Save-then-transmit scheme for fading channels with random energy harvesters

In this paper, a point-to-point fading channel with the transmitter powered by energy harvester is considered. On account of the battery half-duplex constraint, this paper adopts a save-then-transmit scheme: the transmitter first harvests energy, and then stops EH to transmit information with all accumulated energy. Obviously, for the save-then-transmit scheme, a proper stopping time needs to be determined, since larger EH duration provides more the accumulated energy while decreases the average throughput. First, this paper proves the existence of the optimal stopping rule and shows that this rule has a state-dependent “threshold-based” structure for the fading channel scenario. Then, the corresponding threshold and the maximum throughput are efficiently computed by a proposed algorithm.