Piecewise Network Awareness Service for Wireless/Mobile Pervasive Computing

This paper presents a piecewise framework for network awareness service (NAS) for wireless/mobile pervasive computing. We investigate how piecewise consideration of wired and wireless elements of the framework architecture benefits service advertisement and discovery and network-awareness techniques. We also discuss scalability of the NAS framework with respect to platform computing capabilities. The framework is suitable for a wide range of computing devices, from powerful ones with multi-tasking operating systems (OS) to small ones with lightweight OS. Case studies applying the NAS framework to sensor monitoring in home networks and data streaming in pervasive multimedia computing are presented. The analytical results on the performance of the NAS framework in these case studies show that it has significant advantages over traditional network-awareness frameworks in terms of reducing wireless bandwidth consumption and saving battery energy of mobile devices.     

基于移动多智能体的分布式系统软件架构研究

在对比分析当前可用的分布式计算的计算模式的基础上,主要研究基于移动多智能体的分布式系统的软件体系结构。提出了一个基於移动智能Agent的分布式系统构架,给出了一种扩展请求器-中介器-供应器的嵌套式客户/Agent/服务器计算模式。在此基础上,讨论了一个基于Java的智能Agent构建的宏观经济决策支持系统框架和工作机制。经验分析表明,上述基於多智能体的分布式系统架构是可行的,并表现出更大的灵活性、自主性。     

Centaurus: An Infrastructure for Service Management in Ubiquitous Computing Environments

In the near future, we will see dramatic changes in computing and networking hardware. A large number of devices (e.g., phones, PDAs, even small household appliances) will become computationally enabled. Micro/nano sensors will be widely embedded in most engineered artifacts, from the clothes we wear to the roads we drive on. All of these devices will be (wirelessly) networked using Bluetooth, IEEE 802.15 or IEEE 802.11 for short range connectivity creating pervasive environments. In this age where a large number of wirelessly networked appliances and devices are becoming commonplace, there is a necessity for providing a standard interface to them that is easily accessible by any user. This paper outlines the design of Centaurus, an infrastructure for presenting services to heterogeneous mobile clients in a physical space via some short range wireless links. The infrastructure is communication medium independent; we have implemented the system over Bluetooth, CDPD and Infrared, three well-known wireless technologies. All the components in our model use a language based on Extensible Markup Language (XML) for communication, giving the system a uniform and easily adaptable interface. Centaurus defines a uniform infrastructure for heterogeneous services, both hardware and software, to be made available to diverse mobile users within a confined space.     

移动互联网终端技术

文章基于移动互联网终端类型、主流智能操作系统、人机交互界面及热点应用等方面的技术进展,分析了当前主要的移动互联网终端技术。文章认为由于移动互联网终端在系统硬件技术、人机交互技术、操作系统技术、商业模式和应用开发上的跳跃性发展,将带动移动互联网终端以及移动互联网应用服务市场的高速扩张;云计算概念的出现、应用服务概念的推广将进一步推动移动互联网的快速发展,移动互联网终端市场亦将呈现繁荣景象。     

Clustering hypervisors to minimize failures in mobile cloud computing

Resource virtualization has become one of the key super‐power mobile computing architecture technologies. As mobile devices and multimedia traffic have increased dramatically, the load on mobile cloud computing systems has become heavier. Under such conditions, mobile cloud system reliability becomes a challenging task. In this paper, we propose a new model using a naive Bayes classifier for hypervisor failure prediction and prevention in mobile cloud computing. We exploit real‐time monitoring data in combination with historical maintenance data, which achieves higher accuracy in failure prediction and early failure‐risk detection. After detecting hypervisors at risk, we perform live migration of virtual servers within a cluster, which decreases the load and prevents failures in the cloud. We performed a simulation for verification. According to the experimental results, our proposed model shows good accuracy in failure prediction and the possibility of decreasing downtime in a hypervisor service. Copyright © 2017 John Wiley & Sons, Ltd.     

