March 19, 2018
Millimeter wave signals were more found to be more robust than expected and provided high speeds — although not gigabit speeds — at distances of several thousand feet from a node, Signals Research Group found in recent testing of Verizon’s 28 GHz fixed wireless access network in Houston.
“Millimeter wave signals are far more resilient than we expected, even at distances exceeding several thousand feet. Tree foliage, passing school buses, buildings, glass, and parked cars impacted the received signal, but the resultant signals were still capable of delivering meaningful data rates,” SRG concluded.
SRG believes the testing is the first independent industry testing of a 5G millimeter-wave network. In Houston, Verizon is using Samsung equipment and the 5G Technical Forum standard which was developed outside of 3GPP through the 5G TF group. (The carrier has said that it plans to migrate 5G TF to 5G New Radio.) SRG noted that “although the 5GTF specifications are not compatible with the 3GPP specifications, we believe the differences have immaterial impact on the metrics that we analyzed.” Analyst Emil Olbrich, who worked on the SRG testing, told RCR Wireless News that the testing focused more on performance of millimeter wave than on 5G NR-specific characteristics.
“As an engineer, I went in extremely skeptical of millimeter wave. I did not think, from a technical perspective, it was going to be very usable,” Olbrich said. “I came away very impressed, though.” He said that at a distance of about 4,000 feet, SRG was “still getting good numbers that could give you good data rates.”
SRG conducted stationary and walk-testing with a Rohde & Schwarz TSME drive-test scanner and omni-directional and horn antennas. With both antennas, SRG said, it “tested at distances that greatly exceeded operator public statements that we’ve heard.” However, even though data rates were very good in many locations — on the order of 300 Mbps to 500 Mbps — that doesn’t quite live up to Verizon’s intent to provide gigabit speeds, Olbrich noted. SRG concluded that “promising gigabit data speeds to all homes may prove to be challenging, especially in the near-term.”
SRG outlined its test methodology — including a few experiments to explore how well millimeter wave signals could be received in tricky, non-line-of-sight scenarios — in this video. Olbrich said that testing 5G networks in the field is a much different experience than testing LTE networks.
“How we test and measure in the field is going to look very different than what we did in the past,” he said. “There’ll be some similarities — the metrics and KPIs will be similar — but now we’re looking at individual beams and how they’re manipulated in the network, and how much data is given to each user, and how you can re-use signals from the same sector in different beams. … It’s a new experience for those testing it like ourselves.”