## 4 Implementation
### GPSR_DA Algorithm
#### 4.1.2 Angle Calculation
### Scalability and Practicality

With the evolution of MANETs towards vehicular networks, we need to focus on adapting to the unique environments and application scenarios of vehicular networks, such as high-speed mobility, frequent node connections and disconnections, and fluctuating communication quality. At the same time, considering the high requirements of vehicular networks for communication reliability and real-time performance, more in-depth optimization and research are needed on metrics such as data transmission delays, throughput, and energy efficiency. SD-GPSR has excellent scalability and practicality. From the experiments, we can see that SD-GPSR performs excellently in environments with high-speed node movement. With its location discovery and update mechanisms, as well as location interruption mechanisms, it can effectively handle frequent changes in network topology. Therefore, it shows good performance in addressing challenges such as high node mobility, frequent node connections and disconnects, and fluctuation in communication quality in vehicular networks. Consequently, SD-GPSR can be effectively used in vehicular networks. ## 6 Conclusions

This paper proposes an SD-GPSR routing method that decentralizes some routing functions of SD-MANET to the data plane by utilizing the geographic location information of nodes for routing. Additionally, an improved greedy forwarding algorithm based on distance and angle (GPSR_DA) is introduced, where the controller provides location services and partial centralized decision-making, and data plane nodes use the GPSR_DA algorithm to forward data. This approach enhances the self-organizing capability and overall routing efficiency of the nodes while reducing routing control overhead. To address the potential issue of routing voids during the forwarding process, the \(A^{*}\) algorithm is employed to calculate optimal routing paths that avoid voids. Flow tables are deployed using source routing principles, effectively reduces control overhead. Validation and analysis of the SD-GPSR routing method demonstrate superior performance advantages in terms of control overhead and packet loss rates in large-scale networks. [PERSON] wrote the main manuscript text, including study design, experiments and data analysis. [PERSON] provided computational resources and critically commented on the revised manuscript. [PERSON] prepared the figures and completed and checked the English grammar and [PERSON] revised the manuscript. All authors have read and agreed to the published version of the manuscript. This research received no external funding

The data supporting this article are from previously reported studies and datasets, which have been cited. The authors express their gratitude to the editor and reviewers for their work and valuable comments on the article. ## References

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