Satellite Communication & Internet Access

In the past decade, communications networks have experienced a huge amount of growth. This is especially true when it comes to broadband Internet access. Connectivity has become more and more extensive as both the public and private sectors invest in infrastructure, giving more and more individuals and businesses access to increasing bandwidth. Many rural and far outlying areas all over the globe that were limited to slow dial up or unreliable broadband connections in the past are now enjoying DSL, cable, and even fiber optic connections. High-bandwidth networks are also utilized by the media to stream live video and audio to televisions and computer screens across the world.

Despite Growth in Network Infrastructure, Some Areas without Wired Internet Access
However, despite this growth in access to the internet, many areas are under served and some are completely without any access. This is where satellite internet access is frequently an effective solution because it allows access virtually anywhere on the planet, provided you have the appropriate equipment, software, and configuration along with an account with the satellite ISP. Although accessing the internet over satellite is among the most expensive methods around, it is often the only way in many areas across the globe.

Satellite Communications Might Be the Solution
In some cases, the connection is setup to function from a fixed location, such as an isolated factory, mining operation, a weather station, a government consulate, etc. In this case, the satellite antenna or dish is installed as a permanent setup and calibrated to achieve the best possible connection. Another possibility is a temporary setup, which is more appropriate with temporary or mobile applications such as a news van. Another example is when a business user travels to a remote area and needs internet access onsite. Many broadband satellite systems are highly mobile and can be operational within minutes of setup.

Cost of service can vary a large degree, but usually depends on a number of factors such as bandwidth, the satellite/network being utilized, volume of data, and other factors. As a point of comparison, residential service in the United States starts at around $50 per month for a relatively slow connection of around 512 kbps downlink speed and 128 kbps uplink speed. Commercial-grade worldwide service can cost well over $5,000 per month for slightly faster speeds and a data allowance of a few gigabytes. The reason for the large difference in price has to do with the cost of providing access to far outlying areas.

There are Some Potential Problems with Satellite Communication and Internet Access
Satellites in a geostationary orbit, which can be achieved at about 35,000 miles above Earth, orbit the planet at the same rate it rotates on its axis. This means that the satellite will always be above the same areas of the planet. The second category of satellites are those that orbit at a different altitude than those in Geostationary orbit and, as a result, pass over different areas of the earth as it orbits. These satellites are either in a Low Earth Orbit (LEO) or a Medium Earth Orbit (MEO).

No matter the distance from the ground, the signal has a long way to travel between the orbiting satellite and the ground station. As a result, a phenomenon known as signal latency makes many applications such as VoIP more difficult if not impossible to use over a satellite connection. The reason is that with these applications, constant interaction between two or more parties is taking place and, unlike email or web browsing, the lag will be noticeable. For this reason, users of satellite data transmission typically use it for applications that do not require real time lag-free connections.

Although it is not possible to reduce latency with satellites in a geostationary orbit, there is less of a lag with Low Earth Orbit (LEO) and Medium Earth Orbit (MEO) satellites. The remarkable thing about these satellites is how much closer they are to the surface of the earth than those that are in a geostationary orbit (GEO). Whereas a GEO satellite is 35,786 km above the earth, a MEO satellite orbits at an altitude between 20,000 km and 8,000 km and a LEO satellite is in an orbit as low as 500 kilometers above the earth! Although these are all quite a distance away from the surface of the planet, sub-geostationary orbiting satellites are comparatively much closer; at least enough so to significantly reduce connection lag.

Geostationary vs. Low Earth Orbit vs. Medium Earth Orbit Satellites
Perhaps the best aspect of having a satellite in geostationary orbit is that it can cover almost a third of the earth''s surface. The "stationary" in geostationary might sound misleading, but it refers to the fact that, although it is moving at a very fast speed, the satellite remains over the same area of the earth. This is because it takes exactly 24 hours to complete an orbit around the planet, the planet rotates on its axis at the exact same rate, and the satellite is positioned above the equator. This can also be a beneficial aspect of a satellite in geostationary orbit because, if a satellite is always positioned over the same area, antennas on the ground can be fixed in one static position.

Although MEO and LEO satellites do not cover as great a range as GEO satellites at any given moment, they are quite useful for certain applications. For example, these satellites can orbit the earth in well under a couple hours and are frequently used for covering the North and South Pole areas not served by GEO satellites at all. Although one specific area only has a window of time to utilize one particular satellite in this kind of orbit, coverage can be maintained by utilizing multiple satellites in the same orbit, but at a distance from one another. These satellite constellations are used for a variety of purposes, notably by companies such as Iridium and Globalstar to provide satellite telephone service.

Some Uses of Satellites for Communications and their Methods
Beyond commercial and household Internet access, satellites are used for a wide range of applications and the way in which they transmit and receive data can vary. For example, a television network might broadcast a transmission to their affiliates across the country or the world by using what is known as a Simplex Transmission. This is where a station at a fixed location beams a transmission up to a satellite, which them beams it back down to other stations in various fixed locations on the ground. This sort of connection is one-way in that the receiving stations cannot transmit data back to the transmitting station, at least not through the same route.

For two-way communication, a Point-to-Point Duplex Transmission may be used. This allows data to be sent and received by the same equipment over the same connection, making it a great option for transporting data. This option is also used for private corporate networks, telephone service, content distribution and many other applications. Point-to-Multipoint Transmission is a similar topology and is used by consumers for Internet access in their homes. It is also used by companies for their corporate television networks, giving them the ability to deliver content to their many locations scattered across the country. Mobile Antenna Service is used by television stations to beam live video and audio back to the station using a one-way transmission from a mobile satellite truck up to the orbiting satellite and back down to the fixed base station.