Ad hoc网络中分组调度算法研究

本文概述了Ad hoc网络及其特点、结构等;阐述了有线网络的分组调度算法在Ad hoc网络中的局限性;重点介绍了几种现有的典型Ad doc网络的分组调度算法。     

双服务器分组调度算法

分组调度算法对于确保分组交换系统的QoS具有重要意义。时延,公平性,计算复杂度是微量分组度算法的主要指标。本文提出了一种双服务器分组调度算法,该算法在两种不同的工作状态下分别采用两种服务规则决定分组的服务次序。其中一种服务规则用来确保分组的时延,另一种服务规则在时延得到保障的情况下对系统的公平性进行改善,这两种规则计算都不复杂。因此本文提出的算法具有时延低,公平性较好,计算复杂度低的特点。     

应用网络编码的分组交换调度算法

网络编码理论与交换调度算法相结合重点是实现在联合输入输出排队（CIOQ）交换结构中提供组播服务。文章证明了对一个流中的分组进行线性网络编码可以承载不允许网络编码时不能够承载的交换流量模式,也就是说,网络编码允许CIOQ交换结构在实现组播服务时有更大的速率区域,并给出了基于图论方法的描述。运用增强冲突图的稳定集多面体等概念,文章证明了计算离线调度的问题可以简化成某种图染色问题,同时,也针对组播调度提出了一个称之为最大权重稳定集的在线调度算法。     

一种基于帧的快速包调度算法

本文提出了基于帧的近似排序包调度新算法（FASFQ），该算法用帧排序代替传统的包排序来处理G连接（预约带宽的连接）数据，并在帧与帧之间的空隙传送E型（best offort型）数据。理论分析和实验结果都表明，FASFQ算法与传统算法相比，在大大降低了排序复杂的同时，还能为G连接提供预约带宽，保证连接的独立性和公平性，避免E连接对G连接的冲击。     

分组交换网络中虚拟时钟调度算法研究

基于虚拟时钟的算法在实现对资源进行公平分配的同时具备良好的可扩展性，从而能够满足QOS控制中对于分组调度算法的需求。本文主要对一些基于虚拟时钟的调度算法进行了分析和讨论，这也是进行QOS控制研究的基础。     

无线网络中的分组调度算法

探讨了将有线网络的分组调度算法引入无线网络需要改进的事项,分析了公平排队算法,建立了一个基本的无线分组调度模型,并综述了一些目前存在的无线分组调度算法。     

GPRS中分组调度算法

主要讨论通用无线分组业务（GPRS）调度算法。首先介绍了一些常用分组调度算法，给出了GPRS中服务质量（QoS)定义和GPRS中选择分组调度算法原则，并根据对GPRS特性和三种算法性能的分析与比较，提出了一种新的基于延迟约束分组调度算法。通过仿真发现，新算法可在满足延迟要求基础上以较小复杂度获得比其余算法更高的资源利用率。     

Clos网络中变长分组交换及调度算法研究

Clos网络是多端口的路由器和交换机中经常采用的交换网络,其优点在于它是一个结构全对称的网络。比较了多级Clos网络分布式调度算法中定长分组和变长分组交换的特点;给出一种基于变长分组交换的MSM型三级Clos交换网络结构和相应的ACBS调度算法;消除了分组负载分配的不公平性。分析表明该调度算法优于传统算法,并通过仿真实验验证了算法的有效性。     

分布式基站中分组调度算法的研究

本文简要介绍了分布式基站及现有分组调度算法的发展概况,主要探讨并分析了常见的几种无线分组调度算法的适用性及其存在的问题,并且进行了仿真分析,最后指出了分布式基站中分组调度算法的发展方向。     

分布式基站中分组调度算法的研究

本文简要介绍了分布式基站及现有分组调度算法的发展概况,主要探讨并分析了常见的几种无线分组调度算法的适用性及其存在的问题,并且进行了仿真分析。最后指出了分布式基站中分组调度算法的发展方向。     

分组交换网络中队列调度算法的研究及其展望

本文主要讨论分组交换网络中的队列调度算法,对现有的调度算法进行了分类和比较研究,分析了其性能指标和技术特点,最后结合我们的相关研究工作讨论了未来的发展趋势并给出了有待研究的一些课题.     

Robust Packet Scheduling in Wireless Cellular Networks

This paper addresses the following robust scheduling problem: Given that only coarse-grained channel state information (i.e., bounds on channel errors, but not the fine-grained error pattern) is available, how to design a robust scheduler that ensures worst-case optimal performance? To solve this problem, we consider two coarse-grained channel error models and take a zero-sum game theoretic approach, in which the scheduler and the channel error act as non-cooperative adversaries in the scheduling process. Our results show that in the heavy channel error case, the optimal scheduler adopts a threshold form. It does not schedule a flow if the price (the flow is willing to pay) is too small, in order to maximize the system revenue. Among the scheduled flows, the scheduler schedules a flow with a probability inversely proportional to the flow price such that the risk of being caught by the channel error adversary is minimized. We also show that in the mild channel error model, the robust scheduling policy exhibits a balanced trade-off between a greedy decision and a conservative policy. The scheduler is likely to take a greedy decision if it evaluates the risk of encountering the channel error adversary now to be small. Therefore, robust scheduling does not always imply conservative decision. The scheduler is willing to take “risks” to expect higher gain in some scenarios. Our solution also shows that probabilistic scheduling may lead to higher worst-case performance compared to traditional deterministic policies. Finally, the current efforts show the feasibility to explore a probabilistic approach to cope with dynamic channel error conditions.     

