From PlextekReviewed by Olivia FrostApr 7 2025
As 5G and 6G technologies evolve, their integration with satellite networks is transforming global connectivity. In this interview, Kevin Cobley and Richard Jacklin from Plextek discuss the rise of Non-Terrestrial Networks (NTN), the shift toward Direct-to-Device (D2D) communication, and the challenges of scaling satellite-based mobile networks.
With major players like Apple, Starlink, and Iridium entering the space, they explore the competitive landscape, the need for efficient frequency use, and how Plextek drives innovation in power management, radio design, and scalable satellite communications.
Can you briefly overview how 5G/6G technologies intersect with space and satellite communications?
Kevin Cobley (KC): We are all somewhat familiar with 5G from our mobile phones. Typically, our mobile phones are served by a base station on a tower physically connected to the ground. These towers need to be quite tall to improve coverage and connectivity. Looking ahead, there is a growing interest in the space industry in positioning base stations in the sky.
This approach helps achieve two key objectives. The first is providing industrial IoT connectivity to remote locations, such as oil pipelines or other infrastructure requiring low-data-rate communications, but in areas where it is tough to access power, let alone install a mobile base station.
The second objective is to reduce the investment needed to extend mobile technology to regions where it is commercially challenging to justify building a terrestrial base station network.
Non-terrestrial networks are specifically designed to address these challenges. While some of these issues may be mitigated by other solutions, space-based infrastructure, such as low-Earth orbit satellites, offers a unique and effective alternative in many cases.
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Richard Jacklin (RJ): The intersection between 5G and 6G technologies and space and satellite communications has existed since the early days of cellular networks.
The demand for mobile coverage and data services continued to grow, backhauling became increasingly important for connecting base stations to the core network. This process involves transporting traffic from the base stations to the mobile switching center via satellite links, microwave radio links, or other means of communication.
As far back as the 1990s and early 2000s, during the era of 2G and GSM cellular communications, satellite networks were commonly used for backhauling in remote and hard-to-reach areas, such as rural and agricultural regions.
This relationship between satellite networks and mobile network operators has continued through the evolution of 3G and 4G and is expected to remain relevant in the future.
The key difference between 5G and 6G is the shift in how satellites are utilized. Previously, satellites primarily served as backhaul, providing core network connectivity to remote base stations. However, with 5G and 6G, satellites are now being considered for direct connectivity between base stations and user devices. Instead of being on the ground, base stations are being integrated.
This shift leads to the concept of D2D, where the satellite itself acts as the base station rather than simply serving as a relay for backhaul. The goal remains consistent: to achieve seamless global communication, ensuring connectivity everywhere and at all times, regardless of location.
How would you explain Direct-to-Device (D2D) communication and Non-Terrestrial Networks (NTN) to someone unfamiliar with these concepts? Why are they so critical for the future of connectivity?
RJ: NTN is a broad term that refers to base stations and network infrastructure that are not on the ground. This could include satellites, airborne base stations installed in aircraft, or high-altitude platforms, which involve long-term gliders operating in the stratosphere for weeks at a time. At even higher altitudes, NTN encompasses satellite-based communications. The term NTN covers all these technologies as a group.
KC: Current satellite coverage for mobile devices usually requires bulky antennas or offers very low data rates. These systems are often indirect, routing traffic to space and then back to a base station on the ground. D2D is a better alternative, where the actual base stations are part of the NTN, giving users direct access to the network with lower latency and greater throughput.
D2D offers many benefits, although it comes with size, weight, and power challenges. The cost of deploying and maintaining NTNs is closely tied to these factors, which is why so many technical hurdles must be overcome to make it viable.
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The current NTN landscape has been described as a "multi-dimensional Rubik's cube". Can you elaborate on what makes this field so complex?
RJ: One of the interesting aspects of non-terrestrial networks and direct-to-device communications is that, at this point in time, there is no clear leader in the race. There are multiple approaches, each of which can be segmented in different ways, which is where the comparison to a Rubik’s Cube comes in.
One factor is frequency allocation. There are different approaches regarding how frequencies are used.
