# Adaptive Power-Controlled Depth-Based Routing Protocol for Underwater Wireless Sensor Networks
## 5 Conclusions and Future Work  
To address the issues of high energy consumption and short network lifetime in underwater sensor networks, this paper proposed an adaptive power-controlled depth-based routing protocol (APCDBRP). In terms of power control, the protocol estimates the path loss based on the received signal strength and adjusts the transmission power accordingly. In the selection of the next hop, the forwarding factor takes into account various factors such as the transmission power, depth difference, and remaining energy to optimize energy efficiency and energy balance. It selects the next hop node with high energy efficiency and relatively sufficient energy. In order to cope with the mobility of nodes caused by water flow, we adopted an implicit routing update mechanism during the data forwarding phase to address network topology changes resulting from node mobility at a low cost. Additionally, we proposed a data protection and route reconstruction mechanism to handle potential data forwarding failures and routing voids that may occur due to network topology changes.  
Simulation results demonstrated that APCDBRP outperforms existing typical protocols in terms of network lifespan, energy consumption, and packet delivery ratio. However, it is worth noting that the power control and data protection mechanisms of APCDBRP introduce a certain end-to-end delay. Therefore, APCDBRP is suitable for systems that are not sensitive to latency but require a long network lifespan, such as underwater pollution monitoring and device monitoring applications with lower real-time requirements.  
The current research on routing protocols for underwater wireless sensor networks has made some progress, but further studies still need to be carried out and further improved  
Figure 16: Influence of the node speed on the average end-to-end delay.  
Figure 17: Influence of the node speed on the total energy consumption.  
due to the limitations of time, funds, and experimental conditions. For the continued research on underwater acoustic sensor networks, we believe that there are still new areas to be explored. For example, with the development of devices, underwater nodes have gradually gained the ability to harvest energy underwater, so the protocol design needs to consider the energy allocation problem of nodes with certain charging capabilities.  
Conceptualization, H.Z.; methodology, H.Z. and B.W.; software, H.Z.; validation, H.Z., B.W. and Y.Z.; formal analysis, B.C.; investigation, X.G.; resources, Y.Z.; data curation, B.W.; writing--original draft preparation, H.Z.; writing--review and editing, B.W., Y.Z. and B.C.; visualization, H.Z.; supervision, B.W.; project administration, Y.Z.; funding acquisition, B.W. All authors have read and agreed to the published version of the manuscript.  
This work was supported in part by the National Natural Science Foundation of China under Grant 52071164 and in part by the Postgraduate Research and Practice Innovation Program of Jiangsu Province under Grant KYCX22_3844.  
The data presented in this paper are available upon contacting the corresponding author.  
The authors would like to thank the anonymous reviewers for their careful reading and valuable comments.  
The authors declare no conflict of interest.