1. A method performed by a base station in a wireless communication system, the method comprising:receiving, from a first terminal, first channel information corresponding to a first carrier and second channel information corresponding to a second carrier;
identifying first buffer usage for the first carrier from buffer occupancy (BO) of the first terminal based on the first channel information;
identifying second buffer usage for the second carrier from a remaining of the BO excluding the first buffer usage based on the second channel information;
allocating resources corresponding to the first buffer usage to the first carrier; and
allocating resources corresponding to the second buffer usage to the second carrier.