基于SDN的卫星网络端到端QoS类映射研究

针对在多个卫星网络域环境下域间协作困难,以及如何在各个卫星网络域内选择合适的QoS类实现端到端QoS类映射的问题,基于软件定义卫星网络架构,首先,提出一种SDN卫星网络域间通信方案,以及面向多QoS类的端到端服务交付数据包处理方法。其次,提出一种基于多准则决策的控制模块。模块利用ELECTRE方法,在ELECTRE方法中通过综合权重法计算出各个卫星网络域内QoS指标相应的权重系数,并且利用ELECTRE方法对每个QoS类的净支配指数进行排序,从而为端到端路径的每个卫星网络域选择合适的QoS类。最后,与现有端到端QoS类映射方案进行比较,仿真结果表明,上述方法在多卫星网络域环境下保证端到端的时延、时延抖动、丢包率和代价。

Web services composition with QoS bound based on simulated annealing algorithm

In order to enable quality-aware web services selection in the process of service composition,this paper first describes the non-functional requirements of service consumers and the quality of elementary service or composite service as a quality vector,and then models the QoS（quality of service）-aware composition as a multiple criteria optimization problem in extending directed graph.A novel simulated annealing algorithm for QoS-aware web services composition is presented.A normalizing for composite service QoS values is made,and a secondary iterative optimization is used in the algorithm.Experimental results show that the simulated annealing algorithm can satisfy the multiple criteria and global QoS requirements of service consumers.The algorithm produces near optimum solution with much less computation cost.

云服务推荐中基于多源特征和多任务学习的时序QoS预测

随着云计算技术的普及,云服务数量指数级增长,用户不再满足于功能性需求,服务质量(Quality of Service,QoS)成为比较服务优劣的关键性能指标.如何在动态、复杂的云环境中实时、准确地预测服务质量并为用户推荐高质量服务成为热点问题.考虑到云服务器的负载、网络状态、用户接入云环境的偏好等随着时间变化,本文提出了基于多源特征和多任务学习的时序QoS预测方法(T-MST),它可以实时、准确地同时预测多种QoS属性.首先,TMST对用户、服务进行特征表示,通过Time2Vec刻画时序特征,再结合多种QoS属性的历史记录生成多源特征表示.其次,基于滑动窗口采用LSTM感知窗口内的时序关系,借助注意力机制细化窗口内不同时刻的关键性,从而构造待预测时刻的隐藏状态.最后,T-MST采用多任务预测层实现多种QoS属性的同时预测,它们共享上游模型,仅在预测层采用不同的感知模块以提升模型的鲁棒性和计算效率.本文基于真实世界的数据集进行了全面的实验验证,结果表明T-MST在吞吐量和响应时间的时序预测任务上平均绝对误差(Mean Absolute Error,MAE)分别平均提升了37.53%和20.38%,优于现有的时序QoS预测方法;而且TMST的计算效率更高,能够有效应对实时QoS预测的需求.

基于代理的Web Services QoS模型研究

服务质量(QoS)描述了服务满足消费者需求的能力,提供有保证的QoS是Web服务在商业应用中获得成功的关键。本文分析了Web Services QoS的特点和实现过程,提出一种更适合于Web Services环境下的QoS建模过程,提出一种基于代理的有QoS保障的Web Services模型。通过在传统的Web Services架构的基础上进行扩展,增加一个代理,充分发挥代理技术的灵活性、可扩充性、可重用性等优点。将QoS的相关工作完全交给代理来完成,实现一个改进的Web Services QoS架构。

QoS驱动的Web services动态计价机制研究

结合Web services的服务质量(QoS)因素和用户经验,对Web services的计价机制进行研究,提出一种QoS驱动的Web services动态计价模型,描述其计价过程,并给出相应的实现算法。通过对模型的简单实现,经测试这一计价模型在准确性和合理性上具有一定优势。

5G-R调度通信QoS协商和业务流程设计

随着铁路发展,移动通信业务需求不断增加,同时,移动通信技术迭代创新,铁路亟待发展新一代宽带移动通信系统(5G-R)。调度通信业务是5G-R承载的重要业务,为规范业务流程,明确设备要求,保证设备互联互通,需研究调度通信QoS协商和业务流程。首先,研究5G-R调度通信业务需求和系统架构;其次,研究QoS控制管理方式,提出基于N5接口动态协商QoS机制,研究N5接口服务架构和服务操作;然后,重点研究语音、视频个呼、组呼等典型业务流程,研究功能寻址和位置寻址业务实现方案,提出N5接口技术要求;最后,依托研发实验室进行测试验证。试验表明,业务流程和实现方案技术上可行性,实现了功能扩展,性能明显提升,个呼建立时间从不大于10 s减少为2.65 s,且基于N5接口动态协商QoS机制能够保障业务优先级,实现不同厂家设备互联互通。建议结合试验线进一步优化业务流程。

