Research On Wireless Channel Measurement And Modeling In Desert Edge

With the constant attention of the state to the economic development of deserts,remarkable economic benefits of deserts are achieved,especially deserts edge.The economic development of deserts has brought out wireless communication industry of deserts,the wireless communication system needs to be completed urgently to ensure that the communication of deserts is quick and convenient.The performance of wireless communication system is mainly restricted by the quality of wireless channel model.The radio wave will meet kinds of obstacles when it propagates from transmitting antenna to receiving antenna,so the wireless channel has randomness.The traditional wireless channel models are mostly aimed at densely populated areas,such as cities,suburbs,rural areas and so on,the research literature on the wireless channel model of deserts edge is very few.For the characteristics of radio wave fading in deserts edge,a combination method of the theory and experiment is adopted to study the link loss of wireless sensor signal transmission in this thesis.In order to acquire the path loss of WSN,the wireless signal strength test system is designed based on CC2530.The system has many more characteristics,such as low cost,low power consumption,small volume,digital display and so on.The strength value of the receiving signal can be measured at any point trough the system.According to the test scheme,the data are acquired in the desert edge.The data are compared with free space model,the ground reflection model,Okumura-Hata model,single-line and double-lines logarithmic distance path loss model.The genetic algorithm is used to optimize the parameter selection of support vector machine,and the method of K value selection in the K-fold cross-validation is improved.A path loss model is established based on the improved GA-SVM.Compared with the other models,the result shows that the GA-SVM model has a better accuracy.Based on the two-ray theory and increasing the curvature factor of the earth,a wireless two-ray model in desert edge environment is established,which provides a basis for the study of the propagation characteristics of radio waves in a large area of desert edge.