A RF Propagation Modelling Methodology for Determining the Level and Nature of Scattering from Measurements

Wireless network evolution, spanning macro to micro elements, defies a universal modelling due to diverse channel responses. Tailoring accurate channel models for a dedicated applications like body area networks and urban communication [1-2] is paramount. Existing literature drawing from measurement and simulation [3-4] meets challenges, but a gradual surge of paradigm shift in millimeter-wave bands, emphasizes surface attributes (texture, granularity) over traditional properties [5]. While traditional tools suffice below 6 GHz, the ascent in frequency requires a profound understanding of scattering. Hence, the challenge involves comprehending the interplay between objects and waves across various angles, even in simulations. This pursuit necessitates resilience in scientific efforts to unravel wireless network complexities.
This study proposes a robust channel modelling approach using sparse Angle of Arrival (AoA) and Angle of Departure (AoD). It establishes a foundational framework by gradually introducing objects, irrespective of applications. Centred on metal objects in non-line-of-sight (nLoS) links, it explores their impact on signal transmission. The investigation, considering co-polar and cross-polar orientations, enhances understanding of electromagnetic polarization's role in signal quality and strength. Prior to taking on more intricate structures, it is imperative to master the correct procedures, the simplest case as a benchmark. Therefore, a sample metal plate is used to differentiate the reflection from the (baulk) material and the diffraction from its edges, thus be able to determine the scattering properties regardless of sample size considering the fact that a larger sample would tend to have a higher effective reflecting gain. Although, this measurements apply to any frequency, the data in this work will be presented at 3.5GHz.
The analysis with the metal plate establishes foundational benchmarks in terms of gain, beamwidth, and sidelobes for comparisons with Radar Cross Section (RCS) of more complex structures, including those with corrugation, varied material properties, or advanced technologies like Reconfigurable Intelligent Surfaces (RIS). Controlled environment allows focused analysis of reflection, scattering, and diffraction phenomena associated with the metal object. Additionally, a specifically chosen configuration [6] prioritizes signals influenced by nLoS components over direct ones. The use of a 90-degree transmit-receive offset is crucial, establishing a direct link between measured beamwidth and twice that of the reflected signal at a fixed angle of illumination. This unique setup provides a fresh perspective on data, closely tied to signal arrival and departure angles, enhancing insights with relevance to literature.