Outage Constrained Robust Transmit Beamforming for Limited Feedback Multiuser MIMO Downlinks

This work studies the design of robust transmit beamforming under receiver outage constraint for limited feedback multiuser multiple-input multiple-output (MIMO) downlinks. We propose a new stochastic model to characterize the channel uncertainty resulting from vector quantization-based limited feedback schemes. With this uncertainty model, we develop two convex optimization formulations to minimize the transmitted power subject to per user quality of service (QoS) constraints that are defined in terms of outage probability of the signal-to-interference-and-noise ratio (SINR) at a target level. Our numerical results, based on solving the design problem using known convex optimization algorithms, show that both design formulations lead to desired outcomes and satisfy the specified QoS requirements.