Robust and constrained downlink beamforming

When antenna arrays are introduced in a cellular system, one critical aspect is the design of beamformers for downlink transmission. We extend a recently proposed strategy for optimal downlink beamforming to give increased robustness to channel uncertainties and to incorporate constraints on the dynamic range. The solution can be efficiently calculated using semidefinite optimization. In a few cases, the optimal solution is given by a time-varying beamformer. We explore the performance of these modified algorithms.