Class-Based Packet Scheduling to Improve QoS for IP Video

An important issue for video transmission over IP networks is the preservation of perceived video quality despite packet loss. Packet loss can be detrimental to compressed video. However, reducing packet loss to a very low level is difficult with current techniques. Furthermore, even a very low objective loss probability can still seriously distort perceived video quality. This paper presents a packet scheduling scheme at a router which addresses the loss issues of networked video. Experiments using real video data show that the proposed scheme can significantly improve the visual quality of video and network efficiency. Moreover, it can provide different classes of videos with different levels of loss guarantees, while maintaining service fairness among the same class of videos.     

认知无线电网络中基于包调度算法的主动频谱切换

认知无线电网络中,主用户出现在自己的授权频段,但被次用户占用,此时次用户进行频谱切换.主动频谱切换机制是一种可以提高网络的带宽利用率,同时降低丢包率的方法.基于一个有效的包调度算法,提出一个主动频谱切换机制,以期减少频谱切换发生时的不可用信道.该包调度算法有效地集成了两个算法:频谱空洞填充算法和包迁移算法,来减少丢包率和带宽碎片.实验仿真结果验证了该主动频谱切换机制的有效性.     

分组交换机的极大匹配调度算法仿真与比较

对于输入缓存类型的分组交换系统,调度算法是交换系统的关键技术之一,其性能直接影响着交换单元的性能。研究了几种典型的极大匹配调度算法:PIM,iSLIP,FIRM和输出串行调度算法。通过OPNET构造了一种调度算法模型,以8×8 crossbar交换结构为例,基于该模型对这几种极大匹配调度算法进行了仿真。根据仿真结果从平均调度时延等性能指标及实现复杂度方面进行了分析和比较,指出了现有算法的优缺点,并提出了进一步改进的方向,对卫星ATM/IP交换系统的研究与设计具有指导作用。     

An Efficient Scheduling Discipline for Packet Switching Networks Using Earliest Deadline First Round Robin

This paper addresses a frame-oriented scheduling discipline, EDF-RR (earliest deadline first round robin), for OQ (output-queued) switch architecture and data traffic consisting of fixed-length cells. Bandwidth reservation for an active session is performed by holding a number of cell slots for the session in a repeatedly-transferred frame. Each cell that is going to be transferred in the frame is assigned a virtual release time and a virtual deadline according to the bandwidth reservation scheme. The transmitting order of the cells in the frame is determined by non-preemptive non-idling EDF algorithm so that cells of a backlogged session in the frame are distributed as uniformly as possible. Through the analysis applying real-time scheduling theory and network calculus as well as network simulation, EDF-RR takes the advantage of O(1) computational complexity, and possesses tight delay bounds and lenient buffer requirements. The proposed scheduling discipline is appropriate for distributed real-time systems as we show that sessions can be configured based on message traffic models and deadline requirements. Also, a modified version of EDF-RR, called EDF-DRR, can be applied as traffic regulator when jitter requirements exist among active sessions. This work was sponsored in part by the Federal Aviation Administration (FAA) via grant DTFA03-01-C-00042. Findings contained herein are not necessarily those of the FAA.     

分组调度算法的仿真与分析

介绍了现有分组调度算法的发展概况，主要探讨并分析了常见的几种无线分组调度算法的适用性及其存在的问题，并且对分组调度算法进行了仿真和分析．最后指出了分组调度算法的发展方向．     

一种适用于宽带无线城域网实时业务的分组调度算法

对宽带无线城域网（WMAN）而言,分组调度算法是保证用户服务质量（QoS）、平衡用户间公平性的关键。在研究比例公平调度算法（PF）算法与修正的最大加权时延优先算法（M-LWDF）的基础上,一种新的适用于宽带无线城域网实时业务的分组调度算法被提出,此算法引入了新的衡量服务队列负载的信息,能够实时地更新状态参数,提高了系统性能。仿真结果表明,此算法在保证系统吞吐量的同时,比M-LWDF算法具有更好的时延特性和公平性。     

基于VirtualClock调度算法的接入允许控制算法

本文针对于Virtual Clock调度算法提出了一种基于生存期的接入允许控制算法.原有Virtual Clock的接入允许控制算法没有考虑到系统中在有连接建立和拆除的情况下如何动态分配带宽,致使分组的时延无法确保.本文从Virtual Clock算法的参考模型出发,对带宽释放和分配的时机作出规定.理论分析和仿真结果表明,本文的算法能够保证Virtual Clock算法的时延特性.本文的思路对于其他调度算法的接入允许算法也具有参考意义.