Phase-Assisted Modulation and Non-Coherent Detection for Ambient Backscatter Communication

Abstract

Ambient backscatter communication is regarded as a promising technology for the ambient Internet of Things, enabling large-scale connectivity with low power consumption and low complexity. Existing symbol detection methods for conventional on-off keying (OOK) modulation suffer from severe performance degradation, when the amplitudes of the direct-link and the composite direct-backscatter channel are comparable. To address this issue, we propose a novel phaseassisted modulation scheme termed as intra-symbol phaseshift OOK (ISPS-OOK), which introduces phase diversity to improve detection performance. Specifically, we first present the coding and modulation design of ISPS-OOK and propose an energy difference detector (EDD) for ISPS-OOK. Furthermore, we derive closed-form expressions of the bit error rate (BER) and the optimal detection threshold, together with their asymptotic forms. To avoid requiring channel state information, as well as the ambient signal power and noise power, we propose a blind detection threshold estimation method by estimating the threshold-required parameters. Numerical results verify the theoretical analysis and demonstrate the effectiveness of the proposed EDD for ISPS-OOK.