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A Unified NOMA Framework in Beam-Hopping Satellite Communication Systems

Xuyang Zhang, Xinwei Yue, Tian Li, Zhihao Han, Yafei Wang, Yong Ding, Rongke Liu

TL;DR

This work develops a unified NOMA framework for beam-hopping satellite communications (U-NOMA-BH) that jointly handles code-domain and power-domain NOMA (CD-NOMA-BH and PD-NOMA-BH). By formulating a resource-optimization problem that minimizes the squared gap between achieved rates $R_$ and traffic demands $D_$, the authors optimize beam scheduling, subcarrier assignment, and power factors using relaxation, Dinkelbach's transform, and alternating convex programming. They derive closed-form outage probabilities and diversity orders under imperfect CSI (ipCSI) and perfect CSI (pCSI) and analyze the delay-limited throughput, showing that CD-NOMA-BH offers superior performance and fairness compared with PD-NOMA-BH and OMA-BH. Numerical results demonstrate that U-NOMA-BH reduces the demand-supply gap, improves capacity provisioning, and achieves better outage behavior, especially in non-uniform traffic scenarios and with robust channel estimation. The framework provides a practical, scalable approach to dynamic, multi-user satellite resource management in 6G-era BH systems, with clear pathways for extending to polarization techniques and extended CSI models.

Abstract

This paper investigates the application of a unified non-orthogonal multiple access framework in beam hopping (U-NOMA-BH) based satellite communication systems. More specifically, the proposed U-NOMA-BH framework can be applied to code-domain NOMA based BH (CD-NOMA-BH) and power-domain NOMA based BH (PD-NOMA-BH) systems. To satisfy dynamic-uneven traffic demands, we formulate the optimization problem to minimize the square of discrete difference by jointly optimizing power allocation, carrier assignment and beam scheduling. The non-convexity of the objective function and the constraint condition is solved through Dinkelbach's transform and variable relaxation. As a further development, the closed-from and asymptotic expressions of outage probability are derived for CD/PD-NOMA-BH systems. Based on approximated results, the diversity orders of a pair of users are obtained in detail. In addition, the system throughput of U-NOMA-BH is discussed in delay-limited transmission mode. Numerical results verify that: i) The gap between traffic requests of CD/PD-NOMA-BH systems appears to be more closely compared with orthogonal multiple access based BH (OMA-BH); ii) The CD-NOMA-BH system is capable of providing the enhanced traffic request and capacity provision; and iii) The outage behaviors of CD/PD-NOMA-BH are better than that of OMA-BH.

A Unified NOMA Framework in Beam-Hopping Satellite Communication Systems

TL;DR

This work develops a unified NOMA framework for beam-hopping satellite communications (U-NOMA-BH) that jointly handles code-domain and power-domain NOMA (CD-NOMA-BH and PD-NOMA-BH). By formulating a resource-optimization problem that minimizes the squared gap between achieved rates and traffic demands , the authors optimize beam scheduling, subcarrier assignment, and power factors using relaxation, Dinkelbach's transform, and alternating convex programming. They derive closed-form outage probabilities and diversity orders under imperfect CSI (ipCSI) and perfect CSI (pCSI) and analyze the delay-limited throughput, showing that CD-NOMA-BH offers superior performance and fairness compared with PD-NOMA-BH and OMA-BH. Numerical results demonstrate that U-NOMA-BH reduces the demand-supply gap, improves capacity provisioning, and achieves better outage behavior, especially in non-uniform traffic scenarios and with robust channel estimation. The framework provides a practical, scalable approach to dynamic, multi-user satellite resource management in 6G-era BH systems, with clear pathways for extending to polarization techniques and extended CSI models.

Abstract

This paper investigates the application of a unified non-orthogonal multiple access framework in beam hopping (U-NOMA-BH) based satellite communication systems. More specifically, the proposed U-NOMA-BH framework can be applied to code-domain NOMA based BH (CD-NOMA-BH) and power-domain NOMA based BH (PD-NOMA-BH) systems. To satisfy dynamic-uneven traffic demands, we formulate the optimization problem to minimize the square of discrete difference by jointly optimizing power allocation, carrier assignment and beam scheduling. The non-convexity of the objective function and the constraint condition is solved through Dinkelbach's transform and variable relaxation. As a further development, the closed-from and asymptotic expressions of outage probability are derived for CD/PD-NOMA-BH systems. Based on approximated results, the diversity orders of a pair of users are obtained in detail. In addition, the system throughput of U-NOMA-BH is discussed in delay-limited transmission mode. Numerical results verify that: i) The gap between traffic requests of CD/PD-NOMA-BH systems appears to be more closely compared with orthogonal multiple access based BH (OMA-BH); ii) The CD-NOMA-BH system is capable of providing the enhanced traffic request and capacity provision; and iii) The outage behaviors of CD/PD-NOMA-BH are better than that of OMA-BH.
Paper Structure (17 sections, 10 theorems, 40 equations, 9 figures, 2 tables, 2 algorithms)

This paper contains 17 sections, 10 theorems, 40 equations, 9 figures, 2 tables, 2 algorithms.

Table of Contents

  1. Introduction
  2. Motivation and Contributions
  3. Organization and Notations
  4. System Model
  5. PROBLEM FORMULATION
  6. Problem Formulation
  7. Subcarrier and Power Optimization in Solving $\mathcal{P}_{0}$
  8. Optimization of time slots allocation
  9. Performance Analysis
  10. The Outage Probability of User $n$
  11. The Outage Probability of User $m$
  12. Diversity Order Analyses
  13. Throughput Analyses
  14. NUMERICAL RESULTS
  15. Simulation Results of Optimization
  16. ...and 2 more sections

Key Result

Theorem 1

The closed-form expression for the outage probability of the investigated user n with ipCSI can be expressed as in CD-NOMA-BH system where $\chi=\sqrt{G_{r}} \sqrt{\left(\frac{\lambda}{4 \pi d_{\mathrm{m}}}\right)^{2}} \sqrt{G_{t}}$, ${\Omega _1} = \frac{{{\varepsilon _m}{\omega ^*}}}{{{a_{mt}} - {\varepsilon _m}{a_{nt}}}}$, ${\Omega _2} = \frac{{{\varepsilon _n}{\omega ^*}}}{{{a_{nt}}}}$, ${\tau

Figures (9)

  • Figure 1: An illustration of U-NOMA-BH satellite communication systems.
  • Figure 2: The U-NOMA-BH scheme is compared with the benchmarks in terms of capacity gap.
  • Figure 3: Performance comparison of BCU and BEU based on different timeslots and number of active beams.
  • Figure 4: A research of the achievable capacity of users with three different polarization reuse methods and users traffic requirements.
  • Figure 5: The comparison of objective value performance of CD-NOMA-BH with different carrier conditions.
  • ...and 4 more figures

Theorems & Definitions (16)

  • Theorem 1
  • proof
  • Corollary 1
  • Corollary 2
  • Theorem 2
  • proof
  • Corollary 3
  • Corollary 4
  • Corollary 5
  • Remark 1
  • ...and 6 more