الفهرس 
Introductionيوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
The Non-orthogonal multiple access (NOMA), the ambient backscatter communication (AmBC), the reconfigurable intelligent surface (RIS), and the underwater optical
wireless communication (UOWC) have gained a lot of interest as paradigms of technologies that drive the development of the next generation of communication systems.
NOMA is a key player for enhancing spectrum utilization either by multiplexing multiple messages for the same user or allowing multi-users access, while AmBC shows great
potential for enhancing both spectrum and energy efficiency for battery-limited devices.
Besides, RIS provides programming capabilities over wireless channels, and UOWC has
crucial application scenarios. In this thesis, the performance of a downlink NOMA multiplexing based symbiotic-radio (SR) AmBC system is analyzed over Nakagami-m fading
channels. New closed-form expressions for the exact and asymptotic outage probabilities (OPs) and ergodic capacity (EC) are derived. Moreover, we analyze the diversity
order and the influence of the system parameters on the outage performances. Besides,
we proposed a power allocation optimization technique to achieve an outage-optimal
performance. Through representative Monte-Carlo simulations, we have verified the analytical results. Finally, we compared the performance of the proposed system against a
benchmark OMA-based system.
In the second part of this thesis, we investigate the performance of a NOMA-based
RIS-assisted hybrid radio frequency (RF)-UOWC system, where a ship works as a relay
that redirects the received signal from a base station (BS) to two underwater destinations
simultaneously. Due to the interruption of the direct link between the base station and the
ship floating on the surface of the water, communication will be carried out via an RIS
fixed to an intermediate building. In this part, we provide new analytical expressions for
the outage probability (OP), asymptotic analyses of the OP, and diversity order (D) to gain
i
insights into the system performance. In the end, we illustrated that the NOMA-based
RIS-assisted system significantly improves the outage performance of hybrid RF-UWOC
systems over a benchmark system.
Finally, we provide an experimental implementation of the NOMA-based transmitter.
We utilize NI USRP-2942 with NI-LabVIEW software to experimentally implement a
two-user downlink NOMA-based phase-shift keying (PSK) transmitter.