An OTA test system supporting full vehicle 5G MIMO measurement

Product Description

GTS’s mobile vehicle OTA test system is a set of innovative integrated design, the overall mobile OTA test system for the whole vehicle. It can be formed as an independent test system or integrated into the original automotive EMC test chamber to achieve one-room reuse. When car OTA test is required, the mobile car of the mobile car OTA test system carries a robotic arm and a test antenna, and enters the EMC darkroom through electronically controlled movement. The test software automatically locates and finds the test initial point, and the test process is fully automated. After the test is completed, the OTA test system can be moved to the designated position, completely avoiding the impact on the EMC test, and realizing the mutual compatibility and non-interference of the two systems.

A single set of robotic arms can be used to test the antenna and SISO performance of the entire vehicle; four sets of robotic arms work together to complete vehicle MIMO and self-interference tests.

The movable robotic arm supports high-precision hemispherical scanning (theta angle is between -0.5° and 96°), with millimeter-level motion accuracy. The scanning device can achieve a rotation accuracy better than ±0.15°, which fully meets the current communication frequency band test requirements. . This scan mode is suitable for vehicle bodies within 6m×2m×2m, and can test various communication antennas. The high-performance EPP rigid foaming process wave absorbing material is laid on the key parts of the robot arm and the mobile car, as well as on the ground, which can be moved repeatedly, without deformation, without powder and slag, and the absorbing performance is not easy to be degraded, so as to ensure It ensures the long-term stable and reliable use of the test system. The test system also provides a number of options, leaving room for upgrades to meet more testing needs in the future.

The mobile car OTA test system is composed of an electronically controlled mobile trolley carrying a retractable robotic arm and a clamped test antenna. It is a high-precision vehicle-level OTA test system with visual positioning guidance and auxiliary positioning calibration. The system mainly includes the following parts:

Electronically controlled mobile platform

The platform uses AC220V/32A AC power supply, with wired and wireless control modes. There are 4 chakras on the bottom of the mobile platform, which can achieve movement in any direction. The car body is equipped with a liftable electric cylinder to support the entire car body and stabilize the chassis. The vehicle chassis is equipped with a visual positioning system to realize automatic driving of two-dimensional code navigation. The body comes with a level gauge. After the trolley moves to the designated position, the level of the body can be detected. It also supports feedback adjustment. It can support the four outriggers with one key and keep it level with the ground.

Test Rod

Used to connect the end of the robotic arm and the test antenna fixture, it is made of carbon fiber, light weight, high precision and high strength. The test rod is composed of four parts, the connector A holds the test antenna, and the cable passes through the middle; the connector B is connected to the port of the manipulator; the high-definition visual recognition calibration module on the connector B can perform XYZ axis for the position of the ground surface recognition point And the calibration of rx, ry, rz angles; high-definition high-resolution camera for visual positioning, can achieve accurate calibration of the B end of the connector.

Test Antenna

The car antenna test probe specially used for general testing is adopted, which has the characteristics of low RCS, wide beam width, high cross-polarization ratio, and low standing wave. The movable manipulator has a small footprint and is easy to move. It is equipped with two sets of telescopic systems. One is the 6-degree-of-freedom mechanical expansion and contraction of the manipulator. It can be retracted to less than 2.5m, so that the device can enter and exit the darkroom door with a height of more than 3m. Another telescopic system is the 4 outriggers that come with the mobile platform, which can be extended to a maximum of 2.5m×2.5m, which expands the force-bearing area and makes the robotic arm scanning more stable.

Robotic Arm

The manipulator is imported from Switzerland, industrial grade manipulator, which has been widely used in automobile, ship and aircraft manufacturing. High precision and reliability.