Another factor is how much of the radio infrastructure should be placed in space. When setting up base station infrastructure, the simplest method is known as "bent pipe" communications, where data is relayed from the ground to a base station in the sky and then sent back to the user’s device.
While straightforward, this approach has drawbacks, including longer latency, which negatively impacts the user experience. A more effective method is to incorporate additional processing power into the satellites themselves, a concept known as edge processing.
This improves the user experience by reducing latency and preventing network congestion, particularly for activities such as streaming videos. However, placing processing capabilities in satellites increases power consumption, which is a critical issue, as power is highly limited in orbit.
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Given the increasing involvement of big players like Apple/Globalstar, Starlink, Iridium, and AST Mobile, how is the competitive landscape shaping up?
RJ: The key players are carving out different positions. Apple and Globalstar have chosen to adopt the satellite spectrum for device communication, which works well for Apple due to its significant market share.
This allows Apple to scale and secure the necessary semiconductors for those frequencies. However, this approach results in a proprietary system that is incompatible with Android or other phone manufacturers, creating a closed ecosystem.
Iridium and similar companies have been established in this industry for a long time. They primarily serve government, maritime, and emergency-use cases rather than the general consumer market. Each of these players is targeting a specific
One of the significant challenges in space and satellite communication is efficient frequency usage. What are some key issues, and how does Plextek approach solving them?
KC: High spectral efficiency is one of 5G's defining features. Leveraging these technologies can lead to more efficient use of the frequency spectrum. However, doing so requires overcoming serious technical constraints in space-based systems and user devices.
Large antennas may not be practical in many environments. That's why we specialize in developing lightweight, compact, and highly efficient solutions that meet these constraints without sacrificing performance.
Another critical factor is the integration of antennas and radios, especially when using massive MIMO (multiple-input, multiple-output) technology. MIMO systems need many antenna elements, which means segmenting the hardware to drive each one. This drives us toward fully integrated units where the antenna and radio head are combined, making the antenna a fundamental part of the electronics.
To do this well, you need expertise in antennas and radio systems. Plextek's system-level approach ensures these components work seamlessly together.
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Another major hurdle is the power budget for handset-to-space communications, especially considering the constraints of both devices and flying base stations. What innovations or solutions is Plextek exploring in this area?
KC: In all mobile 5G and 6G applications, there is a critical need for both linearity and power efficiency, and these two factors are closely linked. Achieving good linearity enables better power efficiency, which has long been a key technological differentiator in mobile communications, particularly for base stations.
Plextek is actively developing AI and machine learning to improve the performance of base station hardware, especially in terms of linearity and power consumption.
RJ: The distance between a mobile device and a satellite is significantly greater than between a terrestrial base station and a mobile device (300 to 500 kilometers versus 15 kilometers). That alone creates a major power challenge.
Satellites often spend extended periods in eclipse, during which they cannot generate power because they are on the dark side of the Earth. This limitation necessitates careful power management strategies.
Integrating these constraints into a cellular network requires innovative solutions to ensure reliable transmission over long distances. In contrast, terrestrial networks benefit from continuous access to grid power, eliminating concerns related to power shortages or eclipse periods. This fundamental difference underscores the complexity of power management in satellite communications.
Higher latency is often associated with satellite networks, particularly in data performance. How does Plextek propose to address or mitigate these issues to ensure a seamless user experience?
RJ: Latency is related to the distance of these satellites. The laws of physics cannot be broken. If a base station is 300 to 500 kilometers away in space, it will experience greater latency compared to a terrestrial network, and nothing can be done to change that unless a way to exceed the speed of light is discovered.
So, instead of eliminating latency, we focus on minimizing its impact. One way is to perform edge processing in space instead of relying on the bent pipe (relay) method that sends data back to Earth for processing. Edge processing allows quicker responses and smoother user experiences, but it's power-intensive. This approach provides the best user experience but is power-intensive.
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What are some of the broader technical contributions that Plextek can bring to the evolution of NTN and D2D communications?
KC: One key area is network design, particularly using AI-driven prediction tools for propagation modeling in rapidly deployed networks. A good example of this is in disaster zones, where traditional infrastructure may be destroyed.
