LEO and the ground segment
Is there enough consideration being placed on the ground segment, or is there a risk that an inadequate ground segment could end up stifling the LEO juggernaut?
Helen Weeden, Managing Director, the Satcoms Innovation Group
There is no arguing it, satcom is expanding. As the number of satellites in-orbit rockets, particularly in LEO, the impact is not only being felt in the space segment, but also at ground level. The call for sustainability and coordination within orbit is frequently discussed, however the ground segment can often be seen as the less exciting side of the landscape, sometimes garnering less attention. Yet when considering the safeguarding of satcom, sustainability of the spectrum is as fundamental as managing space debris because an ill-performing ground segment can have huge ramifications on the reliability and profitability of satcom.
It’s well known that LEO ground segments are hugely complex on several fronts. Not only are there more users tapping into RF waves than ever before, but the phased array antennas required for LEO are also technologically complex because they need to track and handover satellites. This creates a number of challenges that need to be addressed.
RESPONSIBLE SPECTRUM USE
According to Mark Steel, Director, Satcoms Innovation Group, “As LEO satellite constellations have expanded, the demand for spectrum has incrementally increased, which brings concern about spectrum congestion and interference.
“To sustain operation and prevent interference, it is critical that we adhere to regulatory requirements, as well as ensuring the regulatory domain is aligned to the product innovation and implement testing standards that prove the terminals’ compliance. With these rapid deployments, traffic management and space debris mitigation drive the need for collaboration and compliance at multiple levels of our industry to prevent significant implications.”
This view is shared by Joakim Espeland, CEO, Quadsat, who adds, “While there is regulation around spectrum, it hasn’t fully kept up with the fast evolution in the satcom environment. The same standards and best practices for a GEO environment, for example, are not always relatable for LEO or multi-orbit environments. As technology continues to evolve fast, we need to take the time to revisit what responsible spectrum use looks like.”
The lack of consideration around responsible spectrum use is also causing coordination issues, as mentioned by Emmanuel Houdet, Director, Kratos. He notes, “Spectrum
use is such a critical issue. It is important to increase awareness and ensure its most efficient usage. While monitoring satcom NGSO constellations for operators and for frequency regulators, there have been many cases of frequency coordination issues. This is true between constellations as well as between constellations and geostationary satellites.”
Alvaro Sanchez, CEO, Integrasys, agrees. “Spectrum is a strategic asset to enable communications so we must use and renew operating licences,” he notes. “The Western World tends to be more responsible about spectrum use than the East especially in times of conflict. Take for example, all that’s happened in Ukraine, Iran, and other jammed and spoofed regions, or in space operations. However, there are still some Western LEO companies that are transmitting above the limits”.
THE BIGGEST CHALLENGES
IN LEO GROUND SEGMENT OPERATIONS
LEO ground segment operations are clearly hugely complex and as such, face a unique set of challenges.
As Steel explains, “LEO satellites move rapidly across the sky so ground stations need advanced tracking capabilities to maintain communication, which increases interference risks. Ground segments must also maintain and improve reliability/performance, but we must not fall into the trap of driving cost down and impacting overall quality. The regulatory and testing of these systems will need to adapt to handle these challenges effectively.”
“The complexity of orchestrating such a dynamic ground and space network with few gateways that serve many satellites with limited visibility of users represents a challenge in most cases,” adds Sanchez. He believes that smarter tools which combine capabilities from Space Domain Awareness, Orchestration and Sensing the RF spectrum are key to addressing the challenges in the LEO ground segment and managing networks across LEO, MEO, HEO and GEO.
Espeland agrees that the complexity of LEO ground segment antennas is a significant challenge. “These antennas need to be capable of tracking satellite passes,” he says. “Once you add in the need to switch to different
Helen Weeden, Managing Director, the Satcoms Innovation Group
satellites, you are increasing the room for error, which can cause an increase in interference. It is therefore important to test the ability of that ground equipment to operate in those real-life scenarios.”
Limited spectrum visibility is another major issue, as Houdet explains, “Monitoring at the gateways is not sufficient as it only provides a partial and local view of the spectrum. NGSO satellites are using spot beams, and the operators are only monitoring the gateways. This does not show what is happening on the user terminal beams. Ideally, one monitoring system per user beam is needed; however, that can be a challenge for technical and economic reasons, so the monitoring needs to be prioritized according to the value. The operator can rely on feedback provided by terminals to help as well, but there is still the challenge of determining the actual root cause when an issue is detected.”
Kevin Dunne, CEO, ETL Systems, adds: “For commercial operators, cost is a critical factor, particularly at the scale of mega-constellations like Starlink or Project Kuiper. Building and maintaining the necessary infrastructure, including numerous ground stations and network equipment, is expensive. Making these organizations commercially viable involves delivering innovative service models to leverage new markets and offset the investment required. This is further complicated by the lack of standardization in satellite ground segments which increases the risk of vendor lock-in and driving up costs for implementation of a wide scale.”
