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学位取得年度	2003年度
氏名	湧川 隆次 (WAKIKAWA, Ryuji)
論文題目	モバイルインターネットのためのネットワークアーキテクチャの設計と実装
論文要旨	In this dissertation, architecture and protocols are studied and advocated for the universal mobile Internet. As mobile entities will become an integral part of the Internet in terms of their number, the current Internet architecture needs to be evolved. According to the proposed principles of the mobile Internet architecture, the current mobility technology such as Mobile IPv6 and the Basic NEMO protocol lack features of always-on connectivity, optimal routing, architectural robustness and scalability. The universal mobile architecture is an architecture which fulfills all the features proposed in the principle of mobile Internet architecture. The universal mobile Internet architecture is designed for all IP wireless communication infrastructure with the concept of {\it Smart End, Intelligent Edge, and Simple Robust Backbone}. Each mobile node obtains intelligence to adapt to visiting network dynamically with help of edge network. Edge network that contains access routers and wireless systems such as GSM, GPRS, W-CDMA, etc provides fast handover processing and wireless connectivity. Backbone network are kept simple to accommodate a large number of mobile nodes. Along with the concept, three new solutions: (1) multi-access, (2)virtual mobility control domain, and (3) ad-hoc managements, are proposed for the universal mobile Internet. As a result, the universal mobile Internet is realized supporting always-on connectivity, optimal routing, architectural robustness and scalability. The multi-access support provides always-on Internet connectivity and efficient communication scheme. A mobile node has various network interfaces and accesses to the Internet by selecting available interfaces depending on visiting networks. However, the current mobility protocols prohibit activating multiple connectivity simultaneously. With our proposal, the mobile node acquires care-of addresses on all the available interfaces and registers them to its home agent and correspondent nodes as the bindings of the same home address. The mobile node, then, sends and receives particular flows at the most appropriate interface depending on local policy. The evaluations show the multi-access solution improves communication performance and provides durable Internet connectivity. The virtual mobility control domain provides architectural robustness and optimal communication that are underlying principles of the mobile Internet architecture. The existing mobility protocols rely on single anchor point called home agent. The single home agent causes fatal performance decline due to overload of packet processing and system failure for mobile nodes; this is called single point of failure. Furthermore, the general Internet routing mechanism imposes redundant routes between end mobile nodes due to the dogleg routing. The proposed virtual mobility control domain enables mobility protocols to place multiple anchor points anywhere on the Internet despite the topology relationship. It consists of two new protocols, they are, the inter home agents protocol and the optimized route cache protocol. The inter home agents protocol activates multiple home agents for a same mobile node simultaneously. In the protocol, registered binding is implicitly synchronized among home agents without having mobile nodes aware of it. Alternatively, the optimized route cache protocol is introduced to activate an anchor point called correspondent router on-demand. The mobile node dynamically discovers a correspondent router and explicitly registers its binding. The correspondent router, then, acts as an anchor point on behalf of the home agent. The virtual mobility control domain is proved to provide robustness of mobility protocols and optimal communication with anchor points distribution in our evaluation. It can be concluded that the general Internet routing mechanism needs to interact with the virtual mobility control domain in terms of the best anchor point selection for optimal routing on the universal mobile Internet. The ad-hoc managements are exclusive features of the universal mobile Internet architecture. They are Internet connectivity and direct connectivity establishments by using mobile ad-hoc network (MANET) routing protocol. When a mobile node loses connectivity to the Internet, it dynamically discovers an adjacent Internet Gateway that provides Internet connectivity for mobile ad-hoc networks. After IPv6 global address resolution and route setup for the Internet Gateway, the mobile node accesses the Internet via the Internet Gateway on multihop wireless networks. Meanwhile, the Internet Gateways support the Basic NEMO protocol, it will possibly have two routes for a destination. One of them will be a route via home agent and the Internet, called the NEMO route, and the other is a direct route through intermediate nodes within MANET, called a MANET route. When a mobile node moves closely to a destination node, it locally discovers MANET routes and communicates without using the Internet infrastructure. The mobile node needs to select MANET routes only while the routes are shorter and faster than NEMO routes. Simulation work confirms better performance with MANET routes than NEMO routes in terms of round trip time. As a result, this dissertation contributes to design the universal mobile Internet architecture supporting scalability, robustness and performance improvements. The mobile Internet architecture encompasses diversity of mobile environments and keeps consistency with the existing Internet. This universal mobile Internet will be a common infrastructure of mobile computing and pioneers mobile industry.
連絡先	本文が必要な場合は下記までご連絡ください。 湧川 隆次 (ryuji@sfc.wide.ad.jp )

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