Starlink Vs. Physics. Can Cell Towers In Space Reach Devices Indoors?

SpaceX’s satellite-to-phone service Starlink Mobile was designed to eliminate cellular dead zones in rural and remote areas. But is it powerful enough to penetrate steel and concrete?

Executives at traditional wireless carriers are suggesting that SpaceX is unlikely to put them out of business for one big reason: Starlink signals will struggle to reach people indoors.

The CEO of T-Mobile, a SpaceX partner, subtly suggested he doesn’t view Starlink Mobile as a threat. In a talk at a Morgan Stanley technology conference this week, Srini Gopalan noted that he and SpaceX executives view Starlink Mobile as “far more complementary than…substitutional just because the physics and the economics of it worked that way.”

“Whether you think of the kind of the beam that you have in a satellite, whether you think about the ability to connect indoors, it’s a clearly complementary category,” he added.

T-Mobile CEO Srini Gopalan (Credit: Michael Nagle/Bloomberg via Getty Images)

At Mobile World Congress this week, current and former executives from Nokia, AT&T, and Samsung also told Fierce Network they don’t expect SpaceX’s satellites to offer strong coverage inside buildings or in denser urban environments. “It’s just physics, right? I think it’s difficult. Our current technology does not allow it for the foreseeable future,” said Woojune Kim, Samsung’s president for its networking business.

The “physics” of indoor coverage also means users shouldn’t expect Starlink Mobile to ever match the building penetration or network capacity of traditional terrestrial towers, which may require using indoor cell signal boosters.

SpaceX brought up the limitation in its own MWC keynote. Although CEO Elon Musk entertained the idea of turning Starlink into a traditional carrier during a September podcast appearance, executives at MWC pitched partnerships over rivalry.

“Satellite is complementary to terrestrial networks; it cannot provide the data density that terrestrial networks have. But it can augment terrestrial networks in the places where terrestrial networks cannot reach. Or when terrestrial networks need additional capacity,” said Michael Nicolls, SpaceX’s VP for Satellite Engineering.

Starlink Mobile

Michael Nicolls, SVP for Starlink at SpaceX (Credit: Angel Garcia/Bloomberg via Getty Images)

Still, the company is planning major upgrades to Starlink Mobile in 2027 that promise to unleash 5G speeds, with download rates up to 150Mbps per user. So we’ll be curious to see whether the improvements translate to any indoor coverage.

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The current version of Starlink Mobile—which T-Mobile offers as T-Satellite—can work inside a car, as our testing found last year. That’s probably because the satellite signals can easily penetrate car windows. However, the connectivity seemed to immediately drop once our phone moved under tree cover. One report from last year estimates that Starlink Mobile currently offers speeds at around 4Mbps.

To improve performance, SpaceX plans to build a new constellation of up to 15,000 satellites, designed to harness even more radio spectrum acquired from Boost Mobile’s parent, EchoStar.

Interestingly, the company’s plan doesn’t rule out using traditional cell towers to bolster the connectivity either. “SpaceX may deploy ground-based systems in the US, creating a hybrid satellite/terrestrial network to expand the coverage and capacity of these services,” the company told the Federal Communications Commission in September.