Accelerating Development of Automotive Wireless Connectivity using Virtual-Drive Tests (VDT)
Accelerating Development of Automotive Wireless Connectivity using Virtual-Drive Tests (VDT)
Simulating Installed Antenna Performance, V2X and ADAS
Virtual drive tests allow for the testing and validation of car antenna designs and configurations in a simulated environment, without the need for costly physical prototypes. This enables designers and engineers to assess antenna performance and communication reliability of the car before committing to physical testing. The usage of VFT just keeps growing, mainly because of several reasons:
- Cost-effective: Conducting physical drive tests is typically very costly, as it involves setting up the prototype car, equipment, and personnel for the test. Due to the reduced development cycles prototype cars are hardly available anymore. Virtual drive tests eliminate the need for physical testing, thus reducing costs significantly.
- Flexibility: Virtual drive tests allow for more flexibility in testing different scenarios and configurations. It is easier and much more efficient to make adjustments and changes in a virtual environment compared to physical drive tests which involves preparing the car and equipment.
- Accuracy: Virtual drive tests can provide more accurate and precise results, as they allow for precise control over the environment, test parameters and conditions.
Overall, virtual drive tests for evaluating the installed antenna performance, the connectivity, also the ADAS radar sensor resolution capabilities, offer a cost-effective, flexible, efficient, and accurate alternative to physical drive tests on streets.
Altair Feko, including WinProp technology, provides a comprehensive solution and workflow to properly address virtual drive testing for automotive. WinProp’s highly accurate and very fast propagation models including ray tracing techniques cover a wide range of environments (rural, urban, tunnel, vehicular, …) and support arbitrary transmitters including cellular, vehicular and broadcasting ones, satellites, repeaters, and leaky feeder cables. For the network planning all relevant air interfaces are supported, including 5G, LTE, WiFi, GPS.
Our solution is also being used to create development environments for the connectivity systems of tomorrow, like with the DOC project, a Digital OTA Connectivity Twin. Such twin will significantly increase the safety of in-vehicle connectivity systems, addressing the challenges for V2X and V2V communication, evaluating complex environments with dynamic objects, variable drive paths and a wide range of antenna constellations.
We are showing below several cases as examples.
Import Maps of the Scenario
In advance the environment of interest can be set-up by converting map data from various formats, e.g. by downloading from openstreetmap.org including the building vectors and vegetation (see the video tutorial How to Convert Open Steet Map file in WinProp under youtube.com), or by downloading and converting topographical maps e.g. from USGS or other sources (have a look at the corresponding part of the WinProp intermediate level training).
Case 1: VDT to Evaluate Installed LTE / MIMO Antenna Performance for V2X Communication
For the evaluation and selection of the best car antenna configuration real drive tests are performed, which are more and more transitioned to VDT. A car equipped with different antennas is driving on 4.5 km long track around the LTE base station in a suburban scenario. At each position, the V2X radio channel is simulated. For this purpose the antenna patterns computed in Feko using full wave solvers considering the effects of mounting as well as the car geometry & materials can be imported in WinProp and attached to the corresponding trajectories. For 3 different antenna patterns (mirror antenna left/right hand side, backlight shelf antenna) the connectivity in terms of received power, feasible data rate and throughput is analyzed individually per antenna element. Then also different MIMO configurations are evaluated in downlink and uplink, see the following results:
A slide deck with step-by-step instructions as well as corresponding sample data can be downloaded here.
Case 2: V2V Communication in Urban Scenario – LTE vs IEEE 802.11p
The V2V connectivity is significantly impacted by the environment with expected coverage range of about 500m for line-of-sight conditions. In traffic scenarios on highways and especially in built-up areas this can be significantly reduced, as shown in the picture on the left. For the range analysis different antenna configurations can be evaluated and compared, also in terms of feasible data rates. The pictures below show different car antenna constellations and the impact of the air interface (LTE vs. WiFi) on coverage range and data throughput. Further demo projects in the domain of virtual-drive tests can be provided on request.
Case 3: VDT Validation in Test Bed Rosenheim – Simulations vs Measurements
Altair partners successfully used our solution for evaluating the V2X connectivity in the Rosenheim test network. Simulations were conducted at different frequency bands including band 28 at 763 MHz and band 7 at 2685 MHz to evaluate different antenna configurations and test the MIMO performance. The comparison of the simulated (red) and measured (green) RSRP signal levels along the 6 km long test track in Rosenheim city center shows good agreement.
Case 4: In-Vehicle Applications
Another popular use case is the simulation of the radio link in and around the vehicle for applications like in-cabin radar for person detection or remote keyless entry. Key strategy for the software defined vehicle is to reduce cable harness and vehicle weight by replacing cables by wireless links connecting different modules of the car. Simulation capabilities of RF link performance including signal strength, and data rate for SISO/MIMO configurations are predestinated for this purpose. These EM simulations can be used to support the antenna selection, the antenna placement and integration process as well as to assess the radio link quality inside the vehicle. For evaluating the installed antenna performance for different alternative antenna configurations in a very wide range of complex environments the virtual-drive tests offer benefits in terms of efficiency, flexibility, and costs.
Case 5: ADAS Radar Sensors
The virtual drive tests are also beneficial in the domain of ADAS radar sensors. Dynamic traffic scenarios can be configured using a library of traffic objects incl. cars, vans, bikes, traffic signs & lights, pedestrians and many more. Based on the sophisticated ray tracing solvers all rays which are backscattered from the environment are computed. This allows to evaluate the resolution capabilities of the radar sensor in terms of Range-Velocity heat maps. The picture above indicates how the objects present in the dynamic scene are showing up in the heat map at the relative velocity and corresponding distance from the ego car hosting the radar sensor. The pictures below show how the dynamic results at an intersection scene including many traffic objects are evolving over time (separated by 0.5s), including also the impact of the FMCW waveform using a postprocessing step.
Based on these capabilities the radar sensor performance for critical environments like tunnel entrance, bridge under-path, urban intersections etc. can be analyzed to further optimize the radar sensor configuration e.g. by comparing various alternatives for the radar antenna including mounting positions.
