普适计算环境下的设备请求代理模型*

为了给普适计算环境提供一个统一的应用架构和模式,本文从普适计算研究现状出发,通过借鉴对象请求代理技术,提出了设备请求代理模型,建立了设备基件的远程映射管理和统一调度机制,有效降低了普适计算环境下应用程序的开发难度和兼容传统应用程序。     

普适计算环境下基于移动Agent的分布式交互方法

为提高普适计算环境下人机交互的透明性和持久性,提出一种基于移动Agent的分布式交互方法,用户通过由移动Agent实现的交互Agent在网络中进行交流。交互Agent代表用户作为交互的对等实体,根据需要在网络中迁移并保持交互状态,通过可定制的各种行为和协同运作方式实现不同的交互应用。该方法能够实现交互实体之间透明的、智能的、可移动的交互过程,提供及时的交互服务和灵活的信息共享方式。     

Metropolitan area video-on-demand service using pyramid broadcasting

Pyramid broadcasting is a new way of giving video-on-demand service on a metropolitan scale. We multiplex the most frequently requested movies on the network, gaining a radical improvement in access time and bandwidth use. This is achieved by using storage at the receiving end. As the available bandwidth increases, the improvement in access time is exponential instead of linear as in conventional broadcasting. The larger the bandwidth of the network is, the better gain in the access time due to pyramid broadcasting. As the access-time requirement decreases, the bandwidth in conventional broadcasting increases linearly, while the bandwidth in pyramid broadcasting increases only logarithmically. We provide analytical and experimental evaluations of pyramid broadcasting based on its implementation on an Ethernet LAN.     

普适环境下农业智能生产系统设计构思

本文分析了不同时代下的农业生产模式,构思设计了普适计算环境下的农业生产系统的系统模型和框架结构图.展望了普适农业环境下可能的农业生产场景,分析了普适环境下农业系统实现的必要条件和面临的挑战.本文内容是普适思想与农业领域的一次结合,对未来普适环境下自动化农业生产系统的发展有一定的参考意义.     

移动普适环境中支持QoS控制的安全框架研究

基于对移动普适计算环境所面临的安全威胁的分析,从用户,网络和服务提供商3个方面总结了移动普适计算环境的特殊安全需求,并提出一种适用于移动普适计算环境且支持QoS(quality of service)控制的安全框架.对该框架的相关功能操作和工作时序进行了介绍,并着重研究和实现了安全框架中的QoS控制流程.通过此框架,移动互联网设备用户可以随时随地访问移动普适计算环境并获得高质量的安全服务.     

面向普适计算的用户隐私量化方法研究

无论通信系统如何发展,隐私对于用户来说都是最重要的,用户的隐私是否想透露该由用户亲自决断。然而,由于信息互联业务的发展,用户经常被询问隐私信息的请求所打扰。而普适计算是强调用户和环境融为一体的计算,其出发点是想让用户尽量少地参与系统的计算、传输等过程。如果普适计算想要更广泛地得到推广,对隐私发放实现自动控制是根本目标。提出了以用户为中心、以系统为中心、混合量化等多种方法,并在对各种方法进行实验比对,明确其使用环境以及优缺点,在免除打扰用户和隐私保护等方面能达到比较好的平衡性能,可以为将来普适计算中关于隐私的自动防护提供参考。     

An effective authentication mechanism for ubiquitous collaboration in heterogeneous computing environment

With the advent of new generation of mobile access devices such as smartphone and tablet PC, there is coming a need for ubiquitous collaboration which allows people to access information systems with their disparate access devices and to communicate with others in anytime and in anywhere. As the number of collaborators with a large number of disparate access devices increases in ubiquitous collaboration environment, the difficulties for protecting secured resources from unauthorized users as well as unsecured access devices will increase since the resources can be compromised by inadequately secured human and devices. Therfore, authentication mechanism for access of legitimate participants is essential in ubiquitous collaboration environment. In this paper we present an efficient authentication mechanism in ubiquitous collaboration environment. We show that proposed scheme is secure through security analysis and is efficient through the experimental results obtained from the practical evaluation of the scheme in ubiquitous collaboration environment.     

