Haruki Izumikawa

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TCP is a popular Internet protocol for reliable end-to-end data delivery, but it cannot be directly applied to wireless networks in which packet loss may be induced by higher BER or handover than congestion. TCP assumes that such packet loss is caused by network congestion and initiates congestion control procedures. In this paper, we present a novel(More)
We present a robust cellular network (RoCNet) that combines a cellular and an opportunistic networks for spatial uplink mobile data offloading, which focuses on the spatial difference of the traffic load among areas (e.g., business district and residential area in the daytime). RoCNet realizes the spatial data offload by leveraging the store-carry-forward(More)
In sparse mobile networks, opportunistic access can be used to forward data in a so-called "store-carry-forward" manner using DelaylDisruption Tolerant Networking (DTN) techniques. In such environments, it is not always the case that a mobile terminal is within the communication range of other mobile terminals. Therefore, the terminal must first perform the(More)
out of the several available as well as perform vertical handover, which can be considered to be one of the key features of IMT-Advanced. We now have a dual-mode mobile terminal (MT) which can connect to both wireless LAN (WLAN) and cellular NWs, featuring a high transmission rate and wide coverage area, respectively. Before selecting and switching access(More)
The growing popularity of mobile data communication has been leading a growing lack of radio resource on a cellular network. Therefore, to avoid the data traffic from exceeding the capacity limit of a cellular base station (BS), cellular operators have been trying to install cellular femto cells (local BSs) or wireless LAN access points (APs) in(More)
Because a huge number of base stations are deployed due to the recent development of mobile access services, network monitoring in mobile networks becomes more challenging. In this paper, we propose a novel change-point detection scheme to efficiently detect a time instant (change-point) when the spatial distribution of mobile terminals connecting to base(More)