Transmission over fading channels with channel side information and delay constraint

We consider a block flat fading channel, where both the transmitter and receiver have perfect knowledge of the channel gain of the current block. For a delay constraint of K blocks, we derive the optimum power adaptation strategy that would maximize the expected capacity over K blocks, assuming that a Gaussian codebook is to be used. Such an online strategy results in a one-block transmission scheme for low SNRs, while for higher SNRs it results in an ´online´ waterfilling algorithm. Significant capacity gains are afforded by the strategy at lower SNRs.