  In this paper, we propose a reconfigurable intelligent surface (RIS)-assisted
frequency-modulated (FM) differential chaos shift keying (DCSK) scheme with
simultaneous wireless information and power transfer (SWIPT), called
RIS-FM-DCSK-SWIPT scheme, for low-power, low-cost, and high-reliability
wireless communication networks. In particular, the proposed scheme is
developed under a non-linear energy-harvesting (EH) model which can accurately
characterize the practical situation. The proposed RIS-FM-DCSK-SWIPT scheme has
an appealing feature that it does not require channel state information, thus
avoiding the complex channel estimation. We further derive the closed-form
theoretical expressions for the energy shortage probability and bit error rate
(BER) of the proposed scheme over the multipath Rayleigh fading channel. In
addition, we investigate the influence of key parameters on the performance of
the proposed transmission scheme in two different scenarios, i.e., RIS-assisted
access point (RIS-AP) and dual-hop communication (RIS-DH). Finally, we carry
out various Monte-Carlo experiments to verify the accuracy of the theoretical
derivation, illustrate the performance advantage of the proposed scheme, and
give some design insights for future study.
