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On the performance of active RIS-enhanced NOMA systems with spectrum sharing mechanisms
Minh Tran1, Minh Bui Vu2, Sang Quang Nguyen3
1Advanced Intelligent Technology Research Group, Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
Plos One
|November 25, 2025
Summary
An active reconfigurable intelligent surface (ARIS) enhances non-orthogonal multiple access (NOMA) networks in spectrum sharing. ARIS outperforms passive RIS and OMA, improving reliability and spectral efficiency.
Area of Science:
- Wireless communication networks
- Signal processing
- Information theory
Background:
- Cognitive spectrum sharing enables efficient spectrum utilization.
- Non-orthogonal multiple access (NOMA) improves spectral efficiency but faces interference challenges.
- Reconfigurable intelligent surfaces (RIS) can optimize wireless environments, but active RIS offers enhanced capabilities.
Purpose of the Study:
- To analyze the performance of a downlink NOMA network assisted by an active RIS in a cognitive spectrum-sharing scenario.
- To compare the proposed ARIS-assisted NOMA architecture with passive RIS (PRIS) and orthogonal multiple access (OMA).
- To derive performance metrics and optimize power allocation for enhanced network efficiency.
Main Methods:
- Derivation of closed-form expressions for outage probability (OP), throughput, and energy efficiency (EE) under Nakagami-m fading.
- Asymptotic analysis of OP to determine achievable diversity order.
- Formulation and solution of an optimization problem for NOMA power allocation coefficient to minimize OP.
- Monte Carlo simulations for validation.
Main Results:
- ARIS significantly mitigates inter-user interference and overcomes multiplicative fading compared to PRIS and OMA.
- Exact expressions for OP, throughput, and EE were derived and validated.
- Asymptotic analysis revealed the diversity order.
- Optimized NOMA power allocation successfully minimized OP.
Conclusions:
- The proposed ARIS-assisted NOMA architecture demonstrates superior performance in terms of OP, throughput, and EE.
- ARIS has the potential to significantly enhance spectral efficiency, reliability, and coverage in next-generation spectrum-sharing NOMA networks.
- Active RIS offers distinct advantages over passive RIS in complex wireless environments.
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