PADRE: Modulated Backscattering-Based PAssive Data REtrieval in Wireless Sensor Networks

The most difficult challenge for the design of wireless sensor networks (WSN) is to maintain long network lifetimes since the sensor nodes are severely energy-constrained. Traditional WSN assumes employment of conventional RF transmitters which consume most of the stored power on the sensor node. In this regard, modulated backscattering (MB) emerges as a promising communication technique alternative, in which the sensor nodes reflect the incident signal of an RF source and modulate their data on the reflected signal. With the use of MB, the power consumption of the nodes reduce drastically since it replaces the most power consuming component of a typical sensor node, i.e., the RF transmitter. In addition, the nodes acquire relatively long-range communication ability through MB. Furthermore, the incident RF power can be converted into DC power in order to drive the sensing and processing circuitries. This, in turn,i leads to the design of battery-free wireless passive sensor networks (WPSN), which stands as a radically distinct solution approach for the energy problems of WSN. The objective of this paper is to revisit the main design challenge of WSN from entirely different perspective. To this end, the fundamental principles of WPSN are first introduced. In addition, in order to realize the potential benefits of WPSN, a new clustering-based energy-efficient communication protocol, i.e., PADRE (PAssive Data REtrieval), is presented for WPSN operating via MB technique. Simulations show that PADRE protocol achieves high performance in terms communication reliability and network lifetime.