Superposition Modulation/Mapping (SM) is a newly
evolving modulation technique in which the conversion from
binary digits to symbols is done by linear superposition of the
binary digits instead of bijective (one-to-one) mapping. Due
to linear superposition, the symbol distribution of the data
symbols thus formed are Gaussian shaped which is capacity
achieving without active signal shaping. In this paper, a detailed
study on SM has been presented with respect to its different
power allocation schemes namely Equal Power Allocation
(EPA), Unequal Power Allocation (UPA) and Grouped Power
Allocation (GPA). Also, it has been shown that SM is more
capacity achieving than the conventional modulation
technique such as Quadrature Amplitude Modulation (QAM)