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This paper proposes an authentication technique by 3D pattern communication, using terminals with a small-sized screen. 3D pattern communication is a method whereby an arbitrary signal can be transmitted by rewriting the signal patterns on the screen for several times on the terminal screen. The signal is not limited by the display resolution of the screen or the kind of liquid crystal. Con- sequently, any signal can be sent to the destination through the screen, and secure authentication can be realized by using a portable terminal. It is verified that, even if the terminal is inclined to some extent during reading due to the angle of the hand holding the terminal, or an arbitrary picture is overlaid on the pattern, the 3D pattern can be recognized correctly by utilizing error-correcting code and interleaving. The proposed scheme is implemented on cur- rent models of portable phones with TFT, TFD, STN, and organic EL screens. The communication of 1024-bit RSA signature data is successfully performed in 0.33 to 0.44 second, except for a single terminal. Using the proposed 3D pattern communication, an authentication service with a strong security requirement can be provided without adding a special device to existing portable phone terminals. [ABSTRACT FROM AUTHOR]

Mobile computing, in which a small computer connected to a computer network by means of a mobile communication network can be carried by the user, is becoming possible. In the mobile computing environment, there occur problems specific to wireless communication that are not experienced in wired networks, such as disconnection of the communication channel and inability to make a connection. Also, the user may use computers other than his own portable one, depending on the location. In this paper, an agent platform that takes into account the characteristics of mobile computing is proposed. The proposed platform supplements the deficiencies of the wireless communication and provides an environment in which agents that support user mobility are available. © 1999 Scripta Technica, Electron Comm Jpn Pt 1, 82(11): 63–72, 1999 [ABSTRACT FROM AUTHOR]

An ad hoc LAN is a LAN which is temporarily formed of arbitrary stations at an arbitrary site. This paper discusses the Medium Access Control (MAC) scheme in the wireless LAN, from the viewpoint of station mobility and the basic aspect of the ad hoc LAN. In order to support the ad hoc LAN, it is desirable to apply the peer-to-peer MAC scheme, which does not require a particular infrastructure. In the peer-to-peer MAC scheme in general, however, performance degradation due to hidden terminals is a problem. Especially when the station is moved or an ad hoc LAN is formed near an existing service area, stable performance is difficult to realize. From such a viewpoint, this paper newly proposes the STMA/DA (single tone multiple access with directional antennas) peer-to-peer MAC scheme. STMA/DA utilizes the busy tone and the reservation mechanism, so that stable communication is secured even if there are hidden terminals. The geographical area occupied by the communication is minimized by using sector antennas, so that the number of simultaneous communications in the system can be increased. The performance of STMA/DA is evaluated by computer simulation. Through a comparison to CSMA and RI-BTMA, the effectiveness of STMA/DA is demonstrated. © 1999 Scripta Technica, Electron Comm Jpn Pt 1, 82(5): 74–84, 1999 [ABSTRACT FROM AUTHOR]

This paper proposes a host mobility support protocol (HMSP), a new protocol to support mobile host on the Internet. In the design of HMSP, it is intended that modifications of existing networks are held to a minimum, and scalability is realized so that operation is possible among multiple domains distributed over a relatively wide area. The concept of a virtual subnet is introduced into HMSP, and this can be set independently by the domains. The mobile host is assumed to exist on the virtual subnet. Support Host and Root Support Host are introduced as special routers to the virtual subnet and transparent communication to the mobile host is realized by encapsulization. © 1998 Scripta Technica. Electron Comm. Jpn. Pt 1, 81(5): 20–29, 1998 [ABSTRACT FROM AUTHOR]