共查询到19条相似文献,搜索用时 109 毫秒
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光突发交换(OBS)网络中数据信道的调度算法是提高OBS网络性能的关键技术之一.文章给出了LAUC、LAUC-VF、BR和LAUC-VF-BS等几种数据信道调度算法的基本原理,通过仿真对这些调度算法进行了性能比较,结果表明LAUC-VF-BS算法能够更有效地降低突发丢失率,提高信道利用率,从而改善网络性能. 相似文献
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根据光突发交换(OBS)网络核心节点的结构和功能 特点,分析了OBS网络核心节点的数据信道 调度算法,提出了一种新的基于标记可抢占调度算法(LPSA),并讨论和分析了算法的实 现过程。本文算法根据到达核心节点的控制包所属业务等级的突发数据(OB)包占用的网络带 宽决定 数据信道调度的方法,实现了合理的使用数据信道和各业务类别间的业务区分,最终达到改 善OBS网络性能的目的。 相似文献
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数据信道调度是OBS核心路由器的关键技术之一,文章对数据信道的几种调度算法进行了分析.在此基础上,介绍了一种改进的波长调度算法.网络仿真结果表明,该算法可以有效改善网络性能. 相似文献
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光突发包交换关键技术概述 总被引:1,自引:0,他引:1
光突发包交换(OBS)技术是近年来出现的一种新型光交换技术,它结合了波长路由和光分组交换的优点,是一种未来一段时间内交换网络比较理想的过渡方案,为此介绍了OBS的基本原理,讨论了OBS中偏置时间的设置和交换信道的调度等关键技术,并就OBS的特点及仍需解决的问题作了总结。 相似文献
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OBS网络中的最小间隙组调度算法 总被引:1,自引:1,他引:0
根据OBS网络的结构和特点,分析了OBS网络核心节点的数据信道调度算法,提出了一种新的数据信道调度算法--最小间隙组调度(SGGS)算法,并详细讨论了该算法的具体实现.该算法将到达核心节点的控制包分组,然后将这一组控制包按数据包到达先后的次序调度数据信道,从而达到合理调度和使用数据信道,最终实现改善整个OBS网络性能的目的. 相似文献
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OBS网络中的多BHP延迟调度算法 总被引:2,自引:0,他引:2
光突发交换 (Optical Burst Switching,OBS) 是下一代光网络中的有效核心交换技术之一。在OBS网络中,核心节点的调度方案是影响网络交换性能的重要因素。如何有效地对突发分组 (Burst) 进行合理调度,以减少丢包率正是关键问题所在。该文提出了一种多控制分组 (Burst Header Packet,BHP) 延迟调度算法,对于一个收集周期内到达的多个BHP所对应的突发数据,按照一定的方式对它们进行集中调度,实现对已预约资源的更改,使调度结果得到了优化。该算法根据不同的网络应用,可细化为4种具体的算法实现,以适用于不同的应用场景。仿真结果表明,该文提出的调度算法和已有算法相比,能够优化对突发分组的调度,提高对信道资源的有效使用,从而降低交换网络的丢包率。 相似文献
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Optical burst switching (OBS) presents itself as a promising technology for bridging the gap between optical wavelength switching
and optical packet switching. Increasingly, researchers attempt to incorporate more realistic constraints into the design
of OBS networks. Optical signal transmission quality is subject to various types of physical impairment introduced by optical
fibers, switching equipment, or other network components. The signal degradation due to physical impairments may be significant
enough such that the bit-error rate of received signals is unacceptably high at the destination, rendering the signal not
usable. In this paper, based on earlier work, we study the burst scheduling problem in OBS networks, taking into account physical
impairment effects. We propose three effective burst scheduling algorithms: (1) a JET based Physical Impairment Constrained
Algorithm (JETPIC), (2) an Integrated Physical Impairment Constrained Algorithm (IPIC), and (3) an Enhanced Integrated Physical
Impairment Constrained Algorithm (EIPIC). At an OBS node, the proposed algorithms schedule bursts for transmission by searching
for available resources as well as verifying signal quality. Our simulation results show that the proposed algorithms are
effective in terms of reducing the burst blocking probability. In general, algorithm JETPIC outperforms algorithms IPIC and
EIPIC in burst blocking probability and average end-to-end delay performance.
