共查询到20条相似文献,搜索用时 15 毫秒
1.
全分散控制数字程控交换系统广泛采用分布式数字交换网络,其阻塞概率和设备配置是设计中必须考虑的重要问题。本文对近期报导的基于3 种阻塞成分的算法作了明显改进,提出了不受通信模块数量限制的通用计算方法,并使得计算简化和规则化 相似文献
2.
本文介绍了光突发交换的网络原理、网络结构和模块功能,结合国内外的研究成果,总结和讨论了光突发交换的资源预约机制,分析了它们的网络性能。 相似文献
3.
4.
该系统基于射频芯片全分布式无线通信协议,具有载波检测和冲突避免功能,解决多对一通信问题;采用主从一致性更新策略,解决分布式系统数据一致性问题。基于这些技术,成功研制了一套仪器设备控制管理系统,实现了仪器设备预约与使用过程控制相结合,提高了实验室仪器设备管理的自动化水平。 相似文献
5.
A Multi-Hop Resource Reservation Scheme for Seamless Real-Time QoS Guarantee in WiMedia Distributed MAC Protocol 总被引:1,自引:1,他引:0
In this paper, a multi-hop range conflict-free resource reservation scheme for UWB (Ultra Wide Band) WPAN (Wireless Personal
Area Network) with D-MAC (Distributed Medium Access Control) is proposed. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC
UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized
and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized
IEEE 802.15.3 MAC. However, since each device’s mobility perspective in multi-hop environment has not been taken into account
in the current WiMedia D-MAC, it may cause a “mobile” hidden node problem. In addition, once a DRP conflict occurs due to
the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs,
while the other DRP reservations must be terminated and DRP negotiations for them have to be re-started although only a few
MASs are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem
to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mechanism to prevent and resolve
multi-hop range DRP conflicts due to each device’s mobility in D-MAC environment and demonstrate its guaranteed Seamless QoS
and prioritized real-time QoS performances via numerical analyses. 相似文献
6.
Delay-on-Demand: A Signaling Protocol to Reduce Blocking Probability in Optical Burst-Switching Networks 总被引:2,自引:0,他引:2
Optical burst switching (OBS) is emerging as one promising switching paradigm for the next generation optical networks. To support multiple services in burst-switching networks, the OBS paradigm should support some quality-of-service (QoS) provisioning. A major design issue in such networks is to reduce the blocking probability of the bursts arising due to resource contention at the intermediate core router. In this paper, we propose a signaling protocol which we call ‘Delay-on-Demand’ (OBS-DoD), to reduce blocking probability and support QoS in optical burst-switching networks. The proposed scheme guarantees that at least one of the bursts succeeds depending on its priority, propagation delay from the ingress router, and the burst-size when contention occurs at the core router. For this, we use a control packet to delay, in case of a contention, the transmission of bursts at the ingress router. We compare the performance of our proposal, by simulation, with an earlier proposed scheme, and show that the proposed OBS-DoD outperforms the earlier scheme in reducing the blocking probability. For simulation, we generated bursty traffic using an M/Pareto distribution. 相似文献
7.
In this letter, we design a collision resolution protocol for optical burst switching ring networks to avoid burst collision. We define the offset time condition for no burst transmission collision and manage the free time list of nodes for no burst reception collision. In order to improve the throughput, we use a fiber delay line, void‐filling, and void‐compression. This protocol does not require any additional procedures for bandwidth reservation such as centralized assignment of bandwidth, lightpath setup of WDM ring networks, or token capturing for the burst transmission. The simulation results show that the proposed protocol can achieve high throughput while saving 70% of wavelengths when compared to round robin with random selection, round robin with persistent, and round robin with non‐persistent with only destination delay. 相似文献
8.
Fair bandwidth allocation (FBA) has been studied in optical burst switching (OBS) networks, with the main idea being to map the max-min fairness in traditional IP networks to the fair-loss probability in OBS networks. This approach has proven to be fair in terms of the bandwidth allocation for differential connections, but the use of the ErlangB formula to calculate the theoretical loss probability has made this approach applicable only to Poisson flows. Furthermore, it is necessary to have a reasonable fairness measure to evaluate FBA models. This article proposes an approach involving throughput-based-FBA, called TFBA, and recommends a new fairness measure that is based on the ratio of the actual throughput to the allocated bandwidth. An analytical model for the performance of the output link with TFBA is also proposed. 相似文献
9.
