Experimental Study on Battery-less Sensor Network Activated by Multi-point Wireless Energy Transmission

TL;DR

This study empirically demonstrates that multi-point wireless energy transmission with carrier shift diversity effectively activates battery-less sensors indoors, achieving full coverage and overcoming limitations of single-point transmission.

Contribution

It introduces a practical implementation and experimental validation of multi-point wireless energy transmission with carrier shift diversity for battery-less sensor activation.

Findings

Proposed scheme achieves 100% coverage in indoor environments.

Battery-less sensors require 142 μW power consumption and 400 μW received power for activation.

Multi-point transmission outperforms single-point in coverage, which is around 84%.

Abstract

This paper empirically validates battery-less sensor activation via wireless energy transmission to release sensors from wires and batteries. To seamlessly extend the coverage and activate sensor nodes distributed in any indoor environment, we proposed multi-point wireless energy transmission with carrier shift diversity. In this scheme, multiple transmitters are employed to compensate path-loss attenuation and orthogonal frequencies are allocated to the multiple transmitters to avoid the destructive interference that occurs when the same frequency is used by all transmitters. In our previous works, the effectiveness of the proposed scheme was validated theoretically and also empirically by using just a spectrum analyzer to measure the received power. In this paper, we develop low-energy battery-less sensor nodes whose consumed power and required received power for activation are respectively 142 uW and 400 uW. In addition, we conduct indoor experiments in which the received power and activation of battery-less sensor node are simultaneously observed by using the developed battery-less sensor node and a spectrum analyzer. The results show that the coverage of single-point and multi-point wireless energy transmission without carrier shift diversity are, respectively, 84.4% and 83.7%, while the coverage of the proposed scheme is 100%. It can be concluded that the effectiveness of the proposed scheme can be verified by our experiments using real battery-less sensor nodes.