A system for, and method of, determining channel throughput achievable under superposition coding given a finite, predetermined set of allowed transmission rates and a related system for, and method of, maximizing channel throughput. In one embodiment, the system includes: (1) a noise level calculator configured to calculate associated optimal noise levels for at least some rate subsets of the set of allowed transmission rates and (2) a code feasibility calculator associated with the noise level calculator and configured to determine whether feasible superposition codes exist for the at least some rate subsets given the associated optimal noise levels and thereby identify ones of the at least some rate subsets that are suitable for subsequent wireless transmissions.