Wide beam, high cross-polarization measurement probe

For automotive testing, due to the near-field eccentricity, in order to ensure the accuracy of the measurement results, the main lobe of the test probe must effectively irradiate (that is, full coverage) the radiation position of the antenna under test (often the entire vehicle). The cross-polarization of the effective coverage beam is also the core index for the correct realization of the near-far field conversion. The eccentric system needs a high cross-polarization isolation to meet the near-far field conversion requirements. Since the automobile test needs to use the near-far field transformation, and one of the conditions of the near and far field transformation is to accurately distinguish the energy of the H polarization and the V polarization, the cross-polarization ratio of the entire main lobe energy of the test probe should be higher than 18dB, In order to meet the near-far field conversion test accuracy requirements. In order to achieve high-precision testing, Universal Test has designed an automotive-specific measurement probe.

Radiated Two-Stage (RTS) MIMO Testing

RTS is one of the two MIMO test methods approved by 3GPP/CTIA, and the general test has the RTS core patent. According to the characteristics of the vehicle test, we designed a special MIMO test scheme, using the radiation two-stage method to achieve accurate and efficient vehicle multi-antenna wireless performance test under complex electromagnetic environment. This solution supports 2×2/4×4 MIMO performance evaluation and is suitable for LTE and 5G sub6G (NSA/SA) communication systems. With the wireless channel emulator, dynamic MIMO tests under standard channel models can be performed, and even environmental simulations of rain, fog, terrain, dynamics, etc., as well as scenario road conditions can be simulated.

The advantages of moving the external environment into the darkroom are as follows:

  • Parameters can be controlled
  • model normalization
  • The scene can be repeated
  • test high efficiency
Near and far field algorithm based on error analysis

The near-far field transformation algorithm is the core of the spherical near-field test system. The general test optimizes the traditional near-far field transformation process. With the unique probe design, it creatively solves the three major challenges of vehicle OTA testing – large tested objects. The problem of eccentric near and far field of parts; the problem of effective probe illumination, cross polarization and symmetry; the problem of probe factor calibration in near and far field restoration. This enables accurate evaluation of vehicle wireless communication performance

Desense vehicle self-interference diagnosis

When the car is driving, various internal subsystems will affect each other, and the receiving sensitivity of the wireless communication system will be interfered by various noises, and all sensitivity-related tests can use the Desense interference test method. In order to accurately analyze the influence of each module in the car and improve the wireless communication performance of the car, Desense test has become a key indicator of the whole vehicle test.

Test items with Desense test:

  • Influence of vehicle status on various communication performance
  • Influence of in-vehicle equipment on various communication performance
  • Influence of vehicle power supply on various communication performance
  • Dynamic influence
EPP Rigid Foam Absorber

The absorbing material is one of the core components of the anechoic chamber, and its performance and product quality have a direct impact on the overall indicators of the project. The full range of general testing products adopts the high-performance, environmentally friendly fourth-generation absorbing material based on the world’s leading technology – general testing patented technology polypropylene foam (EPP) absorbing material, which has the unparalleled performance of traditional polyurethane sponge (PU) materials. Advantages: moisture-proof, flame-retardant, stable and environmentally friendly.

The manipulator is imported from Switzerland, industrial grade manipulator, which has been widely used in automobile, ship and aircraft manufacturing. High precision and reliability.

Test Software

Core Test automotive test software is independently developed by Universal Test to provide user-friendly result data display interface, including 3D/2D polar coordinates, 2D Cartesian coordinates, measurement data, raw data, test templates, etc. Covers a variety of measurement items including: passive antenna, 2G/3G/4G/5G SISO/MIMO, Wi-Fi, BT, V2X and GNSS. The software introduces a plug-in development model, and the underlying architecture is highly abstracted, making it easy to adapt to hardware changes. Can support a variety of instruments and match different templates, easy to operate and easy to use.

The template is linked and provides basic parameters, which reduces the complexity of the system and is convenient for users to use quickly. Supports custom task queue for unattended continuous testing. The raw data and logs are well managed, and the measurement process is fully traceable.

The software provides a dedicated automotive test data analysis and comparison software package, which supports the analysis and comparison of various test data on a common configuration computer, including:

  • Comparison of near-field test and far-field calculated data
  • Comparison of test data of different vehicles
  • Comparison of simulation data and measured data
  • 2D and 3D comparison from different angles
  • Multi-angle and multi-frequency data comparison
  • User-defined comparison