基于局部近似过滤的多约束服务选择方法

随着Web服务数量与用户需求的不断增长,如何在功能约束和QoS约束下选择Web服务去构建高质量的组合服务已成为Web服务领域的一项重要研究内容。然而,现有大多数Web服务选择方法仅仅解决了在多种QoS约束下选择服务的问题,忽略了服务间的功能性约束。为解决这一问题,该文提出一种基于局部近似过滤的多约束服务选择方法。该方法首先利用候选服务在多种约束下的被选关系,滤除部分不满足约束的服务,并估算每个剩余候选服务的局部适应度;然后,利用文中设计的有向粒子群算法,以候选服务的局部适应度为引导信息搜索出最优方案。实验结果表明了方法的有效性。     

多光纤WDM网中支持QoS的波长重路由算法

在WDM网上，波长连续性限制会降低网络的信道利用率，增加光路建立请求的阻塞率。采用波长重路由技术可以减少波长连续性限制对网络性能的影响。该文采用波长图模型，对多光纤WDM网中支持QoS的波长重路由算法进行了探讨，提出一种支持QoS的波长重路由算法－－动态选择法，并采用两种网络模型，在不同负载的动态业务下对所提算法进行了仿真研究；仿真结果表明所提算法既满足了上层业务不同的QoS要求，同时又充分利用了有限的网络资源，使全网的平均阻塞率降低。     

一种基于多QoS注册中心和模型异构的WEB服务选择算法

多QoS注册中心并且QoS模型异构给服务选择带来巨大困难。借鉴多属性群决策(MAGDM)理论的基本思想,该文提出一种解决上述难题的多注册中心和模型异构的Web服务选择算法(MRHQ_WSSA)。MRHQ_ WSSA算法能综合评估各QoS注册中心的QoS信息,从而获得QoS综合最优的服务组合计划。MRHQ_WSSA算法包括5个步骤：用户偏好规格化、群偏好确定、加权规格化决策矩阵、确定群理想方案、计算群贴近度。最后通过实验验证算法的优势和有效性。     

一种用于解决OBS网中资源竞争的新机制

综合考虑多种因素,对突发的偏置时间进行改进,提出了一种新的解决资源竞争并能提供服务质量(QoS)保证的机制.结合3种信道调度算法(LRU、FF和PS),对该机制进行了仿真,并与PPJET机制进行了对比,结果表明,在突发丢失方面该机制的性能明显优于后者.     

基于ZigBee协议的无线传感器网络服务质量的研究

针对于无线传感器网络的发展,以及新型的协议规范ZigBee协议在无线传感器网络中广泛应用,以分析研究基于ZigBee协议的无线传感器网络的服务质量的评价机制为目的。通过对无线传感器网络及ZigBee协议的组成、通信特点的研究,以及结合传统网络的QoS评价机制,最终总结得到可以从5个方面来评价ZigBee协议的无线传感器网络的服务质量。     

A USER－DEPENDENT PERFECT－SCHEDULING MULTIPLE ACCESS PROTOCOL FOR VOICE－DATA INTEGRATION IN WIRELESS NETWORKDS

A novel Multiple Access Control(MAC) protocol-User-dependent Perfect-scheduling Multiple Access(UPMA) protocol,which supports joint transmission of voice and data packets,is proposed.By this protocol,the bandwidth can be allocated dynamically to the uplink and downlink traffic with on-demand assignment and the transmission of Mobile Terminals(MTs) can be perfectly scheduled by means of polling.Meanwhile.a unique frame stucture is designed to guarantee Quality of Service(QoS) in voice traffic supporting.An effective colision resolution algorthm is also proposed to guarantee rapid channel access for activated MTs.Finally,performance of UPMA protocol is evaluated by simulation and compared with MPRMA protocol.Simulation results show that UPMA protocol has better performance.     

A new scheduling algorithm to provide proportional QoS in optical burst switching networks

A new scheduling algorithm, which aims to provide proportional and controllable QoS （Quality of Service） in terms of burst loss probability for OBS （Optical Burst Switching） networks, is proposed on the basis of a survey of QoS schemes in current OBS networks. With simulations, performance analysis and comparisons are carried out in detail. The results show that, in the proposed scheme, burst loss probabilities are proportional to the given factors and the control of QoS performance can be achieved with better performance. This scheme will be beneficial to the OBS network management and the tariffpolicy making.     

A new proportional differentiation scheme based on batch scheduling for optical burst switching networks

Optical burst switching (OBS) is a promising switching paradigm for building the next generation optical internet. The proportional differentiation model is very convenient for network operators to quantitatively adjust the quality differentiation among service classes. To provide proportional differentiated services for OBS networks, a proportional differentiation scheme based on batch scheduling is proposed in this article. The scheme adopts the batch scheduling idea to reserve data channel resources for a batch of data bursts. It helps to decrease burst dropping probability. When some data bursts are unsuccessfully scheduled, a preemption method is used to keep a proportional burst dropping probability among service classes according to the expected burst dropping probability equations given by the proportional differentiation model. The scheme has low computational complexity. Simulation results show that the scheme can provide proportional differentiated services and efficiently decrease the burst dropping probability.

