CTH01-2: Optimum Ergodic Power Allocation for Multiuser OFDM with Arbitrary Signal Constellations

This paper formulates the power allocation policy that maximizes the region of ergodic mutual informations achievable in multiuser downlink OFDM channels known only statistically by the base station. Arbitrary partitioning of the available tones among users and arbitrary modulation formats, possibly different for every user, are considered. The derivation relies on the nexus between the mutual information of Gaussian channels and the minimum mean-square error incurred in the nonlinear estimation of the transmit constellation points given their noisy receive observations.