Abstract
Recently, in Japan, crimes against children become atrocious and brutal. In some cases, children are attacked on the way to and back from school. Many technologies using ubiquitous networks have been developed to prevent crimes against children on their way to and back from school. Existing technologies, however, are not powerful to prevent crimes against children and helpful for parents since it is difficult to take information of children as a group. If the system can provide group information of children on the way to and back from school, it is easy for parents to know their safety level. This paper proposes a new technology for children tracking system based on mobile ad hoc networks and describes outline of children tracking system in Hiroshima City. The field experiments using the children tracking system have been performed and the effectiveness of the system is shown by data analysis for the experimental results.