Power Allocation in MIMO Wireless Systems Subject to Long-Term, Short-Term, and Per-Antenna Power Constraints

This paper considers several fading channel models for which the authors aim to maximize ergodic capacity subject to different power constraints assuming that Channel State Information (CSI) is available at both the transmitter and the receiver. This paper characterizes the optimal power allocation structure in the Single-Input-Single-Output (SISO), Multiple-Input-Single-Output (MISO), and Multiple-Input-Multiple-Output (MIMO) models subject to long- and short-term power constraints. The optimal power policy in each of the channel models depends upon the ratio of the two power constraints and the average Signal-to-Noise-Ratio (SNR) of the system.