Research On Spectrum Sensing Strategy Of Agricultural Internet Of Things Based On Cognitive Radio

Agriculture is the foundation of China's national economy.In recent years,with the popularization and development of agricultural modernization,the agricultural Internet of Things has been developed rapidly.In the agricultural Internet of Things,a large number of sensing nodes and terminals need to transmit the collected agricultural information to the data center for reference and analysis by farmers and agricultural experts.However,with the explosive growth of Internet of things services and data transmission in agriculture Internet of Things,the traditional communication technology and the current fixed spectrum resource allocation strategy have been unable to meet the need of massive data transmission.The lack of wireless spectrum has become the bottleneck of the development of agricultural Internet of Things.Cognitive radio provides an effective way to solve the shortage problem of spectrum resources.It can realize dynamic spectrum allocation and management by spectrum sensing,dynamic spectrum allocation and spectrum sharing without interference to the normal communication of the primary user.So it can effectively improve the spectrum utilization.In this paper,cognitive radio is introduced in agriculture Internet of things.In order to solve the problem of spectrum resource shortage in agricultural Internet of Things,considering the particularity of agricultural Internet of Things environment,spectrum sensing technology of cognitive radio is used to sense multiple heterogeneous channels in the agricultural Internet of Things fast and effectively.The main research of this paper are as follows:(1)According to the network structure and characteristics of the agricultural Internet of Things,considering the different network types and bandwidths in the agricultural Internet of Things,two implementation schemes of cognitive agricultural Internet of Things are proposed.They provide a realistic scene model for the implementation of the spectrum sensing strategy of the agricultural Internet of Things in the future.(2)Aiming at the problem of different cognitive users' different sensing performance for heterogeneous channels in the cognitive agricultural Internet of Things,ZigBee,RFID,Bluetooth and WiFi wireless communication technologies are selected in this chapter to transmite data between nodes.A spectrum sensing strategy based on step-by-step satisfaction is proposed for heterogeneous multi channels in the agricultural Internet of Things.It solves the problem that how multiple cognitive users sense multiple channels simultaneously in the agricultural Internet of Things.The spectrum sensing strategy based on the step-by-step satisfaction algorithm is compared with the spectrum sensing methods based on genetic algorithm and iterative Hungarian algorithm.The simulation results show that,for the proposed strategy based on the step-by-step satisfaction algorithm,it needs less cooperative cognitive users who partcipate spectrum sensing and can obtain higher effective throughput.(3)Energy consumption is a important issue in the agricultural Internet of Things,and sensing time is one of the key factors that affect the energy consumption of the system.In order to improve energy efficiency and balance the relationship between sensing time,effective throughput and system energy consumption in the process of spectrum sensing,an energy efficiency model of spectrum sensing is established in this chapter.A cross layer spectrum sensing strategy based on genetic algorithm is proposed for heterogeneous channels in agricultural Internet of Things.The simulation results show that,compared with the random algorithm,the proposed spectrum sensing strategy based on genetic algorithm can optimally determine the task assignment and the sensing time to maximize the system energy efficiency.In conclusion,to solve the prolem of the combination of cognitive radio and agricultural Internet of Things in the practical application,firstly,two implementation schemes of cognitive agricultural Internet of Things are proposed,which provide solutions for its specific implementation.To adress the issue of the shortage of spectrum resources in the agricultural Internet of Things,two spectrum sensing strategys of the cognitive agricultural Internet of Things are proposed to solve the problem that how multiple users cooperatively sense multiple heterogeneous channels.They improve the utilization rate of spectrum resources in agricultural Internet of Things,solve the problem of the urgent shortage of spectrum resources in the agricultural Internet of Things,and provide theoretical support and foreshadowing for the future development of the cognitive agricultural Internet of Things.