LEO Advances on the Ground

Antenna and gateway technology will play a crucial role as the industry moves into the LEO era.

2020 is set to be the year of Low-Earth Orbit (LEO) as more providers build out their business cases and constellations for operating in LEO, a market that promises to deliver cost-effective, high-throughput connectivity and low latency to global users.

According to Northern Sky Research (NSR), wholesale operator revenue from non-geostationary constellations is expected to post a compound annual growth rate of more than 40% during the next decade.

Even as early LEO entrant LeoSat suspended operations after funding from operators in Spain and Japan fell through, the industry remains bullish on the future of the LEO market. Many in the industry share the widespread view that this new generation of low-cost, high-throughput networks will be part of the satellite landscape sooner rather than later.

In order to be successful, LEO providers need the ground segment to offer simpler, more integrated solutions at a lower cost. Here, Via Satellite talks to a handful of ground segment players about the crucial role antenna and gateway technology will have as the industry prepares for the coming LEO era.

“It’s about integration, industrialization, and reduction of cost,” observes Kirby Nell, director of LEO products for Cobham Satcom, a satellite and radio communication terminals provider with a dominant position in the maritime market. “Service providers now are pushing us towards integration.”

A typical Geostationary Orbit (GEO) ground segment in the past featured distributed equipment – an antenna, interconnected RF and IF cables, a base station, and networking equipment — but no more. High Throughput Satellite (HTS) networks, especially those supporting LEO constellations, will integrate this technology into the user terminal.

Nell points to ViaSat-2, which launched in 2017 to provide high-capacity broadband service, which has integrated the modulator and all the networking functions in the antenna. “It’s to drive down costs – to make the installations cheaper and easier, to make the subscriber-acquisition costs drop,” he explains.

The same driver will apply to the LEO ground segment. LEO operators are looking at different aspects of the market, from backhaul IoT applications, to consumer broadband internet, to the enterprise and “very high” enterprise market.

Cost as the Common Driver

“Each of the constellations is different – not only in frequency, but also in the way they are addressing the business,” says Bill Milroy, chairman and CEO of ThinKom Solutions, a satellite system supplier serving both commercial and government ground segments. “But no matter which LEO go-to-market strategy companies are pursuing — across the board — everyone is cost sensitive,” he says.

Cobham Sea Tel antenna

Because the market is so cost-driven, it’s important that companies don’t provide any more performance than absolutely necessary. “The key is to make the antennas and other ground systems as easy and as inexpensive as possible to install and manage,” Milroy says.

User terminals serving LEO constellations must accommodate a tremendous amount of switching from beam to beam, and satellite to satellite.

Amir Yafe, head of Global Accounts for Gilat Satellite Networks, notes that LEOs will require an “order-of-magnitude increase in the number of gateways and a two-orders-of-magnitude increase in the number of gateway antennas.”

“The whole system requires a fair degree of sophistication and computing power that’s going to accommodate all this switching,” says Dave Rehbehn, vice president of International at Hughes, which operates the Jupiter System VSAT platform.

“People want to see 25-megabit service plans and soon-to-be 100-megabit service plans,” Rehbehn says. “Operators want to get the maximum amount of efficiency from the ground system because even with a 500-plus gigabit satellite with our Jupiter-3 that we’ll be launching in 2021, we still want to eke out as much capacity utilization as possible, so efficiency is important.”

Rehbehn points to two key challenges facing the ground segment: accommodating the hand offs, and handling the complexity of knowing where satellites are at any one point in time to effectively manage satellite resource capacity. Hughes has already shipped the first gateways for OneWeb’s 650-satellite constellation. “One of the key metrics for these gateways is that each gateway is capable of 10,000 handoffs per second – many more handoffs than what’s experienced in a typical terrestrial/cellular base station,” Rehbehn says.

Race for a New Kind of Steerable Antenna

Rehbehn and other ground segment players agree that LEO constellations will need cheap, electronically steered antennas that can seamlessly switch from one satellite to another as they move across the sky.

