How Satellite Internet Services Work

Satellite Internet access is the system that lets you get Internet connection through communication satellites. Internet access services are typically brought to users by means of geostationary satellites, capable of providing high data speeds.
The whole system relies on the following primary components:

• A satellite in a geosynchronous Earth orbit (GEO);
• Several gateways (ground stations) that relay Internet information via radio waves;
• A very-small-aperture terminal (VSAT) dish antenna located at the premises of the subscriber.

Other components of satellite Internet systems include a modem that links the network of the user with the VSAT antenna, and a NOC (network operations center) that monitors the entire system. The satellite works with a Star network topology that allows a practically limitless number of VSATs to be connected to the network.

The Satellite as the Central Piece of the Satellite Internet Puzzle

The broadband satellite networks have GEO satellites of the latest generation at their center. These satellites are positioned 35,786 km above the equator and operate in Ka-band mode (18.3-30GHz). They are designed for broadband applications and use narrow spot beams meant to target a smaller area compared to the earlier communication satellites that used broad beams. This technology allows the assigned bandwidth to be used multiple times, and the capacity is higher than what conventional satellites could offer.
The satellite works as a bridge, allowing the connection between points situated on the ground. It is the middle of the so called bent-pipe architecture. This term describes the shape that the data path takes between antennas, with a satellite placed at the bend point.
There is also a set of antennas at the satellite, receiving communication signals from the Earth and transmitting signals to target locations.

Gateways to the Sky

Following the important changes in satellite technology that took place over the recent years, ground equipment has also evolved, as a consequence of higher integration and increased processing power.
The Gateway Earth Station, or simply Gateway, is also known as a teleport, ground station, or hub. Sometimes, the term is used to describe just the portion including the antenna dish, or it can describe the entire system, with all the associated components.
The gateway receives the radio wave signals emitted by the satellite. A modem situated at the gateway location performs a demodulation of the incoming signal into IP packets that are then sent to the local network.
The gateways manage traffic to or from the Internet. The system of gateways provides all the services necessary for satellite and terrestrial connectivity. In the continental part of the United States, the gateways must have a direct unobstructed view to the southern sky. Since the satellite’s orbit is geostationary, the antenna can point at a fixed position.

What Are the Dishes Good for?

In order to get satellite Internet access, a user must have some additional components installed, besides a PC and a router.
The outdoor unit is a reflective radio antenna having the form of a dish, constructed from a variety of materials. It must have a direct view to the sky, in order to allow adequate line-of-sight to the satellite. The antenna must be positioned correctly and, therefore, a set of four parameters is necessary: azimuth, elevation, polarization and skew.
The indoor unit necessary to get satellite Internet connectivity is a modem that acts as an interface between the outdoor unit and the customer’s equipment. It controls satellite reception and transmission.
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Written by Robert Kleymore
Internet technology expert, MIT graduate and a passionate blogger.