telecommunication networks: Satellite Internet Access - 1.Introduce satellite In
ID: 3738375 • Letter: T
Question
telecommunication networks:
Satellite Internet Access -
1.Introduce satellite Internet access by explaining where it is best utilized.
2.Define and describe geosynchronous orbit.
3.Define and describe LEO (low Earth orbiting) satellites.
4.Define and describe MEO (medium Earth orbiting) satellites.
802.16 (WiMAX) -
1.Define and describe WiMAX.
2.Describe the two distinct advantages WiMAX has over Wi-Fi.
3.Discuss possible best uses for WiMAX.
4.Describe WiMAX MAN service.
5.Note the one big disadvantage of WiMAX at this time.
Cellular -
1.Define and describe cellular networks.
2.Explain the architecture of cellular networks.
3.Describe the performance characteristics of the digital cellular networks.
Wireless WANs -
1.Introduce and describe wireless broadband.
2.Review how access points figure into home networks and enterprise wide LANs. (e.g. which standards?)
3.Define and describe a hotspot.
Explanation / Answer
1.Introduce satellite Internet access by explaining where it is best utilized.
Answer:
Satellite Internet access refers to Internet access provided through satellites. In other words, it is a telecommunications network provided by orbital communication stations. Signals from these satellites allow a user with a dish to have a high speed internet connection.
Satellite Internet access is useful in remote regions and newly developed areas. It can provide high speed Internet service where conventional cable or DSL is either not available or not functioning well. However, it is complex to install and expensive compared to a DSL or cable connection. The satellite Internet speed is similar to DSL and cable services. However, the service differs in that it is an always-on connection.
2.Define and describe geosynchronous orbit.
Answer:
Geostationary orbit is a type of geosynchronous orbit of a satellite whereby it moves with the same speed as the rotation of the Earth. Because it orbits at the same speed as Earth revolves, a geostationary satellite seems to be stationary if seen from the surface of the Earth.
Geostationary orbit is also known as geostationary Earth orbit and geosynchronous equatorial orbit.
A satellite in geostationary orbit remains exactly above the equator, so it does not change its position with respect to a location on Earth. A geostationary orbit is a path given to high Earth orbiting satellites to monitor weather and for observational and telecommunication purposes. High Earth orbits are orbits that are around 22,236 miles (35,786 kilometers) directly above Earth's equator. This position is ideal since Earth’s gravitational pull is exactly such that the speed of the satellite is kept equal to the orbit velocity of the Earth.
3.Define and describe LEO (low Earth orbiting) satellites.
Answer:
Low earth orbits (LEO) are satellite systems used in telecommunication, which orbit between 400 and 1,000 miles above the earth's surface. They are used mainly for data communication such as email, video conferencing and paging. They move at extremely high speeds and are not fixed in space in relation to the earth.
LEO-based telecommunication systems provide underdeveloped countries and territories with the ability to acquire satellite telephone service in areas where it otherwise would be too costly or even impossible to lay land lines
Low earth orbit is defined as an orbit within a locus extending from the earth’s surface up to an altitude of 1,200 miles. Attributing to their high speeds, data transmitted through LEO is handed off from one satellite to another as satellites generally move in and out of the range of earth-bound transmitting stations. Due to low orbits, transmitting stations are not as powerful as those that transmit to satellites orbiting at greater distances from earth’s surface.
Most communication applications use LEO satellites because it takes less less energy to place the satellites into LEO. Moreover, they need less powerful amplifiers for successful transmission. As LEO orbits are not geostationary, a network of satellites are required to provide continuous coverage. However, as a result of the popularity of this type of satellite, studies reveal that the LEO environment is getting congested with space debris. NASA keeps track of the number of satellites in the orbit, and estimates that there are more than 8,000 objects larger than a softball circling the globe. Not all of these objects are not satellites, but rather pieces of metal from old rockets, frozen sewage and broken satellites.
4.Define and describe MEO (medium Earth orbiting) satellites.
Answer:
A medium earth orbit (MEO) satellite is one with an orbit within the range from a few hundred miles to a few thousand miles above the earth's surface. Satellites of this type orbit higher than low earth orbit (LEO) satellites, but lower than geostationary satellites.
The orbital periods of MEO satellites range from about two to 12 hours. Some MEO satellites orbit in near perfect circles, and therefore have constant altitude and travel at a constant speed. Other MEO satellites revolve in elongated orbits. The perigee (lowest altitude) of an elliptical-orbit satellite is much less than its apogee (greatest altitude). The orbital speed is much greater near perigee than near apogee. As seen from a point on the surface, a satellite in an elongated orbit crosses the sky in just a few minutes when it is near perigee, as compared to several hours when it is near apogee. Elliptical-orbit satellites are easiest to access near apogee, because the earth-based antenna orientation does not have to be changed often, and the satellite is above the horizon for a fairly long time.
A fleet of several MEO satellites, with orbits properly coordinated, can provide global wireless communication coverage. Because MEO satellites are closer to the earth than geostationary satellites, earth-based transmitters with relatively low power and modest-sized antennas can access the system. Because MEO satellites orbit at higher altitudes than LEO satellites, the useful footprint (coverage area on the earth's surface) is greater for each satellite. Thus a global-coverage fleet of MEO satellites can have fewer members than a global-coverage fleet of LEO satellites.
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