5G Millimeter-Wave devices: testing what matters

5G testing challengesKeysight Technologies, the world’s #1 test and measurement company, is playing a major role in developing 5G testing equipment for the global telecom industry.

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5G testing business will receive a boom because many device manufacturing firms such as Asus, Fujitsu, Fujitsu Connected Technologies, HMD Global, HTC, Novatel Wireless, LG, NetComm Wireless, NETGEAR, OnePlus, OPPO, Sharp, Sierra Wireless, Sony Mobile, Telit, vivo, Wingtech, WNC, Xiaomi and ZTE are expected to launch their 5G devices in 2019.

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These OEMs are working with chipset company Qualcomm Technologies to commercialize 5G mobile devices for the sub-6 GHz and millimeter wave (mmWave) spectrum bands starting in 2019 based on the Snapdragon X50 5G NR modem.

Alex Katouzian, senior vice president and general manager, mobile, Qualcomm Technologies, said: “We are utilizing our expertise and technology leadership to support the launch of 5G NR, driving innovation in the mobile ecosystem.”

Keysight Technologies said the goal to deploy 5G in the 2020 timeframe demands mmWave over-the-air (OTA) test solutions and requirements in little more than half the time taken to develop the basic 4G MIMO OTA test methods.

“The emergence of 5G mobile communications is set to revolutionize everything we know about the design, testing, and operation of cellular systems,” said Girish Baliga, marketing manager — Wireless, Digital & Aerospace Defense test at Keysight Technologies.

5G testing to boom

Several industry analyst reports suggest that there will be 1 billion 5G subscriptions and 8x mobile data traffic growth by the end of 2023 putting pressure on mobile operators’ data networks. Device makers need to invest in advanced 5G testing solutions to meet consumer and enterprise demand for applications such as 4K/8K video streaming, virtual reality/augmented reality, and immersive media.

First, a bit of background on the move from cabled to radiated testing, and then we will discuss the three main areas of testing that we’re going to have to deal with: RF test, demodulation test, and radio resource management.

Millimeter-wave devices with massive antenna arrays cannot be tested using cables because there will be no possibility to add connectors for every antenna element. The dynamic (active) nature of antenna arrays means it isn’t possible to extrapolate end-to-end performance from measurements of individual antenna elements. It’s time to throw away the cables for testing 5G.

A new radio design starts with the reality of the deployment environment, in this case a mmWave one. Next, we model the radio channel and once we have a model, we can design a new radio specification to fit the model. Then, we design products to meet the new radio specifications, and finally we test those products against our starting assumptions in the model.

If the model is sufficiently overlapped with reality—then products that pass the tests should work when they are deployed in the real environment. That’s the theory.

This process works well at low frequencies. For mmWave, however, there is a big step up as the difference in the propagation conditions is enormous, Keysight Technologies said.

Now let’s look at the categories of radio requirements that we’re going to have to measure—that is, what we measure and the environments we measure them in.

For RF, it’s about what is already familiar—power signal quality, sensitivity—and those are all measured in an ideal line-of-sight channel.

With regards to demodulation, throughput tests will be done in non-ideal (faded) conditions as was the case for LTE MIMO OTA. There we had 2D spatial channels, but for mmWave, the requirement will be 3D spatial channels because the 2D assumptions at low frequencies are no longer accurate enough.

Radio resource management (RRM) requirements are about signal acquisition and channel-state information (CSI) reporting, signal tracking, handover, etc. That environment is even more complicated because now we’ll have a dynamic multi-signal 3D environment unlike the static geometry we have for the demodulation tests.

5G opportunities and challenges

The benefits of 5G and mmWave have been well publicized. There’s a lot of spectrum that will allow higher network capacity and data rates, and we can exploit the spatial domain and get better efficiencies. However, testing all of this has to be done over the air and that presents a number of challenges that we have to solve if we’re going to have satisfied 5G customers.

We know that we’re going to have to use active antennas on the devices in base stations, and those are hard to deal with. We know that spatial tests are slower than cabled, so you can expect long test times.

We’ve got the whole issue of head, hand, body blocking on devices—it’s something that isn’t being considered for release-15 within 3GPP but will still impact customer experience.

OTA testing requires large chambers and is expensive. We know OTA accuracy is not as good as cabled testing—we’re going to have to get used to that. Channel models for demodulation and RRM tests haven’t been agreed upon yet, which is impacting agreement on baseline test methods for demodulation and RRM.


There’s a paradigm shift going on because of mmWave. We used to work below 6 GHz and the question we asked at < 6 GHz frequencies was, “How good is my signal?” That question led to the development of non-spatial conducted requirements. The question now for mmWave is, “Where is my signal?” That’s going to lead to the development of 3D spatial requirements and OTA testing. This is a fundamental shift in the industry. It’s going to be a tall order…testing 5G mmWave devices.