基于始终最佳体验的终端聚合的研究与实现*

统一业务终端通过分布式的终端设备协同提供应用体验,是B3G系统终端架构的一个发展方向。统一业务终端形成的终端业务环境提供始终最佳体验的服务模式,并主要体现在其对分布式终端组件的动态聚合重构上。在动态重构聚合的实现中,首先对体验质量进行量化建模,将各分布式终端的能力映射到能力服务器（CS）,推导出满意度的评估函数及其约束条件,ABE服务模型。其次,基于此服务模型详细设计出终端聚合控制机制,并且提出解决UST频繁切换所引起的性能瓶颈的快速判决算法。     

泛在网下基于上下文感知的虚拟终端技术研究

泛在网络环境下,业务提供必须根据网络和终端条件、用户偏好的变化而自适应地变化。因此,文中阐述了虚拟终端中的上下文感知功能,其为泛在多样性业务的开发提供了不可或缺的信息来源。提出一种应用于虚拟终端系统的上下文感知中间件体系结构,该中间件可以将各类应用场景中终端环境的特征参数进行抽象,形成可获知、可描述的上下文。提出应用该上下文感知技术的业务应用模型。最后通过一个多媒体业务接续场景对上述定义、抽象方法和业务模型进行验证。结果表明,该方法可以有效地为泛在多样性业务提取所需的上下文信息;通过该模型,业务平台和多构终端环境可以进行动态适配,为用户提供多样性和最佳体验的服务。     

一种服务网格动态信息聚合模型及其应用

在动态、跨组织的网格环境中如何进行适应组织重构、业务变化等动态性要求的信息聚合是现实应用中亟待解决的问题．文章提出了服务网格动态信息聚合模型。从组织模型、数据模型、协作模型三个维度描述信息聚合中变化的因素．基于此模型．给出了一种支持动态信息聚合的实现框架,它能够适应网格组织结构变化、业务变化,协调人的参与,进而提高系统动态性．最后介绍了该模型及其实现框架在远程学习评价网格LAGrid中的应用情况．     

下一代网络中统一业务终端的研究

基于VoIP技术的下一代网络（NGN)是一个融合了语音、视频、数据和即时消息等多种业务种类的网络。然而，目前NGN中的硬终端却缺乏同时承载上述业务的能力。因此，迫切需要在NGN硬终端上提供一种统一业务的开放平台，由其来容纳各种业务应用并提供业务支撑软件和业务应用程序的升级更新。文章重点阐述了下一代网络中统一业务终端的模型、终端统一业务开放平台的结构及网络侧对统一业务终端的支持等相关技术。     

基于AOP与Elastos操作系统的平等计算模型实现

由于构件对象可以动态加载、动态聚合,同时也能动态卸载、动态拆离,使得软件可以运行在计算能力或存储能力较弱的设备上.通过基于AOP及E1astos操作系统的平等计算模型的实现,在很大程度上提高了应用的终端适应能力,从而为开发更大的移动应用提供了技术支持.     

基于端和云的大规模上下文管理框架的研究与实现

上下文态势是将大规模、广地域范围内的上下文信息综合在一起形成的一种全局信息.随着各类具备感知能力的移动终端的普及,如何获取这种全局态势并利用态势来为用户提供更好的服务是亟待解决的问题.基于“端+云”相结合的计算模式,提出移动终端的统一抽象模型来实现上下文信息收集,进而提出了在云端对大规模上下文信息进行聚合、基于MapReduce计算模型的态势信息荻取算法.通过一个大规模上下文管理框架对研究内容进行验证,并以一个交通态势实例验证了框架的有效性.     

基于面向服务架构的分布式业务部署平台

针对分布式环境下业务系统运营中资源利用率低、可靠性差和扩展性弱等问题,设计了一种基于面向服务架构的分布式业务部署平台。该平台基于面向服务架构(SOA)组件模型,可自动化地部署和管理分布式业务系统;根据服务组件运行状态,动态为其分配计算资源,实现业务能力的动态扩展和收缩;同时,采用双机热备、高可用集群机、业务迁移等机制保证了高可靠性。仿真实验表明,该平台能在保证业务服务质量(QoS)的同时具有较高资源利用率。     

基于业务抽象规划的分布式动态服务组合算法

异构系统间难以实现计算资源的灵活共享,制约分布式信息系统性能的提升,基于面向服务架构的Web服务技术,为异构系统计算资源共享提供了有效手段。为此,针对Web服务组合在集中式发布架构下单点故障和性能瓶颈问题,提出一种基于业务抽象规划的分布式动态服务组合算法。该算法根据组合规划结果对业务抽象规划库进行动态扩充,快速组合出满足需求的服务,逐步提高服务组合响应率。仿真结果表明,该算法在分布式环境下可减少服务请求过程中交互的信息量,降低请求响应时间,提高服务组合效率。     

