共查询到19条相似文献,搜索用时 171 毫秒
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一种稀疏分光配置约束下的WDM网络多播RWA算法 总被引:1,自引:0,他引:1
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。 相似文献
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Kouji Hirata Yutaka Fukuchi Masahiro Muraguchi 《Photonic Network Communications》2013,26(2-3):120-130
This paper proposes a dynamic lightpath establishment scheme considering four-wave mixing (FWM) in multifiber wavelength-division multiplexed (WDM) all-optical networks. The FWM is one of the most important physical impairments to be resolved in WDM networks because the FWM induces nonlinear inter-channel crosstalk and decays the performance of WDM networks. In WDM networks, data are transmitted via lightpaths. When the effect of FWM crosstalk is large, it is highly possible that data transmission fails even if lightpaths are correctly established. The proposed scheme aims to avoid not only the blocking of lightpath establishment but also the accumulation of FWM crosstalk by means of ingenious selection of routes, wavelengths, and fibers for lightpath establishment. In the proposed scheme, a route and a wavelength are selected for each lightpath based on wavelength availability and wavelength placement of established lightpaths. Furthermore, fibers on the route are selected based on estimated FWM power. In this paper, we show the effectiveness of the proposed scheme through simulation experiments. 相似文献
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In this letter, we propose a computational model for calculating blocking probabilities of multifiber wavelength division multiplexing (WDM) optical networks. We first derive the blocking probability of a fiber based on a Markov chain, from which the blocking probability of a link is derived by means of conditional probabilities. The blocking probability of a lightpath can be computed by a recursive formula. Finally, the network-wide blocking probability can be expressed as the ratio of the total blocked load versus the total offered load. Simulation results for different fiber-wavelength configurations conform closely to the numerical results based on our proposed model, thus demonstrating the feasibility of our proposed model for estimating the blocking performance of multifiber WDM optical networks. 相似文献
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Tong Ye Qingji Zeng Yikai Su Lufeng Leng Wei Wei Zhizhong Zhang Wei Guo Yaohui Jin 《Selected Areas in Communications, IEEE Journal on》2004,22(9):1681-1691
This paper focuses on dynamic integrated routing in multifiber Internet protocol/wavelength-division multiplexing (IP/WDM) networks, which can be implemented through either one-step routing (OSR) or two-step routing (TSR) approach. Based on an extended layered-graph, two resource assignment strategies, termed channel-level balance (CLB) and link-level balance (LLB), are proposed to balance the traffic in the network at different levels. To further improve the performance, a parameter K is introduced to make a dynamic tradeoff between the logical-layer links and the optical-layer links. Simulation studies are carried out for various topologies. The results show that LLB is better than CLB in most cases, and LLB combined with OSR has the optimal performance. Also, we find that the routing approach and the resource assignment strategy individually play different roles with different values of r/sub l/ that is introduced to indicate the resource richness of the network. As a multifiber network is functionally equivalent to a single-fiber network with limited wavelength conversion, we investigate the effects of wavelength conversion by studying the multifiber IP/WDM networks. The analysis shows that, when the granularity of each connection request is much smaller than the wavelength granularity, wavelength conversion may increase the request blocking probability in the network. 相似文献
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We consider the effect of multiple fibers on wavelength division multiplexing networks without wavelength conversion. We study networks with dynamic wavelength routing and develop accurate analytical models to compare various possible options using single- and multiple-fiber networks. We use results of an analytical model and simulation-based studies to evaluate the blocking performance and cost of multifiber networks. The number of fibers required providing high performance in multifiber networks and their costs are compared. A case is made for using multiple fibers in each link with fewer wavelengths instead of using a single fiber with many wavelengths. In particular, we show that a network with four fibers per link and with four wavelengths on each fiber without any wavelength conversion on any node yields similar same performance as the networks with one fiber per link and 16 wavelengths per fiber on each link and with full wavelength conversion capability on all nodes. In addition, the multifiber network may also offer the cost advantage depending on the relative cost of components. We develop a parametric cost model to show that multiple fibers in each link are an attractive option. Finally, such multifiber networks also has fault tolerance, with respect to a single fiber failure, already built into the system. 相似文献
