Hirokazu Yoshinaga

Coordinator election using the object model in p2p networks

We propose the ACE (Adaptive Coordinator Election) platform that elects and relocates a coordinator adaptively in P2P networks. In collaborative applications, a coordinator mediates synchronization, consistency, sequencing and delay difference. However, it is difficult to decide a coordinator in applications used in P2P networks because of some characteristics of network, e.g., network instability, and differences in physical networks and devices for participants. The ACE platform elects and relocates a coordinator dynamically according to environmental metrics obtained from participants. Each metric has a priority and weight to allow a coordinator to be chosen according to the purpose of applications. We implemented our platform using the JXTA framework and tested it. The results show the feasibility of adaptive coordinator relocation in P2P networks.

A Study on Scalable Object Replication Method for the Distributed Cooperative Storage System

Recently, a Peer-to-Peer (P2P) technology is applied for various systems because it enables to construct a system with high scalability and robustness.We have proposed a distributed cooperative storage system that can construct huge storage space by providing it on a P2P network.The storage system is based on an overlay network construction, and its hash space is created in an application layer.Each peer manages the certain range of the hash space, and an object is stored to suitable peers by using a hash value from the object.In the general P2P network, objects are replicated over many peers to achieve high availability.Some replicated methods have been proposed: objects are randomly assigned, assigned on a route path, or assigned to peers that the number of them is fixed by a network neighborhood depending on a distributed hash table.However, they are not so suitable since the scale of the network is not considered in these methods.Therefore, we propose distributed interval trees for setting the number suitably, and the availability is described with simulation.

Localization algorithms for distributed platform among vehicles

There are theoretical and empirical RSS-based algorithms proposed and many studies have been made by comparing the performance of these algorithms. However, there is a lack of theoretical basis and understanding on the orientation of vehicles without GPS. This paper presents a model for an orientation-aware location tracking manner for the detections of vehicles using wireless sensors based on IEEE 802.15.4 standard protocol. For path loss model, our experiment shows a better prediction of RSS when attenuation factors for different orientations are considered in the model. On the other hand, orientation-aware fingerprint algorithm, which currently stands as one of the most accurate RSS-based localization algorithm, is also examined in our experiment to have a basis of comparison with an empirical algorithm.

STARCast: streaming collaboration platform using the overlay technology

In this paper, we propose a streaming platform which we call the STARCast. This platform enables to provide streaming service by overcoming some of the limitations and complexities of current network environments. The STARCast node consists of two types of independent data plane, the one is streaming control plane, which manages some information for connection by the resource manager, the another is streaming data plane, which enables to transfer the all kinds of streaming data without relation of their kinds, and distribute it efficiency use of ALM (application layer multicast) which can be adapted the topology for the number of nodes and requirement from user application. The STARCast also enables adaptation to various types of address spaces such as those of NAT and IPv6, and various transport networks so that streaming services can be offered anywhere on the Internet. And this proposed platform enables to provide and receive the streaming service all over the Internet using any computers ubiquitously. As an function of the STARCast for streaming, we discuss the method for application layer multicast which enables to adapt node character and environment. In this paper, we show the its availability by the simulation.