# Wirelessly Powered Backscatter Communications: Waveform Design and SNR-Energy Tradeoff

## TL;DR

This paper investigates the fundamental tradeoff in wirelessly powered backscatter communications between energy harvesting and communication reliability, proposing waveform optimization to enhance performance.

## Contribution

It introduces a systematic method to optimize multisine waveform weights for better SNR-energy tradeoff in backscatter systems.

## Key findings

- Using multiple frequency components improves SNR-energy performance.
- Waveform adaptation exploits rectifier nonlinearity and frequency diversity.
- Significant gains confirmed through performance evaluations.

## Abstract

This paper shows that wirelessly powered backscatter communications is subject to a fundamental tradeoff between the harvested energy at the tag and the reliability of the backscatter communication, measured in terms of SNR at the reader. Assuming the RF transmit signal is a multisine waveform adaptive to the channel state information, we derive a systematic approach to optimize the transmit waveform weights (amplitudes and phases) in order to enlarge as much as possible the SNRenergy region. Performance evaluations confirm the significant benefits of using multiple frequency components in the adaptive transmit multisine waveform to exploit the nonlinearity of the rectifier and a frequency diversity gain.