Methods and systems are provided for increasing bandwidth efficiency in satellite communications. In some embodiments, a satellite communications method is provided that comprises receiving, at a gateway ground station and as part of a downlink transmission from a satellite, a combined source signal comprising a plurality of source signals with an overlapping bandwidth, and extracting, from the downlink transmission, information specifying at least one predetermined modulation method. The method also includes generating, based on the at least one predetermined modulation method and from the combined source signal, a plurality of estimated waveforms corresponding to the plurality of source signals, separating, by signal cancellation and using the plurality of estimated waveforms, the plurality of source signals from the combined source signal, and routing, with a terrestrial network, the plurality of source signals to one or more user ground terminals.