悬停波动对毫米波无人机通信系统QoS的影响研究

毫米波无人机通信是未来通信中一种很有前途的候选者。然而,悬停无人机的随机波动会影响该通信系统的服务质量,并给毫米波无人机通信的应用带来挑战。该文从无人机位置波动对无人机-用户链路质量的影响的角度出发,研究无人机位置波动对空对地毫米波无人机通信系统QoS的影响。以可靠服务概率及覆盖概率作为评估系统QoS的指标,基于随机几何获得QoS评估指标的表达式并通过蒙特卡洛仿真进行验证。结果显示,QoS随无人机波动强度的增加而降低且存在使QoS最大的最优无人机高度,为毫米波无人机通信网的设计与研究提供参考依据。

数字电视信号在IP网络传输中的QoS保障技术应用

数字电视信号对传输质量有着十分严苛的要求,传统网际互连协议(Internet Protocol,IP)网络在提供端到端服务质量(Quality of Service,QoS)保障方面仍面临诸多挑战。对此,分析数字电视信号的业务特点和传输需求,梳理IP网络QoS领域的发展脉络,提出一种端到端QoS保障解决方案的总体架构,从接入网、骨干网、综合管理平台三个层面给出优化措施。

IP承载网中QOS策略的设计与优化

在网络世界中,网际互连协议(Internet Protocol,IP)承载网扮演着信息流动的骨干角色,其运行表现和服务水准至关重要。文章详细探讨了IP承载网中服务质量(Quality of Service,QoS)策略的设计与优化方法,重点涵盖分类服务与标记、流量控制与优先级队列管理以及链路和节点策略的具体实现。通过流量分析与预测、智能资源分配与调度、动态策略调整以及故障检测与容错机制,提出一系列提升网络性能和用户体验的有效措施。

基于QoS的Web Services发现

出于对组合Web服务中QoS管理的目的,对WSDL进行扩展提出了新的服务描述语言,并扩展了Web服务的角色,提出了服务代理角色,在传统的Web Services架构的基础上进行扩展给出了一个改进的Web Services架构,最后给出了原型系统的实现方案和试验;并对试验结果作了分析,得出了改进后的Web service架构在服务发现时性能、效率优于传统的web services架构。

A QoS-aware Method for Web Services Discovery

The non-functional QoS (quality of service) information helps us to select a proper Web-service from the web applications, by using component services such as UDDI[1](Universal Description, Discovery, and Integration) and MDS(Monitoring and Discovery System). MDS is a suite of web services to monitor and discover resources and service on Grids, but MDS only based on function aspects. This paper studies on an approach to provide the QoS information and a discovery model by using MDS and gives a system deployment and implementation plan. The simulation results show that the method is effective in service discovery.

Web Services QoS的研究与应用

出于对组合Web服务QoS管理的目的,从对组合服务管理的QoS要求出发,对WSDL进行扩展提出了新的服务描述语言,并扩展了Web服务的角色——服务代理角色,通过在传统的WebServices架构的基础上进行扩展,给出了一个改进的WebServices架构以及原型系统的实现方案和试验,并对试验结果作了分析。

Toward Cloud Computing QoS Architecture:Analysis of Cloud Systems and Cloud Services

Cloud can be defined as a new computing paradigm that provides scalable, on-demand, and virtualized resources for users. In this style of computing, users can access a shared pool of computing resources which are provisioned with minimal management efforts of users. Yet there are some obstacles and concerns about the use of clouds. Guaranteeing quality of service QoS by service providers can be regarded as one of the main concerns for companies tending to use it. Service provisioning in clouds is based on service level agreements representing a contract negotiated between users and providers. According to this contract, if a provider cannot satisfy its agreed application requirements, it should pay penalties as compensation. In this paper, we intend to carry out a comprehensive survey on the models proposed in literature with respect to the implementation principles to address the QoS guarantee issue. © 2014 Chinese Association of Automation.

Semantic QoS Ontology and Semantic Service Ranking Approach for IoT services

Due to a rapid increase in the number of functionally equivalent web services at open and dynamic Io T service environment,Qo S has become a major discrimination factor to reflect the user's expectation and experience of using a service.There are different languages and models for expressing Qo S advertisements and requirements among service providers and consumers.Therefore,it leads to the issues of semantic interoperability of Qo S information and semantic similarity match between a semantic description of the service being requested by the service consumer,and a formal description of the service being offered by the service provider.In this paper,we propose a hierarchical two-layer semantic Qo S ontology to promote the description and declaration of Qo S-based service information in detail for any domain and application.And,we develop a semantic matchmaking algorithm to compare the web services according to their Qo S information and adopt analytical hierarchy process( AHP) to make decision for the ranked services depending on the Qo S criteria.The comparison study and experimental result show that our proposed system is superior to other service ranking approaches.

