The latest test and measurement trends include Non-terrestrial and Open RAN networks
To set the stage for the Test and Measurement Forum (available on demand here), Emil Olbrich, vice president of network technologies with Signals Research Group (SRG), laid out some of the market trends his firm is tracking, particularly the complexities presented by Non-terrestrial networks (NTN) and Open RAN.
But, sitting above those particular technology categories, Olbrich said is “the biggest issue we see in the market…conformance versus performance testing…the real world versus the contrived. Being able to independently test and verify systems, I think, is very important.”
Whether for direct-to-device communications supported by a satellite constellation or for a disaggregated radio access network (RAN), he stressed the need to focus less on whether a particular set of technologies adhere to what’s laid out in the relevant standards and more on the end-user experience those technologies deliver.
Calling out the increasing adoption of artificial intelligence (AI) by network operators—a machination playing out faster than what’s reflected in standardization work—means a further disconnect between conformance testing and performance testing. “I think it’s tough to standardize innovation,” Olbrich said. Specific to the use of AI in mobile networks, “Do we see a net improvement in overall system efficiency or do you see better performance as an end user? That remains to be seen.”
Testing NTN
NTN is an area of growing interest with major operators engaging with satellite communications companies, specifically AT&T and AST SpaceMobile and T-Mobile US and SpaceX both working on satellite-enabled direct-to-device communications, and the U.S. Federal Communications Commission (FCC) taking up supplemental coverage from space (SCS) for extension of cellular coverage into rural areas. 3GPP standardization work on NTN began in 2017 with Release 15 and is ongoing.
Olbrich acknowledged this is a nascent area but also described a “back to the future” problem based on earlier satellite-based communications work done in the late 1990s and early 2000s by Globalstar and Iridium. Those challenges “don’t necessarily go away,” he said, going through link budget fading and signal-to-interference-plus-noise ratio (SINR), latency and timing synchronization, Doppler frequency synchronization, mobility and power management.
Another testing complication, he said, is around the variability in types of satellites and associated types of orbit–geostationary, geosynchronous or low-earth, as well as whether the goal is narrowband internet of things (NB-IoT), 4G or 5G communications. It’s an “exciting era,” Olbrich said. “As far as testing goes, there’s no shortage of testing because there’s a lot of different air interface technologies [and] implementations of it.”
Download this report, “The new space race: the outlook for NTN standardization and commercialization,” for a deep dive into NTN and other satellite/terrestrial networking topics.
Open RAN interoperability test and measurement
Examining growing operator investment in multi-vendor Open RAN, Olbrich started off by making clear that disaggregated radio systems are working in the real world today. “We’ve personally shown, from our organization, performance metrics that are on par with some of the best networks, even exceeding some of the best networks, in the world.” With the rise of Open RAN, he said, comes the need for testing interoperability between radio units, distributed units and centralized units from different suppliers.
Olbrich described “massive market demand” in this area but qualified that by calling back to his introductory commentary around conformance versus performance testing. “We don’t like to test interoperability. We expect things to work when we get them in the field, and we want to test performance.”
But given the realities of Open RAN interoperability testing, an increasingly automated process, he said, “This is going to be a continuing challenge.” He noted a bright spot in the U.S. Department of Commerce (DoC) announcing in January it would provide a $50 million grant to greenfield Open RAN operator DISH Wireless to establish the Open RAN Center for Integration and Deployment (ORCID). The idea is to host various Open RAN vendors and test interoperability between radio, distributed and centralized units using DISH’s commercial network.
Olbrich rightly noted that announced ORCID participants—Analog Devices, ARM, Cisco, Dell Technologies, Fujitsu, Intel, JMA Wireless Mavenir, NVIDIA, Qualcomm, Samsung and VMware by Broadcom—represent just a sampling of a much larger Open RAN vendor ecosystem. “I think the intention is good,” he said. “We’ll see what happens in reality.” As to the collaborative testing piece, “I think the market is seeing [and] the U.S. government is actually seeing value in that.”
Last test and measurement question for Olbrich: where should test and measurement vendors be focused? He gave the example of end-to-end testing for mobile gaming and extended reality (XR). “If you press a button on a game…how is that response…from when you touch a button until you get an action back on the server and get the response back. We can measure latency, but do we measure how fast the CPU and GPU on the phone are…all the way to the application server?…You have to take so much data from so many different nodes…Being able to do that end-to-end testing, but then delineate where the issues are, if we could see something like that that would help me do that, that would make my life much easier.”
