Power Allocation in Wireless Systems Subject to Long-Term and Short-Term Power Constraints
The authors consider several fading channel models for which they aim to maximize ergodic capacity assuming that Channel State Information (CSI) is available at both the receiver and the transmitter. They characterize 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 both long-term 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. They characterize the conditions, in which the short-term power constraint can be eliminated without being violated in the optimal power policy.