  Far-field Wireless Power Transfer (WPT) has emerged as a potential power
source for the Internet of Things (IoT) and Wireless Sensor Network (WSN).The
expansion of the power transfer range is one of the key challenges to make the
technology viable. In this paper, we experimentally study a channel-adaptive
joint beamforming and waveform architecture to expand the power transfer range.
WPT experiments have been conducted in a variety of wireless channels at
various distances in a realistic indoor environment. The measurement data have
been fitted using a simple analytical model to analyze the output DC power and
achievable range improvement depending on the signal design schemes and the
number of tones and antennas. The model shows a clear relationship between
signal design versus output DC power and achievable range, and highlight the
significant benefit of the proposed architecture to expand the power transfer
range.
