# Review of Physical Layer Security in 5G Wireless Networks
## 2 Methodology  
The research methodology for this study on physical layer security in 5G wireless networks followed a systematic review approach using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology. During the identification stage, the Google Scholar database was searched using the inclusion and exclusion criteria in Table 1. The papers that were included were those that focus on physical layer security in 5G networks and were published between 2014 and 2023 in academic journals or conference proceedings, which were listed as the source type.  
This review article aims to analyze the current state of research on physical layer security in 5G wireless networks. Papers that were excluded were those of studies that do not focus on the physical layer; studies that focus on other layers of the 5G network or on other wireless networks; studies that are not related to security, vulnerabilities, or threats in  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Inclusion Criteria** & **Exclusion Criteria** \\ \hline Studies that focus on physical layer security in & Studies that do not focus on the physical layer \\
5G wireless networks. & security in 5G wireless networks. \\ \hline Studies that investigate security issues, & Studies that focus on other layers of the 5G \\ vulnerabilities, and threats in the physical layer & network or on other wireless networks. \\ of 5G wireless networks. & Studies that are not related to security, \\ \hline Studies that propose or evaluate physical layer & Studies that are not related to security, \\ security solutions or mechanisms for 5G & vulnerabilities, or threats in the physical layer \\ wireless networks. & of 5G wireless networks. \\ \hline Studies that are published in peer-reviewed & Studies that do not propose or evaluate \\ journals or conference proceedings. & physical layer security solutions or \\ mechanisms for 5G wireless networks. \\ \hline \hline \end{tabular}
\end{table}
Table 1: Inclusion and exclusion criteria.  
the physical layer of 5G wireless networks; studies that do not propose or evaluate physical layer security solutions or mechanisms for 5G wireless networks; studies that were not written in English. Furthermore, some documents were not available online. The Figure 1 explains the PRISMA methodology. The PRISMA flowchart was used to guide the selection of articles [2]. The PRISMA flow diagram passes through four stages. The identification stage is when items are identified for review, and during this stage, the papers were identified from Google Scholar. The screening stage is when the papers are screened and selected for review. The eligibility stage is when the papers are eligible to be included [7]. The inclusion stage yields a list of studies to be included in the systematic review. Figure 1 shows that 3500 articles were selected during the identification stage after using the search string (\"psychical layer security\" OR \"5G security\"). At first, 2626 articles were rejected because of exclusion criteria. At the screening stage, 874 articles were reviewed for title and abstract, and all but 252 were rejected. Next, out of the 252 articles, only 89 were accepted due to the exclusion criteria at the eligibility stage because they did not closely fulfill the requirements, leaving only 45 articles to be included in the review.