Wideband Channel Measurements And Investigation On Channel Modelinng

In the design process of wireless communication system, features of radio channel must be given adequate consideration. Signals transmitting through the air often suffer from interference, fading, and the Doppler spread caused by the movement of both mobile stations and the scatters. Therefore, radio channels are more complex than wired channels. A direct and accurate way to acquire the radio channel features is to do channel sounding. Channel impulse response can be collected, and key channel parameters can be extracted with the help of sounding equipment. These parameters can provide fundamental basis for the research and design of communication system.Based on extensive channel measurement, this thesis verified and compared some typical channel models, and analyzed the features of a few typical point-to-point channel models. Besides, a novel relay channel model is proposed. The work in this thesis includes:Various point-to-point broadband channel models have been proposed which can be divided into two categories considering the way of channel impulse response generation:geometry-based stochastic channel models(GSCM) and correlation-based stochastic channel models(CSCM). WINNER channel model is a typical GSCM while Kronecker channel model a typical CSCM. WINNER channel model requires a large amount of parameters and is highly computational complicated, yet it is considered to simulate radio channels more accurately because it is proposed based on extensive channel measurement. On the other hand, Kronecker channel model requires very few parameters and is very simple, yet it is considered to be inaccurate. In this thesis, a method is proposed to compare the WIMII and Kronecker channel models fairly with metrics including channel capacity, channel eigen-values and symbol error rate(SER). Results show that WINNER channel model are more accurate than Kronecker channel model in most of the cases. However, in some other cases, Kronecker channel model can be used instead of WINNER channel model to achieve almost same result, but with shorter simulation time.A reliable channel model should not only balance between accuracy and computational complication but also simulate all physical phenomenon in the radio channel in a not misleading way. International mobile telecommunication-Advanced (IMT-Advanced) channel model is a standardized channel model based on WINNER channel model, it has been extensively used in the simulation verification and product testing. In this thesis, a solution for non positive-definition cross-correlation matrix by simplifying the cross polarizations between large scale parameters has been proposed. Besides, IMT-Advanced channel model's modeling method of K-factor in NLOS case is proved to be over-simplified with the comparison of measurement results.In the last decade, relay multiple-input multiple-output system was proposed to meet the demand of the system throughput. However, an over-simplified relay channel model with two hops, each of which is modeled by Rayleigh distribution, was often used in the research. In the thesis, a new relay channel model based on IMT-Advanced channel model is proposed. Channel outage capacity in both amplify-and-forward and decode-and-forward relaying modes are chosen as metrics. With the measurement channel capacity as baseline, it is shown the new relay channel model has better performance than traditional one.Modifying and optimizing channel models based on channel measurement is a reliable way to get more accurate channel models, which can in turn provide insight for the design of future wireless communication system.