Satellite Internet - A Quick Primer and Survey of Solutions to Improve Performance

Getting your internet from an orbiting earth satellite sounds pretty awesome, doesn’t it? Are you ready to switch right now? Hopefully not since satellite internet remains the absolute last option for most consumers, perhaps with the exception of…dial-up internet service. However, if you live in rural areas or locations without DSL/fiber/cable internet providers, then satellite internet may be your only choice.

Of course, Satellite communications (SATCOM) are a mainstay of the US and most foreign governments as satellites, both commercial and government-owned, provide invaluable capabilities. Having a dedicated satellite for SATCOM allows for the most robust and effective security posture, as government agencies can deploy encryption algorithms and secured protocols that greatly enhance their network security relative to the world-wide internet. And the ability to deploy military satellites over war zones or other areas of national security interest is critical to mission success.

In today’s blog, we’ll discuss satellite internet in broad terms and also dig a little deeper into the current state-of-the-art and discuss the inherent challenges that satellite internet poses and how many of these shortcomings can be addressed using satellite bonding with SD-WAN routers. We’ll discuss how current satellite internet providers are providing internet access and talk about future plans – and there are some BIG plans indeed. Let’s get started.

Basic Architecture

Currently, satellite internet is provided to consumers via communication satellites in geostationary earth orbit (GEO). These satellites are all distributed around the equator (0 degrees latitude) at various longitudes and at a distance of 22,236 miles. At this distance the satellite’s time-to-orbit perfectly matches the earth’s rotation rate, and so the satellite remains “fixed” relative to a ground observer as the earth rotates. This means that you can always locate that particular satellite at the same spot, regardless of time of day or time of year. The GEO satellites can potentially illuminate thousands of square miles which means you don’t need very many of them to cover an entire continent.

Some interesting trivia about GEO is that it was first popularized by the prolific science fiction writer Arthur C. Clarke in the 1940s and the first GEO satellite was launched in 1963.

If you want to use SATCOM for your regular internet usage, you need a home satellite dish to communicate with the satellite. These dishes are relatively small, typically 18”-30” in diameter and would be provided and mounted on your roof by the provider, locked in place so it is always pointing at the satellite. You also need some cabling running from your satellite dish to your satellite modem located inside your home or office.

So now you can communicate with the satellite in both downlink and uplink directions. But the lone satellite orbiting the earth doesn’t know anything about the internet and how to identify specific domains and/or IP addresses. To get information about the internet, the satellite needs to communicate with another (much larger) ground-based satellite dish and associated technology, typically referred to as the Network Operations Center, or NOC. The NOC acts as the internet gateway for the satellite so all internet traffic flows between the NOC and the satellite.

Inherent Problems

There are several significant and inherent problems with satellite internet using GEO satellites. They can generally be broken down into 4 areas:

• Latency – This is the time it takes to receive a response on the internet, basically the “ping” time. For DSL/cable/fiber typical latencies are around 20-50 ms, which is generally fast enough so real-time applications perform quite well, without much noticeable lag for the end user. However, for satellite internet, the radio signals need to travel all the way out to the GEO satellite – 4 times for a typical request. Suppose you are simply trying to ping Google. Your ping request travels from your home dish up to the GEO satellite, then back down to the NOC where the request is serviced, then the response from Google travels from the NOC to the GEO satellite, and finally back to your home dish. Even travelling at the speed of light, each leg here will take an absolute minimum of ~120 ms, which means your ping time will be at least ~500 ms. Although half a second doesn’t seem like much, it makes many real-time apps (such as VOIP), VPNs, and interactive gaming virtually unusable. Additionally, the most common transport protocol, TCP/IP, does not perform well with such high latencies unless some smart technologies such as PEP (more on that later) are used.
• Bandwidth – A single satellite has limited maximum throughput or bandwidth. A typical value is about ~260 Gbps and that bandwidth must be divided up among the thousands of customers using the internet simultaneously. By necessity this means the ISP is forced to use bandwidth capping and throttling for individual users. This means you can count on significantly slower internet during peak times.
• Performance – There are two primary factors here negatively affecting performance. The fact that the signals must travel a long distance through the atmosphere and the fact that satellite internet uses high frequency K-bands (12-30 GHz) means that atmospheric conditions and physical obstructions will negatively impact performance. In particular, “rain fading” is a common problem that refers to signal strength fading in and out due to heavy rain or snow. And of course if your neighbor adds a second story to their house that blocks your satellite dish from a direct line-of-sight to the satellite, you are out of business.
• Cost – Satellites are very expensive to build and launch and that cost is passed on to the subscriber base for satellite-based internet. Monthly costs are still typically higher than for DSL/cable/fiber and comes with reduced performance, although the prices are becoming more competitive with each passing year.