10.
提出一种解决光突发交换(OBS)网络节点中突发数据包冲突的方案.发生冲突时,在OBS层重传被丢弃突发数据包,然后给出评估这种重传机制丢包率的方法,并与偏射路由策略的性能进行比较,结果表明突发重传机制显著改善了丢包率.可以很好地实现服务质量(QoS)机制. 相似文献
11.
12.
Distributed Control Protocols for Wavelength Reservation and their Performance Evaluation 总被引:6,自引:0,他引:6
This paper describes distributed (or decentralized) protocols for establishing wavelength paths in point-to-point WDM networks. Distributed control improves reliability as well as scalability and reduces implementation cost of a network, but also presents major challenges in managing/allocating wavelengths efficiently. Two types of distributed wavelength reservation protocols are proposed and evaluated, namely forward and backward. The benefit of wavelength conversion is assessed first based on the evaluation of the forward reservation protocols, and it is found that wavelength conversion can result in a performance advantage in a distributed environment. For networks without wavelength conversion, a class of backward reservation protocols is studied and shown to generally perform better than their forward counterparts. 相似文献
13.
Burst Assembly Schemes and Performance Evaluation in Optical Burst Switching Networks 总被引:2,自引:0,他引:2
1 Introduction TheopticalInternethasbeenemergedasanefficientsolutionforsupportingever increasingInternettrafficbytakingadvantageofpotentiallyhugebandwidthofWavelength DivisionMultiplex (WDM )opticalnet works.Tomeettheincreasingbandwidthdemandsandreducecosts ,severalopticalnetwork paradigmshavebeenunderintensiveresearch .Ofalltheseparadigms,OpticalCircuitSwitching (OCS[1~ 3] )isrelativelyeasytoimplementbutlacksflexibilitytocopewiththefluc tuatingtrafficandthechanginglinkstate ,andrequi… 相似文献
14.
Distributed wavelength reservation protocols are employed to dynamically set up and tear down lightpaths in WDM networks. In this paper, discrete event-driven simulations are carried out to investigate the performance of different protocols under both single and multi-fiber circumstances. Simulation results indicate that the behavior of these protocols varies noticeably between single and multi-fiber networks. Discussions on these results are also presented. It is found that the preferred scheme in the literature, which adopts backward reservation with random wavelength selection, does well in single-fiber scenarios. But this scheme fails to be excellent in multi-fiber scenarios since it cannot take full advantage of multiple fibers. Then, we extend the reservation protocols for multi-fiber networks and propose a novel wavelength selection policy called Maximum-Availability policy. Results show that our scheme will give an outstanding performance in both single and multi-fiber networks. 相似文献
15.
提出一种不等概率输出模型,该模型考虑到不同输出端口具有不同的服务率,赋予不同端口以不同的选择概率.最后,通过计算突发数据分组阻塞率详细分析了输出端口的服务率和选择概率之间的关系. 相似文献
16.
结合资源预留的分布式QoS组播路由算法 总被引:2,自引:0,他引:2
针对网络资源信息的动态变化对QoS组播路由算法的巨大影响,该文提出了一种与资源预留结合的分布式组播路由算法DQMTR。DQMTR通过在路径探索过程中进行资源预留克服网络信息变化对QoS路由算法的影响。DQMTR还通过记录预约资源的数量解决资源的过预约问题,并利用DiffServ体系下QoS路由算法的特点使算法能够适用于DiffServ网络。仿真实验表明,DQMTR提高了组成员加入的成功率,优化了平均路径代价值。 相似文献
17.
18.
提出了一种新的光突发装配技术,目的在于增强光突发交换(OBS)网络的服务质量(QoS)能力。该技术由自适应门限突发装配算法和基于优先级的随机化的偏移时间设置方案构成。该装配算法特别适合于多类别分组混合装配,能让所有类别的分组公平有效地使用装配能力,能较好地与IP层的QoS机制相匹配。偏移设置方案将突发控制分组(BCP)与突发数据(BP)间的偏移时间分成QoS偏移和随机偏移,前者由改进的JET协议按照有选择性的突发段丢弃机制(BSSD)确定,后者则由令牌桶机制确定。BSSD仅丢弃包含有低类别分组的突发段,而非整个突发。计算机仿真结果表明,本文提出的突发装配技术在性能上具有优越性。 相似文献
19.