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Akihito NAKAMURA Makoto TAKIZAWA
This paper discusses how to provide selective broadcast communication for a group of multiple entities in a distributed system by using high-speed communication networks. In the group communication, protocol data units (PDUs) sent by each entity have to be delivered atomically in some order to all the destinations in the group. In distributed applications, each entity sends a PDU only to a subset rather than all the entities, and each entity needs to receive all the PDUs destined to it from every entity in the same order as they are sent. We name such a broadcast service a selective order-preserving broadcast (SP) service. In this paper, we discuss how to design a distributed, asynchronous protocol which provides the SP service for entities.
Miki HASEYAMA Makoto TAKIZAWA Takashi YAMAMOTO
In this paper, a new video frame interpolation method based on image morphing for frame rate up-conversion is proposed. In this method, image features are extracted by Scale-Invariant Feature Transform in each frame, and their correspondence in two contiguous frames is then computed separately in foreground and background regions. By using the above two functions, the proposed method accurately generates interpolation frames and thus achieves frame rate up-conversion.
Miki HASEYAMA Daisuke IZUMI Makoto TAKIZAWA
A method for spatio-temporal resolution enhancement of video sequences based on super-resolution reconstruction is proposed. A new observation model is defined for accurate resolution enhancement, which enables subpixel motion in intermediate frames to be obtained. A modified optimization formula for obtaining a high-resolution sequence is also adopted.
Makoto TAKIZAWA Hiroto AIDA Masato SAITO Yoshito TOBE Hideyuki TOKUDA
In this paper, we present a novel forwarding scheme to enhance communication stability based on geographic routing in mobile ad hoc networks, which is called "Position-based Heuristic Forwarding" (PHF). For alternative solutions to traditional ad hoc routings, many geographic routing algorithms have been proposed. Most of the existing routings impose a certain restriction, planarity, on the graph structure of network for delivering messages to destination definitely. PHF achieves the guaranteed packet delivery over Unit Disk Graph, which is more widely employed graph model for the study of ad hoc networks. Accordingly, to eliminate the restriction of the routing algorithms enhances the probability to deliver messages successfully in networks with high nodes' mobility rate. In the simulation of PHF, we have evaluated the performance comparisons between PHF and its related work, Greedy Perimeter Stateless Routing (GPSR) and Dynamic Source Routing (DSR), which are the prominent geographic and conventional topology-based routing protocols, respectively. The results show that PHF provides higher packet delivery success rate indicating better communication stability and equal or less overhead than these work.