Enhancing performance of block diagonalization precoding in multi user MIMO (MU-MIMO) downlink

Rapid development of Broadband Wireless Access (BWA) requires improvement of system capacity. MU-MIMO is considered as a benefit solution as its ability to enhance the system capacity without additional bandwidth. However, the implementation of MU-MIMO creates interference problem that is Multi User Interference (MUI). Thus in order to suppress the MUI, precoding technique is needed before the signal is transmitted. Linear precoding is suitable to be implemented due to its low complexity yet it has lower capacity than non-linear. One of linear precoding methods is Block Diagonalization (BD) which has flexible configurations so, the capacity can be increased. In purpose to obtain performance enhancement of BD, this study focuses on improving performance and finding the best configuration of BD for BER performance. The research accomplished by analyzing the effect of the change of numbers between transmitting and receiving antenna; and analyzing performance of BD towards different channel response. The result of this research is the performance improvement of BD is in line with adding the number of received antennas on user and reducing the number of transmitting antennas. In addition, better performance can be achieved by implementing BD in lower LOS factor. Therefore, performance of BD in i.i.d Rayleigh is better than Rician channel. By using BD {1,1}×2 configuration, the best performance of BD can be achieved.