Spatial Characteristics of Distortion Radiated from Antenna Arrays with Transceiver Nonlinearities
Journal article, 2018

The distortion from massive MIMO (multiple-input--multiple-output) base stations with nonlinear amplifiers is studied and its radiation pattern is derived. The distortion is analyzed both in-band and out-of-band. By using an orthogonal Hermite representation of the amplified signal, the spatial cross-correlation matrix of the nonlinear distortion is obtained. It shows that, if the input signal to the amplifiers has a dominant beam, the distortion is beamformed in the same way as that beam. When there are multiple beams without any one being dominant, it is shown that the distortion is practically isotropic. The derived theory is useful to predict how the nonlinear distortion will behave, to analyze the out-of-band radiation, to do reciprocity calibration, and to schedule users in the frequency plane to minimize the effect of in-band distortion.

out-of-band radiation

in-band distortion

massive multiple-input multiple-output



spectral regrowth


reciprocity calibration


Christopher Mollen

Linköping University

Ulf Gustavsson


Thomas Eriksson

Chalmers, Electrical Engineering, Communication and Antenna Systems, Communication Systems

E. G. Larsson

Linköping University

IEEE Transactions on Wireless Communications

1536-1276 (ISSN)

Vol. 17 10 6663-6679 8429913

Areas of Advance

Information and Communication Technology

Subject Categories


Signal Processing



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