Systems, methods, and instrumentalities may be disclosed for implementing a flexible radio access communication system. A flexible radio access communication system may be supported using spectrum of varying size, including aggregation of non-adjacent carriers in the same and/or in different frequency bands. A wireless transmit/receive unit (WTRU) may receive a first transmission via a common downlink control channel. The first transmission may include first control information. The first control information may include information regarding the configuration of a first dedicated downlink control channel of one or more dedicated control channels. The WTRU may receive a second transmission via the first dedicated downlink control channel of the dedicated control channels. The second transmission may include second control information. The second control information may be associated with a transmission of a first transmission type. The dedicated downlink control channels may be used for providing control information associated with different types of transmissions.