Power Control with Outage Capacity Constraints

This paper addresses the power distribution over K blocks of coded information to accommodate a certain rate for some probability in Rayleigh flat-fading channels given the causal channel state information at the transmitter (CSIT) and the channel statistics in the future. With such outage capacity constraint, time diversity can be accomplished by stochastically distributing the power among the blocks. For K=2, we derive the stochastic-optimal power policy in closed-form for transmit power minimization. For K>2, we propose to minimize the power by constraining an upper bound of the outage probability. In so doing, the problem becomes convex and permits a closed-form optimal power policy to be derived. Results demonstrate that the proposed power policy exploiting CSIT gives significant power reduction when compared to an equal-power policy for stringent outage settings