An Application of Time Division Multiplexing on Multi-User MIMO THP Systems in the Presence of High Mobility Terminals

Multi-user MIMO (MU-MIMO) employing Tomlinson Harashima Precoding (THP) is a powerful technique to enhance the system capacity in multi-user mobile communications systems. However, MU-MIMO has an inherent drawback in the degradation of the transmission performance due to the time variant fading channels which are caused by the mobility of the mobile station (MS). Considering that MU-MIMO is mainly applied to mobile communications systems, the performance degradation due to this terminal mobility has to be solved. This paper proposes a novel MU-MIMO THP transmission scheme for the sake of alleviating the performance degradation due to the terminal mobility. The feature of the proposed approach is to incorporate the concept of time division multiplexing (TDM) into MU-MIMO THP system, which enables the transmission of high mobility user to take precedence over that of the lower mobility user. Thanks to the use of TDM, the proposed scheme exploits the space diversity benefit because TDM decreases the number of MSs within a time slot. The effectiveness of the proposed scheme is demonstrated in comparison with the traditional MU-MIMO THP scheme by means of computer simulations.