Graphical Heatmap-Based Approach to Indoor Radio Signal Propagation: Adapting Advanced Ray Tracing and Global Illumination Algorithms

This article presents a novel approach for simulating indoor radio signal propagation through a heatmap-based strategy, harnessing advanced ray tracing (RT) and global illumination algorithms. Utilizing the desktop modeler SketchUp for 3-D environmental design and the V-Ray plugin for RT, this methodology leverages the spatial analysis of the light intensity. The process can be adjusted to various parameters of materials, including those that are intrinsically specular and transparent or are simulated as such, e.g., certain walls and windows. This generates a comprehensive heatmap of the predicted received signal strength indicator (RSSI) level of the radio signal. Unlike traditional empirical models, prone to inaccuracy with increasing complexity, and deterministic models, experiencing significant prediction time escalation with complexity, this approach provides a thorough view of signal propagation in complex architectural environments. It accounts for material properties that affect signal propagation, which are often overlooked by conventional models. Additionally, it exploits advanced graphics domain techniques, balancing accuracy and detail. The efficacy and accuracy of this approach are evaluated for Wi-Fi technology, and this approach is validated against established methods like the empirical multiwall model and the deterministic multiresolution frequency-domain ParFlow (MR-FDPF) method. A balance is achieved between precision, with a maximum deviation of 14.7% for RSSI
$= -100$
dBm, and computational efficiency, with rendering times typically ranging from units to tens of seconds at specific resolutions from 2 to 5 cm/pixel. Root mean squared error (RMSE) values between 5 and 8 dB are deemed acceptable, showcasing the approach’s robustness and practical applicability.