Toshiaki Uemukai

Dynamic TDMA slot assignment in ad hoc networks

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.

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

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 web browsing system for cellular-phone users based on adaptive presentation

Cellular phones are widely used to access the Web. However, most available Web pages are designed for desktop PCs, and it is inconvenient to browse these large Web pages on a cellular phone with a small screen and poor interfaces. Users who browse a Web page on a cellular phone have to scroll through the whole page to find the desired content, and must then search and scroll within that content in detail to get useful information. This paper describes the design and implementation of a novel Web browsing system for cellular phones. This system includes a Web page overview to reduce scrolling operations when finding objective content within the page. Furthermore, it adaptively presents content according to its characteristics to reduce burdensome operations when searching within content.

A web browsing system based on adaptive presentation of web contents for cellular phones

Cellular phones have already been widely used to access the Web. However, most existing Web pages are designed for desktop PCs, and thus, it is inconvenient to browse these large Web pages on a cellular phone with a small screen and poor interfaces. Users who browse a Web page on a cellular phone have to scroll the whole page to find an objective content, and then, have to scroll within the content in detail to get useful information. In this paper, we propose a novel browsing system to break off these burdensome operations by adaptively presenting Web contents according to their characteristics.

Content description and partitioning methods for collaborative browsing by multiple mobile users

In a mobile computing environment, low functionality of handheld devices restricts services provided for mobile users. We have proposed a concept of collaborative browsing where mobile users collaboratively browse a rich Web page designed for desktop PCs that cannot be displayed on one device. In collaborative browsing, a rich Web page is divided into multiple partial pages and then each of them is distributed to each device. In this paper, we propose a content description method to realize collaborative browsing. We also describe a content partitioning method, by which contents described in the content description method are divided into multiple sets of objects.

A content search system considering the activity and context of a mobile user

People routinely carry mobile devices in their daily lives and obtain a variety of information from the Internet in many different situations. In searching for information (content) with a mobile device, a user’s activity (e.g., moving or stationary) and context (e.g., commuting in the morning or going downtown in the evening) often change, and such changes can affect the user’s degree of concentration on his or her mobile device’s display and information needs. Therefore, a search system should provide the user with an amount of information suitable for the current activity and a type of information suitable for the current context. In this study, we present the design and implementation of a content search system that considers a mobile user’s activity and context, with the goal of reducing the user’s operation load for content search. The proposed system switches between two kinds of content search systems according to the user’s activity: the location-based content search system is activated when the user is stationary (e.g., standing and sitting), while a menu-based content search system is activated when the user is moving (e.g., walking). Both systems present information according to user context. The location-based system presents detailed information via menus and a map according to location-based categories. The menu-based system presents only a few options to enable users to get content easily. Through user experiments, we confirmed that participants could get desired information more easily with this system than with a commercial search system.

Content comparison functions for mobile co-located collaborative web search

Due to the recent popularization of mobile devices, such as mobile phones and PDAs, most people have their own mobile devices in Japan. In this situation, a user can search the Web not only by himself, but together with his friends and families, which aims to find information that meets requirements from all of them. In such collaborative search, users first search the Web separately and collect contents of interest, and then, share the contents with others by showing a screen with each other. However, because mobile devices generally have a small screen, this process is burdensome for users. In this paper, to solve this problem, we propose an interface to support users engaged in collaborative search to share and compare their collected contents. The proposed interface provides functionalities to effectively share contents collected by all members and to add reviews in order to make content search and comparison easier.

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

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.

Nine-Button Web Browsing System for Cellular Phone Users

Cellular phones are widely used to access the Web. However, most available Web pages are designed for desktop PCs, and it is inconvenient to browse these large Web pages on a cellular phone with a small screen and poor interfaces. Users who carry cellular phones browse Web pages in various situations. Therefore, appropriate browsing styles are different based on their situations. In this paper, we propose a novel Web browsing system called nine-button browsing system, in which numerical keys of cellular phone have different functions for presenting Web pages. This system enables users to browse Web pages comfortably adapting their situations

A Content Clipping System for Web Browsing Using Cellular Phones

While Bookmark and Screen-memo memorize Web pages for future re-visit, re-visiting Web pages by using Bookmark or Screen-memo still requires a large amount of operation for cellular-phone users since the screen sizes of cellular phones are generally much smaller than the sizes of Web pages. In this paper, we describe the design and implementation of a content clipping system for Web browsing using cellular phones. This system presents multiple candidates for clipping a content, then, mobile users can easily specify the clipped target. Moreover, this system semi-automatically generates tags attached to the contents and automatically classifies the clipped contents. By using this system, users can easily specify contents of interest in Web pages and re-visit them with simple operations.