Mobile cloud computing framework for a pervasive and ubiquitous environment

The increasing use of wireless Internet and smartphone has accelerated the need for pervasive and ubiquitous computing (PUC). Smartphones stimulate growth of location-based service and mobile cloud computing. However, smartphone mobile computing poses challenges because of the limited battery capacity, constraints of wireless networks and the limitations of device. A fundamental challenge arises as a result of power-inefficiency of location awareness. The location awareness is one of smartphone’s killer applications; it runs steadily and consumes a large amount of power. Another fundamental challenge stems from the fact that smartphone mobile devices are generally less powerful than other devices. Therefore, it is necessary to offload the computation-intensive part by careful partitioning of application functions across a cloud. In this paper, we propose an energy-efficient location-based service (LBS) and mobile cloud convergence. This framework reduces the power dissipation of LBSs by substituting power-intensive sensors with the use of less-power-intensive sensors, when the smartphone is in a static state, for example, when lying idle on a table in an office. The substitution is controlled by a finite state machine with a user-movement detection strategy. We also propose a seamless connection handover mechanism between different access networks. For convenient on-site establishment, our approach is based on the end-to-end architecture between server and a smartphone that is independent of the internal architecture of current 3G cellular networks.     

普适计算环境下基于情境的提醒服务自协调策略研究

由于老年人生理机能减退,针对老年人的提醒服务应用十分广泛.该类服务应考虑到老人的活动特征和环境特征才能提高服务效果,减少不必要的干扰.情境感知技术的发展为提醒服务的改进提供了契机,将情境引入到提醒服务的设计中,采用OWL本体方法构建领域内情境与服务知识的语义模型,以提醒服务平台的方式集成领域内提醒相关的设备与服务,并结合本体模型采用SWRL规则设计提醒服务的自协调策略,从而提高平台上不同提醒服务的自适应能力.通过模拟若干情境,采用Protégé和Pellet推理机验证了本体模型的正确性和协调规则的有效性.     

An interleaving crescent broadcasting protocol for near video-on-demand services

This work presents a novel interleaving crescent broadcasting protocol for near video-on-demand service. The interleaving crescent broadcasting protocol is a trade-off among the subscriber’s access latency, maximum buffer requirement, needed subscriber’s bandwidth, and maximum disk I/O transfer rate. A longer subscriber’s access latency may cause a subscriber to leave. A lower maximum buffer requirement, a lower needed subscriber’s bandwidth, and a lower maximum disk I/O transfer rate reduce subscribers’ costs. The interleaving crescent broadcasting protocol not only makes access latency shorter, but also lowers the overall system’s cost. We prove the correctness of the interleaving crescent protocol; provide mathematical analyses to demonstrate its efficiency.     

Dynamic broadcasting in parallel computing

We consider the problem where broadcast requests are dynamically generated at random time instants at each node of a multiprocessor network. In particular, in our model packets arrive at each node of a network according to a Poisson process, and each packet has to be broadcast to all the other nodes. We propose an on-line, distributed routing scheme to execute the broadcasts in this dynamic environment. Our scheme consists of repeated execution of a partial multinode broadcast task, which is a static communication task where any M⩽N arbitrary nodes of an N-processor network broadcast a packet to all the other nodes. The dynamic broadcasting scheme that we propose can be used in any topology, regular or not, for which partial multinode broadcast algorithms with certain properties can be found. We derive such an algorithm and we analyze the corresponding dynamic broadcasting scheme for the hypercube network. We show that its stability region tends to the maximum possible as the number of nodes of the hypercube tends to infinity. Furthermore, for any fixed load in the stability region, the average delay is of the order of the diameter of the hypercube. Our analysis does not use any approximating assumptions     

Extension of practical channel transition broadcasting for near video-on-demand applications

Periodic broadcasting is a cost-effective solution for the large-scale distribution of popular videos. This strategy guarantees constant worst service latency to all clients, regardless of the number of video requests. The practical channel transition broadcasting (PCTB) scheme is an essential periodic broadcasting method that can dynamically add or release broadcasting channels (i.e., channel transition) according to video popularity. However, PCTB experiences bandwidth waste when performing channel transition. This study further finds that PCTB yields transition playback latency during channel addition. Therefore, an enhanced version referred to as PCTB+ is proposed to cause less bandwidth waste and lower transition playback latency. The applicability of this new scheme is verified, and an analytical evaluation is provided to demonstrate its performance advantage. The new scheme reduces bandwidth waste by 50 % to 100 % compared to the original PCTB scheme. Moreover, PCTB+ yields 50 % smaller transition playback latency than PCTB. The proposed scheme outperforms the seamless fast broadcasting (SFB) scheme for bandwidth waste under most conditions. No extra startup latency and client buffer demand are required when using PCTB+.     

