Enabling Site-Specific Cellular Network Simulation Through Ray-Tracing-Driven ns-3

2025-08-05

AI Summary

Traditional 3GPP statistical channel models lack scene-specific fidelity—e.g., street canyons, corner diffraction, or deterministic line-of-sight (LOS) propagation—leading to insufficient accuracy in system-level simulations. To address this, we propose a trajectory-driven, site-specific channel modeling framework that tightly couples the Sionna ray tracer with ns-3/5G-LENA. This integration converts geometrically accurate multipath components into frequency-domain channel matrices and embeds them seamlessly into the PHY/MAC protocol stack, preserving full 3GPP standard compliance while enabling high-fidelity simulation. The method supports digital twin research from 5G-Advanced to 6G. Experimental validation demonstrates its superior capability in capturing beamforming performance and end-to-end key performance indicators—including throughput knee points and coverage outages—significantly outperforming conventional statistical models.

Technology Category

• Search and Optimization: Sampling/Simulation-based Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Application Domains: Mobility, Driving & Flight

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• User Modeling, Personalization and Recommendation: User modeling and simulation for interactive and conversational systems
• Web Mining and Content Analysis: Web data generation and simulation

Abstract

Evaluating cellular systems, from 5G New Radio (NR) and 5G-Advanced to 6G, is challenging because the performance emerges from the tight coupling of propagation, beam management, scheduling, and higher-layer interactions. System-level simulation is therefore indispensable, yet the vast majority of studies rely on the statistical 3GPP channel models. These are well suited to capture average behavior across many statistical realizations, but cannot reproduce site-specific phenomena such as corner diffraction, street-canyon blockage, or deterministic line-of-sight conditions and angle-of-departure/arrival relationships that drive directional links. This paper extends 5G-LENA, an NR module for the system-level Network Simulator 3 (ns-3), with a trace-based channel model that processes the Multipath Components (MPCs) obtained from external ray-tracers (e.g., Sionna Ray Tracer (RT)) or measurement campaigns. Our module constructs frequency-domain channel matrices and feeds them to the existing Physical (PHY)/Medium Access Control (MAC) stack without any further modifications. The result is a geometry-based channel model that remains fully compatible with the standard 3GPP implementation in 5G-LENA, while delivering site-specific geometric fidelity. This new module provides a key building block toward Digital Twin (DT) capabilities by offering realistic site-specific channel modeling, unlocking studies that require site awareness, including beam management, blockage mitigation, and environment-aware sensing. We demonstrate its capabilities for precise beam-steering validation and end-to-end metric analysis. In both cases, the trace-driven engine exposes performance inflections that the statistical model does not exhibit, confirming its value for high-fidelity system-level cellular networks research and as a step toward DT applications.

Problem

• Enabling site-specific cellular network simulation via ray-tracing
• Addressing limitations of statistical 3GPP channel models for 5G/6G
• Providing geometric fidelity for beam management and blockage mitigation

Innovation

• Ray-tracing-driven ns-3 for site-specific simulation
• Trace-based channel model with external ray-tracers
• Geometry-based channel compatible with 3GPP standards