In the case of a disaster such as an earthquake or a tsunami, the city, town, and village administration usually issues an evacuation advisory and other information through the Outdoor Public Address Speakers for the disaster reduction broadcasting system covering its area of jurisdiction. However, in areas those have previous experience of a disaster, people frequently voice the lack of audibility of the disaster reduction broadcast. In this research, we conducted a questionnaire survey on the residents in the central area of Ishinomaki City, Miyagi Prefecture, who are the victims of the Great East Japan Earthquake Disaster, on the audible quality of outdoor public address (PA) speakers of the disaster reduction broadcasting system so as to understand the current state of such broadcasts and to propose ideal methods of sending and receiving information at the time of a future disaster.

This paper proposes an adaptive transmission control method for massive and intensive telecommunication traffic generated by communication-broadcasting integrated services. The proposed method adaptively controls data transmissions from viewers depending on the congestion states, so that severe congestion can be effectively avoided. Furthermore, it utilizes the broadcasting channel which is not only scalable, but also reliable for controlling the responses from vast numbers of viewers. The performance of the proposed method is evaluated through experiments on a test bed where approximately one million viewers are emulated. The obtained results quantitatively demonstrate the performance of the proposed method and its effectiveness under massive and intensive traffic conditions.

We propose an IP broadcasting system architecture using passive optical networks (PON) utilizing the optical broadcast links of a PON with a downstream bandwidth allocation algorithm to provide a multi-channel IP broadcasting service to home subscribers on single broadband IP network infrastructures. We introduce the design and adaptation of the optical broadcast links to effectively broadcast video contents to home subscribers. We present a performance analysis that includes the downstream bandwidth utilization efficiency of the broadcast link and the bandwidth control of the IP broadcasting and Internet data. Our analysis and simulation results show that the proposed system can provide 100 HDTV channels to every user over fiber lines. We also propose an IPTV channel selection mechanism in an ONT by selecting a broadcast stream. We developed and evaluated a prototype that can achieve a 15-msec IPTV channel selection speed.