US Patent 9706454 Carrier configuration in wireless networks

A base station transmits, to a wireless device, at least one first RRC message comprising configuration parameters of a plurality of cells being grouped into a plurality of cell groups. The base station makes a handover decision for the wireless device. The base station transmits a second RRC message causing in the wireless device, modification of a cell group of a cell without explicitly releasing the cell. The second RRC message comprises mobility control information.