Radio wave propagation modeling by combining ray-tracing with integral representations

• Applicant: Professor Dr.-Ing. Thomas Eibert
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 443636075

Efficient and accurate modelling approaches for radio wave propagation become increasingly important towards an improved understanding of the continuously evolving communication and sensing functionalities with radio waves. Ray-tracing is undoubtedly the most powerful approach for wave propagation in complex large-scale environments, but it has also certain limitations, especially when realized in the form of field based geometrical optics approaches. In the first part of this project, the applicant has combined a powerful ray-tracing framework with the concept of Huygens’ surface integral representations. As such, complex and large environments can be partitioned into smaller and less complex parts, and especially also the coverage range of the ray-based representation can be considerably increased, while even including diffraction effects in a natural way. In this continuation project, the capabilities and the efficiency of the hybrid approach shall be further improved by integrating hierarchical data structures, as known from the multilevel fast multipole methods, for the field/sources representation on the Huygens’ surfaces. With these data structures, the number of necessary ray shoots will be considerably reduced, where the algorithm will adapt automatically to the specific environment in order to maintain good accuracy. Since the concept of Huygens’ integral representations over appropriate Huygens’ surfaces provides a flexible partitioning of a considered propagation environment, the ray-tracing framework will be further extended by combining it with full-wave numerical modelling techniques, which are utilized to compute the scattering and radiation behavior of not too large complex objects. Incident fields for the full-wave computations are provided by incident rays and the scattered or radiated fields can in turn be used for determining the Huygens’ sources for the continuation of the ray-tracing outside of the object. Further, advanced ray-path prediction strategies will be investigated and realized, which improve the capabilities of the ray-tracing approach towards diffraction and refraction computations, where in particular the accurate and efficient evaluation of the highly oscillatory Huygens’ integrals is a challenge. Finally, the hybrid ray-tracing framework will be utilized and further adapted for highly-accurate radar imaging in reverberant environments, where full inverse source solutions based on numerical Green’s functions of the imaging environment computed by the ray-tracing framework will be utilized to produce high-quality images. All of the new algorithms will be implemented and validated for high-power graphics processing units.

• DFG Programme: Research Grants