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Performance Analysis of Double Reconfigurable Intelligent Surfaces Assisted NOMA Networks

Xuehua Li, Xuanhao Lian, Xinwei Yue, Zhiping Lu, Chongwen Huang, Tianwei Hou

TL;DR

This work analyzes a PRIS-ARIS-NOMA system over cascaded Rician and Nakagami-$m$ fading, deriving closed-form and asymptotic outage probabilities and ergodic data rates for two non-orthogonal users, including both ipSIC and pSIC cases. Diversity orders and ergodic-rate slopes are established, highlighting the impact of ARIS element count and residual interference on high-SNR performance. The study also quantifies delay-limited and delay-tolerant system throughputs, showing PRIS-ARIS-NOMA outperforms PRIS-ARIS-OMA and double-PRIS-NOMA, with ARIS providing enhanced resilience against double fading. These insights support design choices for multi-RIS, RIS-amplification aided NOMA in future wireless networks, emphasizing the role of active RIS and coherent phase shifting in complex cascaded channels.

Abstract

This paper introduces double cascaded reconfigurable intelligent surfaces (RISs) to non-orthogonal multiple access (NOMA) networks over cascaded Rician fading and Nakagami-$m$ fading channels, where two kinds of passive RIS (PRIS) and active RIS (ARIS) are taken into consideration, called PRIS-ARIS-NOMA networks. Additionally, new closed-form and asymptotic expressions for outage probability and ergodic data rate of two non-orthogonal users are derived with the imperfect/perfect successive interference cancellation schemes. The scenario is modelled around two non-orthogonal users and focuses on analyzing their communication characteristics. Based on the approximate results, the diversity orders and ergodic data rate slopes of two users are obtained in the high signal-to-noise ratios. In addition, the system throughput of PRIS-ARIS-NOMA in delay-limited mode and delay-tolerant mode are discussed according to the outage probability and ergodic data rate. The simulation results verify the correctness of the formulas and yields the following insights: 1) The outage behaviors of PRIS-ARIS-NOMA outperforms than that of PRIS-ARIS assisted orthogonal multiple access (OMA); 2)Use of PRIS-ARIS-NOMA is better than use of PRIS-ARIS-OMA in small transmit power threshold scenarios 3) By increasing the number of reflecting elements of RISs, the PRIS-ARIS-NOMA is able to achieve the enhanced outage performance; and 4) The PRIS-ARIS-NOMA has the higher ergodic data rate and system throughput than double PRISs-NOMA.

Performance Analysis of Double Reconfigurable Intelligent Surfaces Assisted NOMA Networks

TL;DR

This work analyzes a PRIS-ARIS-NOMA system over cascaded Rician and Nakagami- fading, deriving closed-form and asymptotic outage probabilities and ergodic data rates for two non-orthogonal users, including both ipSIC and pSIC cases. Diversity orders and ergodic-rate slopes are established, highlighting the impact of ARIS element count and residual interference on high-SNR performance. The study also quantifies delay-limited and delay-tolerant system throughputs, showing PRIS-ARIS-NOMA outperforms PRIS-ARIS-OMA and double-PRIS-NOMA, with ARIS providing enhanced resilience against double fading. These insights support design choices for multi-RIS, RIS-amplification aided NOMA in future wireless networks, emphasizing the role of active RIS and coherent phase shifting in complex cascaded channels.

Abstract

This paper introduces double cascaded reconfigurable intelligent surfaces (RISs) to non-orthogonal multiple access (NOMA) networks over cascaded Rician fading and Nakagami- fading channels, where two kinds of passive RIS (PRIS) and active RIS (ARIS) are taken into consideration, called PRIS-ARIS-NOMA networks. Additionally, new closed-form and asymptotic expressions for outage probability and ergodic data rate of two non-orthogonal users are derived with the imperfect/perfect successive interference cancellation schemes. The scenario is modelled around two non-orthogonal users and focuses on analyzing their communication characteristics. Based on the approximate results, the diversity orders and ergodic data rate slopes of two users are obtained in the high signal-to-noise ratios. In addition, the system throughput of PRIS-ARIS-NOMA in delay-limited mode and delay-tolerant mode are discussed according to the outage probability and ergodic data rate. The simulation results verify the correctness of the formulas and yields the following insights: 1) The outage behaviors of PRIS-ARIS-NOMA outperforms than that of PRIS-ARIS assisted orthogonal multiple access (OMA); 2)Use of PRIS-ARIS-NOMA is better than use of PRIS-ARIS-OMA in small transmit power threshold scenarios 3) By increasing the number of reflecting elements of RISs, the PRIS-ARIS-NOMA is able to achieve the enhanced outage performance; and 4) The PRIS-ARIS-NOMA has the higher ergodic data rate and system throughput than double PRISs-NOMA.
Paper Structure (26 sections, 11 theorems, 54 equations, 21 figures, 1 table)

This paper contains 26 sections, 11 theorems, 54 equations, 21 figures, 1 table.

Table of Contents

  1. Introduction
  2. Motivations and Contributions
  3. Organizations and Notations
  4. System Model
  5. Signal Model
  6. Channel Statistical Properties
  7. Outage Probability
  8. The Outage Probability of $D_n$
  9. The Outage Probability of $D_m$
  10. The Outage Probability of the OMA Benchmark
  11. Diversity Analysis
  12. Delay-limited Transmission
  13. Ergodic Data Rate Analysis
  14. The Ergodic Data Rates of $D_n$
  15. The Ergodic Data Rates of $D_m$
  16. ...and 11 more sections

Key Result

Theorem 1

Under cascaded Rician fading and Nakagami-$m$ fading channels, the closed-form expression for outage probability of $D_n$ with ipSIC for PRIS-ARIS-NOMA can be expressed as where $\varpi = 1$, $\overline {{\lambda _n}} = {\eta ^{ - 4}}d_{h1}^\alpha d_{h2}^\alpha d_{g1}^\alpha d_{gn}^\alpha$. For bringing into Gauss-Laguerre quadrature, ${{x_u}}$ is the $u$-th zero point of Laguerre polynomial ${

Figures (21)

  • Figure 1: System model of PRIS-ARIS-NOMA.
  • Figure : Fig. 2: Outage probability versus the transmitting power of the BS for PRIS-ARIS-NOMA.
  • Figure : Fig. 3: Outage probability versus the total power consumption.
  • Figure : Fig. 4: Outage probability versus the transmitting power of the BS for PRIS-ARIS-NOMA.
  • Figure : Fig. 5: Outage probability versus the transmitting power of the BS for PRIS-ARIS-NOMA.
  • ...and 16 more figures

Theorems & Definitions (23)

  • Theorem 1
  • proof
  • Corollary 1
  • Theorem 2
  • proof
  • Theorem 3
  • Corollary 2
  • Remark 1
  • Corollary 3
  • proof
  • ...and 13 more