Fig 1.
Opal can be used as a standalone application, as a plugin with Veneris or loaded with OMNET++.
Fig 2.
Workflow and types of simulations with Veneris and Opal.
First, the scenario is built from real-world map data. Then, three alternatives are available: (1) to carry out the electromagnetic characterization of the scenario, just with Opal; (2) to run a unidirectional hybrid simulation, where the traffic simulation output is stored and then fed to the OMNET++ modules; (3) to run a bidirectional simulation, where traffic and network simulation are run simultaneously and interact with each other.
Fig 3.
There are three groups in the graph: buildings or other static interactive environment elements, vehicles or any other moving interactive elements and receivers, which can be moved but since are made of spheres, do not need transformation matrices.
Fig 4.
Web-based scenario generation.
With a web interface the user selects an area from OSM and generates the scenario. The files can be downloaded but it can also be run directly on the browser, as shown in the figure, to check the results. Part of the Figure shows a map from OpenStreetMap: ©OpenStreetMap contributors.
Fig 5.
To increase the simulation accuracy the Cartagena city scenario has been enhanced with terrain elevation data and high accuracy building data from public spatial information sources. Snapshot taken from the Opal tool.
Fig 6.
The tunnel has been procedurally generated and the Unity Editor menu has been extended to generate the scenario. Snapshot taken from the Opal tool.
Fig 7.
Simulation of received electric field at cross sections at z = 100 m and z = 900 m of a rectangular tunnel with dimensions 8.5m x 5m x 1000m, EM properties ϵr = 5 and σ = 0.01 S/m. The origin of coordinates is at the center of the rectangle and beginning of tunnel. Transmitter is placed at [-3.85,1,0] and both transmitter and receivers use vertical polarization with frequency 900 MHz. Maximum number of reflections is 20. Results show electric field computed with RDN and LPR simulations with different reception sphere radius (r) and either half isotropic (ISO) or sectorized (SEC) ray generation with different ray densities (rd). (a) Electric field for cross section at z = 100 m. (b) Electric field for cross section at z = 900 m.
Fig 8.
Received electric field for a circular tunnel of radius 2 m and length 1500 m and EM properties ϵr = 12 and σ = 0.02 S/m. Origin of coordinates is at center of circle at the beginning of tunnel. Transmitter is placed at [1.8, 0,0] m and transmits with vertical polarization at 1GHz. Sectorized ray generation (SEC): each sector spanning 10 degree of elevation by 10 degree of azimuth until the complete forward hemisphere is simulated. Maximum number of reflections is 40. Figure is to be compared with Fig 13 from [17].
Fig 9.
Magnitude of the total (direct, reflected, diffracted) received electric field at receiver points around a straight perfect conductor edge (square angle between faces, n = 1.5). Receivers are placed on a full circumference of radius s = 20 m around the edge at 1 degree steps. A transmitter at f = 1.8 GHz with vertical polarization is placed at an angle of 45 degrees from the edge closest face and m from the edge. (a) Total received field. (b) Geometry of the scenario.
Fig 10.
Comparison of measurements at 1.8 GHz and simulation in the city of Cartagena.
The generated scenario includes 1067 buildings and 15082 diffraction edges. 898 receivers were simulated simutaneously. Each simulation point show the average of 10 replications. (a) Urban measurements. (b) Snapshot of a heatmap of the received EM field.