The difficulty is primarily due to the lack of line of site between base stations, or towers, and the subscriber.

困难主要是在基站（或者发射塔）与用户之间缺乏直达线路。

youdao

A wireless communications network (100) includes various base stations (100) and subscriber-stations (114).

一无线通信网络(100)包括多个基站(100)和订户站(114)。

youdao

A wireless communications network (100) includes various base stations (100) and subscriber-stations (114).

一无线通信网络(100)包括多个基站(100)和订户站(114)。

youdao