Systems and methods for efficient use of unlicensed spectrum are disclosed. In some embodiments, a method performed by a transmitter comprises performing a Listen-Before-Talk (LBT) procedure for a channels within a transmit bandwidth of the transmit node, where the transmit bandwidth is divided into a bandwidth parts that correspond to the channels. The method further comprises transmitting a transmission in a subset of the bandwidth parts that correspond to a subset of the channels determined, based on a result of the LBT procedure, to be available. Transmitting the transmission comprises transmitting the transmission in accordance with a transmit scheme that uses carrier aggregation and/or carrier merging to transmit the transmission on the subset of the bandwidth parts and uses resources in one or more guard bands between two or more adjacent bandwidth parts from among the subset of the bandwidth parts.