Research On Wireless Channel Measurement And Modeling Methods

With the rapid development of mobile communication network convergence and mobile Internet applications,the relevant new technologies and new applications becomes a major research content in the field of wireless communication.Under the new scenario,due to the multipath propagation and time variation,the wireless channel has a huge impact on the performance of wireless communication system.Therefore,measurement and modeling of wireless channel is of great guiding significance for the research of transmission technology.In this paper,measurement and modeling methods of wireless channel are studied based on the propagation characteristics of wireless channel.The main contents are as follows:Firstly,it briefly reviews the propagation characteristics of wireless channel,including large-scale propagation characteristics and the and small-scale propagation characteristics.Then the basic principle of measurement and modeling for wireless channel is introduced,as well as an overview of existing methods.In order to present the practical significance of channel modeling,the paper gives an application case in the field of radio navigation frequency planning.The simulation shows that the results matches well with the FAA standard,and provides a simple and effective method for frequency assignment.Secondly,the large-scale fading channel modeling method is studied in this paper,and the classical large-scale fading modeling using least squares is described in detail.The main work in this part is focused on the channel modeling method of ray tracing,which is based on the deterministic environmental terrain,and the estimated results of a typical scenario is shown with propagation prediction models supported by WinProp.It turned out ray tracing modeling method can adaptively track the specific propagation environment and achieve higher accuracy.Similarly,this paper studies the small-scale fading channel modeling method also,and introduces the characteristic description and tap delay line model of small-scale fading channel.Then the methods of multipath channel estimation,including deconvolution algorithm,spread spectrum sliding correlation method and compressed sensing,are studied.Their principles are described and the simulation analysis under specific conditions is presented respectively.In particular,deconvolution algorithm’ validity is independent of detecting waveforms,i.e.original channel can be estimated by any pulses.However,the shape of detecting pulse affect the estimated performance: the more likely to ideal impulse,the higher performance can be achieved;spread spectrum sliding correlation method has good anti-noise performance and can estimate multipath channel well.Compared with other PN sequences,because of its simplicity and excellent autocorrelation,m sequence is the mostly commonly used;Compressed sensing algorithm makes full use of the sparsity of the wireless channel,and can realize accurate channel estimation under certain conditions.The OMP algorithm has low complexity and satisfactory reconstruction performance,so it is applied widely in many fields.With its excellent estimation performance and flexible configuration,spread spectrum sliding correlation method is the most prevailing on multipath channel estimation.Finally,from the theory to practice,we use the existing instruments and devices of laboratory to conduct a measurement campaign under the campus scenario.The paper describes design scheme of measurement system and parameters extraction method in detail,and corresponding channel impulse response samples are obtained by the spread spectrum sliding correlation method.Through channel modeling,it present statistical characterization of the measured channel.The results suggest that the constructed large-scale fading model is very close to the prediction results of ray tracing-based models;and owing to the openness of the measured scenario,the root mean square delay spread of small-scale fading model is relatively small.