Research Of The Wireless Channel Measurement And Channel Modeling Under High Speed Railway Based On TD-LTE

The rapid development of high speed railway (HSR) has spurred great interest in wireless communication under high speed railway. Compared with traditional wireless communication system, as the HSR environment has properties of abundant scenarios and larger Doppler shift, it is of great importance and necessities to establish the proper channel model for the wireless communication system under HSR.According to the general methods of studying the wireless communication system, this thesis studies the HSR channel model reference to three procedures which include channel measurement, data processing and channel modeling. HSR has faced many problems including the complicated scenarios, the larger penetration loss, and the larger Doppler shift. All of these questions have brought great difficulties to our measurement. Considering the specialties of HSR environment, our measurement should meet the requirements in aspects of the bandwidth, Doppler shift, the storage speed and so on. Meanwhile, it should also have lower cost, higher efficiency and stronger extensibility. Therefore, this thesis adopts the measurement scheme which can obtain the properties of large-scale fading and small-scale fading in one time for higher measurement efficiency, and also gives out the2X2measurement in order to support the measurement of multiple input multiple output system better. The feasibility of these schemes were testified by simulating the above procedures using the WINNER II channel model.In general, there are two aspects that describe the channel characteristics. They are large-scale fading and small-scale fading properties. In this thesis, we acquire the large-scale and small-scale data in one measurement. Reference to the minimum mean square error (MMSE) criterion and curve fitting, we obtain the path loss factor and shadow fading variance in order to establish the large-scale channel model for viaduct, plain, hilly terrain scenarios under HSR. It is known to us all that small-scale fading characteristics have an effect on the design of the receiver. Therefore, we do some research on the small-scale fading properties. There are three steps for the acquirement of small-scale characteristics which are the selection of the effective samples, settings of the noise floor and the determination of the multipath threshold. After the acquired channel impulse response (CIR) and power delay profile (PDP), we do some mathematical operations to extract the channel parameters including the RMS delay, Doppler frequency shift, the number of multipath and K-factor. These results provide the data foundation for the channel modeling.Finally, this thesis introduces the tapped-delay-line models and demonstrates our methods to gain the channel model. Based on the extensive body of measured data under viaduct, plain and hilly terrain scenarios, the following parameters are specified for each tap including the number of taps, the excess time delay and the average path gain, and the Doppler shift. All these results and models are expected to provide an insight into the behaviors and performance of wireless cellular communication in HSR scenarios.