Web服务的控制集成

在软件集成的研究中,控制集成是一个重要的组成部分,研究了Web服务的控制集成,提出了Web服务的包容模型与聚合模型,包容模型使用容器对Web服务进行封装,对外提供统一的服务访问接口,Web服务消费者通过该接口访问Web服务;聚合模型使用聚合器对Web服务进行管理,聚合器本身不参与Web服务调用,它向Web服务消费者提供Web服务的链接,Web服务消费者在从聚合器处获得链接后再访问相应的服务,其成果已经在一个原型系统中得到了验证.     

基于AOP与Elastos操作系统的平等计算模型实现*

由于构件对象可以动态加载、动态聚合,同时也能动态卸载、动态拆离,使得软件可以运行在计算能力或存储能力较弱的设备上。通过基于AOP及Elastos操作系统的平等计算模型的实现,在很大程度上提高了应用的终端适应能力,从而为开发更大的移动应用提供了技术支持。     

面向移动云存储的属性基解密服务中间件

属性基加密（ABE）算法支持对云端数据的细粒度访问控制。针对属性基解密计算复杂度高,难以在资源受限的移动终端上实现的问题,提出并实现了一种面向移动云存储的属性基解密服务中间件。在保证密文信息不被中间件获取的前提下,中间件为移动终端代理属性基解密服务,实现了基于树形结构的线性秘密共享（LSSS）矩阵求解,降低了终端的计算与通信开销,提高了解密速度;属性权威可以在不需要用户参与的条件下,即时、细粒度地撤销用户属性;所有接口均使用Restful服务,保证了通用性。实验结果表明,属性基解密服务中间件提高移动设备解密性能近30倍,具备较好的并发性能,属性撤销具有实用性。     

一种基于0MADM的设备管理系统

针对移动终端增值业务设计的盲目性问题提出设备能力系统层次模型,建立厂商设备能力和用户设备能力概念,定义涵盖采集、验证、管理、描述等方面的管理流程。利用多种相关协议设计基于开放移动联盟设备管理规范的终端能力管理系统框架,原型系统整合了终端能力管理系统和流媒体服务,实验结果表明,该框架能较好地满足服务质量个性化要求。     

An approach to decentralized control of large scale systems using aggregation methods

A two-level decentralized control structure is formulated for large scale interconnected subsystems controlled byNdecision makers. Chained aggregation is used to decompose the overall team problem with a decentralized information structure into (N + 1) subproblems: one low order team problem with a centralized information structure andNdecentralized optimal control problems. Accordingly, the control of each decision maker is decomposed into three components: a decoupling control which induces aggregation, a local control which controls the subsystem dynamics, and an aggregate control which controls the dynamics of the interconnection variables. The robustness of this composite control with respect to perturbations in the system dynamics and the cost functional is established.     

Generic user revocation systems for attribute-based encryption in cloud storage

Cloud-based storage is a service model for businesses and individual users that involves paid or free storage resources. This service model enables on-demand storage capacity and management to users anywhere via the Internet. Because most cloud storage is provided by third-party service providers, the trust required for the cloud storage providers and the shared multi-tenant environment present special challenges for data protection and access control. Attribute-based encryption (ABE) not only protects data secrecy, but also has ciphertexts or decryption keys associated with fine-grained access policies that are automatically enforced during the decryption process. This enforcement puts data access under control at each data item level. However, ABE schemes have practical limitations on dynamic user revocation. In this paper, we propose two generic user revocation systems for ABE with user privacy protection, user revocation via ciphertext re-encryption (UR-CRE) and user revocation via cloud storage providers (UR-CSP), which work with any type of ABE scheme to dynamically revoke users.     

Stochastic inclusion principle applied to decentralized automatic generation control

An input-state-output inclusion principle for linear stochastic systems is proposed, with the emphasis on restriction and aggregation conditions for estimators and dynamic controllers. Inclusion of the LQG (linear quadratic Gaussian) optimal design is formulated and applied to the decentralized overlapping control of large-scale interconnected systems. Applications of the proposed methodology are illustrated using a stochastic model of automatic generation control (AGC) for interconnected power systems. Three types of overlapping decentralized and fully decentralized dynamic controllers, consisting of state estimators and feedback gains, are proposed for the cases of full and reduced measurement sets. An extensive analysis of both steady-state and transient regimes under a variety of operating conditions shows the superiority of the proposed AGC scheme with respect to the standard AGC designs.     

