Non-conservative robust joint transmission beamforming for multicell multiuser systems

This paper studies robust beamforming design for the downlink multicell multiuser joint transmission systems in the presence of channel state information (CSI) error at the base stations (BSs). We address the problem of maximizing the minimum worst-case signal-interference-noise ratio (max-min worst-case SINR) subject to per-BS power constraints. Unlike the conservative robust beamforming algorithm design, the max-min worst-case SINR problem is solved through solving a series of transmit power minimization problems subject to per-user worst-case SINR constraints and per-BS power constraints where the per-user worst-case SINR constraints are transformed into an optimization problem with some additional auxiliary variables. Numerical results demonstrate that the proposed scheme obtained a better performance than the conservative scheme in terms of the average worst user rate.