Determination of MIMO Channel Capacity and Enhancement of MIMO System Performance Using Tomlinson Harashima Precoding

Multiple input multiple output (MIMO) systems using multiple transmit and receive antennas are widely recognized as the vital breakthrough that will allow future wireless systems to achieve higher data rates with limited bandwidth and power resources. The capacity of MIMO systems depends strongly on whether the channel state information (CSI) is available at the transmitter or not. The main aim of this paper is to carry out investigations of MIMO system capacity under different assumptions about the underlying channel. The analysis of MIMO channel capacity has been carried out for two different cases based on the quality of channel state information at the transmitter side assuming that the receiver has full channel information. When the CSI is known to transmitter, the MIMO channel capacity has been determined using waterfilling algorithm. Also, analysis over the capacity of the MIMO channel systems has been considered when CSI is considered imperfect at the transmitter. In this paper we will also study about precoding techniques used to enhance the performance of MIMO system. By precoding we mean all methods applied at the transmitter that facilitates detection at the receiver. Precoding has been used in single user (SU) MIMO to improve the SNR at the receiver. In multiuser (MU) MIMO systems precoding is essential to eliminate or minimize Multiuser Interference (MUI). 