Abstract: A multicarrier communication system divides a full frequency band into a plurality of sub-carrier frequency bands, generates a plurality of segments having a frequency-time domain occupied by a predetermined number of sub-frequency bands and a predetermined number of time intervals, and classifies a plurality of segment types according to each of the segments, for data transmission. A mobile subscriber (MS) measures a channel state, extracts channel state information corresponding to the channel state, estimates a segment type using the extracted channel state information, and determines whether there is a need for a change in a segment type allocated to the MS itself. If there is a need for a change in the segment type, the MS transmits a segment type change request message to a base station (BS). Upon receiving a segment type change grant message from the BS in response to the segment type change request message, the MS receives data in a segment type corresponding to the received message.