When you think about 5G cellular backhaul, fiber or microwave in rural or underdeveloped areas are probably the first technologies that spring to mind. But what about satellite?

According to Chris Antlitz, principal analyst at Technology Business Research, it’s not as crazy as it was just a few years ago.

Traditionally, satellite communications have been provided through a network of geostationary orbiters located high above the earth's surface. A geostationary earth orbit (GEO) allows a single orbiter to service a large portion of the earth's surface at any given time.

But at 22,000-plus miles above earth’s surface, the cost of global reach has traditionally been extremely high latencies — 550-plus milliseconds. And in the case of many aging satellite networks, it can be far worse than that.

What’s Changed?

So what’s changed that suddenly satellite communications is a viable option for a high-speed communications technology like 5G? If you ask Antlitz, a lot. In the span of two years, the technology has not only become viable but economically feasible as well.

One of the biggest changes is the cost of launching satellites into orbit has gotten a lot cheaper thanks to reusable boosters and launch vehicles from companies like SpaceX. Combined with a shift to smaller, lighter, and more technologically advanced low-earth orbit (LEO) and medium-earth orbit (MEO) satellite constellations, operators can now put more of them in orbit than ever.

To date, Starlink has launched about 1,500 LEO satellites with as many as 40,000 planned. Meanwhile, SES has 20 MEO satellites with 11 more advanced orbiters planned to launch over the next year.

“The LEO satellites are smaller form factors — way smaller than GEO satellites — and they can be more easily launched into the stratosphere,” Antlitz said. “The cost economics have fundamentally changed for satellite.”

Because these satellites are orbiting closer to the surface, the round trip between the user and a base station is considerably shorter.

Starlink’s constellation orbits at just 550 miles above the earth's surface. A lower orbit means lower latencies. A recent Ookla report found that Starlink can provide latencies as low as 45 milliseconds — that’s on par with 4G LTE today.

The lower orbit of LEO and MEO sats also enable satellite-to-satellite communications using a technology called phased array.

“It’s kind of a mesh network in space,” Antlitz explained. “They’re basically using microwave at altitude.”

In other words, instead of simply bouncing a signal off a satellite to a ground station, the signal can be relayed from satellite to satellite to reach any part of the world in only a handful of hops. And unlike terrestrial microwave networks, there aren’t any obstacles or weather to obstruct the signal, he said.

The result is a scenario where it’s conceivable for a satellite network to offer lower-latency communication between two geographically disparate locations. This is doubly true in developing regions with limited terrestrial infrastructure.

And this isn't just in theory, either. All three of the top cloud providers have announced new ground stations that will provide access to their cloud services anywhere in the world.

Last year, Microsoft Azure announced a partnership with SES and Starlink to serve emerging markets beyond the reach of traditional networks — think remote IoT, maritime vessels, oil, and gas.

What About Low-Latency 5G?

The one area that satellite communications won’t solve for is low-latency communications, and that’s okay, Antlitz said.

“Not every workload needs ultra-low latency,” he said. “When you’re doing accident avoidance or maybe drones in your airspace, for those types of use cases you need sub-10-millisecond latency to have good outcomes.”

For everything else, Satellite communication could be a viable option in the absence of fiber of microwave. And even still, latency requirements don’t immediately rule out the possibility of satellite backhaul, notes Karl Horne, VP of fixed data at SES.

“5G is more than just the next generation of radio technology, it's a huge architectural shift,” Horne said. “Some of the big tenants of that architectural shift is virtualization and distribution of functions.”

That’s because in order to achieve the low latencies that 5G promises, network operators are turning to edge compute, which in many cases eliminates the need to backhaul that traffic in the first place.

“Now we have an architectural template that allows us to put the right functions in the right place to deliver the right outcomes,” Horne said.

When satellite networking comes into play, he argues that it’s important to look at the end-to-end latency, not just the latency introduced by backhauling traffic to a satellite. He explained that if a satellite can provide connectivity over a single hop, the latency may be insignificant compared to sending that traffic over multiple terrestrial hops.

The Big Problem With Satellite

So if latency is quickly becoming a non-issue with satellite communication, what’s the catch? Space junk, argues Antlitz.

“The biggest problem, which doesn’t get talked about enough, is the space junk,” he said. “There’s too much crap floating around in space. The biggest issue they have logistically is making sure the satellites that go up in the constellations don’t get impacted by the space junk.”

This is because compared to GEO satellites, MEO and LEO sats are in relatively crowded orbits filled with other satellites and debris.

In a worst-case scenario, a piece of space junk could set off a chain reaction resulting in a phenomenon often referred to as Kessler syndrome. The scenario, first proposed by Nasa scientist Donald Kessler in the late ‘70s, describes a situation where a collision in orbit triggers a cascade of additional impacts, each generating more debris that eventually fills the orbit with an impenetrable field of shrapnel.

Long term: “They need to find a way to clear the space junk,” Antlitz said.

This scenario is further exacerbated by the fact there is only so much you can put in a given orbit, he explained. “There’s essentially a spacial land grab” for the ideal orbits.

Don’t Underestimate Satellite

While MEO and LEO constellations have a ways to go before they’re ready to take on the challenge of 5G backhaul — Starlink estimates it will have global coverage by the end of the year — it shouldn’t be underestimated, Antlitz argues.

“I think there is a faction of companies that underestimate satellite and they will be quick to say that it’s not a threat to their business,” he said. “I would not underestimate how much innovation is taking place in this sector.”