Research On Key Technologies Of Low Energy Consumption And Reliable Transmission In Farmland Wireless Sensor Network

Wireless sensor network(WSN)provides real time monitoring of environment,soil and crops.It is very useful for precision agriculture operation such as water and fertilizer application,pest diagnosis,expert guidance and decision-making.It also has important contribution to the rational use of agricultural resources,reducing production costs,improving the yield and quality of agricultural products.Farmland WSN has the characteristics such as wide distribution area,long continuous monitoring cycle and limited resources like bandwidth and energy.In particular,the terrain fluctuation and crop growth change in the farmland environment have a strong impact on the wireless signal propagation.Complex wirelss signal channel require a higher performance of network transmission.Low energy consumption and reliability are important indicators to evaluate the performance of wireless sensor networks.This paper studies the key technologies of low-energy and reliable transmission methods of farmland wireless sensor networks.Wheat farmland is taking as the application environment.The impact of farmland complex dynamic gradient environment on wireless signal,such as link quality,transmission reliability and node energy consumption were analyzed.A large number of wireless signal transmission data of wheat farmland was obtained through the farmland experiment.The channel model of farmland environment was established.Link prediction,topology balance control,low energy consumption and reliable transmission were studied in this work.It provides a useful reference for realizing stable and reliable monitoring and intelligent fine management of precision agricultural production.The main research contents and innovations of this paper contain the following four aspects:(1)Crop growth associated channel model of farmland environment.The experiment of wireless signal propagation in wheat farmland was carried out.And a large number of wireless signal fading and communication quality data was obtained under different growth stages and crop density.The quantitative relationship between crop occlusion and wireless signal propagation was proved.A multi-scale modeling method based on occlusion clearance is proposed.The classical logarithmic model was used under the condition of no occlusion.A novel small-scale probability model was proposed under the condition of dense occlusion and non line of sight(NLOS)propagation.The environmental correlation parameters and signal quality were taken into consideration during the channel modeling.The influence of multi-scale effect on signal strength was effectively explained by the proposed model.The accuracy of the model was significantly improved,which solves the problem of low accuracy of the model in multipath NLOS propagation by traditional methods.It provides a model basis for low energy and reliable transmission optimization in farmland environment.(2)Topology game equilibrium strategy based on link quality estimation.The farmland multipath environment makes the network topology changing dynamicly.This leads to an unstable state of network link.How to organize and adaptively adjust the network topology effectively is the most important influencing factor in network transmission.A link quality estimation method was proposed.based on farmland channel model.A new network connectivity coverage criterion was defined.The network physical topology enhancement method was designed,and the topology equilibrium control strategy was proposed based on ordered potential game theory.A novel node benefit function was established according to the residual energy estimation,transmission distance and link quality.The Nash equilibrium point was found by game iterative convergence of the strategy under the constraints of network node degree and average transmition power.It realizes the maximization of network utility under the condition of dynamic change of network topology,and provides the topological structure basis for the optimization of network transmission performance.(3)Energy aware routing optimization algorithm for farmland wireless sensor networks.Traditional method always selects cluster heads first and then clustering according to distance.This paper proposed a novel non-uniform clustering algorithm based on the similarity between nodes,according to the irregular link quality caused by the influence of multipath fading in farmland environment.The proposed method designed an effective energy consumption estimation of two hop nodes.Improved particle swarm algorithm is used in path selection between cluster heads.A new fitness function was constructed according to the path residual energy,hops and link quality.The initialization method of data transmission path reverse detection was designed,in order to simplify the path selection.It realizes the energy efficient utilization of wireless sensor network data collection in the complex environment of wheat farmland.(4)Energy cost estimation based simultaneous interpreting mechanism.In order to improve the transmission reliability under dense shelter,a simultaneous interpreting concept of wireless signal multicast is introduced.A method of opportunistic relay cost estimation based on channel and energy consumption is proposed.The relationship between opportunistic forwarding connectivity probability and data transmission energy consumption was analyzed,and the link quality,expected single hop energy consumption and node residual energy were comprehensively weighted.An opportunity balanced transmission model integrating the characteristics of network residual energy,path dynamic loss and differential connectivity density was established.The efficiency of opportunistic relay forwarding was improved by preferentially selecting nodes with low path energy consumption,high residual energy and good link quality for opportunistic forwarding.While maintaining high transmission reliability,it solves the problems of large monitoring overhead and unbalanced node energy consumption in traditional opportunistic routing.It provides a feasible scheme for long-term reliable transmission of farmland wireless sensor networks under severe occlusion.This study provides a certain reference value for improving the adaptability of wireless sensor network technology under the condition of farmland complex multipath channel and realizing long-term stable and reliable monitoring transmission.At the same time,it also provides some theoretical support for the comprehensive perception interaction,high dynamic network self-organization,wide width and low delay transmission optimization required for precision agriculture management,such as crop growth identification and variable fertilizer and drug application.