Throughput maximization transmission control scheme using precoding for MIMO systems

Multiple-input multiple-output (MIMO) systems that realize a high-speed data transmission with multiple antennas at both transmitter and receiver are drawing much attention. In MIMO systems, it has been reported that the scheme that weights transmitted signals based on minimum mean square error (MMSE) criterion at the transmitter using feedback channel state information (CSI) achieves good performance (denoted hereafter as MMSE precoding). A throughput maximization transmission control scheme (TMTC) that selects the transmission mode (modulation schemes and code rates) based on CSI has been proposed. We expect that its throughput performance can be improved by addition of MMSE precoding. However, throughput performance is degraded in the presence of feedback delay. In this paper, we propose TMTC with MMSE precoding; it reduces the throughput performance degradation by using channel prediction and the receive weights robust against feedback delay. The proposed scheme selects a transmission mode (the number of substreams, modulation schemes, and code rates) and configures the precoder to achieve maximum throughput based on the SINR given by channel prediction. Simulation results show that even when feedback delay exists, the proposed scheme attains high throughput.