Low-Complexity Transmit Beamforming for MIMO Systems

This paper proposes a simple downlink transmit beamforming scheme for multiple-input multiple-output systems with low complexity. We first introduce the beamforming system where the base station (BS) utilizes only a fraction of the full channel response. The mobile station (MS) of the proposed system selects a single antenna at the receive side based on which the BS adjusts beamforming weights without any overhead to the structure of the BS. Without requiring the singular value decomposition operation, the proposed scheme achieves a performance very close to that of the optimum beamforming system. An exact analysis of the received signal-to-noise ratio for the proposed scheme with 2 receive antennas is also presented. Simulation results show that with much reduced complexity the performance of the proposed beamforming technique is only a few tenth of a dB away from the optimal beamforming system regardless of antenna configuration.