Designing collaborative,constructionist and contextual applications for handheld devices

This paper explores current applications for handheld devices and questions which of these make full use of the unique attributes of handheld devices in order to facilitate learning in a pedagogically sensible manner. In order to do so, the paper presents a functional framework which analyses handheld application in relation to their use as well as the pedagogical underpinning, if any, that informs their development. Our framework currently consists of seven distinct categories of application, which we term: administrative, referential, interactive, microworld, data collection, location aware and collaborative. We argue that three categories, namely data collection, location aware and collaborative, are particularly suited to learning with handheld devices when they are informed by collaborative, contextual and constructionist learning theories. Furthermore, we contend that applications of the type just outlined deserve further research since they are not attempting to replicate, or even augment, existing learning scenarios but rather they try to create new learning opportunities which would not be possible without (mobile) technology. Finally, the authors introduce a number of applications and learning scenarios that they have developed for handheld devices and explain their position within the framework.     

Do handheld devices facilitate face‐to‐face collaboration? Handheld devices with large shared display groupware to facilitate group interactions

Abstract   One-to-one computing environments change and improve classroom dynamics as individual students can bring handheld devices fitted with wireless communication capabilities into the classrooms. However, the screens of handheld devices, being designed for individual-user mobile application, limit promotion of interaction among groups of learners. This study proposes a design of classrooms that incorporates personal workspace and public workspace. Students use handheld devices as private workspace and work with peers on public workspace with shared displays through their handheld devices. Experiments confirmed that students with only handheld devices did not demonstrate expected participation ratios and actively interact with group members. The proposed shared display groupware promoted shared understanding of the workspace and increased awareness of partner actions. Collaboration was enhanced by creating the opportunity for students to use handheld devices to perform ideal communication patterns and avoiding ineffective communication patterns.     

Proximate sharing of geo data using the credit-considered mobile edge computing server switching control scheme

This paper proposed a mobile edge computing (MEC)-based point of interests (POIs) downloading and proximate sharing system for a group of people, who belong to the same mobile social networks in proximity (MSN-P) and whose handheld devices are connected in a tree-like structure. Using the proposed system, the root handheld device plays the role of an MEC server and is charge of downloading POIs' contents from the remote cloud server using 4G/5G cellular network and then forwarding POIs' contents to other group members' handheld devices using device-to-device (D2D) communication. Since the number of connected handheld devices in each handheld device is limited using D2D communication, this work proposed a control scheme called k-Connection-Limited and n-Hop (kCL-nH) tree topology's construction scheme to achieve the proximate sharing of POIs' contents. Additionally, since the root handheld device consumes more battery power than others, this work proposed a control scheme that has each group member's handheld device to be the root handheld device alternatively. A credit scheme was thus proposed to denote each handheld device's contribution, which is referred for the selecting of the next root handheld device, to achieve the fairness concern. Then, the control scheme, which is executed in the corresponding MEC server, considering both remaining battery power and credit for the switching of the root handheld device was designed. The proposed method was developed using Wi-Fi Direct over the iOS system. Experimental results have shown some interested results among power consumption, downloaded data volume and fairness among all handheld devices.     

Ubi-App: a ubiquitous application for universal access from handheld devices

Universal access from a handheld device (such as a PDA, cell phone) at any time or anywhere is now a reality. Ubicomp Assistant (UA) (Sharmin et al. in Proceedings of the 21st annual ACM symposium on applied computing (ACM SAC 2006), Dijon, France, pp 1013–1017, 2006) is an integral service of MARKS (Sharmin et al. in Proceedings of the third international conference on information technology: new generations (ITNG 2006), Las Vegas, Nevada, USA, pp 306–313, 2006). It is a middleware developed for handheld devices, and has been designed to accommodate different types of users (e.g., education, healthcare, marketing, or business). This customizable service employs the ubiquitous nature of current short range, low-power wireless connectivity and readily available, low-cost lightweight mobile devices. These devices can reach other neighbouring devices using a free short-range ad hoc network. To the best of the authors’ knowledge, the UA service is the only service designed for these devices. This paper presents the details of Ubi-App, a ubiquitous application for universal access from any handheld device, which uses UA as a service. The results of a usability test and performance evaluation of the prototype show that Ubi-App is useful, easy to use, easy to install, and does not degrade the performance of the device.     

