  A tradeoff between sum rate and fairness for MISO broadcast communication
employing dirty paper coding or zero-forcing dirty paper coding at physical
layer is investigated in this paper. The tradeoff is based on a new design
objective termed "tri-stage" approach as well as a new L1-based fairness
measure that is much more robust than the well-known Jain's index for comparing
fairness levels achieved by various design objectives at a much finer
resolution in high SNR regime. The newly proposed tri-stage design also
introduces a new concept of statistical power allocation that randomly
allocates powers to users based on an optimal probability distribution derived
from the tradeoff between sum rate and fairness. Simulation results show that
the proposed approach can simultaneously achieve a larger sum rate and better
fairness than the reputable proportional fairness criterion. A performance
upper bound is also given in the paper to show that the excellent performance
of the proposed approach at moderate and high SNR regimes as well as some
potential for further improvement in low SNR regime.
