  In multiple input multiple output (MIMO) systems, precoding allows the base
station to spatially focus and multiplex signals towards each user. However,
distortion introduced by power amplifier nonlinearities coherently combines in
the same spatial directions when using a conventional precoder such as maximum
ratio transmission (MRT). This can strongly limit the user performance and
moreover create unauthorized out-of-band (OOB) emissions. In order to overcome
this problem, the zero third-order distortion (Z3RO) precoder was recently
introduced. This precoder constraints the third-order distortion at the user
location to be zero. In this work, the performance of the Z3RO precoder is
validated based on real-world channel measurement data. The results illustrate
the reduction in distortion power at the UE locations: an average distortion
reduction of 6.03 dB in the worst-case single-user scenario and 3.54 dB in the
2-user case at a back-off rate of -3 dB.
