Rohde & Schwarz showcases 5G NR OTA device testing
5G NR provides numerous technological advantages, but there will also be many technical challenges that need to be overcome during 5G NR testing. Since OTA measurements often require far field conditions in order to be carried out fast, easily and accurately, a high-quality quiet zone (QZ) is needed in which the wave fronts coming from a test antenna can be assumed to be plane. Larger QZs require a long distance between the device under test (DUT) and the test antenna, meaning large shielded chambers are needed in direct far field (DFF) setups. Conformance testing in the mmWave range also calls for black box testing, meaning the location and size of the antennas in OTA measurements are considered unknown.
To address the space constraints, Rohde & Schwarz employs the Compact Antenna Test Range (CATR) method, which has been approved by 3GPP. The method relies on indirect far field (IFF) technology to simulate far field conditions. The reflector used in a CATR setup transforms the incoming spherical wave front to a plane wave due to its parabolic shape. This requires extremely high precision in reflector manufacturing, with accuracy in the micrometer range. To achieve this high accuracy, Rohde & Schwarz has developed an innovative, fully automated manufacturing method, delivering considerably higher reproducibility than traditional, semi-automated processes.
Conformance testing is crucial in order to ensure that a device conforms to specifications, standards and regulations. In Barcelona, Rohde & Schwarz will premiere the ATS1800C, a fully anechoic mmWave CATR system and a turnkey high-end system for conformance and compliance testing. The ATS1800C uses IFF technology and provides a sophisticated, state-of-the-art RF test solution. The innovative manufacturing method for the reflector results in a high-quality QZ and therefore reproducible measurements. Unlike similar CATR systems on the market, the ATS1800C features a vertical layout, i.e., the positioner, feed antenna and reflector are arranged vertically, taking up only half the floor space and fitting next to a standard 19-inch rack.
Among the accessories available for the system is the T3O110 phantom series, including head and hands for 5G OTA, manufactured by the Swiss company SPEAG. These phantoms are based on a novel technology that replicates the layered structure of the human skin and simulates its RF properties up to 110 GHz. The phantoms are used to reproduce a realistic loading of the DUT and energy absorption of a human hand and head and are necessary to evaluate performance of the DUT in authentic use cases.
For general-purpose R&D testing, Rohde & Schwarz will introduce the ATS800R. This system uses a fully anechoic, compact shielding chamber accommodated inside a standard rack. The DUT can be positioned at an ergonomic height. The system also employs a high-grade, medium-sized CATR reflector delivering a QZ of optimal quality. This makes the ATS800R one of the most compact CATR systems for mmWave tests, providing a high-performance option for R&D measurements and optimally utilizing the available space by using a standard rack instead of a dedicated shielding chamber.
Thermal effects diagnostics on DUTs are crucial when analyzing chipset and UE performance since device heating or cooling can affect the RF components and consequently the radiation pattern of the antennas. Rohde & Schwarz has developed a setup that enables 3D RF measurements of antenna characteristics in a temperature range from –40 °C to +85 °C. Integrating the ATS TEMP climate option into an ATS1000 antenna test system makes it possible for the first time to combine testing in an RF OTA chamber and climatic chamber testing into a single procedure.
At MWC 2019, Rohde & Schwarz will exhibit a new system for testing large volumes of FR2 devices. The system consists of an CMP200 radio communication tester and an CMQ200 shielding cube. The CMP200 combines vector signal analyzer and ARB generator functionality. The 2 RU one-box-solution can be customized with up to three CMPHEAD30 remote radio heads (RRH) for up- and downconverting signals to 5G FR2 frequencies. The CMQ200 is a compact, flexible 19-inch shielding system that can accommodate most 5G devices in different applications.