Naoki Imai

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Supporting Quality of Service (QoS) in a core transport is an important feature of a next generation network. This feature not only enables real-time communication services such as Voice over IP (VoIP) and video telephony, but also helps create new applications. However, access gateway such as Packet Data Gateway (PDG) in IMS WLAN Interworking, located at(More)
In the future, wireless access networks will diversify, and they are quite different in their characteristics. We focus on data transmission rate and area coverage, and assume overlay network composed of hot-spotted network and cellular network. Hot-spotted network indicates high-speed wireless network and very limited communication area due to its spotted(More)
This paper proposes a media synchronization method for real-time group communication within a multiple device environment. The method controls the output time of each media unit received at multiple devices and synchronizes them, even if the arrival time of the media unit temporarily fluctuates. This fluctuation is caused by variation in bandwidth and the(More)
Dual-mode cellular phones, including smartphones, are recently attracting much attention from both users and telecom operators throughout many countries. To avoid traffic concentration generated by these devices on 3G networks, it is important to lead users to connect with fixed networks via WLAN. However, keeping both 3G and WLAN interfaces on consumes a(More)
Multi-device communication will be usual in a ubiquitous networking environment with features of heterogeneity and ubiquity. Under such circumstances, users shall be able to communicate via a method optimized based on their surroundings and preferences. This paper shows a dynamic session modification mechanism that enables users to switch their(More)