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Achieving low-power wide coverage and good spectral efficiency is one of the main objectives of next-generation wireless communication. Non-Orthogonal Multiple Access (NOMA)-assisted Ambient Backscatter Communication (AmBC) has proven to be capable of offering great spectral efficiency at low power. In contrast, Intelligent Reflecting Surface (IRS) has proven to be capable of improving coverage. Consequently, efforts have been made to integrate those technologies. However, thorough model development and analysis are necessary to benefit from such coexistence. In this study, we analyze the performance of a Power Domain (PD)-NOMA-enabled base station acting as a source in a multiple-user IRS-assisted AmBC system. The main approach we take is to use PD-NOMA to send a signal from the base station to the IRS that has both modulated (with a primary message) and unmodulated carrier components. In addition to relaying the primary message, the IRS will then send its (secondary) message to user devices utilizing the unmodulated carrier and Binary Phase-shift Keying (BPSK). Then, using a Band Pass Filter (BPF) and Successive Interference Cancellation (SIC), the user devices decode their respective messages from the received signals. To obtain further understanding, we derived novel closed-form expressions for the Outage Probabilities (OPs) and also provided asymptotic assessments of the OPs. Our results show that raising the IRS element count enhances the OPs. Additionally, devices' outage performance is impaired due to the imperfections in SIC. Furthermore, we found that a device's OP rises as the power allocation factor increases. Lastly, we found that the NOMA-based IRS-assisted system outperforms OMA-based systems in terms of outages. IEEE

Backscatter Communication (BackCom) has opened up various novel joint sensing and communication applications in the Internet of things (IoT) domain. In particular, the IoT devices in water bodies have seen a recent paradigm shift toward more sustainability with the advent of Acoustic Backscatter Communication (A-BackCom). However, despite the low-power budget of A-BackCom, it only relies on harvesting energy from the source (acoustic) signal. In this article, we survey some Multi-Source Energy Harvesting (MSEH) techniques from terrestrial BackCom which can be adopted to enhance the sustainability of ABackCom. We also show and discuss a case study where multiple energy sources are harvested in the water body and how much the harvested energy could extend the operation A-BackCom. Further, we discuss some challenges of MSEH in A-BackCom. Results from our case study show that MSEH in A-Back-Com could extend the lifetime of an A-BackCom node by allowing anrecharging time as low as 5.7 ms, even without an acoustic carrier signal. © 1979-2012 IEEE.