On the Feasibility of Wireless Energy Transfer Using Massive Antenna Arrays

TL;DR

This paper demonstrates that massive antenna arrays significantly enhance wireless energy transfer range and efficiency, reducing energy requirements and outage probability, especially with line-of-sight conditions and multiple antennas.

Contribution

It provides an analytical framework showing how massive MIMO arrays improve wireless energy transfer performance and efficiency over fading channels.

Findings

Massive antenna arrays increase WET range for a given outage probability.

Using multiple antennas reduces the required downlink energy for reliable transfer.

Line-of-sight conditions improve outage performance.

Abstract

We illustrate potential benefits of using massive antenna arrays for wireless energy transfer (WET). Specifically, we analyze probability of outage in WET over fading channels when a base station (BS) with multiple antennas beamforms energy to a wireless sensor node (WSN). Our analytical results show that by using massive antenna arrays, the range of WET can be increased for a given target outage probability. We prove that by using multiple-antenna arrays at the BS, a lower downlink energy is required to get the same outage performance, resulting into savings of radiated energy. We show that for energy levels used in WET, the outage performance with least-squares or minimum mean-square error channel estimates is same as that obtained based on perfect channel estimates. We observe that a strong line-of-sight component between the BS and WSN lowers outage probability. Furthermore, by deploying more antennas at the BS, a larger energy can be transferred reliably to the WSN at a given target outage performance for the sensor to be able to perform its main tasks. In our numerical examples, the RF power received at the input of the sensor is assumed to be on the order of a mW, such that the rectenna operates at an efficiency in the order of 50 %.