In this study, we propose several power allocation schemes in a coordinated base station downlink transmission
with per antenna and per base station power constraints. Block Diagonalization is employed to remove
interference among users. For each set of power constraints, two schemes based on the waterfilling distribution
are proposed and compared to the optimal solution, which can only be obtained numerically by using convex
optimization. We show that the proposed schemes achieve a performance, in terms of weighted sum rate, very
close to the optimal, without the heavy computational complexity required by the latter. The sum rates are
compared first in a simplified two-user two-cell case where we also compare our approach to the previous
solutions available in the literature. Then, we examine the performance in a multi-cell scenario where we also
evaluate the degradation of the performance caused by imperfect channel state informationThis study has been partly funded by projects TEC2008-06327-C03-02,
CCG10-UC3M/TIC-4620, and CSD2008-00010.Publicad