Multi-sector beamforming with MMSE receiver in spatially correlated channel

The use of statistical eigen-beamforming is effective in spatially correlated fading environments, but it may suffer from interference near the sector boundary when applied to the downlink with universal frequency reuse. This interference effect may not sufficiently be handled by a minimum mean square error (MMSE) receiver unless a sufficient number of receive antennas are employed. In this paper, we consider the use of multi-sector beamforming that cooperates with a neighboring sector in the same cell to mitigate this interference problem. By exploiting long-term channel state information (CSI), the proposed scheme can obtain transmit array gain without the use of instantaneous CSI, while avoiding interference from the adjacent cooperating sector. The performance of the proposed scheme is analyzed with combined use of an MMSE receiver and verified by computer simulation.