Weighted sum rate maximization for hybrid beamforming design in multi-cell massive MIMO OFDM systems

Kurisummoottil Thomas, Christo; Slock, Dirk TM
EUSIPCO 2019, 27th European Signal Processing Conference, 2-6 September 2019, Coruna, Spain

This work deals with hybrid beamforming (HBF) for the MIMO Interfering Broadcast Channel (IBC), i.e. the Multi-Input Multi-Output (MIMO) Multi-User (MU) Multi-Cell
downlink channel, in an orthogonal frequency-division multiplexing (OFDM) system. While most of the existing works on wideband hybrid systems focus on single-user systems and a few on multi-user single-cell systems, we consider HBF design
for OFDM systems in the case of multi-cell. We optimize the weighted sum rate (WSR) using minorization and alternating optimization, the result of which is observed to converge fast to a local optimum. We furthermore propose a deterministic annealing based approach to avoid issues of local optima that plague phase shifter constrained analog beamformers. Simulation results indicate that the proposed deterministic annealing based
approach performs significantly better than state of the art Weighted Sum Mean Squared Error (WSMSE) or WSR based solutions in a wideband OFDM setting. We also propose a closed form solution for the frequency flat analog BF in case the number of RF chains equals or exceeds the total number of multipath components and the antenna array responses are phasors.

Systèmes de Communication
Eurecom Ref:
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