  This work investigates interference mitigation techniques in multi-user
multiple input multiple output (MU-MIMO) Intelligent Reflecting Surface
(IRS)-aided networks, focusing on the base station end. Two methods of precoder
design based on block diagonalization are proposed. The first method does not
consider the interference caused by the IRS, seeking to mitigate only the
multi-user interference. The second method mitigates both the IRS-caused
interference and the multi-user interference. A comparison between both methods
within an no-IRS MU-MIMO network with strong direct links is provided. The
results show that, although in some circumstances IRS interference can be
neglected, treating it can improve system capacity and provide higher spectral
efficiency
