2 Technologies for emergency communication networks: 2-1 for high availability of mobile phone-researches on network control technologies in disasters

Mobile phones come into wide use now and many people usually carry about and are familiar with using them. So, mobile phone becomes a very useful communication tool in large scale disasters. But it often cannot use, because congestion occurs owing to large demand of calls by which people wants to know their family with accidents or without accidents, non-functional base stations occur owing to cable cutting or long time power failure. As countermeasures to these issues, we study the holding time limitation and the emergency multi-system access, in the project of researches on network control technologies in disasters. This paper describes the outline of our studies.