A first base station receives, from a second base station, cell configuration parameters of one or more cells of the second base station. The cell configuration parameters indicate: at least one first information element (IE) indicating a first identifier of a first cell of the one or more cells; at least one second IE indicating that the first cell is an unlicensed cell; and at least one third IE indicating one or more configuration parameters of radio resources of the unlicensed cell. The first base station sends, to the second base station, a handover request message for a wireless device based on the cell configuration parameters.