# RIS-Assisted Fixed NOMA: Outage Probability Analysis and Transmit Power Optimization

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## Abstract

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## 1. Introduction

## 2. Related Work

- Analytical outage probability expressions are developed for NU and FU in a RIS-SR-FNOMA and RIS-AP-FNOMA.
- Analytical expressions are developed for optimal power assignment to NU and FU in both RIS-SR-FNOMA and RIS-AP-FNOMA systems.
- Extensive MC simulations are used to corroborate the resulting analytical outage expressions. The accuracy of derived analytical expressions is proved using the strong correlation between the theoretical and simulation results.

## 3. Outage Probability Analysis of RIS-SR-FNOMA

## 4. Outage Probability Analysis of RIS-AP-FNOMA

## 5. Transmit Power Optimization for Sum Capacity Maximization

## 6. Simulations and Discussion

## 7. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## Abbreviations

5G | Fifth-Generation |

6G | Sixth-Generation |

AP | Access Point |

AWGN | Additive White Gaussian Noise |

BS | Base Station |

CSI | Channel State Information |

EM | Electro-Magnetic |

FNOMA | Fixed NOMA |

FU | Far User |

LoS | Line-of-Sight |

MIMO | Multiple Input-Multiple Output |

MC | Monte Carlo |

NOMA | Non-Orthogonal Multiple Access |

NU | Near User |

OMA | Orthogonal Multiple Access |

RF | Radio Frequency |

RIS | Reconfigurable Intelligent Surface |

SIC | Successive Interference Cancellation |

SINR | Signal-to-Interference plus Noise Ratio |

SNR | Signal-to-Noise Ratio |

SR | Smart Reflector |

UAV | Unmanned Aerial Vehicle |

UE | User Equipment |

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**Figure 6.**Sum capacity (b/s/Hz) of RIS-SR-FNOMA for optimal and sub-optimal power assignments and varying N.

**Figure 10.**Sum capacity (b/s/Hz) of RIS-AP-FNOMA for optimal and sub-optimal power assignments and varying N.

**Figure 11.**Sum capacity (b/s/Hz) comparison of FNOMA, RIS-SR-FNOMA and RIS-AP-FNOMA for optimal and sub-optimal power assignments.

Parameter | Typical Value |
---|---|

Number of RIS components $\left(N\right)$ | 32, 64, 128, 256 |

Number of users | 2 |

Mean channel gain of NU | 5 |

Mean channel gain of FU | 1 |

Desired rate of NU ${(\tilde{R}}_{NU})$ | 1 b/s/Hz |

Desired rate of FU ${(\tilde{R}}_{FU})$ | 1 b/s/Hz |

Target outage probability | ${10}^{-4}$ |

Block length | ${10}^{5}$ |

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**MDPI and ACS Style**

Kumaravelu, V.B.; Imoize, A.L.; Soria, F.R.C.; Velmurugan, P.G.S.; Thiruvengadam, S.J.; Do, D.-T.; Murugadass, A.
RIS-Assisted Fixed NOMA: Outage Probability Analysis and Transmit Power Optimization. *Future Internet* **2023**, *15*, 249.
https://doi.org/10.3390/fi15080249

**AMA Style**

Kumaravelu VB, Imoize AL, Soria FRC, Velmurugan PGS, Thiruvengadam SJ, Do D-T, Murugadass A.
RIS-Assisted Fixed NOMA: Outage Probability Analysis and Transmit Power Optimization. *Future Internet*. 2023; 15(8):249.
https://doi.org/10.3390/fi15080249

**Chicago/Turabian Style**

Kumaravelu, Vinoth Babu, Agbotiname Lucky Imoize, Francisco R. Castillo Soria, Periyakarupan Gurusamy Sivabalan Velmurugan, Sundarrajan Jayaraman Thiruvengadam, Dinh-Thuan Do, and Arthi Murugadass.
2023. "RIS-Assisted Fixed NOMA: Outage Probability Analysis and Transmit Power Optimization" *Future Internet* 15, no. 8: 249.
https://doi.org/10.3390/fi15080249