In such situations, it is critical to deploy a non-terrestrial network quickly to determine exactly where communication is possible. We have developed AI-based prediction tools to help with this.
RJ: Signal loss over space is a huge problem. Transmitting over hundreds of kilometers means much higher free-space path loss than in terrestrial networks. So, every fraction of a decibel matters.
We focus on minimizing losses. Whether through better filters, low-noise amplifiers, or reducing system noise. Kevin is an expert in this area, and optimizing front-end performance is one of our most impactful contributions.
Another big piece is scalability. Satellite companies are used to building thousands of units. The mobile industry? Billions. We help bridge that gap by designing products that are scalable, cost-effective, and manufacturable in high volume, without exotic materials or hard-to-source components.
How do you see the convergence of 5G/6G technologies and NTN impacting industries like defense, industrial IoT, or consumer communications? Are there specific opportunities you find particularly exciting?
KC: IoT solutions have long struggled with reliable data backhaul from the site to central computing. NTNs have the potential to solve this issue, but developing low-power solutions for these networks will require careful optimization—an area we are particularly interested in.
One of the key attributes of 5G and 6G is their configurability. These technologies allow for rapid network deployment and dynamic adaptation. With NTNs, it becomes possible to establish a network in difficult circumstances with minimal infrastructure, reducing network downtime and dependency on vulnerable infrastructure.
RJ: One of my interests is cruise ship connectivity. I like photographing antennas and running Wi-Fi tests when I travel. I post about it on LinkedIn, and funnily enough, it gets the most engagement because people relate to the pain of expensive, flaky internet at sea.
Traditionally, cruise ships have been a major revenue source for satellite providers like Intelsat, SES, and Telesat. However, the introduction of Starlink is already reshaping this landscape. Looking ahead, as D2D satellite connectivity becomes widely available, the business model will evolve once again.
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What message would you like to convey to potential partners or stakeholders about your vision and expertise in this domain and beyond?
RJ: Plextek stands out in the industry by maintaining independence from specific vendors, enabling the company to support a broad range of partners. Its core strength lies in technical expertise, particularly in RF front-end design, low-loss and low-power solutions, and key design-for-excellence principles such as scalability, manufacturability, and testability.
Plextek’s testing capabilities are bolstered by anechoic chambers and open-area test sites, ensuring precise and reliable performance assessments. Additionally, the company has developed expertise across both ends of the communication link, from device-side development to payload electronics for space applications.
Operating in space presents unique challenges, including extreme temperatures, radiation exposure, power constraints, atomic oxygen, and the intense shock and vibration of launch. With a strong track record in addressing these challenges, Plextek has positioned itself as a trusted partner for mission-critical space technologies.
About Kevin Cobley
Kevin Cobley, Director of RF systems engineering at Plextek, is a communications expert with over 25 years of experience in RF systems design. His specializations include leading multi-disciplinary teams, driving technical excellence, and bringing innovation to positively impact the mobile communications industry, including handset and infrastructure designs for both the terrestrial and the satellites and space sectors.
About Richard Jacklin
Richard is the Commercial Lead for Plextek Services, helping customers design and produce highly innovative radar and radio communications-enabled solutions, specializing in the space and satellite market. In his career, now over 30 years, he has regularly presented and contributed to many international forums, including CONFERS, Satcom Innovations Group, Cambridge Wireless, and GSMA working groups. Richard graduated from the University of Portsmouth with a degree in Electronic Engineering, and he was also awarded Chartered Engineer status and Fellow of the Institute of Engineering and Technology (IET).
About Plextek
With over 35 years of experience designing and constructing low-SWaP (size, weight, and power) radio and radar-based systems, Plextek is committed to the space sector, providing innovative space-qualified sensing technology solutions. Utilizing cost-effective, integrated commercial-off-the-shelf radar components, Plextek has successfully tailored these technologies to meet the specific requirements of the space environment.
This information has been sourced, reviewed, and adapted from materials provided by Plextek.
For more information on this source, please visit Plextek.
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