Estimation and Analysis of Maximum Energy Harvested in RF-EH Wireless System Over Different Fading Channels

Abstract

Parameter estimation is an important problem in practical wireless systems and networks. Specifically, accurate estimation of harvested energies is vital in autonomous, green wireless systems and networks whose essential energy resources are ambient radio frequency (RF) signals. In this paper, I address the problem of estimating the maximum energy harvested among multiple energy harvesting (EH) relays in a double-hop EH relay-assisted cooperative wireless system. In the system considered, multiple EH relays harvest energy from RF signals they receive from the RF source over Rayleigh fading channels. I formally state the maximum harvested energy estimation problem in the presence of additive white noise. I derive analytical expressions for the exact minimum mean squared error (MMSE) estimator and MMSE. Further, I obtain an expression for the number of measurements for a special scenario where MMSE and Cramer-Rao lower bound (CRLB) are equal. I further extend the analysis and simulations for Rayleigh fading with shadowing and Nakagami fading to get more analytical and quantitative insights. Finally, the MMSE of the proposed model is compared with a benchmark model that includes quantization noise and multiplicative noise. The analysis is useful for further investigating order statistics of harvested energies and application in green cooperative energy harvesting Internet of Things (IoT)-enabled wireless systems.