Performance Enhancement of Full-Duplex NOMA in RIS-Assisted UAV Networks Through Channel-Aware Transmission Switching

The integration of reconfigurable intelligent surfaces (RIS) and uncrewed aerial vehicles (UAVs) offers significant potential for enhancing spectral efficiency, connectivity, and coverage in future wireless networks. This paper examines a RIS-enabled, UAV-assisted non-orthogonal multiple access (NOMA) system, wherein the UAV operates in full-duplex mode to facilitate signal transmission. This work identifies the limitations of an existing joint transmission and selection combining (JT-SC) scheme, showing that simultaneous RIS and UAV transmissions can degrade system performance due to mutual interference and processing delays. However, the challenge of mitigating mutual interference and processing delays in simultaneous RIS and full-duplex UAV transmissions has not been adequately addressed in existing works, and a dynamic switching strategy between RIS and UAV based on channel conditions remains unexplored. To address these challenges, we propose a channel-aware hybrid switching (CA-HS) scheme that dynamically selects either RIS reflection or UAV transmission based on instantaneous channel conditions. Numerical and simulation results demonstrate that the proposed CA-HS scheme significantly improves both system throughput and reliability compared to existing baseline methods. Specifically, the achieved rate of the CA-HS scheme shows an improvement of approximately 8% and 20% compared to the UAV-only case and the JT-SC scheme, respectively, highlighting its effectiveness and practical relevance for next-generation wireless communication systems.