SINR-Max cooperative beamforming for multiuser MIMO-OFDM systems

In our previous works, we proposed an uplink transmit beamforming design algorithm for multiuser multiple-input multiple-output (MIMO) systems in frequency non-selective channels, under the assumption that cooperation exists among multiple users so that the full multiuser channel state information (FMCSI), i.e. the collection of the channel state information between each of the users and the base station, is available at each of the multiple users. The proposed algorithm, aiming to maximize the signal to multiuser interference plus noise ratio (SINR), is referred to as SINR-Max cooperative beamforming. In this paper, we extend the application of SINR-Max cooperative beamforming to frequency selective block invariant channels by combining orthogonal frequency division multiplexing technique into MIMO systems (MIMO-OFDM). We designed two alternative transmitter structures with pre-IDFT beamforming in the frequency domain and post-IDFT beamforming in the time domain respectively, and the receiver structure common to both types of transmitters. For post-IDFT transmitter, we investigated different implementation options. Performance of the designed systems with different schemes is evaluated and compared through simulations.