A resource aware software partitioning algorithm based on mobility constraints in pervasive grid environments

Pervasive computing suffers from resource limitations of mobile devices, while grid computing can utilize almost unlimited resources distributed in the whole Internet. The conjunction of such two paradigms generates a new promising one, called pervasive grid computing, where mobile users can use handheld devices to access abundant resources and services in the grid. In this paper, a novel software partitioning algorithm is presented, which is suitable for pervasive grid to optimally allocate software components between a mobile device and one or more servers, with the goal of saving the resources of mobile devices. The algorithm takes into account component mobility constraints to not only prevent violating execution requirements of the application, but also to fully exploit component mobility, replication and rebinding to conserve more resources as compared to previous works. Another distinguishing feature of the algorithm is its generality, which can be applied to minimize network bandwidth usage, response time and energy consumption, respectively or simultaneously. Extensive simulation results have demonstrated the validity and effectiveness of the proposed algorithm in various environments.     

An energy-efficient video transport protocol for personal cloud-based computing

Recently, we are surrounded by a collection of heterogeneous computing devices such as desktop computers, laptops, smart phones, smart televisions, and tablet PCs. Each device is operated with its own host operating system, has its own internal architecture, and performs its independent tasks with its own applications and data. A common property amongst these devices, namely that of internet-connectivity, allows them to configure personal virtual cloud system by interconnecting each other through an intermediate switching device. The personal cloud service should provide a seamlessly unified computing environment across multiple devices with synchronized data and application programs. As such, it allows users to freely switch their workspace from one device to another while continuing the interaction with the available applications. In order to support video applications, the cloud system should provide seamless video synchronization among the multiple devices. However, we note that the current cloud services do not provide efficient data flow among devices. In this paper, we propose and develop a new reliable transport protocol to support video synchronization for the personal virtual cloud system. In order to cope with battery limitation of many mobile devices in personal virtual cloud system, the proposed protocol is designed to provide energy efficient video communications. Our simulation results show that the proposed protocol can reduce end users power consumption up to 25 % compared to the legacy TCP with given packet loss probabilities and the average length of error bursts.     

基于普适计算的虚拟场景自适应网络发布研究

针对移动设备访问三维虚拟场景受到网络带宽和终端计算能力的制约,使得在线利用虚拟现实进行移动学习效率不高,基于此提出了基于普适计算的自适应优化选择技术.对三维实体进行本体语义描述,建立相应的优化模型.在此基础上通过WURFL对手持移动设备进行采样获取设备参数,对参数进行分析从而建立普适规则,利用普适计算进行自适应优化选择.测试结果表明,经过自适应选择后手持移动设备荻取三维虚拟场景资源的速度和效率得到明显提高.     

Peer-assisted adaptation in periodic broadcasting of videos for heterogeneous clients

The increasing use of streaming applications and wide variety of devices, such as handheld personal organizers, have raised new challenges, such as the provision of access to multimedia content for devices with limited computing and bandwidth capabilities. In this paper, we propose a technique for periodic broadcasting. Our technique allows clients with low bandwidth capability to be served in the same period as high-bandwidth clients, using peer-to-peer streaming between clients, and also works for clients with downstream capability below the video bit rate. In the proposed system, the server builds multicast trees of clients that allow clients with low bandwidth to be served by other clients with sufficient upstream bandwidth. Clients below the video bit rate will suffer additional, but only moderately noticeable, delays that occur as video is converted to lower quality. We performed extensive simulation and showed that our system can provide improved service performance for heterogeneous clients on periodic broadcasting protocols.     

Device ensembles [ubiquitous computing]

The ubiquity of wireless local and personal area networks, an expanding array of intelligent handheld devices, and an increasingly mobile lifestyle are enabling new forms of ensemble computing. Looking across four system layers - link, network, data, and application - the authors survey the technologies, standards, and leading-edge research making device ensembles a reality.     

