Verifying O-RAN radio units that support M-MIMO beamform topics
Wireless communications | Massive MIMO beamforming testing
Author: Sanna Brandt, Market Segment Manager Wireless communications, Rohde & Schwarz
Comprehensive open RAN (O-RAN) WG4 conformance testing with massive MIMO (M-MIMO) beamforming support: When the O-RAN radio unit supports M-MIMO with beamforming downlink and uplink, the scope of WG4 conformance testing must be broadened.
Beamforming measurement with the R&S®VSE vector signal explorer software displaying EVM, phase and amplitude for each antenna port
Our O-RU test solution
Rohde & Schwarz is working with VIAVI Solutions to offer a powerful O-RU validation solution that supports M-MIMO with beamforming. The solution is in line with O-RAN ALLIANCE WG4.CONF and verifies that an O-RU can transmit a basic 3GPP test frame with predefined spatial beams. Comprehensive O-RU testing is possible – from functional verification and conformance to performance validation. The solution supports all beamforming variants, offering the broadest coverage on the market.
Existing O-RU tester users can easily upgrade a setup by adding a phase shift matrix (PSM) and an R&S®RTO oscilloscope to test M-MIMO with beamforming. The simple upgrade lets users maximize their test investments.
The VIAVI TM500 O-RU Tester (O-DU emulator) synchronizes and configures the O-RU under test. A Rohde & Schwarz signal generator, such as the R&S®SMW200A vector signal generator, provides the RF signals and waveforms, while a signal and spectrum analyzer such as the FSW signal and spectrum analyzer captures transmitted signals and analyzes I/Q data in the uplink and downlink.
By adding an R&S®RTO oscilloscope and connecting a PSM to the M-MIMO antenna ports on the O-RU, you can sequentially measure both downlink and uplink beamforming:
The whole test setup is fully automated and controlled by the O-RU Test Manager Application (O-TMA) from VIAVI to simplify O-RU conformance testing. Select the test case you want to run, and the test manager automatically triggers the configurations, runs the test case and provides a test report.
Once the test setup is configured, DL measurements start with the O-DU emulator inserting beam ID information into the I/Q packets and sending them over the open fronthaul (O-FH) interface to the O-RU.
After receiving and decoding the I/Q data stream, the O-RU reconstructs the waveform and transmits the RF signal over its antenna array. The signal is routed through the PSM to the R&S®RTO oscilloscope, where it is captured for analysis. Measurements are first taken across all antenna ports, followed by detailed evaluations of ports 2 through to the highest number supported by the O-RU (16, 32 or 64). The captured data is processed with R&S®VSE software and checked using predefined pass/fail thresholds.
Once all ports are measured, the system automatically generates result logs and summary files, with final values presented in a convenient table. If any antenna port exceeds the limits set by the test engineer, the test is flagged as a failure.
For uplink testing, the R&S®SMW200A vector signal generator creates the UL signal and feeds it into the PSM, which forms the matching uplink beam to the O-RU. The O-RU processes the received signal, and the resulting I/Q data is captured and analyzed by the TM500 O-RU Tester. The VIAVI O-TMA then provides a clear pass/fail report for all test results.
Beamforming measurement with the R&S®VSE vector signal explorer software displaying EVM, phase and amplitude for each antenna port
Summary
This fully integrated and automated test solution from Rohde & Schwarz and VIAVI Solutions complies with O-RAN ALLIANCE WG4 and 3GPP specifications for reliable validation of O-RUs with M-MIMO beamforming. The test solution supports all beamforming variants and provides comprehensive compliance reports for both downlink and uplink.
The setup is future-proof and can scale up or down to meet evolving standards. A key advantage is reusability: existing O-RU testers are easy to upgrade, without adding separate systems or duplicating equipment. The automated control and detailed result logging in the solution streamline conformance testing and accelerate certification processes.
Test setup for O-RU M-MIMO with beamforming verification:
Featured products for O-RU M-MIMO with beamforming verification
