文章在开始时对 2 0世纪通信演变过程作简单回顾 ,接着讲到 90年代中期发生的重大转折和国际上对未来通信的重要预测 ,再依次描述 2 1世纪即将形成的通信网结构、光纤传输线路、全光通信网 ,以及蜂窝网和卫星移动通信。最后提出通信建设发展趋势的两个明显标志 The article begins with a brief review of the evolution of communications in the 20 th century. It goes on to talk about major changes that took place in the mid-1990s and important international projections of future communications. The article will next describe the forthcoming formation of communications networks in the 21st century. Optical fiber transmission Line, all optical communication network, and cellular network and satellite mobile communication. Finally, we put forward two obvious signs of the development trend of communications construction