Ambient Backscattering - An Efficient and Reliable Approach for Agriculture

Abstract

Radio Frequency Identification (RFID) systems have attracted increasing attentions from both academic circles and industrial communities over the past two decades. Energy harvesting is a key technique that can be used to overcome the barriers that prevent the real world deployment of WSN’s. In particular, solar energy harvesting has been commonly used to overcome this barrier. However, it should be noted that WSNs operating on solar power suffer from energy shortage during night times. Therefore, to solve this problem, we exploit the use of TV broadcasts airwaves as energy sources to power wireless sensor nodes. This paper introduces a novel wireless leaf temperature sensor that utilizes ambient FM backscattering for smart agricultural applications. The sensor is based on an ultra low power microcontroller, a sensor board and a RF front-end for wireless communication. The sensor communicates using backscatter radio principles on ambient FM station signals using AM modulation with FM0 encoding. The prototype features an effective operation up to ranges of 0.5 m by backscattering sensor information at 50 bps and 500 bps using an ambient FM radio signal inside alaboratory setup. A high percentage of bits will be clearly visible up to 2 m at 50 bps.