chiaroni D. Gavignet P. Jacob J.B. Bendelli G. Cinato P. Gambini P. Puleo M. Martinson T. Vogel P. Durhuus T. Joergensen C. Stubkjaer K. Baets R. Van Daele P. Bouley J.C. Lefevre R. Bachmann M. Hunziker W. Melchior H. McGuire A. Ratovelomanana F. Vodjdani N. 《Selected Areas in Communications, IEEE Journal on》1996,14(5):979-998
This paper describes the work carried out in the RACE Project R2039 ATMOS (asynchronous transfer mode optical switching). The project is briefly illustrated, together with its main goal: to develop and assess concepts and technology suitable for optical fast packet switching. The project's technical approach consisted in the exploitation of the space and wavelength domains for fast routing and buffering: The major achievements are then reported. Four different switch architecture concepts have been proposed, investigated and developed, all based on a high speed optical routing matrix electrically controlled at lower speed. The basic optical key components and subsystems (wavelength converters, space switches and optical buffers) are described in detail, with the outstanding results obtained and the corresponding projected performance. In particular, system demonstration of wavelength conversion at 10 and 20 Gb/s has been realized, to show the usefulness of the ATMOS technology both to implement optimized high performance optical packet-switching fabrics as well as transparent optical circuit-routing nodes. Four rack-mounted, reduced size demonstrators of basic switching matrices have been designed and implemented scalable to real system sizes. The obtained good results in terms of bit error rate and hardware integration are reported, showing that ATM switches are feasible with state of-the-art optical technology 相似文献
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Resources sharing in optical packet switches with limited-range wavelength converters 总被引:4,自引:0,他引:4
This paper compares selected optical packet switching architectures that use the wavelength conversion technique to solve the packet contention problem. The architectures are equipped with shared and limited-range wavelength converters (LRWCs). This paper focuses on two architectures: the shared per node (SPN) and the shared per output fiber (SPOF) architectures, in which the wavelength converters are SPN and output fiber, respectively. Packet loss probability is expressed as a function of the number of wavelength converters used, by means of analytical models validated by simulations. The analytical results show how the use of a reduced number of LRWCs with small range allows the switch to obtain the same performances of an architecture equipped with all of the wavelength converters and using a full wavelength conversion. 相似文献