NexaSim is a state-of-the-art 3D Unified Communication Network Simulator developed for the European Union's Horizon Europe NexaSphere research and innovation project.
Built upon the modular foundation of Artery, NexaSim evolves traditional vehicular and terrestrial simulation into a full-scale three-dimensional, multi-tier network architecture spanning:
- Terrestrial Networks (TN): V2X (ETSI ITS-G5, GeoNetworking, C-V2X), 5G New Radio (3GPP Rel 15/16 gNodeB / UE via Simu5G), and SUMO microscopic traffic co-simulation.
- Non-Terrestrial Networks (NTN): Low Earth Orbit (LEO) mega-constellations (Starlink, Kuiper, Walker-Delta), SGP4 orbital propagation (via space_veins), optical laser (1550 nm) & RF (Ka/V-band) Inter-Satellite Links (ISL), phased-array user terminals, and Ground Station feeder links.
- Unified 3D Multi-RAT Orchestration: Seamless Dual-Connectivity (DC), make-before-break satellite handovers, multi-link path routing, and dynamic failover between terrestrial cellular and space-based backhauls.
NexaSim eliminates internal legacy submodules (extern/) in favor of Conan 2 package management:
- All dependencies (
INET 4.2.2,Simu5G 1.1.0,space_veins 0.3,Vanetza 26.02,Boost 1.86,GeographicLib,Crypto++) are managed, pinned, and built through native Conan recipes (recipes/). - Isolated, reproducible builds with persistent caching (
artery-conan2-cache) reduce incremental build setup times from ~35 minutes to seconds.
- Unified Mobility Manager coordinates vehicles, road-side units (RSUs), drones (UAVs), high-altitude platforms (HAPS), LEO satellites, and ground stations across a single coordinate reference frame (
inet::Coord& WGS84 Geodetic). - Real-time position updates driven simultaneously by SUMO TraCI (terrestrial vehicles) and SGP4 orbital propagation (satellites).
- Simu5G 5G-NR Integration: Standalone & Non-Standalone gNodeBs, User Plane protocol stacks, dynamic scheduling, Carrier Aggregation, and Beamforming.
- Vanetza ITS-G5 Stack: GeoNetworking (ETSI EN 302 636), BTP, Decentralized Congestion Control (DCC), and standard V2X services (CAM, DENM, CPM).
- Orbital Mechanics: Walker-Delta parametric constellations, multi-shell Starlink configurations, and custom Two-Line Element (TLE) ephemeris parsing.
- Inter-Satellite Links (ISL): Realistic Pointing, Acquisition, and Tracking (PAT) modeling with optical beam divergence, pointing jitter, Doppler shift, and atmospheric/space link budgets.
- Smart User Terminals: Phased-array electronic steering with beamforming weight computation, multi-satellite tracking, and predictive make-before-break handovers.
+-----------------------------------------------------------------------------------+
| NexaSim |
| 3D Unified TN-NTN Multi-Tier Simulation Framework |
+-----------------------------------------------------------------------------------+
| |
| +-----------------------------------+ +-----------------------------------+ |
| | Terrestrial Network (TN) | | Non-Terrestrial Network (NTN) | |
| |-----------------------------------| |-----------------------------------| |
| | • ETSI ITS-G5 (Vanetza) | | • LEO Constellations (Walker/TLE) | |
| | • 5G New Radio (Simu5G) | | • Optical & RF ISL (ISLNic) | |
| | • SUMO TraCI Traffic Co-Sim | | • Space Veins SGP4 Orbit Engine | |
| | • C-V2X / DSRC & Radar Sensors | | • Phased Array User Terminals | |
| +-----------------------------------+ +-----------------------------------+ |
| \ / |
| +-------------------------------+ |
| | Unified Multi-RAT Coordinator | |
| | • 3D Unified Mobility Manager | |
| | • Dual Connectivity (TN+NTN) | |
| | • Make-Before-Break Handovers | |
| +-------------------------------+ |
| | |
| +-------------------------------+ |
| | OMNeT++ 5.6.2 / INET 4.2.2 | |
| +-------------------------------+ |
| | |
| +-------------------------------+ |
| | Conan 2 Package Ecosystem | |
| +-------------------------------+ |
+-----------------------------------------------------------------------------------+
NexaSim runs inside an optimized Docker environment providing all dependencies and build toolchains.
# Compile NexaSim (fast parallel Ninja build with Conan 2 caching)
docker compose run --rm nexasim-build(Legacy alias docker compose run --rm artery-build is also supported).
