Research On Wireless Channel Measurement Method Based On Software Radio Technology

Wireless channel fading and multipath effects are important for the performance of wireless communication systems.Therefore,for designing and optimizing wireless communication systems,it is of great significance to measure and obtain statistical parameters of wireless channels.With the popularity of wireless communication terminals and applications,the research of wireless channel modeling based on big data is getting more and more attention.However,the existing channel measuring equipment is expensive and bulky,which is not suitable for large-scale channel measurement and data collection.Therefore,research and development of low-cost,high-flexibility and reasonable accuracy channel measurement system has important application value.Based on the openness,versatility and flexibility of software-defined radio,this thesis combines wireless channel measurement and software-defined radio technology.By studying the principles of wireless channel modeling and measurement,this thesis develops a wireless channel measurement system based on software-defined radio.And the channel measurement system is verified and applied.The main content of this thesis is as follows:Firstly,this thesis studies the classic channel model and the modeling principles of wireless channel.And it compares common channel measurement methods,including frequency sweep method,continuous wave measurement method,direct pulse method and spread spectrum sliding correlation method.Then this thesis studies the hardware and software platform of software-defined radio.Considering the development cost,performance parameters and project requirements,Hack RF One and GNU Radio are selected to develop the transceiver part of the channel measurement system.In order to provide a basis for the wireless channel measurement scheme,this thesis deeply analyzes its hardware and software architecture and parameter configuration,and evaluates its performance indicators.Secondly,this thesis focuses on the principle of spread spectrum sliding correlation method,and compares the correlations of m sequence,M sequence,gold sequence and CAZAC sequence.Taking the spread spectrum sliding correlation method as the measurement method and the m-sequence as the detection sequence,this thesis designs a wireless channel measurement scheme.Then,this thesis simulates the effect of signal-to-noise ratio and sequence length on the estimation of channel characteristics.The processing flow of the received data is established,including frame synchronization processing,continuous sliding correlation processing,iterative sliding correlation processing,and channel statistical characteristic estimation processing.Finally,this thesis measures the actual transceiver signal waveform,corrects the reception error,and verifies the stability of the transceiver part.In addition,this thesis uses two methods,channel measurement and ray tracing,to characterize the shielded room channel.By comparison,the delay and amplitude of the two channel impulse responses obtained respectively are basically the same.The average value of the relative error between the measurement result and the simulation result is 0.26%,which verifies that the channel measurement system has effective measurement functions and reasonable accuracy.Then this thesis obtains the channel impulse response by measuring the corridor channel,and distinguishes three clusters of multipath signals with relative delays of 200 ns,500ns and 800 ns.This thesis analyzes the statistical characteristics of the main path amplitude,and calculates that it follows the Rice distribution with a Rice factor of 61.03.In addition,this thesis analyzes the statistical characteristics of the second-path signal amplitude and relative delay,and obtains its pdf and cdf respectively.The amplitude of the second path follows a double Gaussian distribution and the relative delay follows a Gaussian distribution.The relative error between fitting and theory is within the acceptable range.