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This paper studies-the off-line wavelength assignment problem in star and ring networks that deploy multiple fibers between nodes and use wavelength division multiplexing (WDM) for transmission. The results in this paper show that the ability to switch between fibers increases wavelength utilization. In particular, sharper per-fiber bounds on the number of required wavelengths are derived for the multifiber version of the assignment problem in star and ring networks. Additionally, the complexity of the problem is studied and several constrained versions of the problem are also considered for star and ring networks. A summary of contributions is provided 相似文献
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We consider the problem of network design in transparent, or clear channel, optical networks associated with wavelength-division multiplexing (WDM). We focus on the class of traffic engineering models known as routing, wavelength, and capacity assignment problems. Here, in contrast to traditional networks, traffic flow paths must also be assigned an end-to-end wavelength. This additional requirement means that there can be an increased cost associated with optimal capacity allocations for such WDM-flows. In general, this can be arbitrarily worse than traditional network designs. We argue that in order to evaluate the benefit of different switch technologies, a good benchmark is to measure the increase in costs purely in terms of link capacity, we call this the cost of transparency. Experimental research shows that this cost is small in multifiber networks with modest switching functionality at the nodes. We present theoretical justification for why this occurs, and prove that in multiwavelength multifiber transparent networks the cost of transparency all but disappears if there is moderate traffic load. Our arguments are based on efficient heuristics that may also be useful for more complex network optimizations. This suggests that the cost savings from using wavelength converters is significant only in young networks with relatively few fibers lit. Such savings may, thus, be small relative to the initial capital expense involved in installing wavelength conversion. 相似文献
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Analytical blocking probability analysis is important for network design. In this paper, we present an analytical model for the blocking probability analysis on adaptive routing over the WDM networks with finite wavelength conversion capability. Modeling the finite nature of wavelength conversion has been a difficult task. We make use of the idea of segmented route to handle the finite wavelength conversion property. In this approach, a route is divided into a number of segments separated by wavelength converting nodes. We then combine the single-link model and the overflow model to derive the network-wide blocking probability. There are two distinct features in our technique. First, a concept of segmented route is used. Second, link state is considered when calculating the traffic flow. The latter ensures that the analytical results match closely to practical network status. Extensive simulations show that the analytical technique is effective in modeling the blocking probability performance for sparse networks. 相似文献
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This paper considers wavelength routed WDM networks where multiple fibers are used for each communication link. For such networks, the effect of wavelength translation can be achieved without explicit use of wavelength translators. We call this as virtual wavelength translation and study the routing issues considering dynamic lightpath allocation. Using multiple (or a bundle of) fibers for each link also allows us to have bundles of varying sizes to accommodate anticipated differences in traffic through different communication links of the network. The paper considers the blocking probabilities of all-optical networks when centralized and distributed lightpath allocation schemes are used. 相似文献
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Theelen B. D. Voeten J. P. M. van der Putten P. H. A. Stevens M. P. J. Dorren H. J. S. 《Photonic Network Communications》2002,4(1):47-62
To satisfy the severe requirements involved in future communication networks, commercial and research interest in the applicability of wavelength division multiplexing (WDM) is growing. However, since WDM is merely concerned with transmitting bits over optical fibers, full advantage can only be taken when WDM is efficiently supported by higher-layer protocols. Functionality of higher-layer protocols that could be used in conjunction with WDM originates from synchronous digital hierarchy (SDH) or synchronous optical network (SONET), asynchronous transfer mode (ATM), and the internet protocol (IP). To provide flexible use of services with different levels of quality, various higher-layer protocols may directly support WDM simultaneously by reserving wavelength channels for a specific supporting protocol. Focussing on aspects of network management, this paper investigates how the mentioned higher-layer protocols may concurrently support WDM. 相似文献