Scenes: Abstracting interaction in immersive sensor networks

Pervasive computing deployments are increasingly using sensor networks to build instrumented environments that provide local data to immersed mobile applications. These applications demand opportunistic and unpredictable interactions with local devices. While this direct communication has the potential to reduce both overhead and latency, it deviates significantly from existing uses of sensor networks that funnel information to a static central collection point. This pervasive computing driven perspective demands new communication abstractions that enable the required direct communication among mobile applications and sensors. This paper presents the scene abstraction, which allows immersed applications to create dynamic distributed data structures over the immersive sensor network. A scene is created based on application requirements, properties of the underlying network, and properties of the physical environment. This paper details our work on defining scenes, providing an abstract model, an implementation, and an evaluation.     

Vision-based single-stroke character recognition for wearable computing

Particularly when compared to traditional tools such as a keyboard or mouse, wearable computing data entry tools offer increased mobility and flexibility. Such tools include touch screens, hand gesture and facial expression recognition, speech recognition, and key systems. We describe a new approach for recognizing characters drawn by hand gestures or by a pointer on a user's forearm captured by a digital camera. We draw each character as a single, isolated stroke using a Graffiti-like alphabet. Our algorithm enables effective and quick character recognition. The resulting character recognition system has potential for application in mobile communication and computing devices such as phones, laptop computers, handheld computers and personal data assistants.     

A collaborative face-to-face design support system based on sketching and gesturing

Mobile and pervasive computing has seen a rapid development in the last years. Portable, handheld computing devices are getting more popular as their capabilities increase. Therefore, people having the need to work on-the-field have now the possibility to be supported by computer technology, for example, garden or building designers. Ad-hoc networking capabilities of handheld devices enable the development of supporting tools for collaborative work anywhere. This paper presents MCSketcher, a system that enables face-to-face collaborative design based on sketches using handheld devices equipped for spontaneous wireless peer-to-peer networking. It is especially targeted for supporting preliminary, in-the-field work, allowing designers to exchange ideas through sketches on empty sheets or over a recently taken photograph of the object being worked on, in a brainstorming-like working style. Pen-based designed human–computer interaction is the key to supporting collaborative work. The gestures-based command input results in a lightweight yet efficient and easy to use interface. Graph structured hierarchical documents help to overcome the problems of a small screen size.     

移动环境下的低开销自动数据收集算法

移动计算的一个重要难题是断连操作.数据收集过程是指在断连前把用户将来可能访问的数据预先存储到本地缓存的过程.收集过程的结果将明显影响断连操作的性能.提出了一种低开销的通用数据收集算法,在访问数据时同步建立数据之间的关联,并在数据关联的基础上自动选择要收集的数据集.模拟试验结果表明,该算法可以有效地提高断连操作时的cache 命中率,尤其适用于计算速度慢、存储容量小的手持移动设备.     

移动应用中基于物理隔离的数据同步方法

随着嵌入式技术、现代通讯技术的发展以及新一代通讯标准的出现,使得人们使用大规模智能移动设备进行移动计算成为可能。本文针对移动应用提出了一种在物理隔离网络环境下的数据同步方法,介绍了应用的背景,对同步系统进行总体设计,详细说明了数据同步操作的步骤及过程,然后详细论述了同步过程中冲突的检测、处理规则。采用增量式的同步方法,减少了数据交互量;同时,内外网物理隔离,保证了数据的安全性。     

手持移动计算中的多通道交互

手持移动计算已逐渐成为当今主流的计算模式之一,人机交互是其中的关键问题.多通道用户界面和多通道交互方式能够有效地提高移动环境中人机交互的效率.讨论了移动环境中的多通道交互模型,并结合设计开发的移动导游系统TGH(tour guide on hand),分析了多通道交互在手持移动计算中的应用.性能测试表明,笔和语音结合的多通道交互方式在移动环境中能够较好地提高人机交互效率.     

