Effect of Imperfect Transmit Correlation on Statistical Beamforming in Multi-User Cellular Systems

This letter investigates the effect of imperfect transmit correlation on the performance of statistical beamforming in terms of average signal-to-interference plus noise ratio (SINR) in a correlated multi-user multi-antenna cellular system. The average SINR of the statistical beamforming depends on the accuracy of transmit correlation information as well as the characteristics of co-channel interference (CCI) from adjacent base stations. It is shown by means of multivariate Taylor series expansion that the average SINR degradation due to imperfect transmit correlation is associated with the mean squared error (MSE) and the number of quantization bits, and that those effect significantly varies depending on the correlation magnitude and the phase difference between the transmit correlation coefficient of the intended and CCI channel.