关键词: 国际电信联盟, 卫星广播业务, 雨衰减

Abstract: By reviewing the progress of the modifications of the Planned BSS in the World (Radiocommunication) Conference and based on detailed transmission analysis,it is emphasized to considerthe various factors in the determination of space service polarizations,such as carrier transmission characteristics in defferent polarizations,combined space service applications,the(provisions) in the Planned BSS and the convenience of both spectrum coordination and the installation of the receiving equipment.