LoRa Backscatter Communications: Temporal, Spectral, and Error Performance Analysis

Abstract

LB communication systems can be considered as a potential candidate for ultra LPWAN because of their low cost and low power consumption. In this paper, we comprehensively analyze LB modulation from various aspects, i.e., temporal, spectral, and error performance characteristics. First, we propose a signal model for LB signals that accounts for the limited number of loads in the tag. Then, we investigate the spectral properties of LB signals, obtaining a closed-form expression for the power spectrum. Finally, we derived the SER of LB with two decoders, i.e., the ML and FFT decoders, in both AWGN and double Nakagami-m fading channels. The spectral analysis shows that out-of-band emissions for LB satisfy the ETSI regulation only when considering a relatively large number of loads. For the error performance, unlike conventional LoRa, the FFT decoder is not optimal. Nevertheless, the ML decoder can achieve a performance similar to conventional LoRa with a moderate number of loads.