Practical Costa precoding for the multiple antenna broadcast channel

For a multiple antenna broadcast channel, the sum-rate capacity achieving transmit strategy requires the centralized transmitter to simultaneously communicate with multiple receivers. The objective of this paper is to design an implementable sum-rate capacity achieving transmit strategy that uses a combination of beamforming and coding for known interference. For a Gaussian broadcast channel with two transmit antennas and two receivers with one antenna each, results indicate that with QAM constellations there is significant gain in sum-rate capacity over an approach that uses only beamforming.