Speaker:  Ishhanie Majumdar   ee12s058

ABSTRACT :

Multi-user MIMO (MU-MIMO) technology has gained considerable application due tothe fact that it can greatly increase the information capacity of wireless communicationsystems. However, there is a phenomenon which has a limiting effect on MU-MIMO broadcast transmissions besides various other physical limitations, known as multi-user interference (MUI) which is our problem of interest. There are techniques to mitigate MUI known as precoding which are employed typically at the transmit side. A study of a class of linear precoding algorithms known as block diagonalization (BD) type precoding algorithms is performed. The mathematical details of these algorithms are presented in this thesis. We have implemented these algorithms in a OFDM based  framework complying with WLAN standard IEEE 802.11ac. The investigation of these

algorithms include comparison and analysis of their BER performance and achievable  sum-rate for 160 MHz IEEE 802.11ac channel.

IEEE 802.11ac provides beamforming technique known as null data packet (NDP)

beamforming. This beamforming standard includes a feedback mechanism known as  compressed beamforming matrix feedback. We have performed a mathematical analysis  of a MU-MIMO system with one of the precoding algorithms considered in this work along with the aforementioned feedback mechanism. The implementation of this feedback mechanism in ourMIMO-OFDMframework includes the aforesaid precoding  algorithm. We observe that the system with compressed beamforming matrix feedback  works as good as perfect feedback.