Noniterative Coordinated Beamforming for Multiuser MIMO Systems With Limited Feedforward

This letter proposes three methods to jointly calculate beamforming and combining vectors for the downlink of TDD multiuser multiple-input multiple-output systems. The algorithms use quantized information of the beamformers to get the corresponding combiners, maximizing the signal-to-interference-plus-noise-ratio. Two of the proposed methods exceed in performance those already published. The third method reduces the feedforward overhead with a light degradation in performance. Our three proposals are based on a perfect interference cancellation at the transmitter before calculating the quantized beamformers.