A Markov-Based Reservation Algorithm for Wavelength Assignment in All-Optical Networks

Most routing and wavelength assignment algorithms for all-optical networks do not consider the potential problem of reservation connection, which occurs when two or more reservation requests compete for the same wavelength. Confliction can happen even if the network is only lightly loaded. In this paper, we propose a new reservation protocol Markov-based backward reservation (MBR) based on Markov modeling of the network traffic on optical links for resolving wavelength reservation confliction. Our simulations show that this new protocol can improve network performance as measured by decreased blocking probability. The MBR algorithm works best in small-hop-count networks with a comparatively small number of wavelengths per fiber compared to other frequently considered algorithms.     

单跳波分复用网络中的优化数据传送策略

本文研究无源生形波分复用网络中数据传送的变化。在传统策略的基础上，本文提出了两各优化方案；最早发送时间数据传送策略和最小发送间隙数据传送策略，计算机模拟结果表明现任中优化部有力地改进了网络性能，既能显著地提高网络吞吐量，又极大地减小分组时延。     

一种新的应用于光突发交换网络保证流量均衡的波长调度算法

在现有波长调度方法(LAUC_VF)的基础上,结合跳数优先级技术和动态资源分配技术,提出了一种新的可以提供流量均衡的波长调度算法(HP_JET)。通过仿真,证明这种波长调度算法在改善全网阻塞率以及均衡流量方面比原有的波长调度算法有更好的性能。     

基于预留的802.16MAC层资源调度算法

提出了一种IEEE802.16系统中基于预留的MAC层资源调度方法,可以有效的解决IEEE802.16系统中高优先级业务过多占用优先级业务带宽而带来的不公平性问题。仿真结果表明,与原有资源调度算法相比,这种算法能够在满足各种业务对QoS要求的同时,具有更好的公平性和更高的带宽利用率。     

一种基于网格划分的有向传感网时空覆盖调度算法

针对有向传感器网络中的时空覆盖调度问题进行研究,从有向传感器节点感知模型出发,设计了基于网格划分的网络基本区域生成方法,在此基础上提出了节点最大覆盖调度迭代选择MaxGreedy算法.通过仿真实验验证了网格划分方法的有效性,设计了一系列的时空覆盖算法对比实验,深入评估MaxGreedy算法的性能.对比试验结果表明,MaxGreedy算法可以高效地生成网络的节点调度模式,并在一定程度上提高网络的时空覆盖率.     

基于双向拍卖的网格资源预留机制研究

针对网格资源预留的需求和已有资源预留模型存在的问题,给出了适合网格系统的资源预留模型。根据网格资源和双向拍卖的特点,提出了基于双向拍卖的网格资源定价策略,并设计了详细的拍卖算法。最后,模拟实验结果证明了该机制的有效性和正确性。     

基于遗传算法的网格任务调度研究

网格调度是一个典型的NP问题,研究表明遗传算法是解决复杂环境下资源调度的有效方法之一。针对异构环境下的网格任务调度,提出了一种改进的遗传算法,并改进了遗传算法的收敛特性,通过分析实验结果证明该算法优于传统的调度算法。     

Performance Evaluation of Resource Reservation Policies for Rate-Controlled Earliest-Deadline-First Scheduling in Multi-Service Packet Networks

The paper addresses the issue of reserving resources at packet switches along the path of flows requiring a deterministic bound on end-to-end delay. The switches are assumed to schedule outgoing packets using the Rate-Controlled Earliest-Deadline-First (RC-EDF) scheduling discipline. EDF is known to be an optimal scheduling discipline for deterministic delay services in the single scheduler case. We propose a number of static and dynamic reservation policies for mapping the end-to-end delay requirement of a flow into local delay deadlines to be reserved at each scheduler. These policies are based on non-even resource reservation where the resources reserved depend on the capacities and loading at each node in the network. We define and prove the optimality of a certain non-even policy for the case of a single path network with homogenous static traffic. We present extensive simulation results for different scenarios which show that dynamic non-even resource reservation provides superior performance when compared to simple policies such as even dividing of end-to-end delay among the schedulers.     

无线网格资源调度优化策略

文中提出了一种基于改进GEAR算法的无线网格资源调度算法.它通过引入Q-learning机制,使传感节点具有网络负载平衡的功能,降低了节点的能量损耗,延长了无线传感器网络的生命周期.实验结果表明,该算法在具有较优调度性能的前提下,有效地提高调度的工作效率.     

