Sky-Fi: How Satellite Internet Links the Globe

Image Source: Ameer/Stock.adobe.com; generated with AI

By Alistair Winning for Mouser Electronics

Published December 19, 2024

Since the Sputnik 1 satellite was launched into orbit on October 4, 1957, to send its distinctive beeping signal back to Earth, satellites have been an essential part of our communication mix.^[1] Naturally, as the internet has become a more important method of communication, satellites have been adapted to fulfill that role, too. Today, a new breed of satellites has the potential to provide internet service to everyone on the planet at a surprisingly low cost.

Although satellite communications have been around for decades, they have usually proven to be expensive in terms of internet accessibility (Figure 1). Terrestrial communications have almost always been the favored method of providing internet access, apart from in a few edge cases, such as in inaccessible areas where installing infrastructure would be uneconomical due to sparse population or challenging terrain. Private sector companies could likely never recoup the capital outlay required to lay cables or install wireless towers that would reach most of the population in these areas. That lack of internet availability almost guarantees that remote communities are left trailing behind.

Figure 1: Satellite communications may be the only economical way to provide essential services in remote communities. (Source: irissca/stock.adobe.com; generated with AI)

In the modern world, we hardly think about how much convenience the internet has brought us. Today, it is likely that most people can’t remember a world without the internet. Areas without internet access are at a distinct disadvantage compared to the rest of society. To connect these areas virtually to the rest of the world, satellite internet would be the only viable option if it were inexpensive enough.

Satellite internet has also proven to be a vital tool for emergency services during disasters. After such events, the power supply to the area is often badly damaged, cutting off communications. Battery-powered satellite equipment allows rescue services and utility companies to coordinate to tackle the problem, restore power, and save lives.

Internet from Space

The first communication satellite was Telstar 1, launched by AT&T in 1962.^[2] Telstar’s elliptical orbit ranged from 592 miles from Earth at its nearest point to 3,687 miles at its furthest point. It could receive and send television broadcasts, telephone calls, and images, but for only thirty minutes in its roughly two-and-a-half-hour orbit.

Later, communication satellites improved on that uptime by adopting a geostationary (GEO) orbit at 22,236 miles above the equator. At that height, the speed of a satellite’s orbit matches that of the Earth, so it stays in the same location relative to the planet and is always in place to transmit and receive data. Three of these GEO satellites can provide coverage to almost the entire globe.^[3]

While GEO satellites have dramatically improved our communications capabilities, several issues remain, including cost. Orbiting at that height above the Earth means the satellites are exposed to heavy radiation from the Van Allen belts, requiring electrical components to be shielded. This, in turn, makes the satellites heavier and further increases their cost.

Earth has two Van Allen belts, whose distance from the Earth can vary between approximately 400 and 36,040 miles.^[4] The donut-shaped belts are thickest over the equator and thinnest at the poles. They are caused by the Earth’s magnetosphere trapping high-energy radiation particles. These particles shield the Earth from solar storms and the solar wind (Figure 2), which can damage electronic systems and harm humans. Because GEO satellites orbit at an altitude of 22,236 miles, they are constantly within the Van Allen belts’ radiation but outside most of the belts’ protection zone against deep-space radiation events.

Figure 2: The Van Allen belts protect the Earth from the worst effects of solar storms. (Source: Naeblys/stock.adobe.com)

That is not the only problem with GEO satellites. That extreme orbiting distance also introduces latency, with the 44,472-mile round trip taking signals around 500ms. Finally, in the event of failure, the whole satellite must be replaced. Redundant systems can help provide a longer operating lifetime for critical systems but add more weight and expense. With all that shielding and redundancy, GEO satellites can cost up to $400 million, weigh up to five tons, and take up to five years to design and build.^[5]

An Alternative Solution

More recently, a new technique has emerged intended to negate the drawbacks of GEO satellites. Instead of relying on a single satellite with multiple failure points and an eye-watering cost, multiple low Earth orbit (LEO) satellites with orbits from 100 to 1,200 miles could act as a single entity to provide coverage of the entire planet. Although a single LEO satellite can cover only a small portion of the planet’s surface and does not remain stationary over the Earth, it does operate under the protection of the Van Allen belts, meaning it does not need the same degree of shielding as GEO satellites.

LEO satellites (Figure 3) are also much less expensive—at an average cost of around $500,000—lighter (between 220 and 2,200 lb.), and can be designed and built in around 18 months. Their launches are more cost-effective and the satellites provide better service with higher bandwidths.^[6] With a typical latency of around 40ms, LEO satellite internet is much closer to the end-user experience of terrestrial communications. If one satellite fails, then the others in the constellation can be rearranged to close any gaps in coverage. Additionally, satellites can be added to the constellation quickly to enhance capacity and provide better service quality.