多维正交天线的鲁棒波束成形算法分析

将服务质量(QoS)概念引入码分多址(CDMA)系统鲁棒波束成形(BF)的分析,通过对基站端天线阵元空间排列的调整,使接收信号同时在三维空间进行处理,使用凸优化算法对各维信号进行多目标约束优化,最终形成所需的合成发射波束模式。文中最后给出了仿真结果,并与WUSIC及MMSE算法进行了性能比较。     

分布式队列服务算法在无线网状网包调度中的应用

根据无线网状网的包调度特点,结合已有的差分队列服务算法和分布式贝尔曼-福特算 法,将有线网络中的差分队列服务算法改进为分布式队列服务算法（DQS）,使之实用于无 线网状网中多任务条件下实现系统的吞吐量最大化。仿真实验证明了DQS算法能有效地避免 传统多径传输中的按“类”或 “流”来进行调度的缺陷,有效地减少了数据包的端到端 延时和缓冲区需求,尤其是DQS算法的实际平均吞吐量性能有了很大的提高。     

A wireless multimedia transmission control algorithm over heterogeneous IP networks

In this paper,an algorithm Wireless Multimedia Transmission Control(WMTC) is proposed for multimedia transmission control over wired-wireless networks.The relationship between packet length and packet loss rate in the Gilbert wireless error model is investigated.Furthermore,the algorithm can detect the nature of packet losses by sending large and small packets alternately,and control the sending rate of nodes.In addition,by means of updating factor K,this algorithm can adapt to the changes of network states...     

Web service selection algorithm based on principal component analysis

Existing Web service selection approaches usually assume that preferences of users have been provided in a quantitative form by users. However, due to the subjectivity and vagueness of preferences, it may be impractical for users to specify quantitative and exact preferences. Moreover, due to that Quality of Service (QoS) attributes are often interrelated, existing Web service selection approaches which employ weighted summation of QoS attribute values to compute the overall QoS of Web services may produce inaccurate results, since they do not take correlations among QoS attributes into account. To resolve these problems, a Web service selection framework considering user’s preference priority is proposed, which incorporates a searching mechanism with QoS range setting to identify services satisfying the user’s QoS constraints. With the identified service candidates, based on the idea of Principal Component Analysis (PCA), an algorithm of Web service selection named PCA-WSS (Web Service Selection based on PCA) is proposed, which can eliminate the correlations among QoS attributes and compute the overall QoS of Web services accurately. After computing the overall QoS for each service, the algorithm ranks the Web service candidates based on their overall QoS and recommends services with top QoS values to users. Finally, the effectiveness and feasibility of our approach are validated by experiments, i.e. the selected Web service by our approach is given high average evaluation than other ones by users and the time cost of PCA-WSS algorithm is not affected acutely by the number of service candidates.     

移动IPv6中QoS的实现

现有的网络服务质量(QoS)有两大模型:集成服务(Intserv)和区分服务(D iffserv)。这两种服务都是针对静态环境(固定主机和固定路由)设计的,对于移动通信网络都不能完全适用。本文结合集成服务和区分服务的优点,提出了一种新的双平面的三重QoS体系,并描述了这一体系对端到端QoS的实现。最后通过实例概述了QoS体系的整体流程,扩展了移动IPv6(M IPv6)信令中的绑定升级(BU)、绑定请求(BR)、绑定确认(BA)三个选项。     

对数比例公平队列:一种新的调度算法

Internet路由器中的队列调度算法关系到用户数据流能够获得的服务质量以及整个网络的性能,该文提出了一种新的队列调度算法对数比例公平队列调度算法,并通过理论分析和仿真说明了该队列调度算法的一些特性,这种算法不仅实现了网络总效用、网络传输性能与资源分配公平性的折衷,还具有对恶意用户的惩罚作用,鼓励用户使用合理的端到端流量控制算法。     

一种用于流控和资源管理的区分业务Fast-TCP机制

该文提出了一种传统TCP技术的改进方案基于区分业务的 Fast-TCP 机制,简称区分业务F-TCP。通过探讨和借鉴相关的流控、调度及队列管理策略,进一步提出了区分业务F-TCP的实现算法。大量的仿真结果证实了这种机制及其实现算法的可行性和有效性,以及相关的缓冲区占用量突发的估计公式。该机制可在现有的Internet网络中有效地提供业务区分。     

一种按比例补偿的无线公平调度算法

该文提出了一种按比例补偿的无线公平调度算法,算法区分不同的服务类别并可根据其业务需要进行不同的调度。考虑到无线信道的特殊性,算法引入了补偿和再分配模式。其中补偿模式采用了针对滞后流按照其预约速率的固定比例进行补偿的方式。     

IP网络中的QoS技术

如何为IP网络中的业务提供QoS保障正成为IP技术所要解决的一个重点问题,它关系到IP网络的发展前景.总结了近几年来IPQoS的最新发展,并就其中的几个关键问题作一介绍和分析.     

