一种适用于多业务场景的HSDPA分组调度算法

针对HSDPA多业务应用场景,提出一种新的分组调度算法。该分组调度算法在保证每种业务的QoS的同时,兼顾公平性和分组时延限制。在包含流类、交互类以及背景类业务的应用场景里对该算法进行仿真。仿真结果表明,与正比公平和M-LWDF算法相比,该算法能获得更好的系统性能。     

A genetic approach for downlink packet scheduling in HSDPA system

High speed downlink packet access (HSDPA) system currently under development in 3rd generation partnership project (3GPP) [1] employs number of parallel shared channels and adaptive modulation and coding scheme (MCS) to enable a high rate packet data transfer from base station (Node-B) to user equipment (UE). To decide how to share the available radio channel capacity amongst the active UEs, a packet scheduling and channel assignment algorithms are employed at Node B. Packet scheduling techniques such as max carrier to interference ratio (C/I) or round robin (RR) fails to take into account all the aspects of the quality of service (QoS) provisioning. In this paper, the fundamentals genetic algorithms and conventional wireless scheduling techniques are combined and the weaknesses of the existing known techniques are exploited to propose a novel hybrid genetic packet scheduler (HGPS) for the HSDPA system. A combination of random and intelligent diversity of population and comparative nature of the selection process of genetic engine contribute to its robustness. The proposed HGPS outperforms Max C/I packet scheduler in terms of total delivered throughput within low delay thresholds. Unlike conventional packet scheduling technique HGPS does not rely only on the current or past status of the scheduling process. By treating the possible solutions as points in a search space, the proposed HGPS through a genetically guided search visits and examines the possible solutions and estimates the impact of each these solution on overall performance of system in terms of fairness, throughput or QoS without actually performing a transmission. Subsequently, the solution that achieves the best estimated overall performance is chosen for the actual transmission. By means of computer simulation, performance of the HGPS algorithm is characterized in Rayleigh fading and shadowing radio channel conditions. The impact of imperfect reporting on the performance of HSDPA system is evaluated. We examine the joint impact of reporting latency, imperfect channel estimation and the corruption of reports in the feedback channel on the performance. It is shown that the proposed class of intelligent parallel random schedulers is highly robust against the imperfect reports from UEs. Acknowledgment The authors would like to acknowledge the valuable assistance provided by Mr Pierre Coulon of Fujitsu Laboratories of Europe Ltd.This work was presented in part at IEEE WPMC’2002, and will be presented in part at IEEE IST’2003.     

基于多QoS约束的网格任务调度算法

提出一种基于QoS的网格资源管理模型和此模型下基于多QoS约束的网格任务调度算法。引入效益函数对QoS描述建模,为网格任务调度算法提供合理的优化目标。在此基础上改进传统调度算法得到基于多QoS约束的调度算法。实验表明,改进后的算法有更好的性能,更适合应用于网格环境中。     

无线传感器网络服务质量的随机控制策略

为使网络具有给定的感知范围或覆盖率,必须保证WSN传感器具有一定空间密度,因此网络中活动的传感器数量可作为QoS的一种度量[1]。在这种定义下,提出两种QoS控制方法,基于贪心算法的集中式控制方法和基于寿命的分布式随机控制方法。如果传感器能够存储运行状态信息或每隔一段时间能够交换节点寿命信息,前者可以获得最优的网络寿命;后者则通过交换初始传感器节点寿命,利用平均寿命信息随机调度活动的节点,从而延缓存活节点数的降低。仿真结果证实了这两种方法的有效性。     

融合DE和NSGA-Ⅱ算法的网格工作流调度研究*

针对当前网格工作流调度算法中大多只考虑DAG结构的网格工作流、考虑QoS维数较少及将多QoS参数聚合成一个单目标函数进行优化调度的现状,基于AGWL网格工作流模型,提出了一种带QoS约束的多目标优化的网格工作流调度算法,该算法是将DE的变异和交叉算子替换NSGA-Ⅱ中的变异和交叉操作所设计的一种调度算法。通过与基于NSGA-Ⅱ的网格工作流调度算法比较,表明了该算法的有效性。     

