SINR estimation for power control in systems with transmission beamforming

This paper takes a unified approach to the downlink transmission power control, while a transmission beamforming is applied in the base station. The proposed scheme is based on the estimation of signal-to-interference-and-noise-ratios (SINRs) by antenna array measurement and using this estimate in transmission power control. Hence power control algorithms needing SINR-levels can be applied instead of the simple relay power control. The SINR estimation technique does not require any additional measurements compared to a separate adaptive beamforming and power control, since the required measurements are needed for the adaptive beamforming update. The estimation is based on the knowledge of the level of caused interference to the multiple access links in the same cell, and the utilization of relay power control commands in SINR estimation.