Optimal transmit pre-coding and channel capacity of multiple antenna systems

Abstract

Multiple input multiple output (MIMO) systems using multiple transmit and receive antennas are widely recognized as a vital breakthrough for future wireless systems to achieve higher data rates on a bandlimited fading channel. To achieve the channel capacity, we need to optimize the transmitter which, in turn, is dependent on feedback information available at the transmitter, the correlation among transmit and receive antennas, and other channel conditions. This thesis presents the results we obtained on transmitter optimization for MIMO systems with different channel conditions. The thesis contains four main results. First, for a single-user multiple input single output(MISO) channel with perfect channel knowledge at the receiver and the knowledge of only the channel statistic information at the transmitter, we characterize the optimal input strategy, by which the channel capacity can be achieved. Second, for a single-user MIMO channel with only statistic information feedback, we propose the best transmit scheme and develop two simplified power allocation algorithms. Third, we show that with mutual coupling at both the transmitter and the receiver, we need to take the effect of mutual coupling into consideration. We demonstrate how the mutual coupling influences the optimal transmit strategy analytically. Fourth, for a multiuser MIMO broadcast channel (BC), we discuss the optimal transmit scheme and channel capacity. We show that the method used in finding the optimal transmit scheme for single-user MIMO system can be applied in MIMO BC by an iterative algorithm.