An LCMV-based approach for downlink beamforming in FDD systems in presence of angular spread

An approach based on constrained filtering for downlink beamforming for FDD systems is presented. The impact of the angular spread in the calculation of the beamforming weights is evaluated for such approach, as well as for that based on the maximization of the signal to interference ratio. It is shown that the LCMV-based method leads to an efficient solution with the introduction of eigenvector constraints in the optimization procedure. The simulation results illustrate the good performance of the proposed technique, which presents an acceptable computational complexity and is suitable for adaptive implementation.