There are many factors driving the ballooning complexity of ground systems, but paradoxically one of them is the customer desire for simplicity.
“We're at a position in the market where customers want simplified satellite services,” Jon Sala, Eutelsat vice president of Products, Platforms and Connectivity said during the session “The Hidden Complexities of Ground Systems,” on Tuesday during the SATELLITE 2021 conference.
But providing that simplicity in a multi-orbit world is complicated — it means providing connectivity from satellites moving across the sky using multiple different frequencies and waveforms. For satellite operators, he explained, it means figuring out “how do we integrate multiple [Network Management Systems] NMS technologies into something that's simplified as a common portfolio for customers? How do we stitch together an ecosystem that can be accessed by customers on demand?”
The objective, Sala said, is ground services that can be rolled out for a customer as quickly and easily as cloud computing services can be provisioned. He acknowledged that satellite operators have lagged cloud providers by a decade and are now catching up, but still a couple of years behind.
Physics, and the characteristics of the various frequencies and waveforms used by satellite systems also drive complexity, said Channasandra Ravishankar, senior vice president of Engineering for Hughes Network Systems. The new generation of high throughput satellites can handle 500 Gbps, but that creates technical challenges on the ground. “How do you push that many bits to the satellite over a limited amount of spectrum?” Ravishankar asked.
Traditional frequency bands like Ka-band provide limited bandwidth and require a large number of gateways, increasing the complexity of the ground system. Stepping up to higher frequencies, like the Extremely High Frequency (EHF) Q- and V-bands, reduces the number of gateways required for bandwidth, but bring other issues, he said.
Using EHF bands means “availability is a big question because weather affects the signal propagation,” Ravishankar explained. Alternate gateways, or diversity gateways, are required to ensure that if one was impacted by rain fade, another could be used instead. “I went to a higher band in order to reduce the number of gateways, but now to get the same availability, I need more gateways to use as diversity gateways in order to get availability during adverse weather.”
Moreover, he continued, “The moment I start using a diversity gateway then I need a routing mechanism to take packets coming from the internet allotted to an operational gateway and redirect them to the diversity gateway and I need a queuing mechanism to ensure the packets arrive in order.”
Also required: An algorithm that can predict rain fade and reroute the signal ahead of time, before it happens, to avoid packet loss and dropped connections.
“You can imagine the devil is in the details,” Ravishankar observed dryly.
All of this complexity, Ravishankar concluded, is ultimately driven by the needs of the customer. “At the end of the day, the quality of experience of the end user is paramount. Just because there's rain, just because we're using the band we are, we don't want the end user to suffer.”
Higher bandwidth demands also drive complexity from another angle, explained Samuel Peterson, Business Development manager for the Swedish Space Corporation, which provides launch, mission control, and ground network services to the satellite industry.
“In Earth Observation 10 years ago, we were talking about bringing down gigabits [of data] in a day, now we're talking about petabits. That's two orders of magnitude more data that needs to be delivered,” Peterson said. Once brought to Earth by the downlink, that data still needed to be piped into the terrestrial network, which could be challenging in itself, given the geographical isolation of some ground station locations.
“We have ground stations within the Arctic Circle. We have ground stations that are in the desert, in the middle of nowhere, and getting this amount of data back to civilization from these very remote sites can be a challenge in itself,” Peterson observed.
More satellites in orbit also mean more potential interference from other operators’ satellites, and more radio frequency interference, he added. “We have to coordinate with other operators a lot more to mitigate and make sure that the spectrum can be used efficiently by everybody.” VS