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Akifumi KASAMATSU Akio TANAKA Hiroshi KODAMA Satoru TANOI Yasuhiro KAIZAKI Juichi NAKADA Masami HAGIO Yoshiaki KURAISHI Keren LI Hitoshi UTAGAWA Toshiaki MATSUI Ryuji KOHNO
This paper shows activities of the ultra wideband (UWB) research and development consortium organized by the National Institute of Information and Communications Technology (NICT). Fully CMOS monolithic microwave integrate circuits (MMICs) are designed and fabricated both for the multiband OFDM and the impulse radio. UWB transceivers are constructed with the MMICs as their front-end devices and evaluated by some measurements such as time domain waveform, spectrum, error vector magnitude, and so on. To show the application capabilities of the UWB transceivers, two kinds of video transmission system are constructed and demonstrated.
Akio TANAKA Keisuke NAKANO Masakazu SENGOKU Shoji SHINODA
Wireless network systems introducing both of the cellular concept and the ad-hoc concept have been proposed. Communication between two nodes in a cell is guaranteed by relaying capability of the base station in these systems. Additionally, two nodes can directly communicate with each other while they are close to each other. We call this type of network a two-hop wireless network. The teletraffic performance of this network depends on various parameters such as the size of a cell, location of nodes, the communication range of nodes, channel assignment schemes, teletraffic behavior and so on. The purpose of this paper is to theoretically analyze the teletraffic performance of the network, which has been evaluated by computer simulation, by introducing a simple model. This paper shows a technique to analyze the performance in this model. Also, this paper considers the range in which the two-hop wireless network works well for the efficient use of channels.