Performance analysis of zero-forcing-precoded scheduling system with adaptive modulation for multiuser-multiple input multiple output transmission

In this study, the author presents performance analysis of a zero-forcing (ZF)-precoded scheduling system with adaptive modulation for multiuser-multiple input multiple output transmission. The proposed scheduling system adapts the transmission rate and selects the best modulation to satisfy a given target bit error rate (BER). The author derive the tight closed-form expressions of the ZF-precoded system with adaptive modulation for the average spectral efficiency where user set non-scheduling and user set scheduling methods are presented. The author also presents the tight closed-form BER expressions of the non-scheduling and scheduling systems with adaptive modulation for M-ary quadrature amplitude modulation and M-ary phase shift keying modulation. From the analytical results, the author shows that the proposed scheduling system provides performance improvement of the average spectral efficiency over the non-scheduling system. Moreover, the proposed system provides the signal to noise ratio gain compared with the non-scheduling system to satisfy the target BER regardless of modulation types. This is because the diversity order of the proposed system is superior to that of the non-scheduling system by multi-user diversity.