Elimination beam-forming in downlink multi-user MIMO systems

Downlink Multi-User MIMO Channel State Information Reference Signal (CSI-RS) transmission scheme is proposed. It is based on an OFDM system and deployment of a large number of antennas at LTE Evolved NodeB transmitter (eNB). The developed scheme efficiently utilizes the transmitted power distribution by the adaptive elimination of the coverage zones where no users are to be served. Hence, more directed CSI-RS beamforming and higher received Signal To Noise and Interference Ratios (SINRs) are achieved for both uniform and clustered user distributions. In addition, Zero Forcing (ZF) beamforming is employed on top of the developed scheme for MU-MIMO data transmissions. Proposed scheme shows significant performance improvement than the conventional standard LTE-A dual codebook while drastically reducing the needed Downlink feedback overhead regardless of the number of physical antennas at eNB.