1、前言近几年来,由于电子技术的进步及电信的发展给活跃社会经济带来了巨大的变化,对电信的需求急剧地增加,同时,电信的应用日趋高级和多样。在这种形势下,无线通信,特别是移动通信的应用有了显著的增长,1985年3月在总数为330万台的无线电台中,移动台占95％。其用途从确保船舶、飞 1. Introduction In recent years, the demand for telecommunications has dramatically increased due to the tremendous changes brought about by the progress of electronic technology and the development of telecommunications in the active socio-economy. At the same time, the application of telecommunications has become increasingly advanced and diverse. Under such circumstances, there has been a remarkable increase in the use of wireless communications, especially in mobile communications. In March 1985, a total of 3.3 million radio stations accounted for 95% of mobile stations. Its use from ensuring the ship to fly