The signal transmission method according to the present invention comprises: determining the beam width of a beam to be transmitted; based on the beam width, determining relative narrowband transmit power (RNTP) information indicating whether or not to transmit, to a preset resource block, transmission power equal to or greater than a preset critical value; transmitting the RNTP information to an adjacent cell; and transmitting the generated beam to the resource block according to the RNTP information. Accordingly, provided is a method for setting a relative narrowband transmit power (RNTP) value so as to control interference between cells in a communication system.