TY - GEN
T1 - New beamforming schemes with optimum receive combining for multiuser MIMO systems
AU - Lee, Sang Rim
AU - Park, Seokhwan
AU - Moon, Sung Hyun
AU - Lee, Inkyu
PY - 2008
Y1 - 2008
N2 - In this paper, we present a new beamforming scheme for a downlink of multiuser multiple-input multiple-output (MIMO) communication systems. Recently, a block-diagonalization (BD) algorithm has been proposed for the multiuser MIMO downlink where both a base station and each user have multiple antennas. However, the BD algorithm is not efficient when the number of supported streams per user is smaller than that of receive antennas. Since the BD method utilizes the nullspace based on the channel matrix without considering the receive combining, the degree of freedom for beamforming cannot be fully exploited at the transmitter. In this paper, we optimize the receive beamforming vector under a zero forcing (ZF) constraint, where all inter-user interference is driven to zero. We propose an efficient algorithm to find the optimum receive vector by an iterative procedure. The proposed algorithm requires two phase values feedforward information for the receive combining vector. Also, we present another algorithm which needs only one phase value by using a decomposition of the complex general unitary matrix. Simulation results show that the proposed beamforming scheme outperforms the conventional BD algorithm in terms of error probability and obtains the diversity enhancement by utilizing the degree of freedom at the base station.
AB - In this paper, we present a new beamforming scheme for a downlink of multiuser multiple-input multiple-output (MIMO) communication systems. Recently, a block-diagonalization (BD) algorithm has been proposed for the multiuser MIMO downlink where both a base station and each user have multiple antennas. However, the BD algorithm is not efficient when the number of supported streams per user is smaller than that of receive antennas. Since the BD method utilizes the nullspace based on the channel matrix without considering the receive combining, the degree of freedom for beamforming cannot be fully exploited at the transmitter. In this paper, we optimize the receive beamforming vector under a zero forcing (ZF) constraint, where all inter-user interference is driven to zero. We propose an efficient algorithm to find the optimum receive vector by an iterative procedure. The proposed algorithm requires two phase values feedforward information for the receive combining vector. Also, we present another algorithm which needs only one phase value by using a decomposition of the complex general unitary matrix. Simulation results show that the proposed beamforming scheme outperforms the conventional BD algorithm in terms of error probability and obtains the diversity enhancement by utilizing the degree of freedom at the base station.
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U2 - 10.1109/ICC.2008.773
DO - 10.1109/ICC.2008.773
M3 - Conference contribution
AN - SCOPUS:51249097442
SN - 9781424420742
T3 - IEEE International Conference on Communications
SP - 4118
EP - 4122
BT - ICC 2008 - IEEE International Conference on Communications, Proceedings
T2 - IEEE International Conference on Communications, ICC 2008
Y2 - 19 May 2008 through 23 May 2008
ER -