Impact of Spatial Filtering on Distortion from Low-Noise Amplifiers in Massive MIMO Base Stations
Journal article, 2018

Because of the large number of antennas at the base station, the power consumption and cost of the low-noise amplifiers (LNAs) can be substantial. Therefore, we investigate the feasibility of inexpensive, power efficient LNAs, which inherently are less linear. To characterize the nonlinear distortion, the LNAs are described using a polynomial model, which allows for the derivation of the second-order statistics of the distortion. We show that some terms of the distortion from the LNAs combine coherently, and that the SINR of the symbol estimates therefore is limited by the linearity of the LNAs. Furthermore, the impact of a strong transmitter in the adjacent frequency band is investigated. The second-order statistics show how the power from that transmission leaks into the main band and interferes with the symbol estimates. The term that scales with the cube of the power received from the blocker can be filtered out by spatial processing. Only the coherent term that scales with the square of the power remains. Nonlinear distortion from the LNAs can be reduced by spatial processing in massive MIMO. However, it does not vanish as the number of antennas is increased.

Nonlinear distortion

Base stations

nonlinear distortion


MIMO communication



antenna arrays


MIMO systems



Christopher Mollen

Linköping University

Ulf Gustavsson


Thomas Eriksson

Chalmers, Electrical Engineering, Communication, Antennas and Optical Networks

Erik G. Larsson

Linköping University

IEEE Transactions on Communications

00906778 (ISSN) 15580857 (eISSN)

Vol. 66 12 6050-6067 8398419

Areas of Advance

Information and Communication Technology

Subject Categories


Communication Systems

Signal Processing



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