Chip-Level Coordinated Interference-Aware Beamforming for MIMO-CDMA in Frequency-Selective Broadcast Channels

In this paper a linear multi-user beamforming technique is proposed for frequency-selective channels in multiple-input-multiple-output (MIMO) wideband code division multiple access (WCDMA) system. Assuming perfect Channel State Information (CSI) is available at both transmitter and receiver, transmit beamforming and receive beamforming are coordinated to mitigate multi-user, multiple access (MAI), and Inter-Chip Interference (ICI) by maximizing an approximate lower bound of each individual signal to interference and noise ratio (SINR). Chip-level equalization is selected to mitigate the ICI due to its low computational complexity. Simulation results indicate that this technique outperforms traditional linear techniques in approaching high receive SINR, thus achieving higher data rates and/or lower error rates in large interference cases.