Broadband Guide, Meaning , Facts, Information and Description
| Table of contents |
|
2 Modem 3 Broadband Internet 4 Multiplexing 5 See also 6 External links |
Hardware
Broadband is a type of transmission method where two or more signals to share a medium. This is in contrast to a baseband transmission where one type of signal uses a medium's full bandwidth such as 100BaseT Ethernet. While people profess that narrowband is a description of the amount of bandwidth a medium has, it is still debatable whether the term exists in network engineering circles. The obvious example of a broadband type transmission is ADSL where voice and data share two different parts of the spectrum of a copper wire (voice operates below 3,300 Hz and ADSL starts at 138 kHz in the case of G.dmt).
A channel may be broadband because even though the signal is modulated on a carrier, it is done in a way to maximise the bandwidth over the channel - examples of this include ADSL (which splits up the signal into parts and sends each part over a separate carrier in order to maximise the usage of the frequency spectrum that the wire can carry).
It's ALWAYS ON. No waiting to dial in.
Recently, the term Broadband has been hijacked by Internet Service Providers (ISPs) to refer to a particular style of Internet access, called Broadband Internet access, where the connection used for access is greater than a telephone modem (56 kbit/s). It is generally accepted that the term is used to mean a connection of 512 kbit/s (0.5 Mb) or above for the final user, utilizing a broadband modem and the FCC definition of broadband is 200 kbit/s (0.2Mb) in one direction, and advanced broadband is at least 200 kbit/s (0.2 Mb) in both directions, though some Internet Service Providers have marketed services with a shorter bandwidth because there is no specific bitrate defined by the industry. On August 13, 2004 the ISP Wanadoo were told by the Advertising Standards Authority to change the way that they advertised their 512 kbit/s broadband service in Britain, removing the words "full speed" which rival companies claimed was misleading people into thinking it was the fastest available service. In a similar way, on April 9, 2003 the Advertising Standards Authority ruled against ISP NTL, saying that NTL's 128 kbit/s cable modem service must not be marketted as "broadband".
By the above definition, a telephone modem is a broadband connection (because it uses clever tricks to carry 56 kbit/s over a link that has an ultimate bandwidth of 64 kbit/s), and a cable modem is a narrowband connection (because the data is modulated over a carrier signal somewhere between 20 MHz and 500 MHz - the ultimate bandwidth of the coaxial cable is huge), even though the cablemodem connection can be forty times faster (or more) than the POTS modem.
Communications may utilise a number of distinct physical channels simultaneously; this is multiplexing for multiple access. Such channels may be distinguished by being separated from each other in time (time division multiplexing or TDMA), in carrier frequency (frequency division multiplexing (FDMA) or wavelength division multiplexing (WDM)), or in access method (code division multiplexing or CDMA). Each channel that takes part in such a multiplexing exercise is by definition narrowband (because it is not utilising the whole bandwidth of the medium), whereas the whole set of channels taken together and utilised for the same communication could be described as broadband.
This is an Article on Broadband. Page Contains Information, Facts Details or Explanation Guide About Broadband Modem
Broadband Internet
Multiplexing
See also
External links