Recent progress in wireless and sensor technologies has lead to a new development of learning environments, called context-aware ubiquitous learning environment, which is able to sense the situation of learners and provide adaptive supports. Many researchers have been investigating the development of such new learning environments; nevertheless, the criteria of establishing a context-aware ubiquitous learning environment have not yet been clearly defined, not to mention the strategies of conducting effective learning activities. To resolve these problems, this paper presents the basic criteria, strategies, and research issues of context-aware ubiquitous learning, and identifies the necessary check items as well for the development of such learning environment. Illustrative examples of conducting context-aware ubiquitous learning activities and the requirements of setting up such learning environment are also presented at the end of this paper.

Criteria, Strategies and Research Issues of Context-Aware Ubiquitous Learning

Context-aware ubiquitous learning (u-learning) is an innovative approach that integrates wireless, mobile, and context-awareness technologies to detect the situation of learners in the real world and provide adaptive support or guidance accordingly. In this paper, a context-aware u-learning environment is developed for guiding inexperienced researchers to practice single-crystal X-ray diffraction operations. Experimental results showed that the benefits of this innovative approach are that it is ''systematic'', ''authentic'', and ''economical'', which implies the potential of applying it to complex science experiments, such as physics, chemistry or biotechnology experiments, for graduate and PhD students in colleges, or research workers in research institutes.

A context-aware ubiquitous learning environment for conducting complex science experiments

In a method for delivering targeted television advertisements based on online behavior, IP addresses indicating online access devices and IP addresses indicating television set-top boxes are electronically associated for a multitude of users. Using user profile information derived from online activity from one of the online access IP addresses, a television advertisement is selected, such as by using behavioral targeting or demographic information, and automatically directed to the set-top box indicated by the set-top IP address associated with that online access IP address. Preferably neither the user profile information nor the electronic association of online access and set-top box IP addresses includes personally identifiable information.

Targeted television advertisements based on online behavior

Intended for network-wide dissemination of commands, configurations and code binaries, flooding has been investigated extensively in wireless networks. However, little work has yet been done on low-duty-cycle wireless sensor networks in which nodes stay asleep most of time and wake up asynchronously. In this type of network, a broadcasting packet is rarely received by multiple nodes simultaneously, a unique constraining feature that makes existing solutions unsuitable. Combined with unreliable links, flooding in low-duty-cycle networks is a new challenging issue.In this paper, we introduce Opportunistic Flooding, a novel design tailored for low-duty-cycle networks with unreliable wireless links and predetermined working schedules. The key idea is to make probabilistic forwarding decisions at a sender based on the delay distribution of next-hop nodes. Only opportunistically early packets are forwarded using links outside the energy optimal tree to reduce the flooding delay and redundancy in transmission. To improve performance further, we propose a forwarder selection method to alleviate the hidden terminal problem and a link-quality-based backoff method to resolve simultaneous forwarding operations. We evaluate Opportunistic Flooding with extensive simulation and a test-bed implementation consisting of 30 MicaZ nodes. Evaluation shows our design is close to the optimal performance achievable by oracle flooding designs. Compared with improved traditional flooding, our design achieves significantly shorter flooding delay while consuming only 20% ~ 60% of the transmission energy in various low-duty-cycle network settings.

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Opportunistic flooding in low-duty-cycle wireless sensor networks with unreliable links

With the growing interest in the use of autonomous computing, sensing and actuating devices for various applications such as smart grids, home networking, smart environments and cities, health care, and machine-to-machine (M2M) communication has become an important networking paradigm. However, in order to fully exploit the applications facilitated by M2M communications, adequate support from all layers in the network stack must first be provided in order to meet their service requirements. This paper presents a survey of the requirements, technical challenges, and existing work on medium access control (MAC) layer protocols for supporting M2M communications. This paper first describes the issues related to efficient, scalable, and fair channel access for M2M communications. Then, in addition to protocols that have been developed specifically for M2M communications, this paper reviews existing MAC protocols and their applicability to M2M communications. This survey paper then discusses ongoing standardization efforts and open problems for future research in this area.

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A Survey of MAC Layer Issues and Protocols for Machine-to-Machine Communications

In this paper we propose a TDMA slot assignment protocol to improve the channel utilization, which controls the excessive increase of unassigned slots by changing the frame length dynamically. Our proposed protocol assigns one of the unassigned slots to a node which joins the network. If there are no unassigned slots available, our proposed protocol generates unassigned slots by depriving one of the multiple slots assigned to a node, or enlarging frame length of nodes which can cause collision with each other. Moreover, by setting frame length as a power of 2 slots, our proposed protocol provides the collision-free packet transmission among nodes with different frame length. The simulation results show that our proposed protocol improves the channel utilization dramatically as compared with the conventional protocols.

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Dynamic TDMA slot assignment in ad hoc networks

Cellular phones are widely used to access the WWW. However, most available Web pages are designed for desktop PCs. Cellular phones only have small screens and poor interfaces, and thus, it is inconvenient to browse such large sized pages. In addition, cellular phone users browse Web pages in various situations, so that appropriate presentation styles for Web pages depend on users' situations. In this paper, we propose a novel Web browsing system for cellular phones that allocates various functions for Web browsing on each numerical key of a cellular phone. Users can browse Web pages comfortably, selecting appropriate functions according to their situations by pushing a single button.

OPA browser: a web browser for cellular phone users

We propose a method for selecting appropriate data based on personal information of mobile users to improve the success rate for requesting data in a ubiquitous computing environment. With this method, the output data is selected based on users' requirements. Then, a ubiquitous terminal that actually outputs the selected data is selected based on the facility and activity level of all terminals and the category of the selected data. As a result, our method can output effective data for mobile users in a ubiquitous computing environment where there are many types of data and ubiquitous terminals. Furthermore, we show the effectiveness of our method by a simulation experiment.

A method for selecting output data from ubiquitous terminals in a ubiquitous computing environment

Cellular phones have become popular and have been recognized as light-weight portable computers because of their various advanced functions such as E-mail, WWW browsing, and schedule management. However, since they are too small to display a large amount of information, users cannot make use of them as conveniently as normal computers. To solve this problem, we propose a remote display environment. In a remote display environment, there are large displays every- where in the real world, which we call remote displays. A user makes use of a cellular phone as a remote controller to display information on a remote display. We also describe our implementation of a WWW browsing system as an application in a remote display environment. Moreover, we describe our design and implementation of an access control mechanism by assuming applications in which multiple users simultaneously access one remote display.

A remote display environment: an integration of mobile and ubiquitous computing environments

In this paper, we describe our design and implementation of an information browsing system using Java-based cellular phones in a remote display environment which we have proposed. In this system, an application on a remote display displays various information for users, and a Java application on a cellular phone displays operational pages for users to operate the application on the remote display. Users can operate the application and browse information on the remote display by operating the corresponding operational pages on the cellular phone.

Toshiaki Uemukai

Papers

Dynamic TDMA slot assignment in ad hoc networks

OPA browser: a web browser for cellular phone users

A method for selecting output data from ubiquitous terminals in a ubiquitous computing environment

A remote display environment: an integration of mobile and ubiquitous computing environments

A Java-based information browsing system in a remote display environment