We study the maximization of the weighted sum rate in Gaussian multi-input multi-output OFDM broadcast channel under a total power constraint. This problem is motivated by adaptive resource allocation policies in a multi-carrier wireless system with multiple antennas at the base station. We propose a iterative waterfilling algorithm based on dual decomposition. Two decompositions are considered, one in subcarrier domain and another in both subcarrier and user domain. We show that both

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... ions reduce to an identical problem that can be solved by multiuser waterfilling approach simultaneously for all subcarriers. A master problem is solved iteratively to achieve the total power constraint by a simple bisection method. Numerical examples show that our proposed algorithm converges much faster than steepest ascent algorithm and makes convergence almost independent of a number of subcarriers and antennas.