Study of Teaching Materials on Demand Using Space Collaboration System

本研究的目的是开发向大学提供学习资料的数据传输系统，这是扩展大学间卫星网络作为下一代高等教育基础设施的强烈需求。传输控制协议(传输控制协议)适用于点对点连接，但由于传输过程中的往返时间较长，具有吞吐量效率低的特点。为此，我们使用了UDP(用户数据报协议)，实现了可靠的数据传输，实现了与SCS多个VSAT站点之间的组播文件传输方案。设计的数据传输系统可以通过局域网传输任意教室的数据。要在SCS房间外的房间使用SCS，必须进行远程控制。然后我们开发了可以在远程机房操作的链路控制系统，SCS每年增加VSAT站点，扩大网络。人们已经认识到，SCS是日本远程教育的重要网络。同时会话的数量也会增加，这会导致预算问题。尽管图像质量和仪器操作已被评估为合理，但在技术和业务事项上仍有若干改进SCS的要求。我们希望数据传输服务将继续有力地支持SCS用户。

The purpose of this research was to develop data transmission system for provide learning materials with universities, which was strongly required to extend Inter-University Satellite Network, "Space Collaboration System" as an infrastructure of the next generation in higher education. TCP (Transmission Control Protocol) is suitable for point-to-point connection, however, it has feature of bad throughput efficiency because of large round trip time in propagation. So, we have used UDP (User Datagram Protocol), and achieved reliable data transmission, implementing a multicast file transfer program with several VSAT stations of the SCS.Extension of the SCS needed remote use in the same campus. The data transmission system has been designed to transfer data from any lecture room through local area network. Remote control was necessary for using the SCS at the room outside the SCS room. We have then developed the link control system which can be operated at the distance room.The SCS increases the VSAT stations every year, expanding the network. It has been recognized that the SCS is an important network for distance education in Japan. The number of simultaneous session will also go up, and this causes a budget problem. There are several requirements to improve the SCS in technical and operational matters, though the quality of images and the operation of instruments have been evaluated as reasonable. We hope that the data transmission service will continue to support the SCS users strongly.