Research On Indoor Wireless Channel Measurement And Reverberation Chamber Based Channel Simulation

As the wireless channel is the medium over which wireless communication system transmits and receives signals,the channel characteristics significantly affect the com-munication quality.In order to evaluate the communication quality under fading channel-s,it is necessary to conduct an in-depth research on the wireless channel.Corresponding research can be divided into two parts.The first is to obtain the characteristics of the wireless channel under various real scenarios.This work can be accomplished by con-ducting channel measurements.The second is to simulate the channel under laboratory conditions in order to provide a reliable,controllable,and repeatable test environment for the communication quality evaluation under certain fading channels.In the recent decade,a significant progress on the insight to the channel measurement and simulation has been achieved after the great effort of global researchers;however,there are still the following limitations in the previous research:1)In terms of channel measurement in real scenarios,with the advent of the fifth-generation(5G)system,utilizing spectrum resources in the high frequency bands(above 6 GHz)has become a consensus.However,the research on channel character-istics in the high frequency is still inadequate,which severely limits the development of communication systems.2)In terms of channel simulation,reverberation chambers(RCs)can be used to simu-late different multipath environments by loading the RCs with different amounts of RF absorbers.In past research work,RCs were iteratively loaded with RF absorber-s for reaching a desired root mean square(RMS)delay spread.For every loading case,the RMS delay spread was measured.These repeated measurements were time consuming and inefficient.3)In terms of the communication quality evaluation,the current research focuses on the overall communications product performance.From the test results,it is difficult to analyze the various influencing factors separately.The physical layer parameters of communication standards are the key factors affecting the communication quality.The research on the physical layer performance is seriously inadequate,which limits the optimization of communication standards.In order to break these existing limitations,this dissertation conducts a research on channel measurement and channel simulation by means of experimental measurement,model construction,and theoretical analysis.The innovation of this dissertation mainly includes:1)The research in this dissertation is based on experimental measurement.In order to ensure the accuracy of the measurement results and the reliability of the research re-sults,the channel measurement system and the communication quality measurement system are studied first.With regard to the channel measurement system,in order to quantitatively evaluate the accuracy of the measurement results,the measurement un-certainties of two key channel characteristic parameters,i.e.,path loss and RMS delay spread,are analyzed based on Monte Carlo method.This analysis provides scientific references for the optimization of the channel measurement system.With regard to the communication quality,it is analyzed by measuring the modulation quality parame-ters.And by means of the comparison measurement,the consistency of measurement results of the modulation quality parameters for current main stream instruments is analyzed.It is found that the differences of the measurement results between different instruments are caused by different algorithms.This research is benefit to improving the accuracy and consistency of the measurement results,and lays a foundation for promoting the quantity unification of the modulation quality parameters.2)In terms of the channel characteristics in high frequency bands,the indoor channel at centimetre-wave bands(which are the candidate bands for the future communication systems)is investigated.Based on channel measurements,large-scale and small-scale statistics of line-of-sight(LOS)and non-LOS(NLOS)channels are analyzed.Of par-ticular interest is the impacts of the frequency on the channel characteristics.Based on the channel measurement results in the indoor scenarios,combined with the the-oretical analysis and the experiments in the RC,the relationship between the carrier frequency and the channel characteristics is studied.This research gives insight into propagation mechanisms in the high frequency bands.3)In terms of the channel characteristics in the RC,path loss and RMS delay spread are measured.Furthermore,the uncertainties of these measurements are evaluated.These uncertainties reveal the accuracy of the channel simulation.Based on the measure-ment results and theoretical analysis,a model is proposed to explain the quantitative relationship between the RMS delay spread and the parameters of loading.With this model,complex wireless channel with certain RMS delay spread can be quantitatively and effectively simulated with certain loading.4)A method to measure the communication quality in the RC is proposed based on the modulation quality measurement system.The measurement results reveal the per-formance of communication standard physical layer in fading channels.Based on measurement,the correlations between channel characteristics,communication quali-ty,and the two key configurations,i.e.,paddle position and absorber loading in the RC are investigated.The research reveals the action mechanism of channel characteristics on communication quality.In summary,this research focuses on channel measurement and channel simulation.The results of the research are useful for evaluating the communication quality under fading channels.The channel simulation is the basics of communication quality eval-uation.And the channel measurement is the basis of channel simulation,because the channel simulation device need to be configured according to the channel measurements.The channel measurement and channel simulation together form a technical support for communication quality evaluation.