Optimal Energy Beamforming for Distributed Wireless Power Transfer over Frequency-Selective Channels

Abstract

This paper analyzes the optimal transmission strategy and power allocation for a distributed wireless power transfer (WPT) system operating over frequency-selective fading channels. We consider K coordinated energy transmitters (CETs) coherently transmitting energy to a single user over N K subchannels with individual power constraints. To maximize the total harvested energy, we derive the optimal co-phasing power allocation rule which has the following properties: 1) For any given subchannel, if the optimal power allocation of one CET is zero, then the power allocated by all the other K 1 CETs to that subchannel is also zero (i.e., the subchannel is inactive); 2) For the non-zero power subc..