Methods, systems, and devices for wireless communication are described. A wireless device may determine whether a source carrier for an uplink grant is in licensed or unlicensed spectrum and then select a listen-before-talk (LBT) procedure for accessing a shared spectrum channel. For example, the device may select one range parameter (e.g., q value) for a backoff procedure of a clear channel assessment (CCA) if the source carrier is in unlicensed spectrum, and a different (e.g., larger) range parameter if the source carrier is in licensed spectrum. In some cases, the device may operate in a stand-alone operating mode and the source carrier may be identified based on the mode. In some cases, the device may receive signaling that indicates a carrier configuration, and may select the LBT procedure based on whether a carrier configured on unlicensed spectrum is self-scheduled or cross-carrier scheduled.