DBC性价比资源调度算法

传统的DBC（Deadline and Budget Constrained）调度算法,比如时间最优调度算法、代价最优调度算法都是在时间（deadline）和代价（budget）的约束下,满足时间或代价单方面的QoS需求的极端情况。针对这一不足,提出了一种基于DBC的性价比资源调度算法,综合考虑了时间和代价的QoS需求,目的在于提高任务的完成量以及任务完成的性价比,并通过推理论证和仿真实验验证了该算法的有效性和优越性。     

多QoS约束的双目标最优的网格工作流调度研究*

针对当前网格工作流调度算法中大多只考虑DAG结构的网格工作流,涉及QoS参数较少或将多QoS参数聚合成一个单目标函数进行优化调度,提出了一种多QoS约束的双目标最优的网格工作流调度算法。该算法是基于AGWL网格工作流模型和改进的MOPSO算法,其目标是在满足可靠性、可利用性和声誉这三维QoS参数约束下,同时最小化两个冲突目标,即响应时间和服务费用。通过与原MOPSO所设计的网格工作流调度算法比较,该算法能获得更优的优化解。     

多QoS约束的层次多播路由算法框架

为了解决网络路由的扩展性问题。大型网络通常被划分成若干个不同的域。拓扑聚集是对这些域的拓扑状态信息进行汇总的过程。在拓扑聚集的基础上，QoS层次多播路由算法用来构造满足QoS要求的域闻多播树。现有的QoS层次多播路由算法在其拓扑聚集和路径计算的过程中都只考虑了存在两个QoS特征值的情况。本文提出了一种具有多QoS约束的层次多播路由算法框架HMRMQ（Hierarchical Multicast Routing with Multiple QoS constraints），此算法框架不仅为基于多QoS特征值的拓扑状态聚集和状态信息表示提供了新的方法，而且提出了一种适应于多QoS约束的层次多播路由新算法。我们提出的状态信息表示法和拓扑聚集算法都具有很好的扩展性，分布式的路由算法也便于某些安全性策略的实施。理论分析和实验结果不仅证明了HMRMQ的正确性和有效性，同时也表明了HMRMQ在网络路由的扩展性、路由成功率、网络代价以及报文负载等方面都具有良好的性能。     

基于HSDPA混合群集智能算法的多用户调度

传统的基于粒子群最优化的混合启发式算法和模拟退火算法往往以牺牲解的质量或者求解速度来实现有效的调度,为了解决这一问题,提出了一种基于高速下行分组接入（HSDPA）标准的混合群集智能算法。首先假定HSDPA标准所指定的是现实性不完善的信道状态信息（CSI）反馈,并以有限集合的形式存在于信道指示符（CQI）中;接着在最优化过程中,利用模拟退火算法和粒子群最优化算法各自的优点设计混合群集智能算法;最后利用混合算法进行数据处理,得到最优解的同时降低了复杂度,从而实现提升系统通量,达到调度最优化的目的。实验结果表明,与传统的基于粒子群最优化的算法相比,所提的混合算法取得了更好的调度效果。     

Effective Capacity and QoS for Wireless Scheduling

Multiuser scheduling in a wireless context, where channel state information is exploited at the base station, can result in significant throughput gains to users. However, when QoS constraints are imposed (in the form of overflow probabilities), the benefits of multiuser scheduling are not clear. In this paper, we address this question for independent and identically distributed ON-OFF channel models, and study a ldquomultiuserrdquo formulation of effective capacity with QoS constraints. We consider a channel-aware greedy rule as well as the channel-aware max-queue rule, and showed that these algorithms that yield the same long-term throughput without QoS constraints have very different performance when QoS constraints are imposed. Next, we study the effective capacity for varying channel burstiness. From results on multiuser scheduling, we expect the long-term throughput to grow with increasing channel burstiness. However, we show that the throughput with QoS constraints decreases with increasing channel burstiness. The intuitive justification for this is that with increasing burstiness, even though the the long-term throughput increases, the channel access delay increases as well resulting in poor QoS performance.     

