There has been a lot of discussion regarding broadband internet to rural areas in the last couple of years. Rural areas are expensive to connect for fiber to the home (FTTH), and most CATV systems do not reach rural users for the same reason. Many rural areas also do not have good cellular coverage, especially with enough bandwidth to deliver internet data.

Methods for delivering internet to rural areas

The least costly methods to deliver internet to rural areas are line-of-sight wireless and satellite. Line-of-sight wireless requires a fiber connection within sight of the user, while satellites can provide coverage anywhere you can see the sky and have a satellite overhead.

Satellite networks are complicated, especially for the internet. You need to launch satellites to cover the area, and you need an extensive ground network of stations to connect by fiber optics to the internet and satellites. And, of course, like anything based on launching stuff into space, satellites are expensive.

Types of satellites

There are two types of satellites: geostationary satellites and low Earth orbit (LEO) satellites. They are very different in operation.

Geostationary satellites

Geostationary, or geosynchronous satellites, are very large and placed in orbit at about 36,000 km (22,000 miles) above the equator. At this altitude, they maintain position above a single point on the Earth because their orbital period is the same as the Earth’s rotation. They can communicate continuously with devices within the coverage of the satellite’s antennas. Because these satellites are large, they can support many users at reasonable internet connection speeds.

The first geostationary satellites like the Telstar shown above were used for telephone conversations between continents instead of using undersea cables, which had proven problematic for wired communications because of limited bandwidth and reliability. Later satellites were adapted to service the internet.

Geostationary satellites can cover large areas of the Earth with many users, so they are big—the size of a bus or truck—with many antennas. They have a network of Earth stations connected to the internet or private networks on fiber optics that provide uplinks and downlinks to the internet for the devices connected to the satellite. Users must have their own antenna and electronics for their uplink/downlink to the satellite. 

Users of geostationary satellites must have an antenna pointed directly at the satellite, similar to those used in satellite TV. However, these antennas must be bidirectional, capable of sending signals up to the satellite and receiving signals from it.

All satellites suffer from limited bandwidth. Bandwidth requires radio frequency spectrum and power at the satellite, both of which are limited. The other downside of geosynchronous satellites is latency. It takes about 240 milliseconds for the signal to get from Earth to the satellite and return, which made voice conversations with the delay annoying. Latency is also a problem for internet users because a click on a link on a browser means it takes about a second for a response. As the signal goes to the satellite, the satellite processes the request and sends it down to a data center on the ground, uploads the requested data and then downloads it to the user. In internet time, that is a long time.

Low Earth orbit satellites

LEO satellites are small and orbit at around 550 km (340 miles) above the earth and zoom over an Earth station at high speeds. These small satellites have limited bandwidth and orbit at a low altitude, their antennas cover a limited area with fewer users. That also means that a large number of LEO satellites are required to provide wide coverage. Most current and proposed systems involve thousands of small satellites to provide adequate coverage.

LEO satellites move at a very high speed. Because the satellites pass overhead quickly, the earth stations must track them continuously. The user must be passed off from satellite to satellite continuously to provide constant internet service.

Since it is difficult to have sufficient numbers of ground stations for wide coverage, especially coverage in rural areas, LEO satellite networks may use inter-satellite connections (even using lasers for higher bandwidth than radio) to relay signals between satellites to reach end-users who are remote from ground stations, essentially creating a matrix network among the satellites.

These satellites require a complicated Earth-based communications network involving many ground stations (connected on fiber, of course) to connect to the satellites. They even use satellite-to-satellite links (using lasers in space in one instance) to connect to the internet. The complication of the LEO network means multiple links add latency, but since the uplink to the satellite is only about 4 milliseconds, the total latency is much less that geostationary satellites, and perhaps even comparable to the ground-based internet with its multiple switching options connecting users to data centers.

Users must have their own antenna and electronics for their uplink/downlink to the satellite, but it is much more complicated than with geostationary satellites because it must track fast-moving satellites and jump from satellite to satellite as they pass overhead. The antenna is an electronic phased-array antenna that tracks the satellite electronically instead of mechanically and can switch from satellite to satellite instantaneously.

Advantages and disadvantages of using satellites

Satellites are an excellent option for internet access in remote or rural areas. It is even possible to use some of these services on boats or vehicles as well as buildings or homes. The disadvantages, compared to FTTH or HFC DOCIS cable systems, are cost and bandwidth. Both these offer services up to gigabit speeds, generally without usage limits. Satellites are much slower, similar to those of DSL, and generally will have usage limits that can affect video streaming and gaming. The advantages for remote communications also make satellites popular for government and military use.

Image credits: Bell Labs / Jim Hayes