A Feedback Scheme for ZFBF-Based MIMO Broadcast Systems with Infrastructure Relay Stations

Zero-forcing beamforming (ZFBF) is a promising technique for multiuser MIMO systems. However, such method requires all the users to feed their channel information back to the base station (BS), so the BS can select the users and receive antennas as well as computing the transmit beamforming matrix. The quality of feedback information is crucial to the resultant system throughput. In order to reduce the power expenditure of the mobile stations (MS) while preserving the feedback quality, we propose a new feedback scheme based on the use of infrastructure relay stations (RS). The simulation results show that the scheme generally gives a better average throughput with lower SNR value requirements.