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| A Random Multi-beam Multiplexing Technique for the Downlink of Multiuser MIMO System |
| Huang Yong-ming; Xu Dao-feng; Yang Lu-xi |
| Department of Radio Engineering, Southeast Univ., Nanjing 210096, China |
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Abstract A novel random multi-beam multiplexing technique is proposed in this paper, which improves the system throughput by exploiting both multiuser diversity and spatial freedom degrees of multiple transmit antennas at the base station. Different from conventional random beamforming techniques, the proposed one first randomly selects one codeword from a given codebook of precoding matrices, then schedules several spatially multiplexing users and determines other precoding matrices. A successive scheduling algorithm is proposed, which selects a main transmit user and determines the secondary precoding matrix for the other user in the first training phase, then the secondary transmit user is selected based on the secondary precoding matrix in the second training phase. This successive scheduling way is capable of fully suppress the mutual interference between multiplexing users at cost of little feedback overhead. Also, the proposed technique can be extended to heterogeneous cases where users may be configured with different number of receive antennas. Simulation results demonstrate that the proposed technique achieves good throughput over different correlated channel environments.
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Received: 28 July 2006
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2008, Vol. 30 
