Dynamic power allocation in MIMO fading systems without channel distribution information

Abstract

This paper considers dynamic power allocation in MIMO fading systems with unknown channel state distributions. First, the ideal case of perfect instantaneous channel state information at the transmitter (CSIT) is treated. Using the drift-plus-penalty method, a dynamic power allocation policy is developed and shown to approach optimality, regardless of the channel state distribution and without requiring knowledge of this distribution. Next, the case of delayed and quantized channel state information is considered. Optimal utility is fundamentally different in this case, and a different online algorithm is developed that is based on convex projections. The proposed algorithm for this delayed-CSIT case is shown to have an O (δ) optimality gap, where δ is the quantization error of CSIT.