Method and apparatus for reporting feedback information are disclosed. A wireless transmit/receive unit (WTRU) may receive a first control message including both information indicating a first allocation of resources on a first downlink transmission for a first downlink carrier and a first indication of resources for feedback corresponding to the first downlink transmission. Further, the first indication of resources for feedback may include at least one orthogonal frequency division multiplex (OFDM) symbol and at least one subcarrier. Moreover, the WTRU may receive the first downlink transmission in the first allocation of resources on the first downlink carrier. Also, the WTRU may derive acknowledgement/negative acknowledgement (ACK/NACK) feedback corresponding to the first downlink transmission. Additionally, the WTRU may transmit the derived ACK/NACK feedback in the at least one OFDM symbol and on the at least one subcarrier, based on the first indication of resources for feedback.