Optimal independent-encoding schemes for input-symmetric degraded broadcast channels

An input-symmetric (IS) degraded broadcast channel (DBC) is a discrete DBC whose component channels are input-symmetric and the intersection of their input-symmetry groups is transitive. The discrete additive DBC and the group-additive DBC are IS-DBCs. This paper introduces an independent encoding scheme which employs permutation functions of the independent codes. This permutation encoding approach for the group-additive DBC is to employ group additions of the independent codes. This paper shows that the permutation encoding approach achieves the boundary of the capacity region for IS-DBCs, and yields a simple characterization of that capacity region.