On the analysis of the performance of coded modulation schemes for unequal error protection

A method of analysis for comparing the performance of time-division-coded modulation and superposition-coded modulation schemes with unequal error protection has been proposed. The performance of practical channel codes was modeled heuristically by using a signal-to-noise ratio loss factor λ and it was shown that the superiority of superposition-coded modulation depends on the degree of inequality in protection prescribed. A different approach, using the channel cutoff rate R₀ instead of λ, is proposed here. Results of the analysis of the performance of both approaches are compared, and they are also compared to those results obtained from practical design examples.