Operators have options in the early days of deployment: they can initially use mechanically steered parabolic antennas or the currently available, but more expensive, electronically steerable antennas until the new market-disruptive, low-cost solutions deploy.

Several ground system providers believe mechanically steerable antennas still can play a key role in LEO constellations. Cobham Satcom, for example, is pursuing electronically steerable antenna product development, while leveraging its maritime experience to offer mechanically steerable antennas to the LEO market. “There’s this perception – and it’s the wrong perception – that mechanically steered antennas are going to fail. We have 30 years of maritime field data that demonstrate to customers that our antennas just don’t fail,” Nell says.

Nell explains Cobham is currently looking to adapt its maritime antenna for the LEO market. “We’ve got to find the fine line between reliability and cost,” he says.

Electronically steerable arrays are ideal for terminals from 60 centimeters and down. However, “once you get above 70 centimeters, the mechanically steered parabolic antennas have the performance advantage over steerable arrays,” he says.

Advances in Pointing Accuracy

Cobham has built an E-band tracking antenna at one meter that offers “one hundred of degree of pointing accuracy when tracking a moving object.”

“In the GEO/Ka-band space, you can be mis-pointed by as much as .1 or .2 degree. We have had to improve our pointing to be 10 times more accurate. We were able to do that quickly because of our maritime heritage,” Nell says.

ThinKom is another company that sees value in taking their proven GEO products, with minimal modification, to LEO operators. The company, whose fuselage-mounted Ku-band antennas systems power GoGo’s in-flight broadband internet service, is currently developing fixed terminal solutions for LEO and Medium-Earth Orbit (MEO) constellations, working closely with Telesat and SES on their LEO and MEO networks.

Milroy says airlines have responded well to ThinKom’s approach of offering GEO antennas that are also LEO and MEO capable, in contrast to many competitors in the aeronautical space looking to provide LEO-only solutions.

“Our approach has resonated really well with airlines – they don’t want equipment that only works on a LEO or MEO constellation. We’ve not seen anyone willing to abandon GEO capability for LEO,” says Milroy. “We like to call our solution a no-compromise solution. You’re getting best-in-class GEO capability in terms of throughput and spectral efficiency, and with all the agility and flexibility to fully exploit LEOs and MEOs.”

Milroy says ThinKom’s 10-centimeter-high antennas use up to 90% less power than traditional electronic phased arrays.

Proven LEO-Ready Modem Technology

Beyond antennae technology, modem hardware also plays an important role. Hughes, a modem and ground system provider, has already begun shipping gateway systems for OneWeb.

OneWeb Gateway from Hughes

In September, several companies, including Hughes and ThinKom, demonstrated the first-ever inflight roaming tests on SES’s GEO and O3b MEO satellites in a test flights from South Florida to the Caribbean Sea. The in-flight demo used a Hughes’ Jupiter System and a Hughes ModMan modem, integrated to the ThinKom Ka2517 phased array airborne antenna mounted on a Gulfstream G-III test aircraft.

“In the course of this flight, the modem switched from SES GEO satellite to the SES O3b satellites and back many times in a near-flawless manner in addition to being able to perform the switching from GEO to MEO and MEO to GEO,” recalls Rehbehn, noting that the companies also demonstrated 265 megabits of throughput to the aircraft. “From a modem technology perspective, we understand how to do it and we have a high degree of confidence in the technology.”

Gilat, another leader in modem technology, has tested its modems in aero and maritime environments, as well as 5G connectivity over Telesat's Phase-1 LEO satellite. In 2018, the company’s modem helped demonstrate seamless connectivity and switchover between Telesat’s GEO orbit and LEO satellites. This past May, the Israeli-based satellite networking firm successfully demonstrated 5G connectivity over a LEO satellite. The test, conducted by a tier-1 European operator at the 5G Innovation Centre at the University of Surrey in the U.K., demonstrated 5G backhauling over LEO with Gilat's modem.

