Full-duplex multiuser multiple-input-multiple-output (FD-MU-MIMO) systems are key technologies for the next generation wireless communication systems due to their ability in improving spectral efficiency. The major hurdle of the systems is in suppressing interferences such as the self-interference from downlink to uplink and multiuser interferences in both channels. Thus, it is required to depend on precoding schemes. This paper proposes signal-to-leakage-and-noise ratio (SLNR) precoding for downlink channel and self-interference plus noise covariance matrix aware SLNR precoding for the uplink channel to improve the spectral efficiency of FD mode systems in the Rician fading environment. Unlike zero-forcing and block diagonalization precoding schemes, it has tradeoffs between interference and noise, and again simultaneously support multiple numbers of users and antennas. The problem is formulated as maximizing SLNR to obtain the precoder that optimized the total spectral efficiency of the system. Numerical results confirm that for a given SNR values FD outperforms half duplex as a number of antennas per user in both channels increase, for fixed number of antennas at the base station, for a small power of the self-interference and for all Rician factor.