A method for transmitting downlink data using resource blocks at a base station in a wireless mobile communication system includes transmitting downlink data mapped to physical resource blocks (PRBs) to a user equipment, wherein indexes of virtual resource blocks (VRBs) are mapped to indexes of the PRBs for a first slot and a second slot of a subframe, and the indexes of the PRBs for the second slot are shifted with respect to the indexes of the PRBs for the first slot based on a predetermined gap, and wherein a predetermined offset is applied to an index of a PRB when the index of the PRB is equal to or greater than a predetermined threshold.