Kazutaka Murakami

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In self-healing networks, end-to-end restoration schemes have been considered more advantageous than line restoration schemes because of a possible cost reduction of the total capacity to construct a fully restorable network. This paper clarifies the benefit of end-to-end restoration schemes quantitatively through a comparative analysis of the minimum link(More)
—Internet telephony is viewed as an emerging technology not only for wireline networks, but also for third generation wireless networks. Although IP end-to-end is considered the ultimate approach for future wireless voice services, there is still a long way to go before IP voice packets can be effectively transported over the air. Therefore, Internet(More)
— Session-based IP applications, such as Internet telephony, are an important component of the emerging mobile Internet. The ubiquitous availability of these services is critical to the success of the mobile Internet. Because all-IP networks will be deployed in phases and current mobile telecommunication systems will be in operation for decades to come, the(More)
Internet telephony and mobile telephony are both growing very rapidly. Directly interworking the two presents significant advantages over connecting them through an intermediate PSTN link. We propose three novel schemes for the most complex aspect of the interworking: call delivery from an Internet telephony (SIP) terminal to a mobile telephony (UMTS)(More)
This paper presents the design of a highly available distributed call processing system and its implementation on a local area network of commercial, off-the-shelf workstations. A major challenge of using off-the-shelf components is meeting the strict performance and availability requirements in place for existing public telecommunications systems in a(More)
Seamless roaming in heterogeneous circuit-switched and IP networks is key for successful migration towards all-IP. The Unified Mobility Manager (UMM) keeps track of users' locations whatever network they are roaming, and that routes calls from any originating to any terminating network. In a UMM enabled network, calls are addressed to users and dynamically(More)