Decentralized sum MSE minimization for coordinated multi-point transmission

Two decentralized minimum mean-squared error downlink beamformer designs are proposed for multiple-input single-output coherent coordinated multi-point transmission. We propose a parallel beamformer design with a fast initial rate of convergence for systems with relatively few cooperative base stations (BSs). An alternating direction method of multipliers based design is provided for more complex systems with a large number of cooperating BSs. Support for data sharing among the serving BSs is assumed over limited back-haul connectivity. Channel state information (CSI) is not shared among the cooperating transmitters, and, thus, only local CSI is available at each BS via uplink pilot signaling.