# An Efficient Opportunistic Routing Protocol with Low Latency for Farm Wireless Sensor Networks
## 6 Conclusions  
Focusing on the actual demand of precision agriculture for wireless sensors, this paper studies an energy-saving opportunistic routing transmission protocol for farm WSN. This paper introduces algebraic connectivity to establish an importance model. On this  
Figure 11: Retransmission rate under a different number of nodes.  
Figure 10: Box graph of RR.  
Figure 9: Retransmission rate difference.  
basis, combined with energy consumption, a transmission cost model combining anycast transmission cost and candidate set path cost is designed. Then, we improved the Bellman-Ford algorithm to calculate the minimum expected transmission cost. The backoff time is studied to sort the forwarding nodes and reduce the number of invalid copies in the network. The simulation experiment results show that the opportunistic routing algorithm studied in this paper has obvious advantages in energy efficiency, throughput, network delay, and packet delivery rate.  
Focusing on the actual demand of precision agriculture for wireless sensors, this paper studies an energy-saving opportunistic routing transmission protocol for farm WSN. Opportunistic routing makes use of the characteristics of network broadcast and selects candidate forwarding sets for data transmission to ensure reliable data transmission when links are unstable and connected in the complex environment of the farm. The node importance model is designed based on algebraic connectivity. Combined with energy balance, link interaction, and energy consumption, the opportunistic transmission cost function is constructed. The Bellman-Ford algorithm is improved to calculate the expected minimum transmission cost. Considering the factors of data transmission and network demand, a node forwarding strategy based on backoff time is developed, which can reduce the number of copies in the network while selecting the only forwarding node, and further reduce the network energy consumption. Compared with the comparison algorithms, this algorithm can reduce the energy consumption speed of important nodes and construct a more appropriate candidate set according to the link interaction. Simulation results show that this algorithm can improve packet delivery rate and throughput while limiting network overhead and reducing transmission delay.  
This paper mainly studies the opportunistic routing transmission mechanism of static nodes in the farm, but the farm WSN also includes mobile sensing nodes such as UAVs and tractors. Therefore, our further research will mainly focus on the data machine transmission mechanism in the hybrid network where mobile nodes and static nodes exist at the same time.  
Conceptualization, H.W. and X.H.; literature search, figures, table X.H., C.C. and B.Y.; methodology, H.W. and H.Z.; validation, H.Z. and X.H.; formal analysis, X.H., H.Z. and C.C.; writing--original draft preparation, all authors; funding acquisition, H.W. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China, grant number 61871041, and China Agriculture Research System of MOF and MARA, grant number CARS-23-D07. The authors declare no conflict of interest.