Flexible carrier aggregation is provided for a radio communications system. A capability is determined to communicate over a radio interface using multiple radio frequency component carriers. Each of the multiple component carriers is configurable with one or more control channels in a first mode of operation and with no control channels in a second mode of operation. Configuration information for one of the multiple radio frequency component carriers is signaled to indicate at least one of the component carriers is configured to operate in a selected one of the first mode of operation and the second mode of operation so that a network radio node and a user equipment radio node can communicate using the selected mode of operation.