Figure 3: LEO satellites may not have the view of Earth that GEO satellites do, but acting in a constellation provides better coverage with lower latency. (Source: Photocreo Bednarek/stock.adobe.com)

It is hard to accurately estimate the current number of LEO satellites in orbit, and by the time this article is published, that number is guaranteed to be outdated. Currently, the largest grouping is the Starlink constellation, with around 7,000 total satellites^[7] and as many as 42,000 planned for the future.^[8] This is in comparison to the 600 GEO satellites currently active. Starlink is only one example. China’s Thousand Sails constellation should have 1,296 satellites in orbit by 2027, leading to a final number of 12,000 satellites in the long term.^[9] Amazon is also entering the field with the company’s Project Kuiper, which has a planned constellation of 3,232 satellites and upcoming launches.^[10]

Many technological advancements have enabled so many complex systems to work in tandem. Because satellites are not completely stationary above the Earth, they must cooperate closely with other satellites as they pass over the horizon and lose signal. To communicate with other satellites, newer Starlink satellites feature three lasers that can communicate at up to 200Gbps for inter-satellite communication. Those laser-based communications reduce the workload of the ground station.

Regenerative communication is another innovation that is expected to reduce the number and complexity of ground stations. Early LEO satellites acted as a conduit between the base station and the target location, amplifying only the signal and changing the frequency for broadcast. That technique is known as a bent pipe. Regenerative technology allows satellites to demodulate, decode, re-encode, and modulate the signal to improve the signal-to-noise ratio. It can also selectively process the data if required.

LEO satellites are also starting to integrate 5G mobile communications. 5G non-terrestrial networks (5G-NTN) could be either bent-pipe or regenerative, with the regenerative networks including part or all of the satellite base stations.^[11] This integration could bring many benefits, especially to underserved communities. It would allow populations in remote areas access to mobile communications, Internet of Things (IoT) sensors, and machine-to-machine (M2M) connections, potentially boosting their economies. 5G-NTN can also improve the quality of high-capacity applications. In the case of disasters, LEO constellations could temporarily take over from damaged terrestrial networks.

Electronically steered antennas (Figure 4), such as active electronically scanned array (AESA) and phased-array antennas, are also quickly being introduced to satellites as parabolic antennas struggle to meet rising demands. These antennas can quickly change signal direction electronically, while parabolic antennas need physical movement. These techniques are more responsive and allow beamforming for faster and more accurate adjustments, enabling quicker hand-offs between satellites.

Figure 4: LEO satellite communications only require a small antenna for the end user. (Source: rh2010/stock.adobe.com)

Finally, recent innovations in GEO satellites could allow them to work closely with LEO satellites to provide higher-quality services. LEO satellites could provide fast, low-latency internet globally, while GEO satellites use their high-capacity capabilities to service high-population urban areas for non-time-sensitive applications.

All these techniques allow the satellites to intelligently route and offload traffic, saving valuable spectrum space and improving the network’s resilience.

Conclusion

Technological advancements providing higher throughput and lower launch costs have allowed many different providers to launch constellations into orbit, enormously increasing capacity and decreasing costs for end users. Those lower costs make satellite communications much more economical for remote areas.

While LEO satellite constellations hold great promise for connecting remote communities and driving economic and social benefits, they also present challenges. As we move forward, balancing the benefits of widespread satellite access with responsible management of our orbital space will be essential to sustaining this progress and avoiding congestion in our skies.

Sources

[1]https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1957-001B
[2]https://airandspace.si.edu/collection-objects/communications-satellite-telstar/nasm_A20070113000
[3]https://www.esa.int/Enabling_Support/Space_Transportation/Types_of_orbits
[4]https://spacenews.com/van-allen-probes-spot-an-impenetrable-barrier-in-space/
[5]https://www.te.com/en/industries/aerospace/insights/cots-components-in-leo-satellites.html
[6]https://www.te.com/en/industries/aerospace/insights/cots-components-in-leo-satellites.html
[7]https://satellitemap.space/
[8]https://www.the-independent.com/tech/elon-musk-satellites-starlink-spacex-b2606262.html
[9]https://phys.org/news/2024-10-china-thousand-starlink-latest-mega.html
[10]https://www.aboutamazon.com/news/innovation-at-amazon/what-is-amazon-project-kuiper
[11]https://www.qorvo.com/design-hub/blog/advancing-communication-the-role-of-leo-satellites-in-the-wireless-expansion