Trustworthy service composition with secure data transmission in sensor networks

As the basis of the Internet of Things (IoT), sensor networks have materialized its computation and communication capability into anything in our modern lives. Service composition provides us a promising way to cooperate various sensors to build more powerful IoT applications over sensor networks. However, the limited capability of sensor node poses great challenges not only to trustworthy service composition but also to secure data aggregation. The complex composite structure, computation-intensive evaluation, and massive data transmission become burdens for service composition in sensor networks. To overcome these issues, this paper proposes a distributed approach to enable efficient trustworthy service composition with secure data transmission in sensor networks. By analyzing dependency relationships, the rules for computing service trust and data trust are proposed based a multi-level trust model. Then, each target component service can be evaluated independently through a model checker. Moreover, an identity-based aggregate signature is introduced in the composite evaluation to guarantee the secure data transmission among different components. The experimental results show that our approach not only achieves efficient trustworthy service composition with complex invocation structures, but also reduces the costs in the secure data transmission.     

Advanced multicast class-based bandwidth over-provisioning

Dynamic bandwidth aggregate over-provisioning has been proposed to provide differentiated services with scalable Quality of Service (QoS) control. Previous research showed that efficient over-reservation control allows minimizing QoS control overhead with reduced waste of bandwidth and blocking probability. However, existing over-reservation centric solutions are still inefficient in the face of network dynamics, as they are not able to accommodate the dynamic service demands, thus failing to optimize the bandwidth usage. This paper proposes a new Advanced Class-based resource Over-Reservation (ACOR) solution for multicast sessions, which seeks increased network resources utilization while minimizing QoS control overhead. More specifically, ACOR is able to dynamically update the share of bandwidth between different classes of service, providing improved results with less complexity than current solutions. Our analytical and simulation results prove the cost-effective and scalable QoS control capabilities of ACOR in decentralized networks with multiple distributed ingress routers coordinating the QoS control.     

一种基于执行力模型的服务平台自主控制方法

开放的分布式服务平台倾向于涵盖更丰富的管理功能,支持更强的分散交互性,从而导致软件管理和维护的难度和成本问题日益突出.为此,引入一种自管理的服务平台体系结构参考模型,以构件作为功能实现载体,服务作为功能组织手段,交互作为功能扩展方式.提出了一种基于分层反馈的自主控制架构,以服务构件及相互之间的交互关系为控制对象,执行力模型为决策基础.在管理服务的可用性和性能建模中运用了马尔可夫过程、随机Petri网和排队网模型理论,并考虑了链路和节点的失效修复机制.仿真结果表明,基于排队Petri网的执行力模型能够反映失效率和修复时间对服务平台性能和可用性的影响,并验证了自主控制方法对提高服务平台有效性的积极作用.     

SRA-MSDU: Enhanced A-MSDU frame aggregation with selective retransmission in 802.11n wireless networks

The main goal of the IEEE 802.11n standard is to achieve more than 100 Mbps of throughput at the MAC service access point. This high throughput has been achieved via many enhancements in both the physical and MAC layers. One of the MAC enhancements is the frame aggregation in which multiple frames are concatenated into a single large frame before being transmitted. The 802.11n MAC layer defines two types of aggregation, aggregate MAC service data unit (A-MSDU) and aggregate MAC protocol data unit (A-MPDU). The A-MPDU outperforms A-MSDU due to its large aggregation size and the subframes retransmission in erroneous channels. However, in error free channels and under the same aggregation size the A-MSDU performs better than the A-MPDU due to its smaller headers. Thus, adding a selective retransmission capability to the A-MSDU would improve the system performance. In this paper, we have proposed an MSDU frame aggregation scheme that enables selective retransmission at the MSDU level without altering the original MAC header. In this proposed scheme an implicit sequence control mechanism has been introduced in order to keep the frames in sequence and preserve their correct order at the receiver side. The results show that the proposed scheme improves the system performance in terms of throughput and delay even under highly erroneous channels.     

基于CAR构件的面向方面编程聚合模型的研究

通过识别、封装和集成不同种类的关注点来构件系统，从而提高系统的适应性、可维护性和重用性。面向方面编程（AOP）技术是目前较好的分离关注点的编程范式。基于CAR构件系统，提出了AOP的动态聚合模型及其实现。与其他系统的静态聚合方法相比，动态聚合所具有的随时聚合、随时拆卸的特点更加有效的提高了系统的适应性和重用性。