Method and apparatus for maintaining independent, parallel data streams over separate modulation channels of a multi-dimensional modulator

A method and apparatus are provided for supporting the transmission of communications data in a satellite communications network between user terminals and a ground station via a satellite . At least one carrier signal is generated in a beam spot and conveys communications data over at least one downlink to the user terminals . The carrier signal is modulated simultaneously with independent communications data streams EDP and EDP over modulation channels and , respectively, of a multi-dimensional modulator . By passing independent data streams over each dimension of an n-dimension modulation technique, different encoding schemes may be assigned to user terminals based upon the strength of the signal received by the user terminal