A method for supporting Hybrid Automatic Repeat Request (HARQ) transmission during component carrier (CC) reallocation. The method includes starting a HARQ process using a first CC, allocating a second CC, mapping the HARQ process from the first CC to the second CC, and transmitting remaining HARQ data associated with the HARQ process using the second CC. Also included is a method for supporting HARQ transmission during CC reallocation comprising starting a HARQ process using a first CC, determining to allocate a second CC, waiting until completion of the HARQ process using the first CC before allocating the second CC, and beginning another HARQ process on the second CC. Included is a method comprising starting a HARQ process using a first CC, allocating a second CC, discontinuing transmission using the first CC before completion of the HARQ process, and restarting new data using the second CC.