First, if the base station has not performed DL BM at operation 505, the base station may perform UL BM at operation 507. At operation 509, the base station may transmit DL-UL reciprocal beam association indication to the terminal. At operation 511, the base station may transmit UL BM-based DL BPL indication and UL BM-based UL BPL indication to the terminal. For a detailed method of transmitting the indications at operation 509 and operation 511, reference is made to the detailed method of transmitting the indication described in the second embodiment. At operation 513, the base station may transmit a DL signal, a channel, data or control information to the terminal based on the UL BM-based DL BPL indication, and may receive an UL signal, a channel, data or control information from the terminal based on the UL BM-based UL BPL indication.

If the base station has performed DL BM at operation 505, it proceeds to operation 521. If the base station has not performed UL BM at operation 521, it proceeds to operation 523. At operation 523, the base station may transmit DL-UL reciprocal beam association indication to the terminal. At operation 525, the base station may transmit DL BM-based DL BPL indication and DL BM-based UL BPL indication to the terminal. For a detailed method of transmitting the indication at operation 523 and operation 525, reference is made to the detailed method of transmitting the indication described in the second embodiment. At operation 527, the base station may transmit a DL signal, a channel, data or control information from the terminal based on the DL BM-based DL BPL indication, and may receive an UL signal, a channel, data or control information based on the DL BM-based UL BPL indication.