Indoor High-frequency Broadband Time-varying Wireless Channel Measurement And Modeling

With the rapid development of wireless communications, people putforword higher requirements on the transmission rate and quality. In the case ofrecent extreme shortage of wireless spectrum, improving the spectrum utilizationand the channel’s transmission preformance become the focus of research. Whenthe signal is transmitted in the wireless channel, it will suffered channel fadingsuch as Doppler spreading caused by the movement of mobile station, theseeffects make wireless channel become unpredictable compared to wired channel.Wireless channel is the transmission medium of mobile communication.Channel fading characteristics directly determines the quality of transmission.Therefore, in order to transmit information as efficiently and reliably as possiblein the mobile condition, time-varying radio channel characteristics have to betaken account of cafully and modeled accurately. Doppler spread, which isemployed to describe the time-varying characteristic, is influenced by multipathpropagation and the moving of the mobile terminal. Doppler spread has a greatinfluence on the intercarrier distance, the channel estimation and data length ofthe frame.This thesis focus on the time-varying characteristics of wireless channelbased on channel measurements. According to the relationship between thechannel’s autocorrelation function Doppler power spectrum,based on the vectornetwork analyzer, a real-time channel platform was introduced,which operatingfrequency was6.00G~6.40GHz and bandwidth was400MHz.we selected theindoor line of sight and non-line of sight measurement environment and designeda detailed measurement program.Based on this platform, time-varying channelunder the LOS and NLOS indoor environments was measured. A large amount ofdata is employed for autocorrelation function and Doppler power spectrumestimation. Compared with the Jakes channel model, we analysised the featuresof Doppler power spectrum in LOS and NLOS wireless channel. In indoorenvironment, Doppler power spectrum was modeled as Gaussian function.Extracting and statistical analysising the model parameters, we achieved amethod of generating the random function of Doppler power spectrum.According to he random function of Doppler power spectrum,a method ofcalculating the reception signal wireless channel was given.The impact of small-scale fading when the signal transmits in wirelesschannel results in the performance degradation of communication system. Analysising the characteristics of Doppler power spectrum can optimize thedesign of the communication system. This Doppler power spectrum modelprovided supporting for the design and evaluation of the wireless communicationsystemto in the future.