一种基于遗传算法的QoS组播路由算法*

通过考虑组播通信服务质量需求与网络资源约束,研究了基于服务质量的组播路由选择算法问题,提出了一个基于遗传算法来构造满足QoS需求的组播路由树算法。通过仿真研究,证实了该算法的可行性、有效性及健壮性。同时,对遗传算法参数与算法性能之间的关系进行了讨论。     

IEEE 802.16中改进的QoS调度算法设计

IEEE802.16标准在每个节点处都提供实时业务和非实时业务。由于基于优先级的业务的服务质量（QoS）的需求不同,因此需要对传统的调度算法进行改进使其具有更大的适应性。为了改善QoS端到端时延的性能,提出了一种混合调度算法（EDD和WFQ算法相结合）。仿真结果表明：在每个节点处,提出的混合算法比仅使用EDD算法能给实时业务产生的时延更少,并且还能够使单个BS在可允许的端到端时延范围内容纳数量更多的子SS,而且使用从BS到SS的GPSS模式的调度机制比使用GPC模式能产生更小的时延。     

Multi-Dimensional Scheduling for Real-Time Tasks on Heterogeneous Clusters

Multiple performance requirements need to be guaranteed in some real-time applications such as multimedia data processing and real-time signal processing in addition to timing constraints.Unfortunately,most conventional scheduling algorithms only take one or two dimensions of them into account.Motivated by this fact,this paper investigates the problem of providing multiple performance guarantees including timeliness,QoS,throughput,QoS fairness and load balancing for a set of independent tasks by dynamic ...     

考虑邻域结构动态调整的多星应急调度算法

实际应用中的卫星调度方案往往受到外界因素的影响,例如电磁干扰、卫星失效、云层遮挡以及新任务的动态到达等,需要在短时间内对原始调度方案进行调整并生成新的调度方案,以保证卫星系统的稳定性.对此,考虑新任务到达情况下的卫星应急调度,建立多星协同应急调度的整数规划模型,并提出一种基于动态邻域结构的卫星应急调度算法(satellite emergency scheduling algorithm based on dynamic neighborhood, SESA-DN).设计多种类型的邻域结构以及动态的邻域选择策略,能够根据任务完成情况进行有效反馈,通过对应急任务的插入与替换生成卫星应急调度方案;同时,构建多星应急调度场景,通过大量仿真实验将SESA-DN算法与多种对比算法进行比较.实验结果表明, SESA-DN算法的稳定性优于对比算法,对于多星协同动态调度问题具有很好的适用性.     

VANET QoS-OLSR: QoS-based clustering protocol for Vehicular Ad hoc Networks

In this paper, we address the problem of clustering in Vehicular Ad hoc Networks (VANETs) using Quality of Service Optimized Link State Routing (QoS-OLSR) protocol. Several clustering algorithms have been proposed for VANET and MANET. However, the mobility-based algorithms ignore the Quality of Service requirements that are important for VANET safety, emergency, and multimedia services while the QoS-based algorithms ignore the high speed mobility constraints since they are dedicated for Mobile Ad hoc Networks (MANETs). Our solution is a new QoS-based clustering algorithm that considers a tradeoff between QoS requirements and high speed mobility constraints. The goal is to form stable clusters and maintain the stability during communications and link failures while satisfying the Quality of Service requirements. This is achieved by: (1) considering the high mobility metrics while computing the QoS, (2) using Ant Colony Optimization for MPRs selection, and (3) using MPR recovery algorithm able to select alternatives and keep the network connected in case of link failures. Performance analysis and simulation results show that the proposed model can maintain the network stability, reduce the end-to-end delay, increase the packet delivery ratio, and reduce the communications overhead.     

一个市场驱动的QoS网格工作流任务调度算法

网格调度关系到整个网格任务运行的效率,因此在网格的研究过程中,已经提出了很多调度算法.但这些算法大部分是对元任务(Meta-task)进行调度,很少是针对关联任务的.在考虑用户QoS(Quality of Service)需求的情况下,提出了一个市场驱动的QoS网格工作流任务调度算法.仿真实验结果表明了该算法的合理性和有效性.     

