Telecommunication technologies have been evolving toward broadband and ubiquitous networks at a very fast pace. In the future this evolution will lead to a ubiquitous network society, where anyone can be networked at anytime in anyplace and various services will be provided to enrich the human life. This dream of telecommunications will come true before long.
 

In the forthcoming ubiquitous network society era, communication services are expected to become increasingly convenient and accessible with high-speed Internet access from vehicles, ships and aircrafts, highly accurate positioning and time information acquisition services for mobiles and pedestrians, and remote control of electric appliances at home from outside.
 

How can we construct truly ubiquitous networks? The ubiquitous network environment is coming close to be real in urban areas, due to the rapid growth of terrestrial broadband communication services by optical fiber networks, cellular phone network, and high-speed wireless LAN provided in those areas. On the other hand, there still exist many places with insufficient communication services because of geographical and economical barriers. In addition, destruction of communication network infrastructures by natural disasters such as earthquakes and tsunamis are to cause enormous damages to social life both physically and economically. These problems need to be settled to move on toward a truly ubiquitous network society, where satellite systems are expected to play a prominent role.
 

Satellite systems for communications, broadcasting, and positioning services have unique features such as wide coverage, resistance to natural disasters, and capability of flexible services from the space. By taking advantage of systems including low earth orbit satellite systems and multi-beam satellite systems, various advanced satellite technologies have been developed. New satellite technologies also continue to be developed contributing to future ubiquitous network infrastructures, where satellite systems are used not only to supplement terrestrial networks but also to create new applications.
 

The 25^th AIAA International Communications Satellite Systems Conference (ICSSC-2007) will focus on the theme of "Evolution Toward a Ubiquitous Network Society". ICSSC-2007 will explore the evolutional directions of advanced satellite technologies as well as the possible means to vitalize satellite markets by new technologies toward a ubiquitous network society.