A Service Management Framework for M-Commerce Applications

Mobile commerce (m-commerce) refers to an ability to conduct wireless commerce transactions using mobile applications in mobile devices. M-commerce applications can range from as simple as an address book synchronization to as complicated as credit card transactions. M-commerce is expected to grow dramatically in the near future supporting simple to complex commerce transactions. Even though the Wireless Application Protocol (WAP) is designed to facilitate the development of wireless applications, it will not be sufficient to handle complex business transactions that require cooperation of different service applications. In order to handle these complex mobile commerce transactions efficiently, an intelligent, robust and scalable framework that provides diverse m-commerce services is required. This paper describes in detail such an m-commerce framework based on the Java Intelligent Network Infrastructure (JINI) and Wireless Applications Protocol (WAP).     

Adaptive wireless thin‐client model for mobile computing

The thin‐client computing model has the potential to significantly increase the performance of mobile computing environments. By delivering any application through a single, small‐footprint client (called a thin client) implemented on a mobile device, it is possible to optimize application performance without the need for building wireless application gateways. We thus present two significant contributions in the area of wireless thin‐client computing. Firstly, a mathematical performance model is derived for wireless thin‐client system. This model identifies factors that affect the performance of the system and supports derivation and analysis of adaptation strategies to maintain a user‐specified quality of service (QoS). Secondly, a proxy‐based adaptation framework is developed for wireless thin‐client systems, which dynamically optimizes performance of a wireless thin client via dynamically discovered context. This is implemented with rule‐based fuzzy logic that responds to variations in wireless link bandwidth and client processing power. Our fuzzy inference engine uses contextual data to dynamically optimize tradeoffs among different quality of service parameters offered to the end users. Additionally, our adaptation framework uses highly scalable wavelet‐based image coding to provide scalable QoS that can degrade gracefully. Our thin‐client adaptation framework shields the user from ill effects of highly variable wireless network quality and mobile device resources. This improves performance of active applications, in which the display changes frequently. Further, active application behaviour may produce high transmission latency for screen updates, which can adversely affect user perception of QoS, resulting in poor interactivity. We report measured adaptive performance under realistic mobile device and network conditions for several different clients and servers. Copyright © 2008 John Wiley & Sons, Ltd.     

Supporting the WWW in Wireless Communications Through Mobile Agents

Mobile computing is considered of major importance to the computing industry for the forthcoming years due to the progress in wireless mobile communications. We present a proxy-based architecture that manages to accelerate Web browsing in wireless Customer Premises Networks (CPN). We discuss how such an architecture is implemented using the IBM Aglets framework for mobile agents. The suggested architecture relies heavily on proxy caches – maintained in base stations – which are relocated to follow a roaming user in other control areas (clusters of cells). The cache management scheme involves relocation of full caches to the most-likely-to-be visited control areas, but also fractions of the cache to less-likely-to-be-visited neighbours. A movement prediction algorithm, based on a learning automaton, is used to determine the future location of the terminal. The discussed architecture components have been implemented as Aglets to allow for the efficient introduction of the service in a CPN infrastructure.     

Organization of Invalidation Reports for Energy-Efficient Cache Invalidation in Mobile Environments

In a wireless environment, mobile clients often cache frequently accessed data to reduce contention on the limited wireless bandwidth. However, it is difficult for clients to ascertain the validity of their cache content because of their frequent disconnection. One promising cache invalidation approach is the Bit-Sequences scheme that organizes invalidation reports as a set of binary bit sequences with an associated set of timestamps. The report is periodically broadcast by the server to clients listening to the communication channel. While the approach has been shown to be effective, it is not energy efficient as clients are expected to examine the entire invalidation report. In this paper, we reexamine the Bit-Sequences method and study different organizations of the invalidation report to facilitate clients to selectively tune to the portion of the report that are of interest to them. This allows the clients to minimize the power consumption when invalidating their cache content. We conducted extensive studies based on a simulation model. Our study shows that, compared to the Bit-Sequences approach, the proposed schemes are not only equally effective in salvaging the cache content but are more efficient in energy utilization.     

