DSL

DSL (Digital Subscriber Line) is a technology for bringing high-bandwidth information to homes and small businesses over ordinary copper telephone lines. xDSL refers to different variations of DSL. DSL is a broadband technology that allows for high-speed Internet connectivity over traditional twisted-pair copper telephone lines, thus eliminating the need for costly infrastructure upgrades common with other technologies. The ability to implement DSL service within the confines of existing telephone lines makes it both affordable and practical for small businesses and residential homes, allowing for high-speed connectivity for interactive gaming, on-demand streaming audio and video entertainment, and for downloading huge files in seconds instead of minutes.

How does DSL work?

DSL allows for greater bandwidth by utilizing more of the bandwidth available on a common analog line and connecting digitally on both the uplink and downlink connection. DSL modems can provide downlink connection speeds greater than 6 Mbps and uplink speeds of 640 Kbps. With DSL, bandwidth rates available are more consistent to the end user. There is a geographic requirement that the end user must be within 18,000 feet of the central office or signal degradation will become too great and DSL unfeasible.

Family of DSL technology includes

ADSL Line

HDSL Line

IDSL Line

SDSL Line

VDSL Line

Why so many types?

People have different needs.Most xDSL technologies are used to provide internet access of some sort, but what is needed from that service varies greatly from case to case. The needs of a home user with only one or two computers on a line are quite different from the needs of a business network running collaboration software or web server/file server.

ADSL

ADSL is the acronym for Asymmetric Digital Subscriber Line. ADSL derives its name from the fact that the data transfer rates downstream are much faster than the upstream data rates. more>

ADSL2+

ADSL2+ is the next generation of ADSL broadband with lightning-fast download speeds and super-fast upload speeds, many times faster than regular ADSL broadband. more>

SDSL

SDSL (Symmetric DSL) is similar to HDSL with a single twisted-pair line, carrying 1.544 Mbps or 2.048 Mbps each direction on a duplex line. It's symmetric because the data rate is the same in both directions. SDSL is an cost effective alternative to traditional leased lines.SDSL products are aimed at businesses and come with an increased up channel speed to match the downstream. SDSL is ideal for those customers who exchange large files or host services at their premises. They also make ideal services for those customers who want larger bandwidth but do not need an uncontended service.

HDSL/VDSL

HDSL (High bit-rate Digital Subscriber Line), one of the earliest forms of DSL, is used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that it is symmetrical: an equal amount of bandwidth is available in both directions. HDSL can carry as much on a single wire of twisted-pair cable as can be carried on a T1 line (up to 1.544 Mbps) in North America or an E1 line (up to 2.048 Mbps) in Europe over a somewhat longer range and is considered an alternative to a T1 or E1 connection.

VDSL (Very high bit-rate Digital Line Subscriber) is next generation DSL at super-speed rates of 13-52 Mbps downstream and 1.5-2.3 Mbps upstream. VDSL is the highest-rate DSL technology available, is the next generation of DSL, with higher throughput and simpler implementation requirements than ADSL. VDSL is both symmetric and asymmetric.VDSL is nearly ten times faster than ADSL and is over thirty times faster than HDSL. Providing high-speed Internet access is an essential value for home users, small business, hotels, institutions and other multidwelling buildings.

SHDSL

(Symmetric High-speed Digital Subscriber Line) was based on HDSL and is specified in the International Telecommunications Union (ITU) recommendation number G.991.2 titled Single-Pair High-Speed Digital Subscriber Line Transceivers. Today SHDSL can operate at data rates from 192 kbps to 2.312 Mbps (in a 2-wire mode) and 384 Kbps to 4.624 Mbps (in a 4-wire mode) with higher rates under development, and is spectrally compatible to all other DSL technologies with the use of TC-PAM line coding. SHDSL combines the best of the legacy services into a single, robust technology that can be used for both full and fractional E1/T1 lines, Digital Added Main Lines (multiple voice channels), and video conferencing applications using a single twisted pair of wires.

G.SHDSL ( Symmetric High bit rate Digital Subscriber Line)

G.SHDSL is a standards-based, multirate version of HDSL-2 and offers symmetrical service. The advantage of HDSL-2, which was developed to serve as a standard by which different vendors' equipment could interoperate, is that it is designed not to interfere with other services. However, the HDSL-2 standard addresses only services at 1.5 Mbps. Multirate HDSL-2 is part of Issue 2 of the standard known as G.SHDSL, and is ratified by the ITU. G.SHDSL builds upon the benefits of HDSL-2 by offering symmetrical rates of 2.3 Mbps.