Features of Satellite Broadband
Bandwidth pertains to the amount of data that is sent and received by ISPSs and satellite broadband companies. This amount is measured in terms of megabits per second, or roughly one million bits per second.
There are approximately 300 satellites located on a fixed geostationary orbit, just above Earth’s equator, with 2-3 degrees distance in between. These satellites move withthe world at the same speed. Ground stations can locate geostationary satellites at a fixed location relative to the globe’s equator.
Three things should be carefully considered when evaluating the capacity of satellite carriers: downlink EIRP power (dBW), transponder bandwidth (MHz), uplink G/T (dBK) and sensitivity (dBW/^m2), which is bought by ISPs and satellite operators.
In determining the equivalent data rate for bandwidth (MHz), the following variables are taken into account: modulation method (e.g 8-QAM , 16-QAM, BPSK, QPSK) the type of FEC (e.g. Turbo Code, Reed Soloman, Low Density Parity Check, Viterbi or combinations of these), and the forward error correction code. The overall capacity can also be affected by dish size.
The maximum size of satellite coverage can be as much as 33% of Earth’s surface, so a satellite located atop India can send and receive signals to and from Europe, South Africa, Australia and Japan. Spot beams are directed toward certain areas equipped with small satellite dishes.
Satellite signals are sent by a small dish (60cm to 3.7m diameter) with a receiver and transmitter module. There is an indoor device that can process the signals and send them in brief TDMA bursts when users send a command to the server.
It is common for satellite broadband providers to charge users based on a bit rate per second. Assuming that a certain Internet plan has 512k download /64k upload speed and user:host ratio of 20:1, monthly fee can reach $202 per computer terminal. This package is good for two computers per site.
Like mobile broadband carriers, VSAT operators have a so-called fair usage policy. Subscribers who fail to keep their bandwidth usage within the maximum limit can be penalized through sluggish Internet connection or lower bandwidth limit.
Satellite broadband is a great help to mobile business travellers and companies operating in very remote locations. Many industries like airlines, broadcasting firms, banks and shipping lines manage to access the Internet and GSM services through VSATs. Furthermore, satellite connection is a good data recovery and back-up connectivity solution for Internet-reliant enterprises and government agencies.