QoS-driven asynchronous uplink subchannel allocation algorithms for space-time OFDM-CDMA systems in wireless networks

In order to support the diverse Quality of Service (QoS) requirements for differentiated data applications in broadband wireless networks, advanced techniques such as space-time coding (STC) and orthogonal frequency division multiplexing (OFDM) are implemented at the physical layer. However, the employment of such techniques evidently affects the subchannel-allocation algorithms at the medium access control (MAC) layer. In this paper, we propose the QoS-driven cross-layer subchannel-allocation algorithms for data transmissions over asynchronous uplink space-time OFDM-CDMA wireless networks. We mainly focus on QoS requirements of maximizing the best-effort throughput and proportional bandwidth fairness, while minimizing the upper-bound of scheduling delay. Our extensive simulations show that the proposed infrastructure and algorithms can achieve high bandwidth fairness and system throughput while reducing scheduling delay over wireless networks. Xi Zhang (S’89-SM’98) received the B.S. and M.S. degrees from Xidian University, Xi’an, China, the M.S. degree from Lehigh University, Bethlehem, PA, all in electrical engineering and computer science, and the Ph.D. degree in electrical engineering and computer science (Electrical Engineering—Systems) from The University of Michigan, Ann Arbor, USA. He is currently an Assistant Professor and the Founding Director of the Networking and Information Systems Laboratory, Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas, USA. He was an Assistant Professor and the Founding Director of the Division of Computer Systems Engineering, Department of Electrical Engineering and Computer Science, Beijing Information Technology Engineering Institute, Beijing, China, from 1984 to 1989. He was a Research Fellow with the School of Electrical Engineering, University of Technology, Sydney, Australia, and the Department of Electrical and Computer Engineering, James Cook University, Queensland, Australia, under a Fellowship from the Chinese National Commission of Education. He worked as a Summer Intern with the Networks and Distributed Systems Research Department, Bell Laboratories, Murray Hills, NJ, and with AT&T Laboratories Research, Florham Park, NJ, in 1997. He has published more than 80 technical papers. His current research interests focus on the areas of wireless networks and communications, mobile computing, cross-layer designs and optimizations for QoS guarantees over mobile wireless networks, wireless sensor and Ad Hoc networks, wireless and wireline network security, network protocols design and modeling for QoS guarantees over multicast (and unicast) wireless (and wireline) networks, statistical communications theory, random signal processing, and distributed computer-control systems. Dr. Zhang received the U.S. National Science Foundation CAREER Award in 2004 for his research in the areas of mobile wireless and multicast networking and systems. He is currently serving as an Editor for the IEEE Transactions on Wireless Communications, an Associated Editor for the IEEE Transactions on Vehicular Technology, and and Associated Editor for the IEEE Communications Letters, and is also currently serving as a Guest Editor for the IEEE Wireless Communications Magazine for the Special Issues of “Next Generation of CDMA vs. OFDMA for 4G Wireless Applications”. He has served or is serving as the Panelist on the U.S. National Science Foundation Research-Proposal Review Panel in 2004, the WiFi-Hotspots/WLAN and QoS Panelist at the IEEE QShine 2004, as the Symposium Chair for the IEEE International Cross-Layer Designs and Protocols Symposium within the IEEE International Wireless Communications and Mobile Computing Conference (IWCMC) 2006, the Technical Program Committee Co-Chair for the IEEE IWCMC 2006, the Poster Chair for the IEEE QShine 2006, the Publicity Co-Chair for the IEEE WirelessCom 2005, and as the Technical Program Committee members for IEEE GLOBECOM, IEEE ICC, IEEE WCNC, IEEE VTC, IEEE QShine, IEEE WoWMoM, IEEE WirelessCom, and IEEE EIT. He is a Senior Member of the IEEE and a member of the Association for Computing Machinery (ACM). Jia Tang (S’03) received the B.S. degree in electrical engineering from Xi’an Jiaotong University, Xi’an, China, in 2001. He is currently a Research Assistant working towards the Ph.D. degree in the Networking and Information Systems Laboratory, Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas, USA. His research interests include mobile wireless communications and networks, with emphasis on cross-layer design and optimizations, wireless quality-of-service (QoS) provisioning for mobile multimedia networks, wireless diversity techniques, and wireless resource allocation. Mr. Tang received the Fouraker Graduate Research Fellowship Award from the Department of Electrical and Computer Engineering, Texas A&M University in 2005.     

抗毁WDM网中支持QoS的选路和波长分配算法

该文首先探讨了抗毁WDM网中支持QoS的分层图模型,在此基础上提出一种抗毁WDM网中支持QoS的选路和波长分配算法。该算法根据上层业务不同的QoS要求,对其光路建立请求区别对待,以满足它们不同的阻塞率和恢复率要求。计算机仿真结果表明该算法既满足了上层业务不同的QoS要求,同时又充分利用了有限的网络资源,使全网的平均阻塞率降低。     

New architecture of IP QoS management system

Based on the analysis of current Quality of Service （QoS） management on IP network, new generation of QoS architecture QoSAF is proposed. QoSAF is divided into three layers： resource control layer, network service layer and business layer. QoS management is accomplished by interactivity of layers. In this architecture, mechanism of feedback control enhances the functions of resource management and system monitoring. The principle of design and logical architecture of system is discussed in detail.