Yoshinori Sakai

Image information retrieval using rough set theory

We describe a method for automatically generating an image retrieval algorithm corresponding to keywords. The retrieval algorithm that we proposed consists of a scalar quantizer and discriminator and can be generated quickly and automatically by utilizing the idea of rough set theory. We demonstrated through experiments that the proposed method is effective to generate image retrieval algorithms.

QoS multicast protocol for live streaming

Live streaming media are delay sensitive and have limited allowable delays. Current conventional multicast protocols do not have a loss retransmission mechanism. Even though several reliable multicast protocols with retransmission mechanisms have been proposed, the long delay and high packet loss rate make them inefficient for live streaming. This paper proposes a multicast protocol focusing on the allowable delay called the QoS Multicast for Live Streaming (QMLS) protocol. QMLS routers are placed along the multicast tree to detect and retransmit lost packets. We propose a method that enables data recovery to be done immediately after lost packets are detected by the QMLS router and a method that reduces the unnecessary packets sent to end receivers. This paper discusses the mathematical analysis of the proposed protocol and compares it with other multicast protocols. The results reveal that our protocol is more effective in live streaming. Finally, we do a simulation to evaluate its performance and study the effect of consecutive losses. The simulation reveals that consecutive losses can slightly increase losses with our protocol.

A Proposal for a Multicast Protocol for Live Media

Live streaming media is delay sensitive with small allowable delay. Current conventional multicast protocols do not provide a loss retransmission mechanism. Even there are some researches on a reliable multicast providing a loss retransmission mechanism but a long delay and a high packet loss rate make them inefficient for live streaming. This paper proposes a new multicast protocol based on a protocol relay concept. The proposed protocol focusing on allowable delay provides Quality of Service (QoS) for live streaming. Relay nodes are placed along the multicast tree. Data recovery is done between relay nodes. We propose the methods that enable protocol relays to request retransmission immediately and reduce the number of duplicate packets. Finally, we make a mathematical analysis of the proposed protocol and compare it with other multicast protocols. The results show that the proposed protocol is more efficient for live streaming than the conventional protocols.

A scheme to reduce delay-overheads at the beginning of satellite network communication

Satellite communication technology has been looked to extending the terrestrial network to remote areas in years. It has been used for the purpose of providing a dedicated line from one to another or of broadcasting from a specified host. However the demand for a switching network such as the Internet, where a host communicates with one of a number of unspecified hosts, is increasing, and expectations are high that satellite technology is adapted. There are some problems when a satellite network is used as switching network. In this paper, we focus on delay allocation at the beginning of communication. For improving this delay-overhead, we propose a method of standby bandwidth. This method enables bandwidth allocation logically as independent from bandwidth reservation of a physical layer. First, we suggest the proposed method in a VSAT network, which is the most popular satellite network. Finally, we evaluate the proposed method in simulation and show that the proposed method performs reliably and effectively.

Effective content drifting method on content-based network using game theory

Content distribution networks (CDNs) are well known to be able to distribute many kinds of content on the Internet, where caches and mirror servers are used to store and distribute content. In this paper, we propose novel network architecture to distribute content, called a content-based network (CBN). Each unit of content in the CBN has meta-data including keys to retrieve content If meta-data has a parameter that indicates how often the content has recently been retrieved, we can select adequate operation (store content, delete content, move content, divide content, and merge content) considering network traffic, capacity in each node, and also the meta-data parameters. To achieve the above, we used the game theory. In this paper, two game players and gain are defined; content group player and neighboring nodes group player. Computer simulation revealed that the proposed algorithm has the capability of minimizing the number of hops to retrieve target content.

Design of the multi-channel communication system for the MPEG video data streams using adaptive QoS control

In this paper, we show a design method for a multi-channel communication system for MPEG video that is based on adaptive QoS control. The relation between the SNR degradation and the coded bitrate in each scene of a video channel is approximated by linear equation. The bitrate is allocated to each scene based on a linear equation. However, if the number of channels increases, the bitrate is not allocated appropriately because the scenes change frequently. In this paper, we divide the video channels into groups. An optimum number of groups can be obtained by considering the scene characteristics. Furthermore, we also show experimental results of applying the method to a prototype system.