FIG. 7A is a diagram showing a procedure of a base station for an UL-based beam association according to a third embodiment of the disclosure.

Referring to FIG. 7A, at operation 705 a base station may receive information indicating whether the BC of a terminal has been established. At operation 710, the base station determines whether or not to perform UL BM for DL transmission. At operation 715, the base station performs BM on the terminal. The base station may perform UL BM along with the terminal. The base station may obtain at least one BPL as a result of the execution of the UL BM.

At operation 720, the base station may determine whether to use UL BM for DL transmission. If the UL BM is not used, the base station may proceed to operation 725. If the UL BM is used, the base station may proceed to operation 740.

At operation 725, the base station may transmit indication regarding whether an UL-based DL beam association has been activated to the terminal. The indication may indicate the deactivation of the UL-based DL beam association. For a detailed operation, reference is made to the method of transmitting indication regarding whether an UL-based DL beam association has been activated, which has been described in the third embodiment. Operation may be omitted. If the DL-based UL beam association has been deactivated, the base station may perform DL BM along with the terminal at operation 730. At operation 735, the base station may transmit DL BM-based DL BPL indication to the terminal. For a detailed method of transmitting the DL BLP indication, reference is made to the operation of the third embodiment.