REST风格服务在跨平台数据传输中的研究与应用

利用手持设备进行移动办公已经成为一种趋势,由于手持设备难以进行大型的数据库存储和软件应用,且手持设备与服务端的平台与技术也不尽相同,因此相互之间如何进行高效的数据交互就成为亟待解决的问题,针对这一问题,该文在研究WCF与REST风格的基础上,对Android平台客户端与.NET服务端之间的数据交互进行了设计与实现。     

Rendezvousing with location-aware devices: Enhancing social coordination

Emerging technologies such as location-awareness devices have the potential to significantly impact users' social coordination, particularly while rendezvousing. It is important that we explore how new technologies influence social behaviours and communication in order to realize their full potential. This paper presents a field study investigating the use of mobile location-aware devices for rendezvous activities. Participants took part in one of three mobile device conditions (a mobile phone, a location-aware handheld, or both a mobile phone and a location-aware handheld) and completed three rendezvousing scenarios. The results reveal key differences in communication patterns between the mediums, as well as the potential strengths and limitations of location-aware devices for social coordination. The paper concludes with a discussion of relevant design issues drawn from observations gathered during the field study.     

Ubiquitous enterprise service adaptations based on contextual user behavior

Recent advances in mobile technologies and infrastructures have created the demand for ubiquitous access to enterprise services from mobile handheld devices. Further, with the invention of new interaction devices, the context in which the services are being used becomes an integral part of the activity carried out with the system. Traditional human–computer interface (HCI) theories are now inadequate for developing these context-aware applications, as we believe that the notion of context should be extended to different categories: computing contexts, user contexts, and physical contexts for ubiquitous computing. This demands a new paradigm for system requirements elicitation and design in order to make good use of such extended context information captured from mobile user behavior. Instead of redesigning or adapting existing enterprise services in an ad hoc manner, we introduce a methodology for the elicitation of context-aware adaptation requirements and the matching of context-awareness features to the target context by capability matching. For the implementation of such adaptations, we propose the use of three tiers of views: user interface views, data views, and process views. This approach centers on a novel notion of process views to ubiquitous service adaptation, where mobile users may execute a more concise version or modified procedure of the original process according to their behavior under different contexts. The process view also serves as the key mechanism for integrating user interface views and data views. Based on this model, we analyze the design and implementation issues of some common ubiquitous access situations and show how to adapt them systematically into a context-aware application by considering the requirements of a ubiquitous enterprise information system.

Lightweight security for mobile commerce transactions

This paper describes a lightweight security mechanism for protecting electronic transactions conducted over the mobile platform. In a typical mobile computing environment, one or more of the transacting parties are based on some wireless handheld devices. Electronic transactions conducted over the mobile platform are gaining popularity and it is widely accepted that mobile computing is a natural extension of the wired Internet computing world. However, security over the mobile platform is more critical due to the open nature of wireless networks. Furthermore, security is more difficult to implement on the mobile platform because of the resource limitation of mobile handheld devices. Therefore, security mechanisms for protecting traditional computer communications need to be revisited so as to ensure that electronic transactions involving mobile devices can be secured and implemented in an effective manner. This research is part of our effort in designing security infrastructure for electronic commerce systems, which extend from the wired to the wireless Internet. A lightweight mechanism was designed to meet the security needs in face of the resource constraints. The proposed mechanism is proven to be practical in real deployment environment.     

Towards Mobile Cloud Computing with Single Sign-on Access

The low computing power of mobile devices impedes the development of mobile applications with a heavy computing load. Mobile Cloud Computing (MCC) has emerged as the solution to this by connecting mobile devices with the “infinite” computing power of the Cloud. As mobile devices typically communicate over untrusted networks, it becomes necessary to secure the communications to avoid privacy-sensitive data breaches. This paper presents work on implementing MCC applications with secure communications. For that purpose, we built on COMPSs-Mobile, a redesigned implementation of the COMP Superscalar (COMPSs) framework aiming to MCC platorms. COMPSs-Mobile automatically exploits the parallelism inherent in an application and orchestrates its execution on loosely-coupled distributed environment. To avoid a vendor lock-in, this extension leverages on the Generic Security Services Application Program Interface (GSSAPI) (RFC2743) as a generic way to access security services to provide communications with authentication, secrecy and integrity. Besides, GSSAPI allows applications to take profit of more advanced features, such as Federated Identity or Single Sign-On, which the underlying security framework could provide. To validate the practicality of the proposal, we use Kerberos as the security services provider to implement SSO; however, applications do not authenticate themselves and require users to obtain and place the credentials beforehand. To evaluate the performance, we conducted some tests running an application on a smartphone offloading tasks to a private cloud. Our results show that the overhead of securing the communications is acceptable.