On-Demand Data Broadcasting for Mobile Decision Making

The wide spread of mobile computing devices is transforming the newly emerged e-business world into a mobile e-business one, a world in which hand-held computers are the user's front-ends to access enterprise data. For good mobile decision making, users need to count on up-to-date, business-critical data. Such data are typically in the form of summarized information tailored to suit the user's analysis interests. In this paper, we are addressing the issue of time and energy efficient delivery of summary tables to mobile users with hand-held computers equipped with OLAP (On-Line Analytical Processing) front-end tools. Towards this, we propose a new on-demand scheduling algorithm, called STOBS, that exploits the derivation semantics among OLAP summary tables. It maximizes the aggregated data sharing between mobile users and reduces the broadcast length for satisfying a set of requests compared to the already existing techniques. The algorithm effectiveness with respect to access time and energy consumption is evaluated using simulation.     

基于代理的移动事务处理模型

在移动计算环境中，为了支持断连操作，一方面，需要在移动客户端上进行数据缓存；另一方面，在重新连接后，移动客户端上的暂时事务需要在服务器上重新执行，这使得事务的一致性很难得到保障。扩展嵌套事务的概念并提出了一种模型，通过在事务执行机制中加入移动代理，使事务执行时数据的一致性在频繁断连状态下能满足应用要求。     

边缘计算中的网络建设需求分析

文章系统介绍了移动边缘计算关键技术,详细分析了MEC网络平台架构及功能,对于典型与应用场景中的数据分流业务进行了论述和介绍。在5G网络应用中,MEC技术通过为移动网边缘,无线接入网提供IT服务,同时提供强大的云计算能力,满足了本地化业务、近距离部署的功能要求,极大地提高了用户体验。     

基于Web Service和移动Agent的电子商务议价系统的研究

电子商务帮助人们突破了时间和空间的限制，扩大了交易的对象与范围．但往往一笔交易必须查询及比较多个网站，分别和许多交易对象进行议价，这种复杂性阻碍了电子商务的快速发展。为了使电子商务企业提供人性化、个性化的服务，实现资源集成共享，节约商务成本．作者提出了一个基于Web Service和移动Agent的电子商务议价系统框架。     

Intelligent file transfer for smart handheld devices based on mobile cloud computing

Most methods of file transfer between mobile devices have to take considerable time to obtain and input target identifiers. To speed up file sharing of mobile devices, an intelligent file transfer framework is designed based on mobile cloud computing. Only single‐finger action is performed in the proposed framework, which just drags the file to the target face on the touchscreen of a mobile device. The dragged file can be transmitted to the target receiver who can either get the file immediately as her/his mobile device is online or receive the file later after connecting to the Internet. Our framework provides the following features: (i) users do not need to know the target identifier in advance; (ii) users do not need to input identity information by themselves; and (iii) users can select a specific target among multiple candidates from the camera of a mobile device. The intelligent file transfer framework reveals an efficient architecture and innovative user interfaces to transfer files between mobile devices, which can significantly reduce the complexity and difficulty of file sharing. An Android‐based prototype is implemented to verify the feasibility and superiority of our framework. Experimental results show that our approach outperforms existing schemes and can save large amounts of time in file sharing for mobile users. Copyright © 2015 John Wiley & Sons, Ltd.     

XMIDDLE: A Data-Sharing Middleware for Mobile Computing

An increasing number of distributed applications will be written for mobilehosts, such as laptop computers, third generation mobile phones, personaldigital assistants, watches and the like. Application engineers have to dealwith a new set of problems caused by mobility, such as low bandwidth, contextchanges or loss of connectivity. During disconnection, users will typicallyupdate local replicas of shared data independently from each other. Theresulting inconsistent replicas need to be reconciled upon re-connection. Tosupport building mobile applications that use both replication andreconciliation over ad-hoc networks, we have designed xmiddle, a mobilecomputing middleware. In this paper we describe xmiddle and show how it usesreflection capabilities to allow application engineers to influencereplication and reconciliation techniques. xmiddle enables the transparentsharing of XML documents across heterogeneous mobile hosts, allowing on-lineand off-line access to data. We describe xmiddle using a collaborativee-shopping case study on mobile clients.     

