Designing prefix code to save energy for wirelessly powered wireless sensor networks

Abstract

In the Internet of Things, wireless sensor networks (WSNs) are widely deployed. In recent years, wirelessly powered WSNs or battery-free WSNs (BF-WSNs), in which the nodes harvest energy from radio signals in the environment, have been emerging to support sustainable operation for WSNs. It is significant to design an energy-efficient data delivery scheme for the BF-WSNs. In this study, the authors propose the prefix code based scheme (PCBS) to save energy in data delivery by making use of the energy consumption disparity (ECD) between transmitting/receiving bit 0 and bit 1 in the existing non-modulation baseband transmission or carrier-modulation based passband transmission. The authors formulate an optimisation problem and use genetic algorithm to find its solution so that the energy-efficient prefix codebook is obtained. The codebook dilutes the ECD by containing the energy-consuming bit as few as possible, and the PCBS maps each m-bit data block into a prefix codeword in the codebook to conduct energy-efficient transmission at the transmitter and vice versa at the receiver. Both the experiments on wireless identification sensing platform and the simulations demonstrate that the proposed PCBS outperforms the existing schemes in terms of energy saving.