## 4 Algorithm Description
### The Network Operation Process
Service 1 has a relatively median delay value due to its equal emphasis on delay and packet loss rate. The above analysis results generally highlight the advantages of static configuration. Moreover, as the arrival rate increases, the queuing delay will continue to increase, leading to an increase in end-to-end delay. ### Throughput

Figure 12 shows the comparison of throughput values for different schemes. It is clear from Figure 12 that the proposed algorithm achieves better throughput values than the AODV routing protocols. Service 1 and Service 3 have the highest throughput because their packet loss rate values are relatively moderate, and the delay values are lower. The throughput value of Service 2 lies between Services 1 and 3 and the AODV routing protocol because its packet loss rate value is relatively small compared to Services 1 and 3, and its delay is larger than Services 1 and 3. The AODV routing protocol has the smallest throughput because of its high packet loss rate and large delay, so the average rate of packets successfully arriving at the destination node from the source node is low. After the above analysis, this algorithm can improve the throughput of the system. \begin{table}
\begin{tabular}{c c} \hline \hline
**Curve** & **Value** \\ \hline AODV (red curve) & 0.0834 \\ Service 1 (blue curve) & 0.0654 \\ Service 2 (green curve) & 0.0610 \\ Service 3 (pink curve) & 0.0671 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Average packet loss rate. Figure 10: Packet delivery rate comparison of different rounds. Overall, according to the description above, the distance between the source node and the destination node during the train's journey from one end to the other will first increase and then decrease, and the packet delivery rate and end-to-end delay will also show this trend. Throughput represents the volume of data that is delivered to the destination within each time unit, so it will also show a trend of decreasing first and then increasing. ## 6 Conclusions

Starting from the wireless communication requirements of urban rail transit, this paper studies routing strategies with low latency and high reliability in rail transit scenarios and proposes DASC from the perspective of route updates. This algorithm utilizes an improved

Figure 11: End-to-end delay comparison of different lambda. Figure 12: Throughput comparison of different locations. AODV routing discovery algorithm, selects fixed nodes with a high residual link lifetime to communicate with the train after clustering, and writes the routing table to the router in advance to eliminate the delay caused by routing discovery. The link status of each link is dynamically monitored through detection packets, avoiding the loss caused by replacing the link after the link has been broken during real-time communication. On this basis, different update paths are selected based on the type of communication service. Finally, compared with traditional AODV protocols, simulation results are obtained, verifying the improvement of the proposed algorithm. Compared with traditional AODV, the DASA could reduce the routing discovery overhead by 95% at most, improve the packet delivery rate by 4.6% at most, improve the throughput by 50% at most, and lower the average end-to-end delay by 57% at most. Conceptualization, L.L. ; Methodology, Z.S. ; Software, Z.G. ; Validation, S.C.; Investigation, L.S. ; Resources, H.H. ; Writing--original draft, Z.H. All authors have read and agreed to the published version of the manuscript. This research was supported by the Beijing Natural Science Foundation under the grant of [L211002]. Since the data in this paper will continue to be used in the future, participants of this study did not allow data to be publicly shared. The paper was completed entirely by the listed authors and was approved by all authors for publication. Anyone else who contributed to the manuscript but does not qualify for authorship has been acknowledged with their permission.