Hierarchical Modulation Efficiency (ME): Normalized Effective Signal to Noise Ratio

By normalizing effective signal-to-noise ratio (ESNR) with γ, we can obtain hierarchical modulation efficiency (ME) η by

η (γ) = ˜γ γ = 1 γΨ−1 (pe(γ)) . (12)

With no interference, η (γ) = 1; otherwise, η (γ) < 1. η is also the measure of inter-layer resistance for hierarchical modulation. The high ME value means stronger interference resistance the modulated signal has.