Apparatus and method for superposition transmissions

An apparatus for selecting a superposition constellation comprising two or more user equipment (UE) constellations, comprising:

• at least one non-transitory computer-readable medium storing instructions capable of execution by a processor;
• and
• at least one processor capable of executing instructions stored on the at least one non-transitory computer-readable medium, where the execution of the instructions results in the apparatus performing a method comprising:
• determining which type of superposition constellation (super-constellation) to generate based at least on a power ratio among the two or more UEs, wherein one type of super-constellation is a Gray-mapped Non-uniform-capable Constellation (GNC), in which both the constituent constellations of the two or more UEs and the GNC super-constellation itself are Gray-mapped;
• and
• when the determined type of superposition constellation is the GNC super-constellation, generating the determined type of superposition constellation by mapping the GNC super-constellation from outermost bits to innermost bits according to each of K number of UEs.