Performance Enhancing Proxies (PEPs)

Due to all the inherent performance issues with SATCOM (particularly latency), performance-enhancing proxies (PEPs) have been developed to improve the overall performance. Wikipedia defines PEPs as “network agents designed to improve the end-to-end performance of some communication protocols.”

PEPs can be classified according to three general classes:

• Proxy Type (Spoofing)
  • The PEP can either “split” a connection by pretending to be an endpoint, or “snoop” into it by controlling transmissions in both directions by ack-filtering and reconstruction.
• Distribution
  • The PEP can be either “integrated” which runs on a single box, or “distributed” which runs at each end of the transmission link.
• Symmetry
  • The PEP may or may not be symmetric with respect to each leg of the transmission, for cases where each leg (uplink/downlink) has varying characteristics

A PEP that is commonly used in SATCOM to reduce latency is Split-TCP which works by breaking a single TCP session into multiple sessions and then using custom parameters (such as larger window sizes) to control transmission on each leg. Other PEP types include Ack decimation, Snoop, and D-proxy.

Satellite Bonding using SD-WAN

Performance enhancing proxies are network agents that help with some of the inherent issues, particularly latency, with SATCOM. However, many underlying issues still remain. Another very promising technique for dramatically improving SATCOM involves the SD-WAN technologies that are capable of bonding of the satellite links either with another satellite connection or with other, wired, broadband transports, such as DSL, cable, and/or fiber. SD-WAN solutions with specialized algorithms are required to cope with the higher than normal latencies of SATCOM.

Current Satellite Internet Providers

Currently there are two dominant providers of satellite internet – ViaSat and HughesNet. A recent review comparing the two providers can be found here, on reviews.org.

Below I’ve listed some specs for baseline plans from each provider, just to get a quick comparison:

HughesNet 10 GB Data Plan

• $59.99 per month
• Download speeds up to 25 Mbps
• Upload speeds up to 3 Mbps
• 10 GB data cap per month, after which your bandwidth will be throttled

ViaSat Unlimited Bronze 12 Plan

• $50 per month for first 3 months, then $70 per month
• Download speeds up to 12 Mbps
• Upload speeds up to 3 Mbps
• 35 GB data cap per month, after which your bandwidth will be throttled

What About Low Earth Orbit Satellites?

If using GEO satellites causes such debilitating latency while using the internet and performing other mission-critical communications, aren’t there other options? There sure are and there is a lot of work being done right now to utilize both Medium Earth Orbit (MEO) and Low Earth Orbit (LEO) satellites. Actually, the correct term to use is “satellite constellations” since these solutions rely on many satellites working together and sharing information in a more networked/mesh type of environment, rather than a single GEO satellite illuminating half of CONUS.

LEO satellites orbit at a distance of 500-1000 miles and MEO satellites orbit at a distance of ~8000 miles. So for LEO constellations, there is promise for latency to be greatly reduced to values approaching current, wired-internet norms. But there are still major technological challenges to fielding interconnected systems (constellations) of LEO/MEO satellites:

• Need to hand off coverage between satellites as one satellite leaves an area and another replaces it;
• Need for beam-forming and adaptive steering to maximize SNR
• Need for motorized antenna mounts in cases where one needs to stay locked onto a specific satellite

Many of these challenges are already being addressed with the 1-2 thousand satellites currently in MEO and LEO orbit. Several companies are launching more satellites this year and according to Northern Sky Research, “over 4,000 Non-GEO HTS satellites are forecasted to launch by 2028, from OneWeb, SpaceX, Telesat, LeoSat, Amazon, and SES.”

Final Thoughts

Currently, satellite internet is a great option to have in rural areas or other locations where wired internet is not available. While performance right now is not very good, over the next few years performance, pricing, and availability are all moving in the right direction for consumers.

For mission-critical SATCOM use cases, performance enhancing proxies and SD-WAN bonding of the satellite links can significantly improve end-to-end performance.

Rob Stone, Mushroom Networks, Inc. 

Mushroom Networks is the provider of Broadband Bonding appliances that put your networks on auto-pilot. Application flows are intelligently routed around network problems such as latency, jitter and packet loss. Network problems are solved even before you can notice.

https://www.mushroomnetworks.com