相似文献
Bin WangEmail: |
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Xiang Yu Jikai Li Xiaojun Cao Yang Chen Chunming Qiao 《Lightwave Technology, Journal of》2004,22(12):2722-2738
Optical burst switching (OBS) is a promising switching technology to exploit the potential benefits of optical communication and, at the same time, support statistical multiplexing of data traffic at a fine granularity. To quantify its benefits, the paper describes several typical burst assembly algorithms and studies their impact on the assembled burst traffic characteristics as well as the performance of TCP traffic. Also described is a proactive burst scheduling algorithm, called burst overlap reduction algorithm (BORA), which schedules locally assembled bursts in such a way as to reduce burst contention at downstream nodes in OBS networks. Furthermore, to provide analytical insights into performance evaluation of OBS networks, a burst loss model at an OBS node and its extension to different reservation protocols are presented. 相似文献
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Optical Burst Switching (OBS) is an emerging technology that allows variable size data bursts to be transported directly over
DWDM links without encountering O/E/O conversion. In OBS, before the transmission of a data burst, a burst header is transmitted
through an electronic control path, setting up and tearing down optical paths on-the-fly. Data bursts can remain in the optical
domain and pass through the OBS network transparently. Unfortunately, system performance will be greatly degraded, if burst
scheduling requests cannot be processed in time. This article quantitatively studied the negative impact of control path overloading
on the performance of OBS networks. Results have shown that control path overloading greatly affects the performance of the
OBS routers, especially for systems with large WDM channel counts. In order to remove this performance bottleneck, we have
designed and implemented an ultra fast pipelined burst scheduler that is able to process a burst request every two clock cycles,
regardless of the number of WDM channels per link. The design has been implemented in Verilog HDL and synthesized to FPGAs.
Circuit level simulation results confirm the correctness of the design. The circuit has achieved 100 MHz in Altera Cyclone
II devices, allowing the scheduler to process a burst request every 20 ns. To the authors’ best knowledge, this is the fastest
implementation of burst scheduling algorithms. 相似文献
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Saravut Charcranoon Tarek S. El-Bawab Jong-Dug Shin Hakki C. Cankaya 《Photonic Network Communications》2006,11(1):99-110
We propose a new burst scheduling mechanism for Optical Burst-Switched (OBS) networks. The new approach is made possible by
gathering data bursts into groups and performing the scheduling decision for each group collectively. In OBS group-scheduling,
bursts will not be considered for scheduling until a pre-defined time period elapses, during which the group of burst header
packets would be gathered. By transforming a set of data bursts into a set of corresponding time intervals, the problem of
scheduling these bursts is transformed into a combinatorial optimization problem. Graph algorithms are applied to obtain the
maximum number of non-overlapping bursts. The proposed OBS group-scheduling scheme is shown to improve the performance of
OBS networks over existing scheduling schemes in terms of burst loss probability and channel utilization. With an extension
through a sequential optimization, using a Branch-and-Bound technique, the proposed scheme can support multiple classes of
service. It is shown that the new scheduling approach has several desired characteristics including fairness and service differentiability
among classes in terms of burst loss probability and channel utilization. 相似文献
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Efficient burst scheduling algorithms in optical burst-switched networks using geometric techniques 总被引:4,自引:0,他引:4
Jinhui Xu Chunming Qiao Li J. Guang Xu 《Selected Areas in Communications, IEEE Journal on》2004,22(9):1796-1811
Optical burst switching (OBS) is a promising paradigm for the next-generation Internet. In OBS, a key problem is to schedule bursts on wavelength channels, whose bandwidth may become fragmented with the so-called void (or idle) intervals, using both fast and bandwidth efficient algorithms so as to reduce burst loss. To date, two well-known scheduling algorithms, called Horizon and LAUC-VF, have been proposed in the literature, which trade off bandwidth efficiency for fast running time and vice versa, respectively. In this paper, we propose a set of novel burst scheduling algorithms for OBS networks with and without fiber delay lines (FDLs) utilizing the techniques from computational geometry. In networks without FDLs, our proposed minimum-starting-void (Min-SV) algorithm can schedule a burst in O(logm) time, where m is the total number of void intervals, as long as there is a suitable void interval. Simulation results suggest that our algorithm achieves a loss rate which is at least as low as LAUC-VF, but can run much faster. In fact, its speed can be almost the same as Horizon (which has a much higher loss rate). In networks with FDLs, our proposed batching FDL algorithm considers a batch of FDLs to find a suitable FDL to delay a burst which would otherwise be discarded due to contention, instead of considering the FDLs one by one. The average running time of this algorithm is therefore significantly reduced from that of the existing burst scheduling algorithms. Our algorithms can also be used as algorithmic tools to speed up the scheduling time of many other void-filling scheduling algorithms. 相似文献