Interference-Free ZT DFT-s-OFDM-Based Symbiotic Backscatter Communication

This article presents a unique lightweight and interference-free backscatter communication (BC) scheme based on zero tail discrete Fourier transform spread OFDM (ZT DFT-s-OFDM) waveform signals. In the proposed approach, the ZT region of the waveform is exploited to accommodate backscatter transmissions using delay shift keying (DSK) modulation. A backscatter device (BD) equipped with modulator based on acoustic-wave delay circuits conveys information by introducing deterministic delay shifts within the uncorrupted ZT portion of the ZT DFT-s-OFDM symbol, thus ensuring complete time-domain separation between the primary and BD signals. This approach effectively eliminates direct-link interference (DLI) while maintaining full compatibility with conventional receivers. To address the channel-estimation challenge, a low-complexity, non-coherent detector is developed, and its analytical performance is derived and validated through simulation. The simulations show consistency between the analytical and simulation results, demonstrating that the proposed design achieves a probability of missed detection (PMD) as low as 10−3at 30 dB, therefore, confirming its robustness and suitability for low-power BC applications.