Energy Conservation Scheme for IEEE 802.15.4 Based Battery-free Wireless Sensor Networks

In Battery-free Wireless Sensor Network (BF-WSN), the nodes harvest energy from ambient energy sources to power their microprocessors, sensors, radio transceivers, etc. It is critical to design an energy conservation scheme for the nodes to save energy. Considering contemporary Wireless Sensor Network (WSN) adopts IEEE 802.15.4 standard in its Medium Access Control (MAC) layer and Physical (PHY) layer, we model the 802.15.4 based BF-WSN using Markov chain so that the expected number of packets waiting in the node's transmission/reception buffer and the buffer overflow probability are derived. In addition, the Optimization Problem (OP) is formulated that minimizes the node's energy consumption under the constraints on capacitor-charging time, buffer overflow probability, data rate, and the maximum number of transmission retrials set in the MAC layer. Moreover, the OP Based Energy Management Scheme (OBEMS) is presented, which uses the solution of the OP. Simulation results show the proposed scheme is able to reduce energy consumption while maintaining a higher Packet Delivery Ratio (PDR).