Apparatus and methods for frequency hopping among a set of frequency channels used for secondary cells by wireless devices operating with carrier aggregation across a combination of licensed and unlicensed radio frequency (RF) bands are described. A wireless device establishes a connection with an eNodeB using a primary component carrier (PCC) of a primary cell in a licensed radio frequency band. The wireless device obtains a configuration for a secondary cell operating in the unlicensed radio frequency band from the eNodeB, the configuration including a set of RF channels and a frequency-hopping pattern for communicating via a secondary component carrier in the secondary cell. The wireless device transmits to or receives from the eNodeB, via the SCC during a first hop of the frequency-hopping pattern using a first frequency channel in the set of frequency channels, and using a second frequency channel during a second hop.