Study On Data Transmission Characteristics Of Wireless Sensor Network For Agricultural Greenhouses

Agricultural greenhouses have a complex condition in which the cultivated plants and the frequent walking of the staff can bring a significant shadow fading to the transmission of the radio singals and at the same time, the number of the plants which need to be monitored is so large that many sensor nodes are required, which leads to a large scale of WSN. A high and strict standard of the network service quality of the agricultural greenhouse monitoring system based on WSN is put forward for the instantaneity, reliability and energy consumption of the network. Moreover, the routing protocol is the decisive one of those factors affecting the data transmission quality, therefore it is important for the production of agricultural greenhouses to design a high-performance routing protocol meeting the monitoring demands of the agricultural greenhouse.First of all, the structure and development status of WSN is analyzed, and for the mission requirements and characteristics of agricultural greenhouses WSN monitoring system, the overall framework of the monitoring system is put forward, and agricultural greenhouses WSN monitoring system is constructed.Secondly, WSN monitoring system above is used to measure the data transmission characteristics and path loss characteristics of the 2.4GHz radio frequency signal under the circumstances of corridor and agricultural greenhouse in the field. Due to the interference brought by the plants shielding and people walking in the agricultural greenhouse environment, Kalman filter is introduced to reduce noise of the original measurement data and then the noise-reduced data is imported into MATLAB to proceed linear fitting analysis and modeling. Through the analysis of the WSN channel propagation model under two different circumstances and experimental phenomena when testing the WSN monitoring system, the performance deficiencies of the WSN monitoring system is found to provide the theoretical basis of perfecting the agricultural greenhouse WSN monitoring system.Finally, aiming at the performance deficiencies mentioned above belonging to Agricultural Greenhouse Wireless Sensor Network Monitoring System, a new ant colony algorithm collection tree routing protocol ACA-CTP is submitted, which takes advantage of the characteristics that the ant colony can find the optimal path from the nest to the food source. The algorithm takes three Qo S indexes which are ant pheromones, node link quality and packet delay as algorithm optimization factors to improve the path probability selection strategy of Ant Colony Algorithm, combines the improved Ant Colony Algorithm with Collection Tree Protocol and is implemented by using nes C language in Tiny OS system. ACA-CTP Routing Protocol select the optimal routing path between the source and destination nodes to ensure the monitoring data an accurate and real-time transmission through the global optimization ability and fast convergence of the improved Ant Colony Algorithm. The simulation results from TOSSIM simulator show that ACA-CTP algorithm extends the network lifetime and reduces the packet transmission delay and packet loss rate.