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Exploiting Active RIS in NOMA Networks with Hardware Impairments

Xinwei Yue, Meiqi Song, Chongjun Ouyang, Yuanwei Liu, Tian Li, Tianwei Hou

TL;DR

This work analyzes active RIS (ARIS) assisted NOMA networks under hardware impairments (HIS) over cascade Nakagami-$m$ fading, deriving exact and asymptotic outage probability and ergodic rate expressions for ipSIC and pSIC decoding. It reveals that HIS induces rate ceilings and zero multiplexing gains at high SNR, while ARIS’s amplification and active reflection can still offer outage and rate benefits over PRIS and conventional relaying. The study provides diversity-order results tied to the number of ARIS elements and channel orders, and it quantifies energy efficiency in both delay-limited and delay-tolerant regimes, with ARIS-NOMA-HIS outperforming ARIS-OMA-HIS and PRIS-NOMA-HIS in simulations. Overall, the paper demonstrates the potential of ARIS to enhance spectral efficiency and energy efficiency in NOMA networks despite practical hardware imperfections, and it identifies key design trade-offs involving $L$, $\beta$, and HAR. The theoretical framework and benchmarks offer guidance for deploying ARIS in future 6G-like systems under realistic hardware constraints.

Abstract

Active reconfigurable intelligent surface (ARIS) is a promising way to compensate for multiplicative fading attenuation by amplifying and reflecting event signals to selected users. This paper investigates the performance of ARIS assisted non-orthogonal multiple access (NOMA) networks over cascaded Nakagami-m fading channels. The effects of hardware impairments (HIS) and reflection coefficients on ARIS-NOMA networks with imperfect successive interference cancellation (ipSIC) and perfect successive interference cancellation (pSIC) are considered. More specifically, we develop new precise and asymptotic expressions of outage probability and ergodic data rate with ipSIC/pSIC for ARIS-NOMA-HIS networks. According to the approximated analyses, the diversity orders and multiplexing gains for couple of non-orthogonal users are attained in detail. Additionally, the energy efficiency of ARIS-NOMA-HIS networks is surveyed in delay-limited and delay-tolerant transmission schemes. The simulation findings are presented to demonstrate that: i) The outage behaviors and ergodic data rates of ARIS-NOMA-HIS networks precede that of ARIS aided orthogonal multiple access (OMA) and passive reconfigurable intelligent surface (PRIS) aided OMA; ii) As the reflection coefficient of ARIS increases, ARIS-NOMA-HIS networks have the ability to provide the strengthened outage performance; and iii) ARIS-NOMA-HIS networks are more energy efficient than ARIS/PRIS-OMA networks and conventional cooperative schemes.

Exploiting Active RIS in NOMA Networks with Hardware Impairments

TL;DR

This work analyzes active RIS (ARIS) assisted NOMA networks under hardware impairments (HIS) over cascade Nakagami- fading, deriving exact and asymptotic outage probability and ergodic rate expressions for ipSIC and pSIC decoding. It reveals that HIS induces rate ceilings and zero multiplexing gains at high SNR, while ARIS’s amplification and active reflection can still offer outage and rate benefits over PRIS and conventional relaying. The study provides diversity-order results tied to the number of ARIS elements and channel orders, and it quantifies energy efficiency in both delay-limited and delay-tolerant regimes, with ARIS-NOMA-HIS outperforming ARIS-OMA-HIS and PRIS-NOMA-HIS in simulations. Overall, the paper demonstrates the potential of ARIS to enhance spectral efficiency and energy efficiency in NOMA networks despite practical hardware imperfections, and it identifies key design trade-offs involving , , and HAR. The theoretical framework and benchmarks offer guidance for deploying ARIS in future 6G-like systems under realistic hardware constraints.

