The paper proposes a novel modulation scheme for RIS-assisted symbiotic radio (SR) systems to address the ambiguity problem. The key idea is to divide the RIS phase-shift matrix into two components: the symbol-invariant component used to assist the primary transmission, and the symbol-varying component used to carry the secondary signal.
To optimize these two components, the authors focus on the detection of the composite signal formed by the primary and secondary signals, and formulate a problem to minimize the bit error rate (BER) of the composite signal. By solving this problem, they derive the closed-form solution of the optimal symbol-invariant and symbol-varying components, which is related to the channel strength ratio of the direct link to the reflecting link.
The proposed modulation scheme can address the ambiguity problem by regarding the symbol-invariant component as a virtual direct link, and at the same time help enhance the primary transmission when the direct link is weak. Theoretical BER performance analysis is provided, and simulation results demonstrate the superiority of the proposed scheme over conventional modulation schemes.
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by Hu Zhou,Bowe... às arxiv.org 04-29-2024
https://arxiv.org/pdf/2311.01167.pdfPerguntas Mais Profundas