| KWIUG OCTOBER
28/97: Future Trends In Bandwidth Bandwidth bandwidth is a measure of the carrying capacity of a communications link. It determines the maximum amount of information that can be transmitted over that communications link.
In a general sense, this term describes information-carrying capacity. It can apply to telephone or network wiring as well as system buses, radio frequency signals, and monitors. On a more human level, the term can describe a person's capacity for dealing with multiple projects ("I'd like to update this database, but I don't have the bandwidth."). Bandwidth is most accurately measured in cycles per second, or hertz (Hz), which is the difference between the lowest and highest frequencies transmitted. But it's also common to use bits or bytes per second instead. Glossary:
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| GEO: geosynchronous earth orbit, orbit at 22,238
miles above the earth's equator. The period of rotation
of the satellite around the earth is exactly 24 hours.
Also know s the Clarke orbit for Arthur C. Clarke that
posited in 1945 that it would be possible. Most of
today's satellites are GEOs. MEO: medium earth orbit satellites orbit at altitudes between 6250 and 12,500 miles. Unlike GEOs, their position changes relative to the earth's surface. At their lower altitudes, you need more to them to achieve complete coverage of the earth's surface, but the latency reduces substantially. Right now there are not many MEOs, and the ones in orbit are used for positioning. LEO: Low earth orbits promise extremely high bandwidth and low latency. Plans exist of hug constellations of hundreds of satellites that will cover the entire globe. LEOs generally orbit below 3125 miles. Most of them are much lower: only 400-1000 miles. At these altitudes latency reduces to nearly negligible times - hundredths of a second. There are 3 kinds of LEOs: little LEOS that handle low-bandwidth applications (tens to hundreds of Kbps) such as paging . Big LEOs can handle paging, cellular services and some data transmissions.(hundreds to thousands of Kbps). Broadband LEOs or mega-LEOs operate in the Mbps range. HALE: High-altitude, long-endurance platforms are basically solar-powered, lightweight airplane or lighter-than-air craft that hover over an unmoving spot some 70,000 feet above the earth's surface. Primarily a research venture. |
Bandw