Abstract

Active reconfigurable intelligent surface (ARIS) is a promising way to compensate for multiplicative fading attenuation by amplifying and reflecting event signals to selected users. This paper investigates the performance of ARIS assisted non-orthogonal multiple access (NOMA) networks over cascaded Nakagami-m fading channels. The effects of hardware impairments (HIS) and reflection coefficients on ARIS-NOMA networks with imperfect successive interference cancellation (ipSIC) and perfect successive interference cancellation (pSIC) are considered. More specifically, we develop new precise and asymptotic expressions of outage probability and ergodic data rate with ipSIC/pSIC for ARIS-NOMA-HIS networks. According to the approximated analyses, the diversity orders and multiplexing gains for couple of non-orthogonal users are attained in detail. Additionally, the energy efficiency of ARIS-NOMA-HIS networks is surveyed in delay-limited and delay-tolerant transmission schemes. The simulation findings are presented to demonstrate that: i) The outage behaviors and ergodic data rates of ARIS-NOMA-HIS networks precede that of ARIS aided orthogonal multiple access (OMA) and passive reconfigurable intelligent surface (PRIS) aided OMA; ii) As the reflection coefficient of ARIS increases, ARIS-NOMA-HIS networks have the ability to provide the strengthened outage performance; and iii) ARIS-NOMA-HIS networks are more energy efficient than ARIS/PRIS-OMA networks and conventional cooperative schemes.
Paper Structure (20 sections, 20 theorems, 58 equations, 11 figures, 1 table)

This paper contains 20 sections, 20 theorems, 58 equations, 11 figures, 1 table.

Table of Contents

  1. Introduction
  2. Motivation and Contributions
  3. Organization and Notations
  4. Network Model
  5. Signal Model
  6. ARIS-OMA with Hardware Impairments
  7. Outage probability
  8. The Outage Probability of User g
  9. The Outage Probability of User f
  10. The Outage Probability of User o
  11. Diversity Analysis
  12. Delay-Limited Transmission
  13. Ergodic Data rate
  14. The Ergodic Data Rate of ARIS networks
  15. The Ergodic Data Rate of PRIS networks
  16. ...and 5 more sections

Key Result

Theorem 1

In terms of cascade Nakagami-$m$ fading channels, the outage probability of user $g$ with ipSIC for ARIS-NOMA-HIS networks can be approximated as where ${\Psi _g} = \frac{{K!}}{{\left( {K - g} \right)!\left( {g - 1} \right)!}}$, ${\psi _g} = \Gamma \left( {m_g} \right){\left[ {\Gamma \left( {{b_g} + 1} \right)} \right]^{g + k}}$, ${\varphi _g} = d_{br}^\alpha d_{rg}^\alpha {\varsigma _g}\varpi {P

Figures (11)

  • Figure 1: System model of ARIS-assisted NOMA-HIS communications, where ARIS is capable of amplifying the superposed signals, and then reflecting to users.
  • Figure 2: Outage probability versus the transmit power ${P_b}$, with $K=3$, $g=3$, $f=2$, $L=5$, $\beta=5$, and $m = 0.5$, $R_g=R_f=1.5$ BPCU.
  • Figure 3: Outage probability versus the transmit power ${P_b}$, with $L=5$, $K=3$, $g=3$, $f=2$, $\beta=5$, and $R_g=R_f=1.5$ BPCU.
  • Figure 4: Outage probability versus the transmit power ${P_b}$, with $L=5$, $K=3$, $g=3$, $f=2$, $m=0.5$, $\beta=5$, and $R_g=R_f=1.5$ BPCU.
  • Figure 5: Outage probability versus the different distance between BS and ARIS, with $L=5$, $K=3$, $g=3$, $f=2$, $m=0.5$, $\beta=5$, and $R_g=R_f=1.5$ BPCU.
  • ...and 6 more figures

Theorems & Definitions (30)

  • Theorem 1
  • proof
  • Corollary 1
  • Corollary 2
  • Corollary 3
  • Theorem 2
  • proof
  • Corollary 4
  • Theorem 3
  • Corollary 5
  • ...and 20 more