“We are also revolutionizing our modem technology to deliver gigabit services,” says Gilat’s Yafe. Without question, the LEO market is driving an increase in bandwidth requirements for the ground network – and much wider spectrum use.

John Golding, product manager with ViaLite, a satcom RF-over-fiber equipment provider, says one of the main expectations from LEO operators is for ground-segment systems equipment to be “more reliable for longer periods of time.”

“We’re excellent at long distance, especially diverse links where you may have two ground station antennas in very different geographic locations hundreds of miles apart. ViaLite is able to maintain wide bandwidth connections at high frequencies for long distances, up to 600 km, over fiber,” he says.

The LEO constellations require more network planning because operators must manage a whole constellation or network of teleport sites around the world. “There’s a lot more to monitor so management resources have to scale easily,” Golding explains.

ViaLite system designer tool

To increase the reliability and maintainability of supporting a LEO ground segment installation, ViaLite has developed a System Designer tool. It gives LEO and other operators the ability to visualize the performance characteristics of their RF-over-fiber links within their network. The tool lets operators design a new system or recreate their own, and analyze its performance results to show where improvements can be made. The company also offers an RF-over-fiber system controller card, Horizons, which records the configuration of each slot within a ViaLite chassis. This allows operators to quick hot swap cards, which are then automatically reprogrammed, providing service recovery within half a second of the card being replaced.

“We have a history of trustworthy products, which lends us well to the LEO constellations where the ground segment needs to be ultra-reliable. Even if LEO satellites experience higher failure rates versus GEO, the ground segment can remain a dependable and steadfast element,” he says.

Upbeat on LEO’s Future

Ground segment innovators remain upbeat on the future – with many agreeing that questions remain, including in areas of regulation, as well as the LEO operators making their specific business case.

Even with that uncertainty, ground providers remain confident that both LEO and MEO constellations will become a reality soon and will significantly expand the satellite sector by offering plentiful bandwidth at lower latency than what’s available today.

Gilat Satellite Network headquarters in Petah Tikva, Israel

“We believe that the LEO market will start with premium applications and with terminal cost reduction eventually will become widespread – providing solutions for a large variety of applications,” Gilat’s Yafe predicts.

What must the satellite industry get right in the next 6 to 12 months? Cobham’s Nell says the true cost driver will center on the spacecraft, not the ground segment.

“It’s all around the business model. Can you put together a business model where you need 300 or 3,000 satellites, launch them all, put in all the infrastructure you need, and still have a viable business case? It’s going to be about driving costs out of the most expensive part of the system – the satellites.”

Crossed Signals: LEO & Antenna Interference

As the many LEO players’ megaconstellations come closer to reality, one question continues to come up — How to control antenna interference between other satellites, not to mention radio astronomers who already are struggling to perform their Earth-observation activities as the Earth becomes ever “noisier”?

Established satellite players have long had to grapple with the question of signal interference, but the LEO networks promise much more complexity and potential for crossed signals. The antennas are smaller, but they also have higher side-lobe gain, increasing the likelihood of interference from their operational power requirements.

“We do a very good job of focusing the energy into the main beam with very little energy going in other directions,” notes Bill Milroy, chairman of ThinKom Solutions. “Now the quality of the antenna patterns on the transmit and receive side is suddenly getting a lot more scrutiny from the regulatory agencies. What you used to be able to get away with has become a bigger challenge because you’re worried about jamming your own satellites or you may be jamming a competitor’s.”

According to Milroy, antenna sidelobes and regulatory masks are getting renewed focus, particularly by regulatory groups, and now with terrestrial 5G users moving to the same frequency bands as satellite users, it’s getting very “crowded” out there.

“It’s a big issue across the board,” he says. “A lot of our competitors – particularly the electronically scanned competitors – are a little behind us in terms of development … I don’t think they’ve really addressed regulatory requirements yet.” VS

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