无线网络中基于多用户分集的机会调度研究

机会调度(Opportunistic Scheduling,OS)是对无线衰落信道通信的一种现代认识观点。与基于链路/速率自适应的方案不同,机会调度利用无线信道的时空变化特性来提高无线通信系统的性能,而不是减轻它的影响。本文介绍一种引入了业务流参数的机会调度方案,可以保证调度的公平性,并满足不同类型业务流的QoS(Quality of Service)要求。在瑞利衰落信道中的研究数据显示,采用机会调度达到的系统吞吐量要优于轮询(Round-Robin,RR)方案的吞吐量,并保证了不同等级业务流之间的公平性。     

Performance Study of Distributed Wavelength Reservation Protocols within Both Single and Multi-Fiber WDM Networks

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.     

基于改进遗传算法的网格资源调度算法

网格计算关注大规模的资源和任务调度，要求采用的调度算法能够具有高效性。提出一种基于改进遗传算法的资源调度算法，该算法综合考虑了资源任务分配量以及任务完成时间，从而设计出良好的交叉和选择算子，既能够保留完成时间比较小的个体又能够保留具有一部分优秀资源分配方式的个体．算法具有较好的效率和收敛性。     

基于Min-Min改进后的网格调度算法

根据现有网格计算中的任务调度算法,深入分析了传统的Min-Min算法,指出该算法中存在的负载不平衡的缺陷.针对这一缺陷,提出改进算法Sect-Min,该算法采用"分段"的思想,把任务分成若干小任务后再分别进行调度.使用Matlab进行模拟仿真,结果证明了改进后算法的合理性和有效性.     

Multi-Layer Lambda Grid With Exact Bandwidth Provisioning Over Converged IP and Optical Networks

This paper proposes for the first time a multi-layer Lambda Grid, which is a platform to establish dynamically a computing environment with a guaranteed level of throughput and bandwidth over converged IP and optical networks according to each client reservation request. It enables client-side visualization of a computing environment comprising converged IP and optical networks and geographically distributed computing domains. In addition, it dynamically reserves a packet switched path/tunnel (sub-lambda) with the exact requested bandwidth and computer resources according to each client reservation request. Moreover, it links the reserved path to the reserved computers, controls the reserved sub-lambda and the relevant lambda as needed, and routes only the reserved packet flow between the reserved computers to the reserved sub-lambda. In terms of cost performance and bandwidth flexibility, it can use network resources more effectively than existing Lambda Grids. Through the multi-layer Lambda Grid, clients can execute applications in an established computing environment as if the environment was a virtual private computing environment for clients. To achieve the multi-layer Lambda Grid, this paper also proposes a novel technology. This technology dynamically reserves a sub-lambda with the exact requested bandwidth according to each client reservation request. Moreover, it links the reserved sub-lambda to the reserved computers, and controls the reserved sub-lambda and the relevant lambda as needed. In addition, it routes only the reserved packet flow between reserved computers to the reserved sub-lambda. To evaluate the feasibility of the technology, a common computing environment with the multi-layer Lambda Grid for scientific calculation, file transfer, and high-definition video streaming services is presented in an actual field environment. Through this experiment, the total feasibility of the multi-layer Lambda Grid is shown.     

一种基于休眠调度策略的无线传感网络分簇协议

文中设计了一种基于休眠调度策略的无线传感网络分簇协议.该协议计算出簇首最佳比例和网络瞬时剩余能量,采用固定簇首数目与剩余能量估计的方法对网络进行分簇,在成簇后的数据传送阶段采用蚁群算法计算出节点的唤醒概率,最后通过仿真实验与LEACH、SEP协议进行了比较.实验结果表明:该协议在对目标保持较好探测效果的前提下能更均匀的消耗网络的能量,从而延长网络的生命周期.     

