The IT Nerd

By Mike Hicks for Cisco ThousandEyes 

Summary

Explore the different types of satellite technology, their strengths and weaknesses, and the factors that must be considered when it comes to digital resilience.

We talk a lot about cloud computing, but there’s a connectivity layer way above the clouds that should be part of the conversation on achieving digital resilience: satellite connectivity.

Both Geostationary (GEO) and Low Earth Orbit (LEO) satellites can be used to deliver high-speed connectivity to remote areas that are underserved by fixed-line networks. But it’s not only people in rural areas who can benefit from satellite connections—they can also provide a very useful alternate option for customers of fixed-line services.

Whether as your primary connection or a backup circuit, there’s a lot to consider when it comes to satellite connectivity, so here we’re going to explore the different types of satellite technology, their strengths and weaknesses in different use cases, and the factors that must be considered when it comes to achieving digital resilience.

Geostationary Satellites

Let’s start with Geostationary satellites.

Geostationary (GEO) satellites orbit at the same rotational speed as Earth. This means that a GEO satellite completes a circular orbit around the Earth in 24 hours. As a result, the satellite’s position and coverage area remains fixed relative to a specific location or observer on the Earth’s surface. They do move occasionally, either because they’ve drifted slightly out of position and need to be moved back, or because they’re being shifted to a new location. The satellites have fuel on board to drive them when needs be, but by and large they cover a specific footprint.

Geostationary satellites orbit at a huge distance from the Earth, approximately 22,000 miles (or 35,000 km) above the equator. That has both advantages and downsides. On the plus side, hovering at such height means each satellite can cover an enormous area on the ground; a single satellite can cover as much as a third of the Earth’s surface.

However, that level of altitude comes at the expense of responsiveness. Latency times can stretch from several hundred milliseconds to 1 second. That’s not a disaster for day-to-day web surfing, but it’s a huge problem for real-time applications such as video conferencing. The bandwidth of geostationary services, particularly on the uplink, is often also restricted to the tens of megabits per second, well below the gigabits per second you can achieve on fiber connections.

LEO Satellites

Geostationary satellites have in many ways been superseded by Low Earth Orbit (LEO) satellites, of which a well-known example is Starlink.

LEO satellites orbit at a much lower altitude, typically in the range of 310-745 miles (or 500-1,200 km). That means latency is greatly reduced, sometimes as low as 50 ms. That’s not quite fiber levels of latency, but it’s not a million miles off either. Bandwidth is considerably greater with LEO than geostationary too, with download speeds stretching into the hundreds of megabits per second.

In contrast to Geostationary satellites, LEO satellites are always in motion. If you visit this map, you can see a mesmerizing real-time map of this enormous mesh of 6,000+ satellites traveling around the Earth.

However, this constant motion can create connectivity challenges. Just like your cell phone connects to different cell towers as you drive down a highway, a satellite receiver must also switch from one orbiting satellite to another as they pass over your location on Earth. We can see from ThousandEyes data—and even in the Starlink app—that at times, this can lead to brief disconnections, causing the receiver to momentarily lose connection with a passing satellite overhead.

How Are GEO and LEO Similar?

Whether GEO or LEO, there are connectivity characteristics with satellite services beyond those we’ve already discussed that are shared by both technologies.

For example, both are currently reliant on ground stations, which send and receive signals from the satellites and connect them to the wider Internet. The satellites then relay this signal from the ground station to receivers in people’s homes or businesses, providing a two-way link.

The availability of ground stations is, therefore, a crucial component in service performance. The closer a user is to a ground station, the faster their data will reach the Internet backbone, because it has less distance to travel. For those living in remote areas, far away from the closest ground station, this can greatly increase latency or decrease bandwidth.

