Optimal ZF Precoder Under per Antenna Power with Conjugate Beamforming for MU Massive MIMO Systems
In this paper, we deliberate on multiuser massive multiple-input multiple-output (MU-MIMO) system in designing optimal zero forcing (ZF) precoder under per antenna power constraint. MU massive MIMO with non-square matrix is restrained by the large channel matrix dimension, conjugate beamforming maximization approach is developed to align the channel matrix for the optimal ZF precoder. We further introduced complex lattice reduction (CLR) to transform the lattice bases of the channel matrix and shorten the basis vector, thus meliorates the orthogonality of the conjugate beamforming. Simulation results show LR-based optimal ZF precoder outperforms other precoding schemas. The LR-based optimal ZF precoder improved the beamforming for the base station (BS) to focus on the users, thus improving spatial multiplexing gain and diversity order. As BS antennas and users turn large, the sum rate over the subchannels depends on the dominance of users (that is BS antennas to user antennas ratio) for the channel gain. Thus performance of the LR-based precoder schema under per antenna power can help save power in practical massive MIMO implementation.
KeywordsMU massive MIMO Zero forcing (ZF) precoder Conjugate beamforming Lattice reduction (LR) Per antenna power
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