A method of transmitting channel quality indicator (CQI) includes obtaining CQI of each, of the plurality of sub-bands, selecting a first sub-band having the best CQI of the plurality of sub-bands, transmitting the best CQI of the first sub-band at a first transmission cycle and transmitting a difference value between the best CQI of the first sub-band and a CQI of the first sub-band at a second transmission cycle. Signalling overhead due to CQI transmission can be reduced.