基于蚁群优化算法的网格OBS任务调度研究

本文采用蚁群优化算法（ACO）设计了基于光突发交换（OBS）网络的网格任务调度。该算法既考虑了网格用户的需求,同时结合了网格中计算资源和网络资源的分配。设计了基于ACO算法的两种通路选择规则,并在一个集中式的网格OBS仿真平台上对这两种选路规则的性能进行了对比分析。     

Integrated Scheduling of Grid Applications in WDM Optical Light-Trail Networks

A novel task graph model, flexible task model (FTM), is proposed for modeling the grid computing tasks and the relationships among the tasks. In this model, a task may generate output before the task completes whereas previous work assumes that no output is available until the task is completed. In addition, a task in FTM can start to execute when it has collected a minimum amount of required input from its predecessors. FTM is more general and flexible than the conventional task graph model considered in previous work. Based on FTM, we investigate the problem of scheduling grid applications that integrates the resource allocation for task execution and service provisioning for subwavelength data communication between the tasks. Data communication between grid tasks under the FTM model is better supported using light-trails in wavelength division multiplexing (WDM) networks, than lightpaths. The objective is to minimize the total amount of time for task completion or makespan. Simulation results show that our proposed scheduling algorithm under FTM significantly reduces the total task completion time compared with that under the conventional task graph model. Moreover, the communication service provisioning using light-trails is very resource efficient.      

基于多属性QoS约束的网格资源调度算法研究

本文以Min-Min调度算法为基础,以提高调度过程中的用户满意度为目的,提出了改进的Min-Min算法DQ(double QoS).在DQ算法的基础上,采用进一步细化QoS参数和划分任务权值的方法,设计了多属性QoS约束的调度算法(multi-QoS constraints scheduling algorithm,MQCSA).该算法通过选取任务的完成期限和网络带宽属性以及完成任务所需的CPU参数,有效地解决了不能预期完成的任务占用网格资源的问题.采用GridSim工具包模拟了相关的调度算法,验证了DQ算法和MQCSA的效率.     

A 802.11 Based Slotted Dual-Channel Reservation MAC Protocol for In-Building Multi-Hop Networks

In this paper, we propose a novel slotted Dual-Channel Reservation (DCR) MAC protocol that uses 802.11 primitives for providing both Quality of Service (QoS) and fairness. RTS/CTS handshaking is transmitted on a separated control channel to prevent successive collisions of RTS and CTS packets with existing data transmission. Furthermore, contention for channel access may be initiated by sender as well as receiver depending on the channel status for better fairness. A simple slot reservation algorithm in the data channel provides high efficiency. The main conclusion is that reservation access benefits both delay performance, and efficiency as well as fairness—the reason being that not only an exposed terminal can regain the channel more easily because of dramatically reduced contention (RTS-CTS) traffic, but also a hidden terminal receives less collisions in handshaking since any node winning a slot will quit contending on the control channel. Therefore, it is highly recommended to use reservation access even if the prevailing traffic is data, e.g. TCP. To enhance delay performance, we devise a fake packet repeating mechanism that can reserve the slot for a connection even if the user temporarily has no packets to transmit. Simulations based on key metrics—throughput, fairness index and mean delay are performed to validate the new protocol and quantify its advantages. The limitations of the proposed DCR-802.11 protocol due to need for global clock synchronization and dual channels are also discussed.Jing Zhu received the B.S. and M.Sc. degrees both in electronic engineering from Tsinghua University, Beijing, P. R. China, in 2000 and 2001, respectively, and Ph.D. in electrical engineering from University of Washington (Seattle) in 2004. Currently, he is a research scientist in the Communications Technology Lab at Intel Corp. He is an IEEE member. His main research interest is high-performance wireless networking and its applications, e.g. Internet-on-Move, Digital Home, and Intelligent Transport System, focusing on cross-layer protocol optimization.Sumit Roy received the B. Tech. degree from the Indian Institute of Technology (Kanpur) in 1983, and the M. S. and Ph. D. degrees from the University of California (Santa Barbara), all in Electrical Engineering in 1985 and 1988 respectively, as well as an M. A. in Statistics and Applied Probability in 1988. His previous academic appointments were at the Moore School of Electrical Engineering, University of Pennsylvania, and at the University of Texas, San Antonio. He is presently Prof. of Electrical Engineering, Univ. of Washington where his research interests center around analysis/design of physical and data link layer of communication systems, with a topical emphasis on next generation mobile/wireless networks. He is currently on academic leave at Intel Wireless Technology Lab working on high speed UWB radios and next generation Wireless LANs. His activities for the IEEE Communications Society includes membership of several technical committees and technical program committees for conferences, and he serves as an Editor for the IEEE Transactions on Wireless Communications and Wiley Journal on Wireless Communications and Mobile Computing.     

Distributed Control Protocols for Wavelength Reservation and their Performance Evaluation

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.