Chirp-Based Multi-Device Ambient Backscatter Communication and Sensing Enabled by OFDM-AFDM Symbiotic Radio

TL;DR

This paper introduces a novel symbiotic radio system that enables simultaneous sensing and backscatter communication within the same spectrum using orthogonal waveform-domain multiplexing, enhancing interference mitigation and signal detectability.

Contribution

The paper proposes a chirp-based AFDM waveform for integrated sensing and backscatter communication, enabling interference-free coexistence with primary signals and suppression of inter-device interference.

Findings

Effective interference mitigation without primary link error increase

Enhanced detection and sensing reliability for backscatter devices

Superior performance demonstrated through comprehensive simulations

Abstract

This paper presents a novel symbiotic radio system for integrated sensing and backscatter communication (ISABC) technique that enables signal-domain interference-free coexistence of the primary communication signal and the backscatter communication (BC) signal within the same spectrum. The proposed system design allows simultaneous backscatter devices (BDs) sensing and data transmission without mutual interference by exploiting waveform-domain orthogonality between orthogonal frequency division multiplexing (OFDM) and affine frequency domain multiplexing (AFDM) signals. Specifically, a chirp-based AFDM waveform is adopted due to its inherent processing gain, which enhances the detectability and reliability of the weak backscatter signal while simultaneously supporting high-resolution sensing. Unlike conventional methods that attempt to suppress direct-link interference (DLI), this approach embeds the backscatter transmission within the affine domain while maintaining reliable OFDM-based primary communication. Furthermore, by assigning distinct affine-domain shifts to each backscatter device, the proposed framework inherently suppresses inter-backscatter device interference (IBDI). Comprehensive simulation results demonstrate that the proposed coexistence scheme effectively mitigates interference without affecting the error rate of the primary link and improves the miss-detection probability performance of the BC, making it a promising candidate for future low-power and interferenceresilient systems.