Research On Wireless Communication Channel Modeling And Physical Layer Security Transmission Application

The rapid development of the economy and society has promoted the optimization and upgrading of the wireless communication system.The requirements of people for the quality of communication services are increasing,and the pursuit of the speed of data transmission is increasing,and the requirements for scenes are more and more diverse.These make the wireless communication system not only to continue to improve the rate of data transmission,but also to provide a good guarantee for the security of all kinds of communication scenes and the quality of communication.In wireless communication systems,as a physical medium between transceiver in wireless communication systems,the characteristics of the wireless channel determine the performance of the wireless communication system,such as the bit error rate,correlation,and so on.It is a vital part of the wireless communication system.As the electromagnetic wave will experience reflection,scattering and diffraction during the transmission process,it is affected by various obstacles and the motion of the transceiver.In order to meet people's demand for communication quality,the premise of optimizing and upgrading of the wireless communication system is to study the modeling and estimation of channel characteristics.At the same time,because of the rapid development of the economy and society,the demand for the quality of communication services is increasing,the pursuit of the speed of data transmission is increasing,and the requirements for the security of the scene are becoming higher and higher.In this context,physical layer secure transmission has become a research hotspot in the field of wireless communication in recent years.In geometric channel modeling,the diversity of geometric models improves the difficulty of research.Therefore,we study the distribution of Von Mise Fisher(VMF)in the context of three-dimensional sphere channel model.This distribution represents a large class of directional geometric feature distributions,and VMF distribution can be used to fit specific distributions.Thus,a unified distribution model is applied to simulate a large class of geometric features,which simplifies the channel modeling and analysis in engineering applications.On this basis,the ideal baseband signal module and geometric modeling fading channel module are designed in the Agilent ADS software,and the required baseband fading signals is generated by the ideal baseband signal through the fading channel module.The validity of the design is confirmed by the MATLAB software and testing with spectrum analyzer,respectively.Channel parameter estimation is a prerequisite for many communication modules,in which the Doppler extension and signal to noise ratio characterizing the characteristics of time-varying channels.It has important value for adaptive communication and handover applications.Based on the analysis of the traditional level passing rate(level crossing rate,LCR),the error of Double sampling rate joint Doppler extension(double sampling rate,DSR)and signal to noise ratio estimation is analyzed and simulated.The influence of sampling rate selection on estimation performance is found.And the optimal sampling rate under the setting of system simulation is obtained.The simulation shows that the optimized estimator has excellent performance.The SCM (Spatial Channel Model)is a universal model in the current and even in the future mobile communications,and it is also a channel model used in many physical layer security researchs.But in the past,secret key methods of physical layer security usually assume the channel reciprocity under time division duplex(time division duplex,TDD).However,our research shows that the coefficients of strict time-varying channels do not have reciprocity.Therefore,in this paper,a security key generation and encryption method of physical layer is designed in the strict time-varying channel.The algorithm generates the key through the extraction of the statistical characteristics of the channel and the combination of the chaotic function,and then encrypts the plaintext data.Analysis and simulation show that the algorithm is effective in resisting eavesdropper's eavesdropper,while the real user's BER performance remains unchanged.