QOS-Guaranteed Communication Services in CSCW Support Environment

In order to support CSCW (Computer Supported Cooperative Work) applications, some basic technologies must be introduced into the computer supported environment. They are shared workspace, work management and interaction among participants. Computer communication is essential and important for these technologies. In this paper, we will discuss different kinds of communication services required by CSCW. There are three communication styles in CSCW support environment: real time stream transfer, real time block transfer and non real time transfer. These communication services require different QoS quality of service parameters. The architecture of QoS is then analyzed and a framework of a QoS guaranteed communication service platform is proposed.

User-preferences based service selection model in large-scale services with various QoS properties

With the rapid growth of service scale, there are many services with the same functional properties but different non-flmctional properties on the Internet. There have been some global optimizing service selection algorithms for service selection. However, most of those approaches cannot fully reflect users＇ preferences or are not fully suitable for large-scale services selection. In this paper, an ant colony optimization （ACO） algorithm for the model of global optimizing service selection with various quality of srevice （QoS） properties is employed, and a user-preference based large-scale service selection algorithm is proposed. This algorithm aims at optimizing user-preferred QoS properties and selecting services that meet all user-defined QoS thresholds. Experiment results prove that this algorithm is very efficient in this regard.

Hybrid Metaheuristics Web Service Composition Model for QoS Aware Services

Recent advancements in cloud computing(CC)technologies signified that several distinct web services are presently developed and exist at the cloud data centre.Currently,web service composition gains maximum attention among researchers due to its significance in real-time applications.Quality of Service(QoS)aware service composition concerned regarding the election of candidate services with the maximization of the whole QoS.But these models have failed to handle the uncertainties of QoS.The resulting QoS of composite service identified by the clients become unstable and subject to risks of failing composition by end-users.On the other hand,trip planning is an essential technique in supporting digital map services.It aims to determine a set of location based services(LBS)which cover all client intended activities quantified in the query.But the available web service composition solutions do not consider the complicated spatio-temporal features.For resolving this issue,this study develops a new hybridization of the firefly optimization algorithm with fuzzy logic based web service composition model(F3L-WSCM)in a cloud environment for location awareness.The presented F3L-WSCM model involves a discovery module which enables the client to provide a query related to trip planning such as flight booking,hotels,car rentals,etc.At the next stage,the firefly algorithm is applied to generate composition plans to minimize the number of composition plans.Followed by,the fuzzy subtractive clustering(FSC)will select the best composition plan from the available composite plans.Besides,the presented F3L-WSCM model involves four input QoS parameters namely service cost,service availability,service response time,and user rating.An extensive experimental analysis takes place on CloudSim tool and exhibit the superior performance of the presented F3L-WSCM model in terms of accuracy,execution time,and efficiency.

基于时间序列分析的Web Service QoS预测方法

通过网络提供服务的Web Service的服务质量会随着网络环境、服务器负载等因素的变化而变化,如何更好地帮助用户选择在未来一段时间内符合服务质量需求的Web Service,是目前服务计算领域中需要解决的关键问题之一。针对上述问题,提出了一种基于时间序列分析的Web Service QoS预测方法,并实现了相应的Web Service QoS自动预测工具。该工具能够根据Web Service的历史QoS数据,有效地预测未来短期内的QoS信息。以17832个Web Service的历史数据为基础,设计了相关实验,并验证了方法的有效性。

一种可扩展的Web Service QoS管理框架

Web Service是目前研究界和产业界广泛关注的技术之一.随着Web Service的广泛应用,研究者们普遍认识到,服务的非功能属性,即服务质量(Quality of Service,QoS)是面向服务的应用能否成功的关键因素之一.因此,研究者们尝试从多个角度对QoS相关问题展开了研究.然而,现有工作普遍关注基于QoS的动态服务选择和组装等上层应用技术,而对于如何获取、存储、度量QoS等基础支持技术研究较少,而这些基础性工作对QoS相关的研究工作具有显著的重要性.此外,不同应用领域对Web Service QoS的需求不尽相同,因此,需要有一套灵活的机制支持在QoS模型定义、QoS度量方法、QoS信息采集等方面体现出的领域特性.针对这个问题,文中提出了一个可扩展的Web Service QoS信息管理框架,详细分析了该框架涉及到的重要方法与核心技术,并给出了该框架在北京大学软件构件库系统中的设计决策和方案.最后,介绍了文中框架在一个863计划项目中的应用实例,该实例展示了用户根据其应用的领域需求对本框架进行扩展并进行Web Service QoS管理的方法,从而验证了本管理框架的可扩展性及实用性.

一种基于Web Service的分级QoS的研究与实现

随着WebService技术的广泛应用,QoS成为一个非常重要的问题.以服务响应时间为QoS参数,验证了一种基于WebService的分级QoS方法,提出了目标时间预设模型,并针对优化问题提出一种基于动态规划的解决方法,并实现了原型系统.实验数据表明这种方法有效地控制了负载平衡,实现了服务分级.