Broadband MIMO Channel Modeling Research Based On Radio Channel Measurement

The research of radio channel propagation characteristics is significant to evaluation of wireless system, design of novel transmission technology and deployment of wireless networks. As the evolution of wireless communication, the emergence of broadband, multiple-input and multiple-output (MIMO) and cooperative communication (Relay) will greatly increase the capacity and coverage of next-generation mobile communication system. This thesis will focus on the channel propagation characteristics and modeling of next-generation wireless system based on wireless channel measurements. The main work of this thesis includes three points:(1) Calibration and simplification of IMT-Advanced channel evaluation model. IMT-Advanced channel model is a model based on geometry clusters. Several new features like 100MHz bandwidth, MIMO and polarization array have been introduced in IMT-Advanced channel model. However, these new features also make the IMT-Advanced channel model rather complex to use and realize. To solve this problem, this thesis has proposed a simplified model based on Kronecker product, which takes the antenna gain, angle power spectrum and Doppler spectrum characteristics into account. All of these are aimed at keeping simplified model's characteristics of frequency, time and spatial domain similar to IMT-Advanced model. The simulation results show that, the complexity of simplified model is only ten percent of that of the original model. In the other hand, a flowchart of calibration work of IMT-Advanced channel model is also been proposed to provide a criteria for the comparison of different model implementations, and this ensures the uniformity of channel model in the evaluation work.(2) The modeling and extraction of K factor in Ricean channel. Under the Ricean channel, some of the channel components'power is static and the channel envelope follows Ricean distribution. The constitution of channel power-static components is different according to the different conditions of environments. Based on the indoor stationary MIMO measurement results in Beijing University of Posts and Telecommunications, this thesis has studied the broadband fixed wireless access (BFWA) channel propagation characteristics, and proposed a new modeling method of Ricean factor K. This new model doesn't regard the line-of-sight (LOS) channel component as the only time-invariant component, and finds out that the channel time-invariant components exist in different delays and in which channel envelopes follow Ricean distribution. The origin of this phenomenon is the propagation characteristic of BFWA channel. The new modeling method is universal since it can be applied in different scenarios by changing the model parameters. In the other hand, when omni-directional array are used in channel measurements, the extraction of Ricean factor K will be inaccurate. The thesis presents a novel K-factor extraction method based on high-precision channel parameter estimation algorithm. The new method is suitable for mobile-receiver measurement scenario. It searches the most likely LOS component of channel and regards the LOS component as the only power-static component.(3) The extraction and analysis of correlation characteristics of Relay channel. The channel model of IMT-Advanced is applied as the evaluation model of LTE-Advanced system. However, the IMT-Advanced channel model lacks of the parameters of Relay scenarios, especially the correlation parameters newly introduced by IMT-Advanced channel model. In this thesis, a set of channel correlation parameters were given based on wireless channel measurements in the Relay scenarios. Furthermore, these parameters are compared with the same type of parameters of urban micro/macro cell for the sake of parameters validationThe main work and innovation of this thesis are stated above. The third point above was accepted by 3GPP RAN1 #55 meeting in Shenzhen, China. The first point was accepted by LTE+ promotion group in October 2009. All of these results are informative for the evaluation and simulation of next-generation wireless system.