Modeling Of Nakagami-K Composite Channel In Urban-rural Areas

In the process of transmission, radio waves will meet occlusion, absorption, reflection, diffraction and scattering from kinds of obstacles. With the comprehensive analysis of factors which influence the spread of radio waves in the research on transmission characteristics of wireless channels, accurate and reasonable wireless channel models are built to give guidance to improve and enhance communication performance from the aspects of technical approaches and engineering approaches.There are more and more places with typical features of urban-rural areas because of the acceleration of urbanization in China. Irregular arrangements of buildings and disorder of residential areas, factory and farmlands contributes to changeable and complex wireless communication environment. Based on the practical need of the load control and electricity information acquisition by power wireless communication network in urban-rural areas, this paper builds a composite channel model based on Nakagami distribution and K distribution aiming at guiding the communication network planning and systematic design in urban-rural areas and the main contents are as following:â‘  Introducing the typical characteristics and classification of wireless channel models and the differences between large scale fading and small scale fading; analyzing typical channel models which describe shadowing fading and small scale fading, the probability distribution models obey and their model summary; analyzing basic features of Rayleigh-Lognormal channel model on account of composite fading channel model; illustrating two important issues that represent characters of channel fading; the definition and significance of level crossing rate and average fade duration.â‘¡ Analyzing the probability density function of Nakagami distribution and the relationship among Nakagami distribution, Rayleigh distribution and Rician distribution, and the expressions of level crossing rate and average fading durations are derived respectively. Besides, verifying the effectiveness that Nakagami model describes the environment of fast fading channels by fitting theoretical CDF curves of Nakagami distribution and Rayleigh distribution and testing data; elaborating the probability density function and change characteristics of K distribution channel model and the relationship among K distribution channel model, Rayleigh distribution and Gamma distribution, and the expressions of level crossing rate and average fading durations are derived respectively. Moreover, verifying the effectiveness that K distribution channel model describes the environment of slow fading channels by fitting theoretical CDF curves of K distribution and Gamma distribution.â‘¢ According to the characteristics of the urban and rural areas, Nakagami-K composite channel model is used to describe the envelope changes of received signal, of which probability density function is derived, and method of moment is adopted to estimate relevant parameters. Based on experimental data, the effectiveness and accuracy of the model is verified under the circumstances of cities, rural and urban-rural areas. Finally, simulation analysis is made to show the impact variable parameter leaves on level crossing rate and average fading durations.Nakagami-K composite channel model designed in this paper has already been used to plan and predict the radio coverage of an ongoing wireless private network of State grid, Chongqing branch. The implemented part of the project has verified the validity and rationality of the model.