MITIGATING INTERFERENCE BETWEEN LEO SATELLITES
Recent statistics suggest that Radio Frequency Interference (RFI) is increasing. This could be partly due to
the geopolitical situation, as well as the fact that the number of objects in space has increased dramatically. As an industry, we need to act now to ensure we can reduce the occurrences of RFI and resolve it quickly when it does occur.
Mitigating interference in any orbit requires the right tools as well as collaboration between operators. However, as Espeland explains, “It is particularly challenging for LEO because of the sheer volume of satellites we expect to be in orbit in just a few years, as well as the more complex nature of LEO and the subsequent demands on the ground segment.”
“We need to adopt innovative strategies and enhance existing practices which will require collaboration among satellite operators, regulatory bodies, and manufacturers,” adds Steel.
Like Steel, Sanchez believes that collaboration between industry and regulators is key. “We at Integrasys are supporting regulators on how to coordinate and on what regulatory measures we should take into account for WRC27 for LEO to LEO interferences.” He says, “Space has become much more dynamic and only being able to advance [regulations] every four years (WRC to WRC) becomes a challenge so we must help regulators to predict the future for the next four years.”
Houdet on the other hand, thinks that monitoring the NGSO constellation’s RF spectrum is key to mitigating interference and assuring the spectrum. RF monitoring allows satellite operators, service providers and regulators to detect issues, evaluate the impacts on services, understand the causes and work together to resolve any issues. He notes, “All commercial space actors as well as country frequency regulators should start monitoring
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NGSO constellations RF downlinks to detect issues, evaluate the impacts on other services, and understand the causes.”
ENTER FLAT PANEL ANTENNAS
Flat Panel Antennas (FPAs) are clearly instrumental for the next iteration of satcom. As Sanchez puts it, “They are crucial for LEO success and the time is now.” Yet their use also comes with challenges. Sanchez believes that digital twin tools will play an important role in helping operators to address some of the challenges associated with FPAs because such tools allow operators to input the measured antenna pattern to certify their performance and isolation.
Dunne adds, “One of the keys to overcoming the current challenges of scale and performance faced by LEO-centric organizations is the integration of FPAs… although this adds complexity to network management systems.”
This is a view shared by Steel. “FPAs will be crucial for the future of LEO satellite systems for many reasons like their compact design, high performance, ability to support multi-orbit and multi-band networks, and ability to connect to multiple satellites simultaneously.” He says. “The ability to enable seamless tracking and handover between satellites is essential for maintaining continuous service in the LEO constellations. However, there are challenges associated with using FPAs, which to address will require industry-wide collaboration, innovation, and the establishment of clear performance and testing standards across the globe.”
Espeland agrees that FPAs are crucial for LEO. “It simply isn’t viable without them. However, many challenges remain when it comes to their operation and to ensure consistent quality.,” he explains. “We need to work together to agree on standardized testing procedures and data set requirements”.
Espeland believes that this will make it possible for manufacturers to quickly and easily provide the right information to satellite operators, so they can make informed decisions about when and where to allow FPAs on their networks.
“FPAs are the best solution to bring the level of performance, flexibility and speed that is needed”, adds Houdet. “Only FPAs can switch from one satellite to another within milliseconds to ensure service continuity.” However, he also points out that challenges arise because the
proliferation of FPAs will increase the generated level of noise and FPAs are also known to have bigger and stronger side lobes compared to parabolic antennas. These factors are problematic because they are likely to increase risk of interference.
FUTURE-PROOFING GROUND INFRASTRUCTURE AND SUPPORTING FURTHER EXPANSION OF LEO
According to Dunne, “The development of multi-X equipment, supporting multi-orbit, multi-band, and multiwaveform operations, is also essential for LEO to serve diverse verticals with flexible terminal solutions.” In addition, he sees digitalization as a key requirement: “Digitalization through standards like DIFI is needed to support virtualization, enabling software-based alternatives to hardware components like modems and RF matrices, driving agility and cost-efficiency in the longer term as satcom joins the digital revolution.”
Espeland believes innovation around testing will also be critical, “We have already seen a great deal of innovation across the ground segment with new technology to manage multi-orbit, satellite passes, and even the transition to cloud-based workflows,” he asserts. “This is all extremely vital and needs to continue, but especially with the added complexity this all brings, we also need innovative ways to test that everything is performing as it should be and will perform seamlessly in real-world operational scenarios.”
“Future-proofing ground infrastructure for (LEO) satellite expansion requires a blend of technological advancements and strategic planning with innovations designed to address the current challenges but also prepare the ground segment for the demands of future satellite constellations,” explains Steel.
There is also a need to utilize AI, as Sanchez explains, “We need to enhance [use of] AI in signals as well as selecting the best path and way to serve a particular user terminal, and user need.” He believes that this will be especially important in a contested environment.
While there are some hefty challenges around LEO expansion and its supporting ground segment, they are not insurmountable. With greater collaboration, smarter tools, and continued innovation across technology, regulation, and testing, the ground segment can evolve to not only keep pace with the LEO revolution, but to help drive it forward.
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