gr-RT Channel Emulator: Ray-Tracing-Based Channel Emulation for Environment-Aware PHY Wireless Research

Abstract

Data-driven physical layer (PHY) research increasingly depends on knowing the propagation channel that produced each received sample, yet the channel models available inside software-defined radio (SDR) frameworks are not tied to any physical environment. We present gr-RT Channel Emulator, a GNU Radio out-of-tree (OOT) module for position-aware, ray-tracing-assisted channel emulation. The module loads a three-dimensional scene described in Mitsuba XML, places one transmitter and one receiver at user-defined coordinates, and uses Sionna RT to compute propagation paths for a selected carrier frequency, antenna configuration, polarization, and interaction depth. The resulting paths are converted into a discrete complex channel impulse response and applied to streaming in-phase and quadrature (IQ) samples through a hierarchical wrapper around GNU Radio’s native channel model. Unlike an offline tracing workflow, in which taps are exported and later matched to a capture, our block publishes the taps it applied as a direct reference output, so that every impaired IQ stream remains paired with the channel that produced it. Node positions are updated at run time through message ports without rebuilding the flowgraph, and an optional lightweight viewer displays the scene together with the traced rays. We demonstrate the module with a flowgraph that recovers the applied taps by least squares (LS) and estimates the received signal-to-noise ratio (SNR) using only standard GNU Radio blocks, and we report snapshot latency across the bundled FAU, POWDER, and AERPAW scenes together with a preliminary comparison against measured POWDER channel estimates. Results suggest that the proposed module is a practical basis for controlled PHY experiments and for collecting IQ observations with explicit channel labels. The source code for this project is available at: https://github.com/C2A2-at-Florida-Atlantic-University/gr-RT_Channel_Emulator