In recent months, the expansion of LEO constellations has created a consistent buzz within the satellite industry, as well as capturing the public’s imagination. Large scale deployments of Starlink’s LEO satellites are well underway, promising to deliver internet coverage to remote locations for the first time, as well as significantly improving latency for areas with existing broadband infrastructure.
It is widely acknowledged that a successful LEO constellation will be a game-changer for communications and connectivity, increasing bandwidth far beyond the current GEO and MEO satellite capabilities. However, LEO deployment hasn’t followed a smooth path so far and while SpaceX currently seems the most likely market leader, there is still an element of unpredictability within the sector.
OneWeb’s recent filing for Chapter 11 bankruptcy, with 74 satellites still in orbit, and the earlier failure of LeoSat, are examples of what happens when development and operational costs outpace the ability to secure funding. While One Web’s bankruptcy was heavily affected by the economic impact of COVID-19, it has left potential LEO investors wary, as market disruptions continue in the wake of the pandemic.
Given the current landscape it’s likely that only the most robust and cost-effective solutions will survive, and they need to be developed as quickly as possible. As Elon Musk said recently, “If the schedule is long, the design is wrong.”
While SpaceX has significantly cut costs in one of the most expensive parts of the chain, by launching satellites with its own reusable rockets, it initially struggled to develop a low-cost receiver that was simple enough to be installed by any user. Proving that what happens on the ground can sometimes be the most challenging part of the development process. SpaceX has recently overcome this hurdle, finalising the design and receiving FCC approval for up to 1 million in the USA.
Development Challenges – The Ground Segment
The ground segment is often overlooked in favor of the more glamourous space segment, but it represents a vital link in the chain for the global connectivity that LEO promises. The “UFO on a stick” antenna, as Musk refers to it, may offer a “plug-in and point at the sky” solution that will be mimicked by other operators, but delivering a cost-effective way to manage ground signals is still a crucial part of the LEO infrastructure.
The current focus for LEO operators is to ensure that the satellites operate seamlessly; however, as constellations expand, they will need to bring the focus back down to Earth. While the receivers have been finalized, the ground segment infrastructure hasn’t been fully developed. There is one thing that everyone in the development phase agrees on though – it must be affordable.
A LEO teleport is completely different to a GEO teleport, featuring distinct antenna and switching systems. If cost-effective equipment capable of handling the signals isn’t developed quickly, then the LEO constellation itself is effectively redundant. With regards to technical function, LEO will require significantly more switching, and therefore more gateways and more gateway antennas than ever before.
When it comes to the ground infrastructure for LEO, one thing for certain is that there are four key development areas to consider:
The RF Signal Frequency that will be used
Before you can develop the right ground station equipment, you need to know the signal frequency range that will be used to ensure that the equipment can be fully optimised. This is a simple yet extremely critical element within LEO ground station design, which we cannot afford to overlook.
Which bandwidths the competing constellations will operate on
Frequency will be an issue for LEO as these satellites will operate in Ku- to Ka-band with very Low Earth Orbit (VLEO) satellites operating in V-band, a very high frequency. The size reduction these bands deliver will be extremely important in LEO, as operators are looking to keep equipment to a minimum. That means that any ground station equipment needs to be compact while offering full functionality.
However, what we will likely also see is that the bandwidths will differ globally, with the potential for different bandwidths in each country. Geographically, we are likely to have other potential challenges, as some countries may not allow access to these bandwidths. Once we know who the customers are, ground infrastructure can be installed in the areas where the customer is actually using it, which will help to mitigate this problem. With ground segment installation linked to demand, the industry will need to work closely with both governments and regulatory bodies, in order to achieve cost-effective results in the correct locations.
Redundancy is of course front and centre for every satellite operator, but for LEO operators it is even more so. LEO faces a fairly unique set of challenges within the industry, with satellites travelling at high speeds in low altitudes. This results in LEO smallsats having to be ‘passed’ from ground station to ground station as they orbit, to allow them to relay information seamlessly. A completely different approach to current ground station usage, and it raises a few questions regarding their existing capabilities.
We know that switching between these fast-moving satellites effectively, presents a challenge. Auto switch-over will be absolutely vital to ensuring consistent, uninterrupted connectivity and switches need to be agile enough to manage all frequencies and shift quickly from one satellite to the next.
At the same time, we must consider cost and simplicity, it’s a balancing act that all manufacturers should be working toward.
With many of the LEO satellites operating in Ku- and Ka- band there is a very real risk of rain-fade and other atmospheric conditions. Having backup sites will be extremely important, as will the tools to divert RF signals between sites to ensure services remain connected.
Keeping Costs Low
In order for LEO to compete with existing systems, and each other, development and production costs need to be low. This is apparent from the whole way in which these systems are being built and launched. When it comes to the ground segment, there is a great deal of pressure from the LEO operators to keep those costs low as well, while ensuring good resiliency, continual availability, and small, compact units. That will likely be a challenge for many ground equipment manufacturers.
ETL Systems has for some time been predicting the type of designs that will be required to control, monitor and handle RF signals connecting the ground with the LEO constellation. We have a dedicated team of RF engineers whose primary job is to work on the aforementioned development areas.
Looking to the Future
We are beginning to see more collaboration between the ground segment and space segment in the satellite sector. This represents an exciting new future for the industry. LEO has set the challenge, and now ground segment stakeholders need to rise to the occasion and deliver on a key part of the chain. The recent expansion of video streaming and High Throughput Satellite (HTS) capacity and has put satellite capacity pricing under strain, but as long as the satellite market continues to offer a competitive price per bandwidth it remains valuable. Working collaboratively with LEO operators will help to support this.
LEO constellations will focus on selling megabits rather than megahertz, and in some instances, will reduce uplinks and downlinks through intersatellite links using onboard lasers. As an RF equipment manufacturer, ETL Systems has the capability to manage the bandwidth and multiple links as required. As connectivity increases there will be an explosion in the number of links, which is where ETL System’s equipment and experience will be invaluable. All development teams must position themselves to respond to that need.
The emergence of LEO offers an opportunity for GEO ground system manufacturers to develop new products for a lucrative market, capitalising on years of GEO experience. We haven’t seen significant change within the ground segment of the satellite industry for a long time, and LEO is really driving innovation. It’s a truly exciting time to be working within this sector.
Author Alex Donnison has a dual role at ETL. He works in components sales and is also the Business Development Manager. In his Business Development role, he is involved in the future strategic direction for the company.