Millimeterwave channel characterization for wehicular communications

Abstract

The increasing demand for more sensors inside vehicles pursues the intention of making vehicles more “intelligent”. This vision of fully connected, all-sensed, and autonomous cars are becoming more tangible and will become a reality in the coming years. The use of these intelligent transport systems will allow the integration of efficient management in terms of route control, fuel consumption, and traffic, among others. Wireless connections between vehicles, infrastructure, and pedestrians will be required to achieve this technology. Although technologies for this purpose already exist (Dedicate Short Range Communication, Cellular Mobile Network), their incursion into the market is still affected by different limitations. The growing interest in achieving higher transfer rates has begun to look towards a new route in terms of using the electromagnetic spectrum. The millimeter wave frequency bands have enough bandwidth to increase the capabilities of these systems, allowing the inclusion of real-time raw data transfer systems, entertainment, cloud computing, and other advantages. Despite these benefits, the use of millimeter frequency bands entails significant challenges for implementation (high losses due to atmospheric absorption, poor diffraction, high susceptibility to blocking, etc.). Although the disadvantages are several, in recent years academic and industrial activity in this research area has increased in response to the need for higher transfer rates. Before all this becomes a reality, a strict analysis of the characteristics associated with the wireless transmission channel at millimeter wave frequency bands must be conducted. The scenario in which vehicular communications occur is particularly unique, conditioned by low antenna heights, high mobility of the environment and scatterers around it, dynamic environments, and multiple link types. This Ph.D. research is aimed at providing knowledge in this study area, specifically the characterization of electromagnetic phenomena at millimeter wave frequency bands associated with vehicular communication. To achieve this objective, this research presents an empirical-experimental approach and simulation in ray-launching software. As the main results of this research, the author presents an in-depth characterization of small- and large-scale parameters within the vehicular wireless channel propagation media for millimeter wave frequency bands. Different scenarios and vehicular link types are taken into consideration and several remarks are presented for each of them. In parallel, various millimeter wave support capabilities are added to the in-house ray launching software to expand its features to dynamic vehicular scenarios and multi-antenna emulation. The correct characterization of these phenomena and the step-up improvements to the ray launching software will allow the evaluation of protocols in higher communication layers, as well as assess the viability of this technology in vehicular communication standards.