An End-to-End Embedded Approach for Multicast/Broadcast of Scalable Video over Multiuser CDMA Wireless Networks

We investigate an embedded multicast/broadcast approach for transport of digital video over spread-spectrum code-division multiple access (CDMA) cellular networks. Previous work has shown that the incorporation of a scalable source coding scheme with multiresolution modulation provides a promising design paradigm for the practical realization of the information-theoretic performance predictions originally developed by Cover, which demonstrated that optimal multicast/broadcast performance could be achieved by an embedded transmission scheme. Hence, the major technical challenge associated with the design of an end-to-end embedded multicast/broadcast system is how to match an embedded modulation constellation with a scalable source coding scheme. In this work, taking into consideration both the interference-limited and bandwidth-limited characteristics of a CDMA system, we provide a cross-layer approach incorporating adaptive power allocation and channel coding strategies and effectively match a discrete cosine transform based scalable motion-compensated video encoder to an embedded multiresolution modulation scheme to simultaneously deliver a basic quality-of-service (QoS) to less capable receivers while maximizing both the QoS for more capable receivers and the system capacity. We demonstrate the efficacy of this approach using the ITU-T H.263+ video scalable hybrid coder, although the approach is generally extensible to other scalable coding schemes as well     

A multiuser simulation system for video transmission over HSDPA

With the explosive growth of multimedia applications, video transmission over HSDPA networks has attracted more and more attentions. Particularly in the last few years, lots of special transmission schemes have been proposed to improve the end-to-end qualities of mobile video applications. However, due to lack of a common video delivery simulation platform over HSDPA networks, the researchers have met obstacles in evaluating and comparing the performance of these schemes in a unified simulation environment. To fill this gap, a common system-level video transmission simulation platform is proposed in this paper, which is implemented specially for the HSDPA networks. To the best of our knowledge, this platform is the first one in integrating the video encoder/decoder, the video quality evaluator and the HSDPA simulator together. In this way, the researchers can study and analyze not only the overall system performance of the video-aware cross-layer transmission solutions, but also explore the influence and interaction of those separate sub-layers in the HSDPA wireless networks, such as the video application-layer, the transmission control layer, the HSDPA MAC layer, and the physical layer. Moreover, to test and verify our simulation platform, we implement eight representative fast scheduling algorithms over the HSDPA networks, and evaluate their transmission performances for the H.264/AVC video applications. Experimental simulation results demonstrate the effectiveness and rationality of our simulation system.     

分时EDF算法及其在多媒体操作系统中的应用

提出了一种新的CPU调度算法－－分时EDF（Earliest Deadine First)算法,该算法能保证硬实时任务不丢失死线,并易于在分时系统中实现。以分时EDF算法为基础,提出一种新的CPU层次调度算法－－HRFSFQ,该算法用于多媒体操作系统时能保证各类任务的QoS。最后通过大量实验证明了上述算法的有效性和正确性。     

QoS-adaptive bandwidth scheduling in continuous media streaming

In this paper, we present a QoS-adaptive admission control and resource scheduling framework for continuous media (CM) servers. The framework consists of two parts. One is a reserve-based admission control mechanism in which new streams, arriving during periods of congestion, are offered lower QoS, instead of being blocked. The other part is a scheduler for continuous media with dynamic resource allocation to achieve higher utilization than non-dynamic schedulers by effectively sharing available resources among contending streams and by reclamation which is a scheduler-initiated negotiation to reallocate resources among streams to improve overall QoS. This soft-QoS framework recognizes that CM applications can generally tolerate certain variations on QoS parameters; that is, it exploits the findings about human tolerance to degradation in quality of multimedia streams. Using our policy, we could increase the number of simultaneously running clients that could be supported and could ensure a good response ratio and better resource utilization under heavy traffic requirements. Our admission control and scheduling strategy provides three principle advantages over conventional mechanisms. First, it guarantees better total system utilization. Second, it provides better disk utilization and larger admission ratio for input CM streams, which is a major advantage. Third, it still presents acceptable play-out qualities compared to the conventional greedy admission control algorithm.