Indoor experiment of 8-by-2 multiuser MIMO transmission using Tomlinson-Harashima-Precoding subject to limited CSI feedback

This paper presents indoor experimental results of 8-by-2 multiuser MIMO (MU-MIMO) transmission using Tomlinson-Harashima-Precoding (THP) subject to limited Channel State Information (CSI) feedback. The channel correlation in indoor environment tends to be high because user equipments for MU-MIMO are situated close to each other due to the limited space. In such environment, MU-MIMO using linear precoding degrades the spectrum efficiency. The merit of this work is to experimentally confirm the feasibility of THP, which is robust to highly correlated channel, subject to limited CSI feedback. Experimental results reveal that the THP does not degrade under the highly correlated environment and the peak spectrum efficiency reaches 17 bit/sec/Hz.