Fourier Analysis of MAC Polarization

A problem of the polar code construction for multiple access channels (MACs) is that they do not always achieve the whole capacity region. Although polar codes achieve the sum-capacity of symmetric MACs, polarization may induce a loss in the capacity region which prevents polar codes from achieving the whole capacity region. This paper provides a single letter necessary and sufficient condition which characterizes all the MACs that do not lose any part of their capacity region by polarization.

Related material