In some embodiments, a satellite communications network dynamically regulates carrier assignment for bidirectional communications between a satellite and radioterminals. The satellite communications network includes a resource manager that regulates the carrier assignments by selecting among a plurality of FDD return subcarriers, with potentially different subcarrier bandwidths and supporting different radio access technologies, within at least one FDD return carrier grouping for coupling to a selected one of a plurality of FDD forward carriers, and by controlling the satellite network to receive communications from the radioterminal on the selected FDD return subcarrier and to transmit communications to the radioterminal on the selected FDD forward carrier.