Performance Analysis and Optimization for SWIPT Wireless Sensor Networks

This paper investigates and optimizes the performance of simultaneous wireless information and power transfer (SWIPT) in wireless sensor networks over Nakagami- $m$ fading channels. In the considered system, there is one mobile reader ( $R$ ), which is equipped with one transmit antenna and one receive antenna, and a group of passive sensors. The information delivery includes two stages: 1) $R$ broadcasts a command with radio-frequency energy to the sensors, which adopt time splitting (TS)/power splitting (PS) schemes to harvest energy and 2) sensors deliver their information to $R$ over orthogonal channels by using the harvested energy. In this paper, we propose a unified framework to study and optimize the impact of SWIPT on the system performance with both TS and PS schemes. First, we characterize the probability density function and cumulative distribution function of the signal-to-interference-plus-noise-ratio in high signal-to-noise ratio region, then we study the outage and ergodic capacity performance of the backward links. The approximated closed-form expressions for the outage probability and ergodic capacity are derived and validated through Monte Carlo simulations. Finally, we also evaluate the energy efficiency of the target system, and propose an optimal splitting scheme for TS and PS to maximize the throughput of the target system.