Robust multicast beamforming using covariance channel state information

The problem of transmit beamforming design for multicast wireless system is considered in this paper. We focus on the robust long-term transmit beamforming design with only imperfect knowledge of the channel covariance from two view points: minimizing total transmission power with prescribed signal-to-noise ratio (SNR) constraints at the receivers and maximizing the minimum SNR to achieve the relative max-min fairness. Only infrequent feedback is required from the users in such an algorithm. Furthermore, the algorithm shows great tolerance of imperfect channel state information (CSI) on both transceiver sides. It is shown that we can formulate both of the optimizations as convex semidefinite programming (SDP) problems by applying semidefinite relaxation (SDR) techniques. Extensive simulation results are presented to corroborate the performance of our proposed design.