Balanced beamforming for decode-and-forward based MISO relay communications

This paper proposes a beamforming technique for multiple-input single-output (MISO) decode-and-forward (DF) based relay communications. The proposed beamformer is constructed by linearly combining two independently designed beamformers that maximize data rates at relay and destination, respectively. Contrary to conventional beamforming in DF relay communications, the proposed beamformer balances direct and relay links and maximize the achievable rate of the overall system. It is shown that the proposed beamforming scheme achieves significantly higher data rates than conventional beamforming neglecting a direct link.