A description of the operation of FIG. 4A is omitted because the operation is redundant with that of the first embodiment. Referring to FIG. 4B, operation 410 shows an example in which two BPLs have been established through SRS-based UL BM. In this case, it is assumed that an SRS #1-based BPL 411 is used for DL transmission and an SRS #2-based BPL 413 is used for UL transmission. Next, operation 420 is a process for a base station to perform indication necessary for an UL-DL reciprocal beam association with respect to a terminal. Operation 430 is a process for the terminal to perform DL transmission by applying a DL BPL based on the received indication. In this case, the DL BPL may be applied to a DL CSI-RS, a DL DMRS, a PDCCH or a PDSCH.

FIG. 5A is a diagram showing a procedure of a base station for a DL-UL reciprocal beam association according to a second embodiment of the disclosure.

Referring to FIG. 5A, at operation 501 the base station may receive information indicating whether the BC of a terminal has been established. At operation 503, the base station may determine whether or not to perform BM for the DL transmission of the base station and the UL transmission of the terminal. If the base station has performed DL BM at operation 505, it proceeds to operation 521. If the base station has not performed DL BM, it proceeds to operation 507. Furthermore, if the base station has performed UL BM at operation 521, it proceeds to operation 531. If the base station has not performed UL BM at operation 521, it proceeds to operation 523. The sequence of operation 505 and operation 521 may be exchanged.