Additionally, both GEO and LEO satellites are susceptible to atmospheric conditions and weather. Factors like fog, heavy clouds, and lightning can disrupt the signal, and even snow accumulation on receiver equipment can negatively affect performance. For instance, to mitigate possible weather impacts, Starlink’s receiver, commonly known as “Dishy,” is equipped with heating elements to melt snow. A clear line of sight from the dish to the satellite is also essential; obstructions such as tree branches swaying in the wind can cause signal disruptions.

Building Digital Resilience

While satellite connectivity has some disadvantages when compared to fixed-line fiber, it also possesses unique strengths. This is why it is increasingly becoming a key component of business resilience planning.

There is not enough satellite bandwidth for communication provider networks to fully rely on satellite as a complete fallback option to serve their customers, but individual businesses and consumers can. In Perth, Australia, I use a fixed-line Internet connection complemented by Starlink. I have router equipment that combines the bandwidth from both connections, allowing me to match network characteristics to application requirements.

This exemplifies an important factor to consider when choosing among various types of Internet connectivity: understanding the characteristics of your applications and aligning them with the network’s capabilities. For instance, the Starlink connection offers significantly higher downstream bandwidth compared to my fixed-line connection, making it more suitable for activities like streaming video or general web browsing. In these scenarios, latency or occasional connection drops are not critical issues as most streaming services buffer a few minutes of video in advance to accommodate potential network interruptions.

When it comes to video conferencing or recording The Internet Report podcast, however, I usually opt for a fixed-line connection. For real-time applications like these, where I’m engaging in conversations with people around the world, it’s essential to minimize latency and ensure consistent service. Inconsistent lag or signal drops can lead to a degraded experience (not to mention an awkward conversation!). Therefore, I prioritize reducing latency and improving consistency, even if it means sacrificing some bandwidth, by using the network that best fits the requirements of these applications.

This comes back to a favorite theme of mine: having a holistic understanding of your overall service delivery chain. Resilience is about keeping the lights on, making sure you always have sufficient connectivity to meet your demands. Whether you opt for fixed-line as your primary connection and satellite as your fallback, or vice versa, will depend on your individual requirements.

One important requirement to consider is the need for reliable connectivity while on the move. Initially, Starlink focused on providing satellite connectivity to specific fixed locations. However, it now offers Starlink Mini, which allows you to take a portable unit with you when you travel. Additionally, special equipment is available for use on boats, where other coverage options might be limited. As a result, given these on-the-move use cases, satellite connectivity may be used in conjunction with 4G or 5G services, instead of relying solely on fixed-line connections. This creates an entirely different set of characteristics to compare.

Improving Traffic Flow

Although satellite connectivity presents challenges, particularly the risk of service interruptions, various traffic management measures are being developed to mitigate these risks and enhance resilience.

One such measure is the TCP BBR (Bottleneck Bandwidth and Round-trip propagation time) congestion control algorithm created by Google, which is utilized for services like YouTube and Google Cloud. Unlike traditional algorithms such as CUBIC, which rely on packet loss to detect congestion, BBR assesses the available bandwidth between the sender and receiver and optimizes the data transmission rate accordingly. It continuously monitors the round-trip time and adjusts the data rates to adapt to changing network conditions.

This approach is especially beneficial for high-latency connections like satellite Internet, as BBR aims to maximize throughput without significantly reducing transmission speeds when packet loss occurs, as older algorithms tended to do.

Google asserts that BBR helps maintain shorter network queues, which can reduce round-trip time by a third. This improvement positively affects response times in latency-sensitive applications, such as chat and gaming, which, as mentioned earlier, are not ideally suited for satellite links.

Space-age Resilience

It’s astounding that satellites traveling at 17,000 mph can enhance the reliability of your Internet connection, but it’s true.

Whether it’s as a backup link to a fixed-line connection or even as your primary connection in an area with limited access to fiber, satellite connectivity is now an affordable, high-speed alternative. Your individual needs and application characteristics must be considered carefully, but space really could provide that extra layer of connectivity resilience you’ve been looking for.