NI Semiconductor Marketing Director Discusses Challenges of 5G Millimeter Wave Testing

Recently, David Hall, director of semiconductor marketing at National Instruments (NI), was interviewed by Electronics Media. He shared his insights on mmWave-related test challenges, mmWave beamforming, and related field research on characterization and verification of 5G testing.

David Hall, Director of Semiconductor Marketing at National Instruments (NI)

What are the main challenges that must be faced when deploying 5G using mmWave and other available solutions?

5G deployments in frequency range 2 (FR2), or 24 to 40 GHz, present considerable technical challenges compared to sub-6 GHz or FR1 deployments. The circuit level and OTA of signals at mmWave frequencies are very different from lower frequencies, from the chip level all the way to the network level. mmWave components such as power amplifiers and transceivers have not historically faced the challenges of being used in mobile devices, so efficiency, footprint, bandwidth and even linearity requirements are different.

Of course, one of the most obvious system-level challenges in deploying mmWave systems is signal propagation, and while techniques such as beamforming can improve the received signal strength of mobile devices, it mainly solves the problem of connecting the base station and the mobile device.

Another major challenge for 5G mmWave deployment is to manufacture and test these devices while also keeping costs down. The market demand for mmWave systems in mobile handsets is likely to be an order of magnitude higher than the demand for 4G devices. The industry is desperately looking for cost-effective solutions to help them test a large number of highly integrated and complex mmWave devices, such as antenna-in-package (AiP), in a shorter time.

What are the challenges of mmWave testing in the consumer space?

Testing mmWave devices requires significant innovation in both the test equipment itself and engineers’ test techniques. Taking production test as an example, traditional mmWave test equipment is primarily designed for aerospace/defense applications such as radar and satellite communications testing, which is inconsistent with the price point, performance, and footprint required for large-scale commercial technologies such as 5G. In the consumer space, the test equipment required for 5G mmWave components requires wider instantaneous bandwidth, higher dynamic range, and faster measurement speeds than traditional solutions. This is one of the driving factors that NI equipment can accelerate and optimize mmWave testing in a modular way. Is

beamforming more important in the 5G era than in the 4G era? Why is it so important?

Beamforming is critical in mmWave due to the propagation characteristics of these high-frequency signals. Using a combination of analog and digital beamforming techniques, base stations are able to transmit downlink signals to end users with higher receive strength, and user devices can correctly focus their beams to the base station, making them more efficient. The use of beamforming ultimately extends the operating range and increases data rates by using higher-order modulation schemes and lower bit error rates.

What is beamforming characterization and beamforming validation testing? How does it work?

Characterizing the beamforming capabilities of a mmWave radio requires over-the-air (OTA) testing. In a typical test setup, the radio is placed on a 3D gimbal in a darkroom. Using an RF signal analyzer connected to a static receive antenna inside the chamber, the radio is configured to transmit an uplink signal in a specific beam pattern. To characterize this beam pattern, the RF signal analyzer takes a series of RF power measurements while rotating the device under test.

By scanning the device in azimuth and elevation, engineers can obtain a 3D antenna pattern for the device under test. In this implementation, one of the historical limitations of characterizing beamforming devices has been keeping the RF signal analyzer synchronized with the movement of the DUT positioner while keeping the time as short as possible. One of NI’s recent innovations in beamforming testing leverages the power of the PXI platform to more tightly synchronize these components, resulting in faster measurement results.

Learn more about NI’s 5G test solutions for sub-6GHz bands

For 5G devices below 6 GHz, NI provides a full range of test solutions from R&D labs to production lines. For verification testing, NI's vector signal transceiver (VST) provides up to 1 GHz of instantaneous bandwidth to test components such as RF front-end modules (FEMs) and transceivers. Taking advantage of the high bandwidth, engineers can also use NI's digital pre-distortion software (DPD) to test RF FEMs under linearized conditions. In typical device characterization scenarios, the speed of NI solutions enables engineers to significantly reduce the test time of engineering samples, thereby shortening the product launch cycle.

For production testing, NI's Semiconductor Test System (STS) provides industry-leading measurement throughput and accuracy. Using this system, engineers are able to perform parallel testing of FEMs designed for user equipment (UE) and base station applications. With the measurement speed advantage of PXI, typical STS users are able to increase test throughput by 20% to 50% when using STS instead of traditional ATE systems.

What is NI's latest research on 5G advanced communication systems? What services are provided?

One of the most important research areas for 5G testing is the OTA testing field. Although lab-based OTA test systems have become quite common - the methods used in lab environments cannot meet the cost and speed required for mass production. Therefore, NI continues to study near-field and far-field methods for OTA testing in preparation for providing OTA-based manufacturing test solutions in the future.