## 3 The Proposed Detector for Uplink GF-NOMA Networks: FROMPUS
### Node C: Reverse-Select
However, the only downside of the proposed FROMPUS-based MUD is its slightly high computational complexity cost in comparison with some of the detectors considered in this paper. On the other hand, the computational complexity cost can be compromised in situations where the performance of MUD is the main priority, especially at the base station, where the detection process is performed in the context of uplink GF-NOMA wireless communication networks. Based on these results, the proposed detector is a good candidate for 5G and beyond 5G wireless networks with multiple access-based NOMA schemes. In terms of future research directions, the immediate focus will be directed towards the reduction of the computational complexity cost of the proposed FROMPUS-based MUD without compromising its overall performance. Furthermore, the proposed FROMPUS-based MUD will need to be investigated for massive multiple-input multiple-output-NOMA (massive MIMO-NOMA) and millimeter wave-based multiuser wireless communication networks. **Funding:** This research was funded by the National Research Foundation (NRF) of South Africa through both NRF Competitive Program (funding) for Rated Researchers with grant number 118547 and funding based on the NRF, South Africa/NCBR, Poland joint science, and technology research collaboration with grant number 118678. **Data Availability Statement:** Data sharing is not applicable to this article. \begin{table}
\begin{tabular}{c c c} \hline \hline
**MUD Detector** & **Order of Complexity Cost** & **Numerical Results (N = 100, U = 300, \(\Im=\) 20)** \\ \hline Comp Efficient OMP & \(UlogU\) & \(1\,711\) \\ \hline OMP & \(N\Im^{2}\) & 40,000 \\ \hline SOMP & \(NU\Im^{2}\) & 12,000,000 \\ \hline Modified OMP & \(\Im(NU+\Im^{2}N)\) & 1,400,000 \\ \hline Modified SP & \(\Im(NU+\Im^{2}+\Im N)\) & 648,000 \\ \hline FROMPUS & \(\Im(5 NU+\Im(\Im+N+\Im N))\) & 3,848,000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparative computational complexity costs. **Acknowledgments:** The author would like to thank [PERSON] of the School of Computing, University of Eastern Finland who sacrificially read through the manuscript and provided some technical suggestions that have improved the quality of this paper. Special thanks to the handling editor and the anonymous reviewers for their constructive comments. **Conflicts of Interest:** The author declares no conflict of interest. ## Appendix A

In this section, a block diagram illustrating the operations of the proposed FROMPUS-based MUD is presented in Figure A1. As can be seen from the block diagram, the operations of the MUD commence with initialization, which is based on the Fused Modified OMP-Modified SP. Its outputs are transmitted into the \"Forward-Include\" unit of the MUD, which selects the highest amplitude-based element in a bid to select the correct element of the active users support set. Its output is used by the \"Reverse-Select\" unit of the MUD, which simply performs a reliability test. The support set computed by this unit is employed by the FROMPUS to compute the desired active users' transmitted signals. ## References

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