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Loon and Terrestrial LTE can Co-exist

In our last post we looked at how Telstra and Ericsson have increased the distance of LTE cell from 100 km to 200 km. If you compare that to Google Loon or other HAPS that fly at 20 km above earth (details here), it should be an easy task. This is what Signals Research Group investigated as part of their report which is available here officially or on LinkedIn here, unofficially (or officially as well).
Fierce Wireless has a good summary of this report here and extract reproduced below:

Based on a study of Loon’s network in Peru, Signals Research Group (SRG) found that Loon has a “modest” detrimental impact on the existing terrestrial LTE network while improving coverage in areas where terrestrial LTE coverage doesn’t exist. It’s pretty much the same impact one would get from any cell site being introduced in the same area.

Any time a new cell site gets deployed in an LTE network, it will generate at least some interference with adjacent cells, and Loon, whose balloons fly more than 60,000 feet above the earth, is no different, the research firm said.

SRG conducted the study—which was sponsored by Loon—the last week of September in a region just south of Tarapoto, Peru. The analysis involved both drive and walk tests and a mix of smartphones, with scanner equipment provided by Rohde & Schwarz and test solutions from Accuver America.

“The upshot is it does exactly what it was targeted to do,” providing a basic means to connect to mobile data in areas of the world that don’t have terrestrial coverage, and when it does that, its impact is very modest on the terrestrial infrastructure that exists there, said Mike Thelander, president of SRG, who posted a short video on LinkedIn.

“I think there may be some concern perhaps from some operators that ‘you’re going to put these balloons overhead, and all they’re going to do is mess up my network,’ and that doesn’t happen,” he told FierceWirelessTech.

On the user end of the service, consumers can do anything with a Loon-serviced device that LTE can do; there’s no VoLTE for voice calls, but over-the-top apps like Skype work just fine, he said. It’s not the kind of user experience you’d get in a place like downtown Seoul by any means, but “it is quite good,” he said.

According to SRG, the performance of the Loon network is somewhat comparable to a terrestrial LTE network. The Loon network that it tested used a 2x10 MHz channel in Band 28, so comparisons with a terrestrial LTE network need to be made accordingly.

“Although we observed sustained data speeds in the high teens (Mbps) and a peak physical layer throughput that was just over 40 Mbps… we believe more typical data speeds with Loon are in the mid- to high- single digits,” the executive summary states. “Latency was also only modestly higher (13%) than the terrestrial LTE network.”

Loon’s balloons act like floating cell towers, transmitting a provider’s service directly to a subscriber’s LTE device below. Loon’s balloons actually receive a signal from the ground, which is then shared across multiple balloons that spread it to users below using standard LTE signals.

The SRG study was intended to look at the interaction between Loon and terrestrial networks, according to Loon spokesman Scott Coriell. Loon needs to partner with a local carrier in any given location in order for it to work.

“Our aim is to help these local carriers expand their networks to places where it was previously difficult or impractical, and to help them attract new customers or better serve existing ones,” Coriell said, adding that Loon is pleased with the study’s findings.

Currently, Loon has two deployments planned with partners in Kenya and Peru, and it’s in conversations with other mobile operators around the world, he said. Loon has a lot of experience flying above the U.S., and there are use cases where Loon could help expand service in the U.S. It has provided services in Puerto Rico, but it hasn’t announced anything commercial-wise in the contiguous U.S.

Loon came into limelight when it was used to provide emergency coverage to Puerto Ricans picking up the pieces after Hurricane Maria back in 2019.

While this was hailed as a success by many, the results indicated that it was not a smooth sailing.

While these experiments prove that technically it is possible for Loon and terrestrial LTE to co-exist, there are still operational challenges that would need to be solved for Loon and other HAPS solution to provide a coverage in time of need.

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