NexaSim comes with pre-packaged scenarios demonstrating TN-NTN multi-tier communications:
# Execute Starlink + Berlin 5G-NR Dual-Connectivity scenario
docker compose run --rm nexasim-scenario# Generate analytical plots (throughput, latency, handover CDFs, ISL link quality)
docker compose run --rm nexasim-analyzePre-configured YAML scenarios are provided in scenarios/library/:
| Scenario | Domain / Focus | Key NexaSphere Features |
|---|---|---|
stelvio_pass_hybrid.yaml |
Alpine Mountain Automotive | 3D mountain orography, 5G blackout gorge, Starlink LEO tracking, crash failover & V2V relay |
nexasphere_highway_platooning.yaml |
Autonomous Truck Platooning | 4-truck convoy on A22 highway, <5ms V2V sidelink string stability, hybrid LEO cloud gateway |
nexasphere_emergency_corridor.yaml |
Connected Ambulance Telemedicine | 120 km/h ambulance, 4K ultrasound video streaming, dynamic 5G/LEO Multi-RAT steering & preemption |
nexasphere_urban_canyon_cpm.yaml |
Urban Canyon & Perception | High-rise skyscraper masking (48° mask), microcell 5G beamforming, ETSI Collective Perception (CPM) |
nexasphere_uav_corridor.yaml |
Aerial UAV Infrastructure Corridor | Drones at 250m altitude transitioning between sparse 5G cells and LEO satellite backhaul |
nexasphere_maritime_sar.yaml |
Offshore Maritime Search & Rescue | Deep sea vessels & sensor buoys with pure NTN LEO coverage, distress beacon & laser ISLs |
nexasphere_rail_highspeed.yaml |
High-Speed Rail (300 km/h) | Fast train TN-NTN handover, Doppler shift compensation, Apennine tunnel outage recovery |
For complete reference on YAML syntax, simulation workflows, data analysis, and 3D visualization, see the NexaSim Complete User Manual.
# Unified CLI Workflow (Recommended):
./nexasim list # List all available scenarios in library
./nexasim validate stelvio # Validate scenario specification (Pydantic / Schema)
./nexasim run stelvio # Run scenario in headless mode
./nexasim run stelvio --gui # Run with Qtenv & SUMO-GUI Virtual Desktop (http://localhost:6080/vnc.html)
./nexasim analyze stelvio # Evaluate KPIs and generate interactive Chart.js dashboard
./nexasim sweep emergency_corridor --param switchingMode=coverage-based,qos-based # Parameter sweep benchmark
./nexasim view-3d stelvio # Launch 3D Space-Ground Digital Twin (CesiumJS)
./nexasim studio # Start Web Control Center (http://localhost:8080)
./nexasim all highway_platooning # End-to-end (generate -> run -> analyze).
├── nexasim # Root CLI launcher
├── CMakeLists.txt # Root CMake project (NexaSim)
├── conanfile.py # Conan 2 package definition
├── conandata.yml # Dependency version locks
├── docker-compose.yml # Containerized build & execution orchestration
├── Dockerfile # Multi-stage Ubuntu build environment
├── recipes/ # Conan 2 package recipes (inet, simu5g, space_veins, vanetza)
├── src/
│ ├── artery/
│ │ ├── ntn/ # Non-Terrestrial Network engine (ISL, Constellations, User Terminal)
│ │ ├── nr/ # 5G-NR Simu5G integration
│ │ ├── inet/ # INET 4.2.2 radio & mobility adapters
│ │ ├── hybrid/ # Multi-RAT Vertical Handover & MEC Offloading
│ │ ├── application/ # V2X ITS-G5 services & middleware
│ │ ├── envmod/ # Environmental perception & radar sensors
│ │ └── utility/ # Coordinate transforms, math, asio tasks
│ └── traci/ # SUMO TraCI interface & node managers
├── scenarios/
│ ├── library/ # Declarative YAML scenario specifications
│ ├── schema/ # Pydantic JSON Schema for YAML autocompletion
│ └── generated/ # Auto-generated OMNeT++ & SUMO runtime files
└── tools/
├── nexasim.py # Core CLI implementation
├── studio.py # Interactive Web Studio & Control Center
├── sweep.py # Sensitivity study & parameter sweep runner
├── czml_generator.py # 3D Cesium globe & CZML digital twin generator
├── sumo_generator.py # Procedural SUMO network generator
├── gen_scenario.py # YAML to OMNeT++ scenario compiler
├── analyze_results.py # KPI evaluation engine
└── dashboard.py # Executive Chart.js interactive dashboard
In alignment with the Horizon Europe NexaSphere technical objectives:
- Milestone 1: Modern Conan 2 Zero-Submodule Architecture & Multi-Domain Mobility (Completed).
- Milestone 2: Unified CLI & Procedural SUMO Traffic Generation (Completed).
- Milestone 3: Dynamic Multi-Tier VHO & Hierarchical MEC Edge Computing (Completed).
- Milestone 4: Multi-Run Benchmark Suite, 3D Digital Twin (CesiumJS) & Web Studio (Completed).
- Milestone 5 (Upcoming): Multi-Hop Inter-Satellite Mesh Routing using Contact Graph Routing (CGR) and dynamic space Dijkstra.
- Milestone 6 (Upcoming): Reinforcement Learning (Deep Q-Network / PPO) for predictive make-before-break vertical handover.
- Milestone 7 (Upcoming): 3GPP Rel. 16/17 5G-NR V2X Sidelink (PC5) integration with Collective Perception Service (CPM).
- NexaSphere: Developed under the European Union's Horizon Europe research framework for 3D unified communication networks.
- Artery: Based on the Artery V2X Simulation Framework (Raphael Riebl et al., GPLv2).
- Core Components: INET Framework, Simu5G, space_veins, and Vanetza.