A satellite communications system comprises a transmitter, a satellite transponder and a receiver. The transmitter transmits an uplink multi-level modulated signal (hierarchical modulation or layered modulation) to the satellite transponder, which broadcasts the multi-level modulated signal downlink...http://www.google.com.au/patents/US7616706?utm_source=gb-gplus-sharePatent US7616706 - Repetition coding in a satellite-based communications system
