## 3 The Results of the Bibliometric Analysis
### Citation and Co-Citation Network Analysis  
#### 3.3.1 Publications Citation and Co-Citation Analysis  
Citation analysis is a way of measuring the influence and quality of a publication by counting the number of times that the publication has been cited by other publications [27]. The retrieved 402 papers were cited 3862 times by 3793 publications from 1270 publication sources. A total of 1881 out of 3793 publications were published by Chinese Institutions, which accounted for 49.60% of the citing publications. On top of that, out of 402 retrieved papers, 112 papers were never cited as of 1 October 2023; 235 papers, over half of the publications, were cited fewer than five times by any other publications. Table 4 presents a compilation of the ten most extensively cited scholarly works in the domain of USV new technology authored by global researchers. Notably, the paper titled \"6G Wireless Communication Systems: Applications, Requirements, Technologies, Challenges, and Research Directions\" by [PERSON] et al. [46], was considered both the most cited publication and the one with the highest average citation count. This article, while focusing on the subject of 6G wireless communication, offered a comprehensive review of research developments pertaining to the application and prospects of 6G and reveals potential cultivation in USVs. The second most frequently cited article, written by [PERSON] et al. [6] and published in 2019, presented a real-time and deterministic path-planning method for USVs in complex and dynamic navigation environments. In this paper, a modified Artificial Potential Field (APF), which contained a new modified repulsion potential field function and the corresponding virtual forces, was developed to address the issue of Collision Avoidance (CA) with dynamic targets and static obstacles, including emergency situations [6]. Additionally, among the recent frequently cited literature, [PERSON] et al. [47] developed and applied algorithms for the central navigation and planning problems on ship hulls to achieve a closed-loop control relative to features such as weld lines and biofuling, thus laying a cornerstone for operations on naval ships. Furthermore, it is worth mentioning that in the top 10 most highly cited publications, 6 of them were concentrated on the path-planning research of USVs, from the objective of collision avoidance to the real-time algorithms, showing tremendous attention from scholars to these aspects. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Article** & **Title** & **TC** & **ACY** \\ \hline [PERSON] et al., 2020 [46] & 6G Wireless Communication Systems: Applications, Requirements, Technologies, Challenges, and Research Directions & 415 & 103.75 \\ [PERSON] et al., 2019 [6] & COLREGS-Constrained Real-time Path Planning for Autonomous & 164 & 32.80 \\  & & & \\  & & & \\  & & & \\  & & & \\  & & & \\ \end{tabular}
\end{table} 
Table 4: Top 10 most highly cited publications on USV. Co-citation, as originally articulated by [PERSON] [55] in 1973, refers to the frequency of instances where two documents are jointly referenced by other scholarly works. Employing co-citation analysis, a valuable method for assessing the resemblance between documents and revealing thematic structures within a research field, publications were organized into distinct clusters, as expounded upon by [PERSON] et al. [27] in 2020. Among the 10,108 references found within the 402 retrieved publications, a mere 1053 references received citations two or more times. Figure 11 presents a graphical representation of the co-citation network, encompassing references that garnered citations exceeding seven occurrences within the retrieved publications of new technology in USV research. To conduct this analysis, VOSviewer was used as a powerful tool. The resultant network comprised 52 references that satisfied this citation frequency criterion. In this depiction, the sizes of the spheres correspond to the frequency of citations that each publication has received.