A method and apparatus for managing communications between communications systems is provided. A set of data channels available for use in exchanging data between a communications system and a set of communications systems is identified. A number of constraints for a modulation waveform are identified based on the set of data channels identified and environmental information about a communications environment for the communications between a radio and a set of radios. The modulation waveform that meets the number of constraints is identified. The modulation waveform is configured for use in exchanging the data between the communications system and the set of communications systems over the set of data channels.