Methods and apparatus are provided for transmitting channel quality information. User equipment receives a control signaling for uplink scheduling. The control signaling for uplink scheduling includes at least one modulation and coding scheme (MCS) field, a channel quality information request field, and a resource block allocation field indicating the number of resource blocks (RBs), NRB, allocated to the user equipment for transmitting the channel quality information. When the channel quality information of multiple downlink carriers is requested, the user equipment transmits only the channel quality information on the uplink shared channel according to the allocated RBs if: the MCS bit field corresponding to one transport block indicates a MCS corresponding to a retransmitted data packet; the request bit field indicates a request for the channel quality information; and the NRB is equal to or less than 4*N, wherein N is a positive integer and corresponds to the number of multiple downlink carriers.