Rate-Optimal Power Adaptation in Average and Peak Power Constrained Fading Channels

The power adaptation strategy which maximises the average information rate that can be reliably transmitted over average and peak power constrained block-fading single-user discrete-time channels, in which perfect transmitter and receiver channel state information (CSI) are available and in which any transmitted codeword spans a single fading block, is characterised by means of a theorem and subsequently computed numerically in different scenarios. The results reveal striking differences between the well known water-pouring power adaptation strategy which is optimal from a capacity point of view in the case of stationary and ergodic fading channels where the input is subject to an average power constraint only, and the rate-optimal power adaptation strategy of the average and peak power constrained block-fading channels studied in this document.