A Site-Specific Indoor Wireless Propagation Model

In this thesis, we explore the fundamental concepts behind the emerging field of site-specific propagation modeling for wireless communication systems. The first three chapters of background material discuss, respectively, the motivation for this study, the context of the study, and signal behavior and modeling in the predominant wireless propagation environments. A brief survey of existing ray-tracing based site-specific propagation models follows this discussion, leading naturally to the work of new model development undertaken in our thesis project. Following the detailed description of our generalized wireless channel modeling, various interference cases incorporating with this model are thoroughly discussed and results presented at the end of this thesis

An extension of the RiMAX multipath estimation algorithm for ultra-wideband channel modeling

This work presents an extension of the high-resolution RiMAX multipath estimation algorithm, enabling the analysis of frequency-dependent propagation parameters for ultra-wideband (UWB) channel modeling. Since RiMAX is a narrowband algorithm, it does not account for the frequency-dependency of the radio channel or the environment. As such, the impact of certain materials in which these systems operate can no longer be considered constant with respect to frequency, preventing an accurate estimation of multipath parameters for UWB communication. In order to track both the specular and dense multipath components (SMC and DMC) over frequency, an extension to the RiMAX algorithm was developed that can process UWB measurement data. The advantage of our approach is that geometrical propagation parameters do not appear or disappear from one sub-band onto the next. The UWB-RiMAX algorithm makes it possible to re-evaluate common radio channel parameters for DMC in the wideband scenario, and to extend the well-known deterministic propagation model comprising of SMC alone, towards a more hybrid model containing the stochastic contributions from the DMC's distributed diffuse scattering as well. Our algorithm was tested with synthetic radio channel models in an indoor environment, which show that our algorithm can match up to 99% of the SMC parameters according to the multipath component distance (MCD) metric and that the DMC reverberation time known from the theory of room electromagnetics can be estimated on average with an error margin of less than 2 ns throughout the UWB frequency band. We also present some preliminary results in an indoor environment, which indicate a strong presence of DMC and thus diffuse scattering. The DMC power represents up to 50% of the total measured power for the lower UWB frequencies and reduces to around 30% for the higher UWB frequencies

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