the present invention discloses a base station system , including an indoor part and a remote rf subsystem . the indoor part includes a riu , a ccu , a bbu , a gpsu and a local interface unit . the rrs includes a remote interface unit , a rf transceiver unit and an antenna . the local interface unit and the remote interface unit are for signal intercommunicating between the indoor part of the base station and the rss . the tru is a rf transceiver module of the conventional rfu , for amplifying an analog rf signal from the remote interface unit and transmitting the signal to the antenna . by flexibly selecting between an optical cable and an if cable , the interface unit of the present invention provides a digital baseband remote manner and an if remote manner . according to the structure of the base station of the present invention , the number of the base station sites and the network operating cost decreases ; on the other side , since one base station may cover a cell by smart antenna with only one optical cable or if cable , the difficulty in mounting is reduced .