Discovery systems in ubiquitous computing

Ubiquitous computing introduces unique requirements for discovery technologies, which let services and devices become aware of each other without explicit human administration. Discovery lets services and devices spontaneously become aware of the availability and capability of peers on the network without explicit administration. In practice, this means that a client can discover and potentially use a device without prior knowledge of it. Although discovery is a necessary component of ubiquitous computing, the wide range of discovery systems in use today reflects the varied needs of the communities from which they originated. Some of these features are appropriate for ubiquitous computing, but others require further research and development.     

Wearable and ubiquitous computing

Describes a course on wearable and ubiquitous computing. It has been taught twice at Virginia Tech. The article describes the course's scope, assignments and grading, and design projects.     

A practical use of learning system using user preference in ubiquitous computing environment

U-learning, or ubiquitous learning, has become the state-of-the-art educational trend in information technology. In ubiquitous learning environment, students now have the ability to learn anytime and anywhere. In many computer-assisted learning systems (such as e-learning, m-learning and u-learning), students must follow the lesson plans and learning environments established by the teacher. To overcome this limitation and increase effective learning, new techniques that reflect alternative learning styles, such as self-directed learning, adaptive learning and personalized learning, have been developed. These techniques have been researched extensively, but they still do not consistently reflect the specific needs of all students. In this article, a u-learning system is proposed that considers the learning level and preferences of each learner. The system provides information about the student’s preferred learning section and difficulty level of learning contents and indicates the areas that may require additional study (based on the educational history of the student), thus allowing students to set up an optimized learning environment. A topic preference vector was applied to calculate the student’s preferences, and the learning section and the difficulty level were used as each vector value in the system. To verify the effectiveness of the proposed system, an English-learning system was implemented using content from the reading comprehension section of the Test of English for International Communication (TOEIC). An experiment was conducted using a control group and a test group. The results demonstrated that the system proposed in this paper is useful for improving learning efficiency.     

Context-awareness in wearable and ubiquitous computing

A common focus shared by researchers in mobile, ubiquitous and wearable computing is the attempt to break away from the traditional desktop computing paradigm. Computational services need to become as mobile as their users. Whether that service mobility is achieved by equipping the user with computational power or by instrumenting the environment, all services need to be extended to take advantage of the constantly changing context in which they are accessed. This paper will report on work carried out by the Future Computing Environments Group at Georgia Tech to provide infrastructure for context-aware computing. We will describe some of the fundamental issues involved in contextaware computing, solutions we have generated to provide a flexible infrastructure and several applications that take advantage of context awareness to allow freedom from traditional desktop computing.     

Location-based services in ubiquitous computing environments

This paper presents a framework for providing dynamically deployable services in ubiquitous computing settings. The goal of the framework is to provide people, places, and objects with computational functionalities to support and annotate them. Using RFID-based tracking systems, the framework detects the locations of physical entities, such as people or things, and deploys services bound to the entities at proper computing devices near where they are located. It enables location-based and personalized information services to be implemented as mobile agents and operated at stationary or mobile computing devices, which are at appropriate locations, even if the services do not have any location-information. This paper presents the rationale, design, implementation, and applications of our prototype infrastructure.     

基于CC/PP的普适计算中私有信息保护问题的研究

对在普适计算环境中如何更有效地保护用户私有信息的问题进行了研究和探讨。提出了对用户私有信息进行分级／分类处理的思想方法,有效地提高了处理的效率和效果。通过对W3C的CC／PP(Composite Capabilities／Preferences Profiles)标准进行扩展,完成了eCC／PP(extended Composite Capabilities／Preferences Profiles)框架的建立工作,初步实现了这种分级／分类保护信息的思想方法。     

Convenience and TAM in a ubiquitous computing environment: The case of wireless LAN

Ubiquitous computing technology is seen as an emerging new information technology with such potency that it has changed the way we view IT. Although perceived ease of use and perceived usefulness constructs have been considered important in determining the individuals’ acceptance and use of IT in the last few decades, factors contributing to the acceptance of a new IT are likely to vary according to the technological characteristics, the target users, and the context.In this study, we will introduce convenience as a new factor that reflects the characteristic of ubiquitous computing technology. In addition, we chose wireless LAN as an initial stage technology of ubiquitous computing to empirically validate the extended technology acceptance model (TAM) applied in a ubiquitous computing environment.