Panelists touched on 5G, Wi-Fi 7 and IoT non-terrestrial network devices
During a panel at the Test & Measurement Forum, two panelists discussed some of the testing challenges associated with next-generation devices, like those equipped with 5G and Wi-Fi 7, as well as communication satellites that will orbit the earth.
Tighter testing limits
According to LitePoint’s Product Manager Khushboo Kalyani, the biggest challenge facing the test and measurement folks at the moment is that the test limits are getting tighter. “Both 5G and Wi-Fi are two strong technologies; they are becoming feature rich,” she said, using Wi-Fi 7’s denser modulation scheme 4096-QAM and 320 megahertz channels as examples.
“In order to be able to achieve that higher data rate with such dense modulation, the EVM performance has to be extremely good, and the limits are getting tighter by the specs,” she continued. To measure wireless modulation, testing companies use a metric called Error Vector Magnitude, or EVM, which measures the deviation of actual transmissions from their ideal locations in the constellation diagram, capturing the sum of these imperfections to decipher a device’s transmit accuracy. In higher-order modulation, the constellation points are more susceptible to noise and non-linearities because they are closer together, making it more difficult to assess a device’s modulation and demodulation capability.
With limits so extreme, explained Kalyani, the test performance must have notable “headroom over the device’s performance” to make sure debt inaccuracies are not being masks and that signal quality is being ensured. Basically, in order to know if a Wi-Fi or 5G chip meets the requirements for transmitting and receiving the discrete phases of magnitude supported by the new standards, you need to have test equipment that can also meet these requirements.
Therefore, higher modularity requires more linear instrumentation, and Kalyani said this need for “extreme linearity” in the test equipment is the “biggest challenge.”
Challenges in space
Also on the panel was Thierry Berisot, the director of IoT/telecom, standards and spectrum at Novamint, which helps tech companies develop their innovations and R&D programs. He argued that there is a need for a certification for IoT non-terrestrial network (NTN) equipment.
The first IoT NTN devices are starting to enter the scene and are expected to launch commercially next year or so, but Berisot said there remains a lot of work around certifying these devices in the 3GPP standard. “The 3GPP perspective is… reflecting only IoT [from a] satellite perspective and not the fact that the device will support… both… cellular and satellite connectivity,” he continued, implying that the 3GPP might still consider satellite testing and certification to be outside of the cellular domain. “Therefore, one of the biggest challenges that we have is to develop [an existing] test case… to support this commercial launch… without [a] test case, there will be no commercial launch.”
Beyond the question of standards, Berisot also highlighted the challenge around supporting different satellite orbits. “GEO [Geostationary satellites] it’s quite easy, and in the standard, it was easy and from the measurement perspective it’s easy to integrate it, but it may not be adapted to all use cases…. [T]he support of LEO [Low-Earth Orbit satellites] is more challenging,” he said. For instance, LEO constellations have a high-rate Doppler effect that contributes to complex handovers, requiring greater complexity in the radio resource management (RRM) system. Further, LEO constellation scenarios necessitate several handovers per minute, leading to new scheduling issues.
“It’s… up to the device implementation but also to the test and measure [companies] to also integrate what is the support that will correspond, or all the test case that will correspond to the real commercial perspective that will be deployed in real life,” commented Berisot.
However, Kalyani pointed out that from an RF test perspective, the test process and items for IoT devices over NTNs “don’t really change much.” That’s because IoT NTN is going to be a “subset of whatever the physical LAN 5G features that [have]already been deployed,” she explained. “So, it’s going to be a subset, a smaller bandwidth… or smaller gigabit… so, from an RF perspective, the test process remains the same. The test items could be reduced because now the number of bandwidth combinations or the modulation scheme that you have to test is slightly lower versus the traditional mobile handset devices. So… the number of test items the test times will change. But other than that, I think the test aspect of testing transmitter, signal quality, receiver sensitivity, all those the specifics remains [sic] the same.”
Looking ahead, Berisot expects further integration of NTN and 5G, as well as with 6G. “You will have more complex architecture for satellite; you will have dual connectivity, real-time communication, more network selection aspect, more roaming between satellite[s], more high-frequency bond[s].” He added that by the time 6G comes around, this will be fully integrated and so you won’t think about satellite as a separate network from terrestrial cellular networks, but instead as just another way to connect.
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