Performance improvement of multi-user MIMO system in the presence of nonlinear distortion

In the presence of nonlinear distortion, the performance degradation of multiuser multiple-input multiple-output (MU-MIMO) systems becomes significant. The performance loss comes not only from the in-band nonlinear distortion, but also from the imperfect cancellation of multiuser interference (MUI) due to the nonlinear distortion. In this regard, we analyze characteristics of nonlinear distortion in an MU-MIMO system. Numerical results show that even tiny nonlinear distortion severely degrades the performance of MU-MIMO system. A nonlinear minimum mean square error (NMMSE) detection algorithm is proposed to improve the system performance. The proposed detection algorithm improves the system performance at low additional cost.