Methods, systems, and devices for wireless communication are described. A user equipment (UE) or base station communicating in an unlicensed radio frequency spectrum band may transmit a signal (e.g., a request-to-send (RTS) or clear-to-send (CTS) signal) in a licensed radio frequency spectrum band to decrease the likelihood that neighboring devices will transmit interfering communications. Specific resources may be designated in the licensed radio frequency spectrum band for transmitting these signals, and these resources may be associated with specific unlicensed channels. Signaling in the licensed radio frequency spectrum band may also carry an indication of the unlicensed channel being used or other information relevant to the unlicensed communication. The RTS/CTS signaling in licensed radio frequency spectrum band may be transmitted during a downlink transmit opportunity or an uplink transmit opportunity, or both. Different energy detection thresholds may apply to RTS/CTS signals in licensed and unlicensed spectrum.