A method for forming a subchannel in a communication system where a first communication system and a second communication system coexist. The method includes determining a first tile set by arranging first tiles remaining after forming at least one first subchannel for the first communication system among frequency resources, including a plurality of tiles, available for the first communication system; determining a second tile set by inserting second tiles which are independent of the frequency resources and are available for the second communication system into the determined first tile set at predetermined positions; forming at least one second subchannel for the second communication system by selecting a predetermined number of tiles from the second tile set; and performing communication using at least one of the first subchannel and the second subchannel.