The described techniques provide for efficiently contending for access to a shared radio frequency spectrum for communicating on multiple allocated sub-bands across multiple carriers. As described herein, a user equipment (UE) may first identify allocated sub-bands across multiple carriers in a shared radio frequency spectrum. The UE may then select a carrier and at least one of the multiple allocated sub-bands within the carrier on which to perform a listen-before-talk (LBT) procedure of a first type, and the UE may perform the LBT procedure of the first type on the at least one sub-band. In addition, the UE may also perform LBT procedures of a second type on allocated sub-bands within carriers different from the selected carrier. Based on the results of the LBT procedures, the UE may communicate with the base station on the allocated sub-bands across the multiple carriers in the shared radio frequency spectrum.