# Topology Control of Low-Connection UAV Laser Network with Virtual Nodes
## 7 Conclusions  
This paper addresses the issue of network topology control in UAV laser communication networks by proposing a novel algorithm--the VNTC algorithm. The VNTC algorithm is designed to tackle the upper node degree limit caused by the limited power and payload capacity of UAVs, aiming to construct an efficient, stable communication network structure that aligns with the characteristics of laser communication.  
Through the analysis of the UAV laser network model, it was found that, under the condition where each node is equipped with only four laser communication modules, the traditional topology control algorithms struggle to meet the requirements. To address this, the VNTC algorithm employs node pairing and the construction of virtual nodes to reduce the upper node degree limit while ensuring network connectivity. The theoretical foundation and derivation process of the algorithm demonstrate that, under certain radius  
\begin{table}
\begin{tabular}{l c c c} \hline
**Statistical Items** & **Original** & **XTC** & **VNTC** \\ \hline Number of graphs with maximum & 2000 & 127 & 0 \\ node degree greater than 4 & & & \\ \hline Average node degree & 34.42 & 2.51 & 2.27 \\ \hline Maximum node degree & 72 & 5 & 4 \\ \hline Longest shortest path (average distance) & 29.27 & 36.51 & 44.44 \\ for any node & & & \\ \hline Longest shortest path (average jumps) & 15.91 & 68.91 & 78.53 \\ for any node & & & \\ \hline Average shortest distance & 11.15 & 14.14 & 17.35 \\ \hline Average minimum jumps & 6.3 & 26.88 & 30.65 \\ \hline Average number of edges & 20,649.27 & 1503.32 & 1362.57 \\ \hline \end{tabular}
\end{table}
Table 1: Comparison of algorithm performance.  
Figure 12: Topology control diagram generated by the VNTC algorithm.  
conditions, if the graph remains connected, it can ensure that any node has no more than four neighboring nodes. Furthermore, in response to potential unmatched nodes and the planarity of the topology graph, this paper proposes corresponding strategies to further optimize the network structure, enhancing the practicality and flexibility of the algorithm.  
The experimental results indicate that, compared to the XTC algorithm, the VNTC algorithm effectively reduces the upper node degree limit and the number of edges while maintaining network connectivity, enhancing the sparsity of the network, and ensuring to some extent the planarity of the topology graph. This not only validates the effectiveness of the VNTC algorithm but also provides a new solution for topology control in UAV laser communication networks.  
The research presented in this paper still has certain limitations, such as the efficiency and performance of the algorithm when dealing with large-scale networks, as well as its adaptability in dynamically changing environments, requiring further research and exploration.  
Conceptualization, J.Y. and Q.L.; methodology, P.W.; writing--original draft preparation, P.W.; writing--review and editing, Q.L. and J.Y. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding  
Not applicable.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
The authors declare no conflict of interest.