An Efficient Algorithm for Zero-Forcing Coordinated Beamforming

The problem of beam tracking for zero-forcing coordinated beamforming in multiple-cell time-varying multiple-input multiple-output channels is considered. Based on null-space perturbation theory, an efficient update algorithm for block-diagonalization-based zero-forcing coordinated beam design is proposed and its performance is analyzed. In slowly-varying channels, the proposed algorithm well tracks the zero-forcing beam solution and significantly reduces computational complexity by simply updating beamforming matrices instead of redesigning them with new channel state information at each time step.