Transmit Beamforming and Iterative Water-Filling Based on SLNR for OFDMA Systems

This paper proposes a transmit beamforming and subcarrier power allocation method for orthogonal frequency division multiple access (OFDMA) systems based on "signal-to-leakage-plus-noise ratio" (SLNR). As the transmit beamforming vector control criterion, we employ the maximization of the SLNR at each base station, while the subcarrier power allocation is performed by iterative water-filling algorithm using the SLNR of each subcarrier. The SLNR based approach enables us to obtain closed form beamforming vector, and achieve power allocation without sending any signal to the mobile terminal. We also discuss the validity of the SLNR based beamforming vector in terms of Pareto optimality. Computer simulations show the promising performance of the proposed method and the validity of the analysis of the SLNR based beamforming vector.