Unequal Power Amplifier Dimensioning for Adaptive Massive MIMO Base Stations

In this paper, we propose a novel power amplifier (PA) dimensioning method for massive multiple-input multiple-output (MIMO) systems whose number of transmitting antennas is adapted according to the number of user equipments (UEs) in the cell. The dimensioning method sets the maximum output powers of PAs unequally according to the pre-calculated average per-antenna transmission powers for different number of UEs. This allows PAs to operate at higher efficiency when the average per-antenna transmission powers vary due to the adaptive number of transmitting antennas. The performance of the method is evaluated in the symmetric multi-cellular scenario using a comprehensive power consumption model that considers both base station and UEs. When simple class-B PAs are used at the base station, unequal PA dimensioning reduces the PA power consumption up to 42 % when compared to the conventional equal PA dimensioning. This improves the total system energy efficiency. The benefits of the proposed unequal PA dimensioning are that no prior knowledge of the UE distribution is needed and good performance is achieved for all UE densities.

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