Propagation channel measurement system development and channel characterization at 5.3 GHz

The wireless access has proven its usability for reliable communication and data conveying link for a long time. The ever growing usage of wireless communications systems has been driving the research to study even faster and more interference tolerant wireless solutions. A key concept towards achieving these goals are the detailed analysis and modeling of the propagation channel. In both of these aspects the availability of reliable measurement data is a prerequisite. This thesis concentrates on contributing to the measurement system development in single- and dual-link cases as well as measurement data analysis for specific wireless systems. In the first part of the thesis the physical radiowave propagation phenomena are briefly related to the challenges of the modern wireless communication systems. Through the analysis of the propagation channel conducted earlier in the literature, the main phenomena for modeling the propagation channel are illustrated, and the current modeling approaches are described. The hardware related design challenges are described along with the recent achievements in the measurement system development. Specifically, the design of antenna arrays for estimation of the parameters of the double directional channel model is illustrated. A measurement system developed for characterizing the double directional channel in the 5.3 GHz frequency range is presented along with the evaluation of the accuracy of the measurment system for the spatial characterization. The developed measurement system is further extended to enable simultaneous, double directional dual-link propagation channel measurements, and the first directional results from a measurement campaign are presented. In the second part, the important feature of the spatial dimensionality of the propagation channel is considered through measurement data acquired using the developed measurement system. The basics of the single- and dual-link MIMO communications systems and cooperative communications are presented. The analysis of the spatial domain used in MIMO communications systems is extended to multiuser scenario. Furthermore, cooperative communications system is analyzed.