Apparatus and methods for time division multiplexing of radio frequency channels in unlicensed radio frequency bands by a wireless device in communication with a cellular wireless network are disclosed. The wireless device obtains, from an eNodeB, a configuration for carrier aggregation using a primary component carrier (PCC) in a licensed radio frequency band and at least one secondary component carrier (SCC) in an unlicensed radio frequency band. The configuration information specifies an “on” time period and an “off” time period for a repetitive time division cycle to use the at least one SCC in the unlicensed radio frequency band. During an “on” time period, the wireless device can transmit or receive using the PCC and the at least one SCC, as scheduled by the eNodeB. During an “off” time period, the wireless device can transmit or receive using the PCC and not using the at least one SCC.