Adaptive delivery of video data over wireless and mobile environments

We present an architecture for the adaptable delivery of video data under variable connection characteristics and into devices of variable capabilities. The main application of the proposed architecture is video delivery in wireless and mobile environments. The architecture is based on the Universal Multimedia Access concept and the MPEG‐7 standard. Based on the network and the mobile device, as well as constraints imposed by user preferences and the multimedia content, video is delivered through a careful application of a combination of off‐line and on‐line reductions to the video stream. We present our architecture and describe an implementation of a system based on the architecture. We present basic performance evaluation results to quantify the merit of our approach. Copyright © 2002 John Wiley & Sons, Ltd.     

Mobile user recovery in the context of Internet transactions

With the expansion of Web sites to include business functions, a user interfaces with e-businesses through an interactive and multistep process, which is often time-consuming. For mobile users accessing the Web over digital cellular networks, the failure of the wireless link, a frequent occurrence, can result in the loss of work accomplished prior to the disruption. This work must then be repeated upon subsequent reconnection - often at significant cost in time and computation. This "disconnection-reconnection-repeat work" cycle may cause mobile clients to incur substantial monetary as well as resource (such as battery power) costs. In this paper, we propose a protocol for "recovering" a user to an appropriate recent interaction state after such a failure. The objective is to minimize the amount of work that needs to be redone upon restart after failure. Whereas classical database recovery focuses on recovering the system, i.e., all transactions, our work considers the problem of recovering a particular user interaction with the system. This recovery problem encompasses several interesting subproblems: (1) modeling user interaction in a way that is useful for recovery, (2) characterizing a user's "recovery state", (3) determining the state to which a user should be recovered, and (4) defining a recovery mechanism. We describe the user interaction with one or more Web sites using intuitive and familiar concepts from database transactions. We call this interaction an Internet transaction (iTX), distinguish this notion from extant transaction models, and develop a model for it, as well as for a user's state on a Web site. Based on the twin foundations of our iTX and state models, we finally describe an effective protocol for recovering users to valid states in Internet interactions.     

一种基于GPRS网络的缓存一致性策略

提出了在GPRS网络中加入一个验证服务器VS维护无线移动环境下的缓存一致性的策略,利用GPRS骨干网中SGSN的有关移动终端的位置信息和用户访问的局域性,有针对性地只向在线终端发送所缓存数据的失效信息,有效地降低异步传输中的信息量。性能分析表明,该策略简化了维护缓存一致性的复杂性,使用很少的移动终端计算量,支持任意断开连接时间和一个PLMN网内的漫游。     

A Low-Complexity Routing Algorithm with Power Control for Self-Organizing Short-Range Wireless Networks

Mobile computing has become very pervasive, where the number of electronic devices equipped with wireless capabilities has increased significantly in recent years. This poses serious demands on wireless, mobile and self-organizing networks. Despite the fact that devices are getting smaller and more powerful, advances in battery technology have not yet reached the stage where devices can autonomously operate for days. Therefore, devices for self-organizing networks will strongly rely on the efficient use of their batteries. We present a cluster-based low-complexity routing algorithm for self-organizing networks of mobile nodes. Our proposed algorithm, called Cluster-based Energy-saving Routing Algorithm (CERA), allows mobile nodes to autonomously create clusters to minimize the power consumption. CERA is implemented as two separate protocols: the intra-cluster data-dissemination protocol, and the inter-cluster routing protocol. We present an extensive analysis of the overall protocol architecture by varying the critical factors related to protocol behavior. As a result, the CERA implementation generally saves up to 25% of energy, while keeping the overhead, in terms of energy consumption, acceptably low.     

On-Site Volume Rendering with GPU-Enabled Devices

Now that high-performance computing systems can rely more on a cloud based infrastructure, it becomes much more important to have ubiquitous data processing and visualization capability. This will allow data sharing among numerous clients using shared data repositories through a secure web server. Thanks to the wide availability of GPU support in today’s mobile devices such as smart phones and tablets, as well as the recently published WebGL standard, pervasive computing for high-quality and real-time volume rendering may be realized on such high-performance platforms. We have invented two high-performance volume renderers, namely, single-pass GPU ray caster and fast 3D texture slicer, for both mobile and desktop platforms. Rigorous experiments and performance assessments reveal that the proposed mobile 3D image rendering system outperforms the existing approaches in the literature.