Hirofumi Urayama

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This paper addresses requirements for emergency communication in a roadside-to-vehicle communication (RVC) system for vehicle safety, and proposes a new media access control (MAC) protocol, which meets both providing multi-applications and prioritizing emergency communication. The proposed technique utilizes two channels. One uses 5.8 GHz band assigned for(More)
This paper reports our recent result in designing a function for autonomous APs to estimate throughput and delay of its clients in 2.4GHz WiFi channels to support those APs' dynamic channel selection. Our function takes as inputs the traffic volume and strength of signals emitted from nearby interference APs as well as the target AP's traffic volume. By(More)
This paper presents a strategy to choose WiFi channels in urban areas. We consider (i) inter-channel interference where adjacent channels interfere with each other in WiFi systems and (ii) urban situations where many APs in different systems are deployed in an uncoordinated way. As it is often hard to identify the channel with less interference in such a(More)
This paper presents a scheduling algorithm for a set of wireless stations such as road-side access points for vehicular networks and outdoor WiFi stations, which are deployed in wide urban areas and may compete with each other for limited wireless resources. Different from a number of conventional approaches most of which consider detailed information on(More)
We describe capillary zone electrophoresis (CZE) for the simultaneous determination of bromide, nitrite and nitrate ions in seawater. Artificial seawater was adopted as the carrier solution to eliminate the interference of high concentrations of salts in seawater. The artificial seawater was free from bromide ion to enable the determination of bromide ion(More)
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