A wireless transmit/receive unit (WTRU) may receive configuration information indicating a first and a second cell group, and indicating discontinuous reception (DRX) information for them; and may receive a command associated with DRX. The WTRU may perform, based on the command, DRX for cells of the first and second cell groups. A first active time for the first cell group may differ from a second active time for the second cell group. Cells within the first cell group may be active during the first active time; cells within the second cell group may be active during the second. The WTRU may receive a first command to deactivate a first cell of the first cell group, and deactivate the cell based on the first command. The WTRU may receive a first command to reactivate the deactivated first cell, and reactivate the deactivated first cell based on the first command to reactivate.