On the sufficiency of power control for a class of channels with feedback

This paper shows that, for a particular class of channels that we believe applies to many physical problems of interest, the utility of feedback, insofar as channel capacity is concerned, is simply for allowing the transmitter to perform power control. This class of channels, which assumes noiseless feedback but allows for the feedback to be of arbitrary rate, includes channels that model slow, flat fading channels with variable input power. Thus our result gives some guidance on the design of effective transmission schemes for slow, flat fading channels with feedback.