Digital Subscriber Line (DSL) Internet Access
Digital Subscriber Line (DSL) is a broadband technology that leverages the existing telephone system to provide high bandwidth data transfers. At first glance, DSL modems look like regular analog modems. They interface your computer to an external network managed by the service provider and communicate with a compatible modem on the other end by converting digital data into modulated radio frequency (RF) signals. What makes these broadband DSL services so much faster is that a much wider range of spectral bandwidth is being used. DSL technology uses line coding algorithms to effectively divide the sprectrum on copper phone wires between voice and data allowing for the simultaneous use of both applications. After the higher speed, the ability to talk on the phone while transferring data is the key highlight of this technology.
DSL replaces the local loop to a home or business. In the carrier's central office, the DSL line first passes through splitters to split off the telephone voice channel that is routed into the phone network equipment. The data channel is terminated on a DSL multi-plexer (DSLAM) which links the DSL access line to other data networks. And so we get simultaneous voice and data communications.
People who work at home need to be directly connected to the corporate networks at high speeds. Unlike Internet users, telecommutes use high bandwidth in both directions, whether working in collaborative activities using groupware applications or sharing large files. They ideally require two way burst bandwidth capacity in the megabit range. Most service providers offer tiered services that allow one to match the bandwidth performance with price of the service.
DSL connections can be easily shared amongst multiple users on a LAN (wireline or wireless) with the addition of a cheap broadband router.
DSL comes in many different flavours; some of them being:
Asymmetric Digital Subscriber Line (ADSL):
ADSL delivers transfer rates between 32Kbps to 8.2Mbps downstream
and 32Kbps to 1.1Mbps upstream. This technology is well suited for
Internet Access where a higher downstream capacity is needed.
Rate Adaptive Asymmetric Digital Subscriber line (RADSL):
RADSL is the most flexibe DSL solution, allowing sevice providers
to adjust bandwidth to fit the need of the application and depending
on the line conditions. It also lets them charge different amounts
for these different services.
High-bit-rate Digital Subscriber Line (HDSL):
HDSL can provide full duplex T1 (1.544 Mbps) or E1 (2.048 Mbps)
across traditional copper lines and is an attractive alternative
to fiber for business applcations.
Very High-bit-rate Digital Subscriber Line (VDSL):
VDSL boosts the data rates to T3 levels. The close a customer is
located to the central office, the faster the transfer rates which
range between